Simple Structural Test Techniques RC Aircraft Everyone wants design build airplanes safe flight conditions Ground testing per article others follow will tell story before plane gets air EGeorge M Myers NOTHING HAVE WRITTEN past 10 years has excited positive responses rapidly did offer April 1986 Radio Technique column describe simple structural test techniques model aircraft quote S3 Sierra Silent Soarers newsletter Oboyo boy George George! interested similar comments nice letters Fred E Bellows Jr Sharon MA Ken Gilpin Petersburg AK Ralph S Anderson Litchfield Park AZ Bobby R Pilldnton Columbia TN Bob Morris AMA 107933 Pete Van Dore Hobby Technics Elkins Park PA John Olden boom Plainfield NJ Duane Nelson Fair Oaks CA Paul R Adams Denver CO letters arrived first week after publication thanks kind words Our editor/publisher Carl Wheeley prefers deal subject separately Radio Technique lets get started Let say outset will demonstrating simplified procedures refinements possible used testing man-carrying aircraft refine ments expensive Im trying show procedures can followed very few special tools minimum expense doing things inexpensively no excuse doing carelessly thing worth doing worth doing right Test test things find hidden flaws build up confidence thing being tested save time money motto test engineer Get right answers purpose What test Four essential elements Vertical Sinking Speed Vacuum Versus Free Drop Distance IJropHt3 in67 in119in 186in 268in 365in4 ft5 ft Ft/Sec4681112141618 80 Model Aviation planes shown subjected drop tests up five feet collect data validate method show range aircraft can tested way Foreground Aquila Sailplane has skid weIghs 3 lb Behind L-R 9-lb Curare tricycle iand ing gearand 61 engIne 1 -lb Minimoustang two-wheel gearand1/aAengine 4-lb Spick lerGuicky 500with two-wheel gear 40 power Drop about5 ft simulates rough landings simple test setup using tape measL aEIU mu uumurruuuruurITurgrounaI IIUflU 15 Curare Pitch attitude stabilizing rod whun connected garbage can has disconnected George tests structures full-size aircraft part full-time job common eve ry test test speci men test loads test setup proce dure expect profit work will want some instrumenta tion can col lect test data have data should analyze Finally wont forget what happened should write self some kind report complete test begins test plan ends test report know want skip planning jump right testing Its dumb test way time just sake ex ample well begin simple test procedure testing drop airplane onto its landing gear test landing gear everything aircraft likely dam aged landing shock loads IL -pIur iIzipair ZI 2#NSe 2t831-P*ur 3pjjjK Proof load drop test Proof landing loads RC aircraft can generated free drop about 5 feet complete airplane landing attitude make statement basis sinking speeds used commercial military Navy aircraft teststaking account lightly-built RC aircraft will obtain support wings during fall therefore will land correspondingly lower vertical velocities height will full-size aircraft also take advantage fact small structures stronger large structures built same materials same manner Further Ive already performed tests sev eral own aircraft will see read Instrumentation have video cam era recorder slow playback and/or single-frame capability can learn some interesting things about airplane reacts same can done movie cameras understand what looking must know TV picture doesnt exist eyes fast enough would see thing call picture actually just spot flies back forth tracing horizontal paths TV screen takes spot 1/60th second trace other line screen lets call oddnumbered lines next 1/60th second spot traces evennumbered lines should now under stand can examine things take longer 1/30th second happen time takes construct complete TV frame display video frame drop test Continued page 157 ____________Hold 6 Release _ ______________Point Tank D Prop Horizontal Detaiis drop-test bridie simpie log decide con duct such tests means keep log examine video picture between drops make adjustments get appropriate ground con tact work up height small increments Goal such test ing determine have adequate structures safe flight August 198681 Photo TV screen taken ati35 1/30 sec Kodacoior400 after using slow motion find frame pause hold Shown Tim Myers Ouicky 500 during impact 2-ft drop about 11 ft/sec point gear totally coliapsed Re inforce landing gear considerations See text ThIs TV-screen photo example double image resulting interlace method building TV picture measuring wing tip blur knowing wing chord 18675 can estimate vertical velocity point fall However re member half blur belongs picture therefore distance traveled 1/60 sec half blur measure picture practice answer should 152 feet per second Georges Curare impact after 5-ft drop shown TVscreen photo retractable landing gear says has al ways taken much tinkering process bending back wont retract wheel wells can toil bythe bluron thetail plane already pitching back nose gear rebound Engine rework Youd better off spending time practicing racing pitting trying polish re-time soup intake restrictions new engine runs well anything else Ive seen Three-up Control Line Racing too much fun let slip away under horse power curve Quickie Rat captures excitement fun Racing does atmosphere promotes success appeals levels competitors would like hear anyone suggestions comments Frank Williams 710 Silverpines Houston TX 77062 phone 713-488-1371 Elec Champs/Naccarato Continued page 79 RC Old-Timer Seven-Cell 1 Paul Hingtgen Playboy Astro Co 05 7x800mAh Sanyo 2020 pts 2 Bob Sliff Playboy Astro Co 05 7x800mAh Sanyo 2008 pta 3 Larry Jolly Interceptor Aatro Co 05 7x800mAh Sanyo 1996 pta 4 Chuck Hollinger Nomad Astro Co 05 7x800mAh Sanyo 1865 pta 5 Jim Hall Playboy Leisure 05 7x800 mAl Sanyo 1860 pta RC Old-Timer Open 1 Mike Charles Super Quaker Aatro Co 60 26x800mAh Sanyo 2020 pta 2 Frank Chasteler Lanzo Keller 351 6x800 nAh Sanyo 2020 pta 3 Ross Thomas Lanzo Astro Co 40 26x800mAh Sanyo 2013 pta 4 Lowell Howe Sunduater Astro Co 251 6x800mAh Sanyo 1660 pta 5 Larry Jolly Interceptor Astro Co 05 7x800mAh Sanyo 1619 pta RC Stand-Off Scale 1 Bill Young Stephens Akro Aatro Co 60 3Oxl200mAh Sanyo 204 pta 2 Brian Chan Bede-5N Keller 25 l4xl200mAh Sanyo 177 pta 2 Ken Holcomb PorterfieldAatroSF 15 1 2x1 200mAh Sanyo 135 pta 3 Tony Naccarato J-3 Cub Astro Co 60 28xl200mAh Sanyo 129 pta 4 Bob Sliff Monocoupe Astro SF 40 18x l200mAh Sanyo 127 pta RC Aerobatics 1Steve Neu MKArrow Keller 50 14x1 200mAh GE 150 pta 2 Larry Jolly XC-40 Keller8O 26x1 200mAh GE 145 pta 4 Ed Depue Etude Astro 05 7x1 200mAh Sanyo 71 pta 4 Bob Sliff Snark Astro 05 7x1 200mAh Sanyo 50 pta RC Pylon Racing Seven-Cell 1 Larry Jolly Ohmen Astro Co 05 7x1 200mAh Sanyo 8 pta 2 Lowell Howe Fast Eddy Astro Co 05 7x1 200mAh Sanyo 6 pta 3 Mike Charles Avanti Keller 25 7xl200mAh GE 3 pta 4 Steve Neu original Keller 25 7xl200mAh Sanyo 3 pta Load Tests/Myers Continued page 81 frame will show two blurred images happens because TV image really made interlacing two pictures made 1/60th second apart described above Exposure time TV pic ture effectively 1/60th second movie camera can obtain similar formation double images since movie cameras make whole frame once Silent movies usually taken 18 frames per second sound movies taken 24 frames per second both exposed 1/40th second assuming using Kodachrome film Video USA always 30 frames per second interlaced described above movie camera has slow motion capability may get 36 54 frames per second shorter exposure like 1/90th 1/200th second Some home movie cam eras can synchronized strobe units light