MODEL AIRPLANES Its easy think says author father-andson test program yielded some interesting results 28 Model Aviation f Raskiri explaining term aspect ratio then-nine-year-old son Aza taking part ages-old tradition passing knowledge generation next gave him simple example rectangular wing aspect ratio span divided chord wing foot span foot chord would have aspect ratio . interrupted Right said span four feet . aspect ratio would befour said Aza showed him notate aspect ratios 11 41 talked about bigger wings could carry weightor same weight larger wing could fly slowly smaller wings Aza has flying lot model airplanes made sense him really tiny wing added airplane would have fly very fast stay up Right said pleased observation showed him picture F-104 its tiny wings goes very fast Aza asked question trying lead him think about What difference does aspect ratio make way airplane flies full-size airplanes answered higher aspect ratios make efficient can go farther less fuel example What kind airplanes have very high aspect ratios Aza has plastic models hanging ceiling home including some sailplanes Gliders said can go long ways fuel use thermais climb So dont people just make airplanes large aspect ratios What would look like asked wings would long skinny replied what problems would cause would flex too much especially high speeds would hard put hangars youd need very long ramp get airport would have left subject wanted know did say full-size airplanes Isnt true models too Well extemporized things bit complicated Its easy find out said Aza Lets just make two modelsone high aspect ratio low aspect ratio everything else same see flies better Azas proposal sounded reasonable no finer way get truth Wings quarter-chords aligned Wings centers same line June1997 29 Area4 sq in Span 8 Chord 05 Aspect Ratio 16 Area 4 sq Span 4 Chord 1 Aspect Ratio 4 Area 4 sq Span 2 Chord 2 Aspect Ratio 1 -U 0 well-designed experiment didnt have answer him since make chord wing small becomes less efficient Reynolds number effects works against gains increasing aspect ratio unlike full-scale airplanes Reynolds number effects usually important thought try explain Aza would bit much hed have take lot faith Aza could see test models would have identical could make changed aspect ratio would have keep area constant Aza studied area its relationship multiplication enough mathematics find rectangles same area different aspect ratios decided small simple balsa models wing area four square inches aspect ratio 11 wing would two inches two inches square wing suggested aspect ratio 161 soon drawn rectangle 1/2 inch eight inches long thin wing Another easy span four inches chord inch 41 aspect ratio suggested wing chord 11/2 inches think quite figure span came up number wrong answers before figuring out surprising him correct 10 2/3 inches never built last wing turned out decided wings could conveniently made A2 balsa consistency would just cut pieces square-edged round themjust like F North Pacific Guillow gliders often fly didnt discuss logically no difference between asking about effect aspect ratio effect span experiment could equally well describe wings going build having same areafour square inches spans two four eight inches found hobby shop bought sheet A2 x 2 x 36 balsa wings tail surfaces 1/8 x stick make fuselages little bottle cyanoacrylate CyA glue purchased assemble models stabilizer would 25% area wingour familys standard formula simple gliders made square inch Aza soon sketched out x 2 rectangle chose use twin-fin design since fins would stiffen stabilizer would very easy align fins /2 inch chord 3/4 inch height Aza already knew about using decalage give model pitch stability wanted some way make sure airplanes same amount So just built fuselage shape Three stabilizer/fin assemblies built attached bottom fuselage sticks using square assure straight line ruled across center stabilizer assured centered Things going well until asked should attach wings Aerodynamics texts tell us rectangular flat wing acts though its lift generated line /4 way front airfoil lifting line airfoil one-inch chord behind leading edge way build airplanes put quarter-chord points wings same position fuselage would change weight distribution models keep weight distribution same airfoils would have have centers same position fuselage fun see Aza ponder over concept lifting line something hadnt run before asked could demonstrate him couldnt think easy way demonstrate lifting-line concept Continued page 37 30 Model Aviation wing airfoil 62% 41 wing airfoil 31% 11 wing airfoil 15% End views three wings showing airfoils used scaled equal chord length wing awing b wing c wings b have same total dihedral wings c have same dihedral angle TestinglRaskin Continued page 30 seffled putting centers wings same place Pure experiments give clean answers very hard come aerodynamics business about proper location wings different aspect ratio fine example Airplanes quite sensitive position wing certainly unclear what right way proceed case built models anyway went backyard test fly rise some five feet Aza toss soft grass cushion landings nearly morning windless Dandelion fluffone favorite wind indicatorsdropped straight down two low-aspect-ratio airplanes flew well 161 model bit unstable decided some dihedral would beneficial next question much dihedral Should use same angle dihedral raise wingtips same distance pointed out raising same distance would make angle greater shorter wingssomething immediately clear Aza What does mean two wings different spans aspect ratios have same amount dihedral Again made arbitrary decision keep angle same choice hard justify physically assuming lift generated wing proportional its area like third-graders Aza isnt quite up trigonometry vector representation forces needed explanation trimming however able get 161 fly stably never added dihedral Another difference between models June1997 37 LIGHTING SYSTEMS THE ORIGINALS. Still Best RAM 01Adj Flash Nay Lights 9V NEW 94 spanWI wing light conn$2995 RAM 02Strobe Light 9V adjustable flash rate1995 RAM 03Landing Li9hts 48V receiver controlled3995 RAM 04Mars Rotating Beacon 9V adjustable rate1995 RAM 06 Sky Lights 18 Li9ht Set 72-9V 94 best way fly night 2995 RAM 14 Big Airplane Navi9ation Lights 9V 168 span non flashing2495 RAM 15 Non Flash Nay Lights 9 NEW 94 span w/ wing light conn 1495 RAM 16 Econo Landing Lights 9V servo controlled brightest . 1995 RAM 23 Real Strobe Li9ht 3V brightest.. 2995 RAM 65 T6 Lg Scale Lighting 72-9V Comb #s 04 14 & 16 100 span 5995 6 SEE YOUR DEALER SEND STAMPED ENVELOPE FOR RAM INFO unavailable locally send check money order full credit card info coat tern plus $400 l$50O foreigni immediate shipment Include full address U PS Sorry no cOD m 229B E Rollins Rd d Lake Beach IL 60073 Aza noticed amount wing covered fuselage greater lower-aspect-ratio wings fact area four times much 11 wing 161 wing significant another impurity experiment hard change just thing wings another major difference didnt discuss Aza thickness ratio airfoil determines lot about flies wings same thickness different chords Heres stack up Aspect Ratio 161 41 11 Thickness Ratio 62% 31% 15% know having studied aerodynamics anything given mean line under about 3% thickness ratio flies about same particularly sensitive Reynolds number 6% different matter Know quotes because am sure what have studied applies square-edged small airfoils case certainly using very different airfoils three models highest aspect ratio wing certainly has worst airfoil thickness ratio 161 wing four times thickness ratio 11 wing give wings same airfoil might choose make wings i/s tAs 1/82 wood does make less alike What does same same actual thickness same thickness ratio have read reports about effect changing aspect ratios often left unclear what airfoils used Perhaps models should scaled flying same Reynolds number different sizes wing chords same stabilizers will different sizes stabilizers will flying different June1997 39 KEEP FLYING THAT MODEL FOR YEARS BTA AUTO PILOT real Auto Pilot Designed back-up unit levels skill Inflight ON/OFF Switching Simple Plug Installation Sensors Internal & Unaffected External Conditions Consistent Operation Day Night Overcast Sunny Adjustable Zero & Gains Compatible RC Systems Endorsed Used Top Gun TOC Giant Scale Race Pilots & Experimental Full-Size also II-\--I 1001SEND IOVER 2000 TOOLS & ACCESSORIESFOR YOUR COPY Brand Names. Unusual Items.TODAY Exclusive Products savings up 60% designed make prolect Ieasier enjoyable professional I TO ORDER Send $100 coupon name address ADDRESS_____________________________________________________[v33][b231172014226250]] MlcroMerk 2249 Snyder AveI Berkeley Heights NJ 07922-1595CITYSTATE________ ZIPj B T Automatic Piloting Systems 192 Yorktown Lane a Mesa CA 92626 Phone 714-979-8948 714-979-8947 Send SASE Information Reynolds numbers perhaps affecting performance Again have ask what mean same Once models built weighed simple balance made leftover balsa added clay top center wing until weighed same Perhaps should have put clay centers gravity didnt know point yet now three airplanes sort same subject problems have listed perhaps others havent thought Now add nose weight until flew two ways could just test-fly add subtract clay nose until flew well possible some subjective criterion add remove clay center until weighed same again could balance same relative place say 30% wing chord Again have ask what same trimming Balancing 30% chord point disaster nose-heavy 50% point right either So trimmed trial-and-error reballasted equal weight Now would have ask trimmed optimally difficult part flight testing Ignoring problems have up now getting simple models same going make sure launched same will measure performance going eliminate biasespecially unconscious bias part Aza thought 41 wing would fly best looked normal wasnt sure 161 looked like sailplane worst airfoil undecided what expect also ask what better Ease launch speed straightness flight path Continued page 47 TRU-TURN now offers very finest versatile lightweight PROP HUBS turned solid barstock inside out true running hub new hub will mount motor standard TRU-TURN adapter kit big bird multi-bolt applications TRU-TURN has covered TRU-TURN also has PROP NUT will fit motor precision PROP NUTS come engine thread sizes two different shapes available stock Ask hobby dealer name ZI~ RMadenthe U S PRECISION MODEL PRODUCTS Romco Manufacturing Inc QUALITY VERSA TILITY T LOOKS TY PO Box 836 South Houston Texas 77587 713 943-1867 Z 1997 41 TestinglRaskin Continued page 41 what chose distance measure quality Aza has done lot flying has flown few contests including some hand-launched gliders could see value measure also technically reasonable since related directly glide angle equals lift-to-drag ratio flights start same height least reasonably easy Aza would launch high could reach agreed height wouldnt exactly same wed fly airplane number times troublesome wed get same launch speed Generally harder throw something farther will go isnt strictly true model airplanes hard launch might result loop example launch certainly affects distance Unconscious bias difficult factors deal Unconscious bias experimenter unintentionally makes experiment work way expects otherwise-careful scientists have gotten wrong results because unconscious bias factor what makes necessary blind experimentswhere tester does know factor being tested present medical work double blind experiments often used after results have tallied will experimenters know patient got what treatment what results did test demonstrates unconscious bias very effectively slope soarer operated computer radio often let other people fly threw switch box flying same time told made airplane bit responsive After few minutes asked much improved aileron elevator response flier reported some kind improvement Some said made small difference others said made large difference greatly improved handling found no difference June1997 47 IqI1v-ii New 97 engineers K&B manufacturing come three ingenious improvements have exclusively developed new K&B 61 ABC engine new Iwist head greatly improves engine performance reduces engine wear redesigned porting increases engine power AJso new tuned muffler design actually acts like tuned pipe increasing horsepower making engine run quieter over 50 years K&B Manufactung has leader quality US Mode hobby products continues tradition new K&B 61 ABC Will II PNDesCdptIon 4012-40 MInew/muffier 4075 40 ABC Sped Madne 510067 IliccI Inboard2t 5101 6711 lcd Outboard4011 / Muffler 5350 82 1132ccl Inboard4050- 40R/CA8Cw/Iuned Muffler 5375- 82 Ii 33cclOutboad5299-82 9/C Eluded Fur Heat Sink Headi 8702- 4517Sccl Outboard5250-829/CDucledFur 8907 -21 135cd1 Outboard5605-209/C Sporlufer 8916-21 13Sccllnboard5680-28R/CSpnrlster 9181- 4517ScdInbaard5805-65R/CSportsler 9575-10h164cclOutbaard5905-45R/CSpcinsler ENGIRS DSCR1PI1ON 6050- 61 R/CARC c/Tuned Muffler 6550-619/C w/Muffer 8910- 35cc 1fed Fan 9101- 1Scc[XrcledFun 9505- 1509/C RtHerow/Muffier 9549- 150 9/C Eluded Fan Heal Sink HeadJ 9550- 150R/CDucledFan 520 4533579 / 520453 3583 2100 College Dr. Lake Havasu Cftx ArIzona 86403 r-r,oH k&b@hio1ercor switch connected anything unconscious bias work aspect-ratio tests no way control unconscious bias unless built mechanical launcher still possibility wed unconsciously done better job trimming airplane thought would better measuring flight distance say nearest inch pull tape bit tighter model think will poorly mund up down borderline cases direction expected outcome can honest try cheat happens anyway studies have shown Results tests 11 seemed bestor least consistent achieving distance 41 seemed close second performance 11 single longest flight 161 usually worst Aza conectly concluded test good enough tell anything about effect aspect ratio glide Such conclusion loss Aza learned good experiment can very hard things dont always work clear-cut way youd like did design test eliminate unconscious bias Aza realized models consistenfly performed better others might because aspect ratio other factors slight warp would have build number model sort out accidental essential believe changes beloved designers cannot made isolation can nearly impossible set up experimentally sound testing procedure near-total lack blind testing cannot remember report model airplane experiment controlled unconscious bias Think carefully about claims read about model airplane design See conclusions really tested ask effect mentioned fact effect tesrei Ask yourseif unconscious bias might have present Few claims will pass tests askin 8 Gypsy Hill Rd Pac4fica CA 94044 48 Model Aviation twist-on head precision pin aligns piston sleeve eliminates stripped head bolts provides head torque reduces head leaks increases power increases performance reduces engine wear m increases engine Ilte RIC SERVICE AT ITS BEST AW~NL les Service Anything Radio Controlled Repairs Updates Custom Modifications Frequency Changes 6 Send Legal sized SAE 1997 Meter conversions ACE Airtronics Aristo-craft Cirrus EK Catalog containing lists RIC Futaba Hitec Heathkit Hobby Shack JR Kraft KGL KSE Kline maintenance hints Discover MCard VISA COD KoPropo Pro-Line RCD Tower Hobbies World Engines & others UPS USMAIL FED EX etc Calibrated Equipment Quick Turnaround Walk-in daily service 800 am-S 00 pm Send E-Mail to. PTWaters@junocom KMI 7420 Seven Mile Rd Northville Michigan 48167 Ph 810-486-4800 Fax 810-486-1603
Edition: Model Aviation - 1997/06
Page Numbers: 28, 29, 30, 37, 39, 41, 47, 48
