Dihedral

NO OCR TEXT NO OCR TEXT plane circles tighter banks up air speed increases Increased bank angle re duces span airplane relative circle axis thus reducing rolling-in mo ment increased speed also affects other things however analysis limited bank angles less about 300 fair approximation say no effects due bank angles effect high bank angles may seen tailing-off lines envelope Figure 3 bank angle effect lines would simply overlap Assuming bank angle limitation con sider variables independently wing area wingspan weight lift coefficient air speed yaw angle Equivalent Dihedral An gle circle radius bank angle con sider independently means vary variable time holding other var iables constant changing variable normally affects some oth ers turns out rolling-in moment due circling affected wing span weight circle radius mo ment proportional wing span2 weight l/circle radius fading fast hang get some meaty stuff shortly Reviewing quickly Part Two series rolling-out moment due yaw proportional wingspan wing area air speed2 yaw angle EDA compare sensitivity van ables rolling-in moment rolling-out moment can deduce fol lowing Yaw angle function bank gle steady-state circle proportional 1/wing area wingspan weight lIair speed2 l/EDA l/circle radius relationships will allow esti mate yaw airplane based charts explained below Examples will follow yaw angle plots Figures 3 4 show yaw angle required hold plane steady-state circle Figure 3 plots yaw angle function circle radius Figure 4 plots yaw angle function bank gle plots take account much complexity problem including effect bank angle increased speed bank angle effect ignored however en tire airplane has same sink rate wing has variable airspeed means inboard wing sees higher angle tack related inverse glide ra tio calculation typical Glider showed effect minor also complicates analysis immensely effect ignored plots show yaw single air plane flown variety weights speeds constant lift coefficient has 100 span 1000 sq area l0 EDA weights ranging about two seven pounds values especially lighter three airplanes typical sport RC Sailplanes Looking Figure 4 20 ftIsec 104 Model Aviation ADove rn-low curvajure maae VISIDICI As plane circles airatream passes over out board wing faster inboard wing tends make plane roll same time though vertical stabilizer tends align itself local flow means wing yaws outboard tends make plane roll out get variables right plane will circle stable fashion Below Low-dihedral aileron sailpianes have problem achieving spiral stability vertical stabilizer yaws airplane outboard insufficient dihedral produce net rollout moment especially true large lightweight aileron ships such 1 20-in-span Tango As resuit pilot must circle actively controlling rolling-in tendency top aileron Also tendency pilot increase circling airspeed well beyond optimum Improve spiral stability 03 025 02 LIFT Ib/005 span 015 01 005 -1 -08 -06 -04 -02 0 02 04 06 08 1 V-Dihedral - - APYal -Parabolic ML CL right tip WING STATION fraction semispan 0 -08 -06 -04 -02 0 02 left tipCL Figure 2 0406 08 right tip WING STATION fraction semispan Figure 1 Circling yawing shifts lift distribution outboard rolls plane inboard heavy line plotted represents lift distribution elliptical planform wing circling 30 bank angle fine line beneath lift distribution same wing level flight Extra lift due banking reflected greater average lift heavy line particular plot represents unyawed 100-Inspan 3-lb airplane 30 bank left circle Its level flight speed 20 ft/sec its speed bit higher create extra lift re quired bank angle Figure 2 Yawing outboard redistributes lift distribution Inboard balancing rolling-in moment Note lift distribution parabolic dihedral wing thin line almost symmetrical whereas V dihedral wing heavy line really loads up inboard left wing unloading left tip plot represents same airplane Figure 1 except now yawed outboard 870 model see has yaw some nine degrees circling 300 bank serious yaw Full-size airplanes use sideslip yaw dive brake us ing thermaling Now look what hap pens plane extreme floater fly ing 15 ftIsee 3O bank has yaw nearly 170 Talk about extra drag Calculating yaw angle Suppose have airplane has wing area in2 span weight b airspeed t/sec EDA ight typical FAT F3B-class Sailplane much would yaw com pared 30 ft/sec aircraft Figure 4 First ratio variables area /1000 span 100 weight 438 airspeed 0 EDA must also ratio circle radius proportional airspeed2 circle radius 2 above discussion know yaw must proportional 1/area span weight 1/airspeed2 1/EDA 1/cir cle radius Chaining variable ratios gether relative yaw must 1/110 x 120 x 0874 x 1/09332 x 1/050 x 1/0870 Going Figure 4 find 30 ft/sec airplane must yaw about 43 de grees new plane must yaw 252 x 43 degrees means typi cal F3B Sailplane must yaw outboard about 11 degrees circling 30-degree bank ailerons used hold up wing Since F3B Sailplanes have 30 dihedral clear effi cient thermaling top aileron must used actively pilot hold up inboard wing What have A-2 Nordic Glider cir cling 50-foot radiushow much must yaw Typical vital statistics wing area in2 span eight b airspeed t/sec EDA om pared 15 ft/sec airplane Figure 3 variable ratios would area 475/1000 span 00 weight 859 airspeed 5 EDA compute relative yaw ratios proportioned multiplied together Rela tive yaw 75 x 080 x 0484 x 1/09332 x 1/070 Figure 3 20 175 15 125 Yaw Angle 10 degrees 75 5 25 0 VolSft/sectJI VLI[i]iii J 175r j-.-I-J- 1 20 30 LU 175 15 II 125 Yaw Angie degrees 75 5 25 0 0 l0 203040 50 60 70 80 go 100 Figure 3Circle Radius feetFigure 4 Figure 3 Slower airplanes must yaw outboard lot plot shows yaw angle required circle steadily single airplane flown constant lift coefficient 10 variety weights Note yaw angle plotted against circle radius required yaw indepen dent weight until moderate bank angles reached example wingspan 100 wing area 1000 sq Equivalent Dihedral Angle 10g Vo speed airplane straight flight bank angle increases airspeed increases well weights different speeds slowest fastest 1659 lb 2531 lb 3306 lb 5165 lb 7438 lb Figure 4 As function bank angle slower airplanes must yaw much faster airplanes plot same airplanes shown Figure 3 except yaw angles plotted against bank angle instead circle radius Note maximum yaw angle reached bank angle 450 Beyond 450 wing becomes vertical difference airspeed over entire span diminishes very rapidly point Vo 5 75 20 25 30 6O 55 50 45 40 35 30 25 20 15 10 Dank Angle degrees October 1988 105 025 02 015 LIFT 1b/005 span 01 005 0 left tip Figure 1 find baseline 15 ft/sec airplane yaws about 600 circle radius 50 ft Nordic Glider must yaw 134 x 60 8030 Some Nordics use device creases angle attack inboard wing after tow release order hold up inboard wing much would wing above model have ro tated order eliminate required yaw Part series can calculate 8030 yaw wing 70 EDA gives 0980 change angle tack both wings achieve change wing must piv ot twice much about 200 General examples Now may clear can get yaw information baseline aircraft useful informa tion airplane Rather go through process plane range planes might consider ing following relationships may some use Again based sumption bank angle less 300 have same plane same lift coefficient different weights taken function circle radius yaw angle constant illustrated Figure 3 have same plane same lift coefficient different weights taken function bank angle yaw angle proportional 1/weight illustrated Figure 4 airplane proportionally scaled keeping wing loading same yaw angle function bank angle propor tional scale factor wing area weight kept con stant wingspan varied yaw gle function bank angle propor tional span span wing loading kept constant wing area varied yaw angle function bank angle con stant aspect ratio has no effect yaw angle span wing loading unchanged airplane kept same Equivalent Dihedral Angle varied yaw angle proportional 1/EDA span weight airspeed con stant wing area varied choosing between low high camber wing say yaw angle function bank angle proportional l/wing area High lift high aspect ratio wings yaw low camber low aspect ratio wings exact same airplane flown dif ferent airspeeds lift coefficients taken function circle radius yaw angle varies 1/airspeed2 Speeding up airplane really reduces amount yaw required exact same airplane flown dif ferent airspeed lift coefficient taken function bank angle yaw gle varies 1/airspeed4 As function bank angle yaw angle super sensitive airspeed Dihedral types three prototypical dihe dral types described briefly above de tail Part Two display some important dif ferences behavior circling Simply put V-dihedral wings have less tendency tip-stall polyhedral parabolic wings can flown lower speeds thermaling As planes circle planes yaw out board V-dihedral wing has same angle attack everywhere wing higher inboard wing less out board wing polyhedral wing has highest angle attack inboard tip progressing lowest outboard tip parabolically curved wing has smooth gradation angle attackhighest inboard tip lowest outboard tip Since dihedral angle tip panel polyhedral wing greater V dihedral wings dihedral angle inboard polyhedral tip panel greater angle attack inboard tip parabolic wing greater angle attack poses problem circling Nor mally models thennal near maximum lift coefficient close stall part wing gle attack will stall first limits minimum thermaling speed plane angle attack polyhedral wing greatest inboard tip panel panel limits maximum average lift coef ficient plane circling Like wise very tip parabolic wing lini its its average lift coefficient V dihedral wing limited entire board wing Since spread between maximum angle attack average angle attack least V-dihedral wings able fly slowest circling Parabolic wings have spread must circle fastest avoid stalling inboard tip advantage minor typical middle-weight mid-size RC Sailplanes Let us take example 20 ft/sec air plane Figure 4 300 bank angle also typical must yaw 960 informa tion presented Part can calculate V-dihedral inboard wing must have angle attack 1680 higher av erage angle attack polyhedral wing has tip panels 130 dihedral its inboard tip panel must have angle attack 220 higher average parabolic wing has its tips about 160 dihedral its inboard tip has angle attack about 270 higher average Continued page 175 r5 11 IIIII iilLj II IA J 5101520 Equivalent Dihedral Angle degrees 20 15 Yaw Angle 10 degrees S 0 IIIIII i1II1 III 0255075100125150175 Span inches 200 2530 Figure 6 FIgure 5 Yaw angle circle Inversely proportIonal Equivalent Dihedral Angle plot shows required yaw angle 20 ttIsec airplane used FIgures 3 4 bank angle 300 Major improvements can yaw angle Increasing dihedral say 5 10g less gain increasing tram say 20 250 Figure 6 nature bigger airplanes must yaw order remain stable theyre circling plot shows required yaw angle function wingspan 20 ft/sec airplane 100 Equivalent Dihedral Angle banked up 300 flying lift coefficient 10 Note required yaw angle proportional models wingspan 106 Model Aviation 20 18 16 14 12 Yaw Angle 10 degrees 8 6 4 2 0 Figure 5 Finally heartfelt salute order beautiful people gave selves make 1988 FAC possible successful addition Maxecuter ganizers special thanks Lin Juanita Reichel Tom Schmitt Bob Clemens Ma rie Rees Connie McSulskis Marian Mann Kathy Thomas Peg Paisley Shirley Kuenz Rich Hensel Pat Jupiter Gerry Helen Paisley Otto Kuhni Claude Powell Paul Spreiregen Western NY FF Society Geneseo National Warplane Museum Peck-Polymers Golden Age Reproduc tions Sea Glen Models Blue Swallow Mod els Flyline Models Flying Scale Inc well unsung volunteer timers go-fers helpers especially en thusiastic thanks superb contes tants willingly shared yourselves keep Free Flight Scale alive well growing Bladder/Weinreich Continued page 99 lines shorter reaction time re quired about same bigger contest models Phil Granderson Portland OR came fourth year has won contest twice before practiced playing video games air hockey also flew plane night training himself con trol model depending sight helps him concentrate opposi tion match Just important practice con struction models proper modifica tion engines wings con structed Styrofoam reinforced bal sa carbon fiber fiberglass strapping tape Stabs built lightness tail booms either built-up ones made carbon fiber arrow shafts Models have wingspans about 4 ft weigh 18 20 oz About half weight accounted engine engine mounts Like other Bladder Grabber partici pants Kott designs own planes re works engines putting brass cylinder liners aluminum pistons modi1ing crankshafts Most engines contest started out life Fox 35s Combat has come long way past 20 years Bob Carver remarked Com paring Combat plane 20 years ago today like comparing Model T new Porsche Carver has fly ing 25 years explained speeds have gone 80 120 mph engine power has risen one-half horsepower two Aerodynamics have changed airfoil shapes different moments better planes can turn tighter accelerate faster performance has improved reminded us has skill level pi lots' Ironically last years Nats winner Mark Smith Ft Worth TX found hes im proved models too much built new planes year quicker faster old ones used did fly well Smith rue fully explained Though didnt place years Bladder Grabber hes no quitter planning return next years Theres something about Combat flying just gets blood Bob Carver continues compete de spite never having won Bladder Grabber although year placed respectable seventh summed up way Its ultimate video game Its flier against another its strategy maneu vering evasion attack Its things actual fighter pilots have Ill give Bob last word too know youve alive says after youve flown Combat match As motto Combat observation would hard improve upon Dihedral/Beron-Rawdon Continued page 106 half-degree penalty polyhedral wing relative V-dihedral wing will force increase speed about 3% degree penalty parabolic wing rel ative V-wing will force 55% increase speed Because dihedral angle yaw angle reciprocal works out changing Equlvalent Dihedral Angle has no effect variations angle attack larger slower planes penalty severe Take 120-in-span 1000in2 25-lb plane thermals 175 ft/sec instance plane must yaw 150 300 bank angle V-dihedral plane will thermal 4% slower poly hedral plane 8% slower para bolic wing addition penalty imposed poly hedral parabolic wings steady-state circle another penalty imposed maneu vering circling particular initiat ing roll-out steady-state circle further loads up inboard panel tip loads up polyhedral parabolic wings order leave equal maneuvering margin top existing stall margin polyhedral parabolic wings must flown faster yet V-dihedral wing conclusion draw V-dihedral wings superior ther maling maneuvering thermaling contrast conclusion par abolic polyhedral wings superior steady-state rolling maneuvers mar gin superiority both cases very great important large slow airplanes Spiral stability Spiral stability refers ability airplane roll out cir cle rudder neutralized hold constant circle radius rud der held deflected plane very spirally stable will roll out circle quickly rudder centered will require substantial rudder deflection hold circle will fly straight still PRECISION MODEL PRODUCTS Made U S BARSTOCK ALUMINUM SPINNERS Pan NoSize fl-150B .. 1-1/2 TT-175B .. 1-314 TT-200-B TT-225-B .. 21/4 TT-226-B .. 2114 FAI 11-250-B .. 21/2 TT-251B . 21/2 FAI .. TI-275-B .. 23/4 TI276-B .. 23/4 FAt .. 11-300-B 11301-BFAIl 11325-B .. 3-1/4 l1-350B 3-1/2 11-375-B33/4. 11-400-B4 RetailApprox PriceWeight $1395058 02 149509502 1595100oz 169516002 189515002 189519002 2095170oz 229522002 249520002 269526002 289525002 3695340oz 4995470oz 599552002 6995570oz 3 Pieces Cone Back Plate Retainer Screw Note 3 4 Blade Spinners Available Sizes Add $300 Per Spinner PROP NUT ADAPTORS Pan No Size 11-140-A 28 11-147-A -28/7mm 11-610-A 10mm 11-710-A x 10mm 11-516-A 6-24 11-518-A . 5/16-24/8mm 11-810-A . Ox 10mm 11-825-AOx 125mm 11-375-A3/8-24 11-125-A10 x 125mm RetailApprox PriceWeight $495061 02 495 . 061 oz 495 . 