DoWe Really Understand Ou EHHS math involved determining propeller pitch speed per formance incom prehensible us article spells out stepby-step shows can apply understanding props commonly useEJohn Brownlee John Brownlee 52 has built model aircraft since 1940 AC since late 19505 An engineer says interested aero dynamic theory merely out curiosity MPHOBxPitchxRPMx000947 1 THE TITLE article stems fact Eq 1 widely used calculate either required propeller pitch speed model will fly based nominal propeller pitch inflight rpm As pitch equation identifies correct nominal pitch optimum efficiency propellers symmetrical airfoil airfoil used typical model aircraft propeller possesses considerable camber however Eq 1 does contain sufficient information deal fact As result tends overul U z Ml U U IL Ml 08 06 04 02 0 TfffJ PD -_ IA -----1---K---- --y / / / / 0 02 04 V nD 06 Fig 1 Propeller efficiency vs i Clark Y 15 deg pitch angle state required pitch 25-35% used calculate mph Eq 1 justified assumption moving forward speed equal calculated advance nominal pitch line constitutes condition 100% effici ency Actual efficiency assumed about 80% construed serve speed limiter relative nominal pitch line advance hence 08 term Eq 1 Neither assump tions correct however quite possible observe model flying 14 times speed predicted purposes article 1 Develop equation calculating pitch optimum efficiency can accommodate cambered airfoils 2 Analyze efficiency curve propeller Clark-Y airfoil demonstrate optimum efficiency can result propeller moving forward faster calculated pitch line advance speed 3 Develop correct equation calculating level flight speed order point out parameters must known order achieve acceptable accuracy Normally propeller performance power absorption function J-F actor Advance Ratio quantitatively V/nD V forward velocity feet per sec 1467 x mph n propeller revolutions per second rpm/60 D diameter feetd/l 2 observed plane flying 60 mph 08 airfoil Two blades 10-in propeller tuming 12000 rpm J would found follows 1467 x60 v2000lOos28 60 12 consider effective pitch P propeller above example find lOS6xmph 1056x60 528 rpm12000 Since above calculations differ fact diameter considered P follows P D P d P having dimensions assigned diameter feet inches should also noted P has no relationship whatsoever actual propeller pitch will vary restraint imposed forward progress Now assume restraintdrag removed example propeller just enough power applied maintain 12000 rpm propeller would gain speed until reached point no thrust lift could generated efficiency would zero Lets call point Jll wouldbeJ1xd brief glance Fig 1 will show propeller efficiency value reaches maximum some point between J0 J1 Lets call M M would M x d 36 Model Aviation addition changeable effective pitch fixed-pitch propeller must also possess un changeable nominalpitch pitch designation contains information required construct propeller must therefore answer equation calculate pitch efficiency Lets call pitch N- no direct J counterpart N can shown J propeller will moving forward speed equal calculated nominal pitch line advance speed Now lets assume access large number curves like Fig 1 covering propellers various pitch angles number blades airfoils etc careful scrutiny concluded J 1 propeller efficiencies near maximum willing ignore slight deviations could say M0•8 P1 Thisiswheretheterm08 inEq originates coincidence efficiency 80% 08 P1 propellers very low pitch angles 92-93% efficiency will realized may also write P1 M Substitut ing mph target specified rpm gives Ia 1056 xmph P1125x rpm Eq 1 rearranged does result useful answer since N considered Mathematically can divide both sides 1/N changing equation gives 125 lOS6xmph lN rpm 2 Eq 2 cannot solved rationally since ij appears both sides knowing 1/N function amount camber airfoil used solving Eq 1 calling result N assume 1/N 100 practical purposes true symmetrical airfoils Eq 2 can seen 1/N 125 optimum efficiency within limits imposed our08 J1 compro mise will realized propeller moving forward pitch line advance speed 1/N greater 125 optimum effici ency will realized propeller Out running its pitch Moving second purpose lets look Fig 1 detail see what camber Clark Y airfoil does 1/N ratio curve purloined old aerodynamic treatise applicable models because pitch angle 075 R radius range commonly used J1 about 082 diameter 11 inches P1 would about 92 inches N found follows tan pitch angle x 314 x d x r/R 3 x 314 x 11 x 75 1/N 902/694 130 know propeller will running 130/125 104 times fast its nominal pitch line advance 1 0656 P/d 11 063 and0656/063 naturally 104 also can further see 070/063 times nominal pitch line advance speed propeller still converting 80% power required turn thrust 130 correct value Pl/PN use Eq 2 certainly preferrable 100 actual value changes P/d blade thickness ratio 16 x will about 137 9 x 7 will about 125 propellers have blades thinner Clark-Y 116% automatically reduces camber hence Continued page 128 gi chain no stronger its weakest link ting Part neBeam ScrewDrillpower plant model No eWidth SizeSizePriceplane no better engine mount poorly 909605 049-051650#2 x 3/81/16$169installed vibration 909610 0900#2 x 341/16179generating motor mount 909615 5965#4 x 1/23/32189can cause immeasurable 909620 5120#4 x 1/23/32199trouble airborne 909640 35-40-45130#4 x 1/23/32249system aircraft 909660 0156#6 x 3/47/64299Airtrortics engine mounts 90966161 pump170#6 x 3/47/64299makes difference details complete product line send $100 24-page catalog AirtrOnico products see 1~\ FULL ONE YEAR LIMITED WARRANTY ON ALL EL SYSTEMS local hobby shop E ~AEID~ 12190 WOODRUFF AVENUE Well Prepared answer5K ENEEwUUDOWNEr CALIFORNIA 90241 questions provide youTELEPHONE 213 862-6583 assistance wmw wwuwwumww COMPLETE THIS FORM AND ATTACH MAILING LABEL FROM RECENT ISSUE KNOW WHERE YOU ARE GOING move please let us know advancesix weeks re quired change address Attach current MA mailing label check appropriate box mail Subscription Dept. Model Aviation 815 Fifteenth St NW Washington DC. 20005 Check appropriate boxenclose payment 0 NEW SUBSCRIPTION 0 CHANGE OF ADDRESS Non-AMA subscrIptIon rates $1800 12 months US possessIons elsewhere IncludIng Canada MexIco $2400 US Schools $900 US LIbrarIes $1350 NAME ADDRESS CITY/STATE ___________________________________________ ZIP ______________ MODEL AVIATION 815 FIFTEENTH ST. NW. WASHINGTON DC 20005 AVIATION BOOKS AT DISCOUNTS New Group Discount Plan Zenith Aviation Books Discounts 40% off list prices Nearly 1000 titles around World TWO simple requirements 1 A single check covering order 2 One ship-to address Free catalog discount info & details ZENITH AVIATION BOOKS North Branch MN 55056161 2 583-2573 JUST PUBLISHED Available Group Discount I14ERE ARE NO SECRETS Higley Model finishtng techniques horn m tins 314 photos 16 chap tern ton-Or Comtiots Paint Problems Color Paints Sealets Fillets Ponrets Erushes & 6rushjog Fillets & Cunopren Faint Contents & trying etc 03 ygs softbound 21553C$995 July 198237 Hobbi Shack SUPERMARKET OF HOBBY GOODS SUPER DISCOUNTS PRICES GOOD THRU MAY 82 COXTD049or051 $1747 049 NO 553602 051 NO 553610 HOUSE BALSA 2x2 NO 576377 LIST $2495 1567 DEVCON 5-MINUTE EPOXY NO 566281 LIST $999$576 0-MIDWEST SWEETN LOW NO 569053 LIST $5695. 