briefly 1/50000th second Short exposures can minimize blurring relative both TV image common movie camera exposure time 1/40th second Thats enough about simple instrumentation sample test drop testing airplane having performance characteristics akeady well known can accomplish two things can demonstrate method works can validate procedure convince correlation between what see test what see service preparing article made series free drops onto turf using Spickler Quicky 500 flown times built kit included stock wire landing gear videotape shows two feet drop height gear let belly fuselage hit ground plane bounced foot air hit again tail skid slammed down bounced couple times wheels Experienced Quicky 500 fliers will testify make such landing will indeed break prop After bouncing stopped landing gear rest plane looked undamaged except dents wheels went up through wing leading edge bottom sheeting same thing happened drops up five feet except belly hit harder prop turning would have broken just about drop test corresponds flight experiences Now would say landing gear passed failed drop test After repairing wing few times buying bunch props might decide stiffer landing gear would help situation course can land better wont have trouble Thus might might evaluate drop test results failure landing gear neither tore out airplane nor sep arated two loose pieces Given favorable landing conditions skillful pilot possible land Quicky 500 breaking prop Lots fliers discussion reader should also aware design aircraft model full-size mixture com promises ideal situation aspect may detrimental another Quicky 500 gear somewhat springy allows placing wheels near CG improved takeoffs opposite side coin very stiff landing gear might ripped off causing damage subjected landing condition type would make wheels dent Quicky 500 wing Regardiess evaluate landing gear would call successful proof test airplane wasnt broken testing over consider wing damage secondary dam age due flexibility landing August 1986 157 C C C U 1 I m z 0 z z C, 0 -a 0 -U m I m C- Q 0 0 -I CD U 0 0 C -00 C 0 U 0 Lij N CD 0 31 x 0 x N Plane cOnstructIOn models ghree large sheets parts shown full scale Weight down construction balsa plywood Models avaifable F 84-F Thunderatreak Sabre F 100 Super Saber SF16 Fighting Falcons F 15 Eagle Mirage 2000 21 Fishbed 71 Blackbird F 104 Start ighter Fit typee ducted fan anita wheel 5 dia 40 60 engines Available also motor ducted fan unit cunopy Price plan 5000 US dollars includes shipment air mail rolled lube Wlt free literature laformaf Ion G Bertella Via Matteotti 248 Gardone VT 25083 Brescia Italy 3W PACIFIC ACE 4 Complete kit $750 plus $150 S & H Also Rearwin Speedster Cessna 34Fairey Battle Fairchild Ranger & Lambert Monocoupe 30 Price $1000 Ea SEAGLEN MODEL CO BOX 123 Plympton MA 02367 gear results corresponded what demonstrated service would argue better find problem before decorate airplane drop testing loaded airframe perhaps could find problem two-foot drop height make proper repair continue five-foot drop height have lot better time flying plane afterward Should think springiness Quicky 500 problem flying skills instance might decide reinforcing underside wing sheeting wheels would hit hard landing would better solution substituting rigid gear Test procedures Start three-inch drop work way up table Measure drop height ground up bottom wheels time release examine videos airplane after drop actual vertical velocity contact will less given table because aerodynamic effects easier measure predict aerodynamic forces horizontal tail will rotate fuselage nose-down attitudemore like crash landingand must counteract rotation can example fasten long lightweight pole fuselage allow ing project rear Use far end pivot ground ensure plane hits ground proper flared landing attitude important thing sure weight pole isnt supported landing gear pole cant damage airplane used sixounce string arrows stabilize Minimoustang survived five-foot drops damage agrees service experience Minimoustang lightly-built pound 049-powered model Ive never trouble landing gear no matter badly plane handled arrows werent quite stiff enough control Minimoustang completed five-foot drops slightly nose-down attitude didnt get enough out line hit engine ground satisfied Another way control pitching tendency start model little nose high Use three-point suspension bridle made heavy thread get reproducible rigging angie support bridle singie loop thread will give clean release Start low drops observe results Keep increasing angie drop height increases dropped Curare retractable landing gear legs bent back enough wouldnt go wheel wellsas happens fly horizontal tail removable re place comparable weight will practically eliminate pitch changes during drop used approach droptesting Aquila usually fly over turf sol test over turf flying over pavement would carefully test over pavement Most likely would put down sheet plywood drop plane since pavement abrasive may wondering simulate effects uneven terrain rearward load tires generate landing drop-testing Navy aircraft spin wheels backward correct rpm simulate touchdown land specially-prepared steel plates also apply upward load wings simu lating lift equal 2/3 weight aircraft dont think refinements necessary RC model proof drop test Besides its pretty hard accurately simulate landing chuck hole use bridle technique set up landing angies testing full-size air craft dont use pivot arm because dont need dealing wing loadings 40 pounds per square foot RC models have loadings range half two pounds per square foot can change attitude considerably half-second takes fall five feet other hand have personally applied vertical velocities excess 35 ft/sec measurement attempting break Navy landing gear Grumman aircraft full-size airplanes begin fly So have make compen sations Have validated drop test mind Next time well take up static tests wings meantime now thinking seriously about test program new Quarter Scale model before pass ing plans around can obtain video tape drop tests sending $25 address below dont guarantee performing test others expect write about future will provide answers seems logical doing something has better doing nothing wont get professionalquality tape think its pretty good example home video tape contains additional information primarily way detail also contains visual evidence did what said did validate method George M Myers 70 Froehlich Farm Rd Hicksville NY 11801 QN/Cowley Continued page 90 square C-channel spar designed stiff spanwise bending yet remain flexible torsion Predicting exact character istics spar through analysis allowing spanwise lift distribution influenced flowing changes wing chord proved major undertaking goal develop structure would auto matically respond changing torsional loads producing appropriate wing twist distribution Lift membrane wing covering transferred spar again nature provided valuable clues Chordwise 158 Model Aviation RC SOARING DIGEST monthly publication COVCI fig International PC Soaring Scene SI 6lyearin USA US $20/yr Canada& Mexico US $24/yr elsewhere via airmail RCSD PO Box 269 Peterborough NH 03458 Far 020 Engines Free-Flight Rubber Pulse small Multi Channel R/C systems suitable 50 years ago vary capable aircraft ft well proportioned stable modal flight lotarestieg $2295 design landieg itself balsa structural techngaes KIT#102 WOce got chore 01 fauoritas Please send Finlire Caralog Ptroro 17031 2739593 DoaarsonO EIsrrihutoro ore nodal FLYLINE MODELS INC PO Bax 2136 Fairfax Virginia 22031 Full Size Plans Ducted Fans 1
Edition: Model Aviation - 1986/08