063oz 495OB2oz 49507602 495 .076 02 495076oz 495075 02 595 .ll7oz 595 02 3 Pieces Nut Washer Machined Bushing Add $350 Shipping Handling Prices subject change notice ROMCO MFG INC OX 836 SOUTH HOUSTON TEXAS 77587 713 943-1867 October 1988 175 PlC Video Tape Vol 1 Basics 115 minutes total running time graat ducatLonal ualuc menckd clubs hobbj jJ$$YJkz\shop owners. Model AvIation Nov 1987 Only $1795 tax & shipping mci VISA M/C orders call 415 967-5134 Penn International Chemicals 943 Steirlin Rd Mt View CA 3 4 66 6666 666 6666666666666666666666666666666w 6 DUAL STRUT NICKEL PLATED NOSE GEAR iiiI I suIts Tooling P0 Box 95 ChampaIgn IL 61820 air indefinitely plane neutrally stable will remain circle con trols neutralized no rudder deflec tion required hold turn spi rally unstable airplane will circle tighter steeper controls neutral ized opposite rudder continudus ad justments required hold turn spirally unstable airplane will fly straight its ownit will gradually bank circle spiral down steepness tightness spiral determined degree spiral instability Free Flight models obviously must spirally stable ones arent will crash have limited experience Free Flights seems generous measure spiral stability would vir tue Nevertheless have seen successful models notably FM Power models appeared marginal respect have experience RC Sailplanes 1 am certain what exacfly best have flown spirally unstable air planes definitely unpleasant always try get away very difficult fly precisely other hand Sailplanes excess spiral stability require lot control input cir cle can give plane dull doggy feel may mask feel thermal present preference plane small-to-moderate amount spiral stability Once circle established such plane control input goes making adjustments seems easier sense thermal have seen circling airplane must yaw outboard certain amount avoid rolling spirally stable airplane will naturally yaw outboard amount two basic effects cause outboard yaw first due circular flight path plane second due variable airspeed over wing As plane circles its flight path streamlines curved Since vertical stabilizer aft wing sees dif ferent yaw angle wing vertical stabilizer approximately aligns itself flow airplane wing yaws out board effect illustrated pictures curvature flow can result remarkably large angles example imagine plane 25-ft-radius circle perimeter circle 157 ft distance between wing vertical stabi lizer three feet angle air flow between wing vertical stab approximately 3/157 x 3600 Thus absence other effects vertical stabilizer would align itself local flow airplane would yaw out board 690 Just un-yawed circling wing makes lift outboard panel also makes drag variation drag causes outboard yawing moment opposed lift vertical stabi lizer Lift vertical stabilizer gener ated yawing further outboard its neu tral zero lift angle principal variables spiral stability emerge natural yaw gle plane due its circular path de pends distance between wing vertical stabilizer circle ra dius yaw angle due variation wing drag depends degree varia tion drag turn depends circle radius wing section other fac tors size aspect ratio mo ment arm vertical stabilizer size moment arm vertical stabilizer characterized vertical tail volume quantified vertical tail area wing area x vertical tail moment arm wingspan aspect ratio vertical stabilizer also important since lift curve slope quite sensitive changes aspect ratio aspect ratio low Now see what makes plane yaw outboard other key piece Equiv alent Dihedral Angle Increasing dihe dral reduces amount plane must yaw avoid rolling achieve neutral spiral stability natural yaw angle plane assumes circling must equal angle required balance roll axis adjust spiral stability can either change angle plane natu rally yaws outboard can change angle plane must yaw avoid rolling BATT- CHEKBX Saves Time . 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also leave vertical tail mo ment arm three feet leave EDA 10 shrink vertical stab extra drag outboard wing can yaw plane outboard Exactly what size vertical stab must complex problem because large number variables number unknowns major var iable effect fuselage especially airplanes large long fuselages relative wing general models easier cut try accurately calculate some trade-offs can get spiral stability small vertical stab short moment arm can also get large small vertical stab long moment arm have too little vertical stab too little moment arm though airplane will have Dutch roll problems rhyth mic yaw-roll oscillation air plane looks pilot flying music waltz condition avoid Free Flight models often trimmed near condition however appears improve ability model center thermals itself perhaps because direction plane much affected what happening wing RC Safiplanes small verticals short moment arms will sluggish con trol because small vertical cannot gener ate much lift compound problem has little leverage plane addition such plane will poorly damped making precision flying difficult discussed Part series large vertical stab long moment arm will give RC models powerful control excellent damping disadvantage large surfaces have drag longer tail booms heavier Careful struc tural aerodynamic design can minimize disadvantages own preference toward larger verticals longer tail booms neat feature spiral stability works circle radii set up just stable 25-ft radius will still just stable 50-ft radius because amount plane must yaw pro portional 1/circle radius amount plane does yaw proportional 1/cirdc radius Keep mind depen dent variables some unpredictable dont expect perfection information see can estimate whether design will spi rally stable make effective adjustments have determine yaw gle required configuration de termine much yaw will occur effect flow curvature flow cur vature gives required yaw angle almost guaranteed have spiral stability need some out board yaw know vertical stab will have carefully sized best guess would typical RC Sailplanes can count plane yawing about two three degrees outboard very large vertical stabilizer would al low Some Free Flight Nordic models use very low aspect ratio verticals might allow something order six degrees guess remember Achieving spiral stability aileroncontrolled airplanes can problematic ample vertical stabilizer put reason able distance wing generous amount dihedral required achieve spiral stability turn causes tinwanted roll responses unintended yaw de flections such adverse yaw due aile rons crosswind takeoff perhaps gyroscopic coupling roll pitch axes Reducing size vertical stabi lizer may partially effective going too far can result very loose air plane Lengthening tail boom also helpful has its penalties weight drag An additional facet spiral stability pointed out Dr Andy Bauer described him paper National Free Flight Society Digest 1987 Note above required yaw angle circle given airplane very sensitive airspeed Faster airspeeds require substan tially less yaw angle means air plane may spirally stable low speeds may stable higher speeds Radio Control Free Right Gliders has great importance Free Flight mod els insufficient spiral stability cannot trimmed best glide elevator trimmed slow model optimum speed inadequate spiral stability model starts roll As does however gains speed improved spiral stability same time process begins circling higher less efficient speed model adequate spiral sta bility could have trimmed fly slower entering roll-in speedup cycle same effect occurs RC Sailplanes particularly ailerons low dihedral Such models unstable flying slowly auto matic tendency part pilot speed up thermaling thus degrading performance moral achieve maximum circling performance sure have adequate ample spiral stability effect also important considera tion RC power models especially trainexperience Great Performance Quartet DALOTEL 850 SPAN 69 InsWING AREA 830 sq ins CHIPMUNK 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No 454Sweet P30 FF Neat stick-and-tiune Outdoor Ruhher P-3D-class model contest-winner$296 No 457Spectra RU Eieclnc-power 05-san motor ama 3 dfifeunt wings oport asaring aembatics S700 No 4604-40 RU Sheelder-wing sport flier 4-cycle 43-size esgine 4 chaonels S696 No 465Blue Max II RU Fan-fly sportster 40-size enmo spans 52 Lightwieght stuctaw S700 No 475Buttercup RU Cute eRn sporfoter sees micu 2-ch RU puise-udder Spans 27 0201935 powerS300 No 490Weekender RU Low-wing sport fler 20-aloe 4-st uke eoglae opana 47 inS575 No 506Playmate RU Sport flier 3 RU channeis 16/25-olin engimo spans 50 inS650 No 512Extra 230 RU Olest Scale aceehatic plane spans 8 ft ama Onadra engine Two plan sheetsS1650 No 514Henry T RU Sporfoler 2-3 channel RU spans 52 ii has adiestable wing flaps S475 No 521Comet Jr Clipper Plus 35% RU Oki-limor oportster enne 2-cb RU spans 40 in$650 No 522Sorts PiOus RU Rewmder-ocale laps 40/60 engines spans 43 Two plan sheetsS1050 No 525HI-Tech 2002 RU Canard ducted-lan 45 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sportoter 035 motor spans 44 S475 No 553to RU AMA Class B 2-Meter Safiplane has 78W-in-span foam wingS725 No 565Avro 550 FE Mini-electric Scale 23 British utimlight spans 30 in$200 No 569Electroatreak RU Electric aembetic plane spano 44 moo 05 motorS550 No 570Busy Bee FE Pee Wee-30 plane 02 power spans 30 has euher sheet-hales sr haiti-op surfaces$400 No 572TR-260 RU Sport Scale Aumlotic plane 4-otmkn 60/65 power spans 96 in$1100 No 575Scorplon 60 RU Ken-fly sembatic plane 60 power spans 96 in51150 No 576Serendipltyl FE Indoor 028 mcard-holder spans 1775 5325 No 578Schwelzer 1-ZOB RU Ounster-scale Sailplane spans 125 Two plan sheets$1475 No 579Lockheed P35 CL Precislen Scale WiN II figleer twin 45s spans 65 Fonder flaps etc Thmo plan sheets 51800 No 580Pamall Pixie FE Rubber Scale GuIdes Age British biplane 112 scale spans 31 in5375 No581Gee Bee Model Y RU Golden Age Rnner spans 72 ix scale 00 power plan sheetsS1175 No 553Sportwegon RU Radio-fred sport FE model spans 54 ama 19115 engine$796 No 584Happy Days CL Intensedlete trainer/Stuoter opano 42 uses 25136 engine5575 No 555Dragonfly FE fligh-perfonsanca P-30 Rubber ship spans 30 weighs 50 gumsS496 No 556Snapdragon RU Fun-fly/sportster 29130 engimo opons 45 inS696 No 557PlIatius PC-9 CL Futile Scale/Stotter/sportster spans 96 ama 25/36 engine5550 No 585Merlsh RU Slope-Searing SailpImo spans 41 uses 2 RU chasseis5425 No 559Vlckera Wellewley RU Sport Scale WW II hamber spans 89 0 ama 40 4-cycln eagle Two plan sheets ne dxc$1250 No 590Bud Lke Laser Stunter CL Stonter scalelike spans 63 io uses 60 esgine Two plan sheets$1050 No 591Focke-Wulfi FW 190-A RU Sport Scale WW II fighter spmo 96 snax 35/45 2-stroke engine Two plan nht doc$1350 No 592ET CL trainar/sportster oma 00 electric power 6-cat battery pack Wingspan 24 in$475 No 593Taylorcraflt RU Spoil Scale lightplane hafids standard 2-placar clipped-wing air show stuntnr Spans either 7tPb 58 30/40 two-stroke 40140 four-stonke engine Two plan sheets no dacurrwntatlunS1000 No 554P-Si Black Widow UL Pufile Scale tiWil II twin-engine night tighter sma 19125 engine spans 49 inS800 No 595Sparrow RU Sportoter 25 engines spuos 43 inS650 No 596Tomahawk II CL Pufile Stonter ama 36 engine spnns 40 inS500 No 597Handley Page W8b FE Sulls mini-Electric twin-motor biplane spano 30 in$300 Circle numbers plans wish order 193 414 490 531 554 575 585 593 239 440 506 533 555 576 586 594 262 447 512 534 559 578 587 595 310 454 514 535 563 579 588 596 314 457 521 539 568 580 589 597 326 460 522 541 569 581 590 598 332 465 525 544 570 583 591 599 386 478 528 549 572 584 592 600 Plan pnce includes first Class postage US delivery Which Air Mail over 300 miles orders non-US address learn add $251 Air Mail osta e liandlin Ian Make check money order payable US funds drawn US bank Model Aviation c/a AMA 1810 Samuel Morse Dr Reston VA 22090 Please allow 3 6 Weeks delivery Please print carefullyEnclosed $ ______________________ NAME STREET CITY STATE ZIP AMA No ______________ span weight 1/circle radius opposing moment due yaw can also calculated described Part proportional span area airspeed2 yaw angle Equivalent Dihedral Angle yaw angle required achieve steady-state circle may calculated As suming moderate bank angles yaw gle function bank angle propor tional 1/area span weight 1/airspeed2 1/EDA 1/circle radius Baseline aircraft yaw angles presented enable estimation yaw angles other model aircraft Differences behavior different dihe dral types described V-dihedral wings may circled slowly parabolic polyhedral types Also V-dihedral wings have less tendency tip-stall Spiral stability described dis cussed Spiral stability may increased increasing dihedral lengthening vertical tail moment arm reducing area vertical stabilizer method approximately assess spiral stability presented Adequate spiral stability essential achieving maximum circling performance order plane spirally stable speeds must spirally stable its lowest speed Correction If difficulty following some Part 2 Dihedral article September 1988 issue its no small won der block type accidentally mispositioned Readers would like able follow proper continuity should note following Five colunm inches text page 174 starting second line second paragraph under Prototypical dihedral arrangements ending 12th line page 175 should read following text page 176 page 178 Also reference Figure 2 first line third full paragraph page 175 -should have Figure 6 regret errors Letters Editor Continued page 10 fore consider gliding fans very fortu nate have talents knowledge Byron Blakeslee appearing issue articles best What added bonus allow him sub mit find room print two gliding articles sometimes Last year again May 1988 issue super bonus four gliding articles excellent color photos dont know other model magazine produces such good quality both technically artisti cally Please accept congratulations Need less say will continue look forward months issue AB Steve Stevens Nanaimo BC Canada 180 Model Aviation 6 03 0 ciJ cJ 2~ toe -es 04 93 6c zo 0 93 C 0 V 9301 anea 0 0 0 5 Con lOon ae .to od os C 0 -SE 9363 C 4350 tuC tO 55 93 93 93 C 0 0

NO OCR TEXT NO OCR TEXT plane circles tighter banks up air speed increases Increased bank angle re duces span airplane relative circle axis thus reducing rolling-in mo ment increased speed also affects other things however analysis limited bank angles less about 300 fair approximation say no effects due bank angles effect high bank angles may seen tailing-off lines envelope Figure 3 bank angle effect lines would simply overlap Assuming bank angle limitation con sider variables independently wing area wingspan weight lift coefficient air speed yaw angle Equivalent Dihedral An gle circle radius bank angle con sider independently means vary variable time holding other var iables constant changing variable normally affects some oth ers turns out rolling-in moment due circling affected wing span weight circle radius mo ment proportional wing span2 weight l/circle radius fading fast hang get some meaty stuff shortly Reviewing quickly Part Two series rolling-out moment due yaw proportional wingspan wing area air speed2 yaw angle EDA compare sensitivity van ables rolling-in moment rolling-out moment can deduce fol lowing Yaw angle function bank gle steady-state circle proportional 1/wing area wingspan weight lIair speed2 l/EDA l/circle radius relationships will allow esti mate yaw airplane based charts explained below Examples will follow yaw angle plots Figures 3 4 show yaw angle required hold plane steady-state circle Figure 3 plots yaw angle function circle radius Figure 4 plots yaw angle function bank gle plots take account much complexity problem including effect bank angle increased speed bank angle effect ignored however en tire airplane has same sink rate wing has variable airspeed means inboard wing sees higher angle tack related inverse glide ra tio calculation typical Glider showed effect minor also complicates analysis immensely effect ignored plots show yaw single air plane flown variety weights speeds constant lift coefficient has 100 span 1000 sq area l0 EDA weights ranging about two seven pounds values especially lighter three airplanes typical sport RC Sailplanes Looking Figure 4 20 ftIsec 104 Model Aviation ADove rn-low curvajure maae VISIDICI As plane circles airatream passes over out board wing faster inboard wing tends make plane roll same time though vertical stabilizer tends align itself local flow means wing yaws outboard tends make plane roll out get variables right plane will circle stable fashion Below Low-dihedral aileron sailpianes have problem achieving spiral stability vertical stabilizer yaws airplane outboard insufficient dihedral produce net rollout moment especially true large lightweight aileron ships such 1 20-in-span Tango As resuit pilot must circle actively controlling rolling-in tendency top aileron Also tendency pilot increase circling airspeed well beyond optimum Improve spiral stability 03 025 02 LIFT Ib/005 span 015 01 005 -1 -08 -06 -04 -02 0 02 04 06 08 1 V-Dihedral - - APYal -Parabolic ML CL right tip WING STATION fraction semispan 0 -08 -06 -04 -02 0 02 left tipCL Figure 2 0406 08 right tip WING STATION fraction semispan Figure 1 Circling yawing shifts lift distribution outboard rolls plane inboard heavy line plotted represents lift distribution elliptical planform wing circling 30 bank angle fine line beneath lift distribution same wing level flight Extra lift due banking reflected greater average lift heavy line particular plot represents unyawed 100-Inspan 3-lb airplane 30 bank left circle Its level flight speed 20 ft/sec its speed bit higher create extra lift re quired bank angle Figure 2 Yawing outboard redistributes lift distribution Inboard balancing rolling-in moment Note lift distribution parabolic dihedral wing thin line almost symmetrical whereas V dihedral wing heavy line really loads up inboard left wing unloading left tip plot represents same airplane Figure 1 except now yawed outboard 870 model see has yaw some nine degrees circling 300 bank serious yaw Full-size airplanes use sideslip yaw dive brake us ing thermaling Now look what hap pens plane extreme floater fly ing 15 ftIsee 3O bank has yaw nearly 170 Talk about extra drag Calculating yaw angle Suppose have airplane has wing area in2 span weight b airspeed t/sec EDA ight typical FAT F3B-class Sailplane much would yaw com pared 30 ft/sec aircraft Figure 4 First ratio variables area /1000 span 100 weight 438 airspeed 0 EDA must also ratio circle radius proportional airspeed2 circle radius 2 above discussion know yaw must proportional 1/area span weight 1/airspeed2 1/EDA 1/cir cle radius Chaining variable ratios gether relative yaw must 1/110 x 120 x 0874 x 1/09332 x 1/050 x 1/0870 Going Figure 4 find 30 ft/sec airplane must yaw about 43 de grees new plane must yaw 252 x 43 degrees means typi cal F3B Sailplane must yaw outboard about 11 degrees circling 30-degree bank ailerons used hold up wing Since F3B Sailplanes have 30 dihedral clear effi cient thermaling top aileron must used actively pilot hold up inboard wing What have A-2 Nordic Glider cir cling 50-foot radiushow much must yaw Typical vital statistics wing area in2 span eight b airspeed t/sec EDA om pared 15 ft/sec airplane Figure 3 variable ratios would area 475/1000 span 00 weight 859 airspeed 5 EDA compute relative yaw ratios proportioned multiplied together Rela tive yaw 75 x 080 x 0484 x 1/09332 x 1/070 Figure 3 20 175 15 125 Yaw Angle 10 degrees 75 5 25 0 VolSft/sectJI VLI[i]iii J 175r j-.