CONTROL Reversal subject stability explored recent column touched treacherous situation control stick needed pushed rather pulled regain flying speed stop models descent Having manifestation phenomenon called control reversal Scale models particularly susceptible because often have low power relative weight throttle open flying full speed apply up elevator nose will rise plane will climb process repeated several times additional up elevator soon reach point nose comes up no climb because insufficient power available maintain speed up elevator control moved further nose will again rise plane will begin descend mushing condition point see effect control reversal Up elevator has caused airplane descend recover flying speed keep plane air must apply down elevator regain lift though wing completely stalled climb reduced zero gone beyond begin descent Pas sage through zone dependent upon amount up elevator available control surface movement great enough descent can quite rapid flier becomes alarmed applies up elevator stall disaster follow Gravity drag high angle attack have combined cause control reversal glide power idle same condition can precipitated identical results Knowledge phenomenon can used advantage Landing dead engine example stretch glide use slight down elevator shorten gliding distance up elevator will cause mushing rapid descent must used caution model will continue ground damaged Up elevator must relaxed gain speed before touch ing down Try altitude first acquire familiarity Keep mind turbulence wind friction over earths surface will accelerate descent near ground greatest rate climb scale models extremely nose-high atti tude large angle attack occurs rather modest angle During glide will found same angle attack airspeed used climbing will result flattest glide longest distance traveled Lifting nose elevator control will steepen glide after flattest glide condition has established demonstrating again reversal controls What really saying elevator controls speed throttle controls altitude Recognition conditions flight can prevent stalls spins can reduce model bundle sticks must kept mind conditions previously described worsened during mild turn Once wing has lowered 24 Model Aviation Finely detailed Stinson Voyager Dario Briaighella whoae beautifui airpianca have high-iighted Toiedo Show years prototype rebuiit Dario become prlzewinning Clasaic entry Oshkosh EAA convention Darlosfinishes otherworldly A1/4-scaie masterpiece spans 8 ft 7 weighs 24 pounds modified Quadra reduce vibration balancing flywheel after critical analysis time considered un-flyable Gee Bee racers have become Harold Parentis Sport Scale P-39 Bell Airacobra uses Supertigre 60 attractive subjects scaleand fly well Bob Pound weighs Balsa construction covered MonoKote trimmed K&B Epoxy 9 pounds 0980 engIne snd finished K&B Super Poxy Hal frequent winner scaie events turn part lift being employed change direction lost against gravity Because riding model exact angle nose above horizon difficult ascertain experimented phenomenon Taylorcraft became easily visible throttle closed control wheel pulled back very gradually keeping nose level flight position After minute two wheel reached its rearward stop up elevator fully applied airspeed indicator read 35 mph near stalling speed just above stall felt no buffeting T-craft falling rapidly level flight position like parachute descent continued ground would have disastrous stop descent throttle opened elevator control relaxed until return normal flight best example found model flying parachute-like descent de-thermalized free-flight plane avoid control reversal conditions SHOCK SPRING 4130 STL TUBE STRUT BODY REBOUND0 BRASS BUSHING BRASS TUBE STEEL BRACKET UPPERLOWER SCISSORS BRACKETS -STEEL 2024 ALUM SCISSORS C II II II II II II II BRASS HUB I Ii II II II II II II shockabsorbing singiestrut iandinj gear turns heavy wire needed absorb shock damage plane Spring winding art explained text useful areas must fly angles attack less instance takeoff may required maximum climb flattest obstruction such tall grass low shrubglide examples situations bery flight path nose should possible condition kept down gather speed momentary should momentary sustained Continued page 98 May1979 25 Don parsens seen ready boxatSouthwestern Championships flies Martin-Baker MB-5 both Pattern Scale events Built fac tory plans signed MartIn absolute scale Randy Randolph photo US Coast Guard Grumman MUi 6C Albatross built 1 -in scale has 96-in wing span Large projectatChicago Expodone Fred Kouka Heres easy V4scale projecta Davis DA2A Don Sobbe clean looking ship entered Sport Scale Chicago Expo paper pattern cowl skin fits properly cut skin piece 1/32 plywood Finally clamp epoxy skin place may help moisten outside skin water help conform cowl curvature After sanding fitting cowl fuselage cut holes cowl engines needle valve exhaust extension cooling air exit bottom can also cut hole cowl glow plug connector instead install jack cowl perma nently wired engine glow plug Covering Finishing model covered silk fuselage medium weight Silkspan wings tail surfaces Plastic shrink film could used wings horizontal tail surfaces weight penalty same time increase resistance punctures Before final painting add windshield window framing cut heavy paper finished airplane 3 4 coats butyrate low-shrink dope followed two coats butyrate sanding sealer After light sanding sprayed two coats color butyrate Trim stripes registration numbers masked off sprayed after door outlines various panels outlined drawing pen ink inked areas sprayed coat clear butyrate seal against fuel oil Flying Make sure model balances within position indicated plans no warps have crept flying surfaces model weighs less 2 pounds hardly thing else say first test flights should piece cake small amount right rudder may needed beginning takeoff roll Hold down runway bit down elevator necessary build up reasonable amount speed before lift off first few flights very small amount up elevator will get Waco airborne smooth straight shallow climb-out Later will able pull off after very short ground roll still have solid control 94 prop mild fuel model performs very well off grass hardsurfaced runways no quirks kind ground air 2/3 throttle its flight characteristics very smooth scale-like repeat once again believe light wing loading principal reason docile performance After several trim flights should doing spot landings touch-and-goes best Welcome Waco club happy landing RC Scale/Wischers continued page 25 increase climb angle used borrow altitude speed clear obstacle returning normal climb soon pos sible instant touch-down three-point landing tail wheel plane also exceeding attack angle flat glide During aerobatics often use high angles attack intentional maneuvers done awareness results What trying avoid condition up elevator held inadvertently unnoticed easing back stick concentrating takeoff landing approach best weapon against problem control reversal de-sensitize elevator control reducing travel approximately 15 degrees side center An expensive solution would dual-rate elevator