Edition: Model Aviation - 1997/06
Page Numbers: 28, 29, 30, 37, 39, 41, 47, 48
MODEL AIRPLANES Its easy think says author father-andson test program yielded some interesting results 28 Model Aviation f Raskiri explaining term aspect ratio then-nine-year-old son Aza taking part ages-old tradition passing knowledge generation next gave him simple example rectangular wing aspect ratio span divided chord wing foot span foot chord would have aspect ratio . interrupted Right said span four feet . aspect ratio would befour said Aza showed him notate aspect ratios 11 41 talked about bigger wings could carry weightor same weight larger wing could fly slowly smaller wings Aza has flying lot model airplanes made sense him really tiny wing added airplane would have fly very fast stay up Right said pleased observation showed him picture F-104 its tiny wings goes very fast Aza asked question trying lead him think about What difference does aspect ratio make way airplane flies full-size airplanes answered higher aspect ratios make efficient can go farther less fuel example What kind airplanes have very high aspect ratios Aza has plastic models hanging ceiling home including some sailplanes Gliders said can go long ways fuel use thermais climb So dont people just make airplanes large aspect ratios What would look like asked wings would long skinny replied what problems would cause would flex too much especially high speeds would hard put hangars youd need very long ramp get airport would have left subject wanted know did say full-size airplanes Isnt true models too Well extemporized things bit complicated Its easy find out said Aza Lets just make two modelsone high aspect ratio low aspect ratio everything else same see flies better Azas proposal sounded reasonable no finer way get truth Wings quarter-chords aligned Wings centers same line June1997 29 Area4 sq in Span 8 Chord 05 Aspect Ratio 16 Area 4 sq Span 4 Chord 1 Aspect Ratio 4 Area 4 sq Span 2 Chord 2 Aspect Ratio 1 -U 0 well-designed experiment didnt have answer him since make chord wing small becomes less efficient Reynolds number effects works against gains increasing aspect ratio unlike full-scale airplanes Reynolds number effects usually important thought try explain Aza would bit much hed have take lot faith Aza could see test models would have identical could make changed aspect ratio would have keep area constant Aza studied area its relationship multiplication enough mathematics find rectangles same area different aspect ratios decided small simple balsa models wing area four square inches aspect ratio 11 wing would two inches two inches square wing suggested aspect ratio 161 soon drawn rectangle 1/2 inch eight inches long thin wing Another easy span four inches chord inch 41 aspect ratio suggested wing chord 11/2 inches think quite figure span came up number wrong answers before figuring out surprising him correct 10 2/3 inches never built last wing turned out decided wings could conveniently made A2 balsa consistency would just cut pieces square-edged round themjust like F North Pacific Guillow gliders often fly didnt discuss logically no difference between asking about effect aspect ratio effect span experiment could equally well describe wings going build having same areafour square inches spans two four eight inches found hobby shop bought sheet A2 x 2 x 36 balsa wings tail surfaces 1/8 x stick make fuselages little bottle cyanoacrylate CyA glue purchased assemble models stabilizer would 25% area wingour familys standard formula simple gliders made square inch Aza soon sketched out x 2 rectangle chose use twin-fin design since fins would stiffen stabilizer would very easy align fins /2 inch chord 3/4 inch height Aza already knew about using decalage give model pitch stability wanted some way make sure airplanes same amount So just built fuselage shape Three stabilizer/fin assemblies built attached bottom fuselage sticks using square assure straight line ruled across center stabilizer assured centered Things going well until asked should attach wings Aerodynamics texts tell us rectangular flat wing acts though its lift generated line /4 way front airfoil lifting line airfoil one-inch chord behind leading edge way build airplanes put quarter-chord points wings same position fuselage would change weight distribution models keep weight distribution same airfoils would have have centers same position fuselage fun see Aza ponder over concept lifting line something hadnt run before asked could demonstrate him couldnt think easy way demonstrate lifting-line concept Continued page 37 30 Model Aviation wing airfoil 62% 41 wing airfoil 31% 11 wing airfoil 15% End views three wings showing airfoils used scaled equal chord length wing awing b wing c wings b have same total dihedral wings c have same dihedral angle TestinglRaskin Continued page 30 seffled putting centers wings same place Pure experiments give clean answers very hard come aerodynamics business about proper location wings different aspect ratio fine example Airplanes quite sensitive position wing certainly unclear what right way proceed case built models anyway went backyard test fly rise some five feet Aza toss soft grass cushion landings nearly morning windless Dandelion fluffone favorite wind indicatorsdropped straight down two low-aspect-ratio airplanes flew well 161 model bit unstable decided some dihedral would beneficial next question much dihedral Should use same angle dihedral raise wingtips same distance pointed out raising same distance would make angle greater shorter wingssomething immediately clear Aza What does mean two wings different spans aspect ratios have same amount dihedral Again made arbitrary decision keep angle same choice hard justify physically assuming lift generated wing proportional its area like third-graders Aza isnt quite up trigonometry vector representation forces needed explanation trimming however able get 161 fly stably never added dihedral Another difference between models June1997 37 LIGHTING SYSTEMS THE ORIGINALS. Still Best RAM 01Adj Flash Nay Lights 9V NEW 94 spanWI wing light conn$2995 RAM 02Strobe Light 9V adjustable flash rate1995 RAM 03Landing Li9hts 48V receiver controlled3995 RAM 04Mars Rotating Beacon 9V adjustable rate1995 RAM 06 Sky Lights 18 Li9ht Set 72-9V 94 best way fly night 2995 RAM 14 Big Airplane Navi9ation Lights 9V 168 span non flashing2495 RAM 15 Non Flash Nay Lights 9 NEW 94 span w/ wing light conn 1495 RAM 16 Econo Landing Lights 9V servo controlled brightest . 1995 RAM 23 Real Strobe Li9ht 3V brightest.. 2995 RAM 65 T6 Lg Scale Lighting 72-9V Comb #s 04 14 & 16 100 span 5995 6 SEE YOUR DEALER SEND STAMPED ENVELOPE FOR RAM INFO unavailable locally send check money order full credit card info coat tern plus $400 l$50O foreigni immediate shipment Include full address U PS Sorry no cOD m 229B E Rollins Rd d Lake Beach IL 60073 Aza noticed amount wing covered fuselage greater lower-aspect-ratio wings fact area four times much 11 wing 161 wing significant another impurity experiment hard change just thing wings another major difference didnt discuss Aza thickness ratio airfoil determines lot about flies wings same thickness different chords Heres stack up Aspect Ratio 161 41 11 Thickness Ratio 62% 31% 15% know having studied aerodynamics anything given mean line under about 3% thickness ratio flies about same particularly sensitive Reynolds number 6% different matter Know quotes because am sure what have studied applies square-edged small airfoils case certainly using very different airfoils three models highest aspect ratio wing certainly has worst airfoil thickness ratio 161 wing four times thickness ratio 11 wing give wings same airfoil might choose make wings i/s tAs 1/82 wood does make less alike What does same same actual thickness same thickness ratio have read reports about effect changing aspect ratios often left unclear what airfoils used Perhaps models should scaled flying same Reynolds number different sizes wing chords same stabilizers will different sizes stabilizers will flying different June1997 39 KEEP FLYING THAT MODEL FOR YEARS BTA AUTO PILOT real Auto Pilot Designed back-up unit levels skill Inflight ON/OFF Switching Simple Plug Installation Sensors Internal & Unaffected External Conditions Consistent Operation Day Night Overcast Sunny Adjustable Zero & Gains Compatible RC Systems Endorsed Used Top Gun TOC Giant Scale Race Pilots & Experimental Full-Size also II-\--I 1001SEND IOVER 2000 TOOLS & ACCESSORIESFOR YOUR COPY Brand Names. Unusual Items.TODAY Exclusive Products savings up 60% designed make prolect Ieasier enjoyable professional I TO ORDER Send $100 coupon name address ADDRESS_____________________________________________________[v33][b231172014226250]] MlcroMerk 2249 Snyder AveI Berkeley Heights NJ 07922-1595CITYSTATE________ ZIPj B T Automatic Piloting Systems 192 Yorktown Lane a Mesa CA 92626 Phone 714-979-8948 714-979-8947 Send SASE Information Reynolds numbers perhaps affecting performance Again have ask what mean same Once models built weighed simple balance made leftover balsa added clay top center wing until weighed same Perhaps should have put clay centers gravity didnt know point yet now three airplanes sort same subject problems have listed perhaps others havent thought Now add nose weight until flew two ways could just test-fly add subtract clay nose until flew well possible some subjective criterion add remove clay center until weighed same again could balance same relative place say 30% wing chord Again have ask what same trimming Balancing 30% chord point disaster nose-heavy 50% point right either So trimmed trial-and-error reballasted equal weight Now would have ask trimmed optimally difficult part flight testing Ignoring problems have up now getting simple models same going make sure launched same will measure performance going eliminate biasespecially unconscious bias part Aza thought 41 wing would fly best looked normal wasnt sure 161 looked like sailplane worst airfoil undecided what expect also ask what better Ease launch speed straightness flight path Continued page 47 TRU-TURN now offers very finest versatile lightweight PROP HUBS turned solid barstock inside out true running hub new hub will mount motor standard TRU-TURN adapter kit big bird multi-bolt applications TRU-TURN has covered TRU-TURN also has PROP NUT will fit motor precision PROP NUTS come engine thread sizes two different shapes available stock Ask hobby dealer name ZI~ RMadenthe U S PRECISION MODEL PRODUCTS Romco Manufacturing Inc QUALITY VERSA TILITY T LOOKS TY PO Box 836 South Houston Texas 77587 713 943-1867 Z 1997 41 TestinglRaskin Continued page 41 what chose distance measure quality Aza has done lot flying has flown few contests including some hand-launched gliders could see value measure also technically reasonable since related directly glide angle equals lift-to-drag ratio flights start same height least reasonably easy Aza would launch high could reach agreed height wouldnt exactly same wed fly airplane number times troublesome wed get same launch speed Generally harder throw something farther will go isnt strictly true model airplanes hard launch might result loop example launch certainly affects distance Unconscious bias difficult factors deal Unconscious bias experimenter unintentionally makes experiment work way expects otherwise-careful scientists have gotten wrong results because unconscious bias factor what makes necessary blind experimentswhere tester does know factor being tested present medical work double blind experiments often used after results have tallied will experimenters know patient got what treatment what results did test demonstrates unconscious bias very effectively slope soarer operated computer radio often let other people fly threw switch box flying same time told made airplane bit responsive After few minutes asked much improved aileron elevator response flier reported some kind improvement Some said made small difference others said made large difference greatly improved handling found no difference June1997 47 IqI1v-ii New 97 engineers K&B manufacturing come three ingenious improvements have exclusively developed new K&B 61 ABC engine new Iwist head greatly improves engine performance reduces engine wear redesigned porting increases engine power AJso new tuned muffler design actually acts like tuned pipe increasing horsepower making engine run quieter over 50 years K&B Manufactung has leader quality US Mode hobby products continues tradition new K&B 61 ABC Will II PNDesCdptIon 4012-40 MInew/muffier 4075 40 ABC Sped Madne 510067 IliccI Inboard2t 5101 6711 lcd Outboard4011 / Muffler 5350 82 1132ccl Inboard4050- 40R/CA8Cw/Iuned Muffler 5375- 82 Ii 33cclOutboad5299-82 9/C Eluded Fur Heat Sink Headi 8702- 4517Sccl Outboard5250-829/CDucledFur 8907 -21 135cd1 Outboard5605-209/C Sporlufer 8916-21 13Sccllnboard5680-28R/CSpnrlster 9181- 4517ScdInbaard5805-65R/CSportsler 9575-10h164cclOutbaard5905-45R/CSpcinsler ENGIRS DSCR1PI1ON 6050- 61 R/CARC c/Tuned Muffler 6550-619/C w/Muffer 8910- 35cc 1fed Fan 9101- 1Scc[XrcledFun 9505- 1509/C RtHerow/Muffier 9549- 150 9/C Eluded Fan Heal Sink HeadJ 9550- 150R/CDucledFan 520 4533579 / 520453 3583 2100 College Dr. Lake Havasu Cftx ArIzona 86403 r-r,oH k&b@hio1ercor switch connected anything unconscious bias work aspect-ratio tests no way control unconscious bias unless built mechanical launcher still possibility wed unconsciously done better job trimming airplane thought would better measuring flight distance say nearest inch pull tape bit tighter model think will poorly mund up down borderline cases direction expected outcome can honest try cheat happens anyway studies have shown Results tests 11 seemed bestor least consistent achieving distance 41 seemed close second performance 11 single longest flight 161 usually worst Aza conectly concluded test good enough tell anything about effect aspect ratio glide Such conclusion loss Aza learned good experiment can very hard things dont always work clear-cut way youd like did design test eliminate unconscious bias Aza realized models consistenfly performed better others might because aspect ratio other factors slight warp would have build number model sort out accidental essential believe changes beloved designers cannot made isolation can nearly impossible set up experimentally sound testing procedure near-total lack blind testing cannot remember report model airplane experiment controlled unconscious bias Think carefully about claims read about model airplane design See conclusions really tested ask effect mentioned fact effect tesrei Ask yourseif unconscious bias might have present Few claims will pass tests askin 8 Gypsy Hill Rd Pac4fica CA 94044 48 Model Aviation twist-on head precision pin aligns piston sleeve eliminates stripped head bolts provides head torque reduces head leaks increases power increases performance reduces engine wear m increases engine Ilte RIC SERVICE AT ITS BEST AW~NL les Service Anything Radio Controlled Repairs Updates Custom Modifications Frequency Changes 6 Send Legal sized SAE 1997 Meter conversions ACE Airtronics Aristo-craft Cirrus EK Catalog containing lists RIC Futaba Hitec Heathkit Hobby Shack JR Kraft KGL KSE Kline maintenance hints Discover MCard VISA COD KoPropo Pro-Line RCD Tower Hobbies World Engines & others UPS USMAIL FED EX etc Calibrated Equipment Quick Turnaround Walk-in daily service 800 am-S 00 pm Send E-Mail to. PTWaters@junocom KMI 7420 Seven Mile Rd Northville Michigan 48167 Ph 810-486-4800 Fax 810-486-1603