99 FUTABA SAVINGS FP-4L 3 S26 servos -NO711862eaa LIST $19995 FP-7 FG K jfi with 4 S-26 servos NO 712356 $2499 LIST $39995 9 HUNDREDS MORE SUPER VALUES AND INTERESTING MODEL ARTICLES FREE y Shack customers ceive 32 age SPORT FLYER regularly would like copy simply write us ask FUJI 099 R/C NO 120618 LIST $31 95$1799 PMP THERMAL 73 NO 541492 LIST $2995 788 S HOBBY SHACK HEAT GUN NO 110445 LIST $3295 1499 I0 name address city I statezip U mail order catalogs 18480 BANDILIER CIRCLE 1FOUNTAINVALLEYCA9287081 frequency receiver Jack Albrecht AMA Frequency Committee has taken image problems account making draft Phase-In Plan frequency usage plan followed wont able buy systems suffer image problems leaves 7208/7296 problem familiar will go away five years Till know about careful Some folks already have scanners non-RC bands question bound asked Can use scanner RC answer according John Lange Yes proper converter Once again contact John address call sign given early column precise information need Finally direct attention back cheapest solution could come u ctronic Bird-Dog published Radio Technique January 1982 will monitor channel receiver will monitor very well draws about 300mA order heard above noise engines field wouldnt want leave plugged flight pack very long will completely discharge usual 500 mAh pack less two hours intend con tinuousmonitoring Bird-Dog puta 100ohm resistor series loudspeaker should cut current drain down about 35 mA Keep letters flowing George M Miers 70 Froehlich Farm Rd HieksiiIle NY 11801________ SAFE FLYING IS NO ACCIDENT Neighvion/ Randolph Continued page 35 will find can taxi out spot stop apply power takeoff just would larger plane Dont hurry rotate first flight Apply slight back stick let Neighvion fly off Climb straight out level off trim out original required slight up left trim initial flight Landings quite easy Come back power fly pattern ease off power just before touch-down Smooth time Neighvion smooth solid flier Props Brown lee Con ftnued page 37 l/N As shall see later performance will affected critically pitch long diameter correct let engine develop its maximum power computation purposes value 125 suggested Results obtained using Eq 2 will no better mph value used leads purpose number three starting point equilibrium condition available thrust equals total airframe drag engineering terms Power Out tx velocIty4 Efficiency E r In550 x hp 550 x hp x E thereforeTv4a DCDxOOll9xv2xS5 CD airframe drag coefficient based wing area V velocity feet-per-second S wing area square feet 1 28 Model Aviation GOITIOLINI TEND PROFILE0 COMBA RA T WIDE & NARROW WEDGE 15 -- 6 os Capacities UNIFLOW & TINDD Custom 31il lush Ingredients deraited brochure50C stamps/check CAROLINA TAFFINDER 8345 Delhi Road Charleston Hgts SC 29405 h THE NELSON 15. UN4 VES TION4IL Y THE lEST QUARTER MIDGET AMA C PAl PLUS THE TEXAS 3O complete information Write Kus torn Kraftsmanship Brochure PO Box 2699 Laguna Hills CA 92653 Call f7 14 830-5 162 Dealer inquiries invited IN STOCK FOR IMMEDIATE SHIPMENT NewSUPER QUADRA$9995 wth BRISIGHELLA FLYWHEEL$11995 QUADRA REPAIR51000 plot pent KIORITZ engine 244 c in519995 PUW RADIAL ENGINES FleerS2295 Jorr M ester ERCOUPEPLANS S2395 KIT S22995 Jier M TOMAHAWKPLANS $2395 KIT S245 95 BALSA BASSWOOD oil sicen35% OFF Concept FLEETKIT 517995 F 0 CoW $1995 QUADRA foel tonkO16 0 5695 32 oe S795 VICKERSor LEWIS MACHINE GUN KITS51499 10 RED WHEELS USA Pop$2595 PLANS SUPER STEARMAN reyS250O STARDUSTER TOO ghelleS29 95 scale J-3 CUB Nelde$2995 VDLKSPLANE ken ChorIreS2395 FLY BABY $1696 56-5 ch524RR COCKPIT KITS Tocehewk F4U-1 SprtfrreS21 95 Ercoope $1795 Steerroen 52G 95 Creebrie $2495 I-3 Cob 51950 ME-lOS $21 50 Fleet $1995 FIBERGLASS ARROW SHAFTS 5/16 032 1g6/51000 24-Hour Service. Add $250 postage Send Bank Check Money Order JIM MESSERS QUALITY MODEL PRODUCTS 106 Valley View Dr Allegany NY 14706 hpxE Vmph527CD X Eq 6 must know hp propeller absorbingthe effective poweroutput engine approximate efficiency propeller can attain indicated V latter will vary substantially P/D 16 x 4 being capable about 67% maximum 9 x 7 being able reach about 85% maximum CD will vary greatly depending type aircraft involved can low 0025 up probably high 007 5 heavy slow flying biplane flat cowl lots wing struts wires wire-spoked wheels etc S should easy determine point illustrate much detail information needed calculate flight speed accurately Obviously get close multiplying pitch x rpm x efficiency will accident painless type Eq 6 can however used accurately quantify effect changing parameters involved leaving others fixed will close example involving E Lets suppose observed 11 x 694 propeller flight P real good power plant tuming 15000 rpm time J would 08 x 063 0504 actual V would about 115 fps or784 mph Fig 1 can determine F would about 077 Recognizing propeller operating higher-than-optimum angle attack wish change propellers P pitch reduced d must increased preserve hp net effect J will also decrease about 045 Fig will no longer valid since pitch angle will reduced FCC NPRM Continued aqe 40 making proceeding contact Donald Draper Campbell FCC Office Science Tech nology Spectrum Planning Branch Washing ton DC 20554 telephone 202 653-81 77 Federal Communications Commission William J Tricario Secretary Note 1 26 October 17 November 12 De cember 1979 Note 2 end Academy applied experimental license Part 5 19 August 1980 file number 8272-ER-PL-8o operate four 900 MHz frequencies An experimen tal license KK2XFz issued 28 Janu ary 1981 Note 3 26995 27045 27095 27145 27195 27255 MHz latter frequen cy shared other services Note 4 7208 7216 7224 7232 7240 7296 7564 MHz Continued page 132 SERVO GARD SERVO GARD mon bone fhght battery peck voltage well radio signal received transmitter cod reneiver malfunction detected part system SERVO GARO reduces throttle automatically ample time before battery failure safely land model SPECIFICATIONS Size unit installed KPS-14 servo case easy installation Just plug throttle servo output Weight Approx 1 oz Sensitivity Accurate within 02 Volts Servo Pulse Unit shipped positive pulse systems negative pulse available upon request SERVO GARD comes complete pro-wired pigtails servo connectors choice installed specify connector type orderl SEE YOUR DEALER OR ORDER DIRECT DEALER INOUIRIES IN VI TED Price $3795 Postpaid ISpecify connector typo positive negative pulse orderingl ENDORSED BY THE SPIRIT OF AMERICA SHOW TEAM LIMA OHIO R F Enterprises 106 N Main St Arlington OH 45814 419 365-5360 July 1982 129 Equating Eq 4a Eq. 5 solving y new efficiency curve will somewhat givesleft curve Fig 1 E J will beGet install don t take off about080 andthenewVwillbewithout Ken Willard RCM 6x 7841013 x 784 slight further increase V would result reduced slip stream velocity Such small change would justified desire squeeze last drop performance Out power plant engine plus propeller close hoped points have made clearly Take propellers complicated exciting further hoped article will enable respond definite yes answer asked question title
Edition: Model Aviation - 1982/07
