look correct problems EWilliam F McCombs PART ONE two-part article discussed combined influence vertical tail size total effective dihedral models stability flightand piloted airplanes influence vertical tail size in-flight controllability months conclusion explains adjust vertical tail size correct problems show up flight discusses achieve reasonable vertical tail area during design stage explains turning trim wing dihedral effective dihedral summary appendices included end article Tailoring tail two cases model has flown has troublesome other new unflown model 1 Existing troublesome modelProceed follows 2 below a If has trouble such wandering flight insensitivity small side thrust tail incidence changes mild severe Dutch roll glue small additional amount tail areaabout 5% existing areaand fly again Repeat necessary until trouble disappears b If has trouble such turning flight being very sensitive small side thrust tail incidence changes initial burst power Rubber models rendering incapable achieving steep climb because rolloff undesired spiraling simple solution same solution applies Free Flight Scale model will climb fly level because always spiraling down solution cut away little vertical tail areaabout 5% existing areaand fly again Repeat necessary until trouble disappears course must adequate minimum dihedral Free Flight Scale FFS model hinging rudder portion often adequate discussed 2 A new unflown modelThe procedure get approximately right size tail before flying avoid possible harm initial flights Start sheet balsa tail trim model good straight no turning slow hand-launched glide no stalling preferably good height standing table car longer glide better detect Dutch roll launch model its glide wing banked say left wing down about 400 properly launched model should quickly roll out its left bank glide straight turns right Dutch roll present Dutch roll the right turn glide long enough will turn left right etc shown Section la Part last month eliminate Dutch roll glue small amount tail area between successive glides Section la Part no Dutch roll seen cut away tail area small amountssay 5% existing areabetween successive glides until Dutch roll detected eliminate discussed above procedure will give very nearly right size tail beginning powered flights troubles section 1 shows up very small change tail area will eliminate sheet balsa tail can replaced built-up desired Rubber model prop doesnt freewbeel fold fix vertical position glide tests folds replace gliding very low powered straight level descending flights launching model wings banked suggested previously new FFS model another approach above rudder portion removed no very little Dutch roll model should alright rudder hinged float freely Dutch roll shows up later make horn area part fin still occurs increase fin area small amounts until disappears procedure will result smaller scale deviation can achieved using one-piece tail reducing entire tail area required per above tests particularly tail large floating rudder portion will also allow Old-Timer FF models large tails climb steeply desired About turning trim bad spiraling may course due bad trim rather spiral instability trim changes wont correct spiral instability 52 Model Aviation key optimal flight stability tailoring models vertical tail both during design stage after initial flight testing conclusion two-part article author tells what known cause Too much turning trim will cause tight turn too much banking spiral dive such tight turn wanted glide indoor flying wing warping used keep wing level usually done washinwarping trailing edge wing inside turn eg left wing left turn downward down aileron About 130 wing tip used depending upon turn tighter turn washin needed non-Scale Indoor models instead using wing warping wing usually offset slightly sideto left left turnabout 3-5% wingspan Using tilted stabilizer setting instead vertical tail rudder incidence produce gliding slow cruising turn preferred non-Scale models since effect essentially disappears during high-powered flight powered flight turn trimmed side thrust often fine-tuned small tail tab downthrust adjusted get desired upward climb model has trimmed turn direction using wing warping wing offset should made fly other direction will spiral crash unless wing warping wing offset removed high-powered steep-climbing FF Duration model launched flight must pointed steeply upward Otherwise will usually dive crash before can get its steep-climbing attitude Wing dihedral effective dihedral understand some PES models need wing dihedral others needs know about effective dihedral anything has same effect wing dihedral producing rolling effect whenever model sideslipie yawed attitude following main sources FFS models plus s good effect such dihedral minus - means negative effect such cathedral anhedral 1 Wing position high wing generates about 10 30 effective dihedral midwing generates low wing generates about 10 3O values typical nose forward fuselage sizes Scale models full-scale airplanes larger fatter nose greater effect vice-versa effect negligible Duration models have slim noses FFS models reasonable assume 20 high-wings 2o low-wings formula available see Appendix estimating closely 2 Wing tip shape As seen front view lower surface slants upward very abruptly meet upper surface about 1/20 effective dihedral generated upper surface slants downward meet lower surface about 2/20 generated both surfaces slant tip blunt rounded no effective dihedral generated values low-speed slow gliding slow cruising flight become less trimmed speed increases ie lift coefficient decreases 3 Wing aspect ratio wingspan age chord wingspan2 -i- wing