Edition: Model Aviation - 1997/06
Page Numbers: 28, 29, 30, 37, 39, 41, 47, 48
MODEL AIRPLANES Its easy think says author father-andson test program yielded some interesting results 28 Model Aviation f Raskiri explaining term aspect ratio then-nine-year-old son Aza taking part ages-old tradition passing knowledge generation next gave him simple example rectangular wing aspect ratio span divided chord wing foot span foot chord would have aspect ratio . interrupted Right said span four feet . aspect ratio would befour said Aza showed him notate aspect ratios 11 41 talked about bigger wings could carry weightor same weight larger wing could fly slowly smaller wings Aza has flying lot model airplanes made sense him really tiny wing added airplane would have fly very fast stay up Right said pleased observation showed him picture F-104 its tiny wings goes very fast Aza asked question trying lead him think about What difference does aspect ratio make way airplane flies full-size airplanes answered higher aspect ratios make efficient can go farther less fuel example What kind airplanes have very high aspect ratios Aza has plastic models hanging ceiling home including some sailplanes Gliders said can go long ways fuel use thermais climb So dont people just make airplanes large aspect ratios What would look like asked wings would long skinny replied what problems would cause would flex too much especially high speeds would hard put hangars youd need very long ramp get airport would have left subject wanted know did say full-size airplanes Isnt true models too Well extemporized things bit complicated Its easy find out said Aza Lets just make two modelsone high aspect ratio low aspect ratio everything else same see flies better Azas proposal sounded reasonable no finer way get truth Wings quarter-chords aligned Wings centers same line June1997 29 Area4 sq in Span 8 Chord 05 Aspect Ratio 16 Area 4 sq Span 4 Chord 1 Aspect Ratio 4 Area 4 sq Span 2 Chord 2 Aspect Ratio 1 -U 0 well-designed experiment didnt have answer him since make chord wing small becomes less efficient Reynolds number effects works against gains increasing aspect ratio unlike full-scale airplanes Reynolds number effects usually important thought try explain Aza would bit much hed have take lot faith Aza could see test models would have identical could make changed aspect ratio would have keep area constant Aza studied area its relationship multiplication enough mathematics find rectangles same area different aspect ratios decided small simple balsa models wing area four square inches aspect ratio 11 wing would two inches two inches square wing suggested aspect ratio 161 soon drawn rectangle 1/2 inch eight inches long thin wing Another easy span four inches chord inch 41 aspect ratio suggested wing chord 11/2 inches think quite figure span came up number wrong answers before figuring out surprising him correct 10 2/3 inches never built last wing turned out decided wings could conveniently made A2 balsa consistency would just cut pieces square-edged round themjust like F North Pacific Guillow gliders often fly didnt discuss logically no difference between asking about effect aspect ratio effect span experiment could equally well describe wings going build having same areafour square inches spans two four eight inches found hobby shop bought sheet A2 x 2 x 36 balsa wings tail surfaces 1/8 x stick make fuselages little bottle cyanoacrylate CyA glue purchased assemble models stabilizer would 25% area wingour familys standard formula simple gliders made square inch Aza soon sketched out x 2 rectangle chose use twin-fin design since fins would stiffen stabilizer would very easy align fins /2 inch chord 3/4 inch height Aza already knew about using decalage give model pitch stability wanted some way make sure airplanes same amount So just built fuselage shape Three stabilizer/fin assemblies built attached bottom fuselage sticks using square assure straight line ruled across center stabilizer assured centered Things going well until asked should attach wings Aerodynamics texts tell us rectangular flat wing acts though its lift generated line /4 way front airfoil lifting line airfoil one-inch chord behind leading edge way build airplanes put quarter-chord points wings same position fuselage would change weight distribution models keep weight distribution same airfoils would have have centers same position fuselage fun see Aza ponder over concept lifting line something hadnt run before asked could demonstrate him couldnt think easy way demonstrate lifting-line concept Continued page 37 30 Model Aviation wing airfoil 62% 41 wing airfoil 31% 11 wing airfoil 15% End views three wings showing airfoils used scaled equal chord length wing awing b wing c wings b have same total dihedral wings c have same dihedral angle TestinglRaskin Continued page 30 seffled putting centers wings same place Pure experiments give clean answers very hard come aerodynamics business about proper location wings different aspect ratio fine example Airplanes quite sensitive position wing certainly unclear what right way proceed case built models anyway went backyard test fly rise some five feet Aza toss soft grass cushion landings nearly morning windless Dandelion fluffone favorite wind indicatorsdropped straight down two low-aspect-ratio airplanes flew well 161 model bit unstable decided some dihedral would beneficial next question much dihedral Should use same angle dihedral raise wingtips same distance pointed out raising same distance would make angle greater shorter wingssomething immediately clear Aza What does mean two wings different spans aspect ratios have same amount dihedral Again made arbitrary decision keep angle same choice hard justify physically assuming lift generated wing proportional its area like third-graders Aza isnt quite up trigonometry vector representation forces needed explanation trimming however able get 161 fly stably never added dihedral Another difference between models June1997 37 LIGHTING SYSTEMS THE ORIGINALS. Still Best RAM 01Adj Flash Nay Lights 9V NEW 94 spanWI wing light conn$2995 RAM 02Strobe Light 9V adjustable flash rate1995 RAM 03Landing Li9hts 48V receiver controlled3995 RAM 04Mars Rotating Beacon 9V adjustable rate1995 RAM 06 Sky Lights 18 Li9ht Set 72-9V 94 best way fly night 2995 RAM 14 Big Airplane Navi9ation Lights 9V 168 span non flashing2495 RAM 15 Non Flash Nay Lights 9 NEW 94 span w/ wing light conn 1495 RAM 16 Econo Landing Lights 9V servo controlled brightest . 1995 RAM 23 Real Strobe Li9ht 3V brightest.. 2995 RAM 65 T6 Lg Scale Lighting 72-9V Comb #s 04 14 & 16 100 span 5995 6 SEE YOUR DEALER SEND STAMPED ENVELOPE FOR RAM INFO unavailable locally send check money order full credit card info coat tern plus $400 l$50O foreigni immediate shipment Include full address U PS Sorry no cOD m 229B E Rollins Rd d Lake Beach IL 60073 Aza noticed amount wing covered fuselage greater lower-aspect-ratio wings fact area four times much 11 wing 161 wing significant another impurity experiment hard change just thing wings another major difference didnt discuss Aza thickness ratio airfoil determines lot about flies wings same thickness different chords Heres stack up Aspect Ratio 161 41 11 Thickness Ratio 62% 31% 15% know having studied aerodynamics anything given mean line under about 3% thickness ratio flies about same particularly sensitive Reynolds number 6% different matter Know quotes because am sure what have studied applies square-edged small airfoils case certainly using very different airfoils three models highest aspect ratio wing certainly has worst airfoil thickness ratio 161 wing four times thickness ratio 11 wing give wings same airfoil might choose make wings i/s tAs 1/82 wood does make less alike What does same same actual thickness same thickness ratio have read reports about effect changing aspect ratios often left unclear what airfoils used Perhaps models should scaled flying same Reynolds number different sizes wing chords same stabilizers will different sizes stabilizers will flying different June1997 39 KEEP FLYING THAT MODEL FOR YEARS BTA AUTO PILOT real Auto Pilot Designed back-up unit levels skill Inflight ON/OFF Switching Simple Plug Installation Sensors Internal & Unaffected External Conditions Consistent Operation Day Night Overcast Sunny Adjustable Zero & Gains Compatible RC Systems Endorsed Used Top Gun TOC Giant Scale Race Pilots & Experimental Full-Size also II-\--I 1001SEND IOVER 2000 TOOLS & ACCESSORIESFOR YOUR COPY Brand Names. Unusual Items.TODAY Exclusive Products savings up 60% designed make prolect Ieasier enjoyable professional I TO ORDER Send $100 coupon name address ADDRESS_____________________________________________________[v33][b231172014226250]] MlcroMerk 2249 Snyder AveI Berkeley Heights NJ 07922-1595CITYSTATE________ ZIPj B T Automatic Piloting Systems 192 Yorktown Lane a Mesa CA 92626 Phone 714-979-8948 714-979-8947 Send SASE Information Reynolds numbers perhaps affecting performance Again have ask what mean same Once models built weighed simple balance made leftover balsa added clay top center wing until weighed same Perhaps should have put clay centers gravity didnt know point yet now three airplanes sort same subject problems have listed perhaps others havent thought Now add nose weight until flew two ways could just test-fly add subtract clay nose until flew well possible some subjective criterion add remove clay center until weighed same again could balance same relative place say 30% wing chord Again have ask what same trimming Balancing 30% chord point disaster nose-heavy 50% point right either So trimmed trial-and-error reballasted equal weight Now would have ask trimmed optimally difficult part flight testing Ignoring problems have up now getting simple models same going make sure launched same will measure performance going eliminate biasespecially unconscious bias part Aza thought 41 wing would fly best looked normal wasnt sure 161 looked like sailplane worst airfoil undecided what expect also ask what better Ease launch speed straightness flight path Continued page 47 TRU-TURN now offers very finest versatile lightweight PROP HUBS turned solid barstock inside out true running hub new hub will mount motor standard TRU-TURN adapter kit big bird multi-bolt applications TRU-TURN has covered TRU-TURN also has PROP NUT will fit motor precision PROP NUTS come engine thread sizes two different shapes available stock Ask hobby dealer name ZI~ RMadenthe U S PRECISION MODEL PRODUCTS Romco Manufacturing Inc QUALITY VERSA TILITY T LOOKS TY PO Box 836 South Houston Texas 77587 713 943-1867 Z 1997 41 TestinglRaskin Continued page 41 what chose distance measure quality Aza has done lot flying has flown few contests including some hand-launched gliders could see value measure also technically reasonable since related directly glide angle equals lift-to-drag ratio flights start same height least reasonably easy Aza would launch high could reach agreed height wouldnt exactly same wed fly airplane number times troublesome wed get same launch speed Generally harder throw something farther will go isnt strictly true model airplanes hard launch might result loop example launch certainly affects distance Unconscious bias difficult factors deal Unconscious bias experimenter unintentionally makes experiment work way expects otherwise-careful scientists have gotten wrong results because unconscious bias factor what makes necessary blind experimentswhere tester does know factor being tested present medical work double blind experiments often used after results have tallied will experimenters know patient got what treatment what results did test demonstrates unconscious bias very effectively slope soarer operated computer radio often let other people fly threw switch box flying same time told made airplane bit responsive After few minutes asked much improved aileron elevator response flier reported some kind improvement Some said made small difference others said made large difference greatly improved handling found no difference June1997 47 IqI1v-ii New 97 engineers K&B manufacturing come three ingenious improvements have exclusively developed new K&B 61 ABC engine new Iwist head greatly improves engine performance reduces engine wear redesigned porting increases engine power AJso new tuned muffler design actually acts like tuned pipe increasing horsepower making engine run quieter over 50 years K&B Manufactung has leader quality US Mode hobby products continues tradition new K&B 61 ABC Will II PNDesCdptIon 4012-40 MInew/muffier 4075 40 ABC Sped Madne 510067 IliccI Inboard2t 5101 6711 lcd Outboard4011 / Muffler 5350 82 1132ccl Inboard4050- 40R/CA8Cw/Iuned Muffler 5375- 82 Ii 33cclOutboad5299-82 9/C Eluded Fur Heat Sink Headi 8702- 4517Sccl Outboard5250-829/CDucledFur 8907 -21 135cd1 Outboard5605-209/C Sporlufer 8916-21 13Sccllnboard5680-28R/CSpnrlster 9181- 4517ScdInbaard5805-65R/CSportsler 9575-10h164cclOutbaard5905-45R/CSpcinsler ENGIRS DSCR1PI1ON 6050- 61 R/CARC c/Tuned Muffler 6550-619/C w/Muffer 8910- 35cc 1fed Fan 9101- 1Scc[XrcledFun 9505- 1509/C RtHerow/Muffier 9549- 150 9/C Eluded Fan Heal Sink HeadJ 9550- 150R/CDucledFan 520 4533579 / 520453 3583 2100 College Dr. Lake Havasu Cftx ArIzona 86403 r-r,oH k&b@hio1ercor switch connected anything unconscious bias work aspect-ratio tests no way control unconscious bias unless built mechanical launcher still possibility wed unconsciously done better job trimming airplane thought would better measuring flight distance say nearest inch pull tape bit tighter model think will poorly mund up down borderline cases direction expected outcome can honest try cheat happens anyway studies have shown Results tests 11 seemed bestor least consistent achieving distance 41 seemed close second performance 11 single longest flight 161 usually worst Aza conectly concluded test good enough tell anything about effect aspect ratio glide Such conclusion loss Aza learned good experiment can very hard things dont always work clear-cut way youd like did design test eliminate unconscious bias Aza realized models consistenfly performed better others might because aspect ratio other factors slight warp would have build number model sort out accidental essential believe changes beloved designers cannot made isolation can nearly impossible set up experimentally sound testing procedure near-total lack blind testing cannot remember report model airplane experiment controlled unconscious bias Think carefully about claims read about model airplane design See conclusions really tested ask effect mentioned fact effect tesrei Ask yourseif unconscious bias might have present Few claims will pass tests askin 8 Gypsy Hill Rd Pac4fica CA 94044 48 Model Aviation twist-on head precision pin aligns piston sleeve eliminates stripped head bolts provides head torque reduces head leaks increases power increases performance reduces engine wear m increases engine Ilte RIC SERVICE AT ITS BEST AW~NL les Service Anything Radio Controlled Repairs Updates Custom Modifications Frequency Changes 6 Send Legal sized SAE 1997 Meter conversions ACE Airtronics Aristo-craft Cirrus EK Catalog containing lists RIC Futaba Hitec Heathkit Hobby Shack JR Kraft KGL KSE Kline maintenance hints Discover MCard VISA COD KoPropo Pro-Line RCD Tower Hobbies World Engines & others UPS USMAIL FED EX etc Calibrated Equipment Quick Turnaround Walk-in daily service 800 am-S 00 pm Send E-Mail to. PTWaters@junocom KMI 7420 Seven Mile Rd Northville Michigan 48167 Ph 810-486-4800 Fax 810-486-1603
