Minor cuanges iusciag outline shape tail wing tips can change just about anything long moments areas retained Although models resembled prototypes earlier versions sometimes failed receive ten scale points under current rules scale fidelity F6F has challenged both high-and low-speed performance has satisfying Twominute low times consistently achieved realistic flight attitude official high speed 918 mph has recorded stock Tigre 1980 rules will clearly give scale spcn greater part war aviation cadet finally having first solo V-i Day fantasized lot about flying carriers never actually did fulfill boyhood dream vicariously now models reason training rushed completion success Grumman F6F Hellcat F4F Wildcat used exten sively early war US Navy Zero called Zeke faster maneuverable F6F changed course history outperforming Zero Altogether 12275 F6Fs built official records carrier deck An additional bonus awarded model closely resembles Navy carrier aircraft conflicting requirements constitute essence design challenge personally prefer Profile over Classes land II reason can design model instead simply select Although scoring system changed few years ago reduce emphasis high speed design philosophy remained same Design best high speed add refinements enhance low speed provided high-speed capability significantly affected 40 Model Aviation article will attempt show what also design Contrary popular notions drag necessarily minimized using short stubby wing higher aspect ratio wing has higher lift its easier fly both high low speeds Take look speed plane next meet rat racer Youll find winners have aspect ratios around 6 1 has Reynolds Number airspeed boundary layer separation chord greater about nine inches will start experience sharp increase parasitic drag above 90 mph wing area 300 sq span should 424 mean chord should 71 taper about 100 makes wing look enough better constant-chord wing justify little extra work certainly doesnt impair performance probably helps little rate establishes root chord 9 tip chord 525 early planes configuration adjustable leadout guides impressed difference high speed control low speed changes leadout placement already decided make next controllable heard someone else doing considerable success next version slightly shorter span accommo date greater tip chord leadouts could move farther have pronounced effect low speed Next considered wing design airfoil shape good general-purpose airfoil thickness 15% chord again borrow ing established speed technology chose 10% Back during Depression number people found employment tedious particularly useful government-sponsored program deriving empirical equations different airfoil shapes using slide rules mechanical calculators set about wind tunnels determine performance characteristics flaps various configurations NACA 4-digit series thickness camber extent location varied around basic streamline shape NACA 2410 airfoil used has 2% camber first digit centered 40% aft leading edge second digit has maximum thickness 10% chord last two digits centerline really two parabolas meet 2% up 40% aft basic streamline shape 10% thick wrapped around makes lower surface just about flat used formidable fifth-order equation exercise programming modern computer use work ultimately succeeded getting computer plot airfoil exact scales required elected use somewhat thinner symmetrical airfoil tip NACA 0007 provides slightly tapered wing just little washout tip common speed models tip chamfered bottom surface give currently popular shape said minimize tip vortices ribs undercut allow cap strips gives truer airfoil surface adds strength much added weight TBF models split flaps because prototype did used conventional flaps F6F NACA curves show 300 movement yields maximum lift set 450 because best low-speed performance some additional drag desirable expense lift Maintaining line tension low speed essential ways achieve simplest add tip weight added weight reduces acceleration critical first lap off deck high speed will authortook first Profile Carrier second B Proto Speed fourth Jet Speed atthe 1979 Nats Two-minute low times consistently achieved Hellcat realistic flight attitude official 918 mph high has recorded stock Tigre noticeably slower added weight plane flies very well no tip weight Ailerons make plane tend bank right extreme up elevator used low speed tends cause right turn rudder also moves right upon hook deployment Only right aileron made move induces differential drag introduces yaw right actions serve maintain line tension low speed release mechanism use little bit unusual tried design system latched high speed position driven low speed positions stored energy throttle leadout rigid 0032 wire has bent piece wire carefully soldered usual fine copper wire binding must posi tioned perfectly high speed wire pins brass line slider forward position slotted fiberglass tip rib high speed considerable line tension throttle line moves start low speed operation pin moves out hole unlatching line slider No spring required cause move aft does moves away rib throttle can go back high speed interference have seen several other approaches simple coil springs actuate hook reflect unhappy experience rubberbands deteriorate racing fuel Basically release patterned after infallible pins cones used parachute ripcords hook released usual way momentary full-down elevator hook comes down due action coil spring pin attached hook moves down permitting torsion spring move rudder right second pin attached hook next releases spring-loaded wire fitting connected two flexible lanyards ripcords made 00 15 stranded control-line wire terminated short length music wire set bits brass tubing built wing flap roots pins pulled second coil spring flaps move down torsion springs left flap little longer right flap some roll input right flap moves down T-shaped pin rotates permit aileron move up fourth torsion spring mecha nism complex because self-actuating il ercetee/ roooreomtOFroOlore DEPLOTMENT SEQOENCC 2ornoesNomardrtr fri Oman release hook ore 00 tt OF15000k motes raetrOlniog * reap front Fodder SHook mcoe restrainelg pin gray lOntOrde tartarde releasing tirpe Hook tearhee porihve stop recar erLOCAMS moe20I tarboard trap raters restraint rotOtee ore Moraing aileron Fr ties Frtorte2 onlore re rOtE SLon terrOr 0000 leadauts moor Ott IIF atch ir requited itretOaLt_______________________________________ eero aro der flops ord rileror ore 02 retorted _______________________________________ ER- pr tomior J Learrot on032toeaerrer sot tatFLOt-mae area eF eereaaaOCrtitaotna tKonrr- teLOoPsi15-----50FF StOrS tonFTre FO0T0Ottrarero 0 sottce car prO OttteFse ,tc ore tot iii, \lJt r iM POR TO NT ii er EKELLONT CEOtONED AND DRAWN OY FRANK KELLY sequential has proven reliable must aligned perfectly however will require fine adjustment properly set up will maintain its adjustment long time strong competitors have no mechanism other arresting hook planeFs mechanical features could