con trol transmitter travel could limited takeoff landing elevator stick springs could tightened transmitter conscious effort needed obtain greater travel solution dislike because affinity aero batics Finally holding angle bank during turns near ground less 20 degrees will help avert trouble Lets disappoint come watch thousand-hour scale models crash flier confesses no fear accidents cannot fly planes qualification fly built-in apprehension Single Strut Landing Gears scale models best friend landing gear will absorb shock damage struc ture devise such gear best follow full-scale practice using coil com pression springs absorb both direct rebound shock Preferred material strut body thin-wall chrome molybdenum 4130 steel tube type used welded aircraft fuselage construction Scrap lengths needed usually obtainable friendly neighborhood airport fixed base operator desireable size 50 outside diameter wall thickness 035 Its retail price should about $150 per foot Other materials such brass lower grades steel can used strength does approach 4130 aircraft tubing lower leg moves vertically within strut body formed 156 music wire built up brass tube proper scale diameter brass turning made rod covers wire bend also serves mount lower scissors yoke Scissors filed solid aluminum bar preferably 2024 alloy ease machining hardness four scissors parts identical Springs wound music wire Winding forces greater can managed hand springs wound mandrel chucked lathe using back gears obtain slowest possible winding speed wind springs hand mandrel would need driven 6 8 long crank lever mandrel supported substantial bearings clamped vise mandrel should slightly smaller desired inside diameter spring because will some opening coils after winding wire-size hole drilled through mandrel secures wire starting coiling winding manually person turns crank second uses visegrip plier apply maximum tension wire Coils laid spacing will result proper free length spring desired number turns has reached Spacing between adjacent coils important winding spring length fit strut body Music wire hobby shop variety discouraged first attempts correct Most made trial error method real trick get two sufficiently similar length number turns both landing gear legs Springs 98 Model Aviation FINISH MODEL AS ANY ONE OF THREE DIFFERENT AIRCRAFT #121 GILMORE RED LION MISS PATTERSON MISS NEW ORLEANS PRICE $595 FROM YOUR DEALER OR ORDER DIRECT ADDING 15% POSTAGE AND HANDLING SRND5OFORCATALOG DEPt MA PAWNEE STREET MARCOS CALIFORNIA 9 wound too short can used adding spacers washers end wise err short direction spring has less turns other can used difference 10% maximum First last turns should wound no gap between coils 50 outside diameter strut bodies plane weighing near ten pounds likely shock spring would wound 062 diameter wire 28 din mandrel 24 turns free length fit spring space plus 25 spring has rate 225 pounds per inch deflection compressed strut its mating rebound spring preloaded 25 will support planes weight excessive deflection hard landing will compress nominal 125 deflection absorb load 28 pounds one-wheel landing 56 pounds both 5 times planes weight lower rebound springs could wound 046 diameter wire 3 1 diameter mandrel 6 turns free length fit its space plus 25 Its rate about same shock spring rebound springs omitted expect loud noises gear landing Shock rebound springs compress about equally assembly 25 heavier planes use larger wire less turns Fewer turns will stiffen spring could lead bouncy landings because higher spring rate As example 24 turns changed 18 rate pounds per inch changes 225 30 calculate loads pounds per inch deflec tion use following formula Spring rate Load 0000 d4 8 D3 N 11500000 music wire torsional modulus elasticity Small d wire diameter D s diameter spring OD minus wire din N er turns 8 constant electronic calculator its snap Multiply rate deflection get actual load spring point its travel beginning free length keeping mind spring already partially loaded assembled strut wheel alignment camber angle slight slope brings tires closer together bottom contact runway top bending axle wires camber angle dihedral angle 90 degrees added find wire bend angle Assembly sequence follows Silversolder-braze steel bracket strut body Solder brass tube hub right left axle wire Place bushing rebound spring lower leg solder other bushing top end Insert leg strut body solder lower brass bushing body making certain no solder creeps sliding fit leg Solder upper scissors bracket strut body careful alignment brazed bracket Insert shock spring solder brass stop tube upper end vent hole required stop strut will pneumatic shock absorber Assemble scissors lower bracket screws Solder lower bracket hub remove scissors tap short #256 screw lower bracket hub remove shear loads solder joint prefer use lead-tin 50-50 solder brazed steel bracket because brazing heat will damage music wire stop tube top end must very securely soldered carries considerable load compressed springs initially heavy final loads hard landing brass hexagon head screws nuts hobby shop items used model railroaders assembled Loctite prevent vibration loosening Lubricate sliding parts light oil mount struts wing should solid material such plywood main wing spar extending through center section hardwood block 50 hole bored strut epoxy glued spar Steel threaded rods go through blocks spar extending rear spar spreading load rearward shocks 156 dia music wire thick washers spacers soldered wire epoxy glued against spar husky substitute threaded rods Block rods must assembled early wing construction Most gears angle forward wheel centers forward spar single wood screw will hold strut place its socket Drawing Source George H Clapp offering 1/20th scale drawings fullsize folding-wing 1927 Fairchild FC-2 along photos scale documentation same highly detailed drawings pub lished March issue ModelAviation full-size prints original additional photos will useful prepara tion scale documentations Send 25 self addressed stamped business size envelope list George H Clapp Box 115 Central Square NY 13036 Letters Readers February column requested letters questions readers didnt expect flood correspondence followed Some highly technical little over heads average question concerned basic things bother modelers surprisingly large per centage letters other RC Scale types meaning material need addressed people alone would like personally thank took time write hope near future answer letter mail well through column Bob Dolly Wischer Rt 1 S-221 Lapham Peak Roa4 Delqfiel4 WI 53018 RC Aerobatics/Van Putte continued page 26 good enough competitive current Novice class would like compete level consistent flying ability Another opinion crops up now letters sophistication radio systems some classes should limited dual-rate switches roll-buttons impression get writers seem think radios sophistication enables flier some maneuvers doing nothing push button throw switch just case Anyone has watched busy both hands during Slow Roll maneuver can refute statement dual 100 Model Aviation
Edition: Model Aviation - 1979/05