Edition: Model Aviation - 1997/06
Page Numbers: 28, 29, 30, 37, 39, 41, 47, 48
MODEL AIRPLANES Its easy think says author father-andson test program yielded some interesting results 28 Model Aviation f Raskiri explaining term aspect ratio then-nine-year-old son Aza taking part ages-old tradition passing knowledge generation next gave him simple example rectangular wing aspect ratio span divided chord wing foot span foot chord would have aspect ratio . interrupted Right said span four feet . aspect ratio would befour said Aza showed him notate aspect ratios 11 41 talked about bigger wings could carry weightor same weight larger wing could fly slowly smaller wings Aza has flying lot model airplanes made sense him really tiny wing added airplane would have fly very fast stay up Right said pleased observation showed him picture F-104 its tiny wings goes very fast Aza asked question trying lead him think about What difference does aspect ratio make way airplane flies full-size airplanes answered higher aspect ratios make efficient can go farther less fuel example What kind airplanes have very high aspect ratios Aza has plastic models hanging ceiling home including some sailplanes Gliders said can go long ways fuel use thermais climb So dont people just make airplanes large aspect ratios What would look like asked wings would long skinny replied what problems would cause would flex too much especially high speeds would hard put hangars youd need very long ramp get airport would have left subject wanted know did say full-size airplanes Isnt true models too Well extemporized things bit complicated Its easy find out said Aza Lets just make two modelsone high aspect ratio low aspect ratio everything else same see flies better Azas proposal sounded reasonable no finer way get truth Wings quarter-chords aligned Wings centers same line June1997 29 Area4 sq in Span 8 Chord 05 Aspect Ratio 16 Area 4 sq Span 4 Chord 1 Aspect Ratio 4 Area 4 sq Span 2 Chord 2 Aspect Ratio 1 -U 0 well-designed experiment didnt have answer him since make chord wing small becomes less efficient Reynolds number effects works against gains increasing aspect ratio unlike full-scale airplanes Reynolds number effects usually important thought try explain Aza would bit much hed have take lot faith Aza could see test models would have identical could make changed aspect ratio would have keep area constant Aza studied area its relationship multiplication enough mathematics find rectangles same area different aspect ratios decided small simple balsa models wing area four square inches aspect ratio 11 wing would two inches two inches square wing suggested aspect ratio 161 soon drawn rectangle 1/2 inch eight inches long thin wing Another easy span four inches chord inch 41 aspect ratio suggested wing chord 11/2 inches think quite figure span came up number wrong answers before figuring out surprising him correct 10 2/3 inches never built last wing turned out decided wings could conveniently made A2 balsa consistency would just cut pieces square-edged round themjust like F North Pacific Guillow gliders often fly didnt discuss logically no difference between asking about effect aspect ratio effect span experiment could equally well describe wings going build having same areafour square inches spans two four eight inches found hobby shop bought sheet A2 x 2 x 36 balsa wings tail surfaces 1/8 x stick make fuselages little bottle cyanoacrylate CyA glue purchased assemble models stabilizer would 25% area wingour familys standard formula simple gliders made square inch Aza soon sketched out x 2 rectangle chose use twin-fin design since fins would stiffen stabilizer would very easy align fins /2 inch chord 3/4 inch height Aza already knew about using decalage give model pitch stability wanted some way make sure airplanes same amount So just built fuselage shape Three stabilizer/fin assemblies built attached bottom fuselage sticks using square assure straight line ruled across center stabilizer assured centered Things going well until asked should attach wings Aerodynamics texts tell us rectangular flat wing acts though its lift generated line /4 way front airfoil lifting line airfoil one-inch chord behind leading edge way build airplanes put quarter-chord points wings same position fuselage would change weight distribution models keep weight distribution same airfoils would have have centers same position fuselage fun see Aza ponder over concept lifting line something hadnt run before asked could demonstrate him couldnt think easy way demonstrate lifting-line concept Continued page 37 30 Model Aviation wing airfoil 62% 41 wing airfoil 31% 11 wing airfoil 15% End views three wings showing airfoils used scaled equal chord length wing awing b wing c wings b have same total dihedral wings c have same dihedral angle TestinglRaskin Continued page 30 seffled putting centers wings same place Pure experiments give clean answers very hard come aerodynamics business about proper location wings different aspect ratio fine example Airplanes quite sensitive position wing certainly unclear what right way proceed case built models anyway went backyard test fly rise some five feet Aza toss soft grass cushion landings nearly morning windless Dandelion fluffone favorite wind indicatorsdropped straight down two low-aspect-ratio airplanes flew well 161 model bit unstable decided some dihedral would beneficial next question much dihedral Should use same angle dihedral raise wingtips same distance pointed out raising same distance would make angle greater shorter wingssomething immediately clear Aza What does mean two wings different spans aspect ratios have same amount dihedral Again made arbitrary decision keep angle same choice hard justify physically assuming lift generated wing proportional its area like third-graders Aza isnt quite up trigonometry vector representation forces needed explanation trimming however able get 161 fly stably never added dihedral Another difference between models June1997 37 LIGHTING SYSTEMS THE ORIGINALS. Still Best RAM 01Adj Flash Nay Lights 9V NEW 94 spanWI wing light conn$2995 RAM 02Strobe Light 9V adjustable flash rate1995 RAM 03Landing Li9hts 48V receiver controlled3995 RAM 04Mars Rotating Beacon 9V adjustable rate1995 RAM 06 Sky Lights 18 Li9ht Set 72-9V 94 best way fly night 2995 RAM 14 Big Airplane Navi9ation Lights 9V 168 span non flashing2495 RAM 15 Non Flash Nay Lights 9 NEW 94 span w/ wing light conn 1495 RAM 16 Econo Landing Lights 9V servo controlled brightest . 1995 RAM 23 Real Strobe Li9ht 3V brightest.. 2995 RAM 65 T6 Lg Scale Lighting 72-9V Comb #s 04 14 & 16 100 span 5995 6 SEE YOUR DEALER SEND STAMPED ENVELOPE FOR RAM INFO unavailable locally send check money order full credit card info coat tern plus $400 l$50O foreigni immediate shipment Include full address U PS Sorry no cOD m 229B E Rollins Rd d Lake Beach IL 60073 Aza noticed amount wing covered fuselage greater lower-aspect-ratio wings fact area four times much 11 wing 161 wing significant another impurity experiment hard change just thing wings another major difference didnt discuss Aza thickness ratio airfoil determines lot about flies wings same thickness different chords Heres stack up Aspect Ratio 161 41 11 Thickness Ratio 62% 31% 15% know having studied aerodynamics anything given mean line under about 3% thickness ratio flies about same particularly sensitive Reynolds number 6% different matter Know quotes because am sure what have studied applies square-edged small airfoils case certainly using very different airfoils three models highest aspect ratio wing certainly has worst airfoil thickness ratio 161 wing four times thickness ratio 11 wing give wings same airfoil might choose make wings i/s tAs 1/82 wood does make less alike What does same same actual thickness same thickness ratio have read reports about effect changing aspect ratios often left unclear what airfoils used Perhaps models should scaled flying same Reynolds number different sizes wing chords same stabilizers will different sizes stabilizers will flying different June1997 39 KEEP FLYING THAT MODEL FOR YEARS BTA AUTO PILOT real Auto Pilot Designed back-up unit levels skill Inflight ON/OFF Switching Simple Plug Installation Sensors Internal & Unaffected External Conditions Consistent Operation Day Night Overcast Sunny Adjustable Zero & Gains Compatible RC Systems Endorsed Used Top Gun TOC Giant Scale Race Pilots & Experimental Full-Size also II-\--I 1001SEND IOVER 2000 TOOLS & ACCESSORIESFOR YOUR COPY Brand Names. Unusual Items.TODAY Exclusive Products savings up 60% designed make prolect Ieasier enjoyable professional I TO ORDER Send $100 coupon name address ADDRESS_____________________________________________________[v33][b231172014226250]] MlcroMerk 2249 Snyder AveI Berkeley Heights NJ 07922-1595CITYSTATE________ ZIPj B T Automatic Piloting Systems 192 Yorktown Lane a Mesa CA 92626 Phone 714-979-8948 714-979-8947 Send SASE Information Reynolds numbers perhaps affecting performance Again have ask what mean same Once models built weighed simple balance made leftover balsa added clay top center wing until weighed same Perhaps should have put clay centers gravity didnt know point yet now three airplanes sort same subject problems have listed perhaps others havent thought Now add nose weight until flew two ways could just test-fly add subtract clay nose until flew well possible some subjective criterion add remove clay center until weighed same again could balance same relative place say 30% wing chord Again have ask what same trimming Balancing 30% chord point disaster nose-heavy 50% point right either So trimmed trial-and-error reballasted equal weight Now would have ask trimmed optimally difficult part flight testing Ignoring problems have up now getting simple models same going make sure launched same will measure performance going eliminate biasespecially unconscious bias part Aza thought 41 wing would fly best looked normal wasnt sure 161 looked like sailplane worst airfoil undecided what expect also ask what better Ease launch speed straightness flight path Continued page 47 TRU-TURN now offers very finest versatile lightweight PROP HUBS turned solid barstock inside out true running hub new hub will mount motor standard TRU-TURN adapter kit big bird multi-bolt applications TRU-TURN has covered TRU-TURN also has PROP NUT will fit motor precision PROP NUTS come engine thread sizes two different shapes available stock Ask hobby dealer name ZI~ RMadenthe U S PRECISION MODEL PRODUCTS Romco Manufacturing Inc QUALITY VERSA TILITY T LOOKS TY PO Box 836 South Houston Texas 77587 713 943-1867 Z 1997 41 TestinglRaskin Continued page 41 what chose distance measure quality Aza has done lot flying has flown few contests including some hand-launched gliders could see value measure also technically reasonable since related directly glide angle equals lift-to-drag ratio flights start same height least reasonably easy Aza would launch high could reach agreed height wouldnt exactly same wed fly airplane number times troublesome wed get same launch speed Generally harder throw something farther will go isnt strictly true model airplanes hard launch might result loop example launch certainly affects distance Unconscious bias difficult factors deal Unconscious bias experimenter unintentionally makes experiment work way expects otherwise-careful scientists have gotten wrong results because unconscious bias factor what makes necessary blind experimentswhere tester does know factor being tested present medical work double blind experiments often used after results have tallied will experimenters know patient got what treatment what results did test demonstrates unconscious bias very effectively slope soarer operated computer radio often let other people fly threw switch box flying same time told made airplane bit responsive After few minutes asked much improved aileron elevator response flier reported some kind improvement Some said made small difference others said made large difference greatly improved handling found no difference June1997 47 IqI1v-ii New 97 engineers K&B manufacturing come three ingenious improvements have exclusively developed new K&B 61 ABC engine new Iwist head greatly improves engine performance reduces engine wear redesigned porting increases engine power AJso new tuned muffler design actually acts like tuned pipe increasing horsepower making engine run quieter over 50 years K&B Manufactung has leader quality US Mode hobby products continues tradition new K&B 61 ABC Will II PNDesCdptIon 4012-40 MInew/muffier 4075 40 ABC Sped Madne 510067 IliccI Inboard2t 5101 6711 lcd Outboard4011 / Muffler 5350 82 1132ccl Inboard4050- 40R/CA8Cw/Iuned Muffler 5375- 82 Ii 33cclOutboad5299-82 9/C Eluded Fur Heat Sink Headi 8702- 4517Sccl Outboard5250-829/CDucledFur 8907 -21 135cd1 Outboard5605-209/C Sporlufer 8916-21 13Sccllnboard5680-28R/CSpnrlster 9181- 4517ScdInbaard5805-65R/CSportsler 9575-10h164cclOutbaard5905-45R/CSpcinsler ENGIRS DSCR1PI1ON 6050- 61 R/CARC c/Tuned Muffler 6550-619/C w/Muffer 8910- 35cc 1fed Fan 9101- 1Scc[XrcledFun 9505- 1509/C RtHerow/Muffier 9549- 150 9/C Eluded Fan Heal Sink HeadJ 9550- 150R/CDucledFan 520 4533579 / 520453 3583 2100 College Dr. Lake Havasu Cftx ArIzona 86403 r-r,oH k&b@hio1ercor switch connected anything unconscious bias work aspect-ratio tests no way control unconscious bias unless built mechanical launcher still possibility wed unconsciously done better job trimming airplane thought would better measuring flight distance say nearest inch pull tape bit tighter model think will poorly mund up down borderline cases direction expected outcome can honest try cheat happens anyway studies have shown Results tests 11 seemed bestor least consistent achieving distance 41 seemed close second performance 11 single longest flight 161 usually worst Aza conectly concluded test good enough tell anything about effect aspect ratio glide Such conclusion loss Aza learned good experiment can very hard things dont always work clear-cut way youd like did design test eliminate unconscious bias Aza realized models consistenfly performed better others might because aspect ratio other factors slight warp would have build number model sort out accidental essential believe changes beloved designers cannot made isolation can nearly impossible set up experimentally sound testing procedure near-total lack blind testing cannot remember report model airplane experiment controlled unconscious bias Think carefully about claims read about model airplane design See conclusions really tested ask effect mentioned fact effect tesrei Ask yourseif unconscious bias might have present Few claims will pass tests askin 8 Gypsy Hill Rd Pac4fica CA 94044 48 Model Aviation twist-on head precision pin aligns piston sleeve eliminates stripped head bolts provides head torque reduces head leaks increases power increases performance reduces engine wear m increases engine Ilte RIC SERVICE AT ITS BEST AW~NL les Service Anything Radio Controlled Repairs Updates Custom Modifications Frequency Changes 6 Send Legal sized SAE 1997 Meter conversions ACE Airtronics Aristo-craft Cirrus EK Catalog containing lists RIC Futaba Hitec Heathkit Hobby Shack JR Kraft KGL KSE Kline maintenance hints Discover MCard VISA COD KoPropo Pro-Line RCD Tower Hobbies World Engines & others UPS USMAIL FED EX etc Calibrated Equipment Quick Turnaround Walk-in daily service 800 am-S 00 pm Send E-Mail to. PTWaters@junocom KMI 7420 Seven Mile Rd Northville Michigan 48167 Ph 810-486-4800 Fax 810-486-1603