safely omitted serves useful purpose can get about 15 seconds per lap hook up compared 18 using everything rainy Saturday several years ago bent coat hanger form trigger ordinary Hot Rock control-line handle added second bellcrank old trainer son flew linked RC engine start carrier Matt still prefer homebrew handle commercial 3-line handles other carrier flier uses have flying carrier some time yourll probably want stick present handle youre accustomed Sunday flying Hot Rock handle give try cant beat price will feel natural fuselage design based few funda mentals has long nose tail moments give pitch stability desirable high speed horizontal tailplane area one-sixth wing area fuel tank location very important factor mounted directly behind engine front wing minimizes induced drag permits steady flow fuel both high low speeds uniflow tank recommended Although F4F gear retracted fuselage F6F gear retracted backward wing quarter twist AMA rules require scale gear location chose minimize drag streamlined aluminum gear mounted fuselage Conventional music wire gear could built wing better scale appearance should canted well forward reduce potential noseover landing Construction Before 5tart forewamed simple beginners model thin wing moderately complex mechanisms de mand patience care perform satisfactorily No elaborate tools required some modeling experience necessary Wing Lay bottom spar plans glue ribs Glue bottom trailing edges place Butt glue leading edge ribs Mount bellcrank platform securely glue top spar ribs Sight left wingtip toward bellcranks trim slots necessary assure freedom leadout wires move Note throttle line crosses down line Chamfer bottom trailing edge sheeting glue top sheeting After has dried glue top bottom sheeting once both sides Set down flat board weights pressing against spars Slip scrap 1/16 balsa leadout slots keep open Clamp top bottom sheets against rib leading edge using spring clothespins Make sure everything straight true let dry Cut additional slots now upper rear spars required install flush trailing edge top sheeting Mount cap strips top bottom Install bellcrank leadouts line slider Rib No II can sprung open receive L-shaped retaining wires Complete sheeting sand leading edge smooth contour sand entire assembly wing tips should longer necessary point Cut off 450 angle mount end caps angled slot left Trim sand Cut out flaps aileron Add scrap balsa close edges fixed moving parts Mount aileron hinges near top flap hinges near bottom Tail watched two early models disinte grate high-speed runs contests before learned about flutter Select good strong 3/16 balsa shcet use sturdy 3/32 wire join elevator halves Use two nylon RC hinges side action should smooth assembly must limber springy Fuselage fat fuselage F6Fr um soft balsa has adequate strength Under cut flush plywood doublers hook pivot point cut away accept hook After testing hook action plates may glued place Mount hardwood engine bearers ply wood doublers bend springy aluminum landing gear get scrap sheet metal about same thickness bend landing gear over scrap will have sharp bend may fracturer landing gear will have nice smooth bend radius Make axles screws using drill motor file Stainless steel music wire paper clips aluminum can soldered easily Sta Kleen flux Sta-Brite silver bearing solder stronger ordinary lead-tin solder Neutralize thoroughly solution baking soda water prevent corrosion Mount tail assembly securely fuselage assemble everything before cutting wing slot Find center gravity wing lying fuselage should o forward indicated position wing move wing until condition met cut slot epoxy wing firmly place using glass tape reinforce joint Paint tail 42 Model Aviation w w Cd w -J -J z -J w N -J -J U will move CG aft Springs Z-springs straightforward made music wire diameter bend angles can changed necessary achieve desired results coil springs diflicult make Put straight 8-inch length 093 music wire drill snag end piece 015 music wire thc jaws chuck Allow drill wrap thin wire 093 mandrel using thumb hold coils tightly together Stop before end wire reaches thumb will dig deep painful gouge Bend ends springs attachment stretch shorten necessary adjust spring constant Tuning Flying Now have new Hellcat built lets devote some space making perform properly First weigh should around 28 ounces Tigre people ask answer promptly 26 ounces Theres much can about now will have established psychological advan tage over competition CO location important though its too far forward will handle nicely wont go slow enough its too far aft may finish first flight Add weight necessary put CO within half inch indicated location Next check rudder assure Z-spring doesnt cause rudder prevent elevator returning neutral can result instant air disaster surc youre right Now check aileron flap position deployed aileron youve got better because provides yaw well roll drag good stuff laps ought have rest ptsition about 45 down equal Examine everything carefully freedom motion trim adjust necessary get smooth reliable action Fuss until whole thing operates perfectly time Pretty good isnt good enough Any slight tendency hang up certain demonstrated gifted competitor years biggest contest line slider different story five models Ive built like flops freely front back under weight leadouts have functioned infallibly meat contests centrifugal force high speed seems adequate slide leadouts way back spite minor misalignments have observed other line sliders oscillate free-acting model has no such tendency Now take everything out field go local elementary schoolyard set up portable carrier deck consists two pairs 5-lb scuba weights sash-cord arresting lines can hit can hit deck After years practice Im still batting about 300 50 work Consistency pays oIl Practice will also greatly improve low speed Learn just far can push save gracefully hope have much fun Hellcat hase need help write mc 7005 E Spring St. Long Beach CA 90808 call 213 429-9649 REFERENCI S Donald R Crawford Practical Gaide Airplane Pcrlir mance Design Crawford Asiation P0 Box 1262 Torrance CA 90505 979 John W R Taylor Combat Aircraft ol World Georec Rainbird Ltd. London 1969 I A Abbott E Von Doenhoit Theory wing Sections lMcGrase-HIl New York 1949 Willis Nyc Gramman Hellcat Mode 4irp/arte Ness Jane Jaly 1959 H Schonenberg Gramman Aerospace Corp. personal corn manication August 198043 peaing Ieaoounst pin nne enronuie tine excites ICdUUUL en attached pushrod release releases hook momentary full forward position during highspeed run Low speed center line toward down control Pin attached hook releases rudder airplane releases line slider move aft slot Wing flaps tail hook high-speed position basic design has built TBF Avenger SNJ Texanfly just well Flaps hook lowspeed position Spring lowers hook pin hook releases second spring pulls lanyards allowing flaps go down Wire Tpin rotates flap goes down permit ting aileron go up
Edition: Model Aviation - 1980/08
