This authors testing setup evaluation motors props results shown tables discussed text power supply fully adjustable zero 30 volts up 20 amperes two digital readouts motor voltage current analog meter tachometer optical pickup remotely located under motor mount Light source also remotely located Photos author THE FIRST INSTALLMENT series September issue described some pros cons electric-powered models last month covered motors use Some basic aspects motors de scribed practical considerations covered Earlier asked have faith read daringly onward remind because realize subject part may appear both simple some strange others However think some up coming information will surprising interesting manyand perhaps little confusing ditficult others first reading still others some what fol lows may downright boring seem totally irrelevant taken alone section however combined ether parts series will provide very intimate overall feel exactly what \Ki O iOE ra popellor rave electricpowered models yoi re new Electrics authors test results may astound second reading may required fully grasp some points thai made that1s what takes suggest Part 3 November 1983 93 goes motor battery pro peller given planeand affect flight results get other words series continues will come together' encourage un daunted continuance series Im sure will find worthwhile presentation seems too slow 80 70 60 -50 40 -8 tedious remern ber introduction Electricson installment plan Its necessarily easy installment plan either read write Hox ever maintain subject can generally simple oc t V 0 0 0 ----V e Lu 0 0 0 0 0 -I C V e 0 V C 0 0 RPM X 1000 91011 SC V0 certainly successful though neces sadly short Perhaps some readers have disap pointments Electrics just because some details made light glossed over elsewhere Thats Model Avi ation has planned seriesto make sure adequate introductory treatment such anyone wants can very successful Electric flier theres some useful stuff Gas guys honest well-intended series cannot complete detail-perfect several reasons dont know everything Another Im trying se lect meaningful useful offer ings consistent limitations pub lication space presentation time can fact best can can criticautomaticallyby asking questions 1 Propellers power Now Chave seen some Electric models Part have some introductory insight motors Part 2 could wondering what business concerning power heating performance about Lets look what happens motor required its thingturn prop power plane leading suppliers Electric flight systems provide instructions regarding choice model size weight suit able propellers things will also addressed another part series meantime get good feel motor operation propellers power lets look things static environment ie bench rather flight experience excellent correlation tween what observe bench what experience air A Power inputno prop Electrical power product electric potential volts electric current amps case motor input power motor terminal voltage times motor terminal input current amperage product V x power watts power comes frm energy 12131415 tank battery tank specific size can deliver its fill Part 4 will cover batteries detail discuss much tanks' can deliver Now however going get feel just Shown motor input power various motor speeds rpm 11 samples nine different motor types swinging Cox 6-4 gray prop Note different symbol 11 motors Connect like symbols form smooth performance curves through various speeds Note generally tight clusters data points throughout range test 94 Model Aviation Table 1 Typical Motor Power InputNo Prop MotorVoltsAmpsWatts Astro 0560075450 p/n 210770078546 80081648 90084756 Leisure LT-5050119595 Pattern Wind60124744 7013091 Mabuchi5011859 RS540S65276013078 70146102 80153122 Table 2 Performance Variation Various Same Size Props Propeller 64AmpsWatts Top Flite Nylon1168113300 Top Flite Wood13393112700 Cox Gray155*10912200 Table 3 Typical Motor/Propeller Performance Voltage Variation VoltsAmpsWattsRPM 60795488000 65905598550 70100709050 75110839600 801219710000 8513011110500 133 120 110 100 90 much fuel used motors next month youll have appreciation Part 4 As mentioned earlier motor running no prop draws small amount current sufficient overcome losses due friction other things illustrate sev eral examples shown Table measurements made using test setup pictured Notice something particular about data Table example motor current increase large crease voltage caused will case prop measurements tests made using convenient adjustable power supply exactly same re sults would occur motor bat tery interested power supply pictured capable up 30 volts 20 amps has remote voltage sense assure correct voltage motor terminals Also has adjustable current limit dont have accident during some zealous data run power capa bility may sound impressive believe expect need capability near future point want make special note has experience Ive told same Electric flight system suppliers performance production flight motors varies about plus-or-minus 10% As youll also see props also vary greatly load present motor battery course measurement motor performance has instrumentation accuracy associated Thus rea sons apparent differences Electric flight experience can occur Em noting now just case anyone reading has has read about different results B Power inputwith props ifl tables various motor performance mea surements different props ahown Whats mportant absoLve ac curacy relative performances -i particuiar notice bow rapidly input power changes tbattery voltage dra matic eFfect piop size can hae youll see important use right prop temptation just stick bigger prop add another cell may have carefully con sidered What seems like small change may fact either present unbearable load motor lest cause decline power system efficiency Remember static demonstrations motor/prop moving forward actual flying condi tions aircraft speed etc can have signifi cant influence data 1 All propellers same size necessarily created equal demonstrate ran Leisure LT-50 Pattern Wind very nicely-made motor three different 6 X 4 props applied voltage held constant 70 volts much like battery would hold nearly-constant voltage Table 2 lists resulting current drain input power rpm Notice wide variation power input roughly translates about same variation power output flight per formance might inclined say prop better prop remember dont get something nothing output performance input power means faster battery dis charge shorter flight timealthough increased flight performance may very well worth depending plane want fly some simi larity running engine full bore vs half throttle latter goes longer tank fuel Does Cox 6 x 4 gray fly aerobatic Jack Rabbit hotter Top Flight 6 x 4 nylon betcha buddy gives shorter flight too 2 A small change voltage makes big change performance demon strate propped Mabuchi Continued page 170 November 1983 95 Table 4 Effect Propeller Pitch Motor Input Power PropAmpsWattsRPM 8-468487950 8-580567550 8-696677000 8-8117826200 Table 5 Effect Prop Diameter Motor Input Power PropAmpsWattsRPM 6-437269000 7-450358400 8-469487900 Table 7 Some Larger Motor/Prop/Power Demonstrations MotorPropRPMPower Astro 259-6 wood700086 watts Astro 109-6 wood700090 watts Astro 075* *9-6 wood700080 watts Astro 259-6 wood8000126 watts Astro 075* *9-6 wood8000115 watts Astro 2512-6 wood5100115 watts Astrol5**12-6wood510096watts Now 1 ** means motors used matching speed reducers 2 In cases motor clearly over-propped operating conditions carefully controlled no risk motor involved 3 No voltages currents givenonly product power voltages currents generally well removed values would considered normal motor its normal prop Consider above academic exercises necessarily practical cases Table 6 Input Power Given 6-3 Prop Specific RPM RPM100001100012000 Watts44/360/S77 16 Close-up motor being tested Power motor supplied through cables connector extreme left Two test clip connections provide remote sensing precise control applied voltage Wood V-block underneath motor has rubber padding conjunction rubberbands stretched across top provide sturdy mount hold largest motors intended models NOW THERES QUICK AND EASY WAY OF ClEANING YOUR MODEL CRAFTS Super-K Model Cleaner Remaves fu Residue dirt contact1 CEJTS ClEANING TiME IN HALF Just spray model solvent wtpe soft cloth paper towel SIMPLE AS THAT Leaves craft showcase cleani eWoni hami Pahits Coverings Dries clew fast Eminates Ihe WOk cleaning model Strong Professonal Quality formula Great Model Craft Scots manes Helicopters Cleans Gently Protects delicate model DEALERS WANTED DOMESTIC & OVERSEAS WE EXPORT Hurry Have product shelves time Christmas guaranteed top seller Sugg retail $550 per gallon Contact us price structures ordering Information Also ask about other Super-K products Model Industry Ale Manufacturers & Major Brands DIstributors Model Engines Kits Radios & Accessories Super-K brand Kings RadIo Control Hobbles International 3960 West 16th Ave Hlaleah Florida 33012 Phone 305 557-2024 SS NEW * NEW * NEW BUY ECONO-PAC & SAVE WACO HKS-1GREAT LAKES TRAINER GREAT LAKES SPECIAL2T1A/2T1E PLAN$27OOppPLAN$27ttpp PG Cowl$27OOpp FG Cowl527OOpp F G Pants$25ttpp ECONO PAC$49OOpp ECOND-PACS70OOpp SAVE$600 SAVE $900 Parisian Moustique pian$17OOpp -. mixture reed valve todays ubiqui tous Cox 1/2As meetings interested modelers Brown delights producing engine pocket flash dis assembling spreading its parts out table before amazed onlookers Without too much prodding hell also demonstrate still operates just well day built Among pictures two fine examples 60 cu Brown Junior prototypes handbuilt Brown late 1931 early 1932 Both engine number A2 A5 share same basic characteristics though differ pther minor detail example like common production Browns later years engine A2 discharges its spent gases directly through tour D-shaped exhaust ports cut rear cylinder just above intake manifold engine A5 however exhaust ports concealed exhaust manifold two round threaded out lets Brown made least other engine manitolded like additional touch spark plug offset horizontally rear Incidentally both engines A2 A5 have steel pistons fitted curious ar rangement two cast iron piston rings dif ferent widthsan upper narrow com pression ring above lower very wide oil ring Note very short flared intake tubes sandcast crankcases handmade spark plugs common both early engines Max Bassetts Brown Junior number A17 manufactured Walter Hurleman Brown developed engines first pro duction tooling early summer 1932 different edge contour en gines bypass cover intake manifold indi cates parts die-stamped rather hand-formed engines A2 A5 intake tube also longer slightly larger diameter engine other 40 50 A-model Brown Juniors Hurleman said have produced before Bill Brown parted company late 1933 first have ringless precision-ground steel pistons remained hallmark qual ity model engines years afterward minor changes Hurleman continued manufacture limited quantities engine under own name until 1937 1938 Meanwhile Junior Motors Corporation organized early 1934 Bill Brown began oversee production yet another Brown Juniorthe 1934 model Bwhile still sophomore Penn State Financed Edward Roberts Philadelphia bankers son actually ran company Junior Motors turned out 50000 Brown engines before ceasing production eight years later Roberts served AMAs third president 1939 through 1942 hobbys earliest promoters Radio Control RS550S6530 good inexpensive hard-toget motor Top Flite 7 x 6 nylon Table 3 shows what happens input current input power rpm voltage varied test voltage range chosen might easily represent battery behavior just-off-charge through its useful Electrics/Kopski Continued page 95 run-down Notice dramatic power change Again static behavior shown table indication flight behavior Yes Electric noticeably hotter right after charge Ni-Cds characteristically drop initial high terminal voltage rapidly slowly decline through long plateau finally drop dramatically end-ofcharge Thats plane flies too Ive always feeling some suppliers ad vertise products performance right charge peak 3 For given propeller small change rpm representative significant change power/performance other key piece information evident Table 3 Dont treat few hundred rpm change disregard works Gas too seemingly small change tach ometer reading can indeed significant tachometer accuracy youre comparing results others Now well look implications changing prop size both diameter pitch 4 Variation prop size has signifi cant effect power performance demonstrate used favorite motors older version Astro 075 motor powered constant 70 volts propellers used Top Flite wood Labeled size assumed accurate First diameter held constant pitch varied results shown Table 4 pitch held constant 170 Model Aviation 4-STROKE ENGINE SALE COMPARE & SAVE OSFS4O8950 OSFS6O12500 OS ES 7514500 OS ES 1 20T34900 ENYA4O-4C 50 ENYA6O-4C- -14950 ENYA9O-4C 950 SAITO 308450 SAITO 40-Il9950 SAITO4510950 SAITO 90T29950 TERMS Prepald check money order Include $250 UPS avid street address Calif residents add 6% sales tax No credit cards please Allow 2 weeks delivery REDWOOD hobby Imports PO BOX 6171 SANTA ROSA CALIF 95401 Sublect stock hand Designers Builders Fine PRE-BUILT RIC Models Fire Fox Pre-Built Price $12495 Engine Size 40 cu Wing Span 521A Radio 4 Channels balsa construction Ready fine sand covpr Control surfaces hinged Has bolt-on wing HalIco landing gear ABS wheel pants mounted axels stalled Fitted canopy Instruction booklet hardware included ERO 3850 US Hwy 19 No Palm Harbor FL 33463 ECH RIC813 938-3266 Dealer Inquiries Invited Oroer Today Send check MO also accept Master Card Visa Models shipped 350 PSI carton via UPS Add $850 shipping han dling Florida residents add 5% sales tax diameter varied results shown Table 5 Tables 4 5 can easily see variations prop size can significantly affect motor power examples applied voltage held constant current increased prop size thus power increased illustrates rather graphic fashion relationship power input up point power out put increasing prop size power increase has associated dual con sequences rapid battery discharge high enough currents some risk motor brushes 5 For constant applied voltage slower motor turns higher current drain also evident Tables 4 5 Thus fast-moving plane effective propeller rpm creases due prop unloading cur rent demand drops Translation longer run ning time Conversely small prop turning high revs large slow-moving glidertype approaching static test conditions relatively higher current inefficient power utilization because prop slip ping example larger slowerturning prop speed reducer will make much better use available energy stored battery case current demand always drops flight its question much later test conditions used demon strations herein considered within reasonable range operating capability motors used except * values cases data taken very quickly higher current levels either known damaging sure did want find out other hand some data points power levels too low useful flight Nevertheless representations believed fair Again its relative performance parame ters absolute accuracy mat ters 6 The power input required motors turn given prop same rpm nearly same may surprising performance factor vividly shown accompanying graph compares power input 11 samples nine different motor types turning same 6 x 4 propeller same propeller eight 11 motors performed within ranges shown Table 6 Three motors considered removed enough trend excluded table removed inefficient power input watts 51 10000 rpm 70 11000 101 12000 information evident part propeller determines input power given rpm part motors used comparable efficiencyat least over reasonable op erating power range de signed last statement means power lost motor process doing its intended job about same motors lost power mostly form heatmore later Its interesting note the least efficient motors tested among costly middle-of-the-road occupied comparatively low-cost sleevebearing types some exceptions course efficient motors consume least power spinning given prop will run longest par ticular battery Names motors tests will supplied unless inquiier manufacturers involved 40 wing 15 25 Engines Dealers & Distributors Welcomed Phone 703 273-9593 FLYLINE MODELS INC PO Box 2136 Fairfax Virginia 22031 USA November 1983 171 magic Dragon Trainer Pre-Bui Price $9995 Engine Size 25 CU Wing Span 55 Radio 3 4 Channels balsa construction Ready fine sand cover Control surfaces hinged HalIco landing gear 5132 nose gear strut Fitted canopy Instruction booklet hardware included Five Other Models Available Send Now Free Brochure ctru~ Pre-BuIlt lrice $10995 Engine Size 40 Wing Span 52 Wing Area 614 sq Length 385/8 Weight 4 lbs Radio 4 Channels IN STOCK FOR IMMEDIATE SHIPMENT New 30 CID QUADRA $20950 New 22 CiD QUADRA $10950 Reg 22 QUADRA $10400 Brisighelia Fiywheei $12400 Rag 22 QUADRA POWER ASSEMBLY ONLY$0400 QUADRA REPAIR 000 pius parts Jim Messer ERCOUPEPLANS $2395 KIT $23995 Jim Messer TOMAHAWKPLANS $2395 KIT $25gg5 Jim Messer9BALLTRAINER PLANS 41895 KIT gggg BALSA BASSWOOD 1811 ajuesl 35% OFF Concept FLEET PLANS $2995 KIT 515995 COWL $1995 FLOATS 35115 scale core $1795 complete kit $3996 FLOATS 4W scalecores $2195 complete kit $4795 CECONiTE Product 10) OFF Sig J3 CUB KIT $12495 PLANS SUPER STEARMAN Godfrey $2895 STARDUSTER TOO h Brisighelia J-2 CUB Neiitz $2995 VOLKSPLANE Chicken Charlie $2395 COCKPIT KITS Tomahawk F4U1 Spitfire $2398 Ercoupe $2095 Stearman $2295 Citabria $2495 J3 Cub $2195 ME-lOg $2295 Fleet $2195 US Quadra FUEL TANKS16 ou $695 32 oz 5795 FIBERGLASS ARROW SHAFTS 5/10 s 32 long 0/$1000 24-Hour Service . Add $250 postage Send Bank Check Money Order JIM MESSERS QUALITY MODEL PRODUCTS 106 Valley View Dr Aliegany NY 14706 R/C Capitol offers worlds finest RC custom built-up RC scale aircraft Quarter Scala PlansEa 92495PP Quarter Scale Pertial KitsEn $95OOPP Quarter Scale Custom-Built DeluxEa $500OOPP Piper Pacer PA-20 89 Wingspan Piper Tn-Pacer PA-22 89 Wingspan DH-85 Leopard Moth 111 Wingspan DH80A Puss Moth 111 Wingspan Please send $100 self-addressed stamped envelope complete list HOBBY CAPITOL RIC ESt 1951 46 N Oak St Ventura CA 93001 805643-7616 e 642-8465 Distributors Finest Quality Built-Up A/C Aircraft Custome Built Ready-ToFly Radio Controlled Modal Airplanes Classic R/C Scale SGRAT LAK TII LT-50 Electric Motor 01 Cu Ifl equivelent gas engine displacement Send self-addressed stamped envelope catalog ap plication notes Leisure 11 Deerspringllrvine/CA 92714 readers think Im hung up small motors props allow pro vide some information bigger stuff Table 7 data limited admittedliy represents some unlikely unde sirable combinations point about props determining motor input power fur ther illustrated comparison Table 7 really stands out deserves further comment Im refer ring Astro 25 Astro 075 speed reducer both turning 9 00 rpm Remarkable isnt Whats catch None some considerations 25 operating well below its nor mal intended power level twice power level shown might say 25 being underutilized example other hand 075 system being very well used Its lighter weight lower cost could reasonably pushed mOch higher normal power capability 25 Whatever prop dictating power demand point Im making get Part 4 batteries youll see energy tanks must con sidered part big picturethe total Electric system picturewhere choice system component sort team choice Translation want run 9 x 6 8000 other motor/prop/rpm combination fly some plane some specific duration battery because practicalities cell size number cells charging considerations 2 Motor propeller plane efficiency data examples given part have nominal operating condi tions motor propeller mean operating conditions would representative good fly ing power levels Putting yet another way would conditions reasonably good efficiency motors props presented used suitable plane Efficiency power output divided power input always number less meaning get less out put difference wasted power mentioned earlier Another point made earlier electrical power put motor easily measured simply product motor input volt age wattage current Power outputrelated work done motor its propeller moving both air planeis easily measured Anyway efficiency curve has shape bit like hook clothes hanger maybe like climb level-off dive roller coaster means some power range maximizing efficiencythe place percentage power lost least information Ive seen peak actually rounded usually represents rather broad range good power utilization 172 Model Aviation motor/prop maY primary con sideration Power Soar New Heights other words dont have oper ating exactly very peak impossible maintain anyway enjoy lot great flying Far either side broad max imum region however operating ex tremes efficiency can terrible flight will also terrible what extremes low ends efficiency curve can come end low power levels ratio output power input power small because example much input power goes kinds losses shown Table Ithe no prop power used overcome friction etc Thus small amount power de livered prop may comparable less lost would almost al ways no-flight condition anyway saw power region very low wattage region indeed other end efficiency curve very high input power levels motor losses rise very rapidly due example heating area operation cur rent input very high such too much voltage applied too large prop used power lost heat rises rapidly because power product current times current times resistance commonly called squared R' losses resistance armature windings brush-tocommutator contact resistance brush material brush connection resistance big driver current times itself Thus under such conditions more current input lower lower percentage power output ef ficiency curve drops off sooner later motor may go belly up excess ive brush heat heating concern Ive alluded often comes few words motors currently use simply adaptations some readily available often imported standard low cost unit intended con sumer applications nothing wrong this allows variety low cost what can see appli cation model use probably tasks motors far other intended ap plication application feel putting motors past limits design intent experience first mani festation brush damage very high currents Anyway more motors becoming available have much better behavior regard other things parts continuing Elec tric evolution Later get planes stallations well look some actual exam ples operation some guidelines help assure longevity investment along lots enjoyable flying fun now should clear motor prop independent plane What can too much motor bench static may case air providing plane moves out quickly allowing prop unload As mentioned earlier motor turning small November 1983 173 prop fast slowly-moving glider-type inefficient potentially bad-for-themotor situation Now let describe ex ample thats similar other direc tion Ive twice occasion help someone ARF Kraft Shoestring tractive planes 05-sized motor six cells 06 Ah size nylon props 8 x 6 planes just sorta mushed along studying situation respect weight area etc seemed really should fly better changed prop nylon 7 x 6 did trick motor turned up faster expected drew less current motor-prop-plane combination now much better fact plane much fun fly Simple huh does know what may have realized clue solution came three paragraphs earlierlook back see Admittedly above discussions simplifications incomplete theres involved motor/prop/plane performance discussed far think weve gone far enough get general ideathat theres variety motors avail able work quite well prop choice power closely related good results efficient motor/plane/prop combination thats needed Well al subject must covered before can look what works well together WS 54 29 35 ENGINtS 3 CHANNEL THE BEGINNERS KITTEN AND EXPERTS TIGER Revolutionary snap-on wing eliminates bolts rnbber bands complete kit $54 95 dealer direct GEMINI MODELS INC PO Bn 1168 Pasc NJ 07055 topic comes up next month Batteries Remember promised two things basics things work intend keep commitment So far weve dealing mostly first part promise will seriously pursue Elec trics basics given will sooner later directly contribute success own Electric design choices part making guy mentioned Part 2 guy understands basics knows what to worksthe guy whos 'got together Electrics closing note first four parts series will have written before Part 1 reaches readers expect installment will raise questions Despite good inten tions know some things will overlooked some things will unclear can welcome critic regard Perhaps most-asked questions can collected answers presented read wrap-up installment meantime will endeavor responsive individuals expediently possible Please direct questions SASE author Bob Kopski 25 West End Dr Lansdale PA 19446 SAFE FLYING IS NO ACCIDENT SAM Champs/Mathews Continued page 81 really means something SAM types host chapter SAM No Contest Director Jim Thomas obviously done homework example fact no sooner mentioned nice would someone water down dusty access road water truck arrived did just process repeated two three times daily Although no hookups available campers motor homes contest site sev eral self-contained vehicles well tenters campers stayed ovemight site Motel ar rangements well-handled Tanya Baird Chamber Commerce office available room LaJunta reserved mid-April attendees found accommodations nearby towns Rates very reasonable Ad ditional rooms available Otero Junior Col lege stayed reported clean air-conditioned facilities lots bull ses sions progress times lounge area concessionaire provided food drink flying fieldagain very reasonable prices However breakfast Laiunta proved bit hassle sudden influx hungry modelers demanding breakfast 600 am overtaxed staffs local restaurants making rather slow service fact some eateries didnt open until 700 am seems real crux problem contest manage ments decision start flying 800 rather originally-announced time 900 am scheduling change made order get competition over hour earlierto get out heat As matter fact since LaJunta far eastern edge Mountain timezone flying could have scheduled start 600 am contest day could have ended early 300 pm Go Upty Up-Up Problems effect high altitude engine power glide models didnt seem severe anticipated Although power-loss certainly factor major problems seemed i/A reed-valve engines Texaco event Climbouts certainly lower slower peculiar distribution lift atmosphere real oddity saw As repeatedly observed lift existed strata model would riding rather large boomer another plane immediately below above would downer Ther mal pattems much like seen Lake Charles LA accustomed finding Great Plains 174 Model Aviation product can recommendSUPER HAND SAN DER Dealers & Distributors Wanted confidenceHOBBIESTSee Hobby Dealer Call Art Gross Enterprises HOBBY DEALERCa// Distributor 06/743-9332 ART GROSS ENTERPRISES 12516 MAPLEWOOD AVE EDMONDS WA 98020 DUAL PERSONAUTY TRAINER GEENIS BEAUTIFULI SUPER CHAMP [F6T\F1 Invited Liti IjI.u Inc Dealer inquiries High pert onnante model engine connecting rods connecting rods made tha beat materials available designed give long service eliminate rod breakage modern high-Peef mance model engines Used leading aircraft boat car racers hobbyists Rods available popular model engines Look RPM new innovative products wish proven performance records Richardson Precision Machining Inc 5070 Golden Dr San Jose cA 5612914061 2S7-7068
Edition: Model Aviation - 1983/11
Page Numbers: 93, 94, 95, 170, 171, 172, 173, 174