Page Numbers: 36, 37, 128, 129
DoWe Really Understand Ou EHHS math involved determining propeller pitch speed per formance incom prehensible us article spells out stepby-step shows can apply understanding props commonly useEJohn Brownlee John Brownlee 52 has built model aircraft since 1940 AC since late 19505 An engineer says interested aero dynamic theory merely out curiosity MPHOBxPitchxRPMx000947 1 THE TITLE article stems fact Eq 1 widely used calculate either required propeller pitch speed model will fly based nominal propeller pitch inflight rpm As pitch equation identifies correct nominal pitch optimum efficiency propellers symmetrical airfoil airfoil used typical model aircraft propeller possesses considerable camber however Eq 1 does contain sufficient information deal fact As result tends overul U z Ml U U IL Ml 08 06 04 02 0 TfffJ PD -_ IA -----1---K---- --y / / / / 0 02 04 V nD 06 Fig 1 Propeller efficiency vs i Clark Y 15 deg pitch angle state required pitch 25-35% used calculate mph Eq 1 justified assumption moving forward speed equal calculated advance nominal pitch line constitutes condition 100% effici ency Actual efficiency assumed about 80% construed serve speed limiter relative nominal pitch line advance hence 08 term Eq 1 Neither assump tions correct however quite possible observe model flying 14 times speed predicted purposes article 1 Develop equation calculating pitch optimum efficiency can accommodate cambered airfoils 2 Analyze efficiency curve propeller Clark-Y airfoil demonstrate optimum efficiency can result propeller moving forward faster calculated pitch line advance speed 3 Develop correct equation calculating level flight speed order point out parameters must known order achieve acceptable accuracy Normally propeller performance power absorption function J-F actor Advance Ratio quantitatively V/nD V forward velocity feet per sec 1467 x mph n propeller revolutions per second rpm/60 D diameter feetd/l 2 observed plane flying 60 mph 08 airfoil Two blades 10-in propeller tuming 12000 rpm J would found follows 1467 x60 v2000lOos28 60 12 consider effective pitch P propeller above example find lOS6xmph 1056x60 528 rpm12000 Since above calculations differ fact diameter considered P follows P D P d P having dimensions assigned diameter feet inches should also noted P has no relationship whatsoever actual propeller pitch will vary restraint imposed forward progress Now assume restraintdrag removed example propeller just enough power applied maintain 12000 rpm propeller would gain speed until reached point no thrust lift could generated efficiency would zero Lets call point Jll wouldbeJ1xd brief glance Fig 1 will show propeller efficiency value reaches maximum some point between J0 J1 Lets call M M would M x d 36 Model Aviation addition changeable effective pitch fixed-pitch propeller must also possess un changeable nominalpitch pitch designation contains information required construct propeller must therefore answer equation calculate pitch efficiency Lets call pitch N- no direct J counterpart N can shown J propeller will moving forward speed equal calculated nominal pitch line advance speed Now lets assume access large number curves like Fig 1 covering propellers various pitch angles number blades airfoils etc careful scrutiny concluded J 1 propeller efficiencies near maximum willing ignore slight deviations could say M0•8 P1 Thisiswheretheterm08 inEq originates coincidence efficiency 80% 08 P1 propellers very low pitch angles 92-93% efficiency will realized may also write P1 M Substitut ing mph target specified rpm gives Ia 1056 xmph P1125x rpm Eq 1 rearranged does result useful answer since N considered Mathematically can divide both sides 1/N changing equation gives 125 lOS6xmph lN rpm 2 Eq 2 cannot solved rationally since ij appears both sides knowing 1/N function amount camber airfoil used solving Eq 1 calling result N assume 1/N 100 practical purposes true symmetrical airfoils Eq 2 can seen 1/N 125 optimum efficiency within limits imposed our08 J1 compro mise will realized propeller moving forward pitch line advance speed 1/N greater 125 optimum effici ency will realized propeller Out running its pitch Moving second purpose lets look Fig 1 detail see what camber Clark Y airfoil does 1/N ratio curve purloined old aerodynamic treatise applicable models because pitch angle 075 R radius range commonly used J1 about 082 diameter 11 inches P1 would about 92 inches N found follows tan pitch angle x 314 x d x r/R 3 x 314 x 11 x 75 1/N 902/694 130 know propeller will running 130/125 104 times fast its nominal pitch line advance 1 0656 P/d 11 063 and0656/063 naturally 104 also can further see 070/063 times nominal pitch line advance speed propeller still converting 80% power required turn thrust 130 correct value Pl/PN use Eq 2 certainly preferrable 100 actual value changes P/d blade thickness ratio 16 x will about 137 9 x 7 will about 125 propellers have blades thinner Clark-Y 116% automatically reduces camber hence Continued page 128 gi chain no stronger its weakest link ting Part neBeam ScrewDrillpower plant model No eWidth SizeSizePriceplane no better engine mount poorly 909605 049-051650#2 x 3/81/16$169installed vibration 909610 0900#2 x 341/16179generating motor mount 909615 5965#4 x 1/23/32189can cause immeasurable 909620 5120#4 x 1/23/32199trouble airborne 909640 35-40-45130#4 x 1/23/32249system aircraft 909660 0156#6 x 3/47/64299Airtrortics engine mounts 90966161 pump170#6 x 3/47/64299makes difference details complete product line send $100 24-page catalog AirtrOnico products see 1~\ FULL ONE YEAR LIMITED WARRANTY ON ALL EL SYSTEMS local hobby shop E ~AEID~ 12190 WOODRUFF AVENUE Well Prepared answer5K ENEEwUUDOWNEr CALIFORNIA 90241 questions provide youTELEPHONE 213 862-6583 assistance wmw wwuwwumww COMPLETE THIS FORM AND ATTACH MAILING LABEL FROM RECENT ISSUE KNOW WHERE YOU ARE GOING move please let us know advancesix weeks re quired change address Attach current MA mailing label check appropriate box mail Subscription Dept. Model Aviation 815 Fifteenth St NW Washington DC. 20005 Check appropriate boxenclose payment 0 NEW SUBSCRIPTION 0 CHANGE OF ADDRESS Non-AMA subscrIptIon rates $1800 12 months US possessIons elsewhere IncludIng Canada MexIco $2400 US Schools $900 US LIbrarIes $1350 NAME ADDRESS CITY/STATE ___________________________________________ ZIP ______________ MODEL AVIATION 815 FIFTEENTH ST. NW. WASHINGTON DC 20005 AVIATION BOOKS AT DISCOUNTS New Group Discount Plan Zenith Aviation Books Discounts 40% off list prices Nearly 1000 titles around World TWO simple requirements 1 A single check covering order 2 One ship-to address Free catalog discount info & details ZENITH AVIATION BOOKS North Branch MN 55056161 2 583-2573 JUST PUBLISHED Available Group Discount I14ERE ARE NO SECRETS Higley Model finishtng techniques horn m tins 314 photos 16 chap tern ton-Or Comtiots Paint Problems Color Paints Sealets Fillets Ponrets Erushes & 6rushjog Fillets & Cunopren Faint Contents & trying etc 03 ygs softbound 21553C$995 July 198237 Hobbi Shack SUPERMARKET OF HOBBY GOODS SUPER DISCOUNTS PRICES GOOD THRU MAY 82 COXTD049or051 $1747 049 NO 553602 051 NO 553610 HOUSE BALSA 2x2 NO 576377 LIST $2495 1567 DEVCON 5-MINUTE EPOXY NO 566281 LIST $999$576 0-MIDWEST SWEETN LOW NO 569053 LIST $5695. 