Edition: Model Aviation - 1997/06
Page Numbers: 28, 29, 30, 37, 39, 41, 47, 48
MODEL AIRPLANES Its easy think says author father-andson test program yielded some interesting results 28 Model Aviation f Raskiri explaining term aspect ratio then-nine-year-old son Aza taking part ages-old tradition passing knowledge generation next gave him simple example rectangular wing aspect ratio span divided chord wing foot span foot chord would have aspect ratio . interrupted Right said span four feet . aspect ratio would befour said Aza showed him notate aspect ratios 11 41 talked about bigger wings could carry weightor same weight larger wing could fly slowly smaller wings Aza has flying lot model airplanes made sense him really tiny wing added airplane would have fly very fast stay up Right said pleased observation showed him picture F-104 its tiny wings goes very fast Aza asked question trying lead him think about What difference does aspect ratio make way airplane flies full-size airplanes answered higher aspect ratios make efficient can go farther less fuel example What kind airplanes have very high aspect ratios Aza has plastic models hanging ceiling home including some sailplanes Gliders said can go long ways fuel use thermais climb So dont people just make airplanes large aspect ratios What would look like asked wings would long skinny replied what problems would cause would flex too much especially high speeds would hard put hangars youd need very long ramp get airport would have left subject wanted know did say full-size airplanes Isnt true models too Well extemporized things bit complicated Its easy find out said Aza Lets just make two modelsone high aspect ratio low aspect ratio everything else same see flies better Azas proposal sounded reasonable no finer way get truth Wings quarter-chords aligned Wings centers same line June1997 29 Area4 sq in Span 8 Chord 05 Aspect Ratio 16 Area 4 sq Span 4 Chord 1 Aspect Ratio 4 Area 4 sq Span 2 Chord 2 Aspect Ratio 1 -U 0 well-designed experiment didnt have answer him since make chord wing small becomes less efficient Reynolds number effects works against gains increasing aspect ratio unlike full-scale airplanes Reynolds number effects usually important thought try explain Aza would bit much hed have take lot faith Aza could see test models would have identical could make changed aspect ratio would have keep area constant Aza studied area its relationship multiplication enough mathematics find rectangles same area different aspect ratios decided small simple balsa models wing area four square inches aspect ratio 11 wing would two inches two inches square wing suggested aspect ratio 161 soon drawn rectangle 1/2 inch eight inches long thin wing Another easy span four inches chord inch 41 aspect ratio suggested wing chord 11/2 inches think quite figure span came up number wrong answers before figuring out surprising him correct 10 2/3 inches never built last wing turned out decided wings could conveniently made A2 balsa consistency would just cut pieces square-edged round themjust like F North Pacific Guillow gliders often fly didnt discuss logically no difference between asking about effect aspect ratio effect span experiment could equally well describe wings going build having same areafour square inches spans two four eight inches found hobby shop bought sheet A2 x 2 x 36 balsa wings tail surfaces 1/8 x stick make fuselages little bottle cyanoacrylate CyA glue purchased assemble models stabilizer would 25% area wingour familys standard formula simple gliders made square inch Aza soon sketched out x 2 rectangle chose use twin-fin design since fins would stiffen stabilizer would very easy align fins /2 inch chord 3/4 inch height Aza already knew about using decalage give model pitch stability wanted some way make sure airplanes same amount So just built fuselage shape Three stabilizer/fin assemblies built attached bottom fuselage sticks using square assure straight line ruled across center stabilizer assured centered Things going well until asked should attach wings Aerodynamics texts tell us rectangular flat wing acts though its lift generated line /4 way front airfoil lifting line airfoil one-inch chord behind leading edge way build airplanes put quarter-chord points wings same position fuselage would change weight distribution models keep weight distribution same airfoils would have have centers same position fuselage fun see Aza ponder over concept lifting line something hadnt run before asked could demonstrate him couldnt think easy way demonstrate lifting-line concept Continued page 37 30 Model Aviation wing airfoil 62% 41 wing airfoil 31% 11 wing airfoil 15% End views three wings showing airfoils used scaled equal chord length wing awing b wing c wings b have same total dihedral wings c have same dihedral angle TestinglRaskin Continued page 30 seffled putting centers wings same place Pure experiments give clean answers very hard come aerodynamics business about proper location wings different aspect ratio fine example Airplanes quite sensitive position wing certainly unclear what right way proceed case built models anyway went backyard test fly rise some five feet Aza toss soft grass cushion landings nearly morning windless Dandelion fluffone favorite wind indicatorsdropped straight down two low-aspect-ratio airplanes flew well 161 model bit unstable decided some dihedral would beneficial next question much dihedral Should use same angle dihedral raise wingtips same distance pointed out raising same distance would make angle greater shorter wingssomething immediately clear Aza What does mean two wings different spans aspect ratios have same amount dihedral Again made arbitrary decision keep angle same choice hard justify physically assuming lift generated wing proportional its area like third-graders Aza isnt quite up trigonometry vector representation forces needed explanation trimming however able get 161 fly stably never added dihedral Another difference between models June1997 37 LIGHTING SYSTEMS THE ORIGINALS. Still Best RAM 01Adj Flash Nay Lights 9V NEW 94 spanWI wing light conn$2995 RAM 02Strobe Light 9V adjustable flash rate1995 RAM 03Landing Li9hts 48V receiver controlled3995 RAM 04Mars Rotating Beacon 9V adjustable rate1995 RAM 06 Sky Lights 18 Li9ht Set 72-9V 94 best way fly night 2995 RAM 14 Big Airplane Navi9ation Lights 9V 168 span non flashing2495 RAM 15 Non Flash Nay Lights 9 NEW 94 span w/ wing light conn 1495 RAM 16 Econo Landing Lights 9V servo controlled brightest . 1995 RAM 23 Real Strobe Li9ht 3V brightest.. 2995 RAM 65 T6 Lg Scale Lighting 72-9V Comb #s 04 14 & 16 100 span 5995 6 SEE YOUR DEALER SEND STAMPED ENVELOPE FOR RAM INFO unavailable locally send check money order full credit card info coat tern plus $400 l$50O foreigni immediate shipment Include full address U PS Sorry no cOD m 229B E Rollins Rd d Lake Beach IL 60073 Aza noticed amount wing covered fuselage greater lower-aspect-ratio wings fact area four times much 11 wing 161 wing significant another impurity experiment hard change just thing wings another major difference didnt discuss Aza thickness ratio airfoil determines lot about flies wings same thickness different chords Heres stack up Aspect Ratio 161 41 11 Thickness Ratio 62% 31% 15% know having studied aerodynamics anything given mean line under about 3% thickness ratio flies about same particularly sensitive Reynolds number 6% different matter Know quotes because am sure what have studied applies square-edged small airfoils case certainly using very different airfoils three models highest aspect ratio wing certainly has worst airfoil thickness ratio 161 wing four times thickness ratio 11 wing give wings same airfoil might choose make wings i/s tAs 1/82 wood does make less alike What does same same actual thickness same thickness ratio have read reports about effect changing aspect ratios often left unclear what airfoils used Perhaps models should scaled flying same Reynolds number different sizes wing chords same stabilizers will different sizes stabilizers will flying different June1997 39 KEEP FLYING THAT MODEL FOR YEARS BTA AUTO PILOT real Auto Pilot Designed back-up unit levels skill Inflight ON/OFF Switching Simple Plug Installation Sensors Internal & Unaffected External Conditions Consistent Operation Day Night Overcast Sunny Adjustable Zero & Gains Compatible RC Systems Endorsed Used Top Gun TOC Giant Scale Race Pilots & Experimental Full-Size also II-\--I 1001SEND IOVER 2000 TOOLS & ACCESSORIESFOR YOUR COPY Brand Names. Unusual Items.TODAY Exclusive Products savings up 60% designed make prolect Ieasier enjoyable professional I TO ORDER Send $100 coupon name address ADDRESS_____________________________________________________[v33][b231172014226250]] MlcroMerk 2249 Snyder AveI Berkeley Heights NJ 07922-1595CITYSTATE________ ZIPj B T Automatic Piloting Systems 192 Yorktown Lane a Mesa CA 92626 Phone 714-979-8948 714-979-8947 Send SASE Information Reynolds numbers perhaps affecting performance Again have ask what mean same Once models built weighed simple balance made leftover balsa added clay top center wing until weighed same Perhaps should have put clay centers gravity didnt know point yet now three airplanes sort same subject problems have listed perhaps others havent thought Now add nose weight until flew two ways could just test-fly add subtract clay nose until flew well possible some subjective criterion add remove clay center until weighed same again could balance same relative place say 30% wing chord Again have ask what same trimming Balancing 30% chord point disaster nose-heavy 50% point right either So trimmed trial-and-error reballasted equal weight Now would have ask trimmed optimally difficult part flight testing Ignoring problems have up now getting simple models same going make sure launched same will measure performance going eliminate biasespecially unconscious bias part Aza thought 41 wing would fly best looked normal wasnt sure 161 looked like sailplane worst airfoil undecided what expect also ask what better Ease launch speed straightness flight path Continued page 47 TRU-TURN now offers very finest versatile lightweight PROP HUBS turned solid barstock inside out true running hub new hub will mount motor standard TRU-TURN adapter kit big bird multi-bolt applications TRU-TURN has covered TRU-TURN also has PROP NUT will fit motor precision PROP NUTS come engine thread sizes two different shapes available stock Ask hobby dealer name ZI~ RMadenthe U S PRECISION MODEL PRODUCTS Romco Manufacturing Inc QUALITY VERSA TILITY T LOOKS TY PO Box 836 South Houston Texas 77587 713 943-1867 Z 1997 41 TestinglRaskin Continued page 41 what chose distance measure quality Aza has done lot flying has flown few contests including some hand-launched gliders could see value measure also technically reasonable since related directly glide angle equals lift-to-drag ratio flights start same height least reasonably easy Aza would launch high could reach agreed height wouldnt exactly same wed fly airplane number times troublesome wed get same launch speed Generally harder throw something farther will go isnt strictly true model airplanes hard launch might result loop example launch certainly affects distance Unconscious bias difficult factors deal Unconscious bias experimenter unintentionally makes experiment work way expects otherwise-careful scientists have gotten wrong results because unconscious bias factor what makes necessary blind experimentswhere tester does know factor being tested present medical work double blind experiments often used after results have tallied will experimenters know patient got what treatment what results did test demonstrates unconscious bias very effectively slope soarer operated computer radio often let other people fly threw switch box flying same time told made airplane bit responsive After few minutes asked much improved aileron elevator response flier reported some kind improvement Some said made small difference others said made large difference greatly improved handling found no difference June1997 47 IqI1v-ii New 97 engineers K&B manufacturing come three ingenious improvements have exclusively developed new K&B 61 ABC engine new Iwist head greatly improves engine performance reduces engine wear redesigned porting increases engine power AJso new tuned muffler design actually acts like tuned pipe increasing horsepower making engine run quieter over 50 years K&B Manufactung has leader quality US Mode hobby products continues tradition new K&B 61 ABC Will II PNDesCdptIon 4012-40 MInew/muffier 4075 40 ABC Sped Madne 510067 IliccI Inboard2t 5101 6711 lcd Outboard4011 / Muffler 5350 82 1132ccl Inboard4050- 40R/CA8Cw/Iuned Muffler 5375- 82 Ii 33cclOutboad5299-82 9/C Eluded Fur Heat Sink Headi 8702- 4517Sccl Outboard5250-829/CDucledFur 8907 -21 135cd1 Outboard5605-209/C Sporlufer 8916-21 13Sccllnboard5680-28R/CSpnrlster 9181- 4517ScdInbaard5805-65R/CSportsler 9575-10h164cclOutbaard5905-45R/CSpcinsler ENGIRS DSCR1PI1ON 6050- 61 R/CARC c/Tuned Muffler 6550-619/C w/Muffer 8910- 35cc 1fed Fan 9101- 1Scc[XrcledFun 9505- 1509/C RtHerow/Muffier 9549- 150 9/C Eluded Fan Heal Sink HeadJ 9550- 150R/CDucledFan 520 4533579 / 520453 3583 2100 College Dr. Lake Havasu Cftx ArIzona 86403 r-r,oH k&b@hio1ercor switch connected anything unconscious bias work aspect-ratio tests no way control unconscious bias unless built mechanical launcher still possibility wed unconsciously done better job trimming airplane thought would better measuring flight distance say nearest inch pull tape bit tighter model think will poorly mund up down borderline cases direction expected outcome can honest try cheat happens anyway studies have shown Results tests 11 seemed bestor least consistent achieving distance 41 seemed close second performance 11 single longest flight 161 usually worst Aza conectly concluded test good enough tell anything about effect aspect ratio glide Such conclusion loss Aza learned good experiment can very hard things dont always work clear-cut way youd like did design test eliminate unconscious bias Aza realized models consistenfly performed better others might because aspect ratio other factors slight warp would have build number model sort out accidental essential believe changes beloved designers cannot made isolation can nearly impossible set up experimentally sound testing procedure near-total lack blind testing cannot remember report model airplane experiment controlled unconscious bias Think carefully about claims read about model airplane design See conclusions really tested ask effect mentioned fact effect tesrei Ask yourseif unconscious bias might have present Few claims will pass tests askin 8 Gypsy Hill Rd Pac4fica CA 94044 48 Model Aviation twist-on head precision pin aligns piston sleeve eliminates stripped head bolts provides head torque reduces head leaks increases power increases performance reduces engine wear m increases engine Ilte RIC SERVICE AT ITS BEST AW~NL les Service Anything Radio Controlled Repairs Updates Custom Modifications Frequency Changes 6 Send Legal sized SAE 1997 Meter conversions ACE Airtronics Aristo-craft Cirrus EK Catalog containing lists RIC Futaba Hitec Heathkit Hobby Shack JR Kraft KGL KSE Kline maintenance hints Discover MCard VISA COD KoPropo Pro-Line RCD Tower Hobbies World Engines & others UPS USMAIL FED EX etc Calibrated Equipment Quick Turnaround Walk-in daily service 800 am-S 00 pm Send E-Mail to. PTWaters@junocom KMI 7420 Seven Mile Rd Northville Michigan 48167 Ph 810-486-4800 Fax 810-486-1603