This authors testing setup evaluation motors props results shown tables discussed text power supply fully adjustable zero 30 volts up 20 amperes two digital readouts motor voltage current analog meter tachometer optical pickup remotely located under motor mount Light source also remotely located Photos author THE FIRST INSTALLMENT series September issue described some pros cons electric-powered models last month covered motors use Some basic aspects motors de scribed practical considerations covered Earlier asked have faith read daringly onward remind because realize subject part may appear both simple some strange others However think some up coming information will surprising interesting manyand perhaps little confusing ditficult others first reading still others some what fol lows may downright boring seem totally irrelevant taken alone section however combined ether parts series will provide very intimate overall feel exactly what \Ki O iOE ra popellor rave electricpowered models yoi re new Electrics authors test results may astound second reading may required fully grasp some points thai made that1s what takes suggest Part 3 November 1983 93 goes motor battery pro peller given planeand affect flight results get other words series continues will come together' encourage un daunted continuance series Im sure will find worthwhile presentation seems too slow 80 70 60 -50 40 -8 tedious remern ber introduction Electricson installment plan Its necessarily easy installment plan either read write Hox ever maintain subject can generally simple oc t V 0 0 0 ----V e Lu 0 0 0 0 0 -I C V e 0 V C 0 0 RPM X 1000 91011 SC V0 certainly successful though neces sadly short Perhaps some readers have disap pointments Electrics just because some details made light glossed over elsewhere Thats Model Avi ation has planned seriesto make sure adequate introductory treatment such anyone wants can very successful Electric flier theres some useful stuff Gas guys honest well-intended series cannot complete detail-perfect several reasons dont know everything Another Im trying se lect meaningful useful offer ings consistent limitations pub lication space presentation time can fact best can can criticautomaticallyby asking questions 1 Propellers power Now Chave seen some Electric models Part have some introductory insight motors Part 2 could wondering what business concerning power heating performance about Lets look what happens motor required its thingturn prop power plane leading suppliers Electric flight systems provide instructions regarding choice model size weight suit able propellers things will also addressed another part series meantime get good feel motor operation propellers power lets look things static environment ie bench rather flight experience excellent correlation tween what observe bench what experience air A Power inputno prop Electrical power product electric potential volts electric current amps case motor input power motor terminal voltage times motor terminal input current amperage product V x power watts power comes frm energy 12131415 tank battery tank specific size can deliver its fill Part 4 will cover batteries detail discuss much tanks' can deliver Now however going get feel just Shown motor input power various motor speeds rpm 11 samples nine different motor types swinging Cox 6-4 gray prop Note different symbol 11 motors Connect like symbols form smooth performance curves through various speeds Note generally tight clusters data points throughout range test 94 Model Aviation Table 1 Typical Motor Power InputNo Prop MotorVoltsAmpsWatts Astro 0560075450 p/n 210770078546 80081648 90084756 Leisure LT-5050119595 Pattern Wind60124744 7013091 Mabuchi5011859 RS540S65276013078 70146102 80153122 Table 2 Performance Variation Various Same Size Props Propeller 64AmpsWatts Top Flite Nylon1168113300 Top Flite Wood13393112700 Cox Gray155*10912200 Table 3 Typical Motor/Propeller Performance Voltage Variation VoltsAmpsWattsRPM 60795488000 65905598550 70100709050 75110839600 801219710000 8513011110500 133 120 110 100 90 much fuel used motors next month youll have appreciation Part 4 As mentioned earlier motor running no prop draws small amount current sufficient overcome losses due friction other things illustrate sev eral examples shown Table measurements made using test setup pictured Notice something particular about data Table example motor current increase large crease voltage caused will case prop measurements tests made using convenient adjustable power supply exactly same re sults would occur motor bat tery interested power supply pictured capable up 30 volts 20 amps has remote voltage sense assure correct voltage motor terminals Also has adjustable current limit dont have accident during some zealous data run power capa bility may sound impressive believe expect need capability near future point want make special note has experience Ive told same Electric flight system suppliers performance production flight motors varies about plus-or-minus 10% As youll also see props also vary greatly load present motor battery course measurement motor performance has instrumentation accuracy associated Thus rea sons apparent differences Electric flight experience can occur Em noting now just case anyone reading has has read about different results B Power inputwith props ifl tables various motor performance mea surements different props ahown Whats mportant absoLve ac curacy relative performances -i particuiar notice bow rapidly input power changes tbattery voltage dra matic eFfect piop size can hae youll see important use right prop temptation just stick bigger prop add another cell may have carefully con sidered What seems like small change may fact either present unbearable load motor lest cause decline power system efficiency Remember static demonstrations motor/prop moving forward actual flying condi tions aircraft speed etc can have signifi cant influence data 1 All propellers same size necessarily created equal demonstrate ran Leisure LT-50 Pattern Wind very nicely-made motor three different 6 X 4 props applied voltage held constant 70 volts much like battery would hold nearly-constant voltage Table 2 lists resulting current drain input power rpm Notice wide variation power input roughly translates about same variation power output flight per formance might inclined say prop better prop remember dont get something nothing output performance input power means faster battery dis charge shorter flight timealthough increased flight performance may very well worth depending plane want fly some simi larity running engine full bore vs half throttle latter goes longer tank fuel Does Cox 6 x 4 gray fly aerobatic Jack Rabbit hotter Top Flight 6 x 4 nylon betcha buddy gives shorter flight too 2 A small change voltage makes big change performance demon strate propped Mabuchi Continued page 170 November 1983 95 Table 4 Effect Propeller Pitch Motor Input Power PropAmpsWattsRPM 8-468487950 8-580567550 8-696677000 8-8117826200 Table 5 Effect Prop Diameter Motor Input Power PropAmpsWattsRPM 6-437269000 7-450358400 8-469487900 Table 7 Some Larger Motor/Prop/Power Demonstrations MotorPropRPMPower Astro 259-6 wood700086 watts Astro 109-6 wood700090 watts Astro 075* *9-6 wood700080 watts Astro 259-6 wood8000126 watts Astro 075* *9-6 wood8000115 watts Astro 2512-6 wood5100115 watts Astrol5**12-6wood510096watts Now 1 ** means motors used matching speed reducers 2 In cases motor clearly over-propped operating conditions carefully controlled no risk motor involved 3 No voltages currents givenonly product power voltages currents generally well removed values would considered normal motor its normal prop Consider above academic exercises necessarily practical cases Table 6 Input Power Given 6-3 Prop Specific RPM RPM100001100012000 Watts44/360/S77 16 Close-up motor being tested Power motor supplied through cables connector extreme left Two test clip connections provide remote sensing precise control applied voltage Wood V-block underneath motor has rubber padding conjunction rubberbands stretched across top provide sturdy mount hold largest motors intended models NOW THERES QUICK AND EASY WAY OF ClEANING YOUR MODEL CRAFTS Super-K Model Cleaner Remaves fu Residue dirt contact1 CEJTS ClEANING TiME IN HALF Just spray model solvent wtpe soft cloth paper towel SIMPLE AS THAT Leaves craft showcase cleani eWoni hami Pahits Coverings Dries clew fast Eminates Ihe WOk cleaning model Strong Professonal Quality formula Great Model Craft Scots manes Helicopters Cleans Gently Protects delicate model DEALERS WANTED DOMESTIC & OVERSEAS WE EXPORT Hurry Have product shelves time Christmas guaranteed top seller Sugg retail $550 per gallon Contact us price structures ordering Information Also ask about other Super-K products Model Industry Ale Manufacturers & Major Brands DIstributors Model Engines Kits Radios & Accessories Super-K brand Kings RadIo Control Hobbles International 3960 West 16th Ave Hlaleah Florida 33012 Phone 305 557-2024 SS NEW * NEW * NEW BUY ECONO-PAC & SAVE WACO HKS-1GREAT LAKES TRAINER GREAT LAKES SPECIAL2T1A/2T1E PLAN$27OOppPLAN$27ttpp PG Cowl$27OOpp FG Cowl527OOpp F G Pants$25ttpp ECONO PAC$49OOpp ECOND-PACS70OOpp SAVE$600 SAVE $900 Parisian Moustique pian$17OOpp -. mixture reed valve todays ubiqui tous Cox 1/2As meetings interested modelers Brown delights producing engine pocket flash dis assembling spreading its parts out table before amazed onlookers Without too much prodding hell also demonstrate still operates just well day built Among pictures two fine examples 60 cu Brown Junior prototypes handbuilt Brown late 1931 early 1932 Both engine number A2 A5 share same basic characteristics though differ pther minor detail example like common production Browns later years engine A2 discharges its spent gases directly through tour D-shaped exhaust ports cut rear cylinder just above intake manifold engine A5 however exhaust ports concealed exhaust manifold two round threaded out lets Brown made least other engine manitolded like additional touch spark plug offset horizontally rear Incidentally both engines A2 A5 have steel pistons fitted curious ar rangement two cast iron piston rings dif ferent widthsan upper narrow com pression ring above lower very wide oil ring Note very short flared intake tubes sandcast crankcases handmade spark plugs common both early engines Max Bassetts Brown Junior number A17 manufactured Walter Hurleman Brown developed engines first pro duction tooling early summer 1932 different edge contour en gines bypass cover intake manifold indi cates parts die-stamped rather hand-formed engines A2 A5 intake tube also longer slightly larger diameter engine other 40 50 A-model Brown Juniors Hurleman said have produced before Bill Brown parted company late 1933 first have ringless precision-ground steel pistons remained hallmark qual ity model engines years afterward minor changes Hurleman continued manufacture limited quantities engine under own name until 1937 1938 Meanwhile Junior Motors Corporation organized early 1934 Bill Brown began oversee production yet another Brown Juniorthe 1934 model Bwhile still sophomore Penn State Financed Edward Roberts Philadelphia bankers son actually ran company Junior Motors turned out 50000 Brown engines before ceasing production eight years later Roberts served AMAs third president 1939 through 1942 hobbys earliest promoters Radio Control RS550S6530 good inexpensive hard-toget motor Top Flite 7 x 6 nylon Table 3 shows what happens input current input power rpm voltage varied test voltage range chosen might easily represent battery behavior just-off-charge through its useful Electrics/Kopski Continued page 95 run-down Notice dramatic power change Again static behavior shown table indication flight behavior Yes Electric noticeably hotter right after charge Ni-Cds characteristically drop initial high terminal voltage rapidly slowly decline through long plateau finally drop dramatically end-ofcharge Thats plane flies too Ive always feeling some suppliers ad vertise products performance right charge peak 3 For given propeller small change rpm representative significant change power/performance other key piece information evident Table 3 Dont treat few hundred rpm change disregard works Gas too seemingly small change tach ometer reading can indeed significant tachometer accuracy youre comparing results others Now well look implications changing prop size both diameter pitch 4 Variation prop size has signifi cant effect power performance demonstrate used favorite motors older version Astro 075 motor powered constant 70 volts propellers used Top Flite wood Labeled size assumed accurate First diameter held constant pitch varied results shown Table 4 pitch held constant 170 Model Aviation 4-STROKE ENGINE SALE COMPARE & SAVE OSFS4O8950 OSFS6O12500 OS ES 7514500 OS ES 1 20T34900 ENYA4O-4C 50 ENYA6O-4C- -14950 ENYA9O-4C 950 SAITO 308450 SAITO 40-Il9950 SAITO4510950 SAITO 90T29950 TERMS Prepald check money order Include $250 UPS avid street address Calif residents add 6% sales tax No credit cards please Allow 2 weeks delivery REDWOOD hobby Imports PO BOX 6171 SANTA ROSA CALIF 95401 Sublect stock hand Designers Builders Fine PRE-BUILT RIC Models Fire Fox Pre-Built Price $12495 Engine Size 40 cu Wing Span 521A Radio 4 Channels balsa construction Ready fine sand covpr Control surfaces hinged Has bolt-on wing HalIco landing gear ABS wheel pants mounted axels stalled Fitted canopy Instruction booklet hardware included ERO 3850 US Hwy 19 No Palm Harbor FL 33463 ECH RIC813 938-3266 Dealer Inquiries Invited Oroer Today Send check MO also accept Master Card Visa Models shipped 350 PSI carton via UPS Add $850 shipping han dling Florida residents add 5% sales tax diameter varied results shown Table 5 Tables 4 5 can easily see variations prop size can significantly affect motor power examples applied voltage held constant current increased prop size thus power increased illustrates rather graphic fashion relationship power input up point power out put increasing prop size power increase has associated dual con sequences rapid battery discharge high enough currents some risk motor brushes 5 For constant applied voltage slower motor turns higher current drain also evident Tables 4 5 Thus fast-moving plane effective propeller rpm creases due prop unloading cur rent demand drops Translation longer run ning time Conversely small prop turning high revs large slow-moving glidertype approaching static test conditions relatively higher current inefficient power utilization because prop slip ping example larger slowerturning prop speed reducer will make much better use available energy stored battery case current demand always drops flight its question much later test conditions used demon strations herein considered within reasonable range operating capability motors used except * values cases data taken very quickly higher current levels either known damaging sure did want find out other hand some data points power levels too low useful flight Nevertheless representations believed fair Again its relative performance parame ters absolute accuracy mat ters 6 The power input required motors turn given prop same rpm nearly same may surprising performance factor vividly shown accompanying graph compares power input 11 samples nine different motor types turning same 6 x 4 propeller same propeller eight 11 motors performed within ranges shown Table 6 Three motors considered removed enough trend excluded table removed inefficient power input watts 51 10000 rpm 70 11000 101 12000 information evident part propeller determines input power given rpm part motors used comparable efficiencyat least over reasonable op erating power range de signed last statement means power lost motor process doing its intended job about same motors lost power mostly form heatmore later Its interesting note the least efficient motors tested among costly middle-of-the-road occupied comparatively low-cost sleevebearing types some exceptions course efficient motors consume least power spinning given prop will run longest par ticular battery Names motors tests will supplied unless inquiier manufacturers involved 40 wing 15 25 Engines Dealers & Distributors Welcomed Phone 703 273-9593 FLYLINE MODELS INC PO Box 2136 Fairfax Virginia 22031 USA November 1983 171 magic Dragon Trainer Pre-Bui Price $9995 Engine Size 25 CU Wing Span 55 Radio 3 4 Channels balsa construction Ready fine sand cover Control surfaces hinged HalIco landing gear 5132 nose gear strut Fitted canopy Instruction booklet hardware included Five Other Models Available Send Now Free Brochure ctru~ Pre-BuIlt lrice $10995 Engine Size 40 Wing Span 52 Wing Area 614 sq Length 385/8 Weight 4 lbs Radio 4 Channels IN STOCK FOR IMMEDIATE SHIPMENT New 30 CID QUADRA $20950 New 22 CiD QUADRA $10950 Reg 22 QUADRA $10400 Brisighelia Fiywheei $12400 Rag 22 QUADRA POWER ASSEMBLY ONLY$0400 QUADRA REPAIR 000 pius parts Jim Messer ERCOUPEPLANS $2395 KIT $23995 Jim Messer TOMAHAWKPLANS $2395 KIT $25gg5 Jim Messer9BALLTRAINER PLANS 41895 KIT gggg BALSA BASSWOOD 1811 ajuesl 35% OFF Concept FLEET PLANS $2995 KIT 515995 COWL $1995 FLOATS 35115 scale core $1795 complete kit $3996 FLOATS 4W scalecores $2195 complete kit $4795 CECONiTE Product 10) OFF Sig J3 CUB KIT $12495 PLANS SUPER STEARMAN Godfrey $2895 STARDUSTER TOO h Brisighelia J-2 CUB Neiitz $2995 VOLKSPLANE Chicken Charlie $2395 COCKPIT KITS Tomahawk F4U1 Spitfire $2398 Ercoupe $2095 Stearman $2295 Citabria $2495 J3 Cub $2195 ME-lOg $2295 Fleet $2195 US Quadra FUEL TANKS16 ou $695 32 oz 5795 FIBERGLASS ARROW SHAFTS 5/10 s 32 long 0/$1000 24-Hour Service . Add $250 postage Send Bank Check Money Order JIM MESSERS QUALITY MODEL PRODUCTS 106 Valley View Dr Aliegany NY 14706 R/C Capitol offers worlds finest RC custom built-up RC scale aircraft Quarter Scala PlansEa 92495PP Quarter Scale Pertial KitsEn $95OOPP Quarter Scale Custom-Built DeluxEa $500OOPP Piper Pacer PA-20 89 Wingspan Piper Tn-Pacer PA-22 89 Wingspan DH-85 Leopard Moth 111 Wingspan DH80A Puss Moth 111 Wingspan Please send $100 self-addressed stamped envelope complete list HOBBY CAPITOL RIC ESt 1951 46 N Oak St Ventura CA 93001 805643-7616 e 642-8465 Distributors Finest Quality Built-Up A/C Aircraft Custome Built Ready-ToFly Radio Controlled Modal Airplanes Classic R/C Scale SGRAT LAK TII LT-50 Electric Motor 01 Cu Ifl equivelent gas engine displacement Send self-addressed stamped envelope catalog ap plication notes Leisure 11 Deerspringllrvine/CA 92714 readers think Im hung up small motors props allow pro vide some information bigger stuff Table 7 data limited admittedliy represents some unlikely unde sirable combinations point about props determining motor input power fur ther illustrated comparison Table 7 really stands out deserves further comment Im refer ring Astro 25 Astro 075 speed reducer both turning 9 00 rpm Remarkable isnt Whats catch None some considerations 25 operating well below its nor mal intended power level twice power level shown might say 25 being underutilized example other hand 075 system being very well used Its lighter weight lower cost could reasonably pushed mOch higher normal power capability 25 Whatever prop dictating power demand point Im making get Part 4 batteries youll see energy tanks must con sidered part big picturethe total Electric system picturewhere choice system component sort team choice Translation want run 9 x 6 8000 other motor/prop/rpm combination fly some plane some specific duration battery because practicalities cell size number cells charging considerations 2 Motor propeller plane efficiency data examples given part have nominal operating condi tions motor propeller mean operating conditions would representative good fly ing power levels Putting yet another way would conditions reasonably good efficiency motors props presented used suitable plane Efficiency power output divided power input always number less meaning get less out put difference wasted power mentioned earlier Another point made earlier electrical power put motor easily measured simply product motor input volt age wattage current Power outputrelated work done motor its propeller moving both air planeis easily measured Anyway efficiency curve has shape bit like hook clothes hanger maybe like climb level-off dive roller coaster means some power range maximizing efficiencythe place percentage power lost least information Ive seen peak actually rounded usually represents rather broad range good power utilization 172 Model Aviation motor/prop maY primary con sideration Power Soar New Heights other words dont have oper ating exactly very peak impossible maintain anyway enjoy lot great flying Far either side broad max imum region however operating ex tremes efficiency can terrible flight will also terrible what extremes low ends efficiency curve can come end low power levels ratio output power input power small because example much input power goes kinds losses shown Table Ithe no prop power used overcome friction etc Thus small amount power de livered prop may comparable less lost would almost al ways no-flight condition anyway saw power region very low wattage region indeed other end efficiency curve very high input power levels motor losses rise very rapidly due example heating area operation cur rent input very high such too much voltage applied too large prop used power lost heat rises rapidly because power product current times current times resistance commonly called squared R' losses resistance armature windings brush-tocommutator contact resistance brush material brush connection resistance big driver current times itself Thus under such conditions more current input lower lower percentage power output ef ficiency curve drops off sooner later motor may go belly up excess ive brush heat heating concern Ive alluded often comes few words motors currently use simply adaptations some readily available often imported standard low cost unit intended con sumer applications nothing wrong this allows variety low cost what can see appli cation model use probably tasks motors far other intended ap plication application feel putting motors past limits design intent experience first mani festation brush damage very high currents Anyway more motors becoming available have much better behavior regard other things parts continuing Elec tric evolution Later get planes stallations well look some actual exam ples operation some guidelines help assure longevity investment along lots enjoyable flying fun now should clear motor prop independent plane What can too much motor bench static may case air providing plane moves out quickly allowing prop unload As mentioned earlier motor turning small November 1983 173 prop fast slowly-moving glider-type inefficient potentially bad-for-themotor situation Now let describe ex ample thats similar other direc tion Ive twice occasion help someone ARF Kraft Shoestring tractive planes 05-sized motor six cells 06 Ah size nylon props 8 x 6 planes just sorta mushed along studying situation respect weight area etc seemed really should fly better changed prop nylon 7 x 6 did trick motor turned up faster expected drew less current motor-prop-plane combination now much better fact plane much fun fly Simple huh does know what may have realized clue solution came three paragraphs earlierlook back see Admittedly above discussions simplifications incomplete theres involved motor/prop/plane performance discussed far think weve gone far enough get general ideathat theres variety motors avail able work quite well prop choice power closely related good results efficient motor/plane/prop combination thats needed Well al subject must covered before can look what works well together WS 54 29 35 ENGINtS 3 CHANNEL THE BEGINNERS KITTEN AND EXPERTS TIGER Revolutionary snap-on wing eliminates bolts rnbber bands complete kit $54 95 dealer direct GEMINI MODELS INC PO Bn 1168 Pasc NJ 07055 topic comes up next month Batteries Remember promised two things basics things work intend keep commitment So far weve dealing mostly first part promise will seriously pursue Elec trics basics given will sooner later directly contribute success own Electric design choices part making guy mentioned Part 2 guy understands basics knows what to worksthe guy whos 'got together Electrics closing note first four parts series will have written before Part 1 reaches readers expect installment will raise questions Despite good inten tions know some things will overlooked some things will unclear can welcome critic regard Perhaps most-asked questions can collected answers presented read wrap-up installment meantime will endeavor responsive individuals expediently possible Please direct questions SASE author Bob Kopski 25 West End Dr Lansdale PA 19446 SAFE FLYING IS NO ACCIDENT SAM Champs/Mathews Continued page 81 really means something SAM types host chapter SAM No Contest Director Jim Thomas obviously done homework example fact no sooner mentioned nice would someone water down dusty access road water truck arrived did just process repeated two three times daily Although no hookups available campers motor homes contest site sev eral self-contained vehicles well tenters campers stayed ovemight site Motel ar rangements well-handled Tanya Baird Chamber Commerce office available room LaJunta reserved mid-April attendees found accommodations nearby towns Rates very reasonable Ad ditional rooms available Otero Junior Col lege stayed reported clean air-conditioned facilities lots bull ses sions progress times lounge area concessionaire provided food drink flying fieldagain very reasonable prices However breakfast Laiunta proved bit hassle sudden influx hungry modelers demanding breakfast 600 am overtaxed staffs local restaurants making rather slow service fact some eateries didnt open until 700 am seems real crux problem contest manage ments decision start flying 800 rather originally-announced time 900 am scheduling change made order get competition over hour earlierto get out heat As matter fact since LaJunta far eastern edge Mountain timezone flying could have scheduled start 600 am contest day could have ended early 300 pm Go Upty Up-Up Problems effect high altitude engine power glide models didnt seem severe anticipated Although power-loss certainly factor major problems seemed i/A reed-valve engines Texaco event Climbouts certainly lower slower peculiar distribution lift atmosphere real oddity saw As repeatedly observed lift existed strata model would riding rather large boomer another plane immediately below above would downer Ther mal pattems much like seen Lake Charles LA accustomed finding Great Plains 174 Model Aviation product can recommendSUPER HAND SAN DER Dealers & Distributors Wanted confidenceHOBBIESTSee Hobby Dealer Call Art Gross Enterprises HOBBY DEALERCa// Distributor 06/743-9332 ART GROSS ENTERPRISES 12516 MAPLEWOOD AVE EDMONDS WA 98020 DUAL PERSONAUTY TRAINER GEENIS BEAUTIFULI SUPER CHAMP [F6T\F1 Invited Liti IjI.u Inc Dealer inquiries High pert onnante model engine connecting rods connecting rods made tha beat materials available designed give long service eliminate rod breakage modern high-Peef mance model engines Used leading aircraft boat car racers hobbyists Rods available popular model engines Look RPM new innovative products wish proven performance records Richardson Precision Machining Inc 5070 Golden Dr San Jose cA 5612914061 2S7-7068
Edition: Model Aviation - 1983/11
Page Numbers: 93, 94, 95, 170, 171, 172, 173, 174