Page Numbers: 24, 25, 98, 100
CONTROL Reversal subject stability explored recent column touched treacherous situation control stick needed pushed rather pulled regain flying speed stop models descent Having manifestation phenomenon called control reversal Scale models particularly susceptible because often have low power relative weight throttle open flying full speed apply up elevator nose will rise plane will climb process repeated several times additional up elevator soon reach point nose comes up no climb because insufficient power available maintain speed up elevator control moved further nose will again rise plane will begin descend mushing condition point see effect control reversal Up elevator has caused airplane descend recover flying speed keep plane air must apply down elevator regain lift though wing completely stalled climb reduced zero gone beyond begin descent Pas sage through zone dependent upon amount up elevator available control surface movement great enough descent can quite rapid flier becomes alarmed applies up elevator stall disaster follow Gravity drag high angle attack have combined cause control reversal glide power idle same condition can precipitated identical results Knowledge phenomenon can used advantage Landing dead engine example stretch glide use slight down elevator shorten gliding distance up elevator will cause mushing rapid descent must used caution model will continue ground damaged Up elevator must relaxed gain speed before touch ing down Try altitude first acquire familiarity Keep mind turbulence wind friction over earths surface will accelerate descent near ground greatest rate climb scale models extremely nose-high atti tude large angle attack occurs rather modest angle During glide will found same angle attack airspeed used climbing will result flattest glide longest distance traveled Lifting nose elevator control will steepen glide after flattest glide condition has established demonstrating again reversal controls What really saying elevator controls speed throttle controls altitude Recognition conditions flight can prevent stalls spins can reduce model bundle sticks must kept mind conditions previously described worsened during mild turn Once wing has lowered 24 Model Aviation Finely detailed Stinson Voyager Dario Briaighella whoae beautifui airpianca have high-iighted Toiedo Show years prototype rebuiit Dario become prlzewinning Clasaic entry Oshkosh EAA convention Darlosfinishes otherworldly A1/4-scaie masterpiece spans 8 ft 7 weighs 24 pounds modified Quadra reduce vibration balancing flywheel after critical analysis time considered un-flyable Gee Bee racers have become Harold Parentis Sport Scale P-39 Bell Airacobra uses Supertigre 60 attractive subjects scaleand fly well Bob Pound weighs Balsa construction covered MonoKote trimmed K&B Epoxy 9 pounds 0980 engIne snd finished K&B Super Poxy Hal frequent winner scaie events turn part lift being employed change direction lost against gravity Because riding model exact angle nose above horizon difficult ascertain experimented phenomenon Taylorcraft became easily visible throttle closed control wheel pulled back very gradually keeping nose level flight position After minute two wheel reached its rearward stop up elevator fully applied airspeed indicator read 35 mph near stalling speed just above stall felt no buffeting T-craft falling rapidly level flight position like parachute descent continued ground would have disastrous stop descent throttle opened elevator control relaxed until return normal flight best example found model flying parachute-like descent de-thermalized free-flight plane avoid control reversal conditions SHOCK SPRING 4130 STL TUBE STRUT BODY REBOUND0 BRASS BUSHING BRASS TUBE STEEL BRACKET UPPERLOWER SCISSORS BRACKETS -STEEL 2024 ALUM SCISSORS C II II II II II II II BRASS HUB I Ii II II II II II II shockabsorbing singiestrut iandinj gear turns heavy wire needed absorb shock damage plane Spring winding art explained text useful areas must fly angles attack less instance takeoff may required maximum climb flattest obstruction such tall grass low shrubglide examples situations bery flight path nose should possible condition kept down gather speed momentary should momentary sustained Continued page 98 May1979 25 Don parsens seen ready boxatSouthwestern Championships flies Martin-Baker MB-5 both Pattern Scale events Built fac tory plans signed MartIn absolute scale Randy Randolph photo US Coast Guard Grumman MUi 6C Albatross built 1 -in scale has 96-in wing span Large projectatChicago Expodone Fred Kouka Heres easy V4scale projecta Davis DA2A Don Sobbe clean looking ship entered Sport Scale Chicago Expo paper pattern cowl skin fits properly cut skin piece 1/32 plywood Finally clamp epoxy skin place may help moisten outside skin water help conform cowl curvature After sanding fitting cowl fuselage cut holes cowl engines needle valve exhaust extension cooling air exit bottom can also cut hole cowl glow plug connector instead install jack cowl perma nently wired engine glow plug Covering Finishing model covered silk fuselage medium weight Silkspan wings tail surfaces Plastic shrink film could used wings horizontal tail surfaces weight penalty same time increase resistance punctures Before final painting add windshield window framing cut heavy paper finished airplane 3 4 coats butyrate low-shrink dope followed two coats butyrate sanding sealer After light sanding sprayed two coats color butyrate Trim stripes registration numbers masked off sprayed after door outlines various panels outlined drawing pen ink inked areas sprayed coat clear butyrate seal against fuel oil Flying Make sure model balances within position indicated plans no warps have crept flying surfaces model weighs less 2 pounds hardly thing else say first test flights should piece cake small amount right rudder may needed beginning takeoff roll Hold down runway bit down elevator necessary build up reasonable amount speed before lift off first few flights very small amount up elevator will get Waco airborne smooth straight shallow climb-out Later will able pull off after very short ground roll still have solid control 94 prop mild fuel model performs very well off grass hardsurfaced runways no quirks kind ground air 2/3 throttle its flight characteristics very smooth scale-like repeat once again believe light wing loading principal reason docile performance After several trim flights should doing spot landings touch-and-goes best Welcome Waco club happy landing RC Scale/Wischers continued page 25 increase climb angle used borrow altitude speed clear obstacle returning normal climb soon pos sible instant touch-down three-point landing tail wheel plane also exceeding attack angle flat glide During aerobatics often use high angles attack intentional maneuvers done awareness results What trying avoid condition up elevator held inadvertently unnoticed easing back stick concentrating takeoff landing approach best weapon against problem control reversal de-sensitize elevator control reducing travel approximately 15 degrees side center An expensive solution would