99 FUTABA SAVINGS FP-4L 3 S26 servos -NO711862eaa LIST $19995 FP-7 FG K jfi with 4 S-26 servos NO 712356 $2499 LIST $39995 9 HUNDREDS MORE SUPER VALUES AND INTERESTING MODEL ARTICLES FREE y Shack customers ceive 32 age SPORT FLYER regularly would like copy simply write us ask FUJI 099 R/C NO 120618 LIST $31 95$1799 PMP THERMAL 73 NO 541492 LIST $2995 788 S HOBBY SHACK HEAT GUN NO 110445 LIST $3295 1499 I0 name address city I statezip U mail order catalogs 18480 BANDILIER CIRCLE 1FOUNTAINVALLEYCA9287081 frequency receiver Jack Albrecht AMA Frequency Committee has taken image problems account making draft Phase-In Plan frequency usage plan followed wont able buy systems suffer image problems leaves 7208/7296 problem familiar will go away five years Till know about careful Some folks already have scanners non-RC bands question bound asked Can use scanner RC answer according John Lange Yes proper converter Once again contact John address call sign given early column precise information need Finally direct attention back cheapest solution could come u ctronic Bird-Dog published Radio Technique January 1982 will monitor channel receiver will monitor very well draws about 300mA order heard above noise engines field wouldnt want leave plugged flight pack very long will completely discharge usual 500 mAh pack less two hours intend con tinuousmonitoring Bird-Dog puta 100ohm resistor series loudspeaker should cut current drain down about 35 mA Keep letters flowing George M Miers 70 Froehlich Farm Rd HieksiiIle NY 11801________ SAFE FLYING IS NO ACCIDENT Neighvion/ Randolph Continued page 35 will find can taxi out spot stop apply power takeoff just would larger plane Dont hurry rotate first flight Apply slight back stick let Neighvion fly off Climb straight out level off trim out original required slight up left trim initial flight Landings quite easy Come back power fly pattern ease off power just before touch-down Smooth time Neighvion smooth solid flier Props Brown lee Con ftnued page 37 l/N As shall see later performance will affected critically pitch long diameter correct let engine develop its maximum power computation purposes value 125 suggested Results obtained using Eq 2 will no better mph value used leads purpose number three starting point equilibrium condition available thrust equals total airframe drag engineering terms Power Out tx velocIty4 Efficiency E r In550 x hp 550 x hp x E thereforeTv4a DCDxOOll9xv2xS5 CD airframe drag coefficient based wing area V velocity feet-per-second S wing area square feet 1 28 Model Aviation GOITIOLINI TEND PROFILE0 COMBA RA T WIDE & NARROW WEDGE 15 -- 6 os Capacities UNIFLOW & TINDD Custom 31il lush Ingredients deraited brochure50C stamps/check CAROLINA TAFFINDER 8345 Delhi Road Charleston Hgts SC 29405 h THE NELSON 15. UN4 VES TION4IL Y THE lEST QUARTER MIDGET AMA C PAl PLUS THE TEXAS 3O complete information Write Kus torn Kraftsmanship Brochure PO Box 2699 Laguna Hills CA 92653 Call f7 14 830-5 162 Dealer inquiries invited IN STOCK FOR IMMEDIATE SHIPMENT NewSUPER QUADRA$9995 wth BRISIGHELLA FLYWHEEL$11995 QUADRA REPAIR51000 plot pent KIORITZ engine 244 c in519995 PUW RADIAL ENGINES FleerS2295 Jorr M ester ERCOUPEPLANS S2395 KIT S22995 Jier M TOMAHAWKPLANS $2395 KIT S245 95 BALSA BASSWOOD oil sicen35% OFF Concept FLEETKIT 517995 F 0 CoW $1995 QUADRA foel tonkO16 0 5695 32 oe S795 VICKERSor LEWIS MACHINE GUN KITS51499 10 RED WHEELS USA Pop$2595 PLANS SUPER STEARMAN reyS250O STARDUSTER TOO ghelleS29 95 scale J-3 CUB Nelde$2995 VDLKSPLANE ken ChorIreS2395 FLY BABY $1696 56-5 ch524RR COCKPIT KITS Tocehewk F4U-1 SprtfrreS21 95 Ercoope $1795 Steerroen 52G 95 Creebrie $2495 I-3 Cob 51950 ME-lOS $21 50 Fleet $1995 FIBERGLASS ARROW SHAFTS 5/16 032 1g6/51000 24-Hour Service. Add $250 postage Send Bank Check Money Order JIM MESSERS QUALITY MODEL PRODUCTS 106 Valley View Dr Allegany NY 14706 hpxE Vmph527CD X Eq 6 must know hp propeller absorbingthe effective poweroutput engine approximate efficiency propeller can attain indicated V latter will vary substantially P/D 16 x 4 being capable about 67% maximum 9 x 7 being able reach about 85% maximum CD will vary greatly depending type aircraft involved can low 0025 up probably high 007 5 heavy slow flying biplane flat cowl lots wing struts wires wire-spoked wheels etc S should easy determine point illustrate much detail information needed calculate flight speed accurately Obviously get close multiplying pitch x rpm x efficiency will accident painless type Eq 6 can however used accurately quantify effect changing parameters involved leaving others fixed will close example involving E Lets suppose observed 11 x 694 propeller flight P real good power plant tuming 15000 rpm time J would 08 x 063 0504 actual V would about 115 fps or784 mph Fig 1 can determine F would about 077 Recognizing propeller operating higher-than-optimum angle attack wish change propellers P pitch reduced d must increased preserve hp net effect J will also decrease about 045 Fig will no longer valid since pitch angle will reduced FCC NPRM Continued aqe 40 making proceeding contact Donald Draper Campbell FCC Office Science Tech nology Spectrum Planning Branch Washing ton DC 20554 telephone 202 653-81 77 Federal Communications Commission William J Tricario Secretary Note 1 26 October 17 November 12 De cember 1979 Note 2 end Academy applied experimental license Part 5 19 August 1980 file number 8272-ER-PL-8o operate four 900 MHz frequencies An experimen tal license KK2XFz issued 28 Janu ary 1981 Note 3 26995 27045 27095 27145 27195 27255 MHz latter frequen cy shared other services Note 4 7208 7216 7224 7232 7240 7296 7564 MHz Continued page 132 SERVO GARD SERVO GARD mon bone fhght battery peck voltage well radio signal received transmitter cod reneiver malfunction detected part system SERVO GARO reduces throttle automatically ample time before battery failure safely land model SPECIFICATIONS Size unit installed KPS-14 servo case easy installation Just plug throttle servo output Weight Approx 1 oz Sensitivity Accurate within 02 Volts Servo Pulse Unit shipped positive pulse systems negative pulse available upon request SERVO GARD comes complete pro-wired pigtails servo connectors choice installed specify connector type orderl SEE YOUR DEALER OR ORDER DIRECT DEALER INOUIRIES IN VI TED Price $3795 Postpaid ISpecify connector typo positive negative pulse orderingl ENDORSED BY THE SPIRIT OF AMERICA SHOW TEAM LIMA OHIO R F Enterprises 106 N Main St Arlington OH 45814 419 365-5360 July 1982 129 Equating Eq 4a Eq. 5 solving y new efficiency curve will somewhat givesleft curve Fig 1 E J will beGet install don t take off about080 andthenewVwillbewithout Ken Willard RCM 6x 7841013 x 784 slight further increase V would result reduced slip stream velocity Such small change would justified desire squeeze last drop performance Out power plant engine plus propeller close hoped points have made clearly Take propellers complicated exciting further hoped article will enable respond definite yes answer asked question title
Edition: Model Aviation - 1982/07