This authors testing setup evaluation motors props results shown tables discussed text power supply fully adjustable zero 30 volts up 20 amperes two digital readouts motor voltage current analog meter tachometer optical pickup remotely located under motor mount Light source also remotely located Photos author THE FIRST INSTALLMENT series September issue described some pros cons electric-powered models last month covered motors use Some basic aspects motors de scribed practical considerations covered Earlier asked have faith read daringly onward remind because realize subject part may appear both simple some strange others However think some up coming information will surprising interesting manyand perhaps little confusing ditficult others first reading still others some what fol lows may downright boring seem totally irrelevant taken alone section however combined ether parts series will provide very intimate overall feel exactly what \Ki O iOE ra popellor rave electricpowered models yoi re new Electrics authors test results may astound second reading may required fully grasp some points thai made that1s what takes suggest Part 3 November 1983 93 goes motor battery pro peller given planeand affect flight results get other words series continues will come together' encourage un daunted continuance series Im sure will find worthwhile presentation seems too slow 80 70 60 -50 40 -8 tedious remern ber introduction Electricson installment plan Its necessarily easy installment plan either read write Hox ever maintain subject can generally simple oc t V 0 0 0 ----V e Lu 0 0 0 0 0 -I C V e 0 V C 0 0 RPM X 1000 91011 SC V0 certainly successful though neces sadly short Perhaps some readers have disap pointments Electrics just because some details made light glossed over elsewhere Thats Model Avi ation has planned seriesto make sure adequate introductory treatment such anyone wants can very successful Electric flier theres some useful stuff Gas guys honest well-intended series cannot complete detail-perfect several reasons dont know everything Another Im trying se lect meaningful useful offer ings consistent limitations pub lication space presentation time can fact best can can criticautomaticallyby asking questions 1 Propellers power Now Chave seen some Electric models Part have some introductory insight motors Part 2 could wondering what business concerning power heating performance about Lets look what happens motor required its thingturn prop power plane leading suppliers Electric flight systems provide instructions regarding choice model size weight suit able propellers things will also addressed another part series meantime get good feel motor operation propellers power lets look things static environment ie bench rather flight experience excellent correlation tween what observe bench what experience air A Power inputno prop Electrical power product electric potential volts electric current amps case motor input power motor terminal voltage times motor terminal input current amperage product V x power watts power comes frm energy 12131415 tank battery tank specific size can deliver its fill Part 4 will cover batteries detail discuss much tanks' can deliver Now however going get feel just Shown motor input power various motor speeds rpm 11 samples nine different motor types swinging Cox 6-4 gray prop Note different symbol 11 motors Connect like symbols form smooth performance curves through various speeds Note generally tight clusters data points throughout range test 94 Model Aviation Table 1 Typical Motor Power InputNo Prop MotorVoltsAmpsWatts Astro 0560075450 p/n 210770078546 80081648 90084756 Leisure LT-5050119595 Pattern Wind60124744 7013091 Mabuchi5011859 RS540S65276013078 70146102 80153122 Table 2 Performance Variation Various Same Size Props Propeller 64AmpsWatts Top Flite Nylon1168113300 Top Flite Wood13393112700 Cox Gray155*10912200 Table 3 Typical Motor/Propeller Performance Voltage Variation VoltsAmpsWattsRPM 60795488000 65905598550 70100709050 75110839600 801219710000 8513011110500 133 120 110 100 90 much fuel used motors next month youll have appreciation Part 4 As mentioned earlier motor running no prop draws small amount current sufficient overcome losses due friction other things illustrate sev eral examples shown Table measurements made using test setup pictured Notice something particular about data Table example motor current increase large crease voltage caused will case prop measurements tests made using convenient adjustable power supply exactly same re sults would occur motor bat tery interested power supply pictured capable up 30 volts 20 amps has remote voltage sense assure correct voltage motor terminals Also has adjustable current limit dont have accident during some zealous data run power capa bility may sound impressive believe expect need capability near future point want make special note has experience Ive told same Electric flight system suppliers performance production flight motors varies about plus-or-minus 10% As youll also see props also vary greatly load present motor battery course measurement motor performance has instrumentation accuracy associated Thus rea sons apparent differences Electric flight experience can occur Em noting now just case anyone reading has has read about different results B Power inputwith props ifl tables various motor performance mea surements different props ahown Whats mportant absoLve ac curacy relative performances -i particuiar notice bow rapidly input power changes tbattery voltage dra matic eFfect piop size can hae youll see important use right prop temptation just stick bigger prop add another cell may have carefully con sidered What seems like small change may fact either present unbearable load motor lest cause decline power system efficiency Remember static demonstrations motor/prop moving forward actual flying condi tions aircraft speed etc can have signifi cant influence data 1 All propellers same size necessarily created equal demonstrate ran Leisure LT-50 Pattern Wind very nicely-made motor three different 6 X 4 props applied voltage held constant 70 volts much like battery would hold nearly-constant voltage Table 2 lists resulting current drain input power rpm Notice wide variation power input roughly translates about same variation power output flight per formance might inclined say prop better prop remember dont get something nothing output performance input power means faster battery dis charge shorter flight timealthough increased flight performance may very well worth depending plane want fly some simi larity running engine full bore vs half throttle latter goes longer tank fuel Does Cox 6 x 4 gray fly aerobatic Jack Rabbit hotter Top Flight 6 x 4 nylon betcha buddy gives shorter flight too 2 A small change voltage makes big change performance demon strate propped Mabuchi Continued page 170 November 1983 95 Table 4 Effect Propeller Pitch Motor Input Power PropAmpsWattsRPM 8-468487950 8-580567550 8-696677000 8-8117826200 Table 5 Effect Prop Diameter Motor Input Power PropAmpsWattsRPM 6-437269000 7-450358400 8-469487900 Table 7 Some Larger Motor/Prop/Power Demonstrations MotorPropRPMPower Astro 259-6 wood700086 watts Astro 109-6 wood700090 watts Astro 075* *9-6 wood700080 watts Astro 259-6 wood8000126 watts Astro 075* *9-6 wood8000115 watts Astro 2512-6 wood5100115 watts Astrol5**12-6wood510096watts Now 1 ** means motors used matching speed reducers 2 In cases motor clearly over-propped operating conditions carefully controlled no risk motor involved 3 No voltages currents givenonly product power voltages currents generally well removed values would considered normal motor its normal prop Consider above academic exercises necessarily practical cases Table 6 Input Power Given 6-3 Prop Specific RPM RPM100001100012000 Watts44/360/S77 16 Close-up motor being tested Power motor supplied through cables connector extreme left Two test clip connections provide remote sensing precise control applied voltage Wood V-block underneath motor has rubber padding conjunction rubberbands stretched across top provide sturdy mount hold largest motors intended models NOW THERES QUICK AND EASY WAY OF ClEANING YOUR MODEL CRAFTS Super-K Model Cleaner Remaves fu Residue dirt contact1 CEJTS ClEANING TiME IN HALF Just spray model solvent wtpe soft cloth paper towel SIMPLE AS THAT Leaves craft showcase cleani eWoni hami Pahits Coverings Dries clew fast Eminates Ihe WOk cleaning model Strong Professonal Quality formula Great Model Craft Scots manes Helicopters Cleans Gently Protects delicate model DEALERS WANTED DOMESTIC & OVERSEAS WE EXPORT Hurry Have product shelves time Christmas guaranteed top seller Sugg retail $550 per gallon Contact us price structures ordering Information Also ask about other Super-K products Model Industry Ale Manufacturers & Major Brands DIstributors Model Engines Kits Radios & Accessories Super-K brand Kings RadIo Control Hobbles International 3960 West 16th Ave Hlaleah Florida 33012 Phone 305 557-2024 SS NEW * NEW * NEW BUY ECONO-PAC & SAVE WACO HKS-1GREAT LAKES TRAINER GREAT LAKES SPECIAL2T1A/2T1E PLAN$27OOppPLAN$27ttpp PG Cowl$27OOpp FG Cowl527OOpp F G Pants$25ttpp ECONO PAC$49OOpp ECOND-PACS70OOpp SAVE$600 SAVE $900 Parisian Moustique pian$17OOpp -. mixture reed valve todays ubiqui tous Cox 1/2As meetings interested modelers Brown delights producing engine pocket flash dis assembling spreading its parts out table before amazed onlookers Without too much prodding hell also demonstrate still operates just well day built Among pictures two fine examples 60 cu Brown Junior prototypes handbuilt Brown late 1931 early 1932 Both engine number A2 A5 share same basic characteristics though differ pther minor detail example like common production Browns later years engine A2 discharges its spent gases directly through tour D-shaped exhaust ports cut rear cylinder just above intake manifold engine A5 however exhaust ports concealed exhaust manifold two round threaded out lets Brown made least other engine manitolded like additional touch spark plug offset horizontally rear Incidentally both engines A2 A5 have steel pistons fitted curious ar rangement two cast iron piston rings dif ferent widthsan upper narrow com pression ring above lower very wide oil ring Note very short flared intake tubes sandcast crankcases handmade spark plugs common both early engines Max Bassetts Brown Junior number A17 manufactured Walter Hurleman Brown developed engines first pro duction tooling early summer 1932 different edge contour en gines bypass cover intake manifold indi cates parts die-stamped rather hand-formed engines A2 A5 intake tube also longer slightly larger diameter engine other 40 50 A-model Brown Juniors Hurleman said have produced before Bill Brown parted company late 1933 first have ringless precision-ground steel pistons remained hallmark qual ity model engines years afterward minor changes Hurleman continued manufacture limited quantities engine under own name until 1937 1938 Meanwhile Junior Motors Corporation organized early 1934 Bill Brown began oversee production yet another Brown Juniorthe 1934 model Bwhile still sophomore Penn State Financed Edward Roberts Philadelphia bankers son actually ran company Junior Motors turned out 50000 Brown engines before ceasing production eight years later Roberts served AMAs third president 1939 through 1942 hobbys earliest promoters Radio Control RS550S6530 good inexpensive hard-toget motor Top Flite 7 x 6 nylon Table 3 shows what happens input current input power rpm voltage varied test voltage range chosen might easily represent battery behavior just-off-charge through its useful Electrics/Kopski Continued page 95 run-down Notice dramatic power change Again static behavior shown table indication flight behavior Yes Electric noticeably hotter right after charge Ni-Cds characteristically drop initial high terminal voltage rapidly slowly decline through long plateau finally drop dramatically end-ofcharge Thats plane flies too Ive always feeling some suppliers ad vertise products performance right charge peak 3 For given propeller small change rpm representative significant change power/performance other key piece information evident Table 3 Dont treat few hundred rpm change disregard works Gas too seemingly small change tach ometer reading can indeed significant tachometer accuracy youre comparing results others Now well look implications changing prop size both diameter pitch 4 Variation prop size has signifi cant effect power performance demonstrate used favorite motors older version Astro 075 motor powered constant 70 volts propellers used Top Flite wood Labeled size assumed accurate First diameter held constant pitch varied results shown Table 4 pitch held constant 170 Model Aviation 4-STROKE ENGINE SALE COMPARE & SAVE OSFS4O8950 OSFS6O12500 OS ES 7514500 OS ES 1 20T34900 ENYA4O-4C 50 ENYA6O-4C- -14950 ENYA9O-4C 950 SAITO 308450 SAITO 40-Il9950 SAITO4510950 SAITO 90T29950 TERMS Prepald check money order Include $250 UPS avid street address Calif residents add 6% sales tax No credit cards please Allow 2 weeks delivery REDWOOD hobby Imports PO BOX 6171 SANTA ROSA CALIF 95401 Sublect stock hand Designers Builders Fine PRE-BUILT RIC Models Fire Fox Pre-Built Price $12495 Engine Size 40 cu Wing Span 521A Radio 4 Channels balsa construction Ready fine sand covpr Control surfaces hinged Has bolt-on wing HalIco landing gear ABS wheel pants mounted axels stalled Fitted canopy Instruction booklet hardware included ERO 3850 US Hwy 19 No Palm Harbor FL 33463 ECH RIC813 938-3266 Dealer Inquiries Invited Oroer Today Send check MO also accept Master Card Visa Models shipped 350 PSI carton via UPS Add $850 shipping han dling Florida residents add 5% sales tax diameter varied results shown Table 5 Tables 4 5 can easily see variations prop size can significantly affect motor power examples applied voltage held constant current increased prop size thus power increased illustrates rather graphic fashion relationship power input up point power out put increasing prop size power increase has associated dual con sequences rapid battery discharge high enough currents some risk motor brushes 5 For constant applied voltage slower motor turns higher current drain also evident Tables 4 5 Thus fast-moving plane effective propeller rpm creases due prop unloading cur rent demand drops Translation longer run ning time Conversely small prop turning high revs large slow-moving glidertype approaching static test conditions relatively higher current inefficient power utilization because prop slip ping example larger slowerturning prop speed reducer will make much better use available energy stored battery case current demand always drops flight its question much later test conditions used demon strations herein considered within reasonable range operating capability motors used except * values cases data taken very quickly higher current levels either known damaging sure did want find out other hand some data points power levels too low useful flight Nevertheless representations believed fair Again its relative performance parame ters absolute accuracy mat ters 6 The power input required motors turn given prop same rpm nearly same may surprising performance factor vividly shown accompanying graph compares power input 11 samples nine different motor types turning same 6 x 4 propeller same propeller eight 11 motors performed within ranges shown Table 6 Three motors considered removed enough trend excluded table removed inefficient power input watts 51 10000 rpm 70 11000 101 12000 information evident part propeller determines input power given rpm part motors used comparable efficiencyat least over reasonable op erating power range de signed last statement means power lost motor process doing its intended job about same motors lost power mostly form heatmore later Its interesting note the least efficient motors tested among costly middle-of-the-road occupied comparatively low-cost sleevebearing types some exceptions course efficient motors consume least power spinning given prop will run longest par ticular battery Names motors tests will supplied unless inquiier manufacturers involved 40 wing 15 25 Engines Dealers & Distributors Welcomed Phone 703 273-9593 FLYLINE MODELS INC PO Box 2136 Fairfax Virginia 22031 USA November 1983 171 magic Dragon Trainer Pre-Bui Price $9995 Engine Size 25 CU Wing Span 55 Radio 3 4 Channels balsa construction Ready fine sand cover Control surfaces hinged HalIco landing gear 5132 nose gear strut Fitted canopy Instruction booklet hardware included Five Other Models Available Send Now Free Brochure ctru~ Pre-BuIlt lrice $10995 Engine Size 40 Wing Span 52 Wing Area 614 sq Length 385/8 Weight 4 lbs Radio 4 Channels IN STOCK FOR IMMEDIATE SHIPMENT New 30 CID QUADRA $20950 New 22 CiD QUADRA $10950 Reg 22 QUADRA $10400 Brisighelia Fiywheei $12400 Rag 22 QUADRA POWER ASSEMBLY ONLY$0400 QUADRA REPAIR 000 pius parts Jim Messer ERCOUPEPLANS $2395 KIT $23995 Jim Messer TOMAHAWKPLANS $2395 KIT $25gg5 Jim Messer9BALLTRAINER PLANS 41895 KIT gggg BALSA BASSWOOD 1811 ajuesl 35% OFF Concept FLEET PLANS $2995 KIT 515995 COWL $1995 FLOATS 35115 scale core $1795 complete kit $3996 FLOATS 4W scalecores $2195 complete kit $4795 CECONiTE Product 10) OFF Sig J3 CUB KIT $12495 PLANS SUPER STEARMAN Godfrey $2895 STARDUSTER TOO h Brisighelia J-2 CUB Neiitz $2995 VOLKSPLANE Chicken Charlie $2395 COCKPIT KITS Tomahawk F4U1 Spitfire $2398 Ercoupe $2095 Stearman $2295 Citabria $2495 J3 Cub $2195 ME-lOg $2295 Fleet $2195 US Quadra FUEL TANKS16 ou $695 32 oz 5795 FIBERGLASS ARROW SHAFTS 5/10 s 32 long 0/$1000 24-Hour Service . Add $250 postage Send Bank Check Money Order JIM MESSERS QUALITY MODEL PRODUCTS 106 Valley View Dr Aliegany NY 14706 R/C Capitol offers worlds finest RC custom built-up RC scale aircraft Quarter Scala PlansEa 92495PP Quarter Scale Pertial KitsEn $95OOPP Quarter Scale Custom-Built DeluxEa $500OOPP Piper Pacer PA-20 89 Wingspan Piper Tn-Pacer PA-22 89 Wingspan DH-85 Leopard Moth 111 Wingspan DH80A Puss Moth 111 Wingspan Please send $100 self-addressed stamped envelope complete list HOBBY CAPITOL RIC ESt 1951 46 N Oak St Ventura CA 93001 805643-7616 e 642-8465 Distributors Finest Quality Built-Up A/C Aircraft Custome Built Ready-ToFly Radio Controlled Modal Airplanes Classic R/C Scale SGRAT LAK TII LT-50 Electric Motor 01 Cu Ifl equivelent gas engine displacement Send self-addressed stamped envelope catalog ap plication notes Leisure 11 Deerspringllrvine/CA 92714 readers think Im hung up small motors props allow pro vide some information bigger stuff Table 7 data limited admittedliy represents some unlikely unde sirable combinations point about props determining motor input power fur ther illustrated comparison Table 7 really stands out deserves further comment Im refer ring Astro 25 Astro 075 speed reducer both turning 9 00 rpm Remarkable isnt Whats catch None some considerations 25 operating well below its nor mal intended power level twice power level shown might say 25 being underutilized example other hand 075 system being very well used Its lighter weight lower cost could reasonably pushed mOch higher normal power capability 25 Whatever prop dictating power demand point Im making get Part 4 batteries youll see energy tanks must con sidered part big picturethe total Electric system picturewhere choice system component sort team choice Translation want run 9 x 6 8000 other motor/prop/rpm combination fly some plane some specific duration battery because practicalities cell size number cells charging considerations 2 Motor propeller plane efficiency data examples given part have nominal operating condi tions motor propeller mean operating conditions would representative good fly ing power levels Putting yet another way would conditions reasonably good efficiency motors props presented used suitable plane Efficiency power output divided power input always number less meaning get less out put difference wasted power mentioned earlier Another point made earlier electrical power put motor easily measured simply product motor input volt age wattage current Power outputrelated work done motor its propeller moving both air planeis easily measured Anyway efficiency curve has shape bit like hook clothes hanger maybe like climb level-off dive roller coaster means some power range maximizing efficiencythe place percentage power lost least information Ive seen peak actually rounded usually represents rather broad range good power utilization 172 Model Aviation motor/prop maY primary con sideration Power Soar New Heights other words dont have oper ating exactly very peak impossible maintain anyway enjoy lot great flying Far either side broad max imum region however operating ex tremes efficiency can terrible flight will also terrible what extremes low ends efficiency curve can come end low power levels ratio output power input power small because example much input power goes kinds losses shown Table Ithe no prop power used overcome friction etc Thus small amount power de livered prop may comparable less lost would almost al ways no-flight condition anyway saw power region very low wattage region indeed other end efficiency curve very high input power levels motor losses rise very rapidly due example heating area operation cur rent input very high such too much voltage applied too large prop used power lost heat rises rapidly because power product current times current times resistance commonly called squared R' losses resistance armature windings brush-tocommutator contact resistance brush material brush connection resistance big driver current times itself Thus under such conditions more current input lower lower percentage power output ef ficiency curve drops off sooner later motor may go belly up excess ive brush heat heating concern Ive alluded often comes few words motors currently use simply adaptations some readily available often imported standard low cost unit intended con sumer applications nothing wrong this allows variety low cost what can see appli cation model use probably tasks motors far other intended ap plication application feel putting motors past limits design intent experience first mani festation brush damage very high currents Anyway more motors becoming available have much better behavior regard other things parts continuing Elec tric evolution Later get planes stallations well look some actual exam ples operation some guidelines help assure longevity investment along lots enjoyable flying fun now should clear motor prop independent plane What can too much motor bench static may case air providing plane moves out quickly allowing prop unload As mentioned earlier motor turning small November 1983 173 prop fast slowly-moving glider-type inefficient potentially bad-for-themotor situation Now let describe ex ample thats similar other direc tion Ive twice occasion help someone ARF Kraft Shoestring tractive planes 05-sized motor six cells 06 Ah size nylon props 8 x 6 planes just sorta mushed along studying situation respect weight area etc seemed really should fly better changed prop nylon 7 x 6 did trick motor turned up faster expected drew less current motor-prop-plane combination now much better fact plane much fun fly Simple huh does know what may have realized clue solution came three paragraphs earlierlook back see Admittedly above discussions simplifications incomplete theres involved motor/prop/plane performance discussed far think weve gone far enough get general ideathat theres variety motors avail able work quite well prop choice power closely related good results efficient motor/plane/prop combination thats needed Well al subject must covered before can look what works well together WS 54 29 35 ENGINtS 3 CHANNEL THE BEGINNERS KITTEN AND EXPERTS TIGER Revolutionary snap-on wing eliminates bolts rnbber bands complete kit $54 95 dealer direct GEMINI MODELS INC PO Bn 1168 Pasc NJ 07055 topic comes up next month Batteries Remember promised two things basics things work intend keep commitment So far weve dealing mostly first part promise will seriously pursue Elec trics basics given will sooner later directly contribute success own Electric design choices part making guy mentioned Part 2 guy understands basics knows what to worksthe guy whos 'got together Electrics closing note first four parts series will have written before Part 1 reaches readers expect installment will raise questions Despite good inten tions know some things will overlooked some things will unclear can welcome critic regard Perhaps most-asked questions can collected answers presented read wrap-up installment meantime will endeavor responsive individuals expediently possible Please direct questions SASE author Bob Kopski 25 West End Dr Lansdale PA 19446 SAFE FLYING IS NO ACCIDENT SAM Champs/Mathews Continued page 81 really means something SAM types host chapter SAM No Contest Director Jim Thomas obviously done homework example fact no sooner mentioned nice would someone water down dusty access road water truck arrived did just process repeated two three times daily Although no hookups available campers motor homes contest site sev eral self-contained vehicles well tenters campers stayed ovemight site Motel ar rangements well-handled Tanya Baird Chamber Commerce office available room LaJunta reserved mid-April attendees found accommodations nearby towns Rates very reasonable Ad ditional rooms available Otero Junior Col lege stayed reported clean air-conditioned facilities lots bull ses sions progress times lounge area concessionaire provided food drink flying fieldagain very reasonable prices However breakfast Laiunta proved bit hassle sudden influx hungry modelers demanding breakfast 600 am overtaxed staffs local restaurants making rather slow service fact some eateries didnt open until 700 am seems real crux problem contest manage ments decision start flying 800 rather originally-announced time 900 am scheduling change made order get competition over hour earlierto get out heat As matter fact since LaJunta far eastern edge Mountain timezone flying could have scheduled start 600 am contest day could have ended early 300 pm Go Upty Up-Up Problems effect high altitude engine power glide models didnt seem severe anticipated Although power-loss certainly factor major problems seemed i/A reed-valve engines Texaco event Climbouts certainly lower slower peculiar distribution lift atmosphere real oddity saw As repeatedly observed lift existed strata model would riding rather large boomer another plane immediately below above would downer Ther mal pattems much like seen Lake Charles LA accustomed finding Great Plains 174 Model Aviation product can recommendSUPER HAND SAN DER Dealers & Distributors Wanted confidenceHOBBIESTSee Hobby Dealer Call Art Gross Enterprises HOBBY DEALERCa// Distributor 06/743-9332 ART GROSS ENTERPRISES 12516 MAPLEWOOD AVE EDMONDS WA 98020 DUAL PERSONAUTY TRAINER GEENIS BEAUTIFULI SUPER CHAMP [F6T\F1 Invited Liti IjI.u Inc Dealer inquiries High pert onnante model engine connecting rods connecting rods made tha beat materials available designed give long service eliminate rod breakage modern high-Peef mance model engines Used leading aircraft boat car racers hobbyists Rods available popular model engines Look RPM new innovative products wish proven performance records Richardson Precision Machining Inc 5070 Golden Dr San Jose cA 5612914061 2S7-7068
Edition: Model Aviation - 1983/11