-I-J- 1 20 30 LU 175 15 II 125 Yaw Angie degrees 75 5 25 0 0 l0 203040 50 60 70 80 go 100 Figure 3Circle Radius feetFigure 4 Figure 3 Slower airplanes must yaw outboard lot plot shows yaw angle required circle steadily single airplane flown constant lift coefficient 10 variety weights Note yaw angle plotted against circle radius required yaw indepen dent weight until moderate bank angles reached example wingspan 100 wing area 1000 sq Equivalent Dihedral Angle 10g Vo speed airplane straight flight bank angle increases airspeed increases well weights different speeds slowest fastest 1659 lb 2531 lb 3306 lb 5165 lb 7438 lb Figure 4 As function bank angle slower airplanes must yaw much faster airplanes plot same airplanes shown Figure 3 except yaw angles plotted against bank angle instead circle radius Note maximum yaw angle reached bank angle 450 Beyond 450 wing becomes vertical difference airspeed over entire span diminishes very rapidly point Vo 5 75 20 25 30 6O 55 50 45 40 35 30 25 20 15 10 Dank Angle degrees October 1988 105 025 02 015 LIFT 1b/005 span 01 005 0 left tip Figure 1 find baseline 15 ft/sec airplane yaws about 600 circle radius 50 ft Nordic Glider must yaw 134 x 60 8030 Some Nordics use device creases angle attack inboard wing after tow release order hold up inboard wing much would wing above model have ro tated order eliminate required yaw Part series can calculate 8030 yaw wing 70 EDA gives 0980 change angle tack both wings achieve change wing must piv ot twice much about 200 General examples Now may clear can get yaw information baseline aircraft useful informa tion airplane Rather go through process plane range planes might consider ing following relationships may some use Again based sumption bank angle less 300 have same plane same lift coefficient different weights taken function circle radius yaw angle constant illustrated Figure 3 have same plane same lift coefficient different weights taken function bank angle yaw angle proportional 1/weight illustrated Figure 4 airplane proportionally scaled keeping wing loading same yaw angle function bank angle propor tional scale factor wing area weight kept con stant wingspan varied yaw gle function bank angle propor tional span span wing loading kept constant wing area varied yaw angle function bank angle con stant aspect ratio has no effect yaw angle span wing loading unchanged airplane kept same Equivalent Dihedral Angle varied yaw angle proportional 1/EDA span weight airspeed con stant wing area varied choosing between low high camber wing say yaw angle function bank angle proportional l/wing area High lift high aspect ratio wings yaw low camber low aspect ratio wings exact same airplane flown dif ferent airspeeds lift coefficients taken function circle radius yaw angle varies 1/airspeed2 Speeding up airplane really reduces amount yaw required exact same airplane flown dif ferent airspeed lift coefficient taken function bank angle yaw gle varies 1/airspeed4 As function bank angle yaw angle super sensitive airspeed Dihedral types three prototypical dihe dral types described briefly above de tail Part Two display some important dif ferences behavior circling Simply put V-dihedral wings have less tendency tip-stall polyhedral parabolic wings can flown lower speeds thermaling As planes circle planes yaw out board V-dihedral wing has same angle attack everywhere wing higher inboard wing less out board wing polyhedral wing has highest angle attack inboard tip progressing lowest outboard tip parabolically curved wing has smooth gradation angle attackhighest inboard tip lowest outboard tip Since dihedral angle tip panel polyhedral wing greater V dihedral wings dihedral angle inboard polyhedral tip panel greater angle attack inboard tip parabolic wing greater angle attack poses problem circling Nor mally models thennal near maximum lift coefficient close stall part wing gle attack will stall first limits minimum thermaling speed plane angle attack polyhedral wing greatest inboard tip panel panel limits maximum average lift coef ficient plane circling Like wise very tip parabolic wing lini its its average lift coefficient V dihedral wing limited entire board wing Since spread between maximum angle attack average angle attack least V-dihedral wings able fly slowest circling Parabolic wings have spread must circle fastest avoid stalling inboard tip advantage minor typical middle-weight mid-size RC Sailplanes Let us take example 20 ft/sec air plane Figure 4 300 bank angle also typical must yaw 960 informa tion presented Part can calculate V-dihedral inboard wing must have angle attack 1680 higher av erage angle attack polyhedral wing has tip panels 130 dihedral its inboard tip panel must have angle attack 220 higher average parabolic wing has its tips about 160 dihedral its inboard tip has angle attack about 270 higher average Continued page 175 r5 11 IIIII iilLj II IA J 5101520 Equivalent Dihedral Angle degrees 20 15 Yaw Angle 10 degrees S 0 IIIIII i1II1 III 0255075100125150175 Span inches 200 2530 Figure 6 FIgure 5 Yaw angle circle Inversely proportIonal Equivalent Dihedral Angle plot shows required yaw angle 20 ttIsec airplane used FIgures 3 4 bank angle 300 Major improvements can yaw angle Increasing dihedral say 5 10g less gain increasing tram say 20 250 Figure 6 nature bigger airplanes must yaw order remain stable theyre circling plot shows required yaw angle function wingspan 20 ft/sec airplane 100 Equivalent Dihedral Angle banked up 300 flying lift coefficient 10 Note required yaw angle proportional models wingspan 106 Model Aviation 20 18 16 14 12 Yaw Angle 10 degrees 8 6 4 2 0 Figure 5 Finally heartfelt salute order beautiful people gave selves make 1988 FAC possible successful addition Maxecuter ganizers special thanks Lin Juanita Reichel Tom Schmitt Bob Clemens Ma rie Rees Connie McSulskis Marian Mann Kathy Thomas Peg Paisley Shirley Kuenz Rich Hensel Pat Jupiter Gerry Helen Paisley Otto Kuhni Claude Powell Paul Spreiregen Western NY FF Society Geneseo National Warplane Museum Peck-Polymers Golden Age Reproduc tions Sea Glen Models Blue Swallow Mod els Flyline Models Flying Scale Inc well unsung volunteer timers go-fers helpers especially en thusiastic thanks superb contes tants willingly shared yourselves keep Free Flight Scale alive well growing Bladder/Weinreich Continued page 99 lines shorter reaction time re quired about same bigger contest models Phil Granderson Portland OR came fourth year has won contest twice before practiced playing video games air hockey also flew plane night training himself con trol model depending sight helps him concentrate opposi tion match Just important practice con struction models proper modifica tion engines wings con structed Styrofoam reinforced bal sa carbon fiber fiberglass strapping tape Stabs built lightness tail booms either built-up ones made carbon fiber arrow shafts Models have wingspans about 4 ft weigh 18 20 oz About half weight accounted engine engine mounts Like other Bladder Grabber partici pants Kott designs own planes re works engines putting brass cylinder liners aluminum pistons modi1ing crankshafts Most engines contest started out life Fox 35s Combat has come long way past 20 years Bob Carver remarked Com paring Combat plane 20 years ago today like comparing Model T new Porsche Carver has fly ing 25 years explained speeds have gone 80 120 mph engine power has risen one-half horsepower two Aerodynamics have changed airfoil shapes different moments better planes can turn tighter accelerate faster performance has improved reminded us has skill level pi lots' Ironically last years Nats winner Mark Smith Ft Worth TX found hes im proved models too much built new planes year quicker faster old ones used did fly well Smith rue fully explained Though didnt place years Bladder Grabber hes no quitter planning return next years Theres something about Combat flying just gets blood Bob Carver continues compete de spite never having won Bladder Grabber although year placed respectable seventh summed up way Its ultimate video game Its flier against another its strategy maneu vering evasion attack Its things actual fighter pilots have Ill give Bob last word too know youve alive says after youve flown Combat match As motto Combat observation would hard improve upon Dihedral/Beron-Rawdon Continued page 106 half-degree penalty polyhedral wing relative V-dihedral wing will force increase speed about 3% degree penalty parabolic wing rel ative V-wing will force 55% increase speed Because dihedral angle yaw angle reciprocal works out changing Equlvalent Dihedral Angle has no effect variations angle attack larger slower planes penalty severe Take 120-in-span 1000in2 25-lb plane thermals 175 ft/sec instance plane must yaw 150 300 bank angle V-dihedral plane will thermal 4% slower poly hedral plane 8% slower para bolic wing addition penalty imposed poly hedral parabolic wings steady-state circle another penalty imposed maneu vering circling particular initiat ing roll-out steady-state circle further loads up inboard panel tip loads up polyhedral parabolic wings order leave equal maneuvering margin top existing stall margin polyhedral parabolic wings must flown faster yet V-dihedral wing conclusion draw V-dihedral wings superior ther maling maneuvering thermaling contrast conclusion par abolic polyhedral wings superior steady-state rolling maneuvers mar gin superiority both cases very great important large slow airplanes Spiral stability Spiral stability refers ability airplane roll out cir cle rudder neutralized hold constant circle radius rud der held deflected plane very spirally stable will roll out circle quickly rudder centered will require substantial rudder deflection hold circle will fly straight still PRECISION MODEL PRODUCTS Made U S BARSTOCK ALUMINUM SPINNERS Pan NoSize fl-150B .. 1-1/2 TT-175B .. 1-314 TT-200-B TT-225-B .. 21/4 TT-226-B .. 2114 FAI 11-250-B .. 21/2 TT-251B . 21/2 FAI .. TI-275-B .. 23/4 TI276-B .. 23/4 FAt .. 11-300-B 11301-BFAIl 11325-B .. 3-1/4 l1-350B 3-1/2 11-375-B33/4. 11-400-B4 RetailApprox PriceWeight $1395058 02 149509502 1595100oz 169516002 189515002 189519002 2095170oz 229522002 249520002 269526002 289525002 3695340oz 4995470oz 599552002 6995570oz 3 Pieces Cone Back Plate Retainer Screw Note 3 4 Blade Spinners Available Sizes Add $300 Per Spinner PROP NUT ADAPTORS Pan No Size 11-140-A 28 11-147-A -28/7mm 11-610-A 10mm 11-710-A x 10mm 11-516-A 6-24 11-518-A . 5/16-24/8mm 11-810-A . Ox 10mm 11-825-AOx 125mm 11-375-A3/8-24 11-125-A10 x 125mm RetailApprox PriceWeight $495061 02 495 . 061 oz 495 . 063oz 495OB2oz 49507602 495 .076 02 495076oz 495075 02 595 .ll7oz 595 02 3 Pieces Nut Washer Machined Bushing Add $350 Shipping Handling Prices subject change notice ROMCO MFG INC OX 836 SOUTH HOUSTON TEXAS 77587 713 943-1867 October 1988 175 PlC Video Tape Vol 1 Basics 115 minutes total running time graat ducatLonal ualuc menckd clubs hobbj jJ$$YJkz\shop owners. Model AvIation Nov 1987 Only $1795 tax & shipping mci VISA M/C orders call 415 967-5134 Penn International Chemicals 943 Steirlin Rd Mt View CA 3 4 66 6666 666 6666666666666666666666666666666w 6 DUAL STRUT NICKEL PLATED NOSE GEAR iiiI I suIts Tooling P0 Box 95 ChampaIgn IL 61820 air indefinitely plane neutrally stable will remain circle con trols neutralized no rudder deflec tion required hold turn spi rally unstable airplane will circle tighter steeper controls neutral ized opposite rudder continudus ad justments required hold turn spirally unstable airplane will fly straight its ownit will gradually bank circle spiral down steepness tightness spiral determined degree spiral instability Free Flight models obviously must spirally stable ones arent will crash have limited experience Free Flights seems generous measure spiral stability would vir tue Nevertheless have seen successful models notably FM Power models appeared marginal respect have experience RC Sailplanes 1 am certain what exacfly best have flown spirally unstable air planes definitely unpleasant always try get away very difficult fly precisely other hand Sailplanes excess spiral stability require lot control input cir cle can give plane dull doggy feel may mask feel thermal present preference plane small-to-moderate amount spiral stability Once circle established such plane control input goes making adjustments seems easier sense thermal have seen circling airplane must yaw outboard certain amount avoid rolling spirally stable airplane will naturally yaw outboard amount two basic effects cause outboard yaw first due circular flight path plane second due variable airspeed over wing As plane circles its flight path streamlines curved Since vertical stabilizer aft wing sees dif ferent yaw angle wing vertical stabilizer approximately aligns itself flow airplane wing yaws out board effect illustrated pictures curvature flow can result remarkably large angles example imagine plane 25-ft-radius circle perimeter circle 157 ft distance between wing vertical stabi lizer three feet angle air flow between wing vertical stab approximately 3/157 x 3600 Thus absence other effects vertical stabilizer would align itself local flow airplane would yaw out board 690 Just un-yawed circling wing makes lift outboard panel also makes drag variation drag causes outboard yawing moment opposed lift vertical stabi lizer Lift vertical stabilizer gener ated yawing further outboard its neu tral zero lift angle principal variables spiral stability emerge natural yaw gle plane due its circular path de pends distance between wing vertical stabilizer circle ra dius yaw angle due variation wing drag depends degree varia tion drag turn depends circle radius wing section other fac tors size aspect ratio mo ment arm vertical stabilizer size moment arm vertical stabilizer characterized vertical tail volume quantified vertical tail area wing area x vertical tail moment arm wingspan aspect ratio vertical stabilizer also important since lift curve slope quite sensitive changes aspect ratio aspect ratio low Now see what makes plane yaw outboard other key piece Equiv alent Dihedral Angle Increasing dihe dral reduces amount plane must yaw avoid rolling achieve neutral spiral stability natural yaw angle plane assumes circling must equal angle required balance roll axis adjust spiral stability can either change angle plane natu rally yaws outboard can change angle plane must yaw avoid rolling BATT- CHEKBX Saves Time . 