Radio Control Sport & Aerobatics Ron Van Putte LETTERS got lettersstacks stacks letters Modelers get windy subject wind effects course letters took exception contention airplane unaware steady wind Very few people will write agree opponents dont hesitate notable exception Gene Mathis Daphne AL wrote appreciate effort put wind myth/optical illusion rest true aircraft can feel wind yours truly countless other professional pilots navigators would have spared lot heartburn trying answer essential question whence cometh wind strong does bloweth instance out middle Pacific navigator could have said standard-rate 3600 turn holding airspeed constant will keep eye directional gyro altimeter start climbing diving well know direction wind Based experience can also tell magnitude wind Alas wont work early days high-altitude fly ing jet streams ig norant played havoc navigation because blundered totally unaware Egad navigator redo sumswe cant bucking 150-knot headwind Anyone observing contrail knows stays lined up longitudinal axis aircraft flying athwart jet stream have little fun disbelievers Use long crepe streamer smoke fly straight level course crosswind over troops get variance safety rule demonstration will see although aircraft crabbing streamer smoke will remain perfectly trail position line airplane R VP old pro Bill Winter wrote some thing along ago about oversized fin causing weathervaning know demolishing cherished myth impossible Thanks Gene Impossible tend keep trying Fortunately theres help John Preston great example effects wind August col umn Safety Comes First Check out havent read As mentioned earlier people wrote agree airplane doesnt know steady wind blowing Several argued no such thing steady wind WIND DIRECTION NOWIND TURN -7 F 7 TURN DONE IN WIND C DOWNWIND FIGURE 1 #1 WIND DIRECTION Ron dares wrath readers discussion about effects wind flight models time its about upwind downwind turns RC pilot does under stand winds effects model hes really looking troubleand maybe crashl 44 Model Aviation Fine flight shot Mike Gretz Glen Howards original Ziin Z-50L Sig IMAC Championships model light 6 lbpowered K&B 61 Glen Peoria IL G F NOWIND TURN D c di UPWIND AFIGURE 2 others claimed what observed resulted wind shear layers near ground few puzzled about what observed heavy wind situa tions Most rest genuinely believe airplane feels wind Typical such letters Allan Kass Big Sky MT wrote Im questioning plane may ap pear dive goes downwind ap pear climb goes upwind after flying real thing thousands hours know crosswind take off turn downwind has mushy control feel opposed turn wind control response brisk Ive model planes sink mush back ground first turn after cross wind takeoff downwind flying 22-pound Quarter-Scaler 35-knot wind devil time turning up wind got broadside didnt Continued page 134 EIGHTH ANNUAL [gill [v32]Ufi 1 *1 JANUARY 12 & 13 1985 SEE WITH MAJOR AIRCRAFT BOATS CARS MODEL MODEL MODEL THE LATEST PRODUCTS AND VISIT MANUFACTURERS AND DISTRIBUTORS OF 0 S MODEL ENGINES RADIO CONTROL SYSTEMS MODELING ACCESSORIES PEST 1* WEST *VA IC DISPLAY COMPETITION IN MANY CATEGORIES November 1984 45 Keep cool flight line Solar-powered fan-hat cools forehead evaporating sweat gimmickbut coats $8995 Energy Sciences inc 832 Rockviiie Pike Rockyilie MD 20852 - BN ATNew Turnarouna airpiane Dy U Eagle Inc PO Box 1902 Greenville TX 7540118 named Elliptic Span 70 wing area 865 sq Construction balsa ply Attrac tive model provides alternative CAP-21s Lasers event 3 IUVEWSftA LXHIH UWS GunuII-ILL Y INVI LUI INTERNATIONAL MODELER SHOW OFFICE PO Box 10127 Costa Mesa CA 92627 Ph 714 548-4700 645-88301 TIDEWATER ENGR & MACH Co I4~ PO B0X1135BASTROP LA 71220 MICROMOTORSPHONE 318- 281-2460US DISTRIBUTOR MARINE & CAR ENGINE SPECIALS P-21 Car SE$6500P21 Marine SE$6500P65 Marine $9000 P-21 Car RE$6500P-21 Marine RE$6500P80 Marine $11000 P-21 Buggy SE$6500 P-21 Delta$7500P-45 Marine$7800P90 Marine $14000 AERO ENGINESPECIALS P-21 SE$5000P-45 SE$6000P-80 SE$9000 P21 RE$5500P60 SE$8500P-80 RE$9500 P-40 $6500P60 RE$9000P80 Duct Fan $10000 P-40 SE$5800 P-4b Duct Fan$7500P-65 Duct Fan $9500 TWO NEW MARINE ENGINES P45 Mar-Disc Rotor Valve $8500 P90 Mar-Disc Rotor Valve New Carb $14000 number value enclosed paren theses thickness ordinates directly scalable other exact ordinates can scaled make 12% sec tions charts will correctly 6X X12 Otherwise will 6X, z XXX sections smooth sections superi drag very high RN have somehwat lower CL max far superior high Mach numbers delaying force divergence significantly changing lift moment characteristics severely high subsonic speeds have rather large negative pitching mo ments normally used fairly low CL moment can designed out part combining swept wings washout original 1series sections 16-XXX shapes used propellers because better performance high Mach numbers commonly called 16- series airfoils RN about 12 million mini mum profile drag sections will about same four- five-digit sections same thickness Below suffer earlier laminar separa tion higher drag shapes down RN about 70 thousand below drag airfoils becomes mostly pressure drag due laminar separation no reason use sec tions model application other scale fidelity make nice flying wings however relatively sharp leading edges have caused no problems variety scratchbuilt planes conclude hoped tables can future practical use comments have clear interest information condensed primarily Theory Wing Sections Abbott von Doenhoff RC AerobaticslVan Putte Continued page 45 want go remainder turn almost like sailboat irons Whyif doesnt know wind blowing think virtually questions contained Allan Kass letter lot other letters received can answered considering frame ref erence observer fly ing RC usually standing ground attempting make air plane fly maneuvers prescribed man ner regardless wind blowing may have heard about danger ous downwind turn downwind turn 1800 turn started airplane heading downwind Usually turn starts out right little past halfway around airplane stalls out crashes Basically its because pilot crashed wind con tributing factor pilots faulty understanding effects wind causes stall crash Figure 1 shows top view l8O turn both steady wind wind downwind assumed control inputs same both cases effect wind can have move ground track airplane downwind