Page Numbers: 93, 94, 95, 170, 171, 172, 173, 174
This authors testing setup evaluation motors props results shown tables discussed text power supply fully adjustable zero 30 volts up 20 amperes two digital readouts motor voltage current analog meter tachometer optical pickup remotely located under motor mount Light source also remotely located Photos author THE FIRST INSTALLMENT series September issue described some pros cons electric-powered models last month covered motors use Some basic aspects motors de scribed practical considerations covered Earlier asked have faith read daringly onward remind because realize subject part may appear both simple some strange others However think some up coming information will surprising interesting manyand perhaps little confusing ditficult others first reading still others some what fol lows may downright boring seem totally irrelevant taken alone section however combined ether parts series will provide very intimate overall feel exactly what \Ki O iOE ra popellor rave electricpowered models yoi re new Electrics authors test results may astound second reading may required fully grasp some points thai made that1s what takes suggest Part 3 November 1983 93 goes motor battery pro peller given planeand affect flight results get other words series continues will come together' encourage un daunted continuance series Im sure will find worthwhile presentation seems too slow 80 70 60 -50 40 -8 tedious remern ber introduction Electricson installment plan Its necessarily easy installment plan either read write Hox ever maintain subject can generally simple oc t V 0 0 0 ----V e Lu 0 0 0 0 0 -I C V e 0 V C 0 0 RPM X 1000 91011 SC V0 certainly successful though neces sadly short Perhaps some readers have disap pointments Electrics just because some details made light glossed over elsewhere Thats Model Avi ation has planned seriesto make sure adequate introductory treatment such anyone wants can very successful Electric flier theres some useful stuff Gas guys honest well-intended series cannot complete detail-perfect several reasons dont know everything Another Im trying se lect meaningful useful offer ings consistent limitations pub lication space presentation time can fact best can can criticautomaticallyby asking questions 1 Propellers power Now Chave seen some Electric models Part have some introductory insight motors Part 2 could wondering what business concerning power heating performance about Lets look what happens motor required its thingturn prop power plane leading suppliers Electric flight systems provide instructions regarding choice model size weight suit able propellers things will also addressed another part series meantime get good feel motor operation propellers power lets look things static environment ie bench rather flight experience excellent correlation tween what observe bench what experience air A Power inputno prop Electrical power product electric potential volts electric current amps case motor input power motor terminal voltage times motor terminal input current amperage product V x power watts power comes frm energy 12131415 tank battery tank specific size can deliver its fill Part 4 will cover batteries detail discuss much tanks' can deliver Now however going get feel just Shown motor input power various motor speeds rpm 11 samples nine different motor types swinging Cox 6-4 gray prop Note different symbol 11 motors Connect like symbols form smooth performance curves through various speeds Note generally tight clusters data points throughout range test 94 Model Aviation Table 1 Typical Motor Power InputNo Prop MotorVoltsAmpsWatts Astro 0560075450 p/n 210770078546 80081648 90084756 Leisure LT-5050119595 Pattern Wind60124744 7013091 Mabuchi5011859 RS540S65276013078 70146102 80153122 Table 2 Performance Variation Various Same Size Props Propeller 64AmpsWatts Top Flite Nylon1168113300 Top Flite Wood13393112700 Cox Gray155*10912200 Table 3 Typical Motor/Propeller Performance Voltage Variation VoltsAmpsWattsRPM 60795488000 65905598550 70100709050 75110839600 801219710000 8513011110500 133 120 110 100 90 much fuel used motors next month youll have appreciation Part 4 As mentioned earlier motor running no prop draws small amount current sufficient overcome losses due friction other things illustrate sev eral examples shown Table measurements made using test setup pictured Notice something particular about data Table example motor current increase large crease voltage caused will case prop measurements tests made using convenient adjustable power supply exactly same re sults would occur motor bat tery interested power supply pictured capable up 30 volts 20 amps has remote voltage sense assure correct voltage motor terminals Also has adjustable current limit dont have accident during some zealous data run power capa bility may sound impressive believe expect need capability near future point want make special note has experience Ive told same Electric flight system suppliers performance production flight motors varies about plus-or-minus 10% As youll also see props also vary greatly load present motor battery course measurement motor performance has instrumentation accuracy associated Thus rea sons apparent differences Electric flight experience can occur Em noting now just case anyone reading has has read about different results B Power inputwith props ifl tables various motor performance mea surements different props ahown Whats mportant absoLve ac curacy relative performances -i particuiar notice bow rapidly input power changes tbattery voltage dra matic eFfect piop size can hae youll see important use right prop temptation just stick bigger prop add another cell may have carefully con sidered What seems like small change may fact either present unbearable load motor lest cause decline power system efficiency Remember static demonstrations motor/prop moving forward actual flying condi tions aircraft speed etc can have signifi cant influence data 1 All propellers same size necessarily created equal demonstrate ran Leisure LT-50 Pattern Wind very nicely-made motor three different 6 X 4 props applied voltage held constant 70 volts much like battery would hold nearly-constant voltage Table 2 lists resulting current drain input power rpm Notice wide variation power input roughly translates about same variation power output flight per formance might inclined say prop better prop remember dont get something nothing output performance input power means faster battery dis charge shorter flight timealthough increased flight performance may very well worth depending plane want fly some simi larity running engine full bore vs half throttle latter goes longer tank fuel Does Cox 6 x 4 gray fly aerobatic Jack Rabbit hotter Top Flight 6 x 4 nylon betcha buddy gives shorter flight too 2 A small change voltage makes big change performance demon strate propped Mabuchi Continued page 170 November 1983 95 Table 4 Effect Propeller Pitch Motor Input Power PropAmpsWattsRPM 8-468487950 8-580567550 8-696677000 8-8117826200 Table 5 Effect Prop Diameter Motor Input Power PropAmpsWattsRPM 6-437269000 7-450358400 8-469487900 Table 7 Some Larger Motor/Prop/Power Demonstrations MotorPropRPMPower Astro 259-6 wood700086 watts Astro 109-6 wood700090 watts Astro 075* *9-6 wood700080 watts Astro 259-6 wood8000126 watts Astro 075* *9-6 wood8000115 watts Astro 2512-6 wood5100115 watts Astrol5**12-6wood510096watts Now 1 ** means motors used matching speed reducers 2 In cases motor clearly over-propped operating conditions carefully controlled no risk motor involved 3 No voltages currents givenonly product power voltages currents generally well removed values would considered normal motor its normal prop Consider above academic exercises necessarily practical cases Table 6 Input Power Given 6-3 Prop Specific RPM RPM100001100012000 Watts44/360/S77 16 Close-up motor being tested Power motor supplied through cables connector extreme left Two test clip connections provide remote sensing precise control applied voltage Wood V-block underneath motor has rubber padding conjunction rubberbands stretched across top provide sturdy mount hold largest motors intended models NOW THERES QUICK AND EASY WAY OF ClEANING YOUR MODEL CRAFTS Super-K Model Cleaner Remaves fu Residue dirt contact1 CEJTS ClEANING TiME IN HALF Just spray model solvent wtpe soft cloth paper towel SIMPLE AS THAT Leaves craft showcase cleani eWoni hami Pahits Coverings Dries clew fast Eminates Ihe WOk cleaning model Strong Professonal Quality formula Great Model Craft Scots manes Helicopters Cleans Gently Protects delicate model DEALERS WANTED DOMESTIC & OVERSEAS WE EXPORT Hurry Have product shelves time Christmas guaranteed top seller Sugg retail $550 per gallon Contact us price structures ordering Information Also ask about other Super-K products Model Industry Ale Manufacturers & Major Brands DIstributors Model Engines Kits Radios & Accessories Super-K brand Kings RadIo Control Hobbles International 3960 West 16th Ave Hlaleah Florida 33012 Phone 305 557-2024 SS NEW * NEW * NEW BUY ECONO-PAC & SAVE WACO HKS-1GREAT LAKES TRAINER GREAT LAKES SPECIAL2T1A/2T1E PLAN$27OOppPLAN$27ttpp PG Cowl$27OOpp FG Cowl527OOpp F G Pants$25ttpp ECONO PAC$49OOpp ECOND-PACS70OOpp SAVE$600 SAVE $900 Parisian Moustique pian$17OOpp -. mixture reed valve todays ubiqui tous Cox 1/2As meetings interested modelers Brown delights producing engine pocket flash dis assembling spreading its parts out table before amazed onlookers Without too much prodding hell also demonstrate still operates just well day built Among pictures two fine examples 60 cu Brown Junior prototypes handbuilt Brown late 1931 early 1932 Both engine number A2 A5 share same basic characteristics though differ pther minor detail example like common production Browns later years engine A2 discharges its spent gases directly through tour D-shaped exhaust ports cut rear cylinder just above intake manifold engine A5 however exhaust ports concealed exhaust manifold two round threaded out lets Brown made least other engine manitolded like additional touch spark plug offset horizontally rear Incidentally both engines A2 A5 have steel pistons fitted curious ar rangement two cast iron piston rings dif ferent widthsan upper narrow com pression ring above lower very wide oil ring Note very short flared intake tubes sandcast crankcases handmade spark plugs common both early engines Max Bassetts Brown Junior number A17 manufactured Walter Hurleman Brown developed engines first pro duction tooling early summer 1932 different edge contour en gines bypass cover intake manifold indi cates parts die-stamped rather hand-formed engines A2 A5 intake tube also longer slightly larger diameter engine other 40 50 A-model Brown Juniors Hurleman said have produced before Bill Brown parted company late 1933 first have ringless precision-ground steel pistons remained hallmark qual ity model engines years afterward minor changes Hurleman continued manufacture limited quantities engine under own name until 1937 1938 Meanwhile Junior Motors Corporation organized early 1934 Bill Brown began oversee production yet another Brown Juniorthe 1934 model Bwhile still sophomore Penn State Financed Edward Roberts Philadelphia bankers son actually ran company Junior Motors turned out 50000 Brown engines before ceasing production eight years later Roberts served AMAs third president 1939 through 1942 hobbys earliest promoters Radio Control RS550S6530 good inexpensive hard-toget motor Top Flite 7 x 6 nylon Table 3 shows what happens input current input power rpm voltage varied test voltage range chosen might easily represent battery behavior just-off-charge through its useful Electrics/Kopski Continued page 95 run-down Notice dramatic power change Again static behavior shown table indication flight behavior Yes Electric noticeably hotter right after charge Ni-Cds characteristically drop initial high terminal voltage rapidly slowly decline through long plateau finally drop dramatically end-ofcharge Thats plane flies too Ive always feeling some suppliers ad vertise products performance right charge peak 3 For given propeller small change rpm representative significant change power/performance other key piece information evident Table 3 Dont treat few hundred rpm change disregard works Gas too seemingly small change tach ometer reading can indeed significant tachometer accuracy youre comparing results others Now well look implications changing prop size both diameter pitch 4 Variation prop size has signifi cant effect power performance demonstrate used favorite motors older version Astro 075 motor powered constant 70 volts propellers used Top Flite wood Labeled size assumed accurate First diameter held constant pitch varied results shown Table 4 pitch held constant 170 Model Aviation 4-STROKE ENGINE SALE COMPARE & SAVE OSFS4O8950 OSFS6O12500 OS ES 7514500 OS ES 1 20T34900 ENYA4O-4C 50 ENYA6O-4C- -14950 ENYA9O-4C 950 SAITO 308450 SAITO 40-Il9950 SAITO4510950 SAITO 90T29950 TERMS Prepald check money order Include $250 UPS avid street address Calif residents add 6% sales tax No credit cards please Allow 2 weeks delivery REDWOOD hobby Imports PO BOX 6171 SANTA ROSA CALIF 95401 Sublect stock hand Designers Builders Fine PRE-BUILT RIC Models Fire Fox Pre-Built Price $12495 Engine Size 40 cu Wing Span 521A Radio 4 Channels balsa construction Ready fine sand covpr Control surfaces hinged Has bolt-on wing HalIco landing gear ABS wheel pants mounted axels stalled Fitted canopy Instruction booklet hardware included ERO 3850 US Hwy 19 No Palm Harbor FL 33463 ECH RIC813 938-3266 Dealer Inquiries Invited Oroer Today Send check MO also accept Master Card Visa Models shipped 350 PSI carton via UPS Add $850 shipping han dling Florida residents add 5% sales tax diameter varied results shown Table 5 Tables 4 5 can easily see variations prop size can significantly affect motor power examples applied voltage held constant current increased prop size thus power increased illustrates rather graphic fashion relationship power input up point power out put increasing prop size power increase has associated dual con sequences rapid battery discharge high enough currents some risk motor brushes 5 For constant applied voltage slower motor turns higher current drain also evident Tables 4 5 Thus fast-moving plane effective propeller rpm creases due prop unloading cur rent demand drops Translation longer run ning time Conversely small prop turning high revs large slow-moving glidertype approaching static test conditions relatively higher current inefficient power utilization because prop slip ping example larger slowerturning prop speed reducer will make much better use available energy stored battery case current demand always drops flight its question much later test conditions used demon strations herein considered within reasonable range operating capability motors used except * values cases data taken very quickly higher current levels either known damaging sure did want find out other hand some data points power levels too low useful flight Nevertheless representations believed fair Again its relative performance parame ters absolute accuracy mat ters 6 The power input required motors turn given prop same rpm nearly same may surprising performance factor vividly shown accompanying graph compares power input 11 samples nine different motor types turning same 6 x 4 propeller same propeller eight 11 motors performed within ranges shown Table 6 Three motors considered removed enough trend excluded table removed inefficient power input watts 51 10000 rpm 70 11000 101 12000 information evident part propeller determines input power given rpm part motors used comparable efficiencyat least over reasonable op erating power range de signed last statement means power lost motor process doing its intended job about same motors lost power mostly form heatmore later Its interesting note the least efficient motors tested among costly middle-of-the-road occupied comparatively low-cost sleevebearing types some exceptions course efficient motors consume least power spinning given prop will run longest par ticular battery Names motors tests will supplied unless inquiier manufacturers involved 40 wing 15 25 Engines Dealers & Distributors Welcomed Phone 703 273-9593 FLYLINE MODELS INC PO Box 2136 Fairfax Virginia 22031 USA November 1983 171 magic Dragon Trainer Pre-Bui Price $9995 Engine Size 25 CU Wing Span 55 Radio 3 4 Channels balsa construction Ready fine sand cover Control surfaces hinged HalIco landing gear 5132 nose gear strut Fitted canopy Instruction booklet hardware included Five Other Models Available Send Now Free Brochure ctru~ Pre-BuIlt lrice $10995 Engine Size 40 Wing Span 52 Wing Area 614 sq Length 385/8 Weight 4 lbs Radio 4 Channels IN STOCK FOR IMMEDIATE SHIPMENT New 30 CID QUADRA $20950 New 22 CiD QUADRA $10950 Reg 22 QUADRA $10400 Brisighelia Fiywheei $12400 Rag 22 QUADRA POWER ASSEMBLY ONLY$0400 QUADRA REPAIR 000 pius parts Jim Messer ERCOUPEPLANS $2395 KIT $23995 Jim Messer TOMAHAWKPLANS $2395 KIT $25gg5 Jim Messer9BALLTRAINER PLANS 41895 KIT gggg BALSA BASSWOOD 1811 ajuesl 35% OFF Concept FLEET PLANS $2995 KIT 515995 COWL $1995 FLOATS 35115 scale core $1795 complete kit $3996 FLOATS 4W scalecores $2195 complete kit $4795 CECONiTE Product 10) OFF Sig J3 CUB KIT $12495 PLANS SUPER STEARMAN Godfrey $2895 STARDUSTER TOO h Brisighelia J-2 CUB Neiitz $2995 VOLKSPLANE Chicken Charlie $2395 COCKPIT KITS Tomahawk F4U1 Spitfire $2398 Ercoupe $2095 Stearman $2295 Citabria $2495 J3 Cub $2195 ME-lOg $2295 Fleet $2195 US Quadra FUEL TANKS16 ou $695 32 oz 5795 FIBERGLASS ARROW SHAFTS 5/10 s 32 long 0/$1000 24-Hour Service . Add $250 postage Send Bank Check Money Order JIM MESSERS QUALITY MODEL PRODUCTS 106 Valley View Dr Aliegany NY 14706 R/C Capitol offers worlds finest RC custom built-up RC scale aircraft Quarter Scala PlansEa 92495PP Quarter Scale Pertial KitsEn $95OOPP Quarter Scale Custom-Built DeluxEa $500OOPP Piper Pacer PA-20 89 Wingspan Piper Tn-Pacer PA-22 89 Wingspan DH-85 Leopard Moth 111 Wingspan DH80A Puss Moth 111 Wingspan Please send $100 self-addressed stamped envelope complete list HOBBY CAPITOL RIC ESt 1951 46 N Oak St Ventura CA 93001 805643-7616 e 642-8465 Distributors Finest Quality Built-Up A/C Aircraft Custome Built Ready-ToFly Radio Controlled Modal Airplanes Classic R/C Scale SGRAT LAK TII LT-50 Electric Motor 01 Cu Ifl equivelent gas engine displacement Send self-addressed stamped envelope catalog ap plication notes Leisure 11 Deerspringllrvine/CA 92714 readers think Im hung up small motors props allow pro vide some information bigger stuff Table 7 data limited admittedliy represents some unlikely unde sirable combinations point about props determining motor input power fur ther illustrated comparison Table 7 really stands out deserves further comment Im refer ring Astro 25 Astro 075 speed reducer both turning 9 00 rpm Remarkable isnt Whats catch None some considerations 25 operating well below its nor mal intended power level twice power level shown might say 25 being underutilized example other hand 075 system being very well used Its lighter weight lower cost could reasonably pushed mOch higher normal power capability 25 Whatever prop dictating power demand point Im making get Part 4 batteries youll see energy tanks must con sidered part big picturethe total Electric system picturewhere choice system component sort team choice Translation want run 9 x 6 8000 other motor/prop/rpm combination fly some plane some specific duration battery because practicalities cell size number cells charging considerations 2 Motor propeller plane efficiency data examples given part have nominal operating condi tions motor propeller mean operating conditions would representative good fly ing power levels Putting yet another way would conditions reasonably good efficiency motors props presented used suitable plane Efficiency power output divided power input always number less meaning get less out put difference wasted power mentioned earlier Another point made earlier electrical power put motor easily measured simply product motor input volt age wattage current Power outputrelated work done motor its propeller moving both air planeis easily measured Anyway efficiency curve has shape bit like hook clothes hanger maybe like climb level-off dive roller coaster means some power range maximizing efficiencythe place percentage power lost least information Ive seen peak actually rounded usually represents rather broad range good power utilization 172 Model Aviation motor/prop maY primary con sideration Power Soar New Heights other words dont have oper ating exactly very peak impossible maintain anyway enjoy lot great flying Far either side broad max imum region however operating ex tremes efficiency can terrible flight will also terrible what extremes low ends efficiency curve can come end low power levels ratio output power input power small because example much input power goes kinds losses shown Table Ithe no prop power used overcome friction etc Thus small amount power de livered prop may comparable less lost would almost al ways no-flight condition anyway saw power region very low wattage region indeed other end efficiency curve very high input power levels motor losses rise very rapidly due example heating area operation cur rent input very high such too much voltage applied too large prop used power lost heat rises rapidly because power product current times current times resistance commonly called squared R' losses resistance armature windings brush-tocommutator contact resistance brush material brush connection resistance big driver current times itself Thus under such conditions more current input lower lower percentage power output ef ficiency curve drops off sooner later motor may go belly up excess ive brush heat heating concern Ive alluded often comes few words motors currently use simply adaptations some readily available often imported standard low cost unit intended con sumer applications nothing wrong this allows variety low cost what can see appli cation model use probably tasks motors far other intended ap plication application feel putting motors past limits design intent experience first mani festation brush damage very high currents Anyway more motors becoming available have much better behavior regard other things parts continuing Elec tric evolution Later get planes stallations well look some actual exam ples operation some guidelines help assure longevity investment along lots enjoyable flying fun now should clear motor prop independent plane What can too much motor bench static may case air providing plane moves out quickly allowing prop unload As mentioned earlier motor turning small November 1983 173 prop fast slowly-moving glider-type inefficient potentially bad-for-themotor situation Now let describe ex ample thats similar other direc tion Ive twice occasion help someone ARF Kraft Shoestring tractive planes 05-sized motor six cells 06 Ah size nylon props 8 x 6 planes just sorta mushed along studying situation respect weight area etc seemed really should fly better changed prop nylon 7 x 6 did trick motor turned up faster expected drew less current motor-prop-plane combination now much better fact plane much fun fly Simple huh does know what may have realized clue solution came three paragraphs earlierlook back see Admittedly above discussions simplifications incomplete theres involved motor/prop/plane performance discussed far think weve gone far enough get general ideathat theres variety motors avail able work quite well prop choice power closely related good results efficient motor/plane/prop combination thats needed Well al subject must covered before can look what works well together WS 54 29 35 ENGINtS 3 CHANNEL THE BEGINNERS KITTEN AND EXPERTS TIGER Revolutionary snap-on wing eliminates bolts rnbber bands complete kit $54 95 dealer direct GEMINI MODELS INC PO Bn 1168 Pasc NJ 07055 topic comes up next month Batteries Remember promised two things basics things work intend keep commitment So far weve dealing mostly first part promise will seriously pursue Elec trics basics given will sooner later directly contribute success own Electric design choices part making guy mentioned Part 2 guy understands basics knows what to worksthe guy whos 'got together Electrics closing note first four parts series will have written before Part 1 reaches readers expect installment will raise questions Despite good inten tions know some things will overlooked some things will unclear can welcome critic regard Perhaps most-asked questions can collected answers presented read wrap-up installment meantime will endeavor responsive individuals expediently possible Please direct questions SASE author Bob Kopski 25 West End Dr Lansdale PA 19446 SAFE FLYING IS NO ACCIDENT SAM Champs/Mathews Continued page 81 really means something SAM types host chapter SAM No Contest Director Jim Thomas obviously done homework example fact no sooner mentioned nice would someone water down dusty access road water truck arrived did just process repeated two three times daily Although no hookups available campers motor homes contest site sev eral self-contained vehicles well tenters campers stayed ovemight site Motel ar rangements well-handled Tanya Baird Chamber Commerce office available room LaJunta reserved mid-April attendees found accommodations nearby towns Rates very reasonable Ad ditional rooms available Otero Junior Col lege stayed reported clean air-conditioned facilities lots bull ses sions progress times lounge area concessionaire provided food drink flying fieldagain very reasonable prices However breakfast Laiunta proved bit hassle sudden influx hungry modelers demanding breakfast 600 am overtaxed staffs local restaurants making rather slow service fact some eateries didnt open until 700 am seems real crux problem contest manage ments decision start flying 800 rather originally-announced time 900 am scheduling change made order get competition over hour earlierto get out heat As matter fact since LaJunta far eastern edge Mountain timezone flying could have scheduled start 600 am contest day could have ended early 300 pm Go Upty Up-Up Problems effect high altitude engine power glide models didnt seem severe anticipated Although power-loss certainly factor major problems seemed i/A reed-valve engines Texaco event Climbouts certainly lower slower peculiar distribution lift atmosphere real oddity saw As repeatedly observed lift existed strata model would riding rather large boomer another plane immediately below above would downer Ther mal pattems much like seen Lake Charles LA accustomed finding Great Plains 174 Model Aviation product can recommendSUPER HAND SAN DER Dealers & Distributors Wanted confidenceHOBBIESTSee Hobby Dealer Call Art Gross Enterprises HOBBY DEALERCa// Distributor 06/743-9332 ART GROSS ENTERPRISES 12516 MAPLEWOOD AVE EDMONDS WA 98020 DUAL PERSONAUTY TRAINER GEENIS BEAUTIFULI SUPER CHAMP [F6T\F1 Invited Liti IjI.u Inc Dealer inquiries High pert onnante model engine connecting rods connecting rods made tha beat materials available designed give long service eliminate rod breakage modern high-Peef mance model engines Used leading aircraft boat car racers hobbyists Rods available popular model engines Look RPM new innovative products wish proven performance records Richardson Precision Machining Inc 5070 Golden Dr San Jose cA 5612914061 2S7-7068
Edition: Model Aviation - 1983/11