Page Numbers: 40, 41, 42, 43
Minor cuanges iusciag outline shape tail wing tips can change just about anything long moments areas retained Although models resembled prototypes earlier versions sometimes failed receive ten scale points under current rules scale fidelity F6F has challenged both high-and low-speed performance has satisfying Twominute low times consistently achieved realistic flight attitude official high speed 918 mph has recorded stock Tigre 1980 rules will clearly give scale spcn greater part war aviation cadet finally having first solo V-i Day fantasized lot about flying carriers never actually did fulfill boyhood dream vicariously now models reason training rushed completion success Grumman F6F Hellcat F4F Wildcat used exten sively early war US Navy Zero called Zeke faster maneuverable F6F changed course history outperforming Zero Altogether 12275 F6Fs built official records carrier deck An additional bonus awarded model closely resembles Navy carrier aircraft conflicting requirements constitute essence design challenge personally prefer Profile over Classes land II reason can design model instead simply select Although scoring system changed few years ago reduce emphasis high speed design philosophy remained same Design best high speed add refinements enhance low speed provided high-speed capability significantly affected 40 Model Aviation article will attempt show what also design Contrary popular notions drag necessarily minimized using short stubby wing higher aspect ratio wing has higher lift its easier fly both high low speeds Take look speed plane next meet rat racer Youll find winners have aspect ratios around 6 1 has Reynolds Number airspeed boundary layer separation chord greater about nine inches will start experience sharp increase parasitic drag above 90 mph wing area 300 sq span should 424 mean chord should 71 taper about 100 makes wing look enough better constant-chord wing justify little extra work certainly doesnt impair performance probably helps little rate establishes root chord 9 tip chord 525 early planes configuration adjustable leadout guides impressed difference high speed control low speed changes leadout placement already decided make next controllable heard someone else doing considerable success next version slightly shorter span accommo date greater tip chord leadouts could move farther have pronounced effect low speed Next considered wing design airfoil shape good general-purpose airfoil thickness 15% chord again borrow ing established speed technology chose 10% Back during Depression number people found employment tedious particularly useful government-sponsored program deriving empirical equations different airfoil shapes using slide rules mechanical calculators set about wind tunnels determine performance characteristics flaps various configurations NACA 4-digit series thickness camber extent location varied around basic streamline shape NACA 2410 airfoil used has 2% camber first digit centered 40% aft leading edge second digit has maximum thickness 10% chord last two digits centerline really two parabolas meet 2% up 40% aft basic streamline shape 10% thick wrapped around makes lower surface just about flat used formidable fifth-order equation exercise programming modern computer use work ultimately succeeded getting computer plot airfoil exact scales required elected use somewhat thinner symmetrical airfoil tip NACA 0007 provides slightly tapered wing just little washout tip common speed models tip chamfered bottom surface give currently popular shape said minimize tip vortices ribs undercut allow cap strips gives truer airfoil surface adds strength much added weight TBF models split flaps because prototype did used conventional flaps F6F NACA curves show 300 movement yields maximum lift set 450 because best low-speed performance some additional drag desirable expense lift Maintaining line tension low speed essential ways achieve simplest add tip weight added weight reduces acceleration critical first lap off deck high speed will authortook first Profile Carrier second B Proto Speed fourth Jet Speed atthe 1979 Nats Two-minute low times consistently achieved Hellcat realistic flight attitude official 918 mph high has recorded stock Tigre noticeably slower added weight plane flies very well no tip weight Ailerons make plane tend bank right extreme up elevator used low speed tends cause right turn rudder also moves right upon hook deployment Only right aileron made move induces differential drag introduces yaw right actions serve maintain line tension low speed release mechanism use little bit unusual tried design system latched high speed position driven low speed positions stored energy throttle leadout rigid 0032 wire has bent piece wire carefully soldered usual fine copper wire binding must posi tioned perfectly high speed wire pins brass line slider forward position slotted fiberglass tip rib high speed considerable line tension throttle line moves start low speed operation pin moves out hole unlatching line slider No spring required cause move aft does moves away rib throttle can go back high speed interference have seen several other approaches simple coil springs actuate hook reflect unhappy experience rubberbands deteriorate racing fuel Basically release patterned after infallible pins cones used parachute ripcords hook released usual way momentary full-down elevator hook comes down due action coil spring pin attached hook moves down permitting torsion spring move rudder right second pin attached hook next releases spring-loaded wire fitting connected two flexible lanyards ripcords made 00 15 stranded control-line wire terminated short length music wire set bits brass tubing built wing flap roots pins pulled second coil spring flaps move down torsion springs left flap little longer right flap some roll input right flap moves down T-shaped pin rotates permit aileron move up fourth torsion spring mecha nism complex because self-actuating il ercetee/ roooreomtOFroOlore DEPLOTMENT SEQOENCC 2ornoesNomardrtr fri Oman release hook ore 00 tt OF15000k motes raetrOlniog * reap front Fodder SHook mcoe restrainelg pin gray lOntOrde tartarde releasing tirpe Hook tearhee porihve stop recar erLOCAMS moe20I tarboard trap raters restraint rotOtee ore Moraing aileron Fr ties Frtorte2 onlore re rOtE SLon terrOr 0000 leadauts moor Ott IIF atch ir requited itretOaLt_______________________________________ eero aro der flops ord rileror ore 02 retorted _______________________________________ ER- pr tomior J Learrot on032toeaerrer sot tatFLOt-mae area eF eereaaaOCrtitaotna tKonrr- teLOoPsi15-----50FF StOrS tonFTre FO0T0Ottrarero 0 sottce car prO OttteFse ,tc ore tot iii, \lJt r iM POR TO NT ii er EKELLONT CEOtONED AND DRAWN OY FRANK KELLY sequential has proven reliable must aligned perfectly however will require fine adjustment properly set up will maintain its adjustment long time strong competitors have no mechanism other arresting hook planeFs mechanical