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also leave vertical tail mo ment arm three feet leave EDA 10 shrink vertical stab extra drag outboard wing can yaw plane outboard Exactly what size vertical stab must complex problem because large number variables number unknowns major var iable effect fuselage especially airplanes large long fuselages relative wing general models easier cut try accurately calculate some trade-offs can get spiral stability small vertical stab short moment arm can also get large small vertical stab long moment arm have too little vertical stab too little moment arm though airplane will have Dutch roll problems rhyth mic yaw-roll oscillation air plane looks pilot flying music waltz condition avoid Free Flight models often trimmed near condition however appears improve ability model center thermals itself perhaps because direction plane much affected what happening wing RC Safiplanes small verticals short moment arms will sluggish con trol because small vertical cannot gener ate much lift compound problem has little leverage plane addition such plane will poorly damped making precision flying difficult discussed Part series large vertical stab long moment arm will give RC models powerful control excellent damping disadvantage large surfaces have drag longer tail booms heavier Careful struc tural aerodynamic design can minimize disadvantages own preference toward larger verticals longer tail booms neat feature spiral stability works circle radii set up just stable 25-ft radius will still just stable 50-ft radius because amount plane must yaw pro portional 1/circle radius amount plane does yaw proportional 1/cirdc radius Keep mind depen dent variables some unpredictable dont expect perfection information see can estimate whether design will spi rally stable make effective adjustments have determine yaw gle required configuration de termine much yaw will occur effect flow curvature flow cur vature gives required yaw angle almost guaranteed have spiral stability need some out board yaw know vertical stab will have carefully sized best guess would typical RC Sailplanes can count plane yawing about two three degrees outboard very large vertical stabilizer would al low Some Free Flight Nordic models use very low aspect ratio verticals might allow something order six degrees guess remember Achieving spiral stability aileroncontrolled airplanes can problematic ample vertical stabilizer put reason able distance wing generous amount dihedral required achieve spiral stability turn causes tinwanted roll responses unintended yaw de flections such adverse yaw due aile rons crosswind takeoff perhaps gyroscopic coupling roll pitch axes Reducing size vertical stabi lizer may partially effective going too far can result very loose air plane Lengthening tail boom also helpful has its penalties weight drag An additional facet spiral stability pointed out Dr Andy Bauer described him paper National Free Flight Society Digest 1987 Note above required yaw angle circle given airplane very sensitive airspeed Faster airspeeds require substan tially less yaw angle means air plane may spirally stable low speeds may stable higher speeds Radio Control Free Right Gliders has great importance Free Flight mod els insufficient spiral stability cannot trimmed best glide elevator trimmed slow model optimum speed inadequate spiral stability model starts roll As does however gains speed improved spiral stability same time process begins circling higher less efficient speed model adequate spiral sta bility could have trimmed fly slower entering roll-in speedup cycle same effect occurs RC Sailplanes particularly ailerons low dihedral Such models unstable flying slowly auto matic tendency part pilot speed up thermaling thus degrading performance moral achieve maximum circling performance sure have adequate ample spiral stability effect also important considera tion RC power models especially trainexperience Great Performance Quartet DALOTEL 850 SPAN 69 InsWING AREA 830 sq ins CHIPMUNK 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Northeast Aerodynamics Northeast Screen Graphics .. 45 99 37 . 158 . 166 Pacer Tech179 Parrish Aircraft160 Peck-Polymers152 Pelican Enterprises160 Penn International Chem176 Pica Products15 Polks Hobby84 Progress Mfg Co151 Pro-Tune Corp176 RC Buyers Guide22 RC Extras157 RC Soaring Digest158 Radio South140 Red Max Fuel5 SR Batteries143 Safety Plus20 99 Satellite City30-31 Scale Model Research172 Scale Plans & Photo Ser171 Scande Research152 Schlueter Helicopters89 Sermos RC Snap Conn152 Shamrock Comp Imports .. 154 Sheldons Hobby Shop20 Sig Mfg Co18-19161 Sky Baby171 Skyline Hobby Mfg37 Bob Smith Industries47 53 Spirit Lake Hobbies16 Square Cut Tools138 StarBase Exchange167 Star Kraft160 Sullivan Products90-91 Sunshine Hobbies146 Suretech49171 T&D Fiberglass Spec142 Tatone Products Co92 Top Flite Models Inc93 Tower Hobbies6-7 Tru-Turn175 WE Technical Services8 WW Aeroplanes156 Wandit Mfg167 Williams Brothers47 Wilshire Model Center152 Windsor Propeller Co171 Wing Mfg Co166 World EnginesCover 4 YSFutaba159 Yale Hobby Mfg Inc157 Zim pro Marketing177 ers Spiral stability degraded air plane slowed design may have plenty stability buzzing around high speed may tend roll slowed landing approach plane spirally stable speeds must stable its slowest speed Summary conclusions Typical Sail plane models exhibit substantial yaw angles during circling flight circling airspeed variation over wing generates moment causes plane tend roll Dihedral air planes oppose yawing outside circle steady-state circle rolling-in moment balanced rolling out moment caused dihedral out board yaw angle rolling-in moment can accurately calculated moderate angles bank rolling-in moment proportional wing178 Model Aviation No 598 Coronet 150$850 RC-Assist O-T enlarged 1 500k spans 72 uses 40-sizefour-stroke engine SAM-legal 30 two-stroke engine No 599 Kansas Wakefield$475 FF O-T Rubber competitor spans 48 Both 1938/1939 versions No 600 deHavilland Rapide $575 CL Sport Scale biplane spans 351/2 uses two /2A engines No 193StIletto CL Stunt madel McOnnah winner 1976 1960 1982 FAI World Clumps$375 No 239Blue Birds RU Ken Willards fonnation plane 4-channel 16/15 power$375 No 282Crashmeeter CL Crash-punt trainer Iwo oizes1530 36/40 powerS125 No 3101930 Fleet Biplane RU Sport Scale 36140 4-channel Wingapan 56 scale Two sheetsS625 No 314Drake II RC Ken Wilards flyIng boat 3-channel 15-power Pp land umenable gearS375 No 326Taylor Cub RU Don SojIls Schoehiard-Scafo 0495 2-3 choannl Spans 50 inS350 No 332Zephyr RU Smati 2-channel ofider hand-leanch tow themtit slaps anaring S200 No 386Laaer 200 RU Sport Scale mptca champlonahip Aembatic 0w Uses 40 power 4-5 channel Two sheets$1075 No 414ElectrIc Sparley RU Elechic fon flier 00 motOr 3-channel RU o scaled-op 1939 ubber-pewer tanonteS850 No 440Csvellea- RU OkI-limor-tike now design has huge wing slew easy flights 36 por 3 ch Two sheets$1725 No 447112A Miss America RU Old-Toner Texaco modal 049 gfow 2-channets. No 454Sweet P30 FF Neat stick-and-tiune Outdoor Ruhher P-3D-class model contest-winner$296 No 457Spectra RU Eieclnc-power 05-san motor ama 3 dfifeunt wings oport asaring aembatics S700 No 4604-40 RU Sheelder-wing sport flier 4-cycle 43-size esgine 4 chaonels S696 No 465Blue Max II RU Fan-fly sportster 40-size enmo spans 52 Lightwieght stuctaw S700 No 475Buttercup RU Cute eRn sporfoter sees micu 2-ch RU puise-udder Spans 27 0201935 powerS300 No 490Weekender RU Low-wing sport fler 20-aloe 4-st uke eoglae opana 47 inS575 No 506Playmate RU Sport flier 3 RU channeis 16/25-olin engimo spans 50 inS650 No 512Extra 230 RU Olest Scale aceehatic plane spans 8 ft ama Onadra engine Two plan sheetsS1650 No 514Henry T RU Sporfoler 2-3 channel RU spans 52 ii has adiestable wing flaps S475 No 521Comet Jr Clipper Plus 35% RU Oki-limor oportster enne 2-cb RU spans 40 in$650 No 522Sorts PiOus RU Rewmder-ocale laps 40/60 engines spans 43 Two plan sheetsS1050 No 525HI-Tech 2002 RU Canard ducted-lan 45 engimo spmo 36 Two sheetsS1000 No 528Swallow RU Lightweighl hotdugger 40-size foor-otmke engima spans 96 0$025 No 531TerrIble Coupe FE Robber-powered Coups dlriieer spans 40 contest-winnerS475 No 533Cessna C-37 RU Schoolyard Scale fomoas 300 plane 009110 power 2-ch spans 42 inS596 No 5341935 Challenger RU Tenaca OKI-Timor spans 47 040 engine 2-channel RUS550 No 535Atrix RU MSIA Ulmo 0 Sailplane spans 110 ama 4-channel RU system 25 No 539SImilar SlowMotlon 15 RU Taillees flying wing 15 engima spans 00 uses 3-oh RUS350 No 541Parakeet RU Sport leplane 19125 engines 3-channel RU equipment spans 42 inS675 No 544Heron RU Sf Winters sport Electric geared 075 motor 3 RU ch spans 65 inS575 No 549Cricket RU Sport scaleika br 20-size two- four-stinks engine spans 40 inS675 No 554Super Doubler II RU Spert Aeuhaons4ylon 49146 four-stinks engine spano 57 in5576 No 555Double Duly RU Basic/advanced trainer 19115 engima spans either 67 50 Two plan sheetsS1075 No 559Low Voltage RU Elechic-power sportoter 035 motor spans 44 S475 No 553to RU AMA Class B 2-Meter Safiplane has 78W-in-span foam wingS725 No 565Avro 550 FE Mini-electric Scale 23 British utimlight spans 30 in$200 No 569Electroatreak RU Electric aembetic plane spano 44 moo 05 motorS550 No 570Busy Bee FE Pee Wee-30 plane 02 power spans 30 has euher sheet-hales sr haiti-op surfaces$400 No 572TR-260 RU Sport Scale Aumlotic plane 4-otmkn 60/65 power spans 96 in$1100 No 575Scorplon 60 RU Ken-fly sembatic plane 60 power spans 96 in51150 No 576Serendipltyl FE Indoor 028 mcard-holder spans 1775 5325 No 578Schwelzer 1-ZOB RU Ounster-scale Sailplane spans 125 Two plan sheets$1475 No 579Lockheed P35 CL Precislen Scale WiN II figleer twin 45s spans 65 Fonder flaps etc Thmo plan sheets 51800 No 580Pamall Pixie FE Rubber Scale GuIdes Age British biplane 112 scale spans 31 in5375 No581Gee Bee Model Y RU Golden Age Rnner spans 72 ix scale 00 power plan sheetsS1175 No 553Sportwegon RU Radio-fred sport FE model spans 54 ama 19115 engine$796 No 584Happy Days CL Intensedlete trainer/Stuoter opano 42 uses 25136 engine5575 No 555Dragonfly FE fligh-perfonsanca P-30 Rubber ship spans 30 weighs 50 gumsS496 No 556Snapdragon RU Fun-fly/sportster 29130 engimo opons 45 inS696 No 557PlIatius PC-9 CL Futile Scale/Stotter/sportster spans 96 ama 25/36 engine5550 No 585Merlsh RU Slope-Searing SailpImo spans 41 uses 2 RU chasseis5425 No 559Vlckera Wellewley RU Sport Scale WW II hamber spans 89 0 ama 40 4-cycln eagle Two plan sheets ne dxc$1250 No 590Bud Lke Laser Stunter CL Stonter scalelike spans 63 io uses 60 esgine Two plan sheets$1050 No 591Focke-Wulfi FW 190-A RU Sport Scale WW II fighter spmo 96 snax 35/45 2-stroke engine Two plan nht doc$1350 No 592ET CL trainar/sportster oma 00 electric power 6-cat battery pack Wingspan 24 in$475 No 593Taylorcraflt RU Spoil Scale lightplane hafids standard 2-placar clipped-wing air show stuntnr Spans either 7tPb 58 30/40 two-stroke 40140 four-stonke engine Two plan sheets no dacurrwntatlunS1000 No 554P-Si Black Widow UL Pufile Scale tiWil II twin-engine night tighter sma 19125 engine spans 49 inS800 No 595Sparrow RU Sportoter 25 engines spuos 43 inS650 No 596Tomahawk II CL Pufile Stonter ama 36 engine spnns 40 inS500 No 597Handley Page W8b FE Sulls mini-Electric twin-motor biplane spano 30 in$300 Circle numbers plans wish order 193 414 490 531 554 575 585 593 239 440 506 533 555 576 586 594 262 447 512 534 559 578 587 595 310 454 514 535 563 579 588 596 314 457 521 539 568 580 589 597 326 460 522 541 569 581 590 598 332 465 525 544 570 583 591 599 386 478 528 549 572 584 592 600 Plan pnce includes first Class postage US delivery Which Air Mail over 300 miles orders non-US address learn add $251 Air Mail osta e liandlin Ian Make check money order payable US funds drawn US bank Model Aviation c/a AMA 1810 Samuel Morse Dr Reston VA 22090 Please allow 3 6 Weeks delivery Please print carefullyEnclosed $ ______________________ NAME STREET CITY STATE ZIP AMA No ______________ span weight 1/circle radius opposing moment due yaw can also calculated described Part proportional span area airspeed2 yaw angle Equivalent Dihedral Angle yaw angle required achieve steady-state circle may calculated As suming moderate bank angles yaw gle function bank angle propor tional 1/area span weight 1/airspeed2 1/EDA 1/circle radius Baseline aircraft yaw angles presented enable estimation yaw angles other model aircraft Differences behavior different dihe dral types described V-dihedral wings may circled slowly parabolic polyhedral types Also V-dihedral wings have less tendency tip-stall Spiral stability described dis cussed Spiral stability may increased increasing dihedral lengthening vertical tail moment arm reducing area vertical stabilizer method approximately assess spiral stability presented Adequate spiral stability essential achieving maximum circling performance order plane spirally stable speeds must spirally stable its lowest speed Correction If difficulty following some Part 2 Dihedral article September 1988 issue its no small won der block type accidentally mispositioned Readers would like able follow proper continuity should note following Five colunm inches text page 174 starting second line second paragraph under Prototypical dihedral arrangements ending 12th line page 175 should read following text page 176 page 178 Also reference Figure 2 first line third full paragraph page 175 -should have Figure 6 regret errors Letters Editor Continued page 10 fore consider gliding fans very fortu nate have talents knowledge Byron Blakeslee appearing issue articles best What added bonus allow him sub mit find room print two gliding articles sometimes Last year again May 1988 issue super bonus four gliding articles excellent color photos dont know other model magazine produces such good quality both technically artisti cally Please accept congratulations Need less say will continue look forward months issue AB Steve Stevens Nanaimo BC Canada 180 Model Aviation 6 03 0 ciJ cJ 2~ toe -es 04 93 6c zo 0 93 C 0 V 9301 anea 0 0 0 5 Con lOon ae .to od os C 0 -SE 9363 C 4350 tuC tO 55 93 93 93 C 0 0

NO OCR TEXT NO OCR TEXT plane circles tighter banks up air speed increases Increased bank angle re duces span airplane relative circle axis thus reducing rolling-in mo ment increased speed also affects other things however analysis limited bank angles less about 300 fair approximation say no effects due bank angles effect high bank angles may seen tailing-off lines envelope Figure 3 bank angle effect lines would simply overlap Assuming bank angle limitation con sider variables independently wing area wingspan weight lift coefficient air speed yaw angle Equivalent Dihedral An gle circle radius bank angle con sider independently means vary variable time holding other var iables constant changing variable normally affects some oth ers turns out rolling-in moment due circling affected wing span weight circle radius mo ment proportional wing span2 weight l/circle radius fading fast hang get some meaty stuff shortly Reviewing quickly Part Two series rolling-out moment due yaw proportional wingspan wing area air speed2 yaw angle EDA compare sensitivity van ables rolling-in moment rolling-out moment can deduce fol lowing Yaw angle function bank gle steady-state circle proportional 1/wing area wingspan weight lIair speed2 l/EDA l/circle radius relationships will allow esti mate yaw airplane based charts explained below Examples will follow yaw angle plots Figures 3 4 show yaw angle required hold plane steady-state circle Figure 3 plots yaw angle function circle radius Figure 4 plots yaw angle function bank gle plots take account much complexity problem including effect bank angle increased speed bank angle effect ignored however en tire airplane has same sink rate wing has variable airspeed means inboard wing sees higher angle tack related inverse glide ra tio calculation typical Glider showed effect minor also complicates analysis immensely effect ignored plots show yaw single air plane flown variety weights speeds constant lift coefficient has 100 span 1000 sq area l0 EDA weights ranging about two seven pounds values especially lighter three airplanes typical sport RC Sailplanes Looking Figure 4 20 ftIsec 104 Model Aviation ADove rn-low curvajure maae VISIDICI As plane circles airatream passes over out board wing faster inboard wing tends make plane roll same time though vertical stabilizer tends align itself local flow means wing yaws outboard tends make plane roll out get variables right plane will circle stable fashion Below Low-dihedral aileron sailpianes have problem achieving spiral stability vertical stabilizer yaws airplane outboard insufficient dihedral produce net rollout moment especially true large lightweight aileron ships such 1 20-in-span Tango As resuit pilot must circle actively controlling rolling-in tendency top aileron Also tendency pilot increase circling airspeed well beyond optimum Improve spiral stability 03 025 02 LIFT Ib/005 span 015 01 005 -1 -08 -06 -04 -02 0 02 04 06 08 1 V-Dihedral - - APYal -Parabolic ML CL right tip WING STATION fraction semispan 0 -08 -06 -04 -02 0 02 left tipCL Figure 2 0406 08 right tip WING STATION fraction semispan Figure 1 Circling yawing shifts lift distribution outboard rolls plane inboard heavy line plotted represents lift distribution elliptical planform wing circling 30 bank angle fine line beneath lift distribution same wing level flight Extra lift due banking reflected greater average lift heavy line particular plot represents unyawed 100-Inspan 3-lb airplane 30 bank left circle Its level flight speed 20 ft/sec its speed bit higher create extra lift re quired bank angle Figure 2 Yawing outboard redistributes lift distribution Inboard balancing rolling-in moment Note lift distribution parabolic dihedral wing thin line almost symmetrical whereas V dihedral wing heavy line really loads up inboard left wing unloading left tip plot represents same airplane Figure 1 except now yawed outboard 870 model see has yaw some nine degrees circling 300 bank serious yaw Full-size airplanes use sideslip yaw dive brake us ing thermaling Now look what hap pens plane extreme floater fly ing 15 ftIsee 3O bank has yaw nearly 170 Talk about extra drag Calculating yaw angle Suppose have airplane has wing area in2 span weight b airspeed t/sec EDA ight typical FAT F3B-class Sailplane much would yaw com pared 30 ft/sec aircraft Figure 4 First ratio variables area /1000 span 100 weight 438 airspeed 0 EDA must also ratio circle radius proportional airspeed2 circle radius 2 above discussion know yaw must proportional 1/area span weight 1/airspeed2 1/EDA 1/cir cle radius Chaining variable ratios gether relative yaw must 1/110 x 120 x 0874 x 1/09332 x 1/050 x 1/0870 Going Figure 4 find 30 ft/sec airplane must yaw about 43 de grees new plane must yaw 252 x 43 degrees means typi cal F3B Sailplane must yaw outboard about 11 degrees circling 30-degree bank ailerons used hold up wing Since F3B Sailplanes have 30 dihedral clear effi cient thermaling top aileron must used actively pilot hold up inboard wing What have A-2 Nordic Glider cir cling 50-foot radiushow much must yaw Typical vital statistics wing area in2 span eight b airspeed t/sec EDA om pared 15 ft/sec airplane Figure 3 variable ratios would area 475/1000 span 00 weight 859 airspeed 5 EDA compute relative yaw ratios proportioned multiplied together Rela tive yaw 75 x 080 x 0484 x 1/09332 x 1/070 Figure 3 20 175 15 125 Yaw Angle 10 degrees 75 5 25 0 VolSft/sectJI VLI[i]iii J 175r j-.