Page Numbers: 80, 81, 157, 158
Simple Structural Test Techniques RC Aircraft Everyone wants design build airplanes safe flight conditions Ground testing per article others follow will tell story before plane gets air EGeorge M Myers NOTHING HAVE WRITTEN past 10 years has excited positive responses rapidly did offer April 1986 Radio Technique column describe simple structural test techniques model aircraft quote S3 Sierra Silent Soarers newsletter Oboyo boy George George! interested similar comments nice letters Fred E Bellows Jr Sharon MA Ken Gilpin Petersburg AK Ralph S Anderson Litchfield Park AZ Bobby R Pilldnton Columbia TN Bob Morris AMA 107933 Pete Van Dore Hobby Technics Elkins Park PA John Olden boom Plainfield NJ Duane Nelson Fair Oaks CA Paul R Adams Denver CO letters arrived first week after publication thanks kind words Our editor/publisher Carl Wheeley prefers deal subject separately Radio Technique lets get started Let say outset will demonstrating simplified procedures refinements possible used testing man-carrying aircraft refine ments expensive Im trying show procedures can followed very few special tools minimum expense doing things inexpensively no excuse doing carelessly thing worth doing worth doing right Test test things find hidden flaws build up confidence thing being tested save time money motto test engineer Get right answers purpose What test Four essential elements Vertical Sinking Speed Vacuum Versus Free Drop Distance IJropHt3 in67 in119in 186in 268in 365in4 ft5 ft Ft/Sec4681112141618 80 Model Aviation planes shown subjected drop tests up five feet collect data validate method show range aircraft can tested way Foreground Aquila Sailplane has skid weIghs 3 lb Behind L-R 9-lb Curare tricycle iand ing gearand 61 engIne 1 -lb Minimoustang two-wheel gearand1/aAengine 4-lb Spick lerGuicky 500with two-wheel gear 40 power Drop about5 ft simulates rough landings simple test setup using tape measL aEIU mu uumurruuuruurITurgrounaI IIUflU 15 Curare Pitch attitude stabilizing rod whun connected garbage can has disconnected George tests structures full-size aircraft part full-time job common eve ry test test speci men test loads test setup proce dure expect profit work will want some instrumenta tion can col lect test data have data should analyze Finally wont forget what happened should write self some kind report complete test begins test plan ends test report know want skip planning jump right testing Its dumb test way time just sake ex ample well begin simple test procedure testing drop airplane onto its landing gear test landing gear everything aircraft likely dam aged landing shock loads IL -pIur iIzipair ZI 2#NSe 2t831-P*ur 3pjjjK Proof load drop test Proof landing loads RC aircraft can generated free drop about 5 feet complete airplane landing attitude make statement basis sinking speeds used commercial military Navy aircraft teststaking account lightly-built RC aircraft will obtain support wings during fall therefore will land correspondingly lower vertical velocities height will full-size aircraft also take advantage fact small structures stronger large structures built same materials same manner Further Ive already performed tests sev eral own aircraft will see read Instrumentation have video cam era recorder slow playback and/or single-frame capability can learn some interesting things about airplane reacts same can done movie cameras understand what looking must know TV picture doesnt exist eyes fast enough would see thing call picture actually just spot flies back forth tracing horizontal paths TV screen takes spot 1/60th second trace other line screen lets call oddnumbered lines next 1/60th second spot traces evennumbered lines should now under stand can examine things take longer 1/30th second happen time takes construct complete TV frame display video frame drop test Continued page 157 ____________Hold 6 Release _ ______________Point Tank D Prop Horizontal Detaiis drop-test bridie simpie log decide con duct such tests means keep log examine video picture between drops make adjustments get appropriate ground con tact work up height small increments Goal such test ing determine have adequate structures safe flight August 198681 Photo TV screen taken ati35 1/30 sec Kodacoior400 after using slow motion find frame pause hold Shown Tim Myers Ouicky 500 during impact 2-ft drop about 11 ft/sec point gear totally coliapsed Re inforce landing gear considerations See text ThIs TV-screen photo example double image resulting interlace method building TV picture measuring wing tip blur knowing wing chord 18675 can estimate vertical velocity point fall However re member half blur belongs picture therefore distance traveled 1/60 sec half blur measure picture practice answer should 152 feet per second Georges Curare impact after 5-ft drop shown TVscreen photo retractable landing gear says has al ways taken much tinkering process bending back wont retract wheel wells can toil bythe bluron thetail plane already pitching back nose gear rebound Engine rework Youd better off spending time practicing racing pitting trying polish re-time soup intake restrictions new engine runs well anything else Ive seen Three-up Control Line Racing too much fun let slip away under horse power curve Quickie Rat captures excitement fun Racing does atmosphere promotes success appeals levels competitors would like hear anyone suggestions comments Frank Williams 710 Silverpines Houston TX 77062 phone 713-488-1371 Elec Champs/Naccarato Continued page 79 RC Old-Timer Seven-Cell 1 Paul Hingtgen Playboy Astro Co 05 7x800mAh Sanyo 2020 pts 2 Bob Sliff Playboy Astro Co 05 7x800mAh Sanyo 2008 pta 3 Larry Jolly Interceptor Aatro Co 05 7x800mAh Sanyo 1996 pta 4 Chuck Hollinger Nomad Astro Co 05 7x800mAh Sanyo 1865 pta 5 Jim Hall Playboy Leisure 05 7x800 mAl Sanyo 1860 pta RC Old-Timer Open 1 Mike Charles Super Quaker Aatro Co 60 26x800mAh Sanyo 2020 pta 2 Frank Chasteler Lanzo Keller 351 6x800 nAh Sanyo 2020 pta 3 Ross Thomas Lanzo Astro Co 40 26x800mAh Sanyo 2013 pta 4 Lowell Howe Sunduater Astro Co 251 6x800mAh Sanyo 1660 pta 5 Larry Jolly Interceptor Astro Co 05 7x800mAh Sanyo 1619 pta RC Stand-Off Scale 1 Bill Young Stephens Akro Aatro Co 60 3Oxl200mAh Sanyo 204 pta 2 Brian Chan Bede-5N Keller 25 l4xl200mAh Sanyo 177 pta 2 Ken Holcomb PorterfieldAatroSF 15 1 2x1 200mAh Sanyo 135 pta 3 Tony Naccarato J-3 Cub Astro Co 60 28xl200mAh Sanyo 129 pta 4 Bob Sliff Monocoupe Astro SF 40 18x l200mAh Sanyo 127 pta RC Aerobatics 1Steve Neu MKArrow Keller 50 14x1 200mAh GE 150 pta 2 Larry Jolly XC-40 Keller8O 26x1 200mAh GE 145 pta 4 Ed Depue Etude Astro 05 7x1 200mAh Sanyo 71 pta 4 Bob Sliff Snark Astro 05 7x1 200mAh Sanyo 50 pta RC Pylon Racing Seven-Cell 1 Larry Jolly Ohmen Astro Co 05 7x1 200mAh Sanyo 8 pta 2 Lowell Howe Fast Eddy Astro Co 05 7x1 200mAh Sanyo 6 pta 3 Mike Charles Avanti Keller 25 7xl200mAh GE 3 pta 4 Steve Neu original Keller 25 7xl200mAh Sanyo 3 pta Load Tests/Myers Continued page 81 frame will show two blurred images happens because TV image really made interlacing two pictures made 1/60th second apart described above Exposure time TV pic ture effectively 1/60th second movie camera can obtain similar formation double images since movie cameras make whole frame once Silent movies usually taken 18 frames per second sound movies taken 24 frames per second both exposed 1/40th second assuming using Kodachrome film Video USA always 30 frames per second interlaced described above movie camera has slow motion capability may get 36 54 frames per second shorter exposure like 1/90th 1/200th second Some home movie cam eras can synchronized