dual-rate elevator con trol transmitter travel could limited takeoff landing elevator stick springs could tightened transmitter conscious effort needed obtain greater travel solution dislike because affinity aero batics Finally holding angle bank during turns near ground less 20 degrees will help avert trouble Lets disappoint come watch thousand-hour scale models crash flier confesses no fear accidents cannot fly planes qualification fly built-in apprehension Single Strut Landing Gears scale models best friend landing gear will absorb shock damage struc ture devise such gear best follow full-scale practice using coil com pression springs absorb both direct rebound shock Preferred material strut body thin-wall chrome molybdenum 4130 steel tube type used welded aircraft fuselage construction Scrap lengths needed usually obtainable friendly neighborhood airport fixed base operator desireable size 50 outside diameter wall thickness 035 Its retail price should about $150 per foot Other materials such brass lower grades steel can used strength does approach 4130 aircraft tubing lower leg moves vertically within strut body formed 156 music wire built up brass tube proper scale diameter brass turning made rod covers wire bend also serves mount lower scissors yoke Scissors filed solid aluminum bar preferably 2024 alloy ease machining hardness four scissors parts identical Springs wound music wire Winding forces greater can managed hand springs wound mandrel chucked lathe using back gears obtain slowest possible winding speed wind springs hand mandrel would need driven 6 8 long crank lever mandrel supported substantial bearings clamped vise mandrel should slightly smaller desired inside diameter spring because will some opening coils after winding wire-size hole drilled through mandrel secures wire starting coiling winding manually person turns crank second uses visegrip plier apply maximum tension wire Coils laid spacing will result proper free length spring desired number turns has reached Spacing between adjacent coils important winding spring length fit strut body Music wire hobby shop variety discouraged first attempts correct Most made trial error method real trick get two sufficiently similar length number turns both landing gear legs Springs 98 Model Aviation FINISH MODEL AS ANY ONE OF THREE DIFFERENT AIRCRAFT #121 GILMORE RED LION MISS PATTERSON MISS NEW ORLEANS PRICE $595 FROM YOUR DEALER OR ORDER DIRECT ADDING 15% POSTAGE AND HANDLING SRND5OFORCATALOG DEPt MA PAWNEE STREET MARCOS CALIFORNIA 9 wound too short can used adding spacers washers end wise err short direction spring has less turns other can used difference 10% maximum First last turns should wound no gap between coils 50 outside diameter strut bodies plane weighing near ten pounds likely shock spring would wound 062 diameter wire 28 din mandrel 24 turns free length fit spring space plus 25 spring has rate 225 pounds per inch deflection compressed strut its mating rebound spring preloaded 25 will support planes weight excessive deflection hard landing will compress nominal 125 deflection absorb load 28 pounds one-wheel landing 56 pounds both 5 times planes weight lower rebound springs could wound 046 diameter wire 3 1 diameter mandrel 6 turns free length fit its space plus 25 Its rate about same shock spring rebound springs omitted expect loud noises gear landing Shock rebound springs compress about equally assembly 25 heavier planes use larger wire less turns Fewer turns will stiffen spring could lead bouncy landings because higher spring rate As example 24 turns changed 18 rate pounds per inch changes 225 30 calculate loads pounds per inch deflec tion use following formula Spring rate Load 0000 d4 8 D3 N 11500000 music wire torsional modulus elasticity Small d wire diameter D s diameter spring OD minus wire din N er turns 8 constant electronic calculator its snap Multiply rate deflection get actual load spring point its travel beginning free length keeping mind spring already partially loaded assembled strut wheel alignment camber angle slight slope brings tires closer together bottom contact runway top bending axle wires camber angle dihedral angle 90 degrees added find wire bend angle Assembly sequence follows Silversolder-braze steel bracket strut body Solder brass tube hub right left axle wire Place bushing rebound spring lower leg solder other bushing top end Insert leg strut body solder lower brass bushing body making certain no solder creeps sliding fit leg Solder upper scissors bracket strut body careful alignment brazed bracket Insert shock spring solder brass stop tube upper end vent hole required stop strut will pneumatic shock absorber Assemble scissors lower bracket screws Solder lower bracket hub remove scissors tap short #256 screw lower bracket hub remove shear loads solder joint prefer use lead-tin 50-50 solder brazed steel bracket because brazing heat will damage music wire stop tube top end must very securely soldered carries considerable load compressed springs initially heavy final loads hard landing brass hexagon head screws nuts hobby shop items used model railroaders assembled Loctite prevent vibration loosening Lubricate sliding parts light oil mount struts wing should solid material such plywood main wing spar extending through center section hardwood block 50 hole bored strut epoxy glued spar Steel threaded rods go through blocks spar extending rear spar spreading load rearward shocks 156 dia music wire thick washers spacers soldered wire epoxy glued against spar husky substitute threaded rods Block rods must assembled early wing construction Most gears angle forward wheel centers forward spar single wood screw will hold strut place its socket Drawing Source George H Clapp offering 1/20th scale drawings fullsize folding-wing 1927 Fairchild FC-2 along photos scale documentation same highly detailed drawings pub lished March issue ModelAviation full-size prints original additional photos will useful prepara tion scale documentations Send 25 self addressed stamped business size envelope list George H Clapp Box 115 Central Square NY 13036 Letters Readers February column requested letters questions readers didnt expect flood correspondence followed Some highly technical little over heads average question concerned basic things bother modelers surprisingly large per centage letters other RC Scale types meaning material need addressed people alone would like personally thank took time write hope near future answer letter mail well through column Bob Dolly Wischer Rt 1 S-221 Lapham Peak Roa4 Delqfiel4 WI 53018 RC Aerobatics/Van Putte continued page 26 good enough competitive current Novice class would like compete level consistent flying ability Another opinion crops up now letters sophistication radio systems some classes should limited dual-rate switches roll-buttons impression get writers seem think radios sophistication enables flier some maneuvers doing nothing push button throw switch just case Anyone has watched busy both hands during Slow Roll maneuver can refute statement dual 100 Model Aviation
Edition: Model Aviation - 1979/05