relative no wind track movement ground track function fast wind blowing long has since turn started hash marks respective turns equal time crements Since effect wind constant its effect ground track constant additive other words points B B certain distance apart points C C will twice far apart points D D will three times far apart looks pretty wild doesnt Well pilot trying perform turn looks like no-wind gets upset starts go astray course stand ard correction increase roll angle pull Up elevator track still doesnt look right pilot keeps creasing roll angle pulling Up elevator Surpriselthe airplane just stalled out Its known accelerated stall stall occurs airplane puffing lot Gs isnt like normal stall Since airplane high speed stall happens very abruptly airplane often crashes before pilot can anything way take another look track airplane wind does look like reluctant come around wind until last part turn doesnt no magic involved observers view turn appears indicate strange things happening because observer fixed airplane moving relative wind youd like another thrill take look Figure 2 airplane starts 180 0turn heading upwind comparison same turn shown no-wind situation identical control input Again theres no magic involved fixed observer airplane again appears doing strange things No wonder beginners often get shook make kind turn airplane appears jump back Strange things happen loops too Ill cover later column Thats enough effects wind month heard about costly crash think would valuable lesson us planning change RC equipment new frequencies seems flier took equipment repairman routine maintenance have frequency changed got back assumed equip ment top shape new fre quency bill didnt say specifically what done equipment went contest got shot down because repairman never changed fre quency fault dont know have frequency change future Ill make sure bill dicates what done mystery plane appeared September issue El Gringo 60-size Slicker according Bill Dennis Amarillo TX Bill used trike gear 40-size Slicker place 1972 Canadian Nats Rebel Rally Jacksonville FL way Bill would like modelers interested plans old Stormer IV know has available $12 set Write Sky Fllte Models 20 Windsor Amarillo TX 79106 being written just before 84 134 Model Aviation Model Magic Filler Quick setting Light weight Non shrinking Fillets Gap filling Ding repair See dealer urst Model Magic Products Model Magic Products PO Box 7784St Paul Minn 55119 715 425-1397 $595 Retail 8 fI oz Adhesion Balsa Foam Fiberglass Strength Flexing Spreading Fuel Resistance Sanding Hardness Finishing Shelf Life Tint Acceptance Water Resistance Comparison Chart Model Magic Excellent Product X Very Poor a Good As medium balsa As Hard Balsa Any fish/covering till used up Excellent Soft balsa Soft balsa ail Spoils i 5lmo Very Poor Test methods arid data avalable request care enough fill very best uisast Model Magc Fler Circus Magic FiNer Nats start Id love cant Nats RC Pattern coverage will handled Steve McCann Pete Callas members National Society Radio Controlled Aerobatics Pete Steve co-District 7 Vice Presidents NSRCA jointly author District 7 submission K-Factor newsletter NSRCA always look forward K-Factor articles know real treat Nats coverage Ron Van Putte 111 Sleepy Oaks Rd Ft Walton Beach FL 32S48 RO ScalelWlschers Continued page 47 reduced real planes power 1/S3 weight factor l/V speed factor Using Y-scale 65 hp Piper Cub example power re quired would 65 p 65 hp Continental engine turned 72-in-diameter prop 2400 rpm 18-in scale-size prop used must turn faster square root scale fac tor 2400 x -VT rpm example A-scale plane given keep math easy results however 108-in-span plane weighing 12 lbsnot exactly schoolyard flier Lets see what happens prac tical scale factor 1% J-3 Cub chosen choice scale results 61-in-span model weighing 37 oz powered 08 hp motor turn ing l05-in-diameter prop 6285 rpm Today modern 05 geared electric flight systems will fit requirement quite well Table gives scaling factors model Surprisingly 05 fits almost ex actly its weight nearly proportion real power plant 65 hp Conti nental engine weighs about 200 lbs 15 gallons fuel aboard weighs another 90 lbs total 290 lbsor 38o Cubs flying weight 05 flight system weighs about 17 ounces 42o gross model weight bad 05 electric dont have calculator square roots Table II gives scaling factors four popular scales Table wingspan Area weight Speed Power Prop RPM J-3 Cub Scale 1 86 FullSlze Scale Factor Model 353 ft1/S 661 184 sq ft uS 563 sq 750 lbuS 237 ounces 80mph 1/V 1/262 30mph 65 hp 1/S5 x 1/V 1/844 0077 hp 72 in1/5 6105 2400 cruiseV 262 6285 Table 11 ScalIng Factore Consanoely Used 5cale inches11A23 Fractionsi Scale 1/8 1/686 1/6 1/4 Ares uS1/641/471/361/16 weight uS 1/512 1/322 1/216 1/64 Speed 1/Vs 1/283 1/262 1/245 1/2 Power 1/5 x 1/V1/1448 1/844 1/529 1/128 Prop Diameter1/5 1/81/686 1/61/4 Prop speed Vi28326224520 Examples Scale models suitable Leisure LT-50 gear motors Leisure LT-50 *6003A 251 geared 7 call Heath Parasol 02 Span313 ft63in Area weight Speed Power Prop RPM Tayloreraft Span Area weight Speed Power Prop RPM 135 sq ft 650 lb 62 mph 25 hp 55 dia 2800 LeIsure LT-5O *603 31 geared 7 call 0 1 36 ft 184 sq ft 900 lbs 96 mph 65 hp 72 2400 Leisure LT-50 *603B 381 geared 7 cell CurtIs RobIn 0 11 ft Span41 ft Area223 sq ft weight1800 lb Speed100 mph Power90 lip Prop104 RPM1400 540 sq us 44oz 25 mph 005 hp 9 6860 63 us 563 sq us 44 oz 37 mph 008 hp 105 in 6288 615 in 502 sq us 56 oz 35 mph 0062 hp 13 3959 Roland Boucher has come up some handy numbers lead us proper scaling procedure avoid head aches come building too large small also keep model weight power within ballpark Electric Scale now flourishing type information needed fact Continued page 138 November1984 135 tnen wriie caii New Model Magic Products Model Magic Epoxy Plus 2 Part 8 Mm Use anywhere two part epoxy used Light weight Sandable Carveable Excellent Gap Filling Non Sagging Superior Strength Sands and carves like basswood! 6 fI oz $895 See dealer IrsI write cal NhJ Model Magic Pociicts Inc =P0 Box 19784 SIPaut MN 55119 715425-1391 TAYLORCRAFT GIANT SCALE 90 WINGSPAN 4 CYCLE 7590 SEND $200 FOR COMPLETE CATALOG OF FINE KITS IKON NWST PO Box 566 Auburn WA 98071 206 941-8248
Edition: Model Aviation - 1984/11