features could safely omitted serves useful purpose can get about 15 seconds per lap hook up compared 18 using everything rainy Saturday several years ago bent coat hanger form trigger ordinary Hot Rock control-line handle added second bellcrank old trainer son flew linked RC engine start carrier Matt still prefer homebrew handle commercial 3-line handles other carrier flier uses have flying carrier some time yourll probably want stick present handle youre accustomed Sunday flying Hot Rock handle give try cant beat price will feel natural fuselage design based few funda mentals has long nose tail moments give pitch stability desirable high speed horizontal tailplane area one-sixth wing area fuel tank location very important factor mounted directly behind engine front wing minimizes induced drag permits steady flow fuel both high low speeds uniflow tank recommended Although F4F gear retracted fuselage F6F gear retracted backward wing quarter twist AMA rules require scale gear location chose minimize drag streamlined aluminum gear mounted fuselage Conventional music wire gear could built wing better scale appearance should canted well forward reduce potential noseover landing Construction Before 5tart forewamed simple beginners model thin wing moderately complex mechanisms de mand patience care perform satisfactorily No elaborate tools required some modeling experience necessary Wing Lay bottom spar plans glue ribs Glue bottom trailing edges place Butt glue leading edge ribs Mount bellcrank platform securely glue top spar ribs Sight left wingtip toward bellcranks trim slots necessary assure freedom leadout wires move Note throttle line crosses down line Chamfer bottom trailing edge sheeting glue top sheeting After has dried glue top bottom sheeting once both sides Set down flat board weights pressing against spars Slip scrap 1/16 balsa leadout slots keep open Clamp top bottom sheets against rib leading edge using spring clothespins Make sure everything straight true let dry Cut additional slots now upper rear spars required install flush trailing edge top sheeting Mount cap strips top bottom Install bellcrank leadouts line slider Rib No II can sprung open receive L-shaped retaining wires Complete sheeting sand leading edge smooth contour sand entire assembly wing tips should longer necessary point Cut off 450 angle mount end caps angled slot left Trim sand Cut out flaps aileron Add scrap balsa close edges fixed moving parts Mount aileron hinges near top flap hinges near bottom Tail watched two early models disinte grate high-speed runs contests before learned about flutter Select good strong 3/16 balsa shcet use sturdy 3/32 wire join elevator halves Use two nylon RC hinges side action should smooth assembly must limber springy Fuselage fat fuselage F6Fr um soft balsa has adequate strength Under cut flush plywood doublers hook pivot point cut away accept hook After testing hook action plates may glued place Mount hardwood engine bearers ply wood doublers bend springy aluminum landing gear get scrap sheet metal about same thickness bend landing gear over scrap will have sharp bend may fracturer landing gear will have nice smooth bend radius Make axles screws using drill motor file Stainless steel music wire paper clips aluminum can soldered easily Sta Kleen flux Sta-Brite silver bearing solder stronger ordinary lead-tin solder Neutralize thoroughly solution baking soda water prevent corrosion Mount tail assembly securely fuselage assemble everything before cutting wing slot Find center gravity wing lying fuselage should o forward indicated position wing move wing until condition met cut slot epoxy wing firmly place using glass tape reinforce joint Paint tail 42 Model Aviation w w Cd w -J -J z -J w N -J -J U will move CG aft Springs Z-springs straightforward made music wire diameter bend angles can changed necessary achieve desired results coil springs diflicult make Put straight 8-inch length 093 music wire drill snag end piece 015 music wire thc jaws chuck Allow drill wrap thin wire 093 mandrel using thumb hold coils tightly together Stop before end wire reaches thumb will dig deep painful gouge Bend ends springs attachment stretch shorten necessary adjust spring constant Tuning Flying Now have new Hellcat built lets devote some space making perform properly First weigh should around 28 ounces Tigre people ask answer promptly 26 ounces Theres much can about now will have established psychological advan tage over competition CO location important though its too far forward will handle nicely wont go slow enough its too far aft may finish first flight Add weight necessary put CO within half inch indicated location Next check rudder assure Z-spring doesnt cause rudder prevent elevator returning neutral can result instant air disaster surc youre right Now check aileron flap position deployed aileron youve got better because provides yaw well roll drag good stuff laps ought have rest ptsition about 45 down equal Examine everything carefully freedom motion trim adjust necessary get smooth reliable action Fuss until whole thing operates perfectly time Pretty good isnt good enough Any slight tendency hang up certain demonstrated gifted competitor years biggest contest line slider different story five models Ive built like flops freely front back under weight leadouts have functioned infallibly meat contests centrifugal force high speed seems adequate slide leadouts way back spite minor misalignments have observed other line sliders oscillate free-acting model has no such tendency Now take everything out field go local elementary schoolyard set up portable carrier deck consists two pairs 5-lb scuba weights sash-cord arresting lines can hit can hit deck After years practice Im still batting about 300 50 work Consistency pays oIl Practice will also greatly improve low speed Learn just far can push save gracefully hope have much fun Hellcat hase need help write mc 7005 E Spring St. Long Beach CA 90808 call 213 429-9649 REFERENCI S Donald R Crawford Practical Gaide Airplane Pcrlir mance Design Crawford Asiation P0 Box 1262 Torrance CA 90505 979 John W R Taylor Combat Aircraft ol World Georec Rainbird Ltd. London 1969 I A Abbott E Von Doenhoit Theory wing Sections lMcGrase-HIl New York 1949 Willis Nyc Gramman Hellcat Mode 4irp/arte Ness Jane Jaly 1959 H Schonenberg Gramman Aerospace Corp. personal corn manication August 198043 peaing Ieaoounst pin nne enronuie tine excites ICdUUUL en attached pushrod release releases hook momentary full forward position during highspeed run Low speed center line toward down control Pin attached hook releases rudder airplane releases line slider move aft slot Wing flaps tail hook high-speed position basic design has built TBF Avenger SNJ Texanfly just well Flaps hook lowspeed position Spring lowers hook pin hook releases second spring pulls lanyards allowing flaps go down Wire Tpin rotates flap goes down permit ting aileron go up
Edition: Model Aviation - 1980/08