Page Numbers: 24, 25, 98, 100
CONTROL Reversal subject stability explored recent column touched treacherous situation control stick needed pushed rather pulled regain flying speed stop models descent Having manifestation phenomenon called control reversal Scale models particularly susceptible because often have low power relative weight throttle open flying full speed apply up elevator nose will rise plane will climb process repeated several times additional up elevator soon reach point nose comes up no climb because insufficient power available maintain speed up elevator control moved further nose will again rise plane will begin descend mushing condition point see effect control reversal Up elevator has caused airplane descend recover flying speed keep plane air must apply down elevator regain lift though wing completely stalled climb reduced zero gone beyond begin descent Pas sage through zone dependent upon amount up elevator available control surface movement great enough descent can quite rapid flier becomes alarmed applies up elevator stall disaster follow Gravity drag high angle attack have combined cause control reversal glide power idle same condition can precipitated identical results Knowledge phenomenon can used advantage Landing dead engine example stretch glide use slight down elevator shorten gliding distance up elevator will cause mushing rapid descent must used caution model will continue ground damaged Up elevator must relaxed gain speed before touch ing down Try altitude first acquire familiarity Keep mind turbulence wind friction over earths surface will accelerate descent near ground greatest rate climb scale models extremely nose-high atti tude large angle attack occurs rather modest angle During glide will found same angle attack airspeed used climbing will result flattest glide longest distance traveled Lifting nose elevator control will steepen glide after flattest glide condition has established demonstrating again reversal controls What really saying elevator controls speed throttle controls altitude Recognition conditions flight can prevent stalls spins can reduce model bundle sticks must kept mind conditions previously described worsened during mild turn Once wing has lowered 24 Model Aviation Finely detailed Stinson Voyager Dario Briaighella whoae beautifui airpianca have high-iighted Toiedo Show years prototype rebuiit Dario become prlzewinning Clasaic entry Oshkosh EAA convention Darlosfinishes otherworldly A1/4-scaie masterpiece spans 8 ft 7 weighs 24 pounds modified Quadra reduce vibration balancing flywheel after critical analysis time considered un-flyable Gee Bee racers have become Harold Parentis Sport Scale P-39 Bell Airacobra uses Supertigre 60 attractive subjects scaleand fly well Bob Pound weighs Balsa construction covered MonoKote trimmed K&B Epoxy 9 pounds 0980 engIne snd finished K&B Super Poxy Hal frequent winner scaie events turn part lift being employed change direction lost against gravity Because riding model exact angle nose above horizon difficult ascertain experimented phenomenon Taylorcraft became easily visible throttle closed control wheel pulled back very gradually keeping nose level flight position After minute two wheel reached its rearward stop up elevator fully applied airspeed indicator read 35 mph near stalling speed just above stall felt no buffeting T-craft falling rapidly level flight position like parachute descent continued ground would have disastrous stop descent throttle opened elevator control relaxed until return normal flight best example found model flying parachute-like descent de-thermalized free-flight plane avoid control reversal conditions SHOCK SPRING 4130 STL TUBE STRUT BODY REBOUND0 BRASS BUSHING BRASS TUBE STEEL BRACKET UPPERLOWER SCISSORS BRACKETS -STEEL 2024 ALUM SCISSORS C II II II II II II II BRASS HUB I Ii II II II II II II shockabsorbing singiestrut iandinj gear turns heavy wire needed absorb shock damage plane Spring winding art explained text useful areas must fly angles attack less instance takeoff may required maximum climb flattest obstruction such tall grass low shrubglide examples situations bery flight path nose should possible condition kept down gather speed momentary should momentary sustained Continued page 98 May1979 25 Don parsens seen ready boxatSouthwestern Championships flies Martin-Baker MB-5 both Pattern Scale events Built fac tory plans signed MartIn absolute scale Randy Randolph photo US Coast Guard Grumman MUi 6C Albatross built 1 -in scale has 96-in wing span Large projectatChicago Expodone Fred Kouka Heres easy V4scale projecta Davis DA2A Don Sobbe clean looking ship entered Sport Scale Chicago Expo paper pattern cowl skin fits properly cut skin piece 1/32 plywood Finally clamp epoxy skin place may help moisten outside skin water help conform cowl curvature After sanding fitting cowl fuselage cut holes cowl engines needle valve exhaust extension cooling air exit bottom can also cut hole cowl glow plug connector instead install jack cowl perma nently wired engine glow plug Covering Finishing model covered silk fuselage medium weight Silkspan wings tail surfaces Plastic shrink film could used wings horizontal tail surfaces weight penalty same time increase resistance punctures Before final painting add windshield window framing cut heavy paper finished airplane 3 4 coats butyrate low-shrink dope followed two coats butyrate sanding sealer After light sanding sprayed two coats color butyrate Trim stripes registration numbers masked off sprayed after door outlines various panels outlined drawing pen ink inked areas sprayed coat clear butyrate seal against fuel oil Flying Make sure model balances within position indicated plans no warps have crept flying surfaces model weighs less 2 pounds hardly thing else say first test flights should piece cake small amount right rudder may needed beginning takeoff roll Hold down runway bit down elevator necessary build up reasonable amount speed before lift off first few flights very small amount up elevator will get Waco airborne smooth straight shallow climb-out Later will able pull off after very short ground roll still have solid control 94 prop mild fuel model performs very well off grass hardsurfaced runways no quirks kind ground air 2/3 throttle its flight characteristics very smooth scale-like repeat once again believe light wing loading principal reason docile performance After several trim flights should doing spot landings touch-and-goes best Welcome Waco club happy landing RC Scale/Wischers continued page 25 increase climb angle used borrow altitude speed clear obstacle returning normal climb soon pos sible instant touch-down three-point landing tail wheel plane also exceeding attack angle flat glide During aerobatics often use high angles attack intentional maneuvers done awareness results What trying avoid condition up elevator held inadvertently unnoticed easing back stick concentrating takeoff landing approach best weapon against problem control reversal de-sensitize elevator control reducing travel approximately 15 degrees side center An expensive