Page Numbers: 93, 94, 95, 170, 171, 172, 173, 174
This authors testing setup evaluation motors props results shown tables discussed text power supply fully adjustable zero 30 volts up 20 amperes two digital readouts motor voltage current analog meter tachometer optical pickup remotely located under motor mount Light source also remotely located Photos author THE FIRST INSTALLMENT series September issue described some pros cons electric-powered models last month covered motors use Some basic aspects motors de scribed practical considerations covered Earlier asked have faith read daringly onward remind because realize subject part may appear both simple some strange others However think some up coming information will surprising interesting manyand perhaps little confusing ditficult others first reading still others some what fol lows may downright boring seem totally irrelevant taken alone section however combined ether parts series will provide very intimate overall feel exactly what \Ki O iOE ra popellor rave electricpowered models yoi re new Electrics authors test results may astound second reading may required fully grasp some points thai made that1s what takes suggest Part 3 November 1983 93 goes motor battery pro peller given planeand affect flight results get other words series continues will come together' encourage un daunted continuance series Im sure will find worthwhile presentation seems too slow 80 70 60 -50 40 -8 tedious remern ber introduction Electricson installment plan Its necessarily easy installment plan either read write Hox ever maintain subject can generally simple oc t V 0 0 0 ----V e Lu 0 0 0 0 0 -I C V e 0 V C 0 0 RPM X 1000 91011 SC V0 certainly successful though neces sadly short Perhaps some readers have disap pointments Electrics just because some details made light glossed over elsewhere Thats Model Avi ation has planned seriesto make sure adequate introductory treatment such anyone wants can very successful Electric flier theres some useful stuff Gas guys honest well-intended series cannot complete detail-perfect several reasons dont know everything Another Im trying se lect meaningful useful offer ings consistent limitations pub lication space presentation time can fact best can can criticautomaticallyby asking questions 1 Propellers power Now Chave seen some Electric models Part have some introductory insight motors Part 2 could wondering what business concerning power heating performance about Lets look what happens motor required its thingturn prop power plane leading suppliers Electric flight systems provide instructions regarding choice model size weight suit able propellers things will also addressed another part series meantime get good feel motor operation propellers power lets look things static environment ie bench rather flight experience excellent correlation tween what observe bench what experience air A Power inputno prop Electrical power product electric potential volts electric current amps case motor input power motor terminal voltage times motor terminal input current amperage product V x power watts power comes frm energy 12131415 tank battery tank specific size can deliver its fill Part 4 will cover batteries detail discuss much tanks' can deliver Now however going get feel just Shown motor input power various motor speeds rpm 11 samples nine different motor types swinging Cox 6-4 gray prop Note different symbol 11 motors Connect like symbols form smooth performance curves through various speeds Note generally tight clusters data points throughout range test 94 Model Aviation Table 1 Typical Motor Power InputNo Prop MotorVoltsAmpsWatts Astro 0560075450 p/n 210770078546 80081648 90084756 Leisure LT-5050119595 Pattern Wind60124744 7013091 Mabuchi5011859 RS540S65276013078 70146102 80153122 Table 2 Performance Variation Various Same Size Props Propeller 64AmpsWatts Top Flite Nylon1168113300 Top Flite Wood13393112700 Cox Gray155*10912200 Table 3 Typical Motor/Propeller Performance Voltage Variation VoltsAmpsWattsRPM 60795488000 65905598550 70100709050 75110839600 801219710000 8513011110500 133 120 110 100 90 much fuel used motors next month youll have appreciation Part 4 As mentioned earlier motor running no prop draws small amount current sufficient overcome losses due friction other things illustrate sev eral examples shown Table measurements made using test setup pictured Notice something particular about data Table example motor current increase large crease voltage caused will case prop measurements tests made using convenient adjustable power supply exactly same re sults would occur motor bat tery interested power supply pictured capable up 30 volts 20 amps has remote voltage sense assure correct voltage motor terminals Also has adjustable current limit dont have accident during some zealous data run power capa bility may sound impressive believe expect need capability near future point want make special note has experience Ive told same Electric flight system suppliers performance production flight motors varies about plus-or-minus 10% As youll also see props also vary greatly load present motor battery course measurement motor performance has instrumentation accuracy associated Thus rea sons apparent differences Electric flight experience can occur Em noting now just case anyone reading has has read about different results B Power inputwith props ifl tables various motor performance mea surements different props ahown Whats mportant absoLve ac curacy relative performances -i particuiar notice bow rapidly input power changes tbattery voltage dra matic eFfect piop size can hae youll see important use right prop temptation just stick bigger prop add another cell may have carefully con sidered What seems like small change may fact either present unbearable load motor lest cause decline power system efficiency Remember static demonstrations motor/prop moving forward actual flying condi tions aircraft speed etc can have signifi cant influence data 1 All propellers same size necessarily created equal demonstrate ran Leisure LT-50 Pattern Wind very nicely-made motor three different 6 X 4 props applied voltage held constant 70 volts much like battery would hold nearly-constant voltage Table 2 lists resulting current drain input power rpm Notice wide variation power input roughly translates about same variation power output flight per formance might inclined say prop better prop remember dont get something nothing output performance input power means faster battery dis charge shorter flight timealthough increased flight performance may very well worth depending plane want fly some simi larity running engine full bore vs half throttle latter goes longer tank fuel Does Cox 6 x 4 gray fly aerobatic Jack Rabbit hotter Top Flight 6 x 4 nylon betcha buddy gives shorter flight too 2 A small change voltage makes big change performance demon strate propped Mabuchi Continued page 170 November 1983 95 Table 4 Effect Propeller Pitch Motor Input Power PropAmpsWattsRPM 8-468487950 8-580567550 8-696677000 8-8117826200 Table 5 Effect Prop Diameter Motor Input Power PropAmpsWattsRPM 6-437269000 7-450358400 8-469487900 Table 7 Some Larger Motor/Prop/Power Demonstrations MotorPropRPMPower Astro 259-6 wood700086 watts Astro 109-6 wood700090 watts Astro 075* *9-6 wood700080 watts Astro 259-6 wood8000126 watts Astro 075* *9-6 wood8000115 watts Astro 2512-6 wood5100115 watts Astrol5**12-6wood510096watts Now 1 ** means motors used matching speed reducers 2 In cases motor clearly over-propped operating conditions carefully controlled no risk motor involved 3 No voltages currents givenonly product power voltages currents generally well removed values would considered normal motor its normal prop Consider above academic exercises necessarily practical cases Table 6 Input Power Given 6-3 Prop Specific RPM RPM100001100012000 Watts44/360/S77 16 Close-up motor being tested Power motor supplied through cables connector extreme left Two test clip connections provide remote sensing precise control applied voltage Wood V-block underneath motor has rubber padding conjunction rubberbands stretched across top provide sturdy mount hold largest motors intended models NOW THERES QUICK AND EASY WAY OF ClEANING YOUR MODEL CRAFTS Super-K Model Cleaner Remaves fu Residue dirt contact1 CEJTS ClEANING TiME IN HALF Just spray model solvent wtpe soft cloth paper towel SIMPLE AS THAT Leaves craft showcase cleani eWoni hami Pahits Coverings Dries clew fast Eminates Ihe WOk cleaning model Strong Professonal Quality formula Great Model Craft Scots manes Helicopters Cleans Gently Protects delicate model DEALERS WANTED DOMESTIC & OVERSEAS WE EXPORT Hurry Have product shelves time Christmas guaranteed top seller Sugg retail $550 per gallon Contact us price structures ordering Information Also ask about other Super-K products Model Industry Ale Manufacturers & Major Brands DIstributors Model Engines Kits Radios & Accessories Super-K brand Kings RadIo Control Hobbles International 3960 West 16th Ave Hlaleah Florida 33012 Phone 305 557-2024 SS NEW * NEW * NEW BUY ECONO-PAC & SAVE WACO HKS-1GREAT LAKES TRAINER GREAT LAKES SPECIAL2T1A/2T1E PLAN$27OOppPLAN$27ttpp PG Cowl$27OOpp FG Cowl527OOpp F G Pants$25ttpp ECONO PAC$49OOpp ECOND-PACS70OOpp SAVE$600 SAVE $900 Parisian Moustique pian$17OOpp -. mixture reed valve todays ubiqui tous Cox 1/2As meetings interested modelers Brown delights producing engine pocket flash dis assembling spreading its parts out table before amazed onlookers Without too much prodding hell also demonstrate still operates just well day built Among pictures two fine examples 60 cu Brown Junior prototypes handbuilt Brown late 1931 early 1932 Both engine number A2 A5 share same basic characteristics though differ pther minor detail example like common production Browns later years engine A2 discharges its spent gases directly through tour D-shaped exhaust ports cut rear cylinder just above intake manifold engine A5 however exhaust ports concealed exhaust manifold two round threaded out lets Brown made least other engine manitolded like additional touch spark plug offset horizontally rear Incidentally both engines A2 A5 have steel pistons fitted curious ar rangement two cast iron piston rings dif ferent widthsan upper narrow com pression ring above lower very wide oil ring Note very short flared intake tubes sandcast crankcases handmade spark plugs common both early engines Max Bassetts Brown Junior number A17 manufactured Walter Hurleman Brown developed engines first pro duction tooling early summer 1932 different edge contour en gines bypass cover intake manifold indi cates parts die-stamped rather hand-formed engines A2 A5 intake tube also longer slightly larger diameter engine other 40 50 A-model Brown Juniors Hurleman said have produced before Bill Brown parted company late 1933 first have ringless precision-ground steel pistons remained hallmark qual ity model engines years afterward minor changes Hurleman continued manufacture limited quantities engine under own name until 1937 1938 Meanwhile Junior Motors Corporation organized early 1934 Bill Brown began oversee production yet another Brown Juniorthe 1934 model Bwhile still sophomore Penn State Financed Edward Roberts Philadelphia bankers son actually ran company Junior Motors turned out 50000 Brown engines before ceasing production eight years later Roberts served AMAs third president 1939 through 1942 hobbys earliest promoters Radio Control RS550S6530 good inexpensive hard-toget motor Top Flite 7 x 6 nylon Table 3 shows what happens input current input power rpm voltage varied test voltage range chosen might easily represent battery behavior just-off-charge through its useful Electrics/Kopski Continued page 95 run-down Notice dramatic power change Again static behavior shown table indication flight behavior Yes Electric noticeably hotter right after charge Ni-Cds characteristically drop initial high terminal voltage rapidly slowly decline through long plateau finally drop dramatically end-ofcharge Thats plane flies too Ive always feeling some suppliers ad vertise products performance right charge peak 3 For given propeller small change rpm representative significant change power/performance other key piece information evident Table 3 Dont treat few hundred rpm change disregard works Gas too seemingly small change tach ometer reading can indeed significant tachometer accuracy youre comparing results others Now well look implications changing prop size both diameter pitch 4 Variation prop size has signifi cant effect power performance demonstrate used favorite motors older version Astro 075 motor powered constant 70 volts propellers used Top Flite wood Labeled size assumed accurate First diameter held constant pitch varied results shown Table 4 pitch held constant 170 Model Aviation 4-STROKE ENGINE SALE COMPARE & SAVE OSFS4O8950 OSFS6O12500 OS ES 7514500 OS ES 1 20T34900 ENYA4O-4C 50 ENYA6O-4C- -14950 ENYA9O-4C 950 SAITO 308450 SAITO 40-Il9950 SAITO4510950 SAITO 90T29950 TERMS Prepald check money order Include $250 UPS avid street address Calif residents add 6% sales tax No credit cards please Allow 2 weeks delivery REDWOOD hobby Imports PO BOX 6171 SANTA ROSA CALIF 95401 Sublect stock hand Designers Builders Fine PRE-BUILT RIC Models Fire Fox Pre-Built Price $12495 Engine Size 40 cu Wing Span 521A Radio 4 Channels balsa construction Ready fine sand covpr Control surfaces hinged Has bolt-on wing HalIco landing gear ABS wheel pants mounted axels stalled Fitted canopy Instruction booklet hardware included ERO 3850 US Hwy 19 No Palm Harbor FL 33463 ECH RIC813 938-3266 Dealer Inquiries Invited Oroer Today Send check MO also accept Master Card Visa Models shipped 350 PSI carton via UPS Add $850 shipping han dling Florida residents add 5% sales tax diameter varied results shown Table 5 Tables 4 5 can easily see variations prop size can significantly affect motor power examples applied voltage held constant current increased prop size thus power increased illustrates rather graphic fashion relationship power input up point power out put increasing prop size power increase has associated dual con sequences rapid battery discharge high enough currents some risk motor brushes 5 For constant applied voltage slower motor turns higher current drain also evident Tables 4 5 Thus fast-moving plane effective propeller rpm creases due prop unloading cur rent demand drops Translation longer run ning time Conversely small prop turning high revs large slow-moving glidertype approaching static test conditions relatively higher current inefficient power utilization because prop slip ping example larger slowerturning prop speed reducer will make much better use available energy stored battery case current demand always drops flight its question much later test conditions used demon strations herein considered within reasonable range operating capability motors used except * values cases data taken very quickly higher current levels either known damaging sure did want find out other hand some data points power levels too low useful flight Nevertheless representations believed fair Again its relative performance parame ters absolute accuracy mat ters 6 The power input required motors turn given prop same rpm nearly same may surprising performance factor vividly shown accompanying graph compares power input 11 samples nine different motor types turning same 6 x 4 propeller same propeller eight 11 motors performed within ranges shown Table 6 Three motors considered removed enough trend excluded table removed inefficient power input watts 51 10000 rpm 70 11000 101 12000 information evident part propeller determines input power given rpm part motors used comparable efficiencyat least over reasonable op erating power range de signed last statement means power lost motor process doing its intended job about same motors lost power mostly form heatmore later Its interesting note the least efficient motors tested among costly middle-of-the-road occupied comparatively low-cost sleevebearing types some exceptions course efficient motors consume least power spinning given prop will run longest par ticular battery Names motors tests will supplied unless inquiier manufacturers involved 40 wing 15 25 Engines Dealers & Distributors Welcomed Phone 703 273-9593 FLYLINE MODELS INC PO Box 2136 Fairfax Virginia 22031 USA November 1983 171 magic Dragon Trainer Pre-Bui Price $9995 Engine Size 25 CU Wing Span 55 Radio 3 4 Channels balsa construction Ready fine sand cover Control surfaces hinged HalIco landing gear 5132 nose gear strut Fitted canopy Instruction booklet hardware included Five Other Models Available Send Now Free Brochure ctru~ Pre-BuIlt lrice $10995 Engine Size 40 Wing Span 52 Wing Area 614 sq Length 385/8 Weight 4 lbs Radio 4 Channels IN STOCK FOR IMMEDIATE SHIPMENT New 30 CID QUADRA $20950 New 22 CiD QUADRA $10950 Reg 22 QUADRA $10400 Brisighelia Fiywheei $12400 Rag 22 QUADRA POWER ASSEMBLY ONLY$0400 QUADRA REPAIR 000 pius parts Jim Messer ERCOUPEPLANS $2395 KIT $23995 Jim Messer TOMAHAWKPLANS $2395 KIT $25gg5 Jim Messer9BALLTRAINER PLANS 41895 KIT gggg BALSA BASSWOOD 1811 ajuesl 35% OFF Concept FLEET PLANS $2995 KIT 515995 COWL $1995 FLOATS 35115 scale core $1795 complete kit $3996 FLOATS 4W scalecores $2195 complete kit $4795 CECONiTE Product 10) OFF Sig J3 CUB KIT $12495 PLANS SUPER STEARMAN Godfrey $2895 STARDUSTER TOO h Brisighelia J-2 CUB Neiitz $2995 VOLKSPLANE Chicken Charlie $2395 COCKPIT KITS Tomahawk F4U1 Spitfire $2398 Ercoupe $2095 Stearman $2295 Citabria $2495 J3 Cub $2195 ME-lOg $2295 Fleet $2195 US Quadra FUEL TANKS16 ou $695 32 oz 5795 FIBERGLASS ARROW SHAFTS 5/10 s 32 long 0/$1000 24-Hour Service . Add $250 postage Send Bank Check Money Order JIM MESSERS QUALITY MODEL PRODUCTS 106 Valley View Dr Aliegany NY 14706 R/C Capitol offers worlds finest RC custom built-up RC scale aircraft Quarter Scala PlansEa 92495PP Quarter Scale Pertial KitsEn $95OOPP Quarter Scale Custom-Built DeluxEa $500OOPP Piper Pacer PA-20 89 Wingspan Piper Tn-Pacer PA-22 89 Wingspan DH-85 Leopard Moth 111 Wingspan DH80A Puss Moth 111 Wingspan Please send $100 self-addressed stamped envelope complete list HOBBY CAPITOL RIC ESt 1951 46 N Oak St Ventura CA 93001 805643-7616 e 642-8465 Distributors Finest Quality Built-Up A/C Aircraft Custome Built Ready-ToFly Radio Controlled Modal Airplanes Classic R/C Scale SGRAT LAK TII LT-50 Electric Motor 01 Cu Ifl equivelent gas engine displacement Send self-addressed stamped envelope catalog ap plication notes Leisure 11 Deerspringllrvine/CA 92714 readers think Im hung up small motors props allow pro vide some information bigger stuff Table 7 data limited admittedliy represents some unlikely unde sirable combinations point about props determining motor input power fur ther illustrated comparison Table 7 really stands out deserves further comment Im refer ring Astro 25 Astro 075 speed reducer both turning 9 00 rpm Remarkable isnt Whats catch None some considerations 25 operating well below its nor mal intended power level twice power level shown might say 25 being underutilized example other hand 075 system being very well used Its lighter weight lower cost could reasonably pushed mOch higher normal power capability 25 Whatever prop dictating power demand point Im making get Part 4 batteries youll see energy tanks must con sidered part big picturethe total Electric system picturewhere choice system component sort team choice Translation want run 9 x 6 8000 other motor/prop/rpm combination fly some plane some specific duration battery because practicalities cell size number cells charging considerations 2 Motor propeller plane efficiency data examples given part have nominal operating condi tions motor propeller mean operating conditions would representative good fly ing power levels Putting yet another way would conditions reasonably good efficiency motors props presented used suitable plane Efficiency power output divided power input always number less meaning get less out put difference wasted power mentioned earlier Another point made earlier electrical power put motor easily measured simply product motor input volt age wattage current Power outputrelated work done motor its propeller moving both air planeis easily measured Anyway efficiency curve has shape bit like hook clothes hanger maybe like climb level-off dive roller coaster means some power range maximizing efficiencythe place percentage power lost least information Ive seen peak actually rounded usually represents rather broad range good power utilization 172 Model Aviation motor/prop maY primary con sideration Power Soar New Heights other words dont have oper ating exactly very peak impossible maintain anyway enjoy lot great flying Far either side broad max imum region however operating ex tremes efficiency can terrible flight will also terrible what extremes low ends efficiency curve can come end low power levels ratio output power input power small because example much input power goes kinds losses shown Table Ithe no prop power used overcome friction etc Thus small amount power de livered prop may comparable less lost would almost al ways no-flight condition anyway saw power region very low wattage region indeed other end efficiency curve very high input power levels motor losses rise very rapidly due example heating area operation cur rent input very high such too much voltage applied too large prop used power lost heat rises rapidly because power product current times current times resistance commonly called squared R' losses resistance armature windings brush-tocommutator contact resistance brush material brush connection resistance big driver current times itself Thus under such conditions more current input lower lower percentage power output ef ficiency curve drops off sooner later motor may go belly up excess ive brush heat heating concern Ive alluded often comes few words motors currently use simply adaptations some readily available often imported standard low cost unit intended con sumer applications nothing wrong this allows variety low cost what can see appli cation model use probably tasks motors far other intended ap plication application feel putting motors past limits design intent experience first mani festation brush damage very high currents Anyway more motors becoming available have much better behavior regard other things parts continuing Elec tric evolution Later get planes stallations well look some actual exam ples operation some guidelines help assure longevity investment along lots enjoyable flying fun now should clear motor prop independent plane What can too much motor bench static may case air providing plane moves out quickly allowing prop unload As mentioned earlier motor turning small November 1983 173 prop fast slowly-moving glider-type inefficient potentially bad-for-themotor situation Now let describe ex ample thats similar other direc tion Ive twice occasion help someone ARF Kraft Shoestring tractive planes 05-sized motor six cells 06 Ah size nylon props 8 x 6 planes just sorta mushed along studying situation respect weight area etc seemed really should fly better changed prop nylon 7 x 6 did trick motor turned up faster expected drew less current motor-prop-plane combination now much better fact plane much fun fly Simple huh does know what may have realized clue solution came three paragraphs earlierlook back see Admittedly above discussions simplifications incomplete theres involved motor/prop/plane performance discussed far think weve gone far enough get general ideathat theres variety motors avail able work quite well prop choice power closely related good results efficient motor/plane/prop combination thats needed Well al subject must covered before can look what works well together WS 54 29 35 ENGINtS 3 CHANNEL THE BEGINNERS KITTEN AND EXPERTS TIGER Revolutionary snap-on wing eliminates bolts rnbber bands complete kit $54 95 dealer direct GEMINI MODELS INC PO Bn 1168 Pasc NJ 07055 topic comes up next month Batteries Remember promised two things basics things work intend keep commitment So far weve dealing mostly first part promise will seriously pursue Elec trics basics given will sooner later directly contribute success own Electric design choices part making guy mentioned Part 2 guy understands basics knows what to worksthe guy whos 'got together Electrics closing note first four parts series will have written before Part 1 reaches readers expect installment will raise questions Despite good inten tions know some things will overlooked some things will unclear can welcome critic regard Perhaps most-asked questions can collected answers presented read wrap-up installment meantime will endeavor responsive individuals expediently possible Please direct questions SASE author Bob Kopski 25 West End Dr Lansdale PA 19446 SAFE FLYING IS NO ACCIDENT SAM Champs/Mathews Continued page 81 really means something SAM types host chapter SAM No Contest Director Jim Thomas obviously done homework example fact no sooner mentioned nice would someone water down dusty access road water truck arrived did just process repeated two three times daily Although no hookups available campers motor homes contest site sev eral self-contained vehicles well tenters campers stayed ovemight site Motel ar rangements well-handled Tanya Baird Chamber Commerce office available room LaJunta reserved mid-April attendees found accommodations nearby towns Rates very reasonable Ad ditional rooms available Otero Junior Col lege stayed reported clean air-conditioned facilities lots bull ses sions progress times lounge area concessionaire provided food drink flying fieldagain very reasonable prices However breakfast Laiunta proved bit hassle sudden influx hungry modelers demanding breakfast 600 am overtaxed staffs local restaurants making rather slow service fact some eateries didnt open until 700 am seems real crux problem contest manage ments decision start flying 800 rather originally-announced time 900 am scheduling change made order get competition over hour earlierto get out heat As matter fact since LaJunta far eastern edge Mountain timezone flying could have scheduled start 600 am contest day could have ended early 300 pm Go Upty Up-Up Problems effect high altitude engine power glide models didnt seem severe anticipated Although power-loss certainly factor major problems seemed i/A reed-valve engines Texaco event Climbouts certainly lower slower peculiar distribution lift atmosphere real oddity saw As repeatedly observed lift existed strata model would riding rather large boomer another plane immediately below above would downer Ther mal pattems much like seen Lake Charles LA accustomed finding Great Plains 174 Model Aviation product can recommendSUPER HAND SAN DER Dealers & Distributors Wanted confidenceHOBBIESTSee Hobby Dealer Call Art Gross Enterprises HOBBY DEALERCa// Distributor 06/743-9332 ART GROSS ENTERPRISES 12516 MAPLEWOOD AVE EDMONDS WA 98020 DUAL PERSONAUTY TRAINER GEENIS BEAUTIFULI SUPER CHAMP [F6T\F1 Invited Liti IjI.u Inc Dealer inquiries High pert onnante model engine connecting rods connecting rods made tha beat materials available designed give long service eliminate rod breakage modern high-Peef mance model engines Used leading aircraft boat car racers hobbyists Rods available popular model engines Look RPM new innovative products wish proven performance records Richardson Precision Machining Inc 5070 Golden Dr San Jose cA 5612914061 2S7-7068
Edition: Model Aviation - 1983/11