Edition: Model Aviation - 1997/06
Page Numbers: 28, 29, 30, 37, 39, 41, 47, 48
MODEL AIRPLANES Its easy think says author father-andson test program yielded some interesting results 28 Model Aviation f Raskiri explaining term aspect ratio then-nine-year-old son Aza taking part ages-old tradition passing knowledge generation next gave him simple example rectangular wing aspect ratio span divided chord wing foot span foot chord would have aspect ratio . interrupted Right said span four feet . aspect ratio would befour said Aza showed him notate aspect ratios 11 41 talked about bigger wings could carry weightor same weight larger wing could fly slowly smaller wings Aza has flying lot model airplanes made sense him really tiny wing added airplane would have fly very fast stay up Right said pleased observation showed him picture F-104 its tiny wings goes very fast Aza asked question trying lead him think about What difference does aspect ratio make way airplane flies full-size airplanes answered higher aspect ratios make efficient can go farther less fuel example What kind airplanes have very high aspect ratios Aza has plastic models hanging ceiling home including some sailplanes Gliders said can go long ways fuel use thermais climb So dont people just make airplanes large aspect ratios What would look like asked wings would long skinny replied what problems would cause would flex too much especially high speeds would hard put hangars youd need very long ramp get airport would have left subject wanted know did say full-size airplanes Isnt true models too Well extemporized things bit complicated Its easy find out said Aza Lets just make two modelsone high aspect ratio low aspect ratio everything else same see flies better Azas proposal sounded reasonable no finer way get truth Wings quarter-chords aligned Wings centers same line June1997 29 Area4 sq in Span 8 Chord 05 Aspect Ratio 16 Area 4 sq Span 4 Chord 1 Aspect Ratio 4 Area 4 sq Span 2 Chord 2 Aspect Ratio 1 -U 0 well-designed experiment didnt have answer him since make chord wing small becomes less efficient Reynolds number effects works against gains increasing aspect ratio unlike full-scale airplanes Reynolds number effects usually important thought try explain Aza would bit much hed have take lot faith Aza could see test models would have identical could make changed aspect ratio would have keep area constant Aza studied area its relationship multiplication enough mathematics find rectangles same area different aspect ratios decided small simple balsa models wing area four square inches aspect ratio 11 wing would two inches two inches square wing suggested aspect ratio 161 soon drawn rectangle 1/2 inch eight inches long thin wing Another easy span four inches chord inch 41 aspect ratio suggested wing chord 11/2 inches think quite figure span came up number wrong answers before figuring out surprising him correct 10 2/3 inches never built last wing turned out decided wings could conveniently made A2 balsa consistency would just cut pieces square-edged round themjust like F North Pacific Guillow gliders often fly didnt discuss logically no difference between asking about effect aspect ratio effect span experiment could equally well describe wings going build having same areafour square inches spans two four eight inches found hobby shop bought sheet A2 x 2 x 36 balsa wings tail surfaces 1/8 x stick make fuselages little bottle cyanoacrylate CyA glue purchased assemble models stabilizer would 25% area wingour familys standard formula simple gliders made square inch Aza soon sketched out x 2 rectangle chose use twin-fin design since fins would stiffen stabilizer would very easy align fins /2 inch chord 3/4 inch height Aza already knew about using decalage give model pitch stability wanted some way make sure airplanes same amount So just built fuselage shape Three stabilizer/fin assemblies built attached bottom fuselage sticks using square assure straight line ruled across center stabilizer assured centered Things going well until asked should attach wings Aerodynamics texts tell us rectangular flat wing acts though its lift generated line /4 way front airfoil lifting line airfoil one-inch chord behind leading edge way build airplanes put quarter-chord points wings same position fuselage would change weight distribution models keep weight distribution same airfoils would have have centers same position fuselage fun see Aza ponder over concept lifting line something hadnt run before asked could demonstrate him couldnt think easy way demonstrate lifting-line concept Continued page 37 30 Model Aviation wing airfoil 62% 41 wing airfoil 31% 11 wing airfoil 15% End views three wings showing airfoils used scaled equal chord length wing awing b wing c wings b have same total dihedral wings c have same dihedral angle TestinglRaskin Continued page 30 seffled putting centers wings same place Pure experiments give clean answers very hard come aerodynamics business about proper location wings different aspect ratio fine example Airplanes quite sensitive position wing certainly unclear what right way proceed case built models anyway went backyard test fly rise some five feet Aza toss soft grass cushion landings nearly morning windless Dandelion fluffone favorite wind indicatorsdropped straight down two low-aspect-ratio airplanes flew well 161 model bit unstable decided some dihedral would beneficial next question much dihedral Should use same angle dihedral raise wingtips same distance pointed out raising same distance would make angle greater shorter wingssomething immediately clear Aza What does mean two wings different spans aspect ratios have same amount dihedral Again made arbitrary decision keep angle same choice hard justify physically assuming lift generated wing proportional its area like third-graders Aza isnt quite up trigonometry vector representation forces needed explanation trimming however able get 161 fly stably never added dihedral Another difference between models June1997 37 LIGHTING SYSTEMS THE ORIGINALS. Still Best RAM 01Adj Flash Nay Lights 9V NEW 94 spanWI wing light conn$2995 RAM 02Strobe Light 9V adjustable flash rate1995 RAM 03Landing Li9hts 48V receiver controlled3995 RAM 04Mars Rotating Beacon 9V adjustable rate1995 RAM 06 Sky Lights 18 Li9ht Set 72-9V 94 best way fly night 2995 RAM 14 Big Airplane Navi9ation Lights 9V 168 span non flashing2495 RAM 15 Non Flash Nay Lights 9 NEW 94 span w/ wing light conn 1495 RAM 16 Econo Landing Lights 9V servo controlled brightest . 1995 RAM 23 Real Strobe Li9ht 3V brightest.. 2995 RAM 65 T6 Lg Scale Lighting 72-9V Comb #s 04 14 & 16 100 span 5995 6 SEE YOUR DEALER SEND STAMPED ENVELOPE FOR RAM INFO unavailable locally send check money order full credit card info coat tern plus $400 l$50O foreigni immediate shipment Include full address U PS Sorry no cOD m 229B E Rollins Rd d Lake Beach IL 60073 Aza noticed amount wing covered fuselage greater lower-aspect-ratio wings fact area four times much 11 wing 161 wing significant another impurity experiment hard change just thing wings another major difference didnt discuss Aza thickness ratio airfoil determines lot about flies wings same thickness different chords Heres stack up Aspect Ratio 161 41 11 Thickness Ratio 62% 31% 15% know having studied aerodynamics anything given mean line under about 3% thickness ratio flies about same particularly sensitive Reynolds number 6% different matter Know quotes because am sure what have studied applies square-edged small airfoils case certainly using very different airfoils three models highest aspect ratio wing certainly has worst airfoil thickness ratio 161 wing four times thickness ratio 11 wing give wings same airfoil might choose make wings i/s tAs 1/82 wood does make less alike What does same same actual thickness same thickness ratio have read reports about effect changing aspect ratios often left unclear what airfoils used Perhaps models should scaled flying same Reynolds number different sizes wing chords same stabilizers will different sizes stabilizers will flying different June1997 39 KEEP FLYING THAT MODEL FOR YEARS BTA AUTO PILOT real Auto Pilot Designed back-up unit levels skill Inflight ON/OFF Switching Simple Plug Installation Sensors Internal & Unaffected External Conditions Consistent Operation Day Night Overcast Sunny Adjustable Zero & Gains Compatible RC Systems Endorsed Used Top Gun TOC Giant Scale Race Pilots & Experimental Full-Size also II-\--I 1001SEND IOVER 2000 TOOLS & ACCESSORIESFOR YOUR COPY Brand Names. Unusual Items.TODAY Exclusive Products savings up 60% designed make prolect Ieasier enjoyable professional I TO ORDER Send $100 coupon name address ADDRESS_____________________________________________________[v33][b231172014226250]] MlcroMerk 2249 Snyder AveI Berkeley Heights NJ 07922-1595CITYSTATE________ ZIPj B T Automatic Piloting Systems 192 Yorktown Lane a Mesa CA 92626 Phone 714-979-8948 714-979-8947 Send SASE Information Reynolds numbers perhaps affecting performance Again have ask what mean same Once models built weighed simple balance made leftover balsa added clay top center wing until weighed same Perhaps should have put clay centers gravity didnt know point yet now three airplanes sort same subject problems have listed perhaps others havent thought Now add nose weight until flew two ways could just test-fly add subtract clay nose until flew well possible some subjective criterion add remove clay center until weighed same again could balance same relative place say 30% wing chord Again have ask what same trimming Balancing 30% chord point disaster nose-heavy 50% point right either So trimmed trial-and-error reballasted equal weight Now would have ask trimmed optimally difficult part flight testing Ignoring problems have up now getting simple models same going make sure launched same will measure performance going eliminate biasespecially unconscious bias part Aza thought 41 wing would fly best looked normal wasnt sure 161 looked like sailplane worst airfoil undecided what expect also ask what better Ease launch speed straightness flight path Continued page 47 TRU-TURN now offers very finest versatile lightweight PROP HUBS turned solid barstock inside out true running hub new hub will mount motor standard TRU-TURN adapter kit big bird multi-bolt applications TRU-TURN has covered TRU-TURN also has PROP NUT will fit motor precision PROP NUTS come engine thread sizes two different shapes available stock Ask hobby dealer name ZI~ RMadenthe U S PRECISION MODEL PRODUCTS Romco Manufacturing Inc QUALITY VERSA TILITY T LOOKS TY PO Box 836 South Houston Texas 77587 713 943-1867 Z 1997 41 TestinglRaskin Continued page 41 what chose distance measure quality Aza has done lot flying has flown few contests including some hand-launched gliders could see value measure also technically reasonable since related directly glide angle equals lift-to-drag ratio flights start same height least reasonably easy Aza would launch high could reach agreed height wouldnt exactly same wed fly airplane number times troublesome wed get same launch speed Generally harder throw something farther will go isnt strictly true model airplanes hard launch might result loop example launch certainly affects distance Unconscious bias difficult factors deal Unconscious bias experimenter unintentionally makes experiment work way expects otherwise-careful scientists have gotten wrong results because unconscious bias factor what makes necessary blind experimentswhere tester does know factor being tested present medical work double blind experiments often used after results have tallied will experimenters know patient got what treatment what results did test demonstrates unconscious bias very effectively slope soarer operated computer radio often let other people fly threw switch box flying same time told made airplane bit responsive After few minutes asked much improved aileron elevator response flier reported some kind improvement Some said made small difference others said made large difference greatly improved handling found no difference June1997 47 IqI1v-ii New 97 engineers K&B manufacturing come three ingenious improvements have exclusively developed new K&B 61 ABC engine new Iwist head greatly improves engine performance reduces engine wear redesigned porting increases engine power AJso new tuned muffler design actually acts like tuned pipe increasing horsepower making engine run quieter over 50 years K&B Manufactung has leader quality US Mode hobby products continues tradition new K&B 61 ABC Will II PNDesCdptIon 4012-40 MInew/muffier 4075 40 ABC Sped Madne 510067 IliccI Inboard2t 5101 6711 lcd Outboard4011 / Muffler 5350 82 1132ccl Inboard4050- 40R/CA8Cw/Iuned Muffler 5375- 82 Ii 33cclOutboad5299-82 9/C Eluded Fur Heat Sink Headi 8702- 4517Sccl Outboard5250-829/CDucledFur 8907 -21 135cd1 Outboard5605-209/C Sporlufer 8916-21 13Sccllnboard5680-28R/CSpnrlster 9181- 4517ScdInbaard5805-65R/CSportsler 9575-10h164cclOutbaard5905-45R/CSpcinsler ENGIRS DSCR1PI1ON 6050- 61 R/CARC c/Tuned Muffler 6550-619/C w/Muffer 8910- 35cc 1fed Fan 9101- 1Scc[XrcledFun 9505- 1509/C RtHerow/Muffier 9549- 150 9/C Eluded Fan Heal Sink HeadJ 9550- 150R/CDucledFan 520 4533579 / 520453 3583 2100 College Dr. Lake Havasu Cftx ArIzona 86403 r-r,oH k&b@hio1ercor switch connected anything unconscious bias work aspect-ratio tests no way control unconscious bias unless built mechanical launcher still possibility wed unconsciously done better job trimming airplane thought would better measuring flight distance say nearest inch pull tape bit tighter model think will poorly mund up down borderline cases direction expected outcome can honest try cheat happens anyway studies have shown Results tests 11 seemed bestor least consistent achieving distance 41 seemed close second performance 11 single longest flight 161 usually worst Aza conectly concluded test good enough tell anything about effect aspect ratio glide Such conclusion loss Aza learned good experiment can very hard things dont always work clear-cut way youd like did design test eliminate unconscious bias Aza realized models consistenfly performed better others might because aspect ratio other factors slight warp would have build number model sort out accidental essential believe changes beloved designers cannot made isolation can nearly impossible set up experimentally sound testing procedure near-total lack blind testing cannot remember report model airplane experiment controlled unconscious bias Think carefully about claims read about model airplane design See conclusions really tested ask effect mentioned fact effect tesrei Ask yourseif unconscious bias might have present Few claims will pass tests askin 8 Gypsy Hill Rd Pac4fica CA 94044 48 Model Aviation twist-on head precision pin aligns piston sleeve eliminates stripped head bolts provides head torque reduces head leaks increases power increases performance reduces engine wear m increases engine Ilte RIC SERVICE AT ITS BEST AW~NL les Service Anything Radio Controlled Repairs Updates Custom Modifications Frequency Changes 6 Send Legal sized SAE 1997 Meter conversions ACE Airtronics Aristo-craft Cirrus EK Catalog containing lists RIC Futaba Hitec Heathkit Hobby Shack JR Kraft KGL KSE Kline maintenance hints Discover MCard VISA COD KoPropo Pro-Line RCD Tower Hobbies World Engines & others UPS USMAIL FED EX etc Calibrated Equipment Quick Turnaround Walk-in daily service 800 am-S 00 pm Send E-Mail to. PTWaters@junocom KMI 7420 Seven Mile Rd Northville Michigan 48167 Ph 810-486-4800 Fax 810-486-1603