solution would dual-rate elevator con trol transmitter travel could limited takeoff landing elevator stick springs could tightened transmitter conscious effort needed obtain greater travel solution dislike because affinity aero batics Finally holding angle bank during turns near ground less 20 degrees will help avert trouble Lets disappoint come watch thousand-hour scale models crash flier confesses no fear accidents cannot fly planes qualification fly built-in apprehension Single Strut Landing Gears scale models best friend landing gear will absorb shock damage struc ture devise such gear best follow full-scale practice using coil com pression springs absorb both direct rebound shock Preferred material strut body thin-wall chrome molybdenum 4130 steel tube type used welded aircraft fuselage construction Scrap lengths needed usually obtainable friendly neighborhood airport fixed base operator desireable size 50 outside diameter wall thickness 035 Its retail price should about $150 per foot Other materials such brass lower grades steel can used strength does approach 4130 aircraft tubing lower leg moves vertically within strut body formed 156 music wire built up brass tube proper scale diameter brass turning made rod covers wire bend also serves mount lower scissors yoke Scissors filed solid aluminum bar preferably 2024 alloy ease machining hardness four scissors parts identical Springs wound music wire Winding forces greater can managed hand springs wound mandrel chucked lathe using back gears obtain slowest possible winding speed wind springs hand mandrel would need driven 6 8 long crank lever mandrel supported substantial bearings clamped vise mandrel should slightly smaller desired inside diameter spring because will some opening coils after winding wire-size hole drilled through mandrel secures wire starting coiling winding manually person turns crank second uses visegrip plier apply maximum tension wire Coils laid spacing will result proper free length spring desired number turns has reached Spacing between adjacent coils important winding spring length fit strut body Music wire hobby shop variety discouraged first attempts correct Most made trial error method real trick get two sufficiently similar length number turns both landing gear legs Springs 98 Model Aviation FINISH MODEL AS ANY ONE OF THREE DIFFERENT AIRCRAFT #121 GILMORE RED LION MISS PATTERSON MISS NEW ORLEANS PRICE $595 FROM YOUR DEALER OR ORDER DIRECT ADDING 15% POSTAGE AND HANDLING SRND5OFORCATALOG DEPt MA PAWNEE STREET MARCOS CALIFORNIA 9 wound too short can used adding spacers washers end wise err short direction spring has less turns other can used difference 10% maximum First last turns should wound no gap between coils 50 outside diameter strut bodies plane weighing near ten pounds likely shock spring would wound 062 diameter wire 28 din mandrel 24 turns free length fit spring space plus 25 spring has rate 225 pounds per inch deflection compressed strut its mating rebound spring preloaded 25 will support planes weight excessive deflection hard landing will compress nominal 125 deflection absorb load 28 pounds one-wheel landing 56 pounds both 5 times planes weight lower rebound springs could wound 046 diameter wire 3 1 diameter mandrel 6 turns free length fit its space plus 25 Its rate about same shock spring rebound springs omitted expect loud noises gear landing Shock rebound springs compress about equally assembly 25 heavier planes use larger wire less turns Fewer turns will stiffen spring could lead bouncy landings because higher spring rate As example 24 turns changed 18 rate pounds per inch changes 225 30 calculate loads pounds per inch deflec tion use following formula Spring rate Load 0000 d4 8 D3 N 11500000 music wire torsional modulus elasticity Small d wire diameter D s diameter spring OD minus wire din N er turns 8 constant electronic calculator its snap Multiply rate deflection get actual load spring point its travel beginning free length keeping mind spring already partially loaded assembled strut wheel alignment camber angle slight slope brings tires closer together bottom contact runway top bending axle wires camber angle dihedral angle 90 degrees added find wire bend angle Assembly sequence follows Silversolder-braze steel bracket strut body Solder brass tube hub right left axle wire Place bushing rebound spring lower leg solder other bushing top end Insert leg strut body solder lower brass bushing body making certain no solder creeps sliding fit leg Solder upper scissors bracket strut body careful alignment brazed bracket Insert shock spring solder brass stop tube upper end vent hole required stop strut will pneumatic shock absorber Assemble scissors lower bracket screws Solder lower bracket hub remove scissors tap short #256 screw lower bracket hub remove shear loads solder joint prefer use lead-tin 50-50 solder brazed steel bracket because brazing heat will damage music wire stop tube top end must very securely soldered carries considerable load compressed springs initially heavy final loads hard landing brass hexagon head screws nuts hobby shop items used model railroaders assembled Loctite prevent vibration loosening Lubricate sliding parts light oil mount struts wing should solid material such plywood main wing spar extending through center section hardwood block 50 hole bored strut epoxy glued spar Steel threaded rods go through blocks spar extending rear spar spreading load rearward shocks 156 dia music wire thick washers spacers soldered wire epoxy glued against spar husky substitute threaded rods Block rods must assembled early wing construction Most gears angle forward wheel centers forward spar single wood screw will hold strut place its socket Drawing Source George H Clapp offering 1/20th scale drawings fullsize folding-wing 1927 Fairchild FC-2 along photos scale documentation same highly detailed drawings pub lished March issue ModelAviation full-size prints original additional photos will useful prepara tion scale documentations Send 25 self addressed stamped business size envelope list George H Clapp Box 115 Central Square NY 13036 Letters Readers February column requested letters questions readers didnt expect flood correspondence followed Some highly technical little over heads average question concerned basic things bother modelers surprisingly large per centage letters other RC Scale types meaning material need addressed people alone would like personally thank took time write hope near future answer letter mail well through column Bob Dolly Wischer Rt 1 S-221 Lapham Peak Roa4 Delqfiel4 WI 53018 RC Aerobatics/Van Putte continued page 26 good enough competitive current Novice class would like compete level consistent flying ability Another opinion crops up now letters sophistication radio systems some classes should limited dual-rate switches roll-buttons impression get writers seem think radios sophistication enables flier some maneuvers doing nothing push button throw switch just case Anyone has watched busy both hands during Slow Roll maneuver can refute statement dual 100 Model Aviation