Page Numbers: 93, 94, 95, 170, 171, 172, 173, 174
This authors testing setup evaluation motors props results shown tables discussed text power supply fully adjustable zero 30 volts up 20 amperes two digital readouts motor voltage current analog meter tachometer optical pickup remotely located under motor mount Light source also remotely located Photos author THE FIRST INSTALLMENT series September issue described some pros cons electric-powered models last month covered motors use Some basic aspects motors de scribed practical considerations covered Earlier asked have faith read daringly onward remind because realize subject part may appear both simple some strange others However think some up coming information will surprising interesting manyand perhaps little confusing ditficult others first reading still others some what fol lows may downright boring seem totally irrelevant taken alone section however combined ether parts series will provide very intimate overall feel exactly what \Ki O iOE ra popellor rave electricpowered models yoi re new Electrics authors test results may astound second reading may required fully grasp some points thai made that1s what takes suggest Part 3 November 1983 93 goes motor battery pro peller given planeand affect flight results get other words series continues will come together' encourage un daunted continuance series Im sure will find worthwhile presentation seems too slow 80 70 60 -50 40 -8 tedious remern ber introduction Electricson installment plan Its necessarily easy installment plan either read write Hox ever maintain subject can generally simple oc t V 0 0 0 ----V e Lu 0 0 0 0 0 -I C V e 0 V C 0 0 RPM X 1000 91011 SC V0 certainly successful though neces sadly short Perhaps some readers have disap pointments Electrics just because some details made light glossed over elsewhere Thats Model Avi ation has planned seriesto make sure adequate introductory treatment such anyone wants can very successful Electric flier theres some useful stuff Gas guys honest well-intended series cannot complete detail-perfect several reasons dont know everything Another Im trying se lect meaningful useful offer ings consistent limitations pub lication space presentation time can fact best can can criticautomaticallyby asking questions 1 Propellers power Now Chave seen some Electric models Part have some introductory insight motors Part 2 could wondering what business concerning power heating performance about Lets look what happens motor required its thingturn prop power plane leading suppliers Electric flight systems provide instructions regarding choice model size weight suit able propellers things will also addressed another part series meantime get good feel motor operation propellers power lets look things static environment ie bench rather flight experience excellent correlation tween what observe bench what experience air A Power inputno prop Electrical power product electric potential volts electric current amps case motor input power motor terminal voltage times motor terminal input current amperage product V x power watts power comes frm energy 12131415 tank battery tank specific size can deliver its fill Part 4 will cover batteries detail discuss much tanks' can deliver Now however going get feel just Shown motor input power various motor speeds rpm 11 samples nine different motor types swinging Cox 6-4 gray prop Note different symbol 11 motors Connect like symbols form smooth performance curves through various speeds Note generally tight clusters data points throughout range test 94 Model Aviation Table 1 Typical Motor Power InputNo Prop MotorVoltsAmpsWatts Astro 0560075450 p/n 210770078546 80081648 90084756 Leisure LT-5050119595 Pattern Wind60124744 7013091 Mabuchi5011859 RS540S65276013078 70146102 80153122 Table 2 Performance Variation Various Same Size Props Propeller 64AmpsWatts Top Flite Nylon1168113300 Top Flite Wood13393112700 Cox Gray155*10912200 Table 3 Typical Motor/Propeller Performance Voltage Variation VoltsAmpsWattsRPM 60795488000 65905598550 70100709050 75110839600 801219710000 8513011110500 133 120 110 100 90 much fuel used motors next month youll have appreciation Part 4 As mentioned earlier motor running no prop draws small amount current sufficient overcome losses due friction other things illustrate sev eral examples shown Table measurements made using test setup pictured Notice something particular about data Table example motor current increase large crease voltage caused will case prop measurements tests made using convenient adjustable power supply exactly same re sults would occur motor bat tery interested power supply pictured capable up 30 volts 20 amps has remote voltage sense assure correct voltage motor terminals Also has adjustable current limit dont have accident during some zealous data run power capa bility may sound impressive believe expect need capability near future point want make special note has experience Ive told same Electric flight system suppliers performance production flight motors varies about plus-or-minus 10% As youll also see props also vary greatly load present motor battery course measurement motor performance has instrumentation accuracy associated Thus rea sons apparent differences Electric flight experience can occur Em noting now just case anyone reading has has read about different results B Power inputwith props ifl tables various motor performance mea surements different props ahown Whats mportant absoLve ac curacy relative performances -i particuiar notice bow rapidly input power changes tbattery voltage dra matic eFfect piop size can hae youll see important use right prop temptation just stick bigger prop add another cell may have carefully con sidered What seems like small change may fact either present unbearable load motor lest cause decline power system efficiency Remember static demonstrations motor/prop moving forward actual flying condi tions aircraft speed etc can have signifi cant influence data 1 All propellers same size necessarily created equal demonstrate ran Leisure LT-50 Pattern Wind very nicely-made motor three different 6 X 4 props applied voltage held constant 70 volts much like battery would hold nearly-constant voltage Table 2 lists resulting current drain input power rpm Notice wide variation power input roughly translates about same variation power output flight per formance might inclined say prop better prop remember dont get something nothing output performance input power means faster battery dis charge shorter flight timealthough increased flight performance may very well worth depending plane want fly some simi larity running engine full bore vs half throttle latter goes longer tank fuel Does Cox 6 x 4 gray fly aerobatic Jack Rabbit hotter Top Flight 6 x 4 nylon betcha buddy gives shorter flight too 2 A small change voltage makes big change performance demon strate propped Mabuchi Continued page 170 November 1983 95 Table 4 Effect Propeller Pitch Motor Input Power PropAmpsWattsRPM 8-468487950 8-580567550 8-696677000 8-8117826200 Table 5 Effect Prop Diameter Motor Input Power PropAmpsWattsRPM 6-437269000 7-450358400 8-469487900 Table 7 Some Larger Motor/Prop/Power Demonstrations MotorPropRPMPower Astro 259-6 wood700086 watts Astro 109-6 wood700090 watts Astro 075* *9-6 wood700080 watts Astro 259-6 wood8000126 watts Astro 075* *9-6 wood8000115 watts Astro 2512-6 wood5100115 watts Astrol5**12-6wood510096watts Now 1 ** means motors used matching speed reducers 2 In cases motor clearly over-propped operating conditions carefully controlled no risk motor involved 3 No voltages currents givenonly product power voltages currents generally well removed values would considered normal motor its normal prop Consider above academic exercises necessarily practical cases Table 6 Input Power Given 6-3 Prop Specific RPM RPM100001100012000 Watts44/360/S77 16 Close-up motor being tested Power motor supplied through cables connector extreme left Two test clip connections provide remote sensing precise control applied voltage Wood V-block underneath motor has rubber padding conjunction rubberbands stretched across top provide sturdy mount hold largest motors intended models NOW THERES QUICK AND EASY WAY OF ClEANING YOUR MODEL CRAFTS Super-K Model Cleaner Remaves fu Residue dirt contact1 CEJTS ClEANING TiME IN HALF Just spray model solvent wtpe soft cloth paper towel SIMPLE AS THAT Leaves craft showcase cleani eWoni hami Pahits Coverings Dries clew fast Eminates Ihe WOk cleaning model Strong Professonal Quality formula Great Model Craft Scots manes Helicopters Cleans Gently Protects delicate model DEALERS WANTED DOMESTIC & OVERSEAS WE EXPORT Hurry Have product shelves time Christmas guaranteed top seller Sugg retail $550 per gallon Contact us price structures ordering Information Also ask about other Super-K products Model Industry Ale Manufacturers & Major Brands DIstributors Model Engines Kits Radios & Accessories Super-K brand Kings RadIo Control Hobbles International 3960 West 16th Ave Hlaleah Florida 33012 Phone 305 557-2024 SS NEW * NEW * NEW BUY ECONO-PAC & SAVE WACO HKS-1GREAT LAKES TRAINER GREAT LAKES SPECIAL2T1A/2T1E PLAN$27OOppPLAN$27ttpp PG Cowl$27OOpp FG Cowl527OOpp F G Pants$25ttpp ECONO PAC$49OOpp ECOND-PACS70OOpp SAVE$600 SAVE $900 Parisian Moustique pian$17OOpp -. mixture reed valve todays ubiqui tous Cox 1/2As meetings interested modelers Brown delights producing engine pocket flash dis assembling spreading its parts out table before amazed onlookers Without too much prodding hell also demonstrate still operates just well day built Among pictures two fine examples 60 cu Brown Junior prototypes handbuilt Brown late 1931 early 1932 Both engine number A2 A5 share same basic characteristics though differ pther minor detail example like common production Browns later years engine A2 discharges its spent gases directly through tour D-shaped exhaust ports cut rear cylinder just above intake manifold engine A5 however exhaust ports concealed exhaust manifold two round threaded out lets Brown made least other engine manitolded like additional touch spark plug offset horizontally rear Incidentally both engines A2 A5 have steel pistons fitted curious ar rangement two cast iron piston rings dif ferent widthsan upper narrow com pression ring above lower very wide oil ring Note very short flared intake tubes sandcast crankcases handmade spark plugs common both early engines Max Bassetts Brown Junior number A17 manufactured Walter Hurleman Brown developed engines first pro duction tooling early summer 1932 different edge contour en gines bypass cover intake manifold indi cates parts die-stamped rather hand-formed engines A2 A5 intake tube also longer slightly larger diameter engine other 40 50 A-model Brown Juniors Hurleman said have produced before Bill Brown parted company late 1933 first have ringless precision-ground steel pistons remained hallmark qual ity model engines years afterward minor changes Hurleman continued manufacture limited quantities engine under own name until 1937 1938 Meanwhile Junior Motors Corporation organized early 1934 Bill Brown began oversee production yet another Brown Juniorthe 1934 model Bwhile still sophomore Penn State Financed Edward Roberts Philadelphia bankers son actually ran company Junior Motors turned out 50000 Brown engines before ceasing production eight years later Roberts served AMAs third president 1939 through 1942 hobbys earliest promoters Radio Control RS550S6530 good inexpensive hard-toget motor Top Flite 7 x 6 nylon Table 3 shows what happens input current input power rpm voltage varied test voltage range chosen might easily represent battery behavior just-off-charge through its useful Electrics/Kopski Continued page 95 run-down Notice dramatic power change Again static behavior shown table indication flight behavior Yes Electric noticeably hotter right after charge Ni-Cds characteristically drop initial high terminal voltage rapidly slowly decline through long plateau finally drop dramatically end-ofcharge Thats plane flies too Ive always feeling some suppliers ad vertise products performance right charge peak 3 For given propeller small change rpm representative significant change power/performance other key piece information evident Table 3 Dont treat few hundred rpm change disregard works Gas too seemingly small change tach ometer reading can indeed significant tachometer accuracy youre comparing results others Now well look implications changing prop size both diameter pitch 4 Variation prop size has signifi cant effect power performance demonstrate used favorite motors older version Astro 075 motor powered constant 70 volts propellers used Top Flite wood Labeled size assumed accurate First diameter held constant pitch varied results shown Table 4 pitch held constant 170 Model Aviation 4-STROKE ENGINE SALE COMPARE & SAVE OSFS4O8950 OSFS6O12500 OS ES 7514500 OS ES 1 20T34900 ENYA4O-4C 50 ENYA6O-4C- -14950 ENYA9O-4C 950 SAITO 308450 SAITO 40-Il9950 SAITO4510950 SAITO 90T29950 TERMS Prepald check money order Include $250 UPS avid street address Calif residents add 6% sales tax No credit cards please Allow 2 weeks delivery REDWOOD hobby Imports PO BOX 6171 SANTA ROSA CALIF 95401 Sublect stock hand Designers Builders Fine PRE-BUILT RIC Models Fire Fox Pre-Built Price $12495 Engine Size 40 cu Wing Span 521A Radio 4 Channels balsa construction Ready fine sand covpr Control surfaces hinged Has bolt-on wing HalIco landing gear ABS wheel pants mounted axels stalled Fitted canopy Instruction booklet hardware included ERO 3850 US Hwy 19 No Palm Harbor FL 33463 ECH RIC813 938-3266 Dealer Inquiries Invited Oroer Today Send check MO also accept Master Card Visa Models shipped 350 PSI carton via UPS Add $850 shipping han dling Florida residents add 5% sales tax diameter varied results shown Table 5 Tables 4 5 can easily see variations prop size can significantly affect motor power examples applied voltage held constant current increased prop size thus power increased illustrates rather graphic fashion relationship power input up point power out put increasing prop size power increase has associated dual con sequences rapid battery discharge high enough currents some risk motor brushes 5 For constant applied voltage slower motor turns higher current drain also evident Tables 4 5 Thus fast-moving plane effective propeller rpm creases due prop unloading cur rent demand drops Translation longer run ning time Conversely small prop turning high revs large slow-moving glidertype approaching static test conditions relatively higher current inefficient power utilization because prop slip ping example larger slowerturning prop speed reducer will make much better use available energy stored battery case current demand always drops flight its question much later test conditions used demon strations herein considered within reasonable range operating capability motors used except * values cases data taken very quickly higher current levels either known damaging sure did want find out other hand some data points power levels too low useful flight Nevertheless representations believed fair Again its relative performance parame ters absolute accuracy mat ters 6 The power input required motors turn given prop same rpm nearly same may surprising performance factor vividly shown accompanying graph compares power input 11 samples nine different motor types turning same 6 x 4 propeller same propeller eight 11 motors performed within ranges shown Table 6 Three motors considered removed enough trend excluded table removed inefficient power input watts 51 10000 rpm 70 11000 101 12000 information evident part propeller determines input power given rpm part motors used comparable efficiencyat least over reasonable op erating power range de signed last statement means power lost motor process doing its intended job about same motors lost power mostly form heatmore later Its interesting note the least efficient motors tested among costly middle-of-the-road occupied comparatively low-cost sleevebearing types some exceptions course efficient motors consume least power spinning given prop will run longest par ticular battery Names motors tests will supplied unless inquiier manufacturers involved 40 wing 15 25 Engines Dealers & Distributors Welcomed Phone 703 273-9593 FLYLINE MODELS INC PO Box 2136 Fairfax Virginia 22031 USA November 1983 171 magic Dragon Trainer Pre-Bui Price $9995 Engine Size 25 CU Wing Span 55 Radio 3 4 Channels balsa construction Ready fine sand cover Control surfaces hinged HalIco landing gear 5132 nose gear strut Fitted canopy Instruction booklet hardware included Five Other Models Available Send Now Free Brochure ctru~ Pre-BuIlt lrice $10995 Engine Size 40 Wing Span 52 Wing Area 614 sq Length 385/8 Weight 4 lbs Radio 4 Channels IN STOCK FOR IMMEDIATE SHIPMENT New 30 CID QUADRA $20950 New 22 CiD QUADRA $10950 Reg 22 QUADRA $10400 Brisighelia Fiywheei $12400 Rag 22 QUADRA POWER ASSEMBLY ONLY$0400 QUADRA REPAIR 000 pius parts Jim Messer ERCOUPEPLANS $2395 KIT $23995 Jim Messer TOMAHAWKPLANS $2395 KIT $25gg5 Jim Messer9BALLTRAINER PLANS 41895 KIT gggg BALSA BASSWOOD 1811 ajuesl 35% OFF Concept FLEET PLANS $2995 KIT 515995 COWL $1995 FLOATS 35115 scale core $1795 complete kit $3996 FLOATS 4W scalecores $2195 complete kit $4795 CECONiTE Product 10) OFF Sig J3 CUB KIT $12495 PLANS SUPER STEARMAN Godfrey $2895 STARDUSTER TOO h Brisighelia J-2 CUB Neiitz $2995 VOLKSPLANE Chicken Charlie $2395 COCKPIT KITS Tomahawk F4U1 Spitfire $2398 Ercoupe $2095 Stearman $2295 Citabria $2495 J3 Cub $2195 ME-lOg $2295 Fleet $2195 US Quadra FUEL TANKS16 ou $695 32 oz 5795 FIBERGLASS ARROW SHAFTS 5/10 s 32 long 0/$1000 24-Hour Service . Add $250 postage Send Bank Check Money Order JIM MESSERS QUALITY MODEL PRODUCTS 106 Valley View Dr Aliegany NY 14706 R/C Capitol offers worlds finest RC custom built-up RC scale aircraft Quarter Scala PlansEa 92495PP Quarter Scale Pertial KitsEn $95OOPP Quarter Scale Custom-Built DeluxEa $500OOPP Piper Pacer PA-20 89 Wingspan Piper Tn-Pacer PA-22 89 Wingspan DH-85 Leopard Moth 111 Wingspan DH80A Puss Moth 111 Wingspan Please send $100 self-addressed stamped envelope complete list HOBBY CAPITOL RIC ESt 1951 46 N Oak St Ventura CA 93001 805643-7616 e 642-8465 Distributors Finest Quality Built-Up A/C Aircraft Custome Built Ready-ToFly Radio Controlled Modal Airplanes Classic R/C Scale SGRAT LAK TII LT-50 Electric Motor 01 Cu Ifl equivelent gas engine displacement Send self-addressed stamped envelope catalog ap plication notes Leisure 11 Deerspringllrvine/CA 92714 readers think Im hung up small motors props allow pro vide some information bigger stuff Table 7 data limited admittedliy represents some unlikely unde sirable combinations point about props determining motor input power fur ther illustrated comparison Table 7 really stands out deserves further comment Im refer ring Astro 25 Astro 075 speed reducer both turning 9 00 rpm Remarkable isnt Whats catch None some considerations 25 operating well below its nor mal intended power level twice power level shown might say 25 being underutilized example other hand 075 system being very well used Its lighter weight lower cost could reasonably pushed mOch higher normal power capability 25 Whatever prop dictating power demand point Im making get Part 4 batteries youll see energy tanks must con sidered part big picturethe total Electric system picturewhere choice system component sort team choice Translation want run 9 x 6 8000 other motor/prop/rpm combination fly some plane some specific duration battery because practicalities cell size number cells charging considerations 2 Motor propeller plane efficiency data examples given part have nominal operating condi tions motor propeller mean operating conditions would representative good fly ing power levels Putting yet another way would conditions reasonably good efficiency motors props presented used suitable plane Efficiency power output divided power input always number less meaning get less out put difference wasted power mentioned earlier Another point made earlier electrical power put motor easily measured simply product motor input volt age wattage current Power outputrelated work done motor its propeller moving both air planeis easily measured Anyway efficiency curve has shape bit like hook clothes hanger maybe like climb level-off dive roller coaster means some power range maximizing efficiencythe place percentage power lost least information Ive seen peak actually rounded usually represents rather broad range good power utilization 172 Model Aviation motor/prop maY primary con sideration Power Soar New Heights other words dont have oper ating exactly very peak impossible maintain anyway enjoy lot great flying Far either side broad max imum region however operating ex tremes efficiency can terrible flight will also terrible what extremes low ends efficiency curve can come end low power levels ratio output power input power small because example much input power goes kinds losses shown Table Ithe no prop power used overcome friction etc Thus small amount power de livered prop may comparable less lost would almost al ways no-flight condition anyway saw power region very low wattage region indeed other end efficiency curve very high input power levels motor losses rise very rapidly due example heating area operation cur rent input very high such too much voltage applied too large prop used power lost heat rises rapidly because power product current times current times resistance commonly called squared R' losses resistance armature windings brush-tocommutator contact resistance brush material brush connection resistance big driver current times itself Thus under such conditions more current input lower lower percentage power output ef ficiency curve drops off sooner later motor may go belly up excess ive brush heat heating concern Ive alluded often comes few words motors currently use simply adaptations some readily available often imported standard low cost unit intended con sumer applications nothing wrong this allows variety low cost what can see appli cation model use probably tasks motors far other intended ap plication application feel putting motors past limits design intent experience first mani festation brush damage very high currents Anyway more motors becoming available have much better behavior regard other things parts continuing Elec tric evolution Later get planes stallations well look some actual exam ples operation some guidelines help assure longevity investment along lots enjoyable flying fun now should clear motor prop independent plane What can too much motor bench static may case air providing plane moves out quickly allowing prop unload As mentioned earlier motor turning small November 1983 173 prop fast slowly-moving glider-type inefficient potentially bad-for-themotor situation Now let describe ex ample thats similar other direc tion Ive twice occasion help someone ARF Kraft Shoestring tractive planes 05-sized motor six cells 06 Ah size nylon props 8 x 6 planes just sorta mushed along studying situation respect weight area etc seemed really should fly better changed prop nylon 7 x 6 did trick motor turned up faster expected drew less current motor-prop-plane combination now much better fact plane much fun fly Simple huh does know what may have realized clue solution came three paragraphs earlierlook back see Admittedly above discussions simplifications incomplete theres involved motor/prop/plane performance discussed far think weve gone far enough get general ideathat theres variety motors avail able work quite well prop choice power closely related good results efficient motor/plane/prop combination thats needed Well al subject must covered before can look what works well together WS 54 29 35 ENGINtS 3 CHANNEL THE BEGINNERS KITTEN AND EXPERTS TIGER Revolutionary snap-on wing eliminates bolts rnbber bands complete kit $54 95 dealer direct GEMINI MODELS INC PO Bn 1168 Pasc NJ 07055 topic comes up next month Batteries Remember promised two things basics things work intend keep commitment So far weve dealing mostly first part promise will seriously pursue Elec trics basics given will sooner later directly contribute success own Electric design choices part making guy mentioned Part 2 guy understands basics knows what to worksthe guy whos 'got together Electrics closing note first four parts series will have written before Part 1 reaches readers expect installment will raise questions Despite good inten tions know some things will overlooked some things will unclear can welcome critic regard Perhaps most-asked questions can collected answers presented read wrap-up installment meantime will endeavor responsive individuals expediently possible Please direct questions SASE author Bob Kopski 25 West End Dr Lansdale PA 19446 SAFE FLYING IS NO ACCIDENT SAM Champs/Mathews Continued page 81 really means something SAM types host chapter SAM No Contest Director Jim Thomas obviously done homework example fact no sooner mentioned nice would someone water down dusty access road water truck arrived did just process repeated two three times daily Although no hookups available campers motor homes contest site sev eral self-contained vehicles well tenters campers stayed ovemight site Motel ar rangements well-handled Tanya Baird Chamber Commerce office available room LaJunta reserved mid-April attendees found accommodations nearby towns Rates very reasonable Ad ditional rooms available Otero Junior Col lege stayed reported clean air-conditioned facilities lots bull ses sions progress times lounge area concessionaire provided food drink flying fieldagain very reasonable prices However breakfast Laiunta proved bit hassle sudden influx hungry modelers demanding breakfast 600 am overtaxed staffs local restaurants making rather slow service fact some eateries didnt open until 700 am seems real crux problem contest manage ments decision start flying 800 rather originally-announced time 900 am scheduling change made order get competition over hour earlierto get out heat As matter fact since LaJunta far eastern edge Mountain timezone flying could have scheduled start 600 am contest day could have ended early 300 pm Go Upty Up-Up Problems effect high altitude engine power glide models didnt seem severe anticipated Although power-loss certainly factor major problems seemed i/A reed-valve engines Texaco event Climbouts certainly lower slower peculiar distribution lift atmosphere real oddity saw As repeatedly observed lift existed strata model would riding rather large boomer another plane immediately below above would downer Ther mal pattems much like seen Lake Charles LA accustomed finding Great Plains 174 Model Aviation product can recommendSUPER HAND SAN DER Dealers & Distributors Wanted confidenceHOBBIESTSee Hobby Dealer Call Art Gross Enterprises HOBBY DEALERCa// Distributor 06/743-9332 ART GROSS ENTERPRISES 12516 MAPLEWOOD AVE EDMONDS WA 98020 DUAL PERSONAUTY TRAINER GEENIS BEAUTIFULI SUPER CHAMP [F6T\F1 Invited Liti IjI.u Inc Dealer inquiries High pert onnante model engine connecting rods connecting rods made tha beat materials available designed give long service eliminate rod breakage modern high-Peef mance model engines Used leading aircraft boat car racers hobbyists Rods available popular model engines Look RPM new innovative products wish proven performance records Richardson Precision Machining Inc 5070 Golden Dr San Jose cA 5612914061 2S7-7068
Edition: Model Aviation - 1983/11