Page Numbers: 40, 41, 42, 43
Minor cuanges iusciag outline shape tail wing tips can change just about anything long moments areas retained Although models resembled prototypes earlier versions sometimes failed receive ten scale points under current rules scale fidelity F6F has challenged both high-and low-speed performance has satisfying Twominute low times consistently achieved realistic flight attitude official high speed 918 mph has recorded stock Tigre 1980 rules will clearly give scale spcn greater part war aviation cadet finally having first solo V-i Day fantasized lot about flying carriers never actually did fulfill boyhood dream vicariously now models reason training rushed completion success Grumman F6F Hellcat F4F Wildcat used exten sively early war US Navy Zero called Zeke faster maneuverable F6F changed course history outperforming Zero Altogether 12275 F6Fs built official records carrier deck An additional bonus awarded model closely resembles Navy carrier aircraft conflicting requirements constitute essence design challenge personally prefer Profile over Classes land II reason can design model instead simply select Although scoring system changed few years ago reduce emphasis high speed design philosophy remained same Design best high speed add refinements enhance low speed provided high-speed capability significantly affected 40 Model Aviation article will attempt show what also design Contrary popular notions drag necessarily minimized using short stubby wing higher aspect ratio wing has higher lift its easier fly both high low speeds Take look speed plane next meet rat racer Youll find winners have aspect ratios around 6 1 has Reynolds Number airspeed boundary layer separation chord greater about nine inches will start experience sharp increase parasitic drag above 90 mph wing area 300 sq span should 424 mean chord should 71 taper about 100 makes wing look enough better constant-chord wing justify little extra work certainly doesnt impair performance probably helps little rate establishes root chord 9 tip chord 525 early planes configuration adjustable leadout guides impressed difference high speed control low speed changes leadout placement already decided make next controllable heard someone else doing considerable success next version slightly shorter span accommo date greater tip chord leadouts could move farther have pronounced effect low speed Next considered wing design airfoil shape good general-purpose airfoil thickness 15% chord again borrow ing established speed technology chose 10% Back during Depression number people found employment tedious particularly useful government-sponsored program deriving empirical equations different airfoil shapes using slide rules mechanical calculators set about wind tunnels determine performance characteristics flaps various configurations NACA 4-digit series thickness camber extent location varied around basic streamline shape NACA 2410 airfoil used has 2% camber first digit centered 40% aft leading edge second digit has maximum thickness 10% chord last two digits centerline really two parabolas meet 2% up 40% aft basic streamline shape 10% thick wrapped around makes lower surface just about flat used formidable fifth-order equation exercise programming modern computer use work ultimately succeeded getting computer plot airfoil exact scales required elected use somewhat thinner symmetrical airfoil tip NACA 0007 provides slightly tapered wing just little washout tip common speed models tip chamfered bottom surface give currently popular shape said minimize tip vortices ribs undercut allow cap strips gives truer airfoil surface adds strength much added weight TBF models split flaps because prototype did used conventional flaps F6F NACA curves show 300 movement yields maximum lift set 450 because best low-speed performance some additional drag desirable expense lift Maintaining line tension low speed essential ways achieve simplest add tip weight added weight reduces acceleration critical first lap off deck high speed will authortook first Profile Carrier second B Proto Speed fourth Jet Speed atthe 1979 Nats Two-minute low times consistently achieved Hellcat realistic flight attitude official 918 mph high has recorded stock Tigre noticeably slower added weight plane flies very well no tip weight Ailerons make plane tend bank right extreme up elevator used low speed tends cause right turn rudder also moves right upon hook deployment Only right aileron made move induces differential drag introduces yaw right actions serve maintain line tension low speed release mechanism use little bit unusual tried design system latched high speed position driven low speed positions stored energy throttle leadout rigid 0032 wire has bent piece wire carefully soldered usual fine copper wire binding must posi tioned perfectly high speed wire pins brass line slider forward position slotted fiberglass tip rib high speed considerable line tension throttle line moves start low speed operation pin moves out hole unlatching line slider No spring required cause move aft does moves away rib throttle can go back high speed interference have seen several other approaches simple coil springs actuate hook reflect unhappy experience rubberbands deteriorate racing fuel Basically release patterned after infallible pins cones used parachute ripcords hook released usual way momentary full-down elevator hook comes down due action coil spring pin attached hook moves down permitting torsion spring move rudder right second pin attached hook next releases spring-loaded wire fitting connected two flexible lanyards ripcords made 00 15 stranded control-line wire terminated short length music wire set bits brass tubing built wing flap roots pins pulled second coil spring flaps move down torsion springs left flap little longer right flap some roll input right flap moves down T-shaped pin rotates permit aileron move up fourth torsion spring mecha nism complex because self-actuating il ercetee/ roooreomtOFroOlore DEPLOTMENT SEQOENCC 2ornoesNomardrtr fri Oman release hook ore 00 tt OF15000k motes raetrOlniog * reap front Fodder SHook mcoe restrainelg pin gray lOntOrde tartarde releasing tirpe Hook tearhee porihve stop recar erLOCAMS moe20I tarboard trap raters restraint rotOtee ore Moraing aileron Fr ties Frtorte2 onlore re rOtE SLon terrOr 0000 leadauts moor Ott IIF atch ir requited itretOaLt_______________________________________ eero aro der flops ord rileror ore 02 retorted _______________________________________ ER- pr tomior J Learrot on032toeaerrer sot tatFLOt-mae area eF eereaaaOCrtitaotna tKonrr- teLOoPsi15-----50FF StOrS tonFTre FO0T0Ottrarero 0 sottce car prO OttteFse ,tc ore tot iii, \lJt r iM POR TO NT ii er EKELLONT CEOtONED AND DRAWN OY FRANK KELLY sequential has proven reliable must aligned perfectly however will require fine adjustment properly set up will maintain its adjustment long time strong competitors have no mechanism other arresting hook