strobe units light briefly 1/50000th second Short exposures can minimize blurring relative both TV image common movie camera exposure time 1/40th second Thats enough about simple instrumentation sample test drop testing airplane having performance characteristics akeady well known can accomplish two things can demonstrate method works can validate procedure convince correlation between what see test what see service preparing article made series free drops onto turf using Spickler Quicky 500 flown times built kit included stock wire landing gear videotape shows two feet drop height gear let belly fuselage hit ground plane bounced foot air hit again tail skid slammed down bounced couple times wheels Experienced Quicky 500 fliers will testify make such landing will indeed break prop After bouncing stopped landing gear rest plane looked undamaged except dents wheels went up through wing leading edge bottom sheeting same thing happened drops up five feet except belly hit harder prop turning would have broken just about drop test corresponds flight experiences Now would say landing gear passed failed drop test After repairing wing few times buying bunch props might decide stiffer landing gear would help situation course can land better wont have trouble Thus might might evaluate drop test results failure landing gear neither tore out airplane nor sep arated two loose pieces Given favorable landing conditions skillful pilot possible land Quicky 500 breaking prop Lots fliers discussion reader should also aware design aircraft model full-size mixture com promises ideal situation aspect may detrimental another Quicky 500 gear somewhat springy allows placing wheels near CG improved takeoffs opposite side coin very stiff landing gear might ripped off causing damage subjected landing condition type would make wheels dent Quicky 500 wing Regardiess evaluate landing gear would call successful proof test airplane wasnt broken testing over consider wing damage secondary dam age due flexibility landing August 1986 157 C C C U 1 I m z 0 z z C, 0 -a 0 -U m I m C- Q 0 0 -I CD U 0 0 C -00 C 0 U 0 Lij N CD 0 31 x 0 x N Plane cOnstructIOn models ghree large sheets parts shown full scale Weight down construction balsa plywood Models avaifable F 84-F Thunderatreak Sabre F 100 Super Saber SF16 Fighting Falcons F 15 Eagle Mirage 2000 21 Fishbed 71 Blackbird F 104 Start ighter Fit typee ducted fan anita wheel 5 dia 40 60 engines Available also motor ducted fan unit cunopy Price plan 5000 US dollars includes shipment air mail rolled lube Wlt free literature laformaf Ion G Bertella Via Matteotti 248 Gardone VT 25083 Brescia Italy 3W PACIFIC ACE 4 Complete kit $750 plus $150 S & H Also Rearwin Speedster Cessna 34Fairey Battle Fairchild Ranger & Lambert Monocoupe 30 Price $1000 Ea SEAGLEN MODEL CO BOX 123 Plympton MA 02367 gear results corresponded what demonstrated service would argue better find problem before decorate airplane drop testing loaded airframe perhaps could find problem two-foot drop height make proper repair continue five-foot drop height have lot better time flying plane afterward Should think springiness Quicky 500 problem flying skills instance might decide reinforcing underside wing sheeting wheels would hit hard landing would better solution substituting rigid gear Test procedures Start three-inch drop work way up table Measure drop height ground up bottom wheels time release examine videos airplane after drop actual vertical velocity contact will less given table because aerodynamic effects easier measure predict aerodynamic forces horizontal tail will rotate fuselage nose-down attitudemore like crash landingand must counteract rotation can example fasten long lightweight pole fuselage allow ing project rear Use far end pivot ground ensure plane hits ground proper flared landing attitude important thing sure weight pole isnt supported landing gear pole cant damage airplane used sixounce string arrows stabilize Minimoustang survived five-foot drops damage agrees service experience Minimoustang lightly-built pound 049-powered model Ive never trouble landing gear no matter badly plane handled arrows werent quite stiff enough control Minimoustang completed five-foot drops slightly nose-down attitude didnt get enough out line hit engine ground satisfied Another way control pitching tendency start model little nose high Use three-point suspension bridle made heavy thread get reproducible rigging angie support bridle singie loop thread will give clean release Start low drops observe results Keep increasing angie drop height increases dropped Curare retractable landing gear legs bent back enough wouldnt go wheel wellsas happens fly horizontal tail removable re place comparable weight will practically eliminate pitch changes during drop used approach droptesting Aquila usually fly over turf sol test over turf flying over pavement would carefully test over pavement Most likely would put down sheet plywood drop plane since pavement abrasive may wondering simulate effects uneven terrain rearward load tires generate landing drop-testing Navy aircraft spin wheels backward correct rpm simulate touchdown land specially-prepared steel plates also apply upward load wings simu lating lift equal 2/3 weight aircraft dont think refinements necessary RC model proof drop test Besides its pretty hard accurately simulate landing chuck hole use bridle technique set up landing angies testing full-size air craft dont use pivot arm because dont need dealing wing loadings 40 pounds per square foot RC models have loadings range half two pounds per square foot can change attitude considerably half-second takes fall five feet other hand have personally applied vertical velocities excess 35 ft/sec measurement attempting break Navy landing gear Grumman aircraft full-size airplanes begin fly So have make compen sations Have validated drop test mind Next time well take up static tests wings meantime now thinking seriously about test program new Quarter Scale model before pass ing plans around can obtain video tape drop tests sending $25 address below dont guarantee performing test others expect write about future will provide answers seems logical doing something has better doing nothing wont get professionalquality tape think its pretty good example home video tape contains additional information primarily way detail also contains visual evidence did what said did validate method George M Myers 70 Froehlich Farm Rd Hicksville NY 11801 QN/Cowley Continued page 90 square C-channel spar designed stiff spanwise bending yet remain flexible torsion Predicting exact character istics spar through analysis allowing spanwise lift distribution influenced flowing changes wing chord proved major undertaking goal develop structure would auto matically respond changing torsional loads producing appropriate wing twist distribution Lift membrane wing covering transferred spar again nature provided valuable clues Chordwise 158 Model Aviation RC SOARING DIGEST monthly publication COVCI fig International PC Soaring Scene SI 6lyearin USA US $20/yr Canada& Mexico US $24/yr elsewhere via airmail RCSD PO Box 269 Peterborough NH 03458 Far 020 Engines Free-Flight Rubber Pulse small Multi Channel R/C systems suitable 50 years ago vary capable aircraft ft well proportioned stable modal flight lotarestieg $2295 design landieg itself balsa structural techngaes KIT#102 WOce got chore 01 fauoritas Please send Finlire Caralog Ptroro 17031 2739593 DoaarsonO EIsrrihutoro ore nodal FLYLINE MODELS INC PO Bax 2136 Fairfax Virginia 22031 Full Size Plans Ducted Fans 1
Edition: Model Aviation - 1986/08