-I-J- 1 20 30 LU 175 15 II 125 Yaw Angie degrees 75 5 25 0 0 l0 203040 50 60 70 80 go 100 Figure 3Circle Radius feetFigure 4 Figure 3 Slower airplanes must yaw outboard lot plot shows yaw angle required circle steadily single airplane flown constant lift coefficient 10 variety weights Note yaw angle plotted against circle radius required yaw indepen dent weight until moderate bank angles reached example wingspan 100 wing area 1000 sq Equivalent Dihedral Angle 10g Vo speed airplane straight flight bank angle increases airspeed increases well weights different speeds slowest fastest 1659 lb 2531 lb 3306 lb 5165 lb 7438 lb Figure 4 As function bank angle slower airplanes must yaw much faster airplanes plot same airplanes shown Figure 3 except yaw angles plotted against bank angle instead circle radius Note maximum yaw angle reached bank angle 450 Beyond 450 wing becomes vertical difference airspeed over entire span diminishes very rapidly point Vo 5 75 20 25 30 6O 55 50 45 40 35 30 25 20 15 10 Dank Angle degrees October 1988 105 025 02 015 LIFT 1b/005 span 01 005 0 left tip Figure 1 find baseline 15 ft/sec airplane yaws about 600 circle radius 50 ft Nordic Glider must yaw 134 x 60 8030 Some Nordics use device creases angle attack inboard wing after tow release order hold up inboard wing much would wing above model have ro tated order eliminate required yaw Part series can calculate 8030 yaw wing 70 EDA gives 0980 change angle tack both wings achieve change wing must piv ot twice much about 200 General examples Now may clear can get yaw information baseline aircraft useful informa tion airplane Rather go through process plane range planes might consider ing following relationships may some use Again based sumption bank angle less 300 have same plane same lift coefficient different weights taken function circle radius yaw angle constant illustrated Figure 3 have same plane same lift coefficient different weights taken function bank angle yaw angle proportional 1/weight illustrated Figure 4 airplane proportionally scaled keeping wing loading same yaw angle function bank angle propor tional scale factor wing area weight kept con stant wingspan varied yaw gle function bank angle propor tional span span wing loading kept constant wing area varied yaw angle function bank angle con stant aspect ratio has no effect yaw angle span wing loading unchanged airplane kept same Equivalent Dihedral Angle varied yaw angle proportional 1/EDA span weight airspeed con stant wing area varied choosing between low high camber wing say yaw angle function bank angle proportional l/wing area High lift high aspect ratio wings yaw low camber low aspect ratio wings exact same airplane flown dif ferent airspeeds lift coefficients taken function circle radius yaw angle varies 1/airspeed2 Speeding up airplane really reduces amount yaw required exact same airplane flown dif ferent airspeed lift coefficient taken function bank angle yaw gle varies 1/airspeed4 As function bank angle yaw angle super sensitive airspeed Dihedral types three prototypical dihe dral types described briefly above de tail Part Two display some important dif ferences behavior circling Simply put V-dihedral wings have less tendency tip-stall polyhedral parabolic wings can flown lower speeds thermaling As planes circle planes yaw out board V-dihedral wing has same angle attack everywhere wing higher inboard wing less out board wing polyhedral wing has highest angle attack inboard tip progressing lowest outboard tip parabolically curved wing has smooth gradation angle attackhighest inboard tip lowest outboard tip Since dihedral angle tip panel polyhedral wing greater V dihedral wings dihedral angle inboard polyhedral tip panel greater angle attack inboard tip parabolic wing greater angle attack poses problem circling Nor mally models thennal near maximum lift coefficient close stall part wing gle attack will stall first limits minimum thermaling speed plane angle attack polyhedral wing greatest inboard tip panel panel limits maximum average lift coef ficient plane circling Like wise very tip parabolic wing lini its its average lift coefficient V dihedral wing limited entire board wing Since spread between maximum angle attack average angle attack least V-dihedral wings able fly slowest circling Parabolic wings have spread must circle fastest avoid stalling inboard tip advantage minor typical middle-weight mid-size RC Sailplanes Let us take example 20 ft/sec air plane Figure 4 300 bank angle also typical must yaw 960 informa tion presented Part can calculate V-dihedral inboard wing must have angle attack 1680 higher av erage angle attack polyhedral wing has tip panels 130 dihedral its inboard tip panel must have angle attack 220 higher average parabolic wing has its tips about 160 dihedral its inboard tip has angle attack about 270 higher average Continued page 175 r5 11 IIIII iilLj II IA J 5101520 Equivalent Dihedral Angle degrees 20 15 Yaw Angle 10 degrees S 0 IIIIII i1II1 III 0255075100125150175 Span inches 200 2530 Figure 6 FIgure 5 Yaw angle circle Inversely proportIonal Equivalent Dihedral Angle plot shows required yaw angle 20 ttIsec airplane used FIgures 3 4 bank angle 300 Major improvements can yaw angle Increasing dihedral say 5 10g less gain increasing tram say 20 250 Figure 6 nature bigger airplanes must yaw order remain stable theyre circling plot shows required yaw angle function wingspan 20 ft/sec airplane 100 Equivalent Dihedral Angle banked up 300 flying lift coefficient 10 Note required yaw angle proportional models wingspan 106 Model Aviation 20 18 16 14 12 Yaw Angle 10 degrees 8 6 4 2 0 Figure 5 Finally heartfelt salute order beautiful people gave selves make 1988 FAC possible successful addition Maxecuter ganizers special thanks Lin Juanita Reichel Tom Schmitt Bob Clemens Ma rie Rees Connie McSulskis Marian Mann Kathy Thomas Peg Paisley Shirley Kuenz Rich Hensel Pat Jupiter Gerry Helen Paisley Otto Kuhni Claude Powell Paul Spreiregen Western NY FF Society Geneseo National Warplane Museum Peck-Polymers Golden Age Reproduc tions Sea Glen Models Blue Swallow Mod els Flyline Models Flying Scale Inc well unsung volunteer timers go-fers helpers especially en thusiastic thanks superb contes tants willingly shared yourselves keep Free Flight Scale alive well growing Bladder/Weinreich Continued page 99 lines shorter reaction time re quired about same bigger contest models Phil Granderson Portland OR came fourth year has won contest twice before practiced playing video games air hockey also flew plane night training himself con trol model depending sight helps him concentrate opposi tion match Just important practice con struction models proper modifica tion engines wings con structed Styrofoam reinforced bal sa carbon fiber fiberglass strapping tape Stabs built lightness tail booms either built-up ones made carbon fiber arrow shafts Models have wingspans about 4 ft weigh 18 20 oz About half weight accounted engine engine mounts Like other Bladder Grabber partici pants Kott designs own planes re works engines putting brass cylinder liners aluminum pistons modi1ing crankshafts Most engines contest started out life Fox 35s Combat has come long way past 20 years Bob Carver remarked Com paring Combat plane 20 years ago today like comparing Model T new Porsche Carver has fly ing 25 years explained speeds have gone 80 120 mph engine power has risen one-half horsepower two Aerodynamics have changed airfoil shapes different moments better planes can turn tighter accelerate faster performance has improved reminded us has skill level pi lots' Ironically last years Nats winner Mark Smith Ft Worth TX found hes im proved models too much built new planes year quicker faster old ones used did fly well Smith rue fully explained Though didnt place years Bladder Grabber hes no quitter planning return next years Theres something about Combat flying just gets blood Bob Carver continues compete de spite never having won Bladder Grabber although year placed respectable seventh summed up way Its ultimate video game Its flier against another its strategy maneu vering evasion attack Its things actual fighter pilots have Ill give Bob last word too know youve alive says after youve flown Combat match As motto Combat observation would hard improve upon Dihedral/Beron-Rawdon Continued page 106 half-degree penalty polyhedral wing relative V-dihedral wing will force increase speed about 3% degree penalty parabolic wing rel ative V-wing will force 55% increase speed Because dihedral angle yaw angle reciprocal works out changing Equlvalent Dihedral Angle has no effect variations angle attack larger slower planes penalty severe Take 120-in-span 1000in2 25-lb plane thermals 175 ft/sec instance plane must yaw 150 300 bank angle V-dihedral plane will thermal 4% slower poly hedral plane 8% slower para bolic wing addition penalty imposed poly hedral parabolic wings steady-state circle another penalty imposed maneu vering circling particular initiat ing roll-out steady-state circle further loads up inboard panel tip loads up polyhedral parabolic wings order leave equal maneuvering margin top existing stall margin polyhedral parabolic wings must flown faster yet V-dihedral wing conclusion draw V-dihedral wings superior ther maling maneuvering thermaling contrast conclusion par abolic polyhedral wings superior steady-state rolling maneuvers mar gin superiority both cases very great important large slow airplanes Spiral stability Spiral stability refers ability airplane roll out cir cle rudder neutralized hold constant circle radius rud der held deflected plane very spirally stable will roll out circle quickly rudder centered will require substantial rudder deflection hold circle will fly straight still PRECISION MODEL PRODUCTS Made U S BARSTOCK ALUMINUM SPINNERS Pan NoSize fl-150B .. 1-1/2 TT-175B .. 1-314 TT-200-B TT-225-B .. 21/4 TT-226-B .. 2114 FAI 11-250-B .. 21/2 TT-251B . 21/2 FAI .. TI-275-B .. 23/4 TI276-B .. 23/4 FAt .. 11-300-B 11301-BFAIl 11325-B .. 3-1/4 l1-350B 3-1/2 11-375-B33/4. 11-400-B4 RetailApprox PriceWeight $1395058 02 149509502 1595100oz 169516002 189515002 189519002 2095170oz 229522002 249520002 269526002 289525002 3695340oz 4995470oz 599552002 6995570oz 3 Pieces Cone Back Plate Retainer Screw Note 3 4 Blade Spinners Available Sizes Add $300 Per Spinner PROP NUT ADAPTORS Pan No Size 11-140-A 28 11-147-A -28/7mm 11-610-A 10mm 11-710-A x 10mm 11-516-A 6-24 11-518-A . 5/16-24/8mm 11-810-A . Ox 10mm 11-825-AOx 125mm 11-375-A3/8-24 11-125-A10 x 125mm RetailApprox PriceWeight $495061 02 495 . 061 oz 495 . 063oz 495OB2oz 49507602 495 .076 02 495076oz 495075 02 595 .ll7oz 595 02 3 Pieces Nut Washer Machined Bushing Add $350 Shipping Handling Prices subject change notice ROMCO MFG INC OX 836 SOUTH HOUSTON TEXAS 77587 713 943-1867 October 1988 175 PlC Video Tape Vol 1 Basics 115 minutes total running time graat ducatLonal ualuc menckd clubs hobbj jJ$$YJkz\shop owners. Model AvIation Nov 1987 Only $1795 tax & shipping mci VISA M/C orders call 415 967-5134 Penn International Chemicals 943 Steirlin Rd Mt View CA 3 4 66 6666 666 6666666666666666666666666666666w 6 DUAL STRUT NICKEL PLATED NOSE GEAR iiiI I suIts Tooling P0 Box 95 ChampaIgn IL 61820 air indefinitely plane neutrally stable will remain circle con trols neutralized no rudder deflec tion required hold turn spi rally unstable airplane will circle tighter steeper controls neutral ized opposite rudder continudus ad justments required hold turn spirally unstable airplane will fly straight its ownit will gradually bank circle spiral down steepness tightness spiral determined degree spiral instability Free Flight models obviously must spirally stable ones arent will crash have limited experience Free Flights seems generous measure spiral stability would vir tue Nevertheless have seen successful models notably FM Power models appeared marginal respect have experience RC Sailplanes 1 am certain what exacfly best have flown spirally unstable air planes definitely unpleasant always try get away very difficult fly precisely other hand Sailplanes excess spiral stability require lot control input cir cle can give plane dull doggy feel may mask feel thermal present preference plane small-to-moderate amount spiral stability Once circle established such plane control input goes making adjustments seems easier sense thermal have seen circling airplane must yaw outboard certain amount avoid rolling spirally stable airplane will naturally yaw outboard amount two basic effects cause outboard yaw first due circular flight path plane second due variable airspeed over wing As plane circles its flight path streamlines curved Since vertical stabilizer aft wing sees dif ferent yaw angle wing vertical stabilizer approximately aligns itself flow airplane wing yaws out board effect illustrated pictures curvature flow can result remarkably large angles example imagine plane 25-ft-radius circle perimeter circle 157 ft distance between wing vertical stabi lizer three feet angle air flow between wing vertical stab approximately 3/157 x 3600 Thus absence other effects vertical stabilizer would align itself local flow airplane would yaw out board 690 Just un-yawed circling wing makes lift outboard panel also makes drag variation drag causes outboard yawing moment opposed lift vertical stabi lizer Lift vertical stabilizer gener ated yawing further outboard its neu tral zero lift angle principal variables spiral stability emerge natural yaw gle plane due its circular path de pends distance between wing vertical stabilizer circle ra dius yaw angle due variation wing drag depends degree varia tion drag turn depends circle radius wing section other fac tors size aspect ratio mo ment arm vertical stabilizer size moment arm vertical stabilizer characterized vertical tail volume quantified vertical tail area wing area x vertical tail moment arm wingspan aspect ratio vertical stabilizer also important since lift curve slope quite sensitive changes aspect ratio aspect ratio low Now see what makes plane yaw outboard other key piece Equiv alent Dihedral Angle Increasing dihe dral reduces amount plane must yaw avoid rolling achieve neutral spiral stability natural yaw angle plane assumes circling must equal angle required balance roll axis adjust spiral stability can either change angle plane natu rally yaws outboard can change angle plane must yaw avoid rolling BATT- CHEKBX Saves Time . 