area values approximately table below low-speed flight 2 above becoming smaller speed increases needed given model finds sum effective dihedral values 1 through 4 above subtracts sum 50 40 Indoor FFS models Outdoor FFS models doing gives wing dihedral 10 high-wings 30 midwings 50 low-wings 30 biplanes However relatively large vertical tail present small dihedral duration will suffer spiral instability may occur Either dihedral smaller tail will required prevent suggested glide test adequate minimum dihedral follows head height launched forward gliding speed wings banked about 400 model should roll out its banked attitude before landing Formula vertical tail area Although Wing Aspect Ratio 11/2221/2 331/244/o551/268 Effective Dihedral 370200 120 91/20 61/2040 31/2030 21/20 20 11/20 Note Dihedral needed during low-speed flight high-speed flight 4 Wing sweepback measured one-fourth-chord line values approximately table below forward sweep numbers negative values low-speed flight 2 3 above Sweepback Angle 00 100 200 300 400 450 Effective Dihedral 00 2 1/20 50 80 110 140 Therefore given FFS model total effective dihedral algebraic sum wing dihedral other effective dihedral may have lues above total effective dihedral just wing dihedral determines quickly model will return its trimmed attitude upset laterally banked gusty air example reasonably small tail model having 60 total dihedral will correct its attitude 60/120 half quickly has 120 Duration models have generous dihedral better duration large tail slows down recovery time hurting duration particularly total effective dihedral small FFS models Outdoor FFS models need about 50 total effective dihedral practical minimum gusty air Indoor models need about 40 always desirable better duration less crash damage risk greater scale deviation Therefore determine much wing dihedral proper small size tail can found flying previously discussed following formula will give fairly good estimate beginning flight tests AvNxAw xb/Lv where Av Verticaltailareainsqin Aw Wi ng area sq bWingspan inches Lv Distance inches CG aft center tail area N numerical factor given table below April 1992 53 Type FF ModelN Nordic class Glider006 Hand-Launched Glider015 Indoor Duration Microfilm018 Other Indoor Duration028 Gas-powered Duration023 Outdoor Rubber Duration033 Gas-powered Scale027 Rubber-powered Scale Speed035 above biplanes use formula below 1 means upper wing 2 means lower wing Av 9N [A1 x b1 b2] ther things being about equal low-wing model will found require smaller tail will high-wing model Sport fun models can have 1JL g These thirties-era Free Flight Gas models have taIls much too large todays standards generous dihedral unlike Scale models need climb steeply unlike Duration models hence need small tail required desired tail can two three times large Scale Duration planes small tail always preferable Scale model having generous dihedral really sport model ndix following formula can used estimate effective dihedral due wing position wing mounted cabane struts drLow Wing Effective dihedral* bA *in degrees area Depth fuselage station 1/3 distance between wings leading edge LE front nose block w h fuselage above station h htofwingsLE above below midpoint d above h w low wing h - hd use hd b Wingspan dimensions inches effective dihedral maximum ng mounted top bottom fuselage located above below fuselage using cabane struts resulting gap causes effective dihedral decrease Referring figure below can calculated Effective dihedral mum effective dihedral x 1 4gIb g between wing fuselage maximum effective dihedral lculated assuming wing located top bottom fuselage formula applies long gap no b/4 gCabana Struts gpIi Filling gap single piece thin clear plastic sheet leading edge trailing edge helps high-wing giving effective dihedral per first formula following table shows calculated effective dihedral due wing position several representative airplanes Table A-i Effective Dihedral due Wing Position AirplaneDihedral AirplaneDihedral Aeronca LB LC-1 20Vought F4U Corsair2 50 Bell P-39 Airacobra240Vought V-143210 Curtiss P-40 Warhawk150Bede B0-4350 Focke-Wuif Ta 152130Corben Super Ace230 Davis DA-2Aj70Curtiss Robin150 Grumman F6F Hellcat140Fairchild 2425 Hawker Hurricane120Howard Mr Mulligan4Q0 Heinkel 1000-11Lockheed Vega240 Jodel 0-9 JoMonocoupe 90A240 Messerschmitt Bf 109e180Nesmith Cougar390 Mitsubishi Zero180Piper J-3 Cub220 No Am P-Si Mustang170Rearwin Speedster270 Republic P-47180Stinson SR-8 Reliant280 Ryan PT-19190Taylorcaft BF-12-65220 Supermarine Spitfire130Waterman Gosling220 Appendix B understand better proper small tail size can determined given mode flying following table shows numerous items affect size Require Allow Larger Tail Area shorter tail-to-CG distance longer wingspan larger wing area shallower aft fuselage deeper forward fuselage larger prop diam pitch width0 longer prop-to-CG distance0 tractor prop larger wing aspect ratio smaller tail aspect ratio Tail forward aft stabilizer vertical tail shallower climb angle floating hinged rudder total effective dihedral high wing position faster trimmed airspeed Less no taper wing planform Require Allow Small Tail Area longer tail-to-CG distance shorter wingspan smaller wing area deeper aft fuselage shallower forward fuselage smaller prop diam pitch width shorter prop-f o-CG distance0 pusher prop smaller wing aspect ratio larger tail aspect ratio Tail over under stabilizer single vertical tail steeper climb angle Rudder fixed place Less total effective dihedral low wing position slower trimmed airspeed Less r no taper wing planform tractor prop vice-versa pusher prop Summary appears page 131 54 Model Aviation Modified Leading Edge fwiflProfileModified Aileron extended Stock Goldberg Eagle 63 Rib Profilea Unwin