Edition: Model Aviation - 1979/05
Page Numbers: 24, 25, 98, 100
CONTROL Reversal subject stability explored recent column touched treacherous situation control stick needed pushed rather pulled regain flying speed stop models descent Having manifestation phenomenon called control reversal Scale models particularly susceptible because often have low power relative weight throttle open flying full speed apply up elevator nose will rise plane will climb process repeated several times additional up elevator soon reach point nose comes up no climb because insufficient power available maintain speed up elevator control moved further nose will again rise plane will begin descend mushing condition point see effect control reversal Up elevator has caused airplane descend recover flying speed keep plane air must apply down elevator regain lift though wing completely stalled climb reduced zero gone beyond begin descent Pas sage through zone dependent upon amount up elevator available control surface movement great enough descent can quite rapid flier becomes alarmed applies up elevator stall disaster follow Gravity drag high angle attack have combined cause control reversal glide power idle same condition can precipitated identical results Knowledge phenomenon can used advantage Landing dead engine example stretch glide use slight down elevator shorten gliding distance up elevator will cause mushing rapid descent must used caution model will continue ground damaged Up elevator must relaxed gain speed before touch ing down Try altitude first acquire familiarity Keep mind turbulence wind friction over earths surface will accelerate descent near ground greatest rate climb scale models extremely nose-high atti tude large angle attack occurs rather modest angle During glide will found same angle attack airspeed used climbing will result flattest glide longest distance traveled Lifting nose elevator control will steepen glide after flattest glide condition has established demonstrating again reversal controls What really saying elevator controls speed throttle controls altitude Recognition conditions flight can prevent stalls spins can reduce model bundle sticks must kept mind conditions previously described worsened during mild turn Once wing has lowered 24 Model Aviation Finely detailed Stinson Voyager Dario Briaighella whoae beautifui airpianca have high-iighted Toiedo Show years prototype rebuiit Dario become prlzewinning Clasaic entry Oshkosh EAA convention Darlosfinishes otherworldly A1/4-scaie masterpiece spans 8 ft 7 weighs 24 pounds modified Quadra reduce vibration balancing flywheel after critical analysis time considered un-flyable Gee Bee racers have become Harold Parentis Sport Scale P-39 Bell Airacobra uses Supertigre 60 attractive subjects scaleand fly well Bob Pound weighs Balsa construction covered MonoKote trimmed K&B Epoxy 9 pounds 0980 engIne snd finished K&B Super Poxy Hal frequent winner scaie events turn part lift being employed change direction lost against gravity Because riding model exact angle nose above horizon difficult ascertain experimented phenomenon Taylorcraft became easily visible throttle closed control wheel pulled back very gradually keeping nose level flight position After minute two wheel reached its rearward stop up elevator fully applied airspeed indicator read 35 mph near stalling speed just above stall felt no buffeting T-craft falling rapidly level flight position like parachute descent continued ground would have disastrous stop descent throttle opened elevator control relaxed until return normal flight best example found model flying parachute-like descent de-thermalized free-flight plane avoid control reversal conditions SHOCK SPRING 4130 STL TUBE STRUT BODY REBOUND0 BRASS BUSHING BRASS TUBE STEEL BRACKET UPPERLOWER SCISSORS BRACKETS -STEEL 2024 ALUM SCISSORS C II II II II II II II BRASS HUB I Ii II II II II II II shockabsorbing singiestrut iandinj gear turns heavy wire needed absorb shock damage plane Spring winding art explained text useful areas must fly angles attack less instance takeoff may required maximum climb flattest obstruction such tall grass low shrubglide examples situations bery flight path nose should possible condition kept down gather speed momentary should momentary sustained Continued page 98 May1979 25 Don parsens seen ready boxatSouthwestern Championships flies Martin-Baker MB-5 both Pattern Scale events Built fac tory plans signed MartIn absolute scale Randy Randolph photo US Coast Guard Grumman MUi 6C Albatross built 1 -in scale has 96-in wing span Large projectatChicago Expodone Fred Kouka Heres easy V4scale projecta Davis DA2A Don Sobbe clean looking ship entered Sport Scale Chicago Expo paper pattern cowl skin fits properly cut skin piece 1/32 plywood Finally clamp epoxy skin place may help moisten outside skin water help conform cowl curvature After sanding fitting cowl fuselage cut holes cowl engines needle valve exhaust extension cooling air exit bottom can also cut hole cowl glow plug connector instead install jack cowl perma nently wired engine glow plug Covering Finishing model covered silk fuselage medium weight Silkspan wings tail surfaces Plastic shrink film could used wings horizontal tail surfaces weight penalty same time increase resistance punctures Before final painting add windshield window framing cut heavy paper finished airplane 3 4 coats butyrate low-shrink dope followed two coats butyrate sanding sealer After light sanding sprayed two coats color butyrate Trim stripes registration numbers masked off sprayed after door outlines various panels outlined drawing pen ink inked areas sprayed coat clear butyrate seal against fuel oil Flying Make sure model balances within position indicated plans no warps have crept flying surfaces model weighs less 2 pounds hardly thing else say first test flights should piece cake small amount right rudder may needed beginning takeoff roll Hold down runway bit down elevator necessary build up reasonable amount speed before lift off first few flights very small amount up elevator will get Waco airborne smooth straight shallow climb-out Later will able pull off after very short ground roll still have solid control 94 prop mild fuel model performs very well off grass hardsurfaced runways no quirks kind ground air 2/3 throttle its flight characteristics very smooth scale-like repeat once again believe light wing loading principal reason docile performance After several trim flights should doing spot landings touch-and-goes best Welcome Waco club happy landing RC Scale/Wischers continued page 25 increase climb angle used borrow altitude speed clear obstacle returning normal climb soon pos sible instant touch-down three-point landing tail wheel plane also exceeding attack angle flat glide During aerobatics often use high angles attack intentional maneuvers done awareness results What trying avoid condition up elevator held inadvertently unnoticed easing back stick concentrating takeoff landing approach best weapon against problem control reversal de-sensitize elevator control reducing travel approximately 15 degrees side center