Page Numbers: 44, 45, 134, 135
Radio Control Sport & Aerobatics Ron Van Putte LETTERS got lettersstacks stacks letters Modelers get windy subject wind effects course letters took exception contention airplane unaware steady wind Very few people will write agree opponents dont hesitate notable exception Gene Mathis Daphne AL wrote appreciate effort put wind myth/optical illusion rest true aircraft can feel wind yours truly countless other professional pilots navigators would have spared lot heartburn trying answer essential question whence cometh wind strong does bloweth instance out middle Pacific navigator could have said standard-rate 3600 turn holding airspeed constant will keep eye directional gyro altimeter start climbing diving well know direction wind Based experience can also tell magnitude wind Alas wont work early days high-altitude fly ing jet streams ig norant played havoc navigation because blundered totally unaware Egad navigator redo sumswe cant bucking 150-knot headwind Anyone observing contrail knows stays lined up longitudinal axis aircraft flying athwart jet stream have little fun disbelievers Use long crepe streamer smoke fly straight level course crosswind over troops get variance safety rule demonstration will see although aircraft crabbing streamer smoke will remain perfectly trail position line airplane R VP old pro Bill Winter wrote some thing along ago about oversized fin causing weathervaning know demolishing cherished myth impossible Thanks Gene Impossible tend keep trying Fortunately theres help John Preston great example effects wind August col umn Safety Comes First Check out havent read As mentioned earlier people wrote agree airplane doesnt know steady wind blowing Several argued no such thing steady wind WIND DIRECTION NOWIND TURN -7 F 7 TURN DONE IN WIND C DOWNWIND FIGURE 1 #1 WIND DIRECTION Ron dares wrath readers discussion about effects wind flight models time its about upwind downwind turns RC pilot does under stand winds effects model hes really looking troubleand maybe crashl 44 Model Aviation Fine flight shot Mike Gretz Glen Howards original Ziin Z-50L Sig IMAC Championships model light 6 lbpowered K&B 61 Glen Peoria IL G F NOWIND TURN D c di UPWIND AFIGURE 2 others claimed what observed resulted wind shear layers near ground few puzzled about what observed heavy wind situa tions Most rest genuinely believe airplane feels wind Typical such letters Allan Kass Big Sky MT wrote Im questioning plane may ap pear dive goes downwind ap pear climb goes upwind after flying real thing thousands hours know crosswind take off turn downwind has mushy control feel opposed turn wind control response brisk Ive model planes sink mush back ground first turn after cross wind takeoff downwind flying 22-pound Quarter-Scaler 35-knot wind devil time turning up wind got broadside didnt Continued page 134 EIGHTH ANNUAL [gill [v32]Ufi 1 *1 JANUARY 12 & 13 1985 SEE WITH MAJOR AIRCRAFT BOATS CARS MODEL MODEL MODEL THE LATEST PRODUCTS AND VISIT MANUFACTURERS AND DISTRIBUTORS OF 0 S MODEL ENGINES RADIO CONTROL SYSTEMS MODELING ACCESSORIES PEST 1* WEST *VA IC DISPLAY COMPETITION IN MANY CATEGORIES November 1984 45 Keep cool flight line Solar-powered fan-hat cools forehead evaporating sweat gimmickbut coats $8995 Energy Sciences inc 832 Rockviiie Pike Rockyilie MD 20852 - BN ATNew Turnarouna airpiane Dy U Eagle Inc PO Box 1902 Greenville TX 7540118 named Elliptic Span 70 wing area 865 sq Construction balsa ply Attrac tive model provides alternative CAP-21s Lasers event 3 IUVEWSftA LXHIH UWS GunuII-ILL Y INVI LUI INTERNATIONAL MODELER SHOW OFFICE PO Box 10127 Costa Mesa CA 92627 Ph 714 548-4700 645-88301 TIDEWATER ENGR & MACH Co I4~ PO B0X1135BASTROP LA 71220 MICROMOTORSPHONE 318- 281-2460US DISTRIBUTOR MARINE & CAR ENGINE SPECIALS P-21 Car SE$6500P21 Marine SE$6500P65 Marine $9000 P-21 Car RE$6500P-21 Marine RE$6500P80 Marine $11000 P-21 Buggy SE$6500 P-21 Delta$7500P-45 Marine$7800P90 Marine $14000 AERO ENGINESPECIALS P-21 SE$5000P-45 SE$6000P-80 SE$9000 P21 RE$5500P60 SE$8500P-80 RE$9500 P-40 $6500P60 RE$9000P80 Duct Fan $10000 P-40 SE$5800 P-4b Duct Fan$7500P-65 Duct Fan $9500 TWO NEW MARINE ENGINES P45 Mar-Disc Rotor Valve $8500 P90 Mar-Disc Rotor Valve New Carb $14000 number value enclosed paren theses thickness ordinates directly scalable other exact ordinates can scaled make 12% sec tions charts will correctly 6X X12 Otherwise will 6X, z XXX sections smooth sections superi drag very high RN have somehwat lower CL max far superior high Mach numbers delaying force divergence significantly changing lift moment characteristics severely high subsonic speeds have rather large negative pitching mo ments normally used fairly low CL moment can designed out part combining swept wings washout original 1series sections 16-XXX shapes used propellers because better performance high Mach numbers commonly called 16- series airfoils RN about 12 million mini mum profile drag sections will about same four- five-digit sections same thickness Below suffer earlier laminar separa tion higher drag shapes down RN about 70 thousand below drag airfoils becomes mostly pressure drag due laminar separation no reason use sec tions model application other scale fidelity make nice flying wings however relatively sharp leading edges have caused no problems variety scratchbuilt planes conclude hoped tables can future practical use comments have clear interest information condensed primarily Theory Wing Sections Abbott von Doenhoff RC AerobaticslVan Putte Continued page 45 want go remainder turn almost like sailboat irons Whyif doesnt know wind blowing think virtually questions contained Allan Kass letter lot other letters received can answered considering frame ref erence observer fly ing RC usually standing ground attempting make air plane fly maneuvers prescribed man ner regardless wind blowing may have heard about danger ous downwind turn downwind turn 1800 turn started airplane heading downwind Usually turn starts out right little past halfway around airplane stalls out crashes Basically its because pilot crashed wind con tributing factor pilots faulty understanding effects wind causes stall crash Figure 1 shows top view l8O turn both steady wind wind downwind assumed control inputs same both cases effect wind can have move ground track