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Control Line Products Modelers serving Modelers shing Friend ToolsAdiuslahle Rudder turns Control Horns ControlLines 4 HeansiutyleltcranhsHandles AdiustableEeadoutGoides Ctassic Kits Custom Motor Mounts much ouch Aluminum loserts UNSURPASSED AtAtlitGUARANTEED SATISFACTION Send same address $AAA receive now espanded catalog will get $2 AK otl ynnr first order Craftsman Models Inc 3 Woooie Odm 4u074 dea o oquiries united An example know Figure 3 l00-in-span 20-ft/sec airplane must yaw outboard 96 achieve equilibrium circling 25-ft radius put very large vertical stabilizer 30 ft back wing know above calculation plane will yaw outboard 69 means will roll could lengthen tail moment arm until yaw angles least matched 50-in tail moment arm pretty long l00-in-span Sailplane tail mo ment 30% 40% wingspan typical RC Sailplanes although Free Flights tend longer Another solution would increase dihedral angle 100 EDA 96/69 x 10 reasonable solution remember have very large ver tical stabilizer could also leave vertical tail mo ment arm three feet leave EDA 10 shrink vertical stab extra drag outboard wing can yaw plane outboard Exactly what size vertical stab must complex problem because large number variables number unknowns major var iable effect fuselage especially airplanes large long fuselages relative wing general models easier cut try accurately calculate some trade-offs can get spiral stability small vertical stab short moment arm can also get large small vertical stab long moment arm have too little vertical stab too little moment arm though airplane will have Dutch roll problems rhyth mic yaw-roll oscillation air plane looks pilot flying music waltz condition avoid Free Flight models often trimmed near condition however appears improve ability model center thermals itself perhaps because direction plane much affected what happening wing RC Safiplanes small verticals short moment arms will sluggish con trol because small vertical cannot gener ate much lift compound problem has little leverage plane addition such plane will poorly damped making precision flying difficult discussed Part series large vertical stab long moment arm will give RC models powerful control excellent damping disadvantage large surfaces have drag longer tail booms heavier Careful struc tural aerodynamic design can minimize disadvantages own preference toward larger verticals longer tail booms neat feature spiral stability works circle radii set up just stable 25-ft radius will still just stable 50-ft radius because amount plane must yaw pro portional 1/circle radius amount plane does yaw proportional 1/cirdc radius Keep mind depen dent variables some unpredictable dont expect perfection information see can estimate whether design will spi rally stable make effective adjustments have determine yaw gle required configuration de termine much yaw will occur effect flow curvature flow cur vature gives required yaw angle almost guaranteed have spiral stability need some out board yaw know vertical stab will have carefully sized best guess would typical RC Sailplanes can count plane yawing about two three degrees outboard very large vertical stabilizer would al low Some Free Flight Nordic models use very low aspect ratio verticals might allow something order six degrees guess remember Achieving spiral stability aileroncontrolled airplanes can problematic ample vertical stabilizer put reason able distance wing generous amount dihedral required achieve spiral stability turn causes tinwanted roll responses unintended yaw de flections such adverse yaw due aile rons crosswind takeoff perhaps gyroscopic coupling roll pitch axes Reducing size vertical stabi lizer may partially effective going too far can result very loose air plane Lengthening tail boom also helpful has its penalties weight drag An additional facet spiral stability pointed out Dr Andy Bauer described him paper National Free Flight Society Digest 1987 Note above required yaw angle circle given airplane very sensitive airspeed Faster airspeeds require substan tially less yaw angle means air plane may spirally stable low speeds may stable higher speeds Radio Control Free Right Gliders has great importance Free Flight mod els insufficient spiral stability cannot trimmed best glide elevator trimmed slow model optimum speed inadequate spiral stability model starts roll As does however gains speed improved spiral stability same time process begins circling higher less efficient speed model adequate spiral sta bility could have trimmed fly slower entering roll-in speedup cycle same effect occurs RC Sailplanes particularly ailerons low dihedral Such models unstable flying slowly auto matic tendency part pilot speed up thermaling thus degrading performance moral achieve maximum circling performance sure have adequate ample spiral stability effect also important considera tion RC power models especially trainexperience Great Performance Quartet DALOTEL 850 SPAN 69 InsWING AREA 830 sq ins CHIPMUNK 850 SPAN 70 insWING AREA 850 sq ins SPAN 76 SPAN 72 ins IF EXTRA 230 WING AREA 900 sq ins ZLIN 526 WING AREA 900 sq ins series Sport Scale Balsa ARF Airplanes 120-4 cycle equivalent motors See RCHTA Show October 14-16 1988 available direct select hobby shops c ZIMP ROMARKETINO 1 PO BOX 3076 OAK RIDGE TN 37830 PHONE 615-482-6188 October 1988 177 ADVERTISERS INDEX 4-M Company 16 AH Designs51 AMA Employment4 AMA Membership141 AMA Museum170 Ace Radio Control41 Aerodrome Models142 Aero Plans N Parts156 Aerospace Composite Prod Air Champ Models168 Airtronics2 AI-tec Su-pr-Line Prod40 American Sailplane Des171 Astro Flight9 B&P Associates51 Quay Barber Models152 Bell Rock Industries138 Berkeley Trading Co158 Blue Ridge Mach& Tools .. 172 Bolar Heli Research146 Byron Originals80 C&C Electronics53 Campbell Tools Co171 Carlson Engine Imports172 Circus Hobbies162-164 Classic Glass49 Cleveland Model Supply22 Eric Clutton171 Colorado Model Products16 Coverite156 Cox Hobbies94 Craftsman Models Inc176 Crenshaw Aero43 Cressline Model Products .. 174 DGA Designs170 D&R Aircraft Mfg47 DP Systems172 Davey Systems Corp153 Du-Bro Products Inc78-79 Eastcraft Specialty Products . 43 Elden-Ken Electronics51 Electric Model Co168 Electronic Design Corp167 FAI Model Supply168 FHS Supply Inc5 Flight Components146 Flights Fancy Aeromodel Florio Flyer176 Flyline Models158 Foam Scale Models167 ADVERTISERS INDEX ADVERTISERS INDEX ADVERTISERS INDEX Fourmost Products49 Fox Mfg Co10 Fults Dual Struts176 Futaba Corp America21 GM Precision Products Gator RC Products Carl Goldberg Models Great Planes 30 165 7792 23 High Performance Models53 Harry Higley & Sons160 Historic Aviation17 Hobby Barn139 Hobby Horn22 Hobby Lobby International . 169 Hobby Radio NC171 Hobby Woods99 Bob Holman Plans172 1MM154 Indy RC Sales Inc148-150 Larry Jolly Model Products . 172 Jomar20 JTec161 K&B Mfg166 KD Graphics45 K&S Engineering40 K W Enterprises171 Kingsway Enterprises171 Kirks Sportsworld11 Kraft Midwest174 Kustom 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Coy 2&3 1 Mutchlers Hobbies144-145 NF Video Library Navillus Industries Nor-Ray Products Inc . Northeast Aerodynamics Northeast Screen Graphics .. 45 99 37 . 158 . 166 Pacer Tech179 Parrish Aircraft160 Peck-Polymers152 Pelican Enterprises160 Penn International Chem176 Pica Products15 Polks Hobby84 Progress Mfg Co151 Pro-Tune Corp176 RC Buyers Guide22 RC Extras157 RC Soaring Digest158 Radio South140 Red Max Fuel5 SR Batteries143 Safety Plus20 99 Satellite City30-31 Scale Model Research172 Scale Plans & Photo Ser171 Scande Research152 Schlueter Helicopters89 Sermos RC Snap Conn152 Shamrock Comp Imports .. 154 Sheldons Hobby Shop20 Sig Mfg Co18-19161 Sky Baby171 Skyline Hobby Mfg37 Bob Smith Industries47 53 Spirit Lake Hobbies16 Square Cut Tools138 StarBase Exchange167 Star Kraft160 Sullivan Products90-91 Sunshine Hobbies146 Suretech49171 T&D Fiberglass Spec142 Tatone Products Co92 Top Flite Models Inc93 Tower Hobbies6-7 Tru-Turn175 WE Technical Services8 WW Aeroplanes156 Wandit Mfg167 Williams Brothers47 Wilshire Model Center152 Windsor Propeller Co171 Wing Mfg Co166 World EnginesCover 4 YSFutaba159 Yale Hobby Mfg Inc157 Zim pro Marketing177 ers Spiral stability degraded air plane slowed design may have plenty stability buzzing around high speed may tend roll slowed landing approach plane spirally stable speeds must stable its slowest speed Summary conclusions Typical Sail plane models exhibit substantial yaw angles during circling flight circling airspeed variation over wing generates moment causes plane tend roll Dihedral air planes oppose yawing outside circle steady-state circle rolling-in moment balanced rolling out moment caused dihedral out board yaw angle rolling-in moment can accurately calculated moderate angles bank rolling-in moment proportional wing178 Model Aviation No 598 Coronet 150$850 RC-Assist O-T enlarged 1 500k spans 72 uses 40-sizefour-stroke engine SAM-legal 30 two-stroke engine No 599 Kansas Wakefield$475 FF O-T Rubber competitor spans 48 Both 1938/1939 versions No 600 deHavilland Rapide $575 CL Sport Scale biplane spans 351/2 uses two /2A engines No 193StIletto CL Stunt madel McOnnah winner 1976 1960 1982 FAI World Clumps$375 No 239Blue Birds RU Ken Willards fonnation plane 4-channel 16/15 power$375 No 282Crashmeeter CL Crash-punt trainer Iwo oizes1530 36/40 powerS125 No 3101930 Fleet Biplane RU Sport Scale 36140 4-channel Wingapan 56 scale Two sheetsS625 No 314Drake II RC Ken Wilards flyIng boat 3-channel 15-power Pp land umenable gearS375 No 326Taylor Cub RU Don SojIls Schoehiard-Scafo 0495 2-3 choannl Spans 50 inS350 No 332Zephyr RU Smati 2-channel ofider hand-leanch tow themtit slaps anaring S200 No 386Laaer 200 RU Sport Scale mptca champlonahip Aembatic 0w Uses 40 power 4-5 channel Two sheets$1075 No 414ElectrIc Sparley RU Elechic fon flier 00 motOr 3-channel RU o scaled-op 1939 ubber-pewer tanonteS850 No 440Csvellea- RU OkI-limor-tike now design has huge wing slew easy flights 36 por 3 ch Two sheets$1725 No 447112A Miss America RU Old-Toner Texaco modal 049 gfow 2-channets. No 454Sweet P30 FF Neat stick-and-tiune Outdoor Ruhher P-3D-class model contest-winner$296 No 457Spectra RU Eieclnc-power 05-san motor ama 3 dfifeunt wings oport asaring aembatics S700 No 4604-40 RU Sheelder-wing sport flier 4-cycle 43-size esgine 4 chaonels S696 No 465Blue Max II RU Fan-fly sportster 40-size enmo spans 52 Lightwieght stuctaw S700 No 475Buttercup RU Cute eRn sporfoter sees micu 2-ch RU puise-udder Spans 27 0201935 powerS300 No 490Weekender RU Low-wing sport fler 20-aloe 4-st uke eoglae opana 47 inS575 No 506Playmate RU Sport flier 3 RU channeis 16/25-olin engimo spans 50 inS650 No 512Extra 230 RU Olest Scale aceehatic plane spans 8 ft ama Onadra engine Two plan sheetsS1650 No 514Henry T RU Sporfoler 2-3 channel RU spans 52 ii has adiestable wing flaps S475 No 521Comet Jr Clipper Plus 35% RU Oki-limor oportster enne 2-cb RU spans 40 in$650 No 522Sorts PiOus RU Rewmder-ocale laps 40/60 engines spans 43 Two plan sheetsS1050 No 525HI-Tech 2002 RU Canard ducted-lan 45 engimo spmo 36 Two sheetsS1000 No 528Swallow RU Lightweighl hotdugger 40-size foor-otmke engima spans 96 0$025 No 531TerrIble Coupe FE Robber-powered Coups dlriieer spans 40 contest-winnerS475 No 533Cessna C-37 RU Schoolyard Scale fomoas 300 plane 009110 power 2-ch spans 42 inS596 No 5341935 Challenger RU Tenaca OKI-Timor spans 47 040 engine 2-channel RUS550 No 535Atrix RU MSIA Ulmo 0 Sailplane spans 110 ama 4-channel RU system 25 No 539SImilar SlowMotlon 15 RU Taillees flying wing 15 engima spans 00 uses 3-oh RUS350 No 541Parakeet RU Sport leplane 19125 engines 3-channel RU equipment spans 42 inS675 No 544Heron RU Sf Winters sport Electric geared 075 motor 3 RU ch spans 65 inS575 No 549Cricket RU Sport scaleika br 20-size two- four-stinks engine spans 40 inS675 No 554Super Doubler II RU Spert Aeuhaons4ylon 49146 four-stinks engine spano 57 in5576 No 555Double Duly RU Basic/advanced trainer 19115 engima spans either 67 50 Two plan sheetsS1075 No 559Low Voltage RU Elechic-power sportoter 035 motor spans 44 S475 No 553to RU AMA Class B 2-Meter Safiplane has 78W-in-span foam wingS725 No 565Avro 550 FE Mini-electric Scale 23 British utimlight spans 30 in$200 No 569Electroatreak RU Electric aembetic plane spano 44 moo 05 motorS550 No 570Busy Bee FE Pee Wee-30 plane 02 power spans 30 has euher sheet-hales sr haiti-op surfaces$400 No 572TR-260 RU Sport Scale Aumlotic plane 4-otmkn 60/65 power spans 96 in$1100 No 575Scorplon 60 RU Ken-fly sembatic plane 60 power spans 96 in51150 No 576Serendipltyl FE Indoor 028 mcard-holder spans 1775 5325 No 578Schwelzer 1-ZOB RU Ounster-scale Sailplane spans 125 Two plan sheets$1475 No 579Lockheed P35 CL Precislen Scale WiN II figleer twin 45s spans 65 Fonder flaps etc Thmo plan sheets 51800 No 580Pamall Pixie FE Rubber Scale GuIdes Age British biplane 112 scale spans 31 in5375 No581Gee Bee Model Y RU Golden Age Rnner spans 72 ix scale 00 power plan sheetsS1175 No 553Sportwegon RU Radio-fred sport FE model spans 54 ama 19115 engine$796 No 584Happy Days CL Intensedlete trainer/Stuoter opano 42 uses 25136 engine5575 No 555Dragonfly FE fligh-perfonsanca P-30 Rubber ship spans 30 weighs 50 gumsS496 No 556Snapdragon RU Fun-fly/sportster 29130 engimo opons 45 inS696 No 557PlIatius PC-9 CL Futile Scale/Stotter/sportster spans 96 ama 25/36 engine5550 No 585Merlsh RU Slope-Searing SailpImo spans 41 uses 2 RU chasseis5425 No 559Vlckera Wellewley RU Sport Scale WW II hamber spans 89 0 ama 40 4-cycln eagle Two plan sheets ne dxc$1250 No 590Bud Lke Laser Stunter CL Stonter scalelike spans 63 io uses 60 esgine Two plan sheets$1050 No 591Focke-Wulfi FW 190-A RU Sport Scale WW II fighter spmo 96 snax 35/45 2-stroke engine Two plan nht doc$1350 No 592ET CL trainar/sportster oma 00 electric power 6-cat battery pack Wingspan 24 in$475 No 593Taylorcraflt RU Spoil Scale lightplane hafids standard 2-placar clipped-wing air show stuntnr Spans either 7tPb 58 30/40 two-stroke 40140 four-stonke engine Two plan sheets no dacurrwntatlunS1000 No 554P-Si Black Widow UL Pufile Scale tiWil II twin-engine night tighter sma 19125 engine spans 49 inS800 No 595Sparrow RU Sportoter 25 engines spuos 43 inS650 No 596Tomahawk II CL Pufile Stonter ama 36 engine spnns 40 inS500 No 597Handley Page W8b FE Sulls mini-Electric twin-motor biplane spano 30 in$300 Circle numbers plans wish order 193 414 490 531 554 575 585 593 239 440 506 533 555 576 586 594 262 447 512 534 559 578 587 595 310 454 514 535 563 579 588 596 314 457 521 539 568 580 589 597 326 460 522 541 569 581 590 598 332 465 525 544 570 583 591 599 386 478 528 549 572 584 592 600 Plan pnce includes first Class postage US delivery Which Air Mail over 300 miles orders non-US address learn add $251 Air Mail osta e liandlin Ian Make check money order payable US funds drawn US bank Model Aviation c/a AMA 1810 Samuel Morse Dr Reston VA 22090 Please allow 3 6 Weeks delivery Please print carefullyEnclosed $ ______________________ NAME STREET CITY STATE ZIP AMA No ______________ span weight 1/circle radius opposing moment due yaw can also calculated described Part proportional span area airspeed2 yaw angle Equivalent Dihedral Angle yaw angle required achieve steady-state circle may calculated As suming moderate bank angles yaw gle function bank angle propor tional 1/area span weight 1/airspeed2 1/EDA 1/circle radius Baseline aircraft yaw angles presented enable estimation yaw angles other model aircraft Differences behavior different dihe dral types described V-dihedral wings may circled slowly parabolic polyhedral types Also V-dihedral wings have less tendency tip-stall Spiral stability described dis cussed Spiral stability may increased increasing dihedral lengthening vertical tail moment arm reducing area vertical stabilizer method approximately assess spiral stability presented Adequate spiral stability essential achieving maximum circling performance order plane spirally stable speeds must spirally stable its lowest speed Correction If difficulty following some Part 2 Dihedral article September 1988 issue its no small won der block type accidentally mispositioned Readers would like able follow proper continuity should note following Five colunm inches text page 174 starting second line second paragraph under Prototypical dihedral arrangements ending 12th line page 175 should read following text page 176 page 178 Also reference Figure 2 first line third full paragraph page 175 -should have Figure 6 regret errors Letters Editor Continued page 10 fore consider gliding fans very fortu nate have talents knowledge Byron Blakeslee appearing issue articles best What added bonus allow him sub mit find room print two gliding articles sometimes Last year again May 1988 issue super bonus four gliding articles excellent color photos dont know other model magazine produces such good quality both technically artisti cally Please accept congratulations Need less say will continue look forward months issue AB Steve Stevens Nanaimo BC Canada 180 Model Aviation 6 03 0 ciJ cJ 2~ toe -es 04 93 6c zo 0 93 C 0 V 9301 anea 0 0 0 5 Con lOon ae .to od os C 0 -SE 9363 C 4350 tuC tO 55 93 93 93 C 0 0