Page Numbers: 36, 37, 128, 129
DoWe Really Understand Ou EHHS math involved determining propeller pitch speed per formance incom prehensible us article spells out stepby-step shows can apply understanding props commonly useEJohn Brownlee John Brownlee 52 has built model aircraft since 1940 AC since late 19505 An engineer says interested aero dynamic theory merely out curiosity MPHOBxPitchxRPMx000947 1 THE TITLE article stems fact Eq 1 widely used calculate either required propeller pitch speed model will fly based nominal propeller pitch inflight rpm As pitch equation identifies correct nominal pitch optimum efficiency propellers symmetrical airfoil airfoil used typical model aircraft propeller possesses considerable camber however Eq 1 does contain sufficient information deal fact As result tends overul U z Ml U U IL Ml 08 06 04 02 0 TfffJ PD -_ IA -----1---K---- --y / / / / 0 02 04 V nD 06 Fig 1 Propeller efficiency vs i Clark Y 15 deg pitch angle state required pitch 25-35% used calculate mph Eq 1 justified assumption moving forward speed equal calculated advance nominal pitch line constitutes condition 100% effici ency Actual efficiency assumed about 80% construed serve speed limiter relative nominal pitch line advance hence 08 term Eq 1 Neither assump tions correct however quite possible observe model flying 14 times speed predicted purposes article 1 Develop equation calculating pitch optimum efficiency can accommodate cambered airfoils 2 Analyze efficiency curve propeller Clark-Y airfoil demonstrate optimum efficiency can result propeller moving forward faster calculated pitch line advance speed 3 Develop correct equation calculating level flight speed order point out parameters must known order achieve acceptable accuracy Normally propeller performance power absorption function J-F actor Advance Ratio quantitatively V/nD V forward velocity feet per sec 1467 x mph n propeller revolutions per second rpm/60 D diameter feetd/l 2 observed plane flying 60 mph 08 airfoil Two blades 10-in propeller tuming 12000 rpm J would found follows 1467 x60 v2000lOos28 60 12 consider effective pitch P propeller above example find lOS6xmph 1056x60 528 rpm12000 Since above calculations differ fact diameter considered P follows P D P d P having dimensions assigned diameter feet inches should also noted P has no relationship whatsoever actual propeller pitch will vary restraint imposed forward progress Now assume restraintdrag removed example propeller just enough power applied maintain 12000 rpm propeller would gain speed until reached point no thrust lift could generated efficiency would zero Lets call point Jll wouldbeJ1xd brief glance Fig 1 will show propeller efficiency value reaches maximum some point between J0 J1 Lets call M M would M x d 36 Model Aviation addition changeable effective pitch fixed-pitch propeller must also possess un changeable nominalpitch pitch designation contains information required construct propeller must therefore answer equation calculate pitch efficiency Lets call pitch N- no direct J counterpart N can shown J propeller will moving forward speed equal calculated nominal pitch line advance speed Now lets assume access large number curves like Fig 1 covering propellers various pitch angles number blades airfoils etc careful scrutiny concluded J 1 propeller efficiencies near maximum willing ignore slight deviations could say M0•8 P1 Thisiswheretheterm08 inEq originates coincidence efficiency 80% 08 P1 propellers very low pitch angles 92-93% efficiency will realized may also write P1 M Substitut ing mph target specified rpm gives Ia 1056 xmph P1125x rpm Eq 1 rearranged does result useful answer since N considered Mathematically can divide both sides 1/N changing equation gives 125 lOS6xmph lN rpm 2 Eq 2 cannot solved rationally since ij appears both sides knowing 1/N function amount camber airfoil used solving Eq 1 calling result N assume 1/N 100 practical purposes true symmetrical airfoils Eq 2 can seen 1/N 125 optimum efficiency within limits imposed our08 J1 compro mise will realized propeller moving forward pitch line advance speed 1/N greater 125 optimum effici ency will realized propeller Out running its pitch Moving second purpose lets look Fig 1 detail see what camber Clark Y airfoil does 1/N ratio curve purloined old aerodynamic treatise applicable models because pitch angle 075 R radius range commonly used J1 about 082 diameter 11 inches P1 would about 92 inches N found follows tan pitch angle x 314 x d x r/R 3 x 314 x 11 x 75 1/N 902/694 130 know propeller will running 130/125 104 times fast its nominal pitch line advance 1 0656 P/d 11 063 and0656/063 naturally 104 also can further see 070/063 times nominal pitch line advance speed propeller still converting 80% power required turn thrust 130 correct value Pl/PN use Eq 2 certainly preferrable 100 actual value changes P/d blade thickness ratio 16 x will about 137 9 x 7 will about 125 propellers have blades thinner Clark-Y 116% automatically reduces camber hence Continued page 128 gi chain no stronger its weakest link ting Part neBeam ScrewDrillpower plant model No eWidth SizeSizePriceplane no better engine mount poorly 909605 049-051650#2 x 3/81/16$169installed vibration 909610 0900#2 x 341/16179generating motor mount 909615 5965#4 x 1/23/32189can cause immeasurable 909620 5120#4 x 1/23/32199trouble airborne 909640 35-40-45130#4 x 1/23/32249system aircraft 909660 0156#6 x 3/47/64299Airtrortics engine mounts 90966161 pump170#6 x 3/47/64299makes difference details complete product line send $100 24-page catalog AirtrOnico products see 1~\ FULL ONE YEAR LIMITED WARRANTY ON ALL EL SYSTEMS local hobby shop E ~AEID~ 12190 WOODRUFF AVENUE Well Prepared answer5K ENEEwUUDOWNEr CALIFORNIA 90241 questions provide youTELEPHONE 213 862-6583 assistance wmw wwuwwumww COMPLETE THIS FORM AND ATTACH MAILING LABEL FROM RECENT ISSUE KNOW WHERE YOU ARE GOING move please let us know advancesix weeks re quired change address Attach current MA mailing label check appropriate box mail Subscription Dept. Model Aviation 815 Fifteenth St NW Washington DC. 20005 Check appropriate boxenclose payment 0 NEW SUBSCRIPTION 0 CHANGE OF ADDRESS Non-AMA subscrIptIon rates $1800 12 months US possessIons elsewhere IncludIng Canada MexIco $2400 US Schools $900 US LIbrarIes $1350 NAME ADDRESS CITY/STATE ___________________________________________ ZIP ______________ MODEL AVIATION 815 FIFTEENTH ST. NW. WASHINGTON DC 20005 AVIATION BOOKS AT DISCOUNTS New Group Discount Plan Zenith Aviation Books Discounts 40% off list prices Nearly 1000 titles around World TWO simple requirements 1 A single check covering order 2 One ship-to address Free catalog discount info & details ZENITH AVIATION BOOKS North Branch MN 55056161 2 583-2573 JUST PUBLISHED Available Group Discount I14ERE ARE NO SECRETS Higley Model finishtng techniques horn m tins 314 photos 16 chap tern ton-Or Comtiots Paint Problems Color Paints Sealets Fillets Ponrets Erushes & 6rushjog Fillets & Cunopren Faint Contents & trying etc 03 ygs softbound 21553C$995 July 198237 Hobbi Shack SUPERMARKET OF HOBBY GOODS SUPER DISCOUNTS PRICES GOOD THRU MAY 82 COXTD049or051 $1747 049 NO 553602 051 NO 553610 HOUSE BALSA 2x2 NO 576377 LIST $2495 1567 DEVCON 5-MINUTE EPOXY NO 566281 LIST $999$576 0-MIDWEST SWEETN LOW NO 569053 LIST $5695. 