An expensive solution would dual-rate elevator con trol transmitter travel could limited takeoff landing elevator stick springs could tightened transmitter conscious effort needed obtain greater travel solution dislike because affinity aero batics Finally holding angle bank during turns near ground less 20 degrees will help avert trouble Lets disappoint come watch thousand-hour scale models crash flier confesses no fear accidents cannot fly planes qualification fly built-in apprehension Single Strut Landing Gears scale models best friend landing gear will absorb shock damage struc ture devise such gear best follow full-scale practice using coil com pression springs absorb both direct rebound shock Preferred material strut body thin-wall chrome molybdenum 4130 steel tube type used welded aircraft fuselage construction Scrap lengths needed usually obtainable friendly neighborhood airport fixed base operator desireable size 50 outside diameter wall thickness 035 Its retail price should about $150 per foot Other materials such brass lower grades steel can used strength does approach 4130 aircraft tubing lower leg moves vertically within strut body formed 156 music wire built up brass tube proper scale diameter brass turning made rod covers wire bend also serves mount lower scissors yoke Scissors filed solid aluminum bar preferably 2024 alloy ease machining hardness four scissors parts identical Springs wound music wire Winding forces greater can managed hand springs wound mandrel chucked lathe using back gears obtain slowest possible winding speed wind springs hand mandrel would need driven 6 8 long crank lever mandrel supported substantial bearings clamped vise mandrel should slightly smaller desired inside diameter spring because will some opening coils after winding wire-size hole drilled through mandrel secures wire starting coiling winding manually person turns crank second uses visegrip plier apply maximum tension wire Coils laid spacing will result proper free length spring desired number turns has reached Spacing between adjacent coils important winding spring length fit strut body Music wire hobby shop variety discouraged first attempts correct Most made trial error method real trick get two sufficiently similar length number turns both landing gear legs Springs 98 Model Aviation FINISH MODEL AS ANY ONE OF THREE DIFFERENT AIRCRAFT #121 GILMORE RED LION MISS PATTERSON MISS NEW ORLEANS PRICE $595 FROM YOUR DEALER OR ORDER DIRECT ADDING 15% POSTAGE AND HANDLING SRND5OFORCATALOG DEPt MA PAWNEE STREET MARCOS CALIFORNIA 9 wound too short can used adding spacers washers end wise err short direction spring has less turns other can used difference 10% maximum First last turns should wound no gap between coils 50 outside diameter strut bodies plane weighing near ten pounds likely shock spring would wound 062 diameter wire 28 din mandrel 24 turns free length fit spring space plus 25 spring has rate 225 pounds per inch deflection compressed strut its mating rebound spring preloaded 25 will support planes weight excessive deflection hard landing will compress nominal 125 deflection absorb load 28 pounds one-wheel landing 56 pounds both 5 times planes weight lower rebound springs could wound 046 diameter wire 3 1 diameter mandrel 6 turns free length fit its space plus 25 Its rate about same shock spring rebound springs omitted expect loud noises gear landing Shock rebound springs compress about equally assembly 25 heavier planes use larger wire less turns Fewer turns will stiffen spring could lead bouncy landings because higher spring rate As example 24 turns changed 18 rate pounds per inch changes 225 30 calculate loads pounds per inch deflec tion use following formula Spring rate Load 0000 d4 8 D3 N 11500000 music wire torsional modulus elasticity Small d wire diameter D s diameter spring OD minus wire din N er turns 8 constant electronic calculator its snap Multiply rate deflection get actual load spring point its travel beginning free length keeping mind spring already partially loaded assembled strut wheel alignment camber angle slight slope brings tires closer together bottom contact runway top bending axle wires camber angle dihedral angle 90 degrees added find wire bend angle Assembly sequence follows Silversolder-braze steel bracket strut body Solder brass tube hub right left axle wire Place bushing rebound spring lower leg solder other bushing top end Insert leg strut body solder lower brass bushing body making certain no solder creeps sliding fit leg Solder upper scissors bracket strut body careful alignment brazed bracket Insert shock spring solder brass stop tube upper end vent hole required stop strut will pneumatic shock absorber Assemble scissors lower bracket screws Solder lower bracket hub remove scissors tap short #256 screw lower bracket hub remove shear loads solder joint prefer use lead-tin 50-50 solder brazed steel bracket because brazing heat will damage music wire stop tube top end must very securely soldered carries considerable load compressed springs initially heavy final loads hard landing brass hexagon head screws nuts hobby shop items used model railroaders assembled Loctite prevent vibration loosening Lubricate sliding parts light oil mount struts wing should solid material such plywood main wing spar extending through center section hardwood block 50 hole bored strut epoxy glued spar Steel threaded rods go through blocks spar extending rear spar spreading load rearward shocks 156 dia music wire thick washers spacers soldered wire epoxy glued against spar husky substitute threaded rods Block rods must assembled early wing construction Most gears angle forward wheel centers forward spar single wood screw will hold strut place its socket Drawing Source George H Clapp offering 1/20th scale drawings fullsize folding-wing 1927 Fairchild FC-2 along photos scale documentation same highly detailed drawings pub lished March issue ModelAviation full-size prints original additional photos will useful prepara tion scale documentations Send 25 self addressed stamped business size envelope list George H Clapp Box 115 Central Square NY 13036 Letters Readers February column requested letters questions readers didnt expect flood correspondence followed Some highly technical little over heads average question concerned basic things bother modelers surprisingly large per centage letters other RC Scale types meaning material need addressed people alone would like personally thank took time write hope near future answer letter mail well through column Bob Dolly Wischer Rt 1 S-221 Lapham Peak Roa4 Delqfiel4 WI 53018 RC Aerobatics/Van Putte continued page 26 good enough competitive current Novice class would like compete level consistent flying ability Another opinion crops up now letters sophistication radio systems some classes should limited dual-rate switches roll-buttons impression get writers seem think radios sophistication enables flier some maneuvers doing nothing push button throw switch just case Anyone has watched busy both hands during Slow Roll maneuver can refute statement dual 100 Model Aviation