NO OCR TEXT NO OCR TEXT plane circles tighter banks up air speed increases Increased bank angle re duces span airplane relative circle axis thus reducing rolling-in mo ment increased speed also affects other things however analysis limited bank angles less about 300 fair approximation say no effects due bank angles effect high bank angles may seen tailing-off lines envelope Figure 3 bank angle effect lines would simply overlap Assuming bank angle limitation con sider variables independently wing area wingspan weight lift coefficient air speed yaw angle Equivalent Dihedral An gle circle radius bank angle con sider independently means vary variable time holding other var iables constant changing variable normally affects some oth ers turns out rolling-in moment due circling affected wing span weight circle radius mo ment proportional wing span2 weight l/circle radius fading fast hang get some meaty stuff shortly Reviewing quickly Part Two series rolling-out moment due yaw proportional wingspan wing area air speed2 yaw angle EDA compare sensitivity van ables rolling-in moment rolling-out moment can deduce fol lowing Yaw angle function bank gle steady-state circle proportional 1/wing area wingspan weight lIair speed2 l/EDA l/circle radius relationships will allow esti mate yaw airplane based charts explained below Examples will follow yaw angle plots Figures 3 4 show yaw angle required hold plane steady-state circle Figure 3 plots yaw angle function circle radius Figure 4 plots yaw angle function bank gle plots take account much complexity problem including effect bank angle increased speed bank angle effect ignored however en tire airplane has same sink rate wing has variable airspeed means inboard wing sees higher angle tack related inverse glide ra tio calculation typical Glider showed effect minor also complicates analysis immensely effect ignored plots show yaw single air plane flown variety weights speeds constant lift coefficient has 100 span 1000 sq area l0 EDA weights ranging about two seven pounds values especially lighter three airplanes typical sport RC Sailplanes Looking Figure 4 20 ftIsec 104 Model Aviation ADove rn-low curvajure maae VISIDICI As plane circles airatream passes over out board wing faster inboard wing tends make plane roll same time though vertical stabilizer tends align itself local flow means wing yaws outboard tends make plane roll out get variables right plane will circle stable fashion Below Low-dihedral aileron sailpianes have problem achieving spiral stability vertical stabilizer yaws airplane outboard insufficient dihedral produce net rollout moment especially true large lightweight aileron ships such 1 20-in-span Tango As resuit pilot must circle actively controlling rolling-in tendency top aileron Also tendency pilot increase circling airspeed well beyond optimum Improve spiral stability 03 025 02 LIFT Ib/005 span 015 01 005 -1 -08 -06 -04 -02 0 02 04 06 08 1 V-Dihedral - - APYal -Parabolic ML CL right tip WING STATION fraction semispan 0 -08 -06 -04 -02 0 02 left tipCL Figure 2 0406 08 right tip WING STATION fraction semispan Figure 1 Circling yawing shifts lift distribution outboard rolls plane inboard heavy line plotted represents lift distribution elliptical planform wing circling 30 bank angle fine line beneath lift distribution same wing level flight Extra lift due banking reflected greater average lift heavy line particular plot represents unyawed 100-Inspan 3-lb airplane 30 bank left circle Its level flight speed 20 ft/sec its speed bit higher create extra lift re quired bank angle Figure 2 Yawing outboard redistributes lift distribution Inboard balancing rolling-in moment Note lift distribution parabolic dihedral wing thin line almost symmetrical whereas V dihedral wing heavy line really loads up inboard left wing unloading left tip plot represents same airplane Figure 1 except now yawed outboard 870 model see has yaw some nine degrees circling 300 bank serious yaw Full-size airplanes use sideslip yaw dive brake us ing thermaling Now look what hap pens plane extreme floater fly ing 15 ftIsee 3O bank has yaw nearly 170 Talk about extra drag Calculating yaw angle Suppose have airplane has wing area in2 span weight b airspeed t/sec EDA ight typical FAT F3B-class Sailplane much would yaw com pared 30 ft/sec aircraft Figure 4 First ratio variables area /1000 span 100 weight 438 airspeed 0 EDA must also ratio circle radius proportional airspeed2 circle radius 2 above discussion know yaw must proportional 1/area span weight 1/airspeed2 1/EDA 1/cir cle radius Chaining variable ratios gether relative yaw must 1/110 x 120 x 0874 x 1/09332 x 1/050 x 1/0870 Going Figure 4 find 30 ft/sec airplane must yaw about 43 de grees new plane must yaw 252 x 43 degrees means typi cal F3B Sailplane must yaw outboard about 11 degrees circling 30-degree bank ailerons used hold up wing Since F3B Sailplanes have 30 dihedral clear effi cient thermaling top aileron must used actively pilot hold up inboard wing What have A-2 Nordic Glider cir cling 50-foot radiushow much must yaw Typical vital statistics wing area in2 span eight b airspeed t/sec EDA om pared 15 ft/sec airplane Figure 3 variable ratios would area 475/1000 span 00 weight 859 airspeed 5 EDA compute relative yaw ratios proportioned multiplied together Rela tive yaw 75 x 080 x 0484 x 1/09332 x 1/070 Figure 3 20 175 15 125 Yaw Angle 10 degrees 75 5 25 0 VolSft/sectJI VLI[i]iii J 175r j-.-I-J- 1 20 30 LU 175 15 II 125 Yaw Angie degrees 75 5 25 0 0 l0 203040 50 60 70 80 go 100 Figure 3Circle Radius feetFigure 4 Figure 3 Slower airplanes must yaw outboard lot plot shows yaw angle required circle steadily single airplane flown constant lift coefficient 10 variety weights Note yaw angle plotted against circle radius required yaw indepen dent weight until moderate bank angles reached example wingspan 100 wing area 1000 sq Equivalent Dihedral Angle 10g Vo speed airplane straight flight bank angle increases airspeed increases well weights different speeds slowest fastest 1659 lb 2531 lb 3306 lb 5165 lb 7438 lb Figure 4 As function bank angle slower airplanes must yaw much faster airplanes plot same airplanes shown Figure 3 except yaw angles plotted against bank angle instead circle radius Note maximum yaw angle reached bank angle 450 Beyond 450 wing becomes vertical difference airspeed over entire span diminishes very rapidly point Vo 5 75 20 25 30 6O 55 50 45 40 35 30 25 20 15 10 Dank Angle degrees October 1988 105 025 02 015 LIFT 1b/005 span 01 005 0 left tip Figure 1 find baseline 15 ft/sec airplane yaws about 600 circle radius 50 ft Nordic Glider must yaw 134 x 60 8030 Some Nordics use device creases angle attack inboard wing after tow release order hold up inboard wing much would wing above model have ro tated order eliminate required yaw Part series can calculate 8030 yaw wing 70 EDA gives 0980 change angle tack both wings achieve change wing must piv ot twice much about 200 General examples Now may clear can get yaw information baseline aircraft useful informa tion airplane Rather go through process plane range planes might consider ing following relationships may some use Again based sumption bank angle less 300 have same plane same lift coefficient different weights taken function circle radius yaw angle constant illustrated Figure 3 have same plane same lift coefficient different weights taken function bank angle yaw angle proportional 1/weight illustrated Figure 4 airplane proportionally scaled keeping wing loading same yaw angle function bank angle propor tional scale factor wing area weight kept con stant wingspan varied yaw gle function bank angle propor tional span span wing loading kept constant wing area varied yaw angle function bank angle con stant aspect ratio has no effect yaw angle span wing loading unchanged airplane kept same Equivalent Dihedral Angle varied yaw angle proportional 1/EDA span weight airspeed con stant wing area varied choosing between low high camber wing say yaw angle function bank angle proportional l/wing area High lift high aspect ratio wings yaw low camber low aspect ratio wings exact same airplane flown dif ferent airspeeds lift coefficients taken function circle radius yaw angle varies 1/airspeed2 Speeding up airplane really reduces amount yaw required exact same airplane flown dif ferent airspeed lift coefficient taken function bank angle yaw gle varies 1/airspeed4 As function bank angle yaw angle super sensitive airspeed Dihedral types three prototypical dihe dral types described briefly above de tail Part Two display some important dif ferences behavior circling Simply put V-dihedral wings have less tendency tip-stall polyhedral parabolic wings can flown lower speeds thermaling As planes circle planes yaw out board V-dihedral wing has same angle attack everywhere wing higher inboard wing less out board wing polyhedral wing has highest angle attack inboard tip progressing lowest outboard tip parabolically curved wing has smooth gradation angle attackhighest inboard tip lowest outboard tip Since dihedral angle tip panel polyhedral wing greater V dihedral wings dihedral angle inboard polyhedral tip panel greater angle attack inboard tip parabolic wing greater angle attack poses problem circling Nor mally models thennal near maximum lift coefficient close stall part wing gle attack will stall first limits minimum thermaling speed plane angle attack polyhedral wing greatest inboard tip panel panel limits maximum average lift coef ficient plane circling Like wise very tip parabolic wing lini its its average lift coefficient V dihedral wing limited entire board wing Since spread between maximum angle attack average angle attack least V-dihedral wings able fly slowest circling Parabolic wings have spread must circle fastest avoid stalling inboard tip advantage minor typical middle-weight mid-size RC Sailplanes Let us take example 20 ft/sec air plane Figure 4 300 bank angle also typical must yaw 960 informa tion presented Part can calculate V-dihedral inboard wing must have angle attack 1680 higher av erage angle attack polyhedral wing has tip panels 130 dihedral its inboard tip panel must have angle attack 220 higher average parabolic wing has its tips about 160 dihedral its inboard tip has angle attack about 270 higher average Continued page 175 r5 11 IIIII iilLj II IA J 5101520 Equivalent Dihedral Angle degrees 20 15 Yaw Angle 10 degrees S 0 IIIIII i1II1 III 0255075100125150175 Span inches 200 2530 Figure 6 FIgure 5 Yaw angle circle Inversely proportIonal Equivalent Dihedral Angle plot shows required yaw angle 20 ttIsec airplane used FIgures 3 4 bank angle 300 Major improvements can yaw angle Increasing dihedral say 5 10g less gain increasing tram say 20 250 Figure 6 nature bigger airplanes must yaw order remain stable theyre circling plot shows required yaw angle function wingspan 20 ft/sec airplane 100 Equivalent Dihedral Angle banked up 300 flying lift coefficient 10 Note required yaw angle proportional models wingspan 106 Model Aviation 20 18 16 14 12 Yaw Angle 10 degrees 8 6 4 2 0 Figure 5 Finally heartfelt salute order beautiful people gave selves make 1988 FAC possible successful addition Maxecuter ganizers special thanks Lin Juanita Reichel Tom Schmitt Bob Clemens Ma rie Rees Connie McSulskis Marian Mann Kathy Thomas Peg Paisley Shirley Kuenz Rich Hensel Pat Jupiter Gerry Helen Paisley Otto Kuhni Claude Powell Paul Spreiregen Western NY FF Society Geneseo National Warplane Museum Peck-Polymers Golden Age Reproduc tions Sea Glen Models Blue Swallow Mod els Flyline Models Flying Scale Inc well unsung volunteer timers go-fers helpers especially en thusiastic thanks superb contes tants willingly shared yourselves keep Free Flight Scale alive well growing Bladder/Weinreich Continued page 99 lines shorter reaction time re quired about same bigger contest models Phil Granderson Portland OR came fourth year has won contest twice before practiced playing video games air hockey also flew plane night training himself con trol model depending sight helps him concentrate opposi tion match Just important practice con struction models proper modifica tion engines wings con structed Styrofoam reinforced bal sa carbon fiber fiberglass strapping tape Stabs built lightness tail booms either built-up ones made carbon fiber arrow shafts Models have wingspans about 4 ft weigh 18 20 oz About half weight accounted engine engine mounts Like other Bladder Grabber partici pants Kott designs own planes re works engines putting brass cylinder liners aluminum pistons modi1ing crankshafts Most engines contest started out life Fox 35s Combat has come long way past 20 years Bob Carver remarked Com paring Combat plane 20 years ago today like comparing Model T new Porsche Carver has fly ing 25 years explained speeds have gone 80 120 mph engine power has risen one-half horsepower two Aerodynamics have changed airfoil shapes different moments better planes can turn tighter accelerate faster performance has improved reminded us has skill level pi lots' Ironically last years Nats winner Mark Smith Ft Worth TX found hes im proved models too much built new planes year quicker faster old ones used did fly well Smith rue fully explained Though didnt place years Bladder Grabber hes no quitter planning return next years Theres something about Combat flying just gets blood Bob Carver continues compete de spite never having won Bladder Grabber although year placed respectable seventh summed up way Its ultimate video game Its flier against another its strategy maneu vering evasion attack Its things actual fighter pilots have Ill give Bob last word too know youve alive says after youve flown Combat match As motto Combat observation would hard improve upon Dihedral/Beron-Rawdon Continued page 106 half-degree penalty polyhedral wing relative V-dihedral wing will force increase speed about 3% degree penalty parabolic wing rel ative V-wing will force 55% increase speed Because dihedral angle yaw angle reciprocal works out changing Equlvalent Dihedral Angle has no effect variations angle attack larger slower planes penalty severe Take 120-in-span 1000in2 25-lb plane thermals 175 ft/sec instance plane must yaw 150 300 bank angle V-dihedral plane will thermal 4% slower poly hedral plane 8% slower para bolic wing addition penalty imposed poly hedral parabolic wings steady-state circle another penalty imposed maneu vering circling particular initiat ing roll-out steady-state circle further loads up inboard panel tip loads up polyhedral parabolic wings order leave equal maneuvering margin top existing stall margin polyhedral parabolic wings must flown faster yet V-dihedral wing conclusion draw V-dihedral wings superior ther maling maneuvering thermaling contrast conclusion par abolic polyhedral wings superior steady-state rolling maneuvers mar gin superiority both cases very great important large slow airplanes Spiral stability Spiral stability refers ability airplane roll out cir cle rudder neutralized hold constant circle radius rud der held deflected plane very spirally stable will roll out circle quickly rudder centered will require substantial rudder deflection hold circle will fly straight still PRECISION MODEL PRODUCTS Made U S BARSTOCK ALUMINUM SPINNERS Pan NoSize fl-150B .. 1-1/2 TT-175B .. 1-314 TT-200-B TT-225-B .. 21/4 TT-226-B .. 2114 FAI 11-250-B .. 21/2 TT-251B . 21/2 FAI .. TI-275-B .. 23/4 TI276-B .. 23/4 FAt .. 11-300-B 11301-BFAIl 11325-B .. 3-1/4 l1-350B 3-1/2 11-375-B33/4. 11-400-B4 RetailApprox PriceWeight $1395058 02 149509502 1595100oz 169516002 189515002 189519002 2095170oz 229522002 249520002 269526002 289525002 3695340oz 4995470oz 599552002 6995570oz 3 Pieces Cone Back Plate Retainer Screw Note 3 4 Blade Spinners Available Sizes Add $300 Per Spinner PROP NUT ADAPTORS Pan No Size 11-140-A 28 11-147-A -28/7mm 11-610-A 10mm 11-710-A x 10mm 11-516-A 6-24 11-518-A . 5/16-24/8mm 11-810-A . Ox 10mm 11-825-AOx 125mm 11-375-A3/8-24 11-125-A10 x 125mm RetailApprox PriceWeight $495061 02 495 . 061 oz 495 . 063oz 495OB2oz 49507602 495 .076 02 495076oz 495075 02 595 .ll7oz 595 02 3 Pieces Nut Washer Machined Bushing Add $350 Shipping Handling Prices subject change notice ROMCO MFG INC OX 836 SOUTH HOUSTON TEXAS 77587 713 943-1867 October 1988 175 PlC Video Tape Vol 1 Basics 115 minutes total running time graat ducatLonal ualuc menckd clubs hobbj jJ$$YJkz\shop owners. Model AvIation Nov 1987 Only $1795 tax & shipping mci VISA M/C orders call 415 967-5134 Penn International Chemicals 943 Steirlin Rd Mt View CA 3 4 66 6666 666 6666666666666666666666666666666w 6 DUAL STRUT NICKEL PLATED NOSE GEAR iiiI I suIts Tooling P0 Box 95 ChampaIgn IL 61820 air indefinitely plane neutrally stable will remain circle con trols neutralized no rudder deflec tion required hold turn spi rally unstable airplane will circle tighter steeper controls neutral ized opposite rudder continudus ad justments required hold turn spirally unstable airplane will fly straight its ownit will gradually bank circle spiral down steepness tightness spiral determined degree spiral instability Free Flight models obviously must spirally stable ones arent will crash have limited experience Free Flights seems generous measure spiral stability would vir tue Nevertheless have seen successful models notably FM Power models appeared marginal respect have experience RC Sailplanes 1 am certain what exacfly best have flown spirally unstable air planes definitely unpleasant always try get away very difficult fly precisely other hand Sailplanes excess spiral stability require lot control input cir cle can give plane dull doggy feel may mask feel thermal present preference plane small-to-moderate amount spiral stability Once circle established such plane control input goes making adjustments seems easier sense thermal have seen circling airplane must yaw outboard certain amount avoid rolling spirally stable airplane will naturally yaw outboard amount two basic effects cause outboard yaw first due circular flight path plane second due variable airspeed over wing As plane circles its flight path streamlines curved Since vertical stabilizer aft wing sees dif ferent yaw angle wing vertical stabilizer approximately aligns itself flow airplane wing yaws out board effect illustrated pictures curvature flow can result remarkably large angles example imagine plane 25-ft-radius circle perimeter circle 157 ft distance between wing vertical stabi lizer three feet angle air flow between wing vertical stab approximately 3/157 x 3600 Thus absence other effects vertical stabilizer would align itself local flow airplane would yaw out board 690 Just un-yawed circling wing makes lift outboard panel also makes drag variation drag causes outboard yawing moment opposed lift vertical stabi lizer Lift vertical stabilizer gener ated yawing further outboard its neu tral zero lift angle principal variables spiral stability emerge natural yaw gle plane due its circular path de pends distance between wing vertical stabilizer circle ra dius yaw angle due variation wing drag depends degree varia tion drag turn depends circle radius wing section