airplane downwind relative no wind track movement ground track function fast wind blowing long has since turn started hash marks respective turns equal time crements Since effect wind constant its effect ground track constant additive other words points B B certain distance apart points C C will twice far apart points D D will three times far apart looks pretty wild doesnt Well pilot trying perform turn looks like no-wind gets upset starts go astray course stand ard correction increase roll angle pull Up elevator track still doesnt look right pilot keeps creasing roll angle pulling Up elevator Surpriselthe airplane just stalled out Its known accelerated stall stall occurs airplane puffing lot Gs isnt like normal stall Since airplane high speed stall happens very abruptly airplane often crashes before pilot can anything way take another look track airplane wind does look like reluctant come around wind until last part turn doesnt no magic involved observers view turn appears indicate strange things happening because observer fixed airplane moving relative wind youd like another thrill take look Figure 2 airplane starts 180 0turn heading upwind comparison same turn shown no-wind situation identical control input Again theres no magic involved fixed observer airplane again appears doing strange things No wonder beginners often get shook make kind turn airplane appears jump back Strange things happen loops too Ill cover later column Thats enough effects wind month heard about costly crash think would valuable lesson us planning change RC equipment new frequencies seems flier took equipment repairman routine maintenance have frequency changed got back assumed equip ment top shape new fre quency bill didnt say specifically what done equipment went contest got shot down because repairman never changed fre quency fault dont know have frequency change future Ill make sure bill dicates what done mystery plane appeared September issue El Gringo 60-size Slicker according Bill Dennis Amarillo TX Bill used trike gear 40-size Slicker place 1972 Canadian Nats Rebel Rally Jacksonville FL way Bill would like modelers interested plans old Stormer IV know has available $12 set Write Sky Fllte Models 20 Windsor Amarillo TX 79106 being written just before 84 134 Model Aviation Model Magic Filler Quick setting Light weight Non shrinking Fillets Gap filling Ding repair See dealer urst Model Magic Products Model Magic Products PO Box 7784St Paul Minn 55119 715 425-1397 $595 Retail 8 fI oz Adhesion Balsa Foam Fiberglass Strength Flexing Spreading Fuel Resistance Sanding Hardness Finishing Shelf Life Tint Acceptance Water Resistance Comparison Chart Model Magic Excellent Product X Very Poor a Good As medium balsa As Hard Balsa Any fish/covering till used up Excellent Soft balsa Soft balsa ail Spoils i 5lmo Very Poor Test methods arid data avalable request care enough fill very best uisast Model Magc Fler Circus Magic FiNer Nats start Id love cant Nats RC Pattern coverage will handled Steve McCann Pete Callas members National Society Radio Controlled Aerobatics Pete Steve co-District 7 Vice Presidents NSRCA jointly author District 7 submission K-Factor newsletter NSRCA always look forward K-Factor articles know real treat Nats coverage Ron Van Putte 111 Sleepy Oaks Rd Ft Walton Beach FL 32S48 RO ScalelWlschers Continued page 47 reduced real planes power 1/S3 weight factor l/V speed factor Using Y-scale 65 hp Piper Cub example power re quired would 65 p 65 hp Continental engine turned 72-in-diameter prop 2400 rpm 18-in scale-size prop used must turn faster square root scale fac tor 2400 x -VT rpm example A-scale plane given keep math easy results however 108-in-span plane weighing 12 lbsnot exactly schoolyard flier Lets see what happens prac tical scale factor 1% J-3 Cub chosen choice scale results 61-in-span model weighing 37 oz powered 08 hp motor turn ing l05-in-diameter prop 6285 rpm Today modern 05 geared electric flight systems will fit requirement quite well Table gives scaling factors model Surprisingly 05 fits almost ex actly its weight nearly proportion real power plant 65 hp Conti nental engine weighs about 200 lbs 15 gallons fuel aboard weighs another 90 lbs total 290 lbsor 38o Cubs flying weight 05 flight system weighs about 17 ounces 42o gross model weight bad 05 electric dont have calculator square roots Table II gives scaling factors four popular scales Table wingspan Area weight Speed Power Prop RPM J-3 Cub Scale 1 86 FullSlze Scale Factor Model 353 ft1/S 661 184 sq ft uS 563 sq 750 lbuS 237 ounces 80mph 1/V 1/262 30mph 65 hp 1/S5 x 1/V 1/844 0077 hp 72 in1/5 6105 2400 cruiseV 262 6285 Table 11 ScalIng Factore Consanoely Used 5cale inches11A23 Fractionsi Scale 1/8 1/686 1/6 1/4 Ares uS1/641/471/361/16 weight uS 1/512 1/322 1/216 1/64 Speed 1/Vs 1/283 1/262 1/245 1/2 Power 1/5 x 1/V1/1448 1/844 1/529 1/128 Prop Diameter1/5 1/81/686 1/61/4 Prop speed Vi28326224520 Examples Scale models suitable Leisure LT-50 gear motors Leisure LT-50 *6003A 251 geared 7 call Heath Parasol 02 Span313 ft63in Area weight Speed Power Prop RPM Tayloreraft Span Area weight Speed Power Prop RPM 135 sq ft 650 lb 62 mph 25 hp 55 dia 2800 LeIsure LT-5O *603 31 geared 7 call 0 1 36 ft 184 sq ft 900 lbs 96 mph 65 hp 72 2400 Leisure LT-50 *603B 381 geared 7 cell CurtIs RobIn 0 11 ft Span41 ft Area223 sq ft weight1800 lb Speed100 mph Power90 lip Prop104 RPM1400 540 sq us 44oz 25 mph 005 hp 9 6860 63 us 563 sq us 44 oz 37 mph 008 hp 105 in 6288 615 in 502 sq us 56 oz 35 mph 0062 hp 13 3959 Roland Boucher has come up some handy numbers lead us proper scaling procedure avoid head aches come building too large small also keep model weight power within ballpark Electric Scale now flourishing type information needed fact Continued page 138 November1984 135 tnen wriie caii New Model Magic Products Model Magic Epoxy Plus 2 Part 8 Mm Use anywhere two part epoxy used Light weight Sandable Carveable Excellent Gap Filling Non Sagging Superior Strength Sands and carves like basswood! 6 fI oz $895 See dealer IrsI write cal NhJ Model Magic Pociicts Inc =P0 Box 19784 SIPaut MN 55119 715425-1391 TAYLORCRAFT GIANT SCALE 90 WINGSPAN 4 CYCLE 7590 SEND $200 FOR COMPLETE CATALOG OF FINE KITS IKON NWST PO Box 566 Auburn WA 98071 206 941-8248
Edition: Model Aviation - 1984/11