planeFs mechanical features could safely omitted serves useful purpose can get about 15 seconds per lap hook up compared 18 using everything rainy Saturday several years ago bent coat hanger form trigger ordinary Hot Rock control-line handle added second bellcrank old trainer son flew linked RC engine start carrier Matt still prefer homebrew handle commercial 3-line handles other carrier flier uses have flying carrier some time yourll probably want stick present handle youre accustomed Sunday flying Hot Rock handle give try cant beat price will feel natural fuselage design based few funda mentals has long nose tail moments give pitch stability desirable high speed horizontal tailplane area one-sixth wing area fuel tank location very important factor mounted directly behind engine front wing minimizes induced drag permits steady flow fuel both high low speeds uniflow tank recommended Although F4F gear retracted fuselage F6F gear retracted backward wing quarter twist AMA rules require scale gear location chose minimize drag streamlined aluminum gear mounted fuselage Conventional music wire gear could built wing better scale appearance should canted well forward reduce potential noseover landing Construction Before 5tart forewamed simple beginners model thin wing moderately complex mechanisms de mand patience care perform satisfactorily No elaborate tools required some modeling experience necessary Wing Lay bottom spar plans glue ribs Glue bottom trailing edges place Butt glue leading edge ribs Mount bellcrank platform securely glue top spar ribs Sight left wingtip toward bellcranks trim slots necessary assure freedom leadout wires move Note throttle line crosses down line Chamfer bottom trailing edge sheeting glue top sheeting After has dried glue top bottom sheeting once both sides Set down flat board weights pressing against spars Slip scrap 1/16 balsa leadout slots keep open Clamp top bottom sheets against rib leading edge using spring clothespins Make sure everything straight true let dry Cut additional slots now upper rear spars required install flush trailing edge top sheeting Mount cap strips top bottom Install bellcrank leadouts line slider Rib No II can sprung open receive L-shaped retaining wires Complete sheeting sand leading edge smooth contour sand entire assembly wing tips should longer necessary point Cut off 450 angle mount end caps angled slot left Trim sand Cut out flaps aileron Add scrap balsa close edges fixed moving parts Mount aileron hinges near top flap hinges near bottom Tail watched two early models disinte grate high-speed runs contests before learned about flutter Select good strong 3/16 balsa shcet use sturdy 3/32 wire join elevator halves Use two nylon RC hinges side action should smooth assembly must limber springy Fuselage fat fuselage F6Fr um soft balsa has adequate strength Under cut flush plywood doublers hook pivot point cut away accept hook After testing hook action plates may glued place Mount hardwood engine bearers ply wood doublers bend springy aluminum landing gear get scrap sheet metal about same thickness bend landing gear over scrap will have sharp bend may fracturer landing gear will have nice smooth bend radius Make axles screws using drill motor file Stainless steel music wire paper clips aluminum can soldered easily Sta Kleen flux Sta-Brite silver bearing solder stronger ordinary lead-tin solder Neutralize thoroughly solution baking soda water prevent corrosion Mount tail assembly securely fuselage assemble everything before cutting wing slot Find center gravity wing lying fuselage should o forward indicated position wing move wing until condition met cut slot epoxy wing firmly place using glass tape reinforce joint Paint tail 42 Model Aviation w w Cd w -J -J z -J w N -J -J U will move CG aft Springs Z-springs straightforward made music wire diameter bend angles can changed necessary achieve desired results coil springs diflicult make Put straight 8-inch length 093 music wire drill snag end piece 015 music wire thc jaws chuck Allow drill wrap thin wire 093 mandrel using thumb hold coils tightly together Stop before end wire reaches thumb will dig deep painful gouge Bend ends springs attachment stretch shorten necessary adjust spring constant Tuning Flying Now have new Hellcat built lets devote some space making perform properly First weigh should around 28 ounces Tigre people ask answer promptly 26 ounces Theres much can about now will have established psychological advan tage over competition CO location important though its too far forward will handle nicely wont go slow enough its too far aft may finish first flight Add weight necessary put CO within half inch indicated location Next check rudder assure Z-spring doesnt cause rudder prevent elevator returning neutral can result instant air disaster surc youre right Now check aileron flap position deployed aileron youve got better because provides yaw well roll drag good stuff laps ought have rest ptsition about 45 down equal Examine everything carefully freedom motion trim adjust necessary get smooth reliable action Fuss until whole thing operates perfectly time Pretty good isnt good enough Any slight tendency hang up certain demonstrated gifted competitor years biggest contest line slider different story five models Ive built like flops freely front back under weight leadouts have functioned infallibly meat contests centrifugal force high speed seems adequate slide leadouts way back spite minor misalignments have observed other line sliders oscillate free-acting model has no such tendency Now take everything out field go local elementary schoolyard set up portable carrier deck consists two pairs 5-lb scuba weights sash-cord arresting lines can hit can hit deck After years practice Im still batting about 300 50 work Consistency pays oIl Practice will also greatly improve low speed Learn just far can push save gracefully hope have much fun Hellcat hase need help write mc 7005 E Spring St. Long Beach CA 90808 call 213 429-9649 REFERENCI S Donald R Crawford Practical Gaide Airplane Pcrlir mance Design Crawford Asiation P0 Box 1262 Torrance CA 90505 979 John W R Taylor Combat Aircraft ol World Georec Rainbird Ltd. London 1969 I A Abbott E Von Doenhoit Theory wing Sections lMcGrase-HIl New York 1949 Willis Nyc Gramman Hellcat Mode 4irp/arte Ness Jane Jaly 1959 H Schonenberg Gramman Aerospace Corp. personal corn manication August 198043 peaing Ieaoounst pin nne enronuie tine excites ICdUUUL en attached pushrod release releases hook momentary full forward position during highspeed run Low speed center line toward down control Pin attached hook releases rudder airplane releases line slider move aft slot Wing flaps tail hook high-speed position basic design has built TBF Avenger SNJ Texanfly just well Flaps hook lowspeed position Spring lowers hook pin hook releases second spring pulls lanyards allowing flaps go down Wire Tpin rotates flap goes down permit ting aileron go up