Edition: Model Aviation - 1997/06
Page Numbers: 28, 29, 30, 37, 39, 41, 47, 48
MODEL AIRPLANES Its easy think says author father-andson test program yielded some interesting results 28 Model Aviation f Raskiri explaining term aspect ratio then-nine-year-old son Aza taking part ages-old tradition passing knowledge generation next gave him simple example rectangular wing aspect ratio span divided chord wing foot span foot chord would have aspect ratio . interrupted Right said span four feet . aspect ratio would befour said Aza showed him notate aspect ratios 11 41 talked about bigger wings could carry weightor same weight larger wing could fly slowly smaller wings Aza has flying lot model airplanes made sense him really tiny wing added airplane would have fly very fast stay up Right said pleased observation showed him picture F-104 its tiny wings goes very fast Aza asked question trying lead him think about What difference does aspect ratio make way airplane flies full-size airplanes answered higher aspect ratios make efficient can go farther less fuel example What kind airplanes have very high aspect ratios Aza has plastic models hanging ceiling home including some sailplanes Gliders said can go long ways fuel use thermais climb So dont people just make airplanes large aspect ratios What would look like asked wings would long skinny replied what problems would cause would flex too much especially high speeds would hard put hangars youd need very long ramp get airport would have left subject wanted know did say full-size airplanes Isnt true models too Well extemporized things bit complicated Its easy find out said Aza Lets just make two modelsone high aspect ratio low aspect ratio everything else same see flies better Azas proposal sounded reasonable no finer way get truth Wings quarter-chords aligned Wings centers same line June1997 29 Area4 sq in Span 8 Chord 05 Aspect Ratio 16 Area 4 sq Span 4 Chord 1 Aspect Ratio 4 Area 4 sq Span 2 Chord 2 Aspect Ratio 1 -U 0 well-designed experiment didnt have answer him since make chord wing small becomes less efficient Reynolds number effects works against gains increasing aspect ratio unlike full-scale airplanes Reynolds number effects usually important thought try explain Aza would bit much hed have take lot faith Aza could see test models would have identical could make changed aspect ratio would have keep area constant Aza studied area its relationship multiplication enough mathematics find rectangles same area different aspect ratios decided small simple balsa models wing area four square inches aspect ratio 11 wing would two inches two inches square wing suggested aspect ratio 161 soon drawn rectangle 1/2 inch eight inches long thin wing Another easy span four inches chord inch 41 aspect ratio suggested wing chord 11/2 inches think quite figure span came up number wrong answers before figuring out surprising him correct 10 2/3 inches never built last wing turned out decided wings could conveniently made A2 balsa consistency would just cut pieces square-edged round themjust like F North Pacific Guillow gliders often fly didnt discuss logically no difference between asking about effect aspect ratio effect span experiment could equally well describe wings going build having same areafour square inches spans two four eight inches found hobby shop bought sheet A2 x 2 x 36 balsa wings tail surfaces 1/8 x stick make fuselages little bottle cyanoacrylate CyA glue purchased assemble models stabilizer would 25% area wingour familys standard formula simple gliders made square inch Aza soon sketched out x 2 rectangle chose use twin-fin design since fins would stiffen stabilizer would very easy align fins /2 inch chord 3/4 inch height Aza already knew about using decalage give model pitch stability wanted some way make sure airplanes same amount So just built fuselage shape Three stabilizer/fin assemblies built attached bottom fuselage sticks using square assure straight line ruled across center stabilizer assured centered Things going well until asked should attach wings Aerodynamics texts tell us rectangular flat wing acts though its lift generated line /4 way front airfoil lifting line airfoil one-inch chord behind leading edge way build airplanes put quarter-chord points wings same position fuselage would change weight distribution models keep weight distribution same airfoils would have have centers same position fuselage fun see Aza ponder over concept lifting line something hadnt run before asked could demonstrate him couldnt think easy way demonstrate lifting-line concept Continued page 37 30 Model Aviation wing airfoil 62% 41 wing airfoil 31% 11 wing airfoil 15% End views three wings showing airfoils used scaled equal chord length wing awing b wing c wings b have same total dihedral wings c have same dihedral angle TestinglRaskin Continued page 30 seffled putting centers wings same place Pure experiments give clean answers very hard come aerodynamics business about proper location wings different aspect ratio fine example Airplanes quite sensitive position wing certainly unclear what right way proceed case built models anyway went backyard test fly rise some five feet Aza toss soft grass cushion landings nearly morning windless Dandelion fluffone favorite wind indicatorsdropped straight down two low-aspect-ratio airplanes flew well 161 model bit unstable decided some dihedral would beneficial next question much dihedral Should use same angle dihedral raise wingtips same distance pointed out raising same distance would make angle greater shorter wingssomething immediately clear Aza What does mean two wings different spans aspect ratios have same amount dihedral Again made arbitrary decision keep angle same choice hard justify physically assuming lift generated wing proportional its area like third-graders Aza isnt quite up trigonometry vector representation forces needed explanation trimming however able get 161 fly stably never added dihedral Another difference between models June1997 37 LIGHTING SYSTEMS THE ORIGINALS. Still Best RAM 01Adj Flash Nay Lights 9V NEW 94 spanWI wing light conn$2995 RAM 02Strobe Light 9V adjustable flash rate1995 RAM 03Landing Li9hts 48V receiver controlled3995 RAM 04Mars Rotating Beacon 9V adjustable rate1995 RAM 06 Sky Lights 18 Li9ht Set 72-9V 94 best way fly night 2995 RAM 14 Big Airplane Navi9ation Lights 9V 168 span non flashing2495 RAM 15 Non Flash Nay Lights 9 NEW 94 span w/ wing light conn 1495 RAM 16 Econo Landing Lights 9V servo controlled brightest . 1995 RAM 23 Real Strobe Li9ht 3V brightest.. 2995 RAM 65 T6 Lg Scale Lighting 72-9V Comb #s 04 14 & 16 100 span 5995 6 SEE YOUR DEALER SEND STAMPED ENVELOPE FOR RAM INFO unavailable locally send check money order full credit card info coat tern plus $400 l$50O foreigni immediate shipment Include full address U PS Sorry no cOD m 229B E Rollins Rd d Lake Beach IL 60073 Aza noticed amount wing covered fuselage greater lower-aspect-ratio wings fact area four times much 11 wing 161 wing significant another impurity experiment hard change just thing wings another major difference didnt discuss Aza thickness ratio airfoil determines lot about flies wings same thickness different chords Heres stack up Aspect Ratio 161 41 11 Thickness Ratio 62% 31% 15% know having studied aerodynamics anything given mean line under about 3% thickness ratio flies about same particularly sensitive Reynolds number 6% different matter Know quotes because am sure what have studied applies square-edged small airfoils case certainly using very different airfoils three models highest aspect ratio wing certainly has worst airfoil thickness ratio 161 wing four times thickness ratio 11 wing give wings same airfoil might choose make wings i/s tAs 1/82 wood does make less alike What does same same actual thickness same thickness ratio have read reports about effect changing aspect ratios often left unclear what airfoils used Perhaps models should scaled flying same Reynolds number different sizes wing chords same stabilizers will different sizes stabilizers will flying different June1997 39 KEEP FLYING THAT MODEL FOR YEARS BTA AUTO PILOT real Auto Pilot Designed back-up unit levels skill Inflight ON/OFF Switching Simple Plug Installation Sensors Internal & Unaffected External Conditions Consistent Operation Day Night Overcast Sunny Adjustable Zero & Gains Compatible RC Systems Endorsed Used Top Gun TOC Giant Scale Race Pilots & Experimental Full-Size also II-\--I 1001SEND IOVER 2000 TOOLS & ACCESSORIESFOR YOUR COPY Brand Names. Unusual Items.TODAY Exclusive Products savings up 60% designed make prolect Ieasier enjoyable professional I TO ORDER Send $100 coupon name address ADDRESS_____________________________________________________[v33][b231172014226250]] MlcroMerk 2249 Snyder AveI Berkeley Heights NJ 07922-1595CITYSTATE________ ZIPj B T Automatic Piloting Systems 192 Yorktown Lane a Mesa CA 92626 Phone 714-979-8948 714-979-8947 Send SASE Information Reynolds numbers perhaps affecting performance Again have ask what mean same Once models built weighed simple balance made leftover balsa added clay top center wing until weighed same Perhaps should have put clay centers gravity didnt know point yet now three airplanes sort same subject problems have listed perhaps others havent thought Now add nose weight until flew two ways could just test-fly add subtract clay nose until flew well possible some subjective criterion add remove clay center until weighed same again could balance same relative place say 30% wing chord Again have ask what same trimming Balancing 30% chord point disaster nose-heavy 50% point right either So trimmed trial-and-error reballasted equal weight Now would have ask trimmed optimally difficult part flight testing Ignoring problems have up now getting simple models same going make sure launched same will measure performance going eliminate biasespecially unconscious bias part Aza thought 41 wing would fly best looked normal wasnt sure 161 looked like sailplane worst airfoil undecided what expect also ask what better Ease launch speed straightness flight path Continued page 47 TRU-TURN now offers very finest versatile lightweight PROP HUBS turned solid barstock inside out true running hub new hub will mount motor standard TRU-TURN adapter kit big bird multi-bolt applications TRU-TURN has covered TRU-TURN also has PROP NUT will fit motor precision PROP NUTS come engine thread sizes two different shapes available stock Ask hobby dealer name ZI~ RMadenthe U S PRECISION MODEL PRODUCTS Romco Manufacturing Inc QUALITY VERSA TILITY T LOOKS TY PO Box 836 South Houston Texas 77587 713 943-1867 Z 1997 41 TestinglRaskin Continued page 41 what chose distance measure quality Aza has done lot flying has flown few contests including some hand-launched gliders could see value measure also technically reasonable since related directly glide angle equals lift-to-drag ratio flights start same height least reasonably easy Aza would launch high could reach agreed height wouldnt exactly same wed fly airplane number times troublesome wed get same launch speed Generally harder throw something farther will go isnt strictly true model airplanes hard launch might result loop example launch certainly affects distance Unconscious bias difficult factors deal Unconscious bias experimenter unintentionally makes experiment work way expects otherwise-careful scientists have gotten wrong results because unconscious bias factor what makes necessary blind experimentswhere tester does know factor being tested present medical work double blind experiments often used after results have tallied will experimenters know patient got what treatment what results did test demonstrates unconscious bias very effectively slope soarer operated computer radio often let other people fly threw switch box flying same time told made airplane bit responsive After few minutes asked much improved aileron elevator response flier reported some kind improvement Some said made small difference others said made large difference greatly improved handling found no difference June1997 47 IqI1v-ii New 97 engineers K&B manufacturing come three ingenious improvements have exclusively developed new K&B 61 ABC engine new Iwist head greatly improves engine performance reduces engine wear redesigned porting increases engine power AJso new tuned muffler design actually acts like tuned pipe increasing horsepower making engine run quieter over 50 years K&B Manufactung has leader quality US Mode hobby products continues tradition new K&B 61 ABC Will II PNDesCdptIon 4012-40 MInew/muffier 4075 40 ABC Sped Madne 510067 IliccI Inboard2t 5101 6711 lcd Outboard4011 / Muffler 5350 82 1132ccl Inboard4050- 40R/CA8Cw/Iuned Muffler 5375- 82 Ii 33cclOutboad5299-82 9/C Eluded Fur Heat Sink Headi 8702- 4517Sccl Outboard5250-829/CDucledFur 8907 -21 135cd1 Outboard5605-209/C Sporlufer 8916-21 13Sccllnboard5680-28R/CSpnrlster 9181- 4517ScdInbaard5805-65R/CSportsler 9575-10h164cclOutbaard5905-45R/CSpcinsler ENGIRS DSCR1PI1ON 6050- 61 R/CARC c/Tuned Muffler 6550-619/C w/Muffer 8910- 35cc 1fed Fan 9101- 1Scc[XrcledFun 9505- 1509/C RtHerow/Muffier 9549- 150 9/C Eluded Fan Heal Sink HeadJ 9550- 150R/CDucledFan 520 4533579 / 520453 3583 2100 College Dr. Lake Havasu Cftx ArIzona 86403 r-r,oH k&b@hio1ercor switch connected anything unconscious bias work aspect-ratio tests no way control unconscious bias unless built mechanical launcher still possibility wed unconsciously done better job trimming airplane thought would better measuring flight distance say nearest inch pull tape bit tighter model think will poorly mund up down borderline cases direction expected outcome can honest try cheat happens anyway studies have shown Results tests 11 seemed bestor least consistent achieving distance 41 seemed close second performance 11 single longest flight 161 usually worst Aza conectly concluded test good enough tell anything about effect aspect ratio glide Such conclusion loss Aza learned good experiment can very hard things dont always work clear-cut way youd like did design test eliminate unconscious bias Aza realized models consistenfly performed better others might because aspect ratio other factors slight warp would have build number model sort out accidental essential believe changes beloved designers cannot made isolation can nearly impossible set up experimentally sound testing procedure near-total lack blind testing cannot remember report model airplane experiment controlled unconscious bias Think carefully about claims read about model airplane design See conclusions really tested ask effect mentioned fact effect tesrei Ask yourseif unconscious bias might have present Few claims will pass tests askin 8 Gypsy Hill Rd Pac4fica CA 94044 48 Model Aviation twist-on head precision pin aligns piston sleeve eliminates stripped head bolts provides head torque reduces head leaks increases power increases performance reduces engine wear m increases engine Ilte RIC SERVICE AT ITS BEST AW~NL les Service Anything Radio Controlled Repairs Updates Custom Modifications Frequency Changes 6 Send Legal sized SAE 1997 Meter conversions ACE Airtronics Aristo-craft Cirrus EK Catalog containing lists RIC Futaba Hitec Heathkit Hobby Shack JR Kraft KGL KSE Kline maintenance hints Discover MCard VISA COD KoPropo Pro-Line RCD Tower Hobbies World Engines & others UPS USMAIL FED EX etc Calibrated Equipment Quick Turnaround Walk-in daily service 800 am-S 00 pm Send E-Mail to. PTWaters@junocom KMI 7420 Seven Mile Rd Northville Michigan 48167 Ph 810-486-4800 Fax 810-486-1603