Page Numbers: 44, 45, 134, 135
Radio Control Sport & Aerobatics Ron Van Putte LETTERS got lettersstacks stacks letters Modelers get windy subject wind effects course letters took exception contention airplane unaware steady wind Very few people will write agree opponents dont hesitate notable exception Gene Mathis Daphne AL wrote appreciate effort put wind myth/optical illusion rest true aircraft can feel wind yours truly countless other professional pilots navigators would have spared lot heartburn trying answer essential question whence cometh wind strong does bloweth instance out middle Pacific navigator could have said standard-rate 3600 turn holding airspeed constant will keep eye directional gyro altimeter start climbing diving well know direction wind Based experience can also tell magnitude wind Alas wont work early days high-altitude fly ing jet streams ig norant played havoc navigation because blundered totally unaware Egad navigator redo sumswe cant bucking 150-knot headwind Anyone observing contrail knows stays lined up longitudinal axis aircraft flying athwart jet stream have little fun disbelievers Use long crepe streamer smoke fly straight level course crosswind over troops get variance safety rule demonstration will see although aircraft crabbing streamer smoke will remain perfectly trail position line airplane R VP old pro Bill Winter wrote some thing along ago about oversized fin causing weathervaning know demolishing cherished myth impossible Thanks Gene Impossible tend keep trying Fortunately theres help John Preston great example effects wind August col umn Safety Comes First Check out havent read As mentioned earlier people wrote agree airplane doesnt know steady wind blowing Several argued no such thing steady wind WIND DIRECTION NOWIND TURN -7 F 7 TURN DONE IN WIND C DOWNWIND FIGURE 1 #1 WIND DIRECTION Ron dares wrath readers discussion about effects wind flight models time its about upwind downwind turns RC pilot does under stand winds effects model hes really looking troubleand maybe crashl 44 Model Aviation Fine flight shot Mike Gretz Glen Howards original Ziin Z-50L Sig IMAC Championships model light 6 lbpowered K&B 61 Glen Peoria IL G F NOWIND TURN D c di UPWIND AFIGURE 2 others claimed what observed resulted wind shear layers near ground few puzzled about what observed heavy wind situa tions Most rest genuinely believe airplane feels wind Typical such letters Allan Kass Big Sky MT wrote Im questioning plane may ap pear dive goes downwind ap pear climb goes upwind after flying real thing thousands hours know crosswind take off turn downwind has mushy control feel opposed turn wind control response brisk Ive model planes sink mush back ground first turn after cross wind takeoff downwind flying 22-pound Quarter-Scaler 35-knot wind devil time turning up wind got broadside didnt Continued page 134 EIGHTH ANNUAL [gill [v32]Ufi 1 *1 JANUARY 12 & 13 1985 SEE WITH MAJOR AIRCRAFT BOATS CARS MODEL MODEL MODEL THE LATEST PRODUCTS AND VISIT MANUFACTURERS AND DISTRIBUTORS OF 0 S MODEL ENGINES RADIO CONTROL SYSTEMS MODELING ACCESSORIES PEST 1* WEST *VA IC DISPLAY COMPETITION IN MANY CATEGORIES November 1984 45 Keep cool flight line Solar-powered fan-hat cools forehead evaporating sweat gimmickbut coats $8995 Energy Sciences inc 832 Rockviiie Pike Rockyilie MD 20852 - BN ATNew Turnarouna airpiane Dy U Eagle Inc PO Box 1902 Greenville TX 7540118 named Elliptic Span 70 wing area 865 sq Construction balsa ply Attrac tive model provides alternative CAP-21s Lasers event 3 IUVEWSftA LXHIH UWS GunuII-ILL Y INVI LUI INTERNATIONAL MODELER SHOW OFFICE PO Box 10127 Costa Mesa CA 92627 Ph 714 548-4700 645-88301 TIDEWATER ENGR & MACH Co I4~ PO B0X1135BASTROP LA 71220 MICROMOTORSPHONE 318- 281-2460US DISTRIBUTOR MARINE & CAR ENGINE SPECIALS P-21 Car SE$6500P21 Marine SE$6500P65 Marine $9000 P-21 Car RE$6500P-21 Marine RE$6500P80 Marine $11000 P-21 Buggy SE$6500 P-21 Delta$7500P-45 Marine$7800P90 Marine $14000 AERO ENGINESPECIALS P-21 SE$5000P-45 SE$6000P-80 SE$9000 P21 RE$5500P60 SE$8500P-80 RE$9500 P-40 $6500P60 RE$9000P80 Duct Fan $10000 P-40 SE$5800 P-4b Duct Fan$7500P-65 Duct Fan $9500 TWO NEW MARINE ENGINES P45 Mar-Disc Rotor Valve $8500 P90 Mar-Disc Rotor Valve New Carb $14000 number value enclosed paren theses thickness ordinates directly scalable other exact ordinates can scaled make 12% sec tions charts will correctly 6X X12 Otherwise will 6X, z XXX sections smooth sections superi drag very high RN have somehwat lower CL max far superior high Mach numbers delaying force divergence significantly changing lift moment characteristics severely high subsonic speeds have rather large negative pitching mo ments normally used fairly low CL moment can designed out part combining swept wings washout original 1series sections 16-XXX shapes used propellers because better performance high Mach numbers commonly called 16- series airfoils RN about 12 million mini mum profile drag sections will about same four- five-digit sections same thickness Below suffer earlier laminar separa tion higher drag shapes down RN about 70 thousand below drag airfoils becomes mostly pressure drag due laminar separation no reason use sec tions model application other scale fidelity make nice flying wings however relatively sharp leading edges have caused no problems variety scratchbuilt planes conclude hoped tables can future practical use comments have clear interest information condensed primarily Theory Wing Sections Abbott von Doenhoff RC AerobaticslVan Putte Continued page 45 want go remainder turn almost like sailboat irons Whyif doesnt know wind blowing think virtually questions contained Allan Kass letter lot other letters received can answered considering frame ref erence observer fly ing RC usually standing ground attempting make air plane fly maneuvers prescribed man ner regardless wind blowing may have heard about danger ous downwind turn downwind turn 1800 turn started airplane heading downwind Usually turn starts out right little past halfway around airplane stalls out crashes Basically its because pilot crashed wind con tributing factor pilots faulty understanding effects wind causes stall crash Figure 1 shows top view l8O turn both steady wind wind downwind assumed control inputs same both cases effect wind can have