Edition: Model Aviation - 1980/08
Page Numbers: 40, 41, 42, 43
Minor cuanges iusciag outline shape tail wing tips can change just about anything long moments areas retained Although models resembled prototypes earlier versions sometimes failed receive ten scale points under current rules scale fidelity F6F has challenged both high-and low-speed performance has satisfying Twominute low times consistently achieved realistic flight attitude official high speed 918 mph has recorded stock Tigre 1980 rules will clearly give scale spcn greater part war aviation cadet finally having first solo V-i Day fantasized lot about flying carriers never actually did fulfill boyhood dream vicariously now models reason training rushed completion success Grumman F6F Hellcat F4F Wildcat used exten sively early war US Navy Zero called Zeke faster maneuverable F6F changed course history outperforming Zero Altogether 12275 F6Fs built official records carrier deck An additional bonus awarded model closely resembles Navy carrier aircraft conflicting requirements constitute essence design challenge personally prefer Profile over Classes land II reason can design model instead simply select Although scoring system changed few years ago reduce emphasis high speed design philosophy remained same Design best high speed add refinements enhance low speed provided high-speed capability significantly affected 40 Model Aviation article will attempt show what also design Contrary popular notions drag necessarily minimized using short stubby wing higher aspect ratio wing has higher lift its easier fly both high low speeds Take look speed plane next meet rat racer Youll find winners have aspect ratios around 6 1 has Reynolds Number airspeed boundary layer separation chord greater about nine inches will start experience sharp increase parasitic drag above 90 mph wing area 300 sq span should 424 mean chord should 71 taper about 100 makes wing look enough better constant-chord wing justify little extra work certainly doesnt impair performance probably helps little rate establishes root chord 9 tip chord 525 early planes configuration adjustable leadout guides impressed difference high speed control low speed changes leadout placement already decided make next controllable heard someone else doing considerable success next version slightly shorter span accommo date greater tip chord leadouts could move farther have pronounced effect low speed Next considered wing design airfoil shape good general-purpose airfoil thickness 15% chord again borrow ing established speed technology chose 10% Back during Depression number people found employment tedious particularly useful government-sponsored program deriving empirical equations different airfoil shapes using slide rules mechanical calculators set about wind tunnels determine performance characteristics flaps various configurations NACA 4-digit series thickness camber extent location varied around basic streamline shape NACA 2410 airfoil used has 2% camber first digit centered 40% aft leading edge second digit has maximum thickness 10% chord last two digits centerline really two parabolas meet 2% up 40% aft basic streamline shape 10% thick wrapped around makes lower surface just about flat used formidable fifth-order equation exercise programming modern computer use work ultimately succeeded getting computer plot airfoil exact scales required elected use somewhat thinner symmetrical airfoil tip NACA 0007 provides slightly tapered wing just little washout tip common speed models tip chamfered bottom surface give currently popular shape said minimize tip vortices ribs undercut allow cap strips gives truer airfoil surface adds strength much added weight TBF models split flaps because prototype did used conventional flaps F6F NACA curves show 300 movement yields maximum lift set 450 because best low-speed performance some additional drag desirable expense lift Maintaining line tension low speed essential ways achieve simplest add tip weight added weight reduces acceleration critical first lap off deck high speed will authortook first Profile Carrier second B Proto Speed fourth Jet Speed atthe 1979 Nats Two-minute low times consistently achieved Hellcat realistic flight attitude official 918 mph high has recorded stock Tigre noticeably slower added weight plane flies very well no tip weight Ailerons make plane tend bank right extreme up elevator used low speed tends cause right turn rudder also moves right upon hook deployment Only right aileron made move induces differential drag introduces yaw right actions serve maintain line tension low speed release mechanism use little bit unusual tried design system latched high speed position driven low speed positions stored energy throttle leadout rigid 0032 wire has bent piece wire carefully soldered usual fine copper wire binding must posi tioned perfectly high speed wire pins brass line slider forward position slotted fiberglass tip rib high speed considerable line tension throttle line moves start low speed operation pin moves out hole unlatching line slider No spring required cause move aft does moves away rib throttle can go back high speed interference have seen several other approaches simple coil springs actuate hook reflect unhappy experience rubberbands deteriorate racing fuel Basically release patterned after infallible pins cones used parachute ripcords hook released usual way momentary full-down elevator hook comes down due action coil spring pin attached hook moves down permitting torsion spring move rudder right second pin attached hook next releases spring-loaded wire fitting connected two flexible lanyards ripcords made 00 15 stranded control-line wire terminated short length music wire set bits brass tubing built wing flap roots pins pulled second coil spring flaps move down torsion springs left flap little longer right flap some roll input right flap moves down T-shaped pin rotates permit aileron move up fourth torsion spring mecha nism complex because self-actuating il ercetee/ roooreomtOFroOlore DEPLOTMENT SEQOENCC 2ornoesNomardrtr fri Oman release hook ore 00 tt OF15000k motes raetrOlniog * reap front Fodder SHook mcoe restrainelg pin gray lOntOrde tartarde releasing tirpe Hook tearhee porihve stop recar erLOCAMS moe20I tarboard trap raters restraint rotOtee ore Moraing aileron Fr ties Frtorte2 onlore re rOtE SLon terrOr 0000 leadauts moor Ott IIF atch ir requited itretOaLt_______________________________________ eero aro der flops ord rileror ore 02 retorted _______________________________________ ER- pr tomior J Learrot on032toeaerrer sot tatFLOt-mae area eF eereaaaOCrtitaotna tKonrr- teLOoPsi15-----50FF StOrS tonFTre FO0T0Ottrarero 0 sottce car prO OttteFse ,tc ore tot iii, \lJt r iM POR TO NT ii er EKELLONT CEOtONED AND DRAWN OY FRANK KELLY sequential has proven reliable must aligned perfectly however will require fine adjustment properly set up will maintain its adjustment long time strong competitors have no mechanism other