Edition: Model Aviation - 1997/06
Page Numbers: 28, 29, 30, 37, 39, 41, 47, 48
MODEL AIRPLANES Its easy think says author father-andson test program yielded some interesting results 28 Model Aviation f Raskiri explaining term aspect ratio then-nine-year-old son Aza taking part ages-old tradition passing knowledge generation next gave him simple example rectangular wing aspect ratio span divided chord wing foot span foot chord would have aspect ratio . interrupted Right said span four feet . aspect ratio would befour said Aza showed him notate aspect ratios 11 41 talked about bigger wings could carry weightor same weight larger wing could fly slowly smaller wings Aza has flying lot model airplanes made sense him really tiny wing added airplane would have fly very fast stay up Right said pleased observation showed him picture F-104 its tiny wings goes very fast Aza asked question trying lead him think about What difference does aspect ratio make way airplane flies full-size airplanes answered higher aspect ratios make efficient can go farther less fuel example What kind airplanes have very high aspect ratios Aza has plastic models hanging ceiling home including some sailplanes Gliders said can go long ways fuel use thermais climb So dont people just make airplanes large aspect ratios What would look like asked wings would long skinny replied what problems would cause would flex too much especially high speeds would hard put hangars youd need very long ramp get airport would have left subject wanted know did say full-size airplanes Isnt true models too Well extemporized things bit complicated Its easy find out said Aza Lets just make two modelsone high aspect ratio low aspect ratio everything else same see flies better Azas proposal sounded reasonable no finer way get truth Wings quarter-chords aligned Wings centers same line June1997 29 Area4 sq in Span 8 Chord 05 Aspect Ratio 16 Area 4 sq Span 4 Chord 1 Aspect Ratio 4 Area 4 sq Span 2 Chord 2 Aspect Ratio 1 -U 0 well-designed experiment didnt have answer him since make chord wing small becomes less efficient Reynolds number effects works against gains increasing aspect ratio unlike full-scale airplanes Reynolds number effects usually important thought try explain Aza would bit much hed have take lot faith Aza could see test models would have identical could make changed aspect ratio would have keep area constant Aza studied area its relationship multiplication enough mathematics find rectangles same area different aspect ratios decided small simple balsa models wing area four square inches aspect ratio 11 wing would two inches two inches square wing suggested aspect ratio 161 soon drawn rectangle 1/2 inch eight inches long thin wing Another easy span four inches chord inch 41 aspect ratio suggested wing chord 11/2 inches think quite figure span came up number wrong answers before figuring out surprising him correct 10 2/3 inches never built last wing turned out decided wings could conveniently made A2 balsa consistency would just cut pieces square-edged round themjust like F North Pacific Guillow gliders often fly didnt discuss logically no difference between asking about effect aspect ratio effect span experiment could equally well describe wings going build having same areafour square inches spans two four eight inches found hobby shop bought sheet A2 x 2 x 36 balsa wings tail surfaces 1/8 x stick make fuselages little bottle cyanoacrylate CyA glue purchased assemble models stabilizer would 25% area wingour familys standard formula simple gliders made square inch Aza soon sketched out x 2 rectangle chose use twin-fin design since fins would stiffen stabilizer would very easy align fins /2 inch chord 3/4 inch height Aza already knew about using decalage give model pitch stability wanted some way make sure airplanes same amount So just built fuselage shape Three stabilizer/fin assemblies built attached bottom fuselage sticks using square assure straight line ruled across center stabilizer assured centered Things going well until asked should attach wings Aerodynamics texts tell us rectangular flat wing acts though its lift generated line /4 way front airfoil lifting line airfoil one-inch chord behind leading edge way build airplanes put quarter-chord points wings same position fuselage would change weight distribution models keep weight distribution same airfoils would have have centers same position fuselage fun see Aza ponder over concept lifting line something hadnt run before asked could demonstrate him couldnt think easy way demonstrate lifting-line concept Continued page 37 30 Model Aviation wing airfoil 62% 41 wing airfoil 31% 11 wing airfoil 15% End views three wings showing airfoils used scaled equal chord length wing awing b wing c wings b have same total dihedral wings c have same dihedral angle TestinglRaskin Continued page 30 seffled putting centers wings same place Pure experiments give clean answers very hard come aerodynamics business about proper location wings different aspect ratio fine example Airplanes quite sensitive position wing certainly unclear what right way proceed case built models anyway went backyard test fly rise some five feet Aza toss soft grass cushion landings nearly morning windless Dandelion fluffone favorite wind indicatorsdropped straight down two low-aspect-ratio airplanes flew well 161 model bit unstable decided some dihedral would beneficial next question much dihedral Should use same angle dihedral raise wingtips same distance pointed out raising same distance would make angle greater shorter wingssomething immediately clear Aza What does mean two wings different spans aspect ratios have same amount dihedral Again made arbitrary decision keep angle same choice hard justify physically assuming lift generated wing proportional its area like third-graders Aza isnt quite up trigonometry vector representation forces needed explanation trimming however able get 161 fly stably never added dihedral Another difference between models June1997 37 LIGHTING SYSTEMS THE ORIGINALS. Still Best RAM 01Adj Flash Nay Lights 9V NEW 94 spanWI wing light conn$2995 RAM 02Strobe Light 9V adjustable flash rate1995 RAM 03Landing Li9hts 48V receiver controlled3995 RAM 04Mars Rotating Beacon 9V adjustable rate1995 RAM 06 Sky Lights 18 Li9ht Set 72-9V 94 best way fly night 2995 RAM 14 Big Airplane Navi9ation Lights 9V 168 span non flashing2495 RAM 15 Non Flash Nay Lights 9 NEW 94 span w/ wing light conn 1495 RAM 16 Econo Landing Lights 9V servo controlled brightest . 1995 RAM 23 Real Strobe Li9ht 3V brightest.. 2995 RAM 65 T6 Lg Scale Lighting 72-9V Comb #s 04 14 & 16 100 span 5995 6 SEE YOUR DEALER SEND STAMPED ENVELOPE FOR RAM INFO unavailable locally send check money order full credit card info coat tern plus $400 l$50O foreigni immediate shipment Include full address U PS Sorry no cOD m 229B E Rollins Rd d Lake Beach IL 60073 Aza noticed amount wing covered fuselage greater lower-aspect-ratio wings fact area four times much 11 wing 161 wing significant another impurity experiment hard change just thing wings another major difference didnt discuss Aza thickness ratio airfoil determines lot about flies wings same thickness different chords Heres stack up Aspect Ratio 161 41 11 Thickness Ratio 62% 31% 15% know having studied aerodynamics anything given mean line under about 3% thickness ratio flies about same particularly sensitive Reynolds number 6% different matter Know quotes because am sure what have studied applies square-edged small airfoils case certainly using very different airfoils three models highest aspect ratio wing certainly has worst airfoil thickness ratio 161 wing four times thickness ratio 11 wing give wings same airfoil might choose make wings i/s tAs 1/82 wood does make less alike What does same same actual thickness same thickness ratio have read reports about effect changing aspect ratios often left unclear what airfoils used Perhaps models should scaled flying same Reynolds number different sizes wing chords same stabilizers will different sizes stabilizers will flying different June1997 39 KEEP FLYING THAT MODEL FOR YEARS BTA AUTO PILOT real Auto Pilot Designed back-up unit levels skill Inflight ON/OFF Switching Simple Plug Installation Sensors Internal & Unaffected External Conditions Consistent Operation Day Night Overcast Sunny Adjustable Zero & Gains Compatible RC Systems Endorsed Used Top Gun TOC Giant Scale Race Pilots & Experimental Full-Size also II-\--I 1001SEND IOVER 2000 TOOLS & ACCESSORIESFOR YOUR COPY Brand Names. Unusual Items.TODAY Exclusive Products savings up 60% designed make prolect Ieasier enjoyable professional I TO ORDER Send $100 coupon name address ADDRESS_____________________________________________________[v33][b231172014226250]] MlcroMerk 2249 Snyder AveI Berkeley Heights NJ 07922-1595CITYSTATE________ ZIPj B T Automatic Piloting Systems 192 Yorktown Lane a Mesa CA 92626 Phone 714-979-8948 714-979-8947 Send SASE Information Reynolds numbers perhaps affecting performance Again have ask what mean same Once models built weighed simple balance made leftover balsa added clay top center wing until weighed same Perhaps should have put clay centers gravity didnt know point yet now three airplanes sort same subject problems have listed perhaps others havent thought Now add nose weight until flew two ways could just test-fly add subtract clay nose until flew well possible some subjective criterion add remove clay center until weighed same again could balance same relative place say 30% wing chord Again have ask what same trimming Balancing 30% chord point disaster nose-heavy 50% point right either So trimmed trial-and-error reballasted equal weight Now would have ask trimmed optimally difficult part flight testing Ignoring problems have up now getting simple models same going make sure launched same will measure performance going eliminate biasespecially unconscious bias part Aza thought 41 wing would fly best looked normal wasnt sure 161 looked like sailplane worst airfoil undecided what expect also ask what better Ease launch speed straightness flight path Continued page 47 TRU-TURN now offers very finest versatile lightweight PROP HUBS turned solid barstock inside out true running hub new hub will mount motor standard TRU-TURN adapter kit big bird multi-bolt applications TRU-TURN has covered TRU-TURN also has PROP NUT will fit motor precision PROP NUTS come engine thread sizes two different shapes available stock Ask hobby dealer name ZI~ RMadenthe U S PRECISION MODEL PRODUCTS Romco Manufacturing Inc QUALITY VERSA TILITY T LOOKS TY PO Box 836 South Houston Texas 77587 713 943-1867 Z 1997 41 TestinglRaskin Continued page 41 what chose distance measure quality Aza has done lot flying has flown few contests including some hand-launched gliders could see value measure also technically reasonable since related directly glide angle equals lift-to-drag ratio flights start same height least reasonably easy Aza would launch high could reach agreed height wouldnt exactly same wed fly airplane number times troublesome wed get same launch speed Generally harder throw something farther will go isnt strictly true model airplanes hard launch might result loop example launch certainly affects distance Unconscious bias difficult factors deal Unconscious bias experimenter unintentionally makes experiment work way expects otherwise-careful scientists have gotten wrong results because unconscious bias factor what makes necessary blind experimentswhere tester does know factor being tested present medical work double blind experiments often used after results have tallied will experimenters know patient got what treatment what results did test demonstrates unconscious bias very effectively slope soarer operated computer radio often let other people fly threw switch box flying same time told made airplane bit responsive After few minutes asked much improved aileron elevator response flier reported some kind improvement Some said made small difference others said made large difference greatly improved handling found no difference June1997 47 IqI1v-ii New 97 engineers K&B manufacturing come three ingenious improvements have exclusively developed new K&B 61 ABC engine new Iwist head greatly improves engine performance reduces engine wear redesigned porting increases engine power AJso new tuned muffler design actually acts like tuned pipe increasing horsepower making engine run quieter over 50 years K&B Manufactung has leader quality US Mode hobby products continues tradition new K&B 61 ABC Will II PNDesCdptIon 4012-40 MInew/muffier 4075 40 ABC Sped Madne 510067 IliccI Inboard2t 5101 6711 lcd Outboard4011 / Muffler 5350 82 1132ccl Inboard4050- 40R/CA8Cw/Iuned Muffler 5375- 82 Ii 33cclOutboad5299-82 9/C Eluded Fur Heat Sink Headi 8702- 4517Sccl Outboard5250-829/CDucledFur 8907 -21 135cd1 Outboard5605-209/C Sporlufer 8916-21 13Sccllnboard5680-28R/CSpnrlster 9181- 4517ScdInbaard5805-65R/CSportsler 9575-10h164cclOutbaard5905-45R/CSpcinsler ENGIRS DSCR1PI1ON 6050- 61 R/CARC c/Tuned Muffler 6550-619/C w/Muffer 8910- 35cc 1fed Fan 9101- 1Scc[XrcledFun 9505- 1509/C RtHerow/Muffier 9549- 150 9/C Eluded Fan Heal Sink HeadJ 9550- 150R/CDucledFan 520 4533579 / 520453 3583 2100 College Dr. Lake Havasu Cftx ArIzona 86403 r-r,oH k&b@hio1ercor switch connected anything unconscious bias work aspect-ratio tests no way control unconscious bias unless built mechanical launcher still possibility wed unconsciously done better job trimming airplane thought would better measuring flight distance say nearest inch pull tape bit tighter model think will poorly mund up down borderline cases direction expected outcome can honest try cheat happens anyway studies have shown Results tests 11 seemed bestor least consistent achieving distance 41 seemed close second performance 11 single longest flight 161 usually worst Aza conectly concluded test good enough tell anything about effect aspect ratio glide Such conclusion loss Aza learned good experiment can very hard things dont always work clear-cut way youd like did design test eliminate unconscious bias Aza realized models consistenfly performed better others might because aspect ratio other factors slight warp would have build number model sort out accidental essential believe changes beloved designers cannot made isolation can nearly impossible set up experimentally sound testing procedure near-total lack blind testing cannot remember report model airplane experiment controlled unconscious bias Think carefully about claims read about model airplane design See conclusions really tested ask effect mentioned fact effect tesrei Ask yourseif unconscious bias might have present Few claims will pass tests askin 8 Gypsy Hill Rd Pac4fica CA 94044 48 Model Aviation twist-on head precision pin aligns piston sleeve eliminates stripped head bolts provides head torque reduces head leaks increases power increases performance reduces engine wear m increases engine Ilte RIC SERVICE AT ITS BEST AW~NL les Service Anything Radio Controlled Repairs Updates Custom Modifications Frequency Changes 6 Send Legal sized SAE 1997 Meter conversions ACE Airtronics Aristo-craft Cirrus EK Catalog containing lists RIC Futaba Hitec Heathkit Hobby Shack JR Kraft KGL KSE Kline maintenance hints Discover MCard VISA COD KoPropo Pro-Line RCD Tower Hobbies World Engines & others UPS USMAIL FED EX etc Calibrated Equipment Quick Turnaround Walk-in daily service 800 am-S 00 pm Send E-Mail to. PTWaters@junocom KMI 7420 Seven Mile Rd Northville Michigan 48167 Ph 810-486-4800 Fax 810-486-1603