move ground track airplane downwind relative no wind track movement ground track function fast wind blowing long has since turn started hash marks respective turns equal time crements Since effect wind constant its effect ground track constant additive other words points B B certain distance apart points C C will twice far apart points D D will three times far apart looks pretty wild doesnt Well pilot trying perform turn looks like no-wind gets upset starts go astray course stand ard correction increase roll angle pull Up elevator track still doesnt look right pilot keeps creasing roll angle pulling Up elevator Surpriselthe airplane just stalled out Its known accelerated stall stall occurs airplane puffing lot Gs isnt like normal stall Since airplane high speed stall happens very abruptly airplane often crashes before pilot can anything way take another look track airplane wind does look like reluctant come around wind until last part turn doesnt no magic involved observers view turn appears indicate strange things happening because observer fixed airplane moving relative wind youd like another thrill take look Figure 2 airplane starts 180 0turn heading upwind comparison same turn shown no-wind situation identical control input Again theres no magic involved fixed observer airplane again appears doing strange things No wonder beginners often get shook make kind turn airplane appears jump back Strange things happen loops too Ill cover later column Thats enough effects wind month heard about costly crash think would valuable lesson us planning change RC equipment new frequencies seems flier took equipment repairman routine maintenance have frequency changed got back assumed equip ment top shape new fre quency bill didnt say specifically what done equipment went contest got shot down because repairman never changed fre quency fault dont know have frequency change future Ill make sure bill dicates what done mystery plane appeared September issue El Gringo 60-size Slicker according Bill Dennis Amarillo TX Bill used trike gear 40-size Slicker place 1972 Canadian Nats Rebel Rally Jacksonville FL way Bill would like modelers interested plans old Stormer IV know has available $12 set Write Sky Fllte Models 20 Windsor Amarillo TX 79106 being written just before 84 134 Model Aviation Model Magic Filler Quick setting Light weight Non shrinking Fillets Gap filling Ding repair See dealer urst Model Magic Products Model Magic Products PO Box 7784St Paul Minn 55119 715 425-1397 $595 Retail 8 fI oz Adhesion Balsa Foam Fiberglass Strength Flexing Spreading Fuel Resistance Sanding Hardness Finishing Shelf Life Tint Acceptance Water Resistance Comparison Chart Model Magic Excellent Product X Very Poor a Good As medium balsa As Hard Balsa Any fish/covering till used up Excellent Soft balsa Soft balsa ail Spoils i 5lmo Very Poor Test methods arid data avalable request care enough fill very best uisast Model Magc Fler Circus Magic FiNer Nats start Id love cant Nats RC Pattern coverage will handled Steve McCann Pete Callas members National Society Radio Controlled Aerobatics Pete Steve co-District 7 Vice Presidents NSRCA jointly author District 7 submission K-Factor newsletter NSRCA always look forward K-Factor articles know real treat Nats coverage Ron Van Putte 111 Sleepy Oaks Rd Ft Walton Beach FL 32S48 RO ScalelWlschers Continued page 47 reduced real planes power 1/S3 weight factor l/V speed factor Using Y-scale 65 hp Piper Cub example power re quired would 65 p 65 hp Continental engine turned 72-in-diameter prop 2400 rpm 18-in scale-size prop used must turn faster square root scale fac tor 2400 x -VT rpm example A-scale plane given keep math easy results however 108-in-span plane weighing 12 lbsnot exactly schoolyard flier Lets see what happens prac tical scale factor 1% J-3 Cub chosen choice scale results 61-in-span model weighing 37 oz powered 08 hp motor turn ing l05-in-diameter prop 6285 rpm Today modern 05 geared electric flight systems will fit requirement quite well Table gives scaling factors model Surprisingly 05 fits almost ex actly its weight nearly proportion real power plant 65 hp Conti nental engine weighs about 200 lbs 15 gallons fuel aboard weighs another 90 lbs total 290 lbsor 38o Cubs flying weight 05 flight system weighs about 17 ounces 42o gross model weight bad 05 electric dont have calculator square roots Table II gives scaling factors four popular scales Table wingspan Area weight Speed Power Prop RPM J-3 Cub Scale 1 86 FullSlze Scale Factor Model 353 ft1/S 661 184 sq ft uS 563 sq 750 lbuS 237 ounces 80mph 1/V 1/262 30mph 65 hp 1/S5 x 1/V 1/844 0077 hp 72 in1/5 6105 2400 cruiseV 262 6285 Table 11 ScalIng Factore Consanoely Used 5cale inches11A23 Fractionsi Scale 1/8 1/686 1/6 1/4 Ares uS1/641/471/361/16 weight uS 1/512 1/322 1/216 1/64 Speed 1/Vs 1/283 1/262 1/245 1/2 Power 1/5 x 1/V1/1448 1/844 1/529 1/128 Prop Diameter1/5 1/81/686 1/61/4 Prop speed Vi28326224520 Examples Scale models suitable Leisure LT-50 gear motors Leisure LT-50 *6003A 251 geared 7 call Heath Parasol 02 Span313 ft63in Area weight Speed Power Prop RPM Tayloreraft Span Area weight Speed Power Prop RPM 135 sq ft 650 lb 62 mph 25 hp 55 dia 2800 LeIsure LT-5O *603 31 geared 7 call 0 1 36 ft 184 sq ft 900 lbs 96 mph 65 hp 72 2400 Leisure LT-50 *603B 381 geared 7 cell CurtIs RobIn 0 11 ft Span41 ft Area223 sq ft weight1800 lb Speed100 mph Power90 lip Prop104 RPM1400 540 sq us 44oz 25 mph 005 hp 9 6860 63 us 563 sq us 44 oz 37 mph 008 hp 105 in 6288 615 in 502 sq us 56 oz 35 mph 0062 hp 13 3959 Roland Boucher has come up some handy numbers lead us proper scaling procedure avoid head aches come building too large small also keep model weight power within ballpark Electric Scale now flourishing type information needed fact Continued page 138 November1984 135 tnen wriie caii New Model Magic Products Model Magic Epoxy Plus 2 Part 8 Mm Use anywhere two part epoxy used Light weight Sandable Carveable Excellent Gap Filling Non Sagging Superior Strength Sands and carves like basswood! 6 fI oz $895 See dealer IrsI write cal NhJ Model Magic Pociicts Inc =P0 Box 19784 SIPaut MN 55119 715425-1391 TAYLORCRAFT GIANT SCALE 90 WINGSPAN 4 CYCLE 7590 SEND $200 FOR COMPLETE CATALOG OF FINE KITS IKON NWST PO Box 566 Auburn WA 98071 206 941-8248