99 FUTABA SAVINGS FP-4L 3 S26 servos -NO711862eaa LIST $19995 FP-7 FG K jfi with 4 S-26 servos NO 712356 $2499 LIST $39995 9 HUNDREDS MORE SUPER VALUES AND INTERESTING MODEL ARTICLES FREE y Shack customers ceive 32 age SPORT FLYER regularly would like copy simply write us ask FUJI 099 R/C NO 120618 LIST $31 95$1799 PMP THERMAL 73 NO 541492 LIST $2995 788 S HOBBY SHACK HEAT GUN NO 110445 LIST $3295 1499 I0 name address city I statezip U mail order catalogs 18480 BANDILIER CIRCLE 1FOUNTAINVALLEYCA9287081 frequency receiver Jack Albrecht AMA Frequency Committee has taken image problems account making draft Phase-In Plan frequency usage plan followed wont able buy systems suffer image problems leaves 7208/7296 problem familiar will go away five years Till know about careful Some folks already have scanners non-RC bands question bound asked Can use scanner RC answer according John Lange Yes proper converter Once again contact John address call sign given early column precise information need Finally direct attention back cheapest solution could come u ctronic Bird-Dog published Radio Technique January 1982 will monitor channel receiver will monitor very well draws about 300mA order heard above noise engines field wouldnt want leave plugged flight pack very long will completely discharge usual 500 mAh pack less two hours intend con tinuousmonitoring Bird-Dog puta 100ohm resistor series loudspeaker should cut current drain down about 35 mA Keep letters flowing George M Miers 70 Froehlich Farm Rd HieksiiIle NY 11801________ SAFE FLYING IS NO ACCIDENT Neighvion/ Randolph Continued page 35 will find can taxi out spot stop apply power takeoff just would larger plane Dont hurry rotate first flight Apply slight back stick let Neighvion fly off Climb straight out level off trim out original required slight up left trim initial flight Landings quite easy Come back power fly pattern ease off power just before touch-down Smooth time Neighvion smooth solid flier Props Brown lee Con ftnued page 37 l/N As shall see later performance will affected critically pitch long diameter correct let engine develop its maximum power computation purposes value 125 suggested Results obtained using Eq 2 will no better mph value used leads purpose number three starting point equilibrium condition available thrust equals total airframe drag engineering terms Power Out tx velocIty4 Efficiency E r In550 x hp 550 x hp x E thereforeTv4a DCDxOOll9xv2xS5 CD airframe drag coefficient based wing area V velocity feet-per-second S wing area square feet 1 28 Model Aviation GOITIOLINI TEND PROFILE0 COMBA RA T WIDE & NARROW WEDGE 15 -- 6 os Capacities UNIFLOW & TINDD Custom 31il lush Ingredients deraited brochure50C stamps/check CAROLINA TAFFINDER 8345 Delhi Road Charleston Hgts SC 29405 h THE NELSON 15. UN4 VES TION4IL Y THE lEST QUARTER MIDGET AMA C PAl PLUS THE TEXAS 3O complete information Write Kus torn Kraftsmanship Brochure PO Box 2699 Laguna Hills CA 92653 Call f7 14 830-5 162 Dealer inquiries invited IN STOCK FOR IMMEDIATE SHIPMENT NewSUPER QUADRA$9995 wth BRISIGHELLA FLYWHEEL$11995 QUADRA REPAIR51000 plot pent KIORITZ engine 244 c in519995 PUW RADIAL ENGINES FleerS2295 Jorr M ester ERCOUPEPLANS S2395 KIT S22995 Jier M TOMAHAWKPLANS $2395 KIT S245 95 BALSA BASSWOOD oil sicen35% OFF Concept FLEETKIT 517995 F 0 CoW $1995 QUADRA foel tonkO16 0 5695 32 oe S795 VICKERSor LEWIS MACHINE GUN KITS51499 10 RED WHEELS USA Pop$2595 PLANS SUPER STEARMAN reyS250O STARDUSTER TOO ghelleS29 95 scale J-3 CUB Nelde$2995 VDLKSPLANE ken ChorIreS2395 FLY BABY $1696 56-5 ch524RR COCKPIT KITS Tocehewk F4U-1 SprtfrreS21 95 Ercoope $1795 Steerroen 52G 95 Creebrie $2495 I-3 Cob 51950 ME-lOS $21 50 Fleet $1995 FIBERGLASS ARROW SHAFTS 5/16 032 1g6/51000 24-Hour Service. Add $250 postage Send Bank Check Money Order JIM MESSERS QUALITY MODEL PRODUCTS 106 Valley View Dr Allegany NY 14706 hpxE Vmph527CD X Eq 6 must know hp propeller absorbingthe effective poweroutput engine approximate efficiency propeller can attain indicated V latter will vary substantially P/D 16 x 4 being capable about 67% maximum 9 x 7 being able reach about 85% maximum CD will vary greatly depending type aircraft involved can low 0025 up probably high 007 5 heavy slow flying biplane flat cowl lots wing struts wires wire-spoked wheels etc S should easy determine point illustrate much detail information needed calculate flight speed accurately Obviously get close multiplying pitch x rpm x efficiency will accident painless type Eq 6 can however used accurately quantify effect changing parameters involved leaving others fixed will close example involving E Lets suppose observed 11 x 694 propeller flight P real good power plant tuming 15000 rpm time J would 08 x 063 0504 actual V would about 115 fps or784 mph Fig 1 can determine F would about 077 Recognizing propeller operating higher-than-optimum angle attack wish change propellers P pitch reduced d must increased preserve hp net effect J will also decrease about 045 Fig will no longer valid since pitch angle will reduced FCC NPRM Continued aqe 40 making proceeding contact Donald Draper Campbell FCC Office Science Tech nology Spectrum Planning Branch Washing ton DC 20554 telephone 202 653-81 77 Federal Communications Commission William J Tricario Secretary Note 1 26 October 17 November 12 De cember 1979 Note 2 end Academy applied experimental license Part 5 19 August 1980 file number 8272-ER-PL-8o operate four 900 MHz frequencies An experimen tal license KK2XFz issued 28 Janu ary 1981 Note 3 26995 27045 27095 27145 27195 27255 MHz latter frequen cy shared other services Note 4 7208 7216 7224 7232 7240 7296 7564 MHz Continued page 132 SERVO GARD SERVO GARD mon bone fhght battery peck voltage well radio signal received transmitter cod reneiver malfunction detected part system SERVO GARO reduces throttle automatically ample time before battery failure safely land model SPECIFICATIONS Size unit installed KPS-14 servo case easy installation Just plug throttle servo output Weight Approx 1 oz Sensitivity Accurate within 02 Volts Servo Pulse Unit shipped positive pulse systems negative pulse available upon request SERVO GARD comes complete pro-wired pigtails servo connectors choice installed specify connector type orderl SEE YOUR DEALER OR ORDER DIRECT DEALER INOUIRIES IN VI TED Price $3795 Postpaid ISpecify connector typo positive negative pulse orderingl ENDORSED BY THE SPIRIT OF AMERICA SHOW TEAM LIMA OHIO R F Enterprises 106 N Main St Arlington OH 45814 419 365-5360 July 1982 129 Equating Eq 4a Eq. 5 solving y new efficiency curve will somewhat givesleft curve Fig 1 E J will beGet install don t take off about080 andthenewVwillbewithout Ken Willard RCM 6x 7841013 x 784 slight further increase V would result reduced slip stream velocity Such small change would justified desire squeeze last drop performance Out power plant engine plus propeller close hoped points have made clearly Take propellers complicated exciting further hoped article will enable respond definite yes answer asked question title