Page Numbers: 80, 81, 157, 158
Simple Structural Test Techniques RC Aircraft Everyone wants design build airplanes safe flight conditions Ground testing per article others follow will tell story before plane gets air EGeorge M Myers NOTHING HAVE WRITTEN past 10 years has excited positive responses rapidly did offer April 1986 Radio Technique column describe simple structural test techniques model aircraft quote S3 Sierra Silent Soarers newsletter Oboyo boy George George! interested similar comments nice letters Fred E Bellows Jr Sharon MA Ken Gilpin Petersburg AK Ralph S Anderson Litchfield Park AZ Bobby R Pilldnton Columbia TN Bob Morris AMA 107933 Pete Van Dore Hobby Technics Elkins Park PA John Olden boom Plainfield NJ Duane Nelson Fair Oaks CA Paul R Adams Denver CO letters arrived first week after publication thanks kind words Our editor/publisher Carl Wheeley prefers deal subject separately Radio Technique lets get started Let say outset will demonstrating simplified procedures refinements possible used testing man-carrying aircraft refine ments expensive Im trying show procedures can followed very few special tools minimum expense doing things inexpensively no excuse doing carelessly thing worth doing worth doing right Test test things find hidden flaws build up confidence thing being tested save time money motto test engineer Get right answers purpose What test Four essential elements Vertical Sinking Speed Vacuum Versus Free Drop Distance IJropHt3 in67 in119in 186in 268in 365in4 ft5 ft Ft/Sec4681112141618 80 Model Aviation planes shown subjected drop tests up five feet collect data validate method show range aircraft can tested way Foreground Aquila Sailplane has skid weIghs 3 lb Behind L-R 9-lb Curare tricycle iand ing gearand 61 engIne 1 -lb Minimoustang two-wheel gearand1/aAengine 4-lb Spick lerGuicky 500with two-wheel gear 40 power Drop about5 ft simulates rough landings simple test setup using tape measL aEIU mu uumurruuuruurITurgrounaI IIUflU 15 Curare Pitch attitude stabilizing rod whun connected garbage can has disconnected George tests structures full-size aircraft part full-time job common eve ry test test speci men test loads test setup proce dure expect profit work will want some instrumenta tion can col lect test data have data should analyze Finally wont forget what happened should write self some kind report complete test begins test plan ends test report know want skip planning jump right testing Its dumb test way time just sake ex ample well begin simple test procedure testing drop airplane onto its landing gear test landing gear everything aircraft likely dam aged landing shock loads IL -pIur iIzipair ZI 2#NSe 2t831-P*ur 3pjjjK Proof load drop test Proof landing loads RC aircraft can generated free drop about 5 feet complete airplane landing attitude make statement basis sinking speeds used commercial military Navy aircraft teststaking account lightly-built RC aircraft will obtain support wings during fall therefore will land correspondingly lower vertical velocities height will full-size aircraft also take advantage fact small structures stronger large structures built same materials same manner Further Ive already performed tests sev eral own aircraft will see read Instrumentation have video cam era recorder slow playback and/or single-frame capability can learn some interesting things about airplane reacts same can done movie cameras understand what looking must know TV picture doesnt exist eyes fast enough would see thing call picture actually just spot flies back forth tracing horizontal paths TV screen takes spot 1/60th second trace other line screen lets call oddnumbered lines next 1/60th second spot traces evennumbered lines should now under stand can examine things take longer 1/30th second happen time takes construct complete TV frame display video frame drop test Continued page 157 ____________Hold 6 Release _ ______________Point Tank D Prop Horizontal Detaiis drop-test bridie simpie log decide con duct such tests means keep log examine video picture between drops make adjustments get appropriate ground con tact work up height small increments Goal such test ing determine have adequate structures safe flight August 198681 Photo TV screen taken ati35 1/30 sec Kodacoior400 after using slow motion find frame pause hold Shown Tim Myers Ouicky 500 during impact 2-ft drop about 11 ft/sec point gear totally coliapsed Re inforce landing gear considerations See text ThIs TV-screen photo example double image resulting interlace method building TV picture measuring wing tip blur knowing wing chord 18675 can estimate vertical velocity point fall However re member half blur belongs picture therefore distance traveled 1/60 sec half blur measure picture practice answer should 152 feet per second Georges Curare impact after 5-ft drop shown TVscreen photo retractable landing gear says has al ways taken much tinkering process bending back wont retract wheel wells can toil bythe bluron thetail plane already pitching back nose gear rebound Engine rework Youd better off spending time practicing racing pitting trying polish re-time soup intake restrictions new engine runs well anything else Ive seen Three-up Control Line Racing too much fun let slip away under horse power curve Quickie Rat captures excitement fun Racing does atmosphere promotes success appeals levels competitors would like hear anyone suggestions comments Frank Williams 710 Silverpines Houston TX 77062 phone 713-488-1371 Elec Champs/Naccarato Continued page 79 RC Old-Timer Seven-Cell 1 Paul Hingtgen Playboy Astro Co 05 7x800mAh Sanyo 2020 pts 2 Bob Sliff Playboy Astro Co 05 7x800mAh Sanyo 2008 pta 3 Larry Jolly Interceptor Aatro Co 05 7x800mAh Sanyo 1996 pta 4 Chuck Hollinger Nomad Astro Co 05 7x800mAh Sanyo 1865 pta 5 Jim Hall Playboy Leisure 05 7x800 mAl Sanyo 1860 pta RC Old-Timer Open 1 Mike Charles Super Quaker Aatro Co 60 26x800mAh Sanyo 2020 pta 2 Frank Chasteler Lanzo Keller 351 6x800 nAh Sanyo 2020 pta 3 Ross Thomas Lanzo Astro Co 40 26x800mAh Sanyo 2013 pta 4 Lowell Howe Sunduater Astro Co 251 6x800mAh Sanyo 1660 pta 5 Larry Jolly Interceptor Astro Co 05 7x800mAh Sanyo 1619 pta RC Stand-Off Scale 1 Bill Young Stephens Akro Aatro Co 60 3Oxl200mAh Sanyo 204 pta 2 Brian Chan Bede-5N Keller 25 l4xl200mAh Sanyo 177 pta 2 Ken Holcomb PorterfieldAatroSF 15 1 2x1 200mAh Sanyo 135 pta 3 Tony Naccarato J-3 Cub Astro Co 60 28xl200mAh Sanyo 129 pta 4 Bob Sliff Monocoupe Astro SF 40 18x l200mAh Sanyo 127 pta RC Aerobatics 1Steve Neu MKArrow Keller 50 14x1 200mAh GE 150 pta 2 Larry Jolly XC-40 Keller8O 26x1 200mAh GE 145 pta 4 Ed Depue Etude Astro 05 7x1 200mAh Sanyo 71 pta 4 Bob Sliff Snark Astro 05 7x1 200mAh Sanyo 50 pta RC Pylon Racing Seven-Cell 1 Larry Jolly Ohmen Astro Co 05 7x1 200mAh Sanyo 8 pta 2 Lowell Howe Fast Eddy Astro Co 05 7x1 200mAh Sanyo 6 pta 3 Mike Charles Avanti Keller 25 7xl200mAh GE 3 pta 4 Steve Neu original Keller 25 7xl200mAh Sanyo 3 pta Load Tests/Myers Continued page 81 frame will show two blurred images happens because TV image really made interlacing two pictures made 1/60th second apart described above Exposure time TV pic ture effectively 1/60th second movie camera can obtain similar formation double images since movie cameras make whole frame once Silent movies usually taken 18 frames per second sound movies taken 24 frames per second both exposed 1/40th second assuming using Kodachrome film Video USA always 30 frames per second interlaced described above movie camera has slow motion capability may get 36 54 frames per second shorter exposure like 1/90th 1/200th second Some home movie cam eras can