Edition: Model Aviation - 1984/11
Page Numbers: 44, 45, 134, 135
Radio Control Sport & Aerobatics Ron Van Putte LETTERS got lettersstacks stacks letters Modelers get windy subject wind effects course letters took exception contention airplane unaware steady wind Very few people will write agree opponents dont hesitate notable exception Gene Mathis Daphne AL wrote appreciate effort put wind myth/optical illusion rest true aircraft can feel wind yours truly countless other professional pilots navigators would have spared lot heartburn trying answer essential question whence cometh wind strong does bloweth instance out middle Pacific navigator could have said standard-rate 3600 turn holding airspeed constant will keep eye directional gyro altimeter start climbing diving well know direction wind Based experience can also tell magnitude wind Alas wont work early days high-altitude fly ing jet streams ig norant played havoc navigation because blundered totally unaware Egad navigator redo sumswe cant bucking 150-knot headwind Anyone observing contrail knows stays lined up longitudinal axis aircraft flying athwart jet stream have little fun disbelievers Use long crepe streamer smoke fly straight level course crosswind over troops get variance safety rule demonstration will see although aircraft crabbing streamer smoke will remain perfectly trail position line airplane R VP old pro Bill Winter wrote some thing along ago about oversized fin causing weathervaning know demolishing cherished myth impossible Thanks Gene Impossible tend keep trying Fortunately theres help John Preston great example effects wind August col umn Safety Comes First Check out havent read As mentioned earlier people wrote agree airplane doesnt know steady wind blowing Several argued no such thing steady wind WIND DIRECTION NOWIND TURN -7 F 7 TURN DONE IN WIND C DOWNWIND FIGURE 1 #1 WIND DIRECTION Ron dares wrath readers discussion about effects wind flight models time its about upwind downwind turns RC pilot does under stand winds effects model hes really looking troubleand maybe crashl 44 Model Aviation Fine flight shot Mike Gretz Glen Howards original Ziin Z-50L Sig IMAC Championships model light 6 lbpowered K&B 61 Glen Peoria IL G F NOWIND TURN D c di UPWIND AFIGURE 2 others claimed what observed resulted wind shear layers near ground few puzzled about what observed heavy wind situa tions Most rest genuinely believe airplane feels wind Typical such letters Allan Kass Big Sky MT wrote Im questioning plane may ap pear dive goes downwind ap pear climb goes upwind after flying real thing thousands hours know crosswind take off turn downwind has mushy control feel opposed turn wind control response brisk Ive model planes sink mush back ground first turn after cross wind takeoff downwind flying 22-pound Quarter-Scaler 35-knot wind devil time turning up wind got broadside didnt Continued page 134 EIGHTH ANNUAL [gill [v32]Ufi 1 *1 JANUARY 12 & 13 1985 SEE WITH MAJOR AIRCRAFT BOATS CARS MODEL MODEL MODEL THE LATEST PRODUCTS AND VISIT MANUFACTURERS AND DISTRIBUTORS OF 0 S MODEL ENGINES RADIO CONTROL SYSTEMS MODELING ACCESSORIES PEST 1* WEST *VA IC DISPLAY COMPETITION IN MANY CATEGORIES November 1984 45 Keep cool flight line Solar-powered fan-hat cools forehead evaporating sweat gimmickbut coats $8995 Energy Sciences inc 832 Rockviiie Pike Rockyilie MD 20852 - BN ATNew Turnarouna airpiane Dy U Eagle Inc PO Box 1902 Greenville TX 7540118 named Elliptic Span 70 wing area 865 sq Construction balsa ply Attrac tive model provides alternative CAP-21s Lasers event 3 IUVEWSftA LXHIH UWS GunuII-ILL Y INVI LUI INTERNATIONAL MODELER SHOW OFFICE PO Box 10127 Costa Mesa CA 92627 Ph 714 548-4700 645-88301 TIDEWATER ENGR & MACH Co I4~ PO B0X1135BASTROP LA 71220 MICROMOTORSPHONE 318- 281-2460US DISTRIBUTOR MARINE & CAR ENGINE SPECIALS P-21 Car SE$6500P21 Marine SE$6500P65 Marine $9000 P-21 Car RE$6500P-21 Marine RE$6500P80 Marine $11000 P-21 Buggy SE$6500 P-21 Delta$7500P-45 Marine$7800P90 Marine $14000 AERO ENGINESPECIALS P-21 SE$5000P-45 SE$6000P-80 SE$9000 P21 RE$5500P60 SE$8500P-80 RE$9500 P-40 $6500P60 RE$9000P80 Duct Fan $10000 P-40 SE$5800 P-4b Duct Fan$7500P-65 Duct Fan $9500 TWO NEW MARINE ENGINES P45 Mar-Disc Rotor Valve $8500 P90 Mar-Disc Rotor Valve New Carb $14000 number value enclosed paren theses thickness ordinates directly scalable other exact ordinates can scaled make 12% sec tions charts will correctly 6X X12 Otherwise will 6X, z XXX sections smooth sections superi drag very high RN have somehwat lower CL max far superior high Mach numbers delaying force divergence significantly changing lift moment characteristics severely high subsonic speeds have rather large negative pitching mo ments normally used fairly low CL moment can designed out part combining swept wings washout original 1series sections 16-XXX shapes used propellers because better performance high Mach numbers commonly called 16- series airfoils RN about 12 million mini mum profile drag sections will about same four- five-digit sections same thickness Below suffer earlier laminar separa tion higher drag shapes down RN about 70 thousand below drag airfoils becomes mostly pressure drag due laminar separation no reason use sec tions model application other scale fidelity make nice flying wings however relatively sharp leading edges have caused no problems variety scratchbuilt planes conclude hoped tables can future practical use comments have clear interest information condensed primarily Theory Wing Sections Abbott von Doenhoff RC AerobaticslVan Putte Continued page 45 want go remainder turn almost like sailboat irons Whyif doesnt know wind blowing think virtually questions contained Allan Kass letter lot other letters received can answered considering frame ref erence observer fly ing RC usually standing ground attempting make air plane fly maneuvers prescribed man ner regardless wind blowing may have heard about danger ous downwind turn downwind turn 1800 turn started airplane heading downwind Usually turn starts out right little past halfway around airplane stalls out crashes Basically its because pilot crashed wind con tributing factor pilots faulty understanding effects wind causes stall crash Figure 1 shows top view l8O turn both steady wind wind downwind assumed control inputs same both cases effect