Page Numbers: 93, 94, 95, 170, 171, 172, 173, 174
This authors testing setup evaluation motors props results shown tables discussed text power supply fully adjustable zero 30 volts up 20 amperes two digital readouts motor voltage current analog meter tachometer optical pickup remotely located under motor mount Light source also remotely located Photos author THE FIRST INSTALLMENT series September issue described some pros cons electric-powered models last month covered motors use Some basic aspects motors de scribed practical considerations covered Earlier asked have faith read daringly onward remind because realize subject part may appear both simple some strange others However think some up coming information will surprising interesting manyand perhaps little confusing ditficult others first reading still others some what fol lows may downright boring seem totally irrelevant taken alone section however combined ether parts series will provide very intimate overall feel exactly what \Ki O iOE ra popellor rave electricpowered models yoi re new Electrics authors test results may astound second reading may required fully grasp some points thai made that1s what takes suggest Part 3 November 1983 93 goes motor battery pro peller given planeand affect flight results get other words series continues will come together' encourage un daunted continuance series Im sure will find worthwhile presentation seems too slow 80 70 60 -50 40 -8 tedious remern ber introduction Electricson installment plan Its necessarily easy installment plan either read write Hox ever maintain subject can generally simple oc t V 0 0 0 ----V e Lu 0 0 0 0 0 -I C V e 0 V C 0 0 RPM X 1000 91011 SC V0 certainly successful though neces sadly short Perhaps some readers have disap pointments Electrics just because some details made light glossed over elsewhere Thats Model Avi ation has planned seriesto make sure adequate introductory treatment such anyone wants can very successful Electric flier theres some useful stuff Gas guys honest well-intended series cannot complete detail-perfect several reasons dont know everything Another Im trying se lect meaningful useful offer ings consistent limitations pub lication space presentation time can fact best can can criticautomaticallyby asking questions 1 Propellers power Now Chave seen some Electric models Part have some introductory insight motors Part 2 could wondering what business concerning power heating performance about Lets look what happens motor required its thingturn prop power plane leading suppliers Electric flight systems provide instructions regarding choice model size weight suit able propellers things will also addressed another part series meantime get good feel motor operation propellers power lets look things static environment ie bench rather flight experience excellent correlation tween what observe bench what experience air A Power inputno prop Electrical power product electric potential volts electric current amps case motor input power motor terminal voltage times motor terminal input current amperage product V x power watts power comes frm energy 12131415 tank battery tank specific size can deliver its fill Part 4 will cover batteries detail discuss much tanks' can deliver Now however going get feel just Shown motor input power various motor speeds rpm 11 samples nine different motor types swinging Cox 6-4 gray prop Note different symbol 11 motors Connect like symbols form smooth performance curves through various speeds Note generally tight clusters data points throughout range test 94 Model Aviation Table 1 Typical Motor Power InputNo Prop MotorVoltsAmpsWatts Astro 0560075450 p/n 210770078546 80081648 90084756 Leisure LT-5050119595 Pattern Wind60124744 7013091 Mabuchi5011859 RS540S65276013078 70146102 80153122 Table 2 Performance Variation Various Same Size Props Propeller 64AmpsWatts Top Flite Nylon1168113300 Top Flite Wood13393112700 Cox Gray155*10912200 Table 3 Typical Motor/Propeller Performance Voltage Variation VoltsAmpsWattsRPM 60795488000 65905598550 70100709050 75110839600 801219710000 8513011110500 133 120 110 100 90 much fuel used motors next month youll have appreciation Part 4 As mentioned earlier motor running no prop draws small amount current sufficient overcome losses due friction other things illustrate sev eral examples shown Table measurements made using test setup pictured Notice something particular about data Table example motor current increase large crease voltage caused will case prop measurements tests made using convenient adjustable power supply exactly same re sults would occur motor bat tery interested power supply pictured capable up 30 volts 20 amps has remote voltage sense assure correct voltage motor terminals Also has adjustable current limit dont have accident during some zealous data run power capa bility may sound impressive believe expect need capability near future point want make special note has experience Ive told same Electric flight system suppliers performance production flight motors varies about plus-or-minus 10% As youll also see props also vary greatly load present motor battery course measurement motor performance has instrumentation accuracy associated Thus rea sons apparent differences Electric flight experience can occur Em noting now just case anyone reading has has read about different results B Power inputwith props ifl tables various motor performance mea surements different props ahown Whats mportant absoLve ac curacy relative performances -i particuiar notice bow rapidly input power changes tbattery voltage dra matic eFfect piop size can hae youll see important use right prop temptation just stick bigger prop add another cell may have carefully con sidered What seems like small change may fact either present unbearable load motor lest cause decline power system efficiency Remember static demonstrations motor/prop moving forward actual flying condi tions aircraft speed etc can have signifi cant influence data 1 All propellers same size necessarily created equal demonstrate ran Leisure LT-50 Pattern Wind very nicely-made motor three different 6 X 4 props applied voltage held constant 70 volts much like battery would hold nearly-constant voltage Table 2 lists resulting current drain input power rpm Notice wide variation power input roughly translates about same variation power output flight per formance might inclined say prop better prop remember dont get something nothing output performance input power means faster battery dis charge shorter flight timealthough increased flight performance may very well worth depending plane want fly some simi larity running engine full bore vs half throttle latter goes longer tank fuel Does Cox 6 x 4 gray fly aerobatic Jack Rabbit hotter Top Flight 6 x 4 nylon betcha buddy gives shorter flight too 2 A small change voltage makes big change performance demon strate propped Mabuchi Continued page 170 November 1983 95 Table 4 Effect Propeller Pitch Motor Input Power PropAmpsWattsRPM 8-468487950 8-580567550 8-696677000 8-8117826200 Table 5 Effect Prop Diameter Motor Input Power PropAmpsWattsRPM 6-437269000 7-450358400 8-469487900 Table 7 Some Larger Motor/Prop/Power Demonstrations MotorPropRPMPower Astro 259-6 wood700086 watts Astro 109-6 wood700090 watts Astro 075* *9-6 wood700080 watts Astro 259-6 wood8000126 watts Astro 075* *9-6 wood8000115 watts Astro 2512-6 wood5100115 watts Astrol5**12-6wood510096watts Now 1 ** means motors used matching speed reducers 2 In cases motor clearly over-propped operating conditions carefully controlled no risk motor involved 3 No voltages currents givenonly product power voltages currents generally well removed values would considered normal motor its normal prop Consider above academic exercises necessarily practical cases Table 6 Input Power Given 6-3 Prop Specific RPM RPM100001100012000 Watts44/360/S77 16 Close-up motor being tested Power motor supplied through cables connector extreme left Two test clip connections provide remote sensing precise control applied voltage Wood V-block underneath motor has rubber padding conjunction rubberbands stretched across top provide sturdy mount hold largest motors intended models NOW THERES QUICK AND EASY WAY OF ClEANING YOUR MODEL CRAFTS Super-K Model Cleaner Remaves fu Residue dirt contact1 CEJTS ClEANING TiME IN HALF Just spray model solvent wtpe soft cloth paper towel SIMPLE AS THAT Leaves craft showcase cleani eWoni hami Pahits Coverings Dries clew fast Eminates Ihe WOk cleaning model Strong Professonal Quality formula Great Model Craft Scots manes Helicopters Cleans Gently Protects delicate model DEALERS WANTED DOMESTIC & OVERSEAS WE EXPORT Hurry Have product shelves time Christmas guaranteed top seller Sugg retail $550 per gallon Contact us price structures ordering Information Also ask about other Super-K products Model Industry Ale Manufacturers & Major Brands DIstributors Model Engines Kits Radios & Accessories Super-K brand Kings RadIo Control Hobbles International 3960 West 16th Ave Hlaleah Florida 33012 Phone 305 557-2024 SS NEW * NEW * NEW BUY ECONO-PAC & SAVE WACO HKS-1GREAT LAKES TRAINER GREAT LAKES SPECIAL2T1A/2T1E PLAN$27OOppPLAN$27ttpp PG Cowl$27OOpp FG Cowl527OOpp F G Pants$25ttpp ECONO PAC$49OOpp ECOND-PACS70OOpp SAVE$600 SAVE $900 Parisian Moustique pian$17OOpp -. mixture reed valve todays ubiqui tous Cox 1/2As meetings interested modelers Brown delights producing engine pocket flash dis assembling spreading its parts out table before amazed onlookers Without too much prodding hell also demonstrate still operates just well day built Among pictures two fine examples 60 cu Brown Junior prototypes handbuilt Brown late 1931 early 1932 Both engine number A2 A5 share same basic characteristics though differ pther minor detail example like common production Browns later years engine A2 discharges its spent gases directly through tour D-shaped exhaust ports cut rear cylinder just above intake manifold engine A5 however exhaust ports concealed exhaust manifold two round threaded out lets Brown made least other engine manitolded like additional touch spark plug offset horizontally rear Incidentally both engines A2 A5 have steel pistons fitted curious ar rangement two cast iron piston rings dif ferent widthsan upper narrow com pression ring above lower very wide oil ring Note very short flared intake tubes sandcast crankcases handmade spark plugs common both early engines Max Bassetts Brown Junior number A17 manufactured Walter Hurleman Brown developed engines first pro duction tooling early summer 1932 different edge contour en gines bypass cover intake manifold indi cates parts die-stamped rather hand-formed engines A2 A5 intake tube also longer slightly larger diameter engine other 40 50 A-model Brown Juniors Hurleman said have produced before Bill Brown parted company late 1933 first have ringless precision-ground steel pistons remained hallmark qual ity model engines years afterward minor changes Hurleman continued manufacture limited quantities engine under own name until 1937 1938 Meanwhile Junior Motors Corporation organized early 1934 Bill Brown began oversee production yet another Brown Juniorthe 1934 model Bwhile still sophomore Penn State Financed Edward Roberts Philadelphia bankers son actually ran company Junior Motors turned out 50000 Brown engines before ceasing production eight years later Roberts served AMAs third president 1939 through 1942 hobbys earliest promoters Radio Control RS550S6530 good inexpensive hard-toget motor Top Flite 7 x 6 nylon Table 3 shows what happens input current input power rpm voltage varied test voltage range chosen might easily represent battery behavior just-off-charge through its useful Electrics/Kopski Continued page 95 run-down Notice dramatic power change Again static behavior shown table indication flight behavior Yes Electric noticeably hotter right after charge Ni-Cds characteristically drop initial high terminal voltage rapidly slowly decline through long plateau finally drop dramatically end-ofcharge Thats plane flies too Ive always feeling some suppliers ad vertise products performance right charge peak 3 For given propeller small change rpm representative significant change power/performance other key piece information evident Table 3 Dont treat few hundred rpm change disregard works Gas too seemingly small change tach ometer reading can indeed significant tachometer accuracy youre comparing results others Now well look implications changing prop size both diameter pitch 4 Variation prop size has signifi cant effect power performance demonstrate used favorite motors older version Astro 075 motor powered constant 70 volts propellers used Top Flite wood Labeled size assumed accurate First diameter held constant pitch varied results shown Table 4 pitch held constant 170 Model Aviation 4-STROKE ENGINE SALE COMPARE & SAVE OSFS4O8950 OSFS6O12500 OS ES 7514500 OS ES 1 20T34900 ENYA4O-4C 50 ENYA6O-4C- -14950 ENYA9O-4C 950 SAITO 308450 SAITO 40-Il9950 SAITO4510950 SAITO 90T29950 TERMS Prepald check money order Include $250 UPS avid street address Calif residents add 6% sales tax No credit cards please Allow 2 weeks delivery REDWOOD hobby Imports PO BOX 6171 SANTA ROSA CALIF 95401 Sublect stock hand Designers Builders Fine PRE-BUILT RIC Models Fire Fox Pre-Built Price $12495 Engine Size 40 cu Wing Span 521A Radio 4 Channels balsa construction Ready fine sand covpr Control surfaces hinged Has bolt-on wing HalIco landing gear ABS wheel pants mounted axels stalled Fitted canopy Instruction booklet hardware included ERO 3850 US Hwy 19 No Palm Harbor FL 33463 ECH RIC813 938-3266 Dealer Inquiries Invited Oroer Today Send check MO also accept Master Card Visa Models shipped 350 PSI carton via UPS Add $850 shipping han dling Florida residents add 5% sales tax diameter varied results shown Table 5 Tables 4 5 can easily see variations prop size can significantly affect motor power examples applied voltage held constant current increased prop size thus power increased illustrates rather graphic fashion relationship power input up point power out put increasing prop size power increase has associated dual con sequences rapid battery discharge high enough currents some risk motor brushes 5 For constant applied voltage slower motor turns higher current drain also evident Tables 4 5 Thus fast-moving plane effective propeller rpm creases due prop unloading cur rent demand drops Translation longer run ning time Conversely small prop turning high revs large slow-moving glidertype approaching static test conditions relatively higher current inefficient power utilization because prop slip ping example larger slowerturning prop speed reducer will make much better use available energy stored battery case current demand always drops flight its question much later test conditions used demon strations herein considered within reasonable range operating capability motors used except * values cases data taken very quickly higher current levels either known damaging sure did want find out other hand some data points power levels too low useful flight Nevertheless representations believed fair Again its relative performance parame ters absolute accuracy mat ters 6 The power input required motors turn given prop same rpm nearly same may surprising performance factor vividly shown accompanying graph compares power input 11 samples nine different motor types turning same 6 x 4 propeller same propeller eight 11 motors performed within ranges shown Table 6 Three motors considered removed enough trend excluded table removed inefficient power input watts 51 10000 rpm 70 11000 101 12000 information evident part propeller determines input power given rpm part motors used comparable efficiencyat least over reasonable op erating power range de signed last statement means power lost motor process doing its intended job about same motors lost power mostly form heatmore later Its interesting note the least efficient motors tested among costly middle-of-the-road occupied comparatively low-cost sleevebearing types some exceptions course efficient motors consume least power spinning given prop will run longest par ticular battery Names motors tests will supplied unless inquiier manufacturers involved 40 wing 15 25 Engines Dealers & Distributors Welcomed Phone 703 273-9593 FLYLINE MODELS INC PO Box 2136 Fairfax Virginia 22031 USA November 1983 171 magic Dragon Trainer Pre-Bui Price $9995 Engine Size 25 CU Wing Span 55 Radio 3 4 Channels balsa construction Ready fine sand cover Control surfaces hinged HalIco landing gear 5132 nose gear strut Fitted canopy Instruction booklet hardware included Five Other Models Available Send Now Free Brochure ctru~ Pre-BuIlt lrice $10995 Engine Size 40 Wing Span 52 Wing Area 614 sq Length 385/8 Weight 4 lbs Radio 4 Channels IN STOCK FOR IMMEDIATE SHIPMENT New 30 CID QUADRA $20950 New 22 CiD QUADRA $10950 Reg 22 QUADRA $10400 Brisighelia Fiywheei $12400 Rag 22 QUADRA POWER ASSEMBLY ONLY$0400 QUADRA REPAIR 000 pius parts Jim Messer ERCOUPEPLANS $2395 KIT $23995 Jim Messer TOMAHAWKPLANS $2395 KIT $25gg5 Jim Messer9BALLTRAINER PLANS 41895 KIT gggg BALSA BASSWOOD 1811 ajuesl 35% OFF Concept FLEET PLANS $2995 KIT 515995 COWL $1995 FLOATS 35115 scale core $1795 complete kit $3996 FLOATS 4W scalecores $2195 complete kit $4795 CECONiTE Product 10) OFF Sig J3 CUB KIT $12495 PLANS SUPER STEARMAN Godfrey $2895 STARDUSTER TOO h Brisighelia J-2 CUB Neiitz $2995 VOLKSPLANE Chicken Charlie $2395 COCKPIT KITS Tomahawk F4U1 Spitfire $2398 Ercoupe $2095 Stearman $2295 Citabria $2495 J3 Cub $2195 ME-lOg $2295 Fleet $2195 US Quadra FUEL TANKS16 ou $695 32 oz 5795 FIBERGLASS ARROW SHAFTS 5/10 s 32 long 0/$1000 24-Hour Service . Add $250 postage Send Bank Check Money Order JIM MESSERS QUALITY MODEL PRODUCTS 106 Valley View Dr Aliegany NY 14706 R/C Capitol offers worlds finest RC custom built-up RC scale aircraft Quarter Scala PlansEa 92495PP Quarter Scale Pertial KitsEn $95OOPP Quarter Scale Custom-Built DeluxEa $500OOPP Piper Pacer PA-20 89 Wingspan Piper Tn-Pacer PA-22 89 Wingspan DH-85 Leopard Moth 111 Wingspan DH80A Puss Moth 111 Wingspan Please send $100 self-addressed stamped envelope complete list HOBBY CAPITOL RIC ESt 1951 46 N Oak St Ventura CA 93001 805643-7616 e 642-8465 Distributors Finest Quality Built-Up A/C Aircraft Custome Built Ready-ToFly Radio Controlled Modal Airplanes Classic R/C Scale SGRAT LAK TII LT-50 Electric Motor 01 Cu Ifl equivelent gas engine displacement Send self-addressed stamped envelope catalog ap plication notes Leisure 11 Deerspringllrvine/CA 92714 readers think Im hung up small motors props allow pro vide some information bigger stuff Table 7 data limited admittedliy represents some unlikely unde sirable combinations point about props determining motor input power fur ther illustrated comparison Table 7 really stands out deserves further comment Im refer ring Astro 25 Astro 075 speed reducer both turning 9 00 rpm Remarkable isnt Whats catch None some considerations 25 operating well below its nor mal intended power level twice power level shown might say 25 being underutilized example other hand 075 system being very well used Its lighter weight lower cost could reasonably pushed mOch higher normal power capability 25 Whatever prop dictating power demand point Im making get Part 4 batteries youll see energy tanks must con sidered part big picturethe total Electric system picturewhere choice system component sort team choice Translation want run 9 x 6 8000 other motor/prop/rpm combination fly some plane some specific duration battery because practicalities cell size number cells charging considerations 2 Motor propeller plane efficiency data examples given part have nominal operating condi tions motor propeller mean operating conditions would representative good fly ing power levels Putting yet another way would conditions reasonably good efficiency motors props presented used suitable plane Efficiency power output divided power input always number less meaning get less out put difference wasted power mentioned earlier Another point made earlier electrical power put motor easily measured simply product motor input volt age wattage current Power outputrelated work done motor its propeller moving both air planeis easily measured Anyway efficiency curve has shape bit like hook clothes hanger maybe like climb level-off dive roller coaster means some power range maximizing efficiencythe place percentage power lost least information Ive seen peak actually rounded usually represents rather broad range good power utilization 172 Model Aviation motor/prop maY primary con sideration Power Soar New Heights other words dont have oper ating exactly very peak impossible maintain anyway enjoy lot great flying Far either side broad max imum region however operating ex tremes efficiency can terrible flight will also terrible what extremes low ends efficiency curve can come end low power levels ratio output power input power small because example much input power goes kinds losses shown Table Ithe no prop power used overcome friction etc Thus small amount power de livered prop may comparable less lost would almost al ways no-flight condition anyway saw power region very low wattage region indeed other end efficiency curve very high input power levels motor losses rise very rapidly due example heating area operation cur rent input very high such too much voltage applied too large prop used power lost heat rises rapidly because power product current times current times resistance commonly called squared R' losses resistance armature windings brush-tocommutator contact resistance brush material brush connection resistance big driver current times itself Thus under such conditions more current input lower lower percentage power output ef ficiency curve drops off sooner later motor may go belly up excess ive brush heat heating concern Ive alluded often comes few words motors currently use simply adaptations some readily available often imported standard low cost unit intended con sumer applications nothing wrong this allows variety low cost what can see appli cation model use probably tasks motors far other intended ap plication application feel putting motors past limits design intent experience first mani festation brush damage very high currents Anyway more motors becoming available have much better behavior regard other things parts continuing Elec tric evolution Later get planes stallations well look some actual exam ples operation some guidelines help assure longevity investment along lots enjoyable flying fun now should clear motor prop independent plane What can too much motor bench static may case air providing plane moves out quickly allowing prop unload As mentioned earlier motor turning small November 1983 173 prop fast slowly-moving glider-type inefficient potentially bad-for-themotor situation Now let describe ex ample thats similar other direc tion Ive twice occasion help someone ARF Kraft Shoestring tractive planes 05-sized motor six cells 06 Ah size nylon props 8 x 6 planes just sorta mushed along studying situation respect weight area etc seemed really should fly better changed prop nylon 7 x 6 did trick motor turned up faster expected drew less current motor-prop-plane combination now much better fact plane much fun fly Simple huh does know what may have realized clue solution came three paragraphs earlierlook back see Admittedly above discussions simplifications incomplete theres involved motor/prop/plane performance discussed far think weve gone far enough get general ideathat theres variety motors avail able work quite well prop choice power closely related good results efficient motor/plane/prop combination thats needed Well al subject must covered before can look what works well together WS 54 29 35 ENGINtS 3 CHANNEL THE BEGINNERS KITTEN AND EXPERTS TIGER Revolutionary snap-on wing eliminates bolts rnbber bands complete kit $54 95 dealer direct GEMINI MODELS INC PO Bn 1168 Pasc NJ 07055 topic comes up next month Batteries Remember promised two things basics things work intend keep commitment So far weve dealing mostly first part promise will seriously pursue Elec trics basics given will sooner later directly contribute success own Electric design choices part making guy mentioned Part 2 guy understands basics knows what to worksthe guy whos 'got together Electrics closing note first four parts series will have written before Part 1 reaches readers expect installment will raise questions Despite good inten tions know some things will overlooked some things will unclear can welcome critic regard Perhaps most-asked questions can collected answers presented read wrap-up installment meantime will endeavor responsive individuals expediently possible Please direct questions SASE author Bob Kopski 25 West End Dr Lansdale PA 19446 SAFE FLYING IS NO ACCIDENT SAM Champs/Mathews Continued page 81 really means something SAM types host chapter SAM No Contest Director Jim Thomas obviously done homework example fact no sooner mentioned nice would someone water down dusty access road water truck arrived did just process repeated two three times daily Although no hookups available campers motor homes contest site sev eral self-contained vehicles well tenters campers stayed ovemight site Motel ar rangements well-handled Tanya Baird Chamber Commerce office available room LaJunta reserved mid-April attendees found accommodations nearby towns Rates very reasonable Ad ditional rooms available Otero Junior Col lege stayed reported clean air-conditioned facilities lots bull ses sions progress times lounge area concessionaire provided food drink flying fieldagain very reasonable prices However breakfast Laiunta proved bit hassle sudden influx hungry modelers demanding breakfast 600 am overtaxed staffs local restaurants making rather slow service fact some eateries didnt open until 700 am seems real crux problem contest manage ments decision start flying 800 rather originally-announced time 900 am scheduling change made order get competition over hour earlierto get out heat As matter fact since LaJunta far eastern edge Mountain timezone flying could have scheduled start 600 am contest day could have ended early 300 pm Go Upty Up-Up Problems effect high altitude engine power glide models didnt seem severe anticipated Although power-loss certainly factor major problems seemed i/A reed-valve engines Texaco event Climbouts certainly lower slower peculiar distribution lift atmosphere real oddity saw As repeatedly observed lift existed strata model would riding rather large boomer another plane immediately below above would downer Ther mal pattems much like seen Lake Charles LA accustomed finding Great Plains 174 Model Aviation product can recommendSUPER HAND SAN DER Dealers & Distributors Wanted confidenceHOBBIESTSee Hobby Dealer Call Art Gross Enterprises HOBBY DEALERCa// Distributor 06/743-9332 ART GROSS ENTERPRISES 12516 MAPLEWOOD AVE EDMONDS WA 98020 DUAL PERSONAUTY TRAINER GEENIS BEAUTIFULI SUPER CHAMP [F6T\F1 Invited Liti IjI.u Inc Dealer inquiries High pert onnante model engine connecting rods connecting rods made tha beat materials available designed give long service eliminate rod breakage modern high-Peef mance model engines Used leading aircraft boat car racers hobbyists Rods available popular model engines Look RPM new innovative products wish proven performance records Richardson Precision Machining Inc 5070 Golden Dr San Jose cA 5612914061 2S7-7068