synchronized strobe units light briefly 1/50000th second Short exposures can minimize blurring relative both TV image common movie camera exposure time 1/40th second Thats enough about simple instrumentation sample test drop testing airplane having performance characteristics akeady well known can accomplish two things can demonstrate method works can validate procedure convince correlation between what see test what see service preparing article made series free drops onto turf using Spickler Quicky 500 flown times built kit included stock wire landing gear videotape shows two feet drop height gear let belly fuselage hit ground plane bounced foot air hit again tail skid slammed down bounced couple times wheels Experienced Quicky 500 fliers will testify make such landing will indeed break prop After bouncing stopped landing gear rest plane looked undamaged except dents wheels went up through wing leading edge bottom sheeting same thing happened drops up five feet except belly hit harder prop turning would have broken just about drop test corresponds flight experiences Now would say landing gear passed failed drop test After repairing wing few times buying bunch props might decide stiffer landing gear would help situation course can land better wont have trouble Thus might might evaluate drop test results failure landing gear neither tore out airplane nor sep arated two loose pieces Given favorable landing conditions skillful pilot possible land Quicky 500 breaking prop Lots fliers discussion reader should also aware design aircraft model full-size mixture com promises ideal situation aspect may detrimental another Quicky 500 gear somewhat springy allows placing wheels near CG improved takeoffs opposite side coin very stiff landing gear might ripped off causing damage subjected landing condition type would make wheels dent Quicky 500 wing Regardiess evaluate landing gear would call successful proof test airplane wasnt broken testing over consider wing damage secondary dam age due flexibility landing August 1986 157 C C C U 1 I m z 0 z z C, 0 -a 0 -U m I m C- Q 0 0 -I CD U 0 0 C -00 C 0 U 0 Lij N CD 0 31 x 0 x N Plane cOnstructIOn models ghree large sheets parts shown full scale Weight down construction balsa plywood Models avaifable F 84-F Thunderatreak Sabre F 100 Super Saber SF16 Fighting Falcons F 15 Eagle Mirage 2000 21 Fishbed 71 Blackbird F 104 Start ighter Fit typee ducted fan anita wheel 5 dia 40 60 engines Available also motor ducted fan unit cunopy Price plan 5000 US dollars includes shipment air mail rolled lube Wlt free literature laformaf Ion G Bertella Via Matteotti 248 Gardone VT 25083 Brescia Italy 3W PACIFIC ACE 4 Complete kit $750 plus $150 S & H Also Rearwin Speedster Cessna 34Fairey Battle Fairchild Ranger & Lambert Monocoupe 30 Price $1000 Ea SEAGLEN MODEL CO BOX 123 Plympton MA 02367 gear results corresponded what demonstrated service would argue better find problem before decorate airplane drop testing loaded airframe perhaps could find problem two-foot drop height make proper repair continue five-foot drop height have lot better time flying plane afterward Should think springiness Quicky 500 problem flying skills instance might decide reinforcing underside wing sheeting wheels would hit hard landing would better solution substituting rigid gear Test procedures Start three-inch drop work way up table Measure drop height ground up bottom wheels time release examine videos airplane after drop actual vertical velocity contact will less given table because aerodynamic effects easier measure predict aerodynamic forces horizontal tail will rotate fuselage nose-down attitudemore like crash landingand must counteract rotation can example fasten long lightweight pole fuselage allow ing project rear Use far end pivot ground ensure plane hits ground proper flared landing attitude important thing sure weight pole isnt supported landing gear pole cant damage airplane used sixounce string arrows stabilize Minimoustang survived five-foot drops damage agrees service experience Minimoustang lightly-built pound 049-powered model Ive never trouble landing gear no matter badly plane handled arrows werent quite stiff enough control Minimoustang completed five-foot drops slightly nose-down attitude didnt get enough out line hit engine ground satisfied Another way control pitching tendency start model little nose high Use three-point suspension bridle made heavy thread get reproducible rigging angie support bridle singie loop thread will give clean release Start low drops observe results Keep increasing angie drop height increases dropped Curare retractable landing gear legs bent back enough wouldnt go wheel wellsas happens fly horizontal tail removable re place comparable weight will practically eliminate pitch changes during drop used approach droptesting Aquila usually fly over turf sol test over turf flying over pavement would carefully test over pavement Most likely would put down sheet plywood drop plane since pavement abrasive may wondering simulate effects uneven terrain rearward load tires generate landing drop-testing Navy aircraft spin wheels backward correct rpm simulate touchdown land specially-prepared steel plates also apply upward load wings simu lating lift equal 2/3 weight aircraft dont think refinements necessary RC model proof drop test Besides its pretty hard accurately simulate landing chuck hole use bridle technique set up landing angies testing full-size air craft dont use pivot arm because dont need dealing wing loadings 40 pounds per square foot RC models have loadings range half two pounds per square foot can change attitude considerably half-second takes fall five feet other hand have personally applied vertical velocities excess 35 ft/sec measurement attempting break Navy landing gear Grumman aircraft full-size airplanes begin fly So have make compen sations Have validated drop test mind Next time well take up static tests wings meantime now thinking seriously about test program new Quarter Scale model before pass ing plans around can obtain video tape drop tests sending $25 address below dont guarantee performing test others expect write about future will provide answers seems logical doing something has better doing nothing wont get professionalquality tape think its pretty good example home video tape contains additional information primarily way detail also contains visual evidence did what said did validate method George M Myers 70 Froehlich Farm Rd Hicksville NY 11801 QN/Cowley Continued page 90 square C-channel spar designed stiff spanwise bending yet remain flexible torsion Predicting exact character istics spar through analysis allowing spanwise lift distribution influenced flowing changes wing chord proved major undertaking goal develop structure would auto matically respond changing torsional loads producing appropriate wing twist distribution Lift membrane wing covering transferred spar again nature provided valuable clues Chordwise 158 Model Aviation RC SOARING DIGEST monthly publication COVCI fig International PC Soaring Scene SI 6lyearin USA US $20/yr Canada& Mexico US $24/yr elsewhere via airmail RCSD PO Box 269 Peterborough NH 03458 Far 020 Engines Free-Flight Rubber Pulse small Multi Channel R/C systems suitable 50 years ago vary capable aircraft ft well proportioned stable modal flight lotarestieg $2295 design landieg itself balsa structural techngaes KIT#102 WOce got chore 01 fauoritas Please send Finlire Caralog Ptroro 17031 2739593 DoaarsonO EIsrrihutoro ore nodal FLYLINE MODELS INC PO Bax 2136 Fairfax Virginia 22031 Full Size Plans Ducted Fans 1