other fac tors size aspect ratio mo ment arm vertical stabilizer size moment arm vertical stabilizer characterized vertical tail volume quantified vertical tail area wing area x vertical tail moment arm wingspan aspect ratio vertical stabilizer also important since lift curve slope quite sensitive changes aspect ratio aspect ratio low Now see what makes plane yaw outboard other key piece Equiv alent Dihedral Angle Increasing dihe dral reduces amount plane must yaw avoid rolling achieve neutral spiral stability natural yaw angle plane assumes circling must equal angle required balance roll axis adjust spiral stability can either change angle plane natu rally yaws outboard can change angle plane must yaw avoid rolling BATT- CHEKBX Saves Time . Saves Models Install RC Models 3-Level indication receiver battery status press button Precise Rugged Small Light 1/2 oz Made USA Also custom units other applications Order Today $1495 dealer send check money order postpaid Protune Corp 914 4626452 PO Box iaos Poughkeopsle NY 12601 NY State residents add asles tax 176 Model Aviation I C C4 C4 H H H H H H H H H H H H H ... Control Line Products Modelers serving Modelers shing Friend ToolsAdiuslahle Rudder turns Control Horns ControlLines 4 HeansiutyleltcranhsHandles AdiustableEeadoutGoides Ctassic Kits Custom Motor Mounts much ouch Aluminum loserts UNSURPASSED AtAtlitGUARANTEED SATISFACTION Send same address $AAA receive now espanded catalog will get $2 AK otl ynnr first order Craftsman Models Inc 3 Woooie Odm 4u074 dea o oquiries united An example know Figure 3 l00-in-span 20-ft/sec airplane must yaw outboard 96 achieve equilibrium circling 25-ft radius put very large vertical stabilizer 30 ft back wing know above calculation plane will yaw outboard 69 means will roll could lengthen tail moment arm until yaw angles least matched 50-in tail moment arm pretty long l00-in-span Sailplane tail mo ment 30% 40% wingspan typical RC Sailplanes although Free Flights tend longer Another solution would increase dihedral angle 100 EDA 96/69 x 10 reasonable solution remember have very large ver tical stabilizer could also leave vertical tail mo ment arm three feet leave EDA 10 shrink vertical stab extra drag outboard wing can yaw plane outboard Exactly what size vertical stab must complex problem because large number variables number unknowns major var iable effect fuselage especially airplanes large long fuselages relative wing general models easier cut try accurately calculate some trade-offs can get spiral stability small vertical stab short moment arm can also get large small vertical stab long moment arm have too little vertical stab too little moment arm though airplane will have Dutch roll problems rhyth mic yaw-roll oscillation air plane looks pilot flying music waltz condition avoid Free Flight models often trimmed near condition however appears improve ability model center thermals itself perhaps because direction plane much affected what happening wing RC Safiplanes small verticals short moment arms will sluggish con trol because small vertical cannot gener ate much lift compound problem has little leverage plane addition such plane will poorly damped making precision flying difficult discussed Part series large vertical stab long moment arm will give RC models powerful control excellent damping disadvantage large surfaces have drag longer tail booms heavier Careful struc tural aerodynamic design can minimize disadvantages own preference toward larger verticals longer tail booms neat feature spiral stability works circle radii set up just stable 25-ft radius will still just stable 50-ft radius because amount plane must yaw pro portional 1/circle radius amount plane does yaw proportional 1/cirdc radius Keep mind depen dent variables some unpredictable dont expect perfection information see can estimate whether design will spi rally stable make effective adjustments have determine yaw gle required configuration de termine much yaw will occur effect flow curvature flow cur vature gives required yaw angle almost guaranteed have spiral stability need some out board yaw know vertical stab will have carefully sized best guess would typical RC Sailplanes can count plane yawing about two three degrees outboard very large vertical stabilizer would al low Some Free Flight Nordic models use very low aspect ratio verticals might allow something order six degrees guess remember Achieving spiral stability aileroncontrolled airplanes can problematic ample vertical stabilizer put reason able distance wing generous amount dihedral required achieve spiral stability turn causes tinwanted roll responses unintended yaw de flections such adverse yaw due aile rons crosswind takeoff perhaps gyroscopic coupling roll pitch axes Reducing size vertical stabi lizer may partially effective going too far can result very loose air plane Lengthening tail boom also helpful has its penalties weight drag An additional facet spiral stability pointed out Dr Andy Bauer described him paper National Free Flight Society Digest 1987 Note above required yaw angle circle given airplane very sensitive airspeed Faster airspeeds require substan tially less yaw angle means air plane may spirally stable low speeds may stable higher speeds Radio Control Free Right Gliders has great importance Free Flight mod els insufficient spiral stability cannot trimmed best glide elevator trimmed slow model optimum speed inadequate spiral stability model starts roll As does however gains speed improved spiral stability same time process begins circling higher less efficient speed model adequate spiral sta bility could have trimmed fly slower entering roll-in speedup cycle same effect occurs RC Sailplanes particularly ailerons low dihedral Such models unstable flying slowly auto matic tendency part pilot speed up thermaling thus degrading performance moral achieve maximum circling performance sure have adequate ample spiral stability effect also important considera tion RC power models especially trainexperience Great Performance Quartet DALOTEL 850 SPAN 69 InsWING AREA 830 sq ins CHIPMUNK 850 SPAN 70 insWING AREA 850 sq ins SPAN 76 SPAN 72 ins IF EXTRA 230 WING AREA 900 sq ins ZLIN 526 WING AREA 900 sq ins series Sport Scale Balsa ARF Airplanes 120-4 cycle equivalent motors See RCHTA Show October 14-16 1988 available direct select hobby shops c ZIMP ROMARKETINO 1 PO BOX 3076 OAK RIDGE TN 37830 PHONE 615-482-6188 October 1988 177 ADVERTISERS INDEX 4-M Company 16 AH Designs51 AMA Employment4 AMA Membership141 AMA Museum170 Ace Radio Control41 Aerodrome Models142 Aero Plans N Parts156 Aerospace Composite Prod Air Champ Models168 Airtronics2 AI-tec Su-pr-Line Prod40 American Sailplane Des171 Astro Flight9 B&P Associates51 Quay Barber Models152 Bell Rock Industries138 Berkeley Trading Co158 Blue Ridge Mach& Tools .. 172 Bolar Heli Research146 Byron Originals80 C&C Electronics53 Campbell Tools Co171 Carlson Engine Imports172 Circus Hobbies162-164 Classic Glass49 Cleveland Model Supply22 Eric Clutton171 Colorado Model Products16 Coverite156 Cox Hobbies94 Craftsman Models 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Northeast Aerodynamics Northeast Screen Graphics .. 45 99 37 . 158 . 166 Pacer Tech179 Parrish Aircraft160 Peck-Polymers152 Pelican Enterprises160 Penn International Chem176 Pica Products15 Polks Hobby84 Progress Mfg Co151 Pro-Tune Corp176 RC Buyers Guide22 RC Extras157 RC Soaring Digest158 Radio South140 Red Max Fuel5 SR Batteries143 Safety Plus20 99 Satellite City30-31 Scale Model Research172 Scale Plans & Photo Ser171 Scande Research152 Schlueter Helicopters89 Sermos RC Snap Conn152 Shamrock Comp Imports .. 154 Sheldons Hobby Shop20 Sig Mfg Co18-19161 Sky Baby171 Skyline Hobby Mfg37 Bob Smith Industries47 53 Spirit Lake Hobbies16 Square Cut Tools138 StarBase Exchange167 Star Kraft160 Sullivan Products90-91 Sunshine Hobbies146 Suretech49171 T&D Fiberglass Spec142 Tatone Products Co92 Top Flite Models Inc93 Tower Hobbies6-7 Tru-Turn175 WE Technical Services8 WW Aeroplanes156 Wandit Mfg167 Williams Brothers47 Wilshire Model Center152 Windsor Propeller Co171 Wing Mfg Co166 World EnginesCover 4 YSFutaba159 Yale Hobby Mfg Inc157 Zim pro Marketing177 ers Spiral stability degraded air plane slowed design may have plenty stability buzzing around high speed may tend roll slowed landing approach plane spirally stable speeds must stable its slowest speed Summary conclusions Typical Sail plane models exhibit substantial yaw angles during circling flight circling airspeed variation over wing generates moment causes plane tend roll Dihedral air planes oppose yawing outside circle steady-state circle rolling-in moment balanced rolling out moment caused dihedral out board yaw angle rolling-in moment can accurately calculated moderate angles bank rolling-in moment proportional wing178 Model Aviation No 598 Coronet 150$850 RC-Assist O-T enlarged 1 500k spans 72 uses 40-sizefour-stroke engine SAM-legal 30 two-stroke engine No 599 Kansas Wakefield$475 FF O-T Rubber competitor spans 48 Both 1938/1939 versions No 600 deHavilland Rapide $575 CL Sport Scale biplane spans 351/2 uses two /2A engines No 193StIletto CL Stunt madel McOnnah winner 1976 1960 1982 FAI World Clumps$375 No 239Blue Birds RU Ken Willards fonnation plane 4-channel 16/15 power$375 No 282Crashmeeter CL Crash-punt trainer Iwo oizes1530 36/40 powerS125 No 3101930 Fleet Biplane RU Sport Scale 36140 4-channel Wingapan 56 scale Two sheetsS625 No 314Drake II RC Ken Wilards flyIng boat 3-channel 15-power Pp land umenable gearS375 No 326Taylor Cub RU Don SojIls Schoehiard-Scafo 0495 2-3 choannl Spans 50 inS350 No 332Zephyr RU Smati 2-channel ofider hand-leanch tow themtit slaps anaring S200 No 386Laaer 200 RU Sport Scale mptca champlonahip Aembatic 0w Uses 40 power 4-5 channel Two sheets$1075 No 414ElectrIc Sparley RU Elechic fon flier 00 motOr 3-channel RU o scaled-op 1939 ubber-pewer tanonteS850 No 440Csvellea- RU OkI-limor-tike now design has huge wing slew easy flights 36 por 3 ch Two sheets$1725 No 447112A Miss America RU Old-Toner Texaco modal 049 gfow 2-channets. No 454Sweet P30 FF Neat stick-and-tiune Outdoor Ruhher P-3D-class model contest-winner$296 No 457Spectra RU Eieclnc-power 05-san motor ama 3 dfifeunt wings oport asaring aembatics S700 No 4604-40 RU Sheelder-wing sport flier 4-cycle 43-size esgine 4 chaonels S696 No 465Blue Max II RU Fan-fly sportster 40-size enmo spans 52 Lightwieght stuctaw S700 No 475Buttercup RU Cute eRn sporfoter sees micu 2-ch RU puise-udder Spans 27 0201935 powerS300 No 490Weekender RU Low-wing sport fler 20-aloe 4-st uke eoglae opana 47 inS575 No 506Playmate RU Sport flier 3 RU channeis 16/25-olin engimo spans 50 inS650 No 512Extra 230 RU Olest Scale aceehatic plane spans 8 ft ama Onadra engine Two plan sheetsS1650 No 514Henry T RU Sporfoler 2-3 channel RU spans 52 ii has adiestable wing flaps S475 No 521Comet Jr Clipper Plus 35% RU Oki-limor oportster enne 2-cb RU spans 40 in$650 No 522Sorts PiOus RU Rewmder-ocale laps 40/60 engines spans 43 Two plan sheetsS1050 No 525HI-Tech 2002 RU Canard ducted-lan 45 engimo spmo 36 Two sheetsS1000 No 528Swallow RU Lightweighl hotdugger 40-size foor-otmke engima spans 96 0$025 No 531TerrIble Coupe FE Robber-powered Coups dlriieer spans 40 contest-winnerS475 No 533Cessna C-37 RU Schoolyard Scale fomoas 300 plane 009110 power 2-ch spans 42 inS596 No 5341935 Challenger RU Tenaca OKI-Timor spans 47 040 engine 2-channel RUS550 No 535Atrix RU MSIA Ulmo 0 Sailplane spans 110 ama 4-channel RU system 25 No 539SImilar SlowMotlon 15 RU Taillees flying wing 15 engima spans 00 uses 3-oh RUS350 No 541Parakeet RU Sport leplane 19125 engines 3-channel RU equipment spans 42 inS675 No 544Heron RU Sf Winters sport Electric geared 075 motor 3 RU ch spans 65 inS575 No 549Cricket RU Sport scaleika br 20-size two- four-stinks engine spans 40 inS675 No 554Super Doubler II RU Spert Aeuhaons4ylon 49146 four-stinks engine spano 57 in5576 No 555Double Duly RU Basic/advanced trainer 19115 engima spans either 67 50 Two plan sheetsS1075 No 559Low Voltage RU Elechic-power sportoter 035 motor spans 44 S475 No 553to RU AMA Class B 2-Meter Safiplane has 78W-in-span foam wingS725 No 565Avro 550 FE Mini-electric Scale 23 British utimlight spans 30 in$200 No 569Electroatreak RU Electric aembetic plane spano 44 moo 05 motorS550 No 570Busy Bee FE Pee Wee-30 plane 02 power spans 30 has euher sheet-hales sr haiti-op surfaces$400 No 572TR-260 RU Sport Scale Aumlotic plane 4-otmkn 60/65 power spans 96 in$1100 No 575Scorplon 60 RU Ken-fly sembatic plane 60 power spans 96 in51150 No 576Serendipltyl FE Indoor 028 mcard-holder spans 1775 5325 No 578Schwelzer 1-ZOB RU Ounster-scale Sailplane spans 125 Two plan sheets$1475 No 579Lockheed P35 CL Precislen Scale WiN II figleer twin 45s spans 65 Fonder flaps etc Thmo plan sheets 51800 No 580Pamall Pixie FE Rubber Scale GuIdes Age British biplane 112 scale spans 31 in5375 No581Gee Bee Model Y RU Golden Age Rnner spans 72 ix scale 00 power plan sheetsS1175 No 553Sportwegon RU Radio-fred sport FE model spans 54 ama 19115 engine$796 No 584Happy Days CL Intensedlete trainer/Stuoter opano 42 uses 25136 engine5575 No 555Dragonfly FE fligh-perfonsanca P-30 Rubber ship spans 30 weighs 50 gumsS496 No 556Snapdragon RU Fun-fly/sportster 29130 engimo opons 45 inS696 No 557PlIatius PC-9 CL Futile Scale/Stotter/sportster spans 96 ama 25/36 engine5550 No 585Merlsh RU Slope-Searing SailpImo spans 41 uses 2 RU chasseis5425 No 559Vlckera Wellewley RU Sport Scale WW II hamber spans 89 0 ama 40 4-cycln eagle Two plan sheets ne dxc$1250 No 590Bud Lke Laser Stunter CL Stonter scalelike spans 63 io uses 60 esgine Two plan sheets$1050 No 591Focke-Wulfi FW 190-A RU Sport Scale WW II fighter spmo 96 snax 35/45 2-stroke engine Two plan nht doc$1350 No 592ET CL trainar/sportster oma 00 electric power 6-cat battery pack Wingspan 24 in$475 No 593Taylorcraflt RU Spoil Scale lightplane hafids standard 2-placar clipped-wing air show stuntnr Spans either 7tPb 58 30/40 two-stroke 40140 four-stonke engine Two plan sheets no dacurrwntatlunS1000 No 554P-Si Black Widow UL Pufile Scale tiWil II twin-engine night tighter sma 19125 engine spans 49 inS800 No 595Sparrow RU Sportoter 25 engines spuos 43 inS650 No 596Tomahawk II CL Pufile Stonter ama 36 engine spnns 40 inS500 No 597Handley Page W8b FE Sulls mini-Electric twin-motor biplane spano 30 in$300 Circle numbers plans wish order 193 414 490 531 554 575 585 593 239 440 506 533 555 576 586 594 262 447 512 534 559 578 587 595 310 454 514 535 563 579 588 596 314 457 521 539 568 580 589 597 326 460 522 541 569 581 590 598 332 465 525 544 570 583 591 599 386 478 528 549 572 584 592 600 Plan pnce includes first Class postage US delivery Which Air Mail over 300 miles orders non-US address learn add $251 Air Mail osta e liandlin Ian Make check money order payable US funds drawn US bank Model Aviation c/a AMA 1810 Samuel Morse Dr Reston VA 22090 Please allow 3 6 Weeks delivery Please print carefullyEnclosed $ ______________________ NAME STREET CITY STATE ZIP AMA No ______________ span weight 1/circle radius opposing moment due yaw can also calculated described Part proportional span area airspeed2 yaw angle Equivalent Dihedral Angle yaw angle required achieve steady-state circle may calculated As suming moderate bank angles yaw gle function bank angle propor tional 1/area span weight 1/airspeed2 1/EDA 1/circle radius Baseline aircraft yaw angles presented enable estimation yaw angles other model aircraft Differences behavior different dihe dral types described V-dihedral wings may circled slowly parabolic polyhedral types Also V-dihedral wings have less tendency tip-stall Spiral stability described dis cussed Spiral stability may increased increasing dihedral lengthening vertical tail moment arm reducing area vertical stabilizer method approximately assess spiral stability presented Adequate spiral stability essential achieving maximum circling performance order plane spirally stable speeds must spirally stable its lowest speed Correction If difficulty following some Part 2 Dihedral article September 1988 issue its no small won der block type accidentally mispositioned Readers would like able follow proper continuity should note following Five colunm inches text page 174 starting second line second paragraph under Prototypical dihedral arrangements ending 12th line page 175 should read following text page 176 page 178 Also reference Figure 2 first line third full paragraph page 175 -should have Figure 6 regret errors Letters Editor Continued page 10 fore consider gliding fans very fortu nate have talents knowledge Byron Blakeslee appearing issue articles best What added bonus allow him sub mit find room print two gliding articles sometimes Last year again May 1988 issue super bonus four gliding articles excellent color photos dont know other model magazine produces such good quality both technically artisti cally Please accept congratulations Need less say will continue look forward months issue AB Steve Stevens Nanaimo BC Canada 180 Model Aviation 6 03 0 ciJ cJ 2~ toe -es 04 93 6c zo 0 93 C 0 V 9301 anea 0 0 0 5 Con lOon ae .to od os C 0 -SE 9363 C 4350 tuC tO 55 93 93 93 C 0 0