wind can have move ground track airplane downwind relative no wind track movement ground track function fast wind blowing long has since turn started hash marks respective turns equal time crements Since effect wind constant its effect ground track constant additive other words points B B certain distance apart points C C will twice far apart points D D will three times far apart looks pretty wild doesnt Well pilot trying perform turn looks like no-wind gets upset starts go astray course stand ard correction increase roll angle pull Up elevator track still doesnt look right pilot keeps creasing roll angle pulling Up elevator Surpriselthe airplane just stalled out Its known accelerated stall stall occurs airplane puffing lot Gs isnt like normal stall Since airplane high speed stall happens very abruptly airplane often crashes before pilot can anything way take another look track airplane wind does look like reluctant come around wind until last part turn doesnt no magic involved observers view turn appears indicate strange things happening because observer fixed airplane moving relative wind youd like another thrill take look Figure 2 airplane starts 180 0turn heading upwind comparison same turn shown no-wind situation identical control input Again theres no magic involved fixed observer airplane again appears doing strange things No wonder beginners often get shook make kind turn airplane appears jump back Strange things happen loops too Ill cover later column Thats enough effects wind month heard about costly crash think would valuable lesson us planning change RC equipment new frequencies seems flier took equipment repairman routine maintenance have frequency changed got back assumed equip ment top shape new fre quency bill didnt say specifically what done equipment went contest got shot down because repairman never changed fre quency fault dont know have frequency change future Ill make sure bill dicates what done mystery plane appeared September issue El Gringo 60-size Slicker according Bill Dennis Amarillo TX Bill used trike gear 40-size Slicker place 1972 Canadian Nats Rebel Rally Jacksonville FL way Bill would like modelers interested plans old Stormer IV know has available $12 set Write Sky Fllte Models 20 Windsor Amarillo TX 79106 being written just before 84 134 Model Aviation Model Magic Filler Quick setting Light weight Non shrinking Fillets Gap filling Ding repair See dealer urst Model Magic Products Model Magic Products PO Box 7784St Paul Minn 55119 715 425-1397 $595 Retail 8 fI oz Adhesion Balsa Foam Fiberglass Strength Flexing Spreading Fuel Resistance Sanding Hardness Finishing Shelf Life Tint Acceptance Water Resistance Comparison Chart Model Magic Excellent Product X Very Poor a Good As medium balsa As Hard Balsa Any fish/covering till used up Excellent Soft balsa Soft balsa ail Spoils i 5lmo Very Poor Test methods arid data avalable request care enough fill very best uisast Model Magc Fler Circus Magic FiNer Nats start Id love cant Nats RC Pattern coverage will handled Steve McCann Pete Callas members National Society Radio Controlled Aerobatics Pete Steve co-District 7 Vice Presidents NSRCA jointly author District 7 submission K-Factor newsletter NSRCA always look forward K-Factor articles know real treat Nats coverage Ron Van Putte 111 Sleepy Oaks Rd Ft Walton Beach FL 32S48 RO ScalelWlschers Continued page 47 reduced real planes power 1/S3 weight factor l/V speed factor Using Y-scale 65 hp Piper Cub example power re quired would 65 p 65 hp Continental engine turned 72-in-diameter prop 2400 rpm 18-in scale-size prop used must turn faster square root scale fac tor 2400 x -VT rpm example A-scale plane given keep math easy results however 108-in-span plane weighing 12 lbsnot exactly schoolyard flier Lets see what happens prac tical scale factor 1% J-3 Cub chosen choice scale results 61-in-span model weighing 37 oz powered 08 hp motor turn ing l05-in-diameter prop 6285 rpm Today modern 05 geared electric flight systems will fit requirement quite well Table gives scaling factors model Surprisingly 05 fits almost ex actly its weight nearly proportion real power plant 65 hp Conti nental engine weighs about 200 lbs 15 gallons fuel aboard weighs another 90 lbs total 290 lbsor 38o Cubs flying weight 05 flight system weighs about 17 ounces 42o gross model weight bad 05 electric dont have calculator square roots Table II gives scaling factors four popular scales Table wingspan Area weight Speed Power Prop RPM J-3 Cub Scale 1 86 FullSlze Scale Factor Model 353 ft1/S 661 184 sq ft uS 563 sq 750 lbuS 237 ounces 80mph 1/V 1/262 30mph 65 hp 1/S5 x 1/V 1/844 0077 hp 72 in1/5 6105 2400 cruiseV 262 6285 Table 11 ScalIng Factore Consanoely Used 5cale inches11A23 Fractionsi Scale 1/8 1/686 1/6 1/4 Ares uS1/641/471/361/16 weight uS 1/512 1/322 1/216 1/64 Speed 1/Vs 1/283 1/262 1/245 1/2 Power 1/5 x 1/V1/1448 1/844 1/529 1/128 Prop Diameter1/5 1/81/686 1/61/4 Prop speed Vi28326224520 Examples Scale models suitable Leisure LT-50 gear motors Leisure LT-50 *6003A 251 geared 7 call Heath Parasol 02 Span313 ft63in Area weight Speed Power Prop RPM Tayloreraft Span Area weight Speed Power Prop RPM 135 sq ft 650 lb 62 mph 25 hp 55 dia 2800 LeIsure LT-5O *603 31 geared 7 call 0 1 36 ft 184 sq ft 900 lbs 96 mph 65 hp 72 2400 Leisure LT-50 *603B 381 geared 7 cell CurtIs RobIn 0 11 ft Span41 ft Area223 sq ft weight1800 lb Speed100 mph Power90 lip Prop104 RPM1400 540 sq us 44oz 25 mph 005 hp 9 6860 63 us 563 sq us 44 oz 37 mph 008 hp 105 in 6288 615 in 502 sq us 56 oz 35 mph 0062 hp 13 3959 Roland Boucher has come up some handy numbers lead us proper scaling procedure avoid head aches come building too large small also keep model weight power within ballpark Electric Scale now flourishing type information needed fact Continued page 138 November1984 135 tnen wriie caii New Model Magic Products Model Magic Epoxy Plus 2 Part 8 Mm Use anywhere two part epoxy used Light weight Sandable Carveable Excellent Gap Filling Non Sagging Superior Strength Sands and carves like basswood! 6 fI oz $895 See dealer IrsI write cal NhJ Model Magic Pociicts Inc =P0 Box 19784 SIPaut MN 55119 715425-1391 TAYLORCRAFT GIANT SCALE 90 WINGSPAN 4 CYCLE 7590 SEND $200 FOR COMPLETE CATALOG OF FINE KITS IKON NWST PO Box 566 Auburn WA 98071 206 941-8248