Edition: Model Aviation - 1986/08
Page Numbers: 80, 81, 157, 158
Simple Structural Test Techniques RC Aircraft Everyone wants design build airplanes safe flight conditions Ground testing per article others follow will tell story before plane gets air EGeorge M Myers NOTHING HAVE WRITTEN past 10 years has excited positive responses rapidly did offer April 1986 Radio Technique column describe simple structural test techniques model aircraft quote S3 Sierra Silent Soarers newsletter Oboyo boy George George! interested similar comments nice letters Fred E Bellows Jr Sharon MA Ken Gilpin Petersburg AK Ralph S Anderson Litchfield Park AZ Bobby R Pilldnton Columbia TN Bob Morris AMA 107933 Pete Van Dore Hobby Technics Elkins Park PA John Olden boom Plainfield NJ Duane Nelson Fair Oaks CA Paul R Adams Denver CO letters arrived first week after publication thanks kind words Our editor/publisher Carl Wheeley prefers deal subject separately Radio Technique lets get started Let say outset will demonstrating simplified procedures refinements possible used testing man-carrying aircraft refine ments expensive Im trying show procedures can followed very few special tools minimum expense doing things inexpensively no excuse doing carelessly thing worth doing worth doing right Test test things find hidden flaws build up confidence thing being tested save time money motto test engineer Get right answers purpose What test Four essential elements Vertical Sinking Speed Vacuum Versus Free Drop Distance IJropHt3 in67 in119in 186in 268in 365in4 ft5 ft Ft/Sec4681112141618 80 Model Aviation planes shown subjected drop tests up five feet collect data validate method show range aircraft can tested way Foreground Aquila Sailplane has skid weIghs 3 lb Behind L-R 9-lb Curare tricycle iand ing gearand 61 engIne 1 -lb Minimoustang two-wheel gearand1/aAengine 4-lb Spick lerGuicky 500with two-wheel gear 40 power Drop about5 ft simulates rough landings simple test setup using tape measL aEIU mu uumurruuuruurITurgrounaI IIUflU 15 Curare Pitch attitude stabilizing rod whun connected garbage can has disconnected George tests structures full-size aircraft part full-time job common eve ry test test speci men test loads test setup proce dure expect profit work will want some instrumenta tion can col lect test data have data should analyze Finally wont forget what happened should write self some kind report complete test begins test plan ends test report know want skip planning jump right testing Its dumb test way time just sake ex ample well begin simple test procedure testing drop airplane onto its landing gear test landing gear everything aircraft likely dam aged landing shock loads IL -pIur iIzipair ZI 2#NSe 2t831-P*ur 3pjjjK Proof load drop test Proof landing loads RC aircraft can generated free drop about 5 feet complete airplane landing attitude make statement basis sinking speeds used commercial military Navy aircraft teststaking account lightly-built RC aircraft will obtain support wings during fall therefore will land correspondingly lower vertical velocities height will full-size aircraft also take advantage fact small structures stronger large structures built same materials same manner Further Ive already performed tests sev eral own aircraft will see read Instrumentation have video cam era recorder slow playback and/or single-frame capability can learn some interesting things about airplane reacts same can done movie cameras understand what looking must know TV picture doesnt exist eyes fast enough would see thing call picture actually just spot flies back forth tracing horizontal paths TV screen takes spot 1/60th second trace other line screen lets call oddnumbered lines next 1/60th second spot traces evennumbered lines should now under stand can examine things take longer 1/30th second happen time takes construct complete TV frame display video frame drop test Continued page 157 ____________Hold 6 Release _ ______________Point Tank D Prop Horizontal Detaiis drop-test bridie simpie log decide con duct such tests means keep log examine video picture between drops make adjustments get appropriate ground con tact work up height small increments Goal such test ing determine have adequate structures safe flight August 198681 Photo TV screen taken ati35 1/30 sec Kodacoior400 after using slow motion find frame pause hold Shown Tim Myers Ouicky 500 during impact 2-ft drop about 11 ft/sec point gear totally coliapsed Re inforce landing gear considerations See text ThIs TV-screen photo example double image resulting interlace method building TV picture measuring wing tip blur knowing wing chord 18675 can estimate vertical velocity point fall However re member half blur belongs picture therefore distance traveled 1/60 sec half blur measure picture practice answer should 152 feet per second Georges Curare impact after 5-ft drop shown TVscreen photo retractable landing gear says has al ways taken much tinkering process bending back wont retract wheel wells can toil bythe bluron thetail plane already pitching back nose gear rebound Engine rework Youd better off spending time practicing racing pitting trying polish re-time soup intake restrictions new engine runs well anything else Ive seen Three-up Control Line Racing too much fun let slip away under horse power curve Quickie Rat captures excitement fun Racing does atmosphere promotes success appeals levels competitors would like hear anyone suggestions comments Frank Williams 710 Silverpines Houston TX 77062 phone 713-488-1371 Elec Champs/Naccarato Continued page 79 RC Old-Timer Seven-Cell 1 Paul Hingtgen Playboy Astro Co 05 7x800mAh Sanyo 2020 pts 2 Bob Sliff Playboy Astro Co 05 7x800mAh Sanyo 2008 pta 3 Larry Jolly Interceptor Aatro Co 05 7x800mAh Sanyo 1996 pta 4 Chuck Hollinger Nomad Astro Co 05 7x800mAh Sanyo 1865 pta 5 Jim Hall Playboy Leisure 05 7x800 mAl Sanyo 1860 pta RC Old-Timer Open 1 Mike Charles Super Quaker Aatro Co 60 26x800mAh Sanyo 2020 pta 2 Frank Chasteler Lanzo Keller 351 6x800 nAh Sanyo 2020 pta 3 Ross Thomas Lanzo Astro Co 40 26x800mAh Sanyo 2013 pta 4 Lowell Howe Sunduater Astro Co 251 6x800mAh Sanyo 1660 pta 5 Larry Jolly Interceptor Astro Co 05 7x800mAh Sanyo 1619 pta RC Stand-Off Scale 1 Bill Young Stephens Akro Aatro Co 60 3Oxl200mAh Sanyo 204 pta 2 Brian Chan Bede-5N Keller 25 l4xl200mAh Sanyo 177 pta 2 Ken Holcomb PorterfieldAatroSF 15 1 2x1 200mAh Sanyo 135 pta 3 Tony Naccarato J-3 Cub Astro Co 60 28xl200mAh Sanyo 129 pta 4 Bob Sliff Monocoupe Astro SF 40 18x l200mAh Sanyo 127 pta RC Aerobatics 1Steve Neu MKArrow Keller 50 14x1 200mAh GE 150 pta 2 Larry Jolly XC-40 Keller8O 26x1 200mAh GE 145 pta 4 Ed Depue Etude Astro 05 7x1 200mAh Sanyo 71 pta 4 Bob Sliff Snark Astro 05 7x1 200mAh Sanyo 50 pta RC Pylon Racing Seven-Cell 1 Larry Jolly Ohmen Astro Co 05 7x1 200mAh Sanyo 8 pta 2 Lowell Howe Fast Eddy Astro Co 05 7x1 200mAh Sanyo 6 pta 3 Mike Charles Avanti Keller 25 7xl200mAh GE 3 pta 4 Steve Neu original Keller 25 7xl200mAh Sanyo 3 pta Load Tests/Myers Continued page 81 frame will show two blurred images happens because TV image really made interlacing two pictures made 1/60th second apart described above Exposure time TV pic ture effectively 1/60th second movie camera can obtain similar formation double images since movie cameras make whole frame once Silent movies usually taken 18 frames per second sound movies taken 24 frames per second both exposed 1/40th second assuming using Kodachrome film Video USA always 30 frames per second interlaced described above movie camera has slow motion capability may get 36 54 frames per second shorter exposure like 1/90th 1/200th second Some home