Edition: Model Aviation - 1983/11
Page Numbers: 93, 94, 95, 170, 171, 172, 173, 174
This authors testing setup evaluation motors props results shown tables discussed text power supply fully adjustable zero 30 volts up 20 amperes two digital readouts motor voltage current analog meter tachometer optical pickup remotely located under motor mount Light source also remotely located Photos author THE FIRST INSTALLMENT series September issue described some pros cons electric-powered models last month covered motors use Some basic aspects motors de scribed practical considerations covered Earlier asked have faith read daringly onward remind because realize subject part may appear both simple some strange others However think some up coming information will surprising interesting manyand perhaps little confusing ditficult others first reading still others some what fol lows may downright boring seem totally irrelevant taken alone section however combined ether parts series will provide very intimate overall feel exactly what \Ki O iOE ra popellor rave electricpowered models yoi re new Electrics authors test results may astound second reading may required fully grasp some points thai made that1s what takes suggest Part 3 November 1983 93 goes motor battery pro peller given planeand affect flight results get other words series continues will come together' encourage un daunted continuance series Im sure will find worthwhile presentation seems too slow 80 70 60 -50 40 -8 tedious remern ber introduction Electricson installment plan Its necessarily easy installment plan either read write Hox ever maintain subject can generally simple oc t V 0 0 0 ----V e Lu 0 0 0 0 0 -I C V e 0 V C 0 0 RPM X 1000 91011 SC V0 certainly successful though neces sadly short Perhaps some readers have disap pointments Electrics just because some details made light glossed over elsewhere Thats Model Avi ation has planned seriesto make sure adequate introductory treatment such anyone wants can very successful Electric flier theres some useful stuff Gas guys honest well-intended series cannot complete detail-perfect several reasons dont know everything Another Im trying se lect meaningful useful offer ings consistent limitations pub lication space presentation time can fact best can can criticautomaticallyby asking questions 1 Propellers power Now Chave seen some Electric models Part have some introductory insight motors Part 2 could wondering what business concerning power heating performance about Lets look what happens motor required its thingturn prop power plane leading suppliers Electric flight systems provide instructions regarding choice model size weight suit able propellers things will also addressed another part series meantime get good feel motor operation propellers power lets look things static environment ie bench rather flight experience excellent correlation tween what observe bench what experience air A Power inputno prop Electrical power product electric potential volts electric current amps case motor input power motor terminal voltage times motor terminal input current amperage product V x power watts power comes frm energy 12131415 tank battery tank specific size can deliver its fill Part 4 will cover batteries detail discuss much tanks' can deliver Now however going get feel just Shown motor input power various motor speeds rpm 11 samples nine different motor types swinging Cox 6-4 gray prop Note different symbol 11 motors Connect like symbols form smooth performance curves through various speeds Note generally tight clusters data points throughout range test 94 Model Aviation Table 1 Typical Motor Power InputNo Prop MotorVoltsAmpsWatts Astro 0560075450 p/n 210770078546 80081648 90084756 Leisure LT-5050119595 Pattern Wind60124744 7013091 Mabuchi5011859 RS540S65276013078 70146102 80153122 Table 2 Performance Variation Various Same Size Props Propeller 64AmpsWatts Top Flite Nylon1168113300 Top Flite Wood13393112700 Cox Gray155*10912200 Table 3 Typical Motor/Propeller Performance Voltage Variation VoltsAmpsWattsRPM 60795488000 65905598550 70100709050 75110839600 801219710000 8513011110500 133 120 110 100 90 much fuel used motors next month youll have appreciation Part 4 As mentioned earlier motor running no prop draws small amount current sufficient overcome losses due friction other things illustrate sev eral examples shown Table measurements made using test setup pictured Notice something particular about data Table example motor current increase large crease voltage caused will case prop measurements tests made using convenient adjustable power supply exactly same re sults would occur motor bat tery interested power supply pictured capable up 30 volts 20 amps has remote voltage sense assure correct voltage motor terminals Also has adjustable current limit dont have accident during some zealous data run power capa bility may sound impressive believe expect need capability near future point want make special note has experience Ive told same Electric flight system suppliers performance production flight motors varies about plus-or-minus 10% As youll also see props also vary greatly load present motor battery course measurement motor performance has instrumentation accuracy associated Thus rea sons apparent differences Electric flight experience can occur Em noting now just case anyone reading has has read about different results B Power inputwith props ifl tables various motor performance mea surements different props ahown Whats mportant absoLve ac curacy relative performances -i particuiar notice bow rapidly input power changes tbattery voltage dra matic eFfect piop size can hae youll see important use right prop temptation just stick bigger prop add another cell may have carefully con sidered What seems like small change may fact either present unbearable load motor lest cause decline power system efficiency Remember static demonstrations motor/prop moving forward actual flying condi tions aircraft speed etc can have signifi cant influence data 1 All propellers same size necessarily created equal demonstrate ran Leisure LT-50 Pattern Wind very nicely-made motor three different 6 X 4 props applied voltage held constant 70 volts much like battery would hold nearly-constant voltage Table 2 lists resulting current drain input power rpm Notice wide variation power input roughly translates about same variation power output flight per formance might inclined say prop better prop remember dont get something nothing output performance input power means faster battery dis charge shorter flight timealthough increased flight performance may very well worth depending plane want fly some simi larity running engine full bore vs half throttle latter goes longer tank fuel Does Cox 6 x 4 gray fly aerobatic Jack Rabbit hotter Top Flight 6 x 4 nylon betcha buddy gives shorter flight too 2 A small change voltage makes big change performance demon strate propped Mabuchi Continued page 170 November 1983 95 Table 4 Effect Propeller Pitch Motor Input Power PropAmpsWattsRPM 8-468487950 8-580567550 8-696677000 8-8117826200 Table 5 Effect Prop Diameter Motor Input Power PropAmpsWattsRPM 6-437269000 7-450358400 8-469487900 Table 7 Some Larger Motor/Prop/Power Demonstrations MotorPropRPMPower Astro 259-6 wood700086 watts Astro 109-6 wood700090 watts Astro 075* *9-6 wood700080 watts Astro 259-6 wood8000126 watts Astro 075* *9-6 wood8000115 watts Astro 2512-6 wood5100115 watts Astrol5**12-6wood510096watts Now 1 ** means motors used matching speed reducers 2 In cases motor clearly over-propped operating conditions carefully controlled no risk motor involved 3 No voltages currents givenonly product power voltages currents generally well removed values would considered normal motor its normal prop Consider above academic exercises necessarily practical cases Table 6 Input Power Given 6-3 Prop Specific RPM RPM100001100012000 Watts44/360/S77 16 Close-up motor being tested Power motor supplied through cables connector extreme left Two test clip connections provide remote sensing precise control applied voltage Wood V-block underneath motor has rubber padding conjunction rubberbands stretched across top provide sturdy mount hold largest motors intended models NOW THERES QUICK AND EASY WAY OF ClEANING YOUR MODEL CRAFTS Super-K Model Cleaner Remaves fu Residue dirt contact1 CEJTS ClEANING TiME IN HALF Just spray model solvent wtpe soft cloth paper towel SIMPLE AS THAT Leaves craft showcase cleani eWoni hami Pahits Coverings Dries clew fast Eminates Ihe WOk cleaning model Strong Professonal Quality formula Great Model Craft Scots manes Helicopters Cleans Gently Protects delicate model DEALERS WANTED DOMESTIC & OVERSEAS WE EXPORT Hurry Have product shelves time Christmas guaranteed top seller Sugg retail $550 per gallon Contact us price structures ordering Information Also ask about other Super-K products Model Industry Ale Manufacturers & Major Brands DIstributors Model Engines Kits Radios & Accessories Super-K brand Kings RadIo Control Hobbles International 3960 West 16th Ave Hlaleah Florida 33012 Phone 305 557-2024 SS NEW * NEW * NEW BUY ECONO-PAC & SAVE WACO HKS-1GREAT LAKES TRAINER GREAT LAKES SPECIAL2T1A/2T1E PLAN$27OOppPLAN$27ttpp PG Cowl$27OOpp FG Cowl527OOpp F G Pants$25ttpp ECONO PAC$49OOpp ECOND-PACS70OOpp SAVE$600 SAVE $900 Parisian Moustique pian$17OOpp -. mixture reed valve todays ubiqui tous Cox 1/2As meetings interested modelers Brown delights producing engine pocket flash dis assembling spreading its parts out table before amazed onlookers Without too much prodding hell also demonstrate still operates just well day built Among pictures two fine examples 60 cu Brown Junior prototypes handbuilt Brown late 1931 early 1932 Both engine number A2 A5 share same basic characteristics though differ pther minor detail example like common production Browns later years engine A2 discharges its spent gases directly through tour D-shaped exhaust ports cut rear cylinder just above intake manifold engine A5 however exhaust ports concealed exhaust manifold two round threaded out lets Brown made least other engine manitolded like additional touch spark plug offset horizontally rear Incidentally both engines A2 A5 have steel pistons fitted curious ar rangement two cast iron piston rings dif ferent widthsan upper narrow com pression ring above lower very wide oil ring Note very short flared intake tubes sandcast crankcases handmade spark plugs common both early engines Max Bassetts Brown Junior number A17 manufactured Walter Hurleman Brown developed engines first pro duction tooling early summer 1932 different edge contour en gines bypass cover intake manifold indi cates parts die-stamped rather hand-formed engines A2 A5 intake tube also longer slightly larger diameter engine other 40 50 A-model Brown Juniors Hurleman said have produced before Bill Brown parted company late 1933 first have ringless precision-ground steel pistons remained hallmark qual ity model engines years afterward minor changes Hurleman continued manufacture limited quantities engine under own name until 1937 1938 Meanwhile Junior Motors Corporation organized early 1934 Bill Brown began oversee production yet another Brown Juniorthe 1934 model Bwhile still sophomore Penn State Financed Edward Roberts Philadelphia bankers son actually ran company Junior Motors turned out 50000 Brown engines before ceasing production eight years later Roberts served AMAs third president 1939 through 1942 hobbys earliest promoters Radio Control RS550S6530 good inexpensive hard-toget motor Top Flite 7 x 6 nylon Table 3 shows what happens input current input power rpm voltage varied test voltage range chosen might easily represent battery behavior just-off-charge through its useful Electrics/Kopski Continued page 95 run-down Notice dramatic power change Again static behavior shown table indication flight behavior Yes Electric noticeably hotter right after charge Ni-Cds characteristically drop initial high terminal voltage rapidly slowly decline through long plateau finally drop dramatically end-ofcharge Thats plane flies too Ive always feeling some suppliers ad vertise products performance right charge peak 3 For given propeller small change rpm representative significant change power/performance other key piece information evident Table 3 Dont treat few hundred rpm change disregard works Gas too seemingly small change tach ometer reading can indeed significant tachometer accuracy youre comparing results others Now well look implications changing prop size both diameter pitch 4 Variation prop size has signifi cant effect power performance demonstrate used favorite motors older version Astro 075 motor powered constant 70 volts propellers used Top Flite wood Labeled size assumed accurate First diameter held constant pitch varied results shown Table 4 pitch held constant 170 Model Aviation 4-STROKE ENGINE SALE COMPARE & SAVE OSFS4O8950 OSFS6O12500 OS ES 7514500 OS ES 1 20T34900 ENYA4O-4C 50 ENYA6O-4C- -14950 ENYA9O-4C 950 SAITO 308450 SAITO 40-Il9950 SAITO4510950 SAITO 90T29950 TERMS Prepald check money order Include $250 UPS avid street address Calif residents add 6% sales tax No credit cards please Allow 2 weeks delivery REDWOOD hobby Imports PO BOX 6171 SANTA ROSA CALIF 95401 Sublect stock hand Designers Builders Fine PRE-BUILT RIC Models Fire Fox Pre-Built Price $12495 Engine Size 40 cu Wing Span 521A Radio 4 Channels balsa construction Ready fine sand covpr Control surfaces hinged Has bolt-on wing HalIco landing gear ABS wheel pants mounted axels stalled Fitted canopy Instruction booklet hardware included ERO 3850 US Hwy 19 No Palm Harbor FL 33463 ECH RIC813 938-3266 Dealer Inquiries Invited Oroer Today Send check MO also accept Master Card Visa Models shipped 350 PSI carton via UPS Add $850 shipping han dling Florida residents add 5% sales tax diameter varied results shown Table 5 Tables 4 5 can easily see variations prop size can significantly affect motor power examples applied voltage held constant current increased prop size thus power increased illustrates rather graphic fashion relationship power input up point power out put increasing prop size power increase has associated dual con sequences rapid battery discharge high enough currents some risk motor brushes 5 For constant applied voltage slower motor turns higher current drain also evident Tables 4 5 Thus fast-moving plane effective propeller rpm creases due prop unloading cur rent demand drops Translation longer run ning time Conversely small prop turning high revs large slow-moving glidertype approaching static test conditions relatively higher current inefficient power utilization because prop slip ping example larger slowerturning prop speed reducer will make much better use available energy stored battery case current demand always drops flight its question much later test conditions used demon strations herein considered within reasonable range operating capability motors used except * values cases data taken very quickly higher current levels either known damaging sure did want find out other hand some data points power levels too low useful flight Nevertheless representations believed fair Again its relative performance parame ters absolute accuracy mat ters 6 The power input required motors turn given prop same rpm nearly same may surprising performance factor vividly shown accompanying graph compares power input 11 samples nine different motor types turning same 6 x 4 propeller same propeller eight 11 motors performed within ranges shown Table 6 Three motors considered removed enough trend excluded table removed inefficient power input watts 51 10000 rpm 70 11000 101 12000 information evident part propeller determines input power given rpm part motors used comparable efficiencyat least over reasonable op erating power range de signed last statement means power lost motor process doing its intended job about same motors lost power mostly form heatmore later Its interesting note the least efficient motors tested among costly middle-of-the-road occupied comparatively low-cost sleevebearing types some exceptions course efficient motors consume least power spinning given prop will run longest par ticular battery Names motors tests will supplied unless inquiier manufacturers involved 40 wing 15 25 Engines Dealers & Distributors Welcomed Phone 703 273-9593 FLYLINE MODELS INC PO Box 2136 Fairfax Virginia 22031 USA November 1983 171 magic Dragon Trainer Pre-Bui Price $9995 Engine Size 25 CU Wing Span 55 Radio 3 4 Channels balsa construction Ready fine sand cover Control surfaces hinged HalIco landing gear 5132 nose gear strut Fitted canopy Instruction booklet hardware included Five Other Models Available Send Now Free Brochure ctru~ Pre-BuIlt lrice $10995 Engine Size 40 Wing Span 52 Wing Area 614 sq Length 385/8 Weight 4 lbs Radio 4 Channels IN STOCK FOR IMMEDIATE SHIPMENT New 30 CID QUADRA $20950 New 22 CiD QUADRA $10950 Reg 22 QUADRA $10400 Brisighelia Fiywheei $12400 Rag 22 QUADRA POWER ASSEMBLY ONLY$0400 QUADRA REPAIR 000 pius parts Jim Messer ERCOUPEPLANS $2395 KIT $23995 Jim Messer TOMAHAWKPLANS $2395 KIT $25gg5 Jim Messer9BALLTRAINER PLANS 41895 KIT gggg BALSA BASSWOOD 1811 ajuesl 35% OFF Concept FLEET PLANS $2995 KIT 515995 COWL $1995 FLOATS 35115 scale core $1795 complete kit $3996 FLOATS 4W scalecores $2195 complete kit $4795 CECONiTE Product 10) OFF Sig J3 CUB KIT $12495 PLANS SUPER STEARMAN Godfrey $2895 STARDUSTER TOO h Brisighelia J-2 CUB Neiitz $2995 VOLKSPLANE Chicken Charlie $2395 COCKPIT KITS Tomahawk F4U1 Spitfire $2398 Ercoupe $2095 Stearman $2295 Citabria $2495 J3 Cub $2195 ME-lOg $2295 Fleet $2195 US Quadra FUEL TANKS16 ou $695 32 oz 5795 FIBERGLASS ARROW SHAFTS 5/10 s 32 long 0/$1000 24-Hour Service . Add $250 postage Send Bank Check Money Order JIM MESSERS QUALITY MODEL PRODUCTS 106 Valley View Dr Aliegany NY 14706 R/C Capitol offers worlds finest RC custom built-up RC scale aircraft Quarter Scala PlansEa 92495PP Quarter Scale Pertial KitsEn $95OOPP Quarter Scale Custom-Built DeluxEa $500OOPP Piper Pacer PA-20 89 Wingspan Piper Tn-Pacer PA-22 89 Wingspan DH-85 Leopard Moth 111 Wingspan DH80A Puss Moth 111 Wingspan Please send $100 self-addressed stamped envelope complete list HOBBY CAPITOL RIC ESt 1951 46 N Oak St Ventura CA 93001 805643-7616 e 642-8465 Distributors Finest Quality Built-Up A/C Aircraft Custome Built Ready-ToFly Radio Controlled Modal Airplanes Classic R/C Scale SGRAT LAK TII LT-50 Electric Motor 01 Cu Ifl equivelent gas engine displacement Send self-addressed stamped envelope catalog ap plication notes Leisure 11 Deerspringllrvine/CA 92714 readers think Im hung up small motors props allow pro vide some information bigger stuff Table 7 data limited admittedliy represents some unlikely unde sirable combinations point about props determining motor input power fur ther illustrated comparison Table 7 really stands out deserves further comment Im refer ring Astro 25 Astro 075 speed reducer both turning 9 00 rpm Remarkable isnt Whats catch None some considerations 25 operating well below its nor mal intended power level twice power level shown might say 25 being underutilized example other hand 075 system being very well used Its lighter weight lower cost could reasonably pushed mOch higher normal power capability 25 Whatever prop dictating power demand point Im making get Part 4 batteries youll see energy tanks must con sidered part big picturethe total Electric system picturewhere choice system component sort team choice Translation want run 9 x 6 8000 other motor/prop/rpm combination fly some plane some specific duration battery because practicalities cell size number cells charging considerations 2 Motor propeller plane efficiency data examples given part have nominal operating condi tions motor propeller mean operating conditions would representative good fly ing power levels Putting yet another way would conditions reasonably good efficiency motors props presented used suitable plane Efficiency power output divided power input always number less meaning get less out put difference wasted power mentioned earlier Another point made earlier electrical power put motor easily measured simply product motor input volt age wattage current Power outputrelated work done motor its propeller moving both air planeis easily measured Anyway efficiency curve has shape bit like hook clothes hanger maybe like climb level-off dive roller coaster means some power range maximizing efficiencythe place percentage power lost least information Ive seen peak actually rounded usually represents rather broad range good power utilization 172 Model Aviation motor/prop maY primary con sideration Power Soar New Heights other words dont have oper ating exactly very peak impossible maintain anyway enjoy lot great flying Far either side broad max imum region however operating ex tremes efficiency can terrible flight will also terrible what extremes low ends efficiency curve can come end low power levels ratio output power input power small because example much input power goes kinds losses shown Table Ithe no prop power used overcome friction etc Thus small amount power de livered prop may comparable less lost would almost al ways no-flight condition anyway saw power region very low wattage region indeed other end efficiency curve very high input power levels motor losses rise very rapidly due example heating area operation cur rent input very high such too much voltage applied too large prop used power lost heat rises rapidly because power product current times current times resistance commonly called squared R' losses resistance armature windings brush-tocommutator contact resistance brush material brush connection resistance big driver current times itself Thus under such conditions more current input lower lower percentage power output ef ficiency curve drops off sooner later motor may go belly up excess ive brush heat heating concern Ive alluded often comes few words motors currently use simply adaptations some readily available often imported standard low cost unit intended con sumer applications nothing wrong this allows variety low cost what can see appli cation model use probably tasks motors far other intended ap plication application feel putting motors past limits design intent experience first mani festation brush damage very high currents Anyway more motors becoming available have much better behavior regard other things parts continuing Elec tric evolution Later get planes stallations well look some actual exam ples operation some guidelines help assure longevity investment along lots enjoyable flying fun now should clear motor prop independent plane What can too much motor bench static may case air providing plane moves out quickly allowing prop unload As mentioned earlier motor turning small November 1983 173 prop fast slowly-moving glider-type inefficient potentially bad-for-themotor situation Now let describe ex ample thats similar other direc tion Ive twice occasion help someone ARF Kraft Shoestring tractive planes 05-sized motor six cells 06 Ah size nylon props 8 x 6 planes just sorta mushed along studying situation respect weight area etc seemed really should fly better changed prop nylon 7 x 6 did trick motor turned up faster expected drew less current motor-prop-plane combination now much better fact plane much fun fly Simple huh does know what may have realized clue solution came three paragraphs earlierlook back see Admittedly above discussions simplifications incomplete theres involved motor/prop/plane performance discussed far think weve gone far enough get general ideathat theres variety motors avail able work quite well prop choice power closely related good results efficient motor/plane/prop combination thats needed Well al subject must covered before can look what works well together WS 54 29 35 ENGINtS 3 CHANNEL THE BEGINNERS KITTEN AND EXPERTS TIGER Revolutionary snap-on wing eliminates bolts rnbber bands complete kit $54 95 dealer direct GEMINI MODELS INC PO Bn 1168 Pasc NJ 07055 topic comes up next month Batteries Remember promised two things basics things work intend keep commitment So far weve dealing mostly first part promise will seriously pursue Elec trics basics given will sooner later directly contribute success own Electric design choices part making guy mentioned Part 2 guy understands basics knows what to worksthe guy whos 'got together Electrics closing note first four parts series will have written before Part 1 reaches readers expect installment will raise questions Despite good inten tions know some things will overlooked some things will unclear can welcome critic regard Perhaps most-asked questions can collected answers presented read wrap-up installment meantime will endeavor responsive individuals expediently possible Please direct questions SASE author Bob Kopski 25 West End Dr Lansdale PA 19446 SAFE FLYING IS NO ACCIDENT SAM Champs/Mathews Continued page 81 really means something SAM types host chapter SAM No Contest Director Jim Thomas obviously done homework example fact no sooner mentioned nice would someone water down dusty access road water truck arrived did just process repeated two three times daily Although no hookups available campers motor homes contest site sev eral self-contained vehicles well tenters campers stayed ovemight site Motel ar rangements well-handled Tanya Baird Chamber Commerce office available room LaJunta reserved mid-April attendees found accommodations nearby towns Rates very reasonable Ad ditional rooms available Otero Junior Col lege stayed reported clean air-conditioned facilities lots bull ses sions progress times lounge area concessionaire provided food drink flying fieldagain very reasonable prices However breakfast Laiunta proved bit hassle sudden influx hungry modelers demanding breakfast 600 am overtaxed staffs local restaurants making rather slow service fact some eateries didnt open until 700 am seems real crux problem contest manage ments decision start flying 800 rather originally-announced time 900 am scheduling change made order get competition over hour earlierto get out heat As matter fact since LaJunta far eastern edge Mountain timezone flying could have scheduled start 600 am contest day could have ended early 300 pm Go Upty Up-Up Problems effect high altitude engine power glide models didnt seem severe anticipated Although power-loss certainly factor major problems seemed i/A reed-valve engines Texaco event Climbouts certainly lower slower peculiar distribution lift atmosphere real oddity saw As repeatedly observed lift existed strata model would riding rather large boomer another plane immediately below above would downer Ther mal pattems much like seen Lake Charles LA accustomed finding Great Plains 174 Model Aviation product can recommendSUPER HAND SAN DER Dealers & Distributors Wanted confidenceHOBBIESTSee Hobby Dealer Call Art Gross Enterprises HOBBY DEALERCa// Distributor 06/743-9332 ART GROSS ENTERPRISES 12516 MAPLEWOOD AVE EDMONDS WA 98020 DUAL PERSONAUTY TRAINER GEENIS BEAUTIFULI SUPER CHAMP [F6T\F1 Invited Liti IjI.u Inc Dealer inquiries High pert onnante model engine connecting rods connecting rods made tha beat materials available designed give long service eliminate rod breakage modern high-Peef mance model engines Used leading aircraft boat car racers hobbyists Rods available popular model engines Look RPM new innovative products wish proven performance records Richardson Precision Machining Inc 5070 Golden Dr San Jose cA 5612914061 2S7-7068