Edition: Model Aviation - 1982/07
Page Numbers: 36, 37, 128, 129
DoWe Really Understand Ou EHHS math involved determining propeller pitch speed per formance incom prehensible us article spells out stepby-step shows can apply understanding props commonly useEJohn Brownlee John Brownlee 52 has built model aircraft since 1940 AC since late 19505 An engineer says interested aero dynamic theory merely out curiosity MPHOBxPitchxRPMx000947 1 THE TITLE article stems fact Eq 1 widely used calculate either required propeller pitch speed model will fly based nominal propeller pitch inflight rpm As pitch equation identifies correct nominal pitch optimum efficiency propellers symmetrical airfoil airfoil used typical model aircraft propeller possesses considerable camber however Eq 1 does contain sufficient information deal fact As result tends overul U z Ml U U IL Ml 08 06 04 02 0 TfffJ PD -_ IA -----1---K---- --y / / / / 0 02 04 V nD 06 Fig 1 Propeller efficiency vs i Clark Y 15 deg pitch angle state required pitch 25-35% used calculate mph Eq 1 justified assumption moving forward speed equal calculated advance nominal pitch line constitutes condition 100% effici ency Actual efficiency assumed about 80% construed serve speed limiter relative nominal pitch line advance hence 08 term Eq 1 Neither assump tions correct however quite possible observe model flying 14 times speed predicted purposes article 1 Develop equation calculating pitch optimum efficiency can accommodate cambered airfoils 2 Analyze efficiency curve propeller Clark-Y airfoil demonstrate optimum efficiency can result propeller moving forward faster calculated pitch line advance speed 3 Develop correct equation calculating level flight speed order point out parameters must known order achieve acceptable accuracy Normally propeller performance power absorption function J-F actor Advance Ratio quantitatively V/nD V forward velocity feet per sec 1467 x mph n propeller revolutions per second rpm/60 D diameter feetd/l 2 observed plane flying 60 mph 08 airfoil Two blades 10-in propeller tuming 12000 rpm J would found follows 1467 x60 v2000lOos28 60 12 consider effective pitch P propeller above example find lOS6xmph 1056x60 528 rpm12000 Since above calculations differ fact diameter considered P follows P D P d P having dimensions assigned diameter feet inches should also noted P has no relationship whatsoever actual propeller pitch will vary restraint imposed forward progress Now assume restraintdrag removed example propeller just enough power applied maintain 12000 rpm propeller would gain speed until reached point no thrust lift could generated efficiency would zero Lets call point Jll wouldbeJ1xd brief glance Fig 1 will show propeller efficiency value reaches maximum some point between J0 J1 Lets call M M would M x d 36 Model Aviation addition changeable effective pitch fixed-pitch propeller must also possess un changeable nominalpitch pitch designation contains information required construct propeller must therefore answer equation calculate pitch efficiency Lets call pitch N- no direct J counterpart N can shown J propeller will moving forward speed equal calculated nominal pitch line advance speed Now lets assume access large number curves like Fig 1 covering propellers various pitch angles number blades airfoils etc careful scrutiny concluded J 1 propeller efficiencies near maximum willing ignore slight deviations could say M0•8 P1 Thisiswheretheterm08 inEq originates coincidence efficiency 80% 08 P1 propellers very low pitch angles 92-93% efficiency will realized may also write P1 M Substitut ing mph target specified rpm gives Ia 1056 xmph P1125x rpm Eq 1 rearranged does result useful answer since N considered Mathematically can divide both sides 1/N changing equation gives 125 lOS6xmph lN rpm 2 Eq 2 cannot solved rationally since ij appears both sides knowing 1/N function amount camber airfoil used solving Eq 1 calling result N assume 1/N 100 practical purposes true symmetrical airfoils Eq 2 can seen 1/N 125 optimum efficiency within limits imposed our08 J1 compro mise will realized propeller moving forward pitch line advance speed 1/N greater 125 optimum effici ency will realized propeller Out running its pitch Moving second purpose lets look Fig 1 detail see what camber Clark Y airfoil does 1/N ratio curve purloined old aerodynamic treatise applicable models because pitch angle 075 R radius range commonly used J1 about 082 diameter 11 inches P1 would about 92 inches N found follows tan pitch angle x 314 x d x r/R 3 x 314 x 11 x 75 1/N 902/694 130 know propeller will running 130/125 104 times fast its nominal pitch line advance 1 0656 P/d 11 063 and0656/063 naturally 104 also can further see 070/063 times nominal pitch line advance speed propeller still converting 80% power required turn thrust 130 correct value Pl/PN use Eq 2 certainly preferrable 100 actual value changes P/d blade thickness ratio 16 x will about 137 9 x 7 will about 125 propellers have blades thinner Clark-Y 116% automatically reduces camber hence Continued page 128 gi chain no stronger its weakest link ting Part neBeam ScrewDrillpower plant model No eWidth SizeSizePriceplane no better engine mount poorly 909605 049-051650#2 x 3/81/16$169installed vibration 909610 0900#2 x 341/16179generating motor mount 909615 5965#4 x 1/23/32189can cause immeasurable 909620 5120#4 x 1/23/32199trouble airborne 909640 35-40-45130#4 x 1/23/32249system aircraft 909660 0156#6 x 3/47/64299Airtrortics engine mounts 90966161 pump170#6 x 3/47/64299makes difference details complete product line send $100 24-page catalog AirtrOnico products see 1~\ FULL ONE YEAR LIMITED WARRANTY ON ALL EL SYSTEMS local hobby shop E ~AEID~ 12190 WOODRUFF AVENUE Well Prepared answer5K ENEEwUUDOWNEr CALIFORNIA 90241 questions provide youTELEPHONE 213 862-6583 assistance wmw wwuwwumww COMPLETE THIS FORM AND ATTACH MAILING LABEL FROM RECENT ISSUE KNOW WHERE YOU ARE GOING move please let us know advancesix weeks re quired change address Attach current MA mailing label check appropriate box mail Subscription Dept. Model Aviation 815 Fifteenth St NW Washington DC. 20005 Check appropriate boxenclose payment 0 NEW SUBSCRIPTION 0 CHANGE OF ADDRESS Non-AMA subscrIptIon rates $1800 12 months US possessIons elsewhere IncludIng Canada MexIco $2400 US Schools $900 US LIbrarIes $1350 NAME ADDRESS CITY/STATE ___________________________________________ ZIP ______________ MODEL AVIATION 815 FIFTEENTH ST. NW. WASHINGTON DC 20005 AVIATION BOOKS AT DISCOUNTS New Group Discount Plan Zenith Aviation Books Discounts 40% off list prices Nearly 1000 titles around World TWO simple requirements 1 A single check covering order 2 One ship-to address Free catalog discount info & details ZENITH AVIATION BOOKS North Branch MN 55056161 2 583-2573 JUST PUBLISHED Available Group Discount I14ERE ARE NO SECRETS Higley Model finishtng techniques horn m tins 314 photos 16 chap tern ton-Or Comtiots Paint Problems Color Paints Sealets Fillets Ponrets Erushes & 6rushjog Fillets & Cunopren Faint Contents & trying etc 03 ygs softbound 21553C$995 July 198237 Hobbi Shack SUPERMARKET OF HOBBY GOODS SUPER DISCOUNTS PRICES GOOD THRU MAY 82 COXTD049or051 $1747 049 NO 553602 051 NO 553610 HOUSE BALSA 2x2 NO 576377 LIST $2495 1567 DEVCON 5-MINUTE EPOXY NO 566281 LIST $999$576 0-MIDWEST SWEETN LOW NO 569053 LIST $5695. 