movie cam eras can synchronized strobe units light briefly 1/50000th second Short exposures can minimize blurring relative both TV image common movie camera exposure time 1/40th second Thats enough about simple instrumentation sample test drop testing airplane having performance characteristics akeady well known can accomplish two things can demonstrate method works can validate procedure convince correlation between what see test what see service preparing article made series free drops onto turf using Spickler Quicky 500 flown times built kit included stock wire landing gear videotape shows two feet drop height gear let belly fuselage hit ground plane bounced foot air hit again tail skid slammed down bounced couple times wheels Experienced Quicky 500 fliers will testify make such landing will indeed break prop After bouncing stopped landing gear rest plane looked undamaged except dents wheels went up through wing leading edge bottom sheeting same thing happened drops up five feet except belly hit harder prop turning would have broken just about drop test corresponds flight experiences Now would say landing gear passed failed drop test After repairing wing few times buying bunch props might decide stiffer landing gear would help situation course can land better wont have trouble Thus might might evaluate drop test results failure landing gear neither tore out airplane nor sep arated two loose pieces Given favorable landing conditions skillful pilot possible land Quicky 500 breaking prop Lots fliers discussion reader should also aware design aircraft model full-size mixture com promises ideal situation aspect may detrimental another Quicky 500 gear somewhat springy allows placing wheels near CG improved takeoffs opposite side coin very stiff landing gear might ripped off causing damage subjected landing condition type would make wheels dent Quicky 500 wing Regardiess evaluate landing gear would call successful proof test airplane wasnt broken testing over consider wing damage secondary dam age due flexibility landing August 1986 157 C C C U 1 I m z 0 z z C, 0 -a 0 -U m I m C- Q 0 0 -I CD U 0 0 C -00 C 0 U 0 Lij N CD 0 31 x 0 x N Plane cOnstructIOn models ghree large sheets parts shown full scale Weight down construction balsa plywood Models avaifable F 84-F Thunderatreak Sabre F 100 Super Saber SF16 Fighting Falcons F 15 Eagle Mirage 2000 21 Fishbed 71 Blackbird F 104 Start ighter Fit typee ducted fan anita wheel 5 dia 40 60 engines Available also motor ducted fan unit cunopy Price plan 5000 US dollars includes shipment air mail rolled lube Wlt free literature laformaf Ion G Bertella Via Matteotti 248 Gardone VT 25083 Brescia Italy 3W PACIFIC ACE 4 Complete kit $750 plus $150 S & H Also Rearwin Speedster Cessna 34Fairey Battle Fairchild Ranger & Lambert Monocoupe 30 Price $1000 Ea SEAGLEN MODEL CO BOX 123 Plympton MA 02367 gear results corresponded what demonstrated service would argue better find problem before decorate airplane drop testing loaded airframe perhaps could find problem two-foot drop height make proper repair continue five-foot drop height have lot better time flying plane afterward Should think springiness Quicky 500 problem flying skills instance might decide reinforcing underside wing sheeting wheels would hit hard landing would better solution substituting rigid gear Test procedures Start three-inch drop work way up table Measure drop height ground up bottom wheels time release examine videos airplane after drop actual vertical velocity contact will less given table because aerodynamic effects easier measure predict aerodynamic forces horizontal tail will rotate fuselage nose-down attitudemore like crash landingand must counteract rotation can example fasten long lightweight pole fuselage allow ing project rear Use far end pivot ground ensure plane hits ground proper flared landing attitude important thing sure weight pole isnt supported landing gear pole cant damage airplane used sixounce string arrows stabilize Minimoustang survived five-foot drops damage agrees service experience Minimoustang lightly-built pound 049-powered model Ive never trouble landing gear no matter badly plane handled arrows werent quite stiff enough control Minimoustang completed five-foot drops slightly nose-down attitude didnt get enough out line hit engine ground satisfied Another way control pitching tendency start model little nose high Use three-point suspension bridle made heavy thread get reproducible rigging angie support bridle singie loop thread will give clean release Start low drops observe results Keep increasing angie drop height increases dropped Curare retractable landing gear legs bent back enough wouldnt go wheel wellsas happens fly horizontal tail removable re place comparable weight will practically eliminate pitch changes during drop used approach droptesting Aquila usually fly over turf sol test over turf flying over pavement would carefully test over pavement Most likely would put down sheet plywood drop plane since pavement abrasive may wondering simulate effects uneven terrain rearward load tires generate landing drop-testing Navy aircraft spin wheels backward correct rpm simulate touchdown land specially-prepared steel plates also apply upward load wings simu lating lift equal 2/3 weight aircraft dont think refinements necessary RC model proof drop test Besides its pretty hard accurately simulate landing chuck hole use bridle technique set up landing angies testing full-size air craft dont use pivot arm because dont need dealing wing loadings 40 pounds per square foot RC models have loadings range half two pounds per square foot can change attitude considerably half-second takes fall five feet other hand have personally applied vertical velocities excess 35 ft/sec measurement attempting break Navy landing gear Grumman aircraft full-size airplanes begin fly So have make compen sations Have validated drop test mind Next time well take up static tests wings meantime now thinking seriously about test program new Quarter Scale model before pass ing plans around can obtain video tape drop tests sending $25 address below dont guarantee performing test others expect write about future will provide answers seems logical doing something has better doing nothing wont get professionalquality tape think its pretty good example home video tape contains additional information primarily way detail also contains visual evidence did what said did validate method George M Myers 70 Froehlich Farm Rd Hicksville NY 11801 QN/Cowley Continued page 90 square C-channel spar designed stiff spanwise bending yet remain flexible torsion Predicting exact character istics spar through analysis allowing spanwise lift distribution influenced flowing changes wing chord proved major undertaking goal develop structure would auto matically respond changing torsional loads producing appropriate wing twist distribution Lift membrane wing covering transferred spar again nature provided valuable clues Chordwise 158 Model Aviation RC SOARING DIGEST monthly publication COVCI fig International PC Soaring Scene SI 6lyearin USA US $20/yr Canada& Mexico US $24/yr elsewhere via airmail RCSD PO Box 269 Peterborough NH 03458 Far 020 Engines Free-Flight Rubber Pulse small Multi Channel R/C systems suitable 50 years ago vary capable aircraft ft well proportioned stable modal flight lotarestieg $2295 design landieg itself balsa structural techngaes KIT#102 WOce got chore 01 fauoritas Please send Finlire Caralog Ptroro 17031 2739593 DoaarsonO EIsrrihutoro ore nodal FLYLINE MODELS INC PO Bax 2136 Fairfax Virginia 22031 Full Size Plans Ducted Fans 1