arresting hook planeFs mechanical features could safely omitted serves useful purpose can get about 15 seconds per lap hook up compared 18 using everything rainy Saturday several years ago bent coat hanger form trigger ordinary Hot Rock control-line handle added second bellcrank old trainer son flew linked RC engine start carrier Matt still prefer homebrew handle commercial 3-line handles other carrier flier uses have flying carrier some time yourll probably want stick present handle youre accustomed Sunday flying Hot Rock handle give try cant beat price will feel natural fuselage design based few funda mentals has long nose tail moments give pitch stability desirable high speed horizontal tailplane area one-sixth wing area fuel tank location very important factor mounted directly behind engine front wing minimizes induced drag permits steady flow fuel both high low speeds uniflow tank recommended Although F4F gear retracted fuselage F6F gear retracted backward wing quarter twist AMA rules require scale gear location chose minimize drag streamlined aluminum gear mounted fuselage Conventional music wire gear could built wing better scale appearance should canted well forward reduce potential noseover landing Construction Before 5tart forewamed simple beginners model thin wing moderately complex mechanisms de mand patience care perform satisfactorily No elaborate tools required some modeling experience necessary Wing Lay bottom spar plans glue ribs Glue bottom trailing edges place Butt glue leading edge ribs Mount bellcrank platform securely glue top spar ribs Sight left wingtip toward bellcranks trim slots necessary assure freedom leadout wires move Note throttle line crosses down line Chamfer bottom trailing edge sheeting glue top sheeting After has dried glue top bottom sheeting once both sides Set down flat board weights pressing against spars Slip scrap 1/16 balsa leadout slots keep open Clamp top bottom sheets against rib leading edge using spring clothespins Make sure everything straight true let dry Cut additional slots now upper rear spars required install flush trailing edge top sheeting Mount cap strips top bottom Install bellcrank leadouts line slider Rib No II can sprung open receive L-shaped retaining wires Complete sheeting sand leading edge smooth contour sand entire assembly wing tips should longer necessary point Cut off 450 angle mount end caps angled slot left Trim sand Cut out flaps aileron Add scrap balsa close edges fixed moving parts Mount aileron hinges near top flap hinges near bottom Tail watched two early models disinte grate high-speed runs contests before learned about flutter Select good strong 3/16 balsa shcet use sturdy 3/32 wire join elevator halves Use two nylon RC hinges side action should smooth assembly must limber springy Fuselage fat fuselage F6Fr um soft balsa has adequate strength Under cut flush plywood doublers hook pivot point cut away accept hook After testing hook action plates may glued place Mount hardwood engine bearers ply wood doublers bend springy aluminum landing gear get scrap sheet metal about same thickness bend landing gear over scrap will have sharp bend may fracturer landing gear will have nice smooth bend radius Make axles screws using drill motor file Stainless steel music wire paper clips aluminum can soldered easily Sta Kleen flux Sta-Brite silver bearing solder stronger ordinary lead-tin solder Neutralize thoroughly solution baking soda water prevent corrosion Mount tail assembly securely fuselage assemble everything before cutting wing slot Find center gravity wing lying fuselage should o forward indicated position wing move wing until condition met cut slot epoxy wing firmly place using glass tape reinforce joint Paint tail 42 Model Aviation w w Cd w -J -J z -J w N -J -J U will move CG aft Springs Z-springs straightforward made music wire diameter bend angles can changed necessary achieve desired results coil springs diflicult make Put straight 8-inch length 093 music wire drill snag end piece 015 music wire thc jaws chuck Allow drill wrap thin wire 093 mandrel using thumb hold coils tightly together Stop before end wire reaches thumb will dig deep painful gouge Bend ends springs attachment stretch shorten necessary adjust spring constant Tuning Flying Now have new Hellcat built lets devote some space making perform properly First weigh should around 28 ounces Tigre people ask answer promptly 26 ounces Theres much can about now will have established psychological advan tage over competition CO location important though its too far forward will handle nicely wont go slow enough its too far aft may finish first flight Add weight necessary put CO within half inch indicated location Next check rudder assure Z-spring doesnt cause rudder prevent elevator returning neutral can result instant air disaster surc youre right Now check aileron flap position deployed aileron youve got better because provides yaw well roll drag good stuff laps ought have rest ptsition about 45 down equal Examine everything carefully freedom motion trim adjust necessary get smooth reliable action Fuss until whole thing operates perfectly time Pretty good isnt good enough Any slight tendency hang up certain demonstrated gifted competitor years biggest contest line slider different story five models Ive built like flops freely front back under weight leadouts have functioned infallibly meat contests centrifugal force high speed seems adequate slide leadouts way back spite minor misalignments have observed other line sliders oscillate free-acting model has no such tendency Now take everything out field go local elementary schoolyard set up portable carrier deck consists two pairs 5-lb scuba weights sash-cord arresting lines can hit can hit deck After years practice Im still batting about 300 50 work Consistency pays oIl Practice will also greatly improve low speed Learn just far can push save gracefully hope have much fun Hellcat hase need help write mc 7005 E Spring St. Long Beach CA 90808 call 213 429-9649 REFERENCI S Donald R Crawford Practical Gaide Airplane Pcrlir mance Design Crawford Asiation P0 Box 1262 Torrance CA 90505 979 John W R Taylor Combat Aircraft ol World Georec Rainbird Ltd. London 1969 I A Abbott E Von Doenhoit Theory wing Sections lMcGrase-HIl New York 1949 Willis Nyc Gramman Hellcat Mode 4irp/arte Ness Jane Jaly 1959 H Schonenberg Gramman Aerospace Corp. personal corn manication August 198043 peaing Ieaoounst pin nne enronuie tine excites ICdUUUL en attached pushrod release releases hook momentary full forward position during highspeed run Low speed center line toward down control Pin attached hook releases rudder airplane releases line slider move aft slot Wing flaps tail hook high-speed position basic design has built TBF Avenger SNJ Texanfly just well Flaps hook lowspeed position Spring lowers hook pin hook releases second spring pulls lanyards allowing flaps go down Wire Tpin rotates flap goes down permit ting aileron go up