99 FUTABA SAVINGS FP-4L 3 S26 servos -NO711862eaa LIST $19995 FP-7 FG K jfi with 4 S-26 servos NO 712356 $2499 LIST $39995 9 HUNDREDS MORE SUPER VALUES AND INTERESTING MODEL ARTICLES FREE y Shack customers ceive 32 age SPORT FLYER regularly would like copy simply write us ask FUJI 099 R/C NO 120618 LIST $31 95$1799 PMP THERMAL 73 NO 541492 LIST $2995 788 S HOBBY SHACK HEAT GUN NO 110445 LIST $3295 1499 I0 name address city I statezip U mail order catalogs 18480 BANDILIER CIRCLE 1FOUNTAINVALLEYCA9287081 frequency receiver Jack Albrecht AMA Frequency Committee has taken image problems account making draft Phase-In Plan frequency usage plan followed wont able buy systems suffer image problems leaves 7208/7296 problem familiar will go away five years Till know about careful Some folks already have scanners non-RC bands question bound asked Can use scanner RC answer according John Lange Yes proper converter Once again contact John address call sign given early column precise information need Finally direct attention back cheapest solution could come u ctronic Bird-Dog published Radio Technique January 1982 will monitor channel receiver will monitor very well draws about 300mA order heard above noise engines field wouldnt want leave plugged flight pack very long will completely discharge usual 500 mAh pack less two hours intend con tinuousmonitoring Bird-Dog puta 100ohm resistor series loudspeaker should cut current drain down about 35 mA Keep letters flowing George M Miers 70 Froehlich Farm Rd HieksiiIle NY 11801________ SAFE FLYING IS NO ACCIDENT Neighvion/ Randolph Continued page 35 will find can taxi out spot stop apply power takeoff just would larger plane Dont hurry rotate first flight Apply slight back stick let Neighvion fly off Climb straight out level off trim out original required slight up left trim initial flight Landings quite easy Come back power fly pattern ease off power just before touch-down Smooth time Neighvion smooth solid flier Props Brown lee Con ftnued page 37 l/N As shall see later performance will affected critically pitch long diameter correct let engine develop its maximum power computation purposes value 125 suggested Results obtained using Eq 2 will no better mph value used leads purpose number three starting point equilibrium condition available thrust equals total airframe drag engineering terms Power Out tx velocIty4 Efficiency E r In550 x hp 550 x hp x E thereforeTv4a DCDxOOll9xv2xS5 CD airframe drag coefficient based wing area V velocity feet-per-second S wing area square feet 1 28 Model Aviation GOITIOLINI TEND PROFILE0 COMBA RA T WIDE & NARROW WEDGE 15 -- 6 os Capacities UNIFLOW & TINDD Custom 31il lush Ingredients deraited brochure50C stamps/check CAROLINA TAFFINDER 8345 Delhi Road Charleston Hgts SC 29405 h THE NELSON 15. UN4 VES TION4IL Y THE lEST QUARTER MIDGET AMA C PAl PLUS THE TEXAS 3O complete information Write Kus torn Kraftsmanship Brochure PO Box 2699 Laguna Hills CA 92653 Call f7 14 830-5 162 Dealer inquiries invited IN STOCK FOR IMMEDIATE SHIPMENT NewSUPER QUADRA$9995 wth BRISIGHELLA FLYWHEEL$11995 QUADRA REPAIR51000 plot pent KIORITZ engine 244 c in519995 PUW RADIAL ENGINES FleerS2295 Jorr M ester ERCOUPEPLANS S2395 KIT S22995 Jier M TOMAHAWKPLANS $2395 KIT S245 95 BALSA BASSWOOD oil sicen35% OFF Concept FLEETKIT 517995 F 0 CoW $1995 QUADRA foel tonkO16 0 5695 32 oe S795 VICKERSor LEWIS MACHINE GUN KITS51499 10 RED WHEELS USA Pop$2595 PLANS SUPER STEARMAN reyS250O STARDUSTER TOO ghelleS29 95 scale J-3 CUB Nelde$2995 VDLKSPLANE ken ChorIreS2395 FLY BABY $1696 56-5 ch524RR COCKPIT KITS Tocehewk F4U-1 SprtfrreS21 95 Ercoope $1795 Steerroen 52G 95 Creebrie $2495 I-3 Cob 51950 ME-lOS $21 50 Fleet $1995 FIBERGLASS ARROW SHAFTS 5/16 032 1g6/51000 24-Hour Service. Add $250 postage Send Bank Check Money Order JIM MESSERS QUALITY MODEL PRODUCTS 106 Valley View Dr Allegany NY 14706 hpxE Vmph527CD X Eq 6 must know hp propeller absorbingthe effective poweroutput engine approximate efficiency propeller can attain indicated V latter will vary substantially P/D 16 x 4 being capable about 67% maximum 9 x 7 being able reach about 85% maximum CD will vary greatly depending type aircraft involved can low 0025 up probably high 007 5 heavy slow flying biplane flat cowl lots wing struts wires wire-spoked wheels etc S should easy determine point illustrate much detail information needed calculate flight speed accurately Obviously get close multiplying pitch x rpm x efficiency will accident painless type Eq 6 can however used accurately quantify effect changing parameters involved leaving others fixed will close example involving E Lets suppose observed 11 x 694 propeller flight P real good power plant tuming 15000 rpm time J would 08 x 063 0504 actual V would about 115 fps or784 mph Fig 1 can determine F would about 077 Recognizing propeller operating higher-than-optimum angle attack wish change propellers P pitch reduced d must increased preserve hp net effect J will also decrease about 045 Fig will no longer valid since pitch angle will reduced FCC NPRM Continued aqe 40 making proceeding contact Donald Draper Campbell FCC Office Science Tech nology Spectrum Planning Branch Washing ton DC 20554 telephone 202 653-81 77 Federal Communications Commission William J Tricario Secretary Note 1 26 October 17 November 12 De cember 1979 Note 2 end Academy applied experimental license Part 5 19 August 1980 file number 8272-ER-PL-8o operate four 900 MHz frequencies An experimen tal license KK2XFz issued 28 Janu ary 1981 Note 3 26995 27045 27095 27145 27195 27255 MHz latter frequen cy shared other services Note 4 7208 7216 7224 7232 7240 7296 7564 MHz Continued page 132 SERVO GARD SERVO GARD mon bone fhght battery peck voltage well radio signal received transmitter cod reneiver malfunction detected part system SERVO GARO reduces throttle automatically ample time before battery failure safely land model SPECIFICATIONS Size unit installed KPS-14 servo case easy installation Just plug throttle servo output Weight Approx 1 oz Sensitivity Accurate within 02 Volts Servo Pulse Unit shipped positive pulse systems negative pulse available upon request SERVO GARD comes complete pro-wired pigtails servo connectors choice installed specify connector type orderl SEE YOUR DEALER OR ORDER DIRECT DEALER INOUIRIES IN VI TED Price $3795 Postpaid ISpecify connector typo positive negative pulse orderingl ENDORSED BY THE SPIRIT OF AMERICA SHOW TEAM LIMA OHIO R F Enterprises 106 N Main St Arlington OH 45814 419 365-5360 July 1982 129 Equating Eq 4a Eq. 5 solving y new efficiency curve will somewhat givesleft curve Fig 1 E J will beGet install don t take off about080 andthenewVwillbewithout Ken Willard RCM 6x 7841013 x 784 slight further increase V would result reduced slip stream velocity Such small change would justified desire squeeze last drop performance Out power plant engine plus propeller close hoped points have made clearly Take propellers complicated exciting further hoped article will enable respond definite yes answer asked question title