Edition: Model Aviation - 1992/04
Page Numbers: 52, 53, 54
look correct problems EWilliam F McCombs PART ONE two-part article discussed combined influence vertical tail size total effective dihedral models stability flightand piloted airplanes influence vertical tail size in-flight controllability months conclusion explains adjust vertical tail size correct problems show up flight discusses achieve reasonable vertical tail area during design stage explains turning trim wing dihedral effective dihedral summary appendices included end article Tailoring tail two cases model has flown has troublesome other new unflown model 1 Existing troublesome modelProceed follows 2 below a If has trouble such wandering flight insensitivity small side thrust tail incidence changes mild severe Dutch roll glue small additional amount tail areaabout 5% existing areaand fly again Repeat necessary until trouble disappears b If has trouble such turning flight being very sensitive small side thrust tail incidence changes initial burst power Rubber models rendering incapable achieving steep climb because rolloff undesired spiraling simple solution same solution applies Free Flight Scale model will climb fly level because always spiraling down solution cut away little vertical tail areaabout 5% existing areaand fly again Repeat necessary until trouble disappears course must adequate minimum dihedral Free Flight Scale FFS model hinging rudder portion often adequate discussed 2 A new unflown modelThe procedure get approximately right size tail before flying avoid possible harm initial flights Start sheet balsa tail trim model good straight no turning slow hand-launched glide no stalling preferably good height standing table car longer glide better detect Dutch roll launch model its glide wing banked say left wing down about 400 properly launched model should quickly roll out its left bank glide straight turns right Dutch roll present Dutch roll the right turn glide long enough will turn left right etc shown Section la Part last month eliminate Dutch roll glue small amount tail area between successive glides Section la Part no Dutch roll seen cut away tail area small amountssay 5% existing areabetween successive glides until Dutch roll detected eliminate discussed above procedure will give very nearly right size tail beginning powered flights troubles section 1 shows up very small change tail area will eliminate sheet balsa tail can replaced built-up desired Rubber model prop doesnt freewbeel fold fix vertical position glide tests folds replace gliding very low powered straight level descending flights launching model wings banked suggested previously new FFS model another approach above rudder portion removed no very little Dutch roll model should alright rudder hinged float freely Dutch roll shows up later make horn area part fin still occurs increase fin area small amounts until disappears procedure will result smaller scale deviation can achieved using one-piece tail reducing entire tail area required per above tests particularly tail large floating rudder portion will also allow Old-Timer FF models large tails climb steeply desired About turning trim bad spiraling may course due bad trim rather spiral instability trim changes wont correct spiral instability 52 Model Aviation key optimal flight stability tailoring models vertical tail both during design stage after initial flight testing conclusion two-part article author tells what known cause Too much turning trim will cause tight turn too much banking spiral dive such tight turn wanted glide indoor flying wing warping used keep wing level usually done washinwarping trailing edge wing inside turn eg left wing left turn downward down aileron About 130 wing tip used depending upon turn tighter turn washin needed non-Scale Indoor models instead using wing warping wing usually offset slightly sideto left left turnabout 3-5% wingspan Using tilted stabilizer setting instead vertical tail rudder incidence produce gliding slow cruising turn preferred non-Scale models since effect essentially disappears during high-powered flight powered flight turn trimmed side thrust often fine-tuned small tail tab downthrust adjusted get desired upward climb model has trimmed turn direction using wing warping wing offset should made fly other direction will spiral crash unless wing warping wing offset removed high-powered steep-climbing FF Duration model launched flight must pointed steeply upward Otherwise will usually dive crash before can get its steep-climbing attitude Wing dihedral effective dihedral understand some PES models need wing dihedral others needs know about effective dihedral anything has same effect wing dihedral producing rolling effect whenever model sideslipie yawed attitude following main sources FFS models plus s good effect such dihedral minus - means negative effect such cathedral anhedral 1 Wing position high wing generates about 10 30 effective dihedral midwing generates low wing generates about 10 3O values typical nose forward fuselage sizes Scale models full-scale airplanes larger fatter nose greater effect vice-versa effect negligible Duration models have slim noses FFS models reasonable assume 20 high-wings 2o low-wings formula available see Appendix estimating closely 2 Wing tip shape As seen front view lower surface slants upward very abruptly meet upper surface about 1/20 effective dihedral generated upper surface slants downward meet lower surface about 2/20 generated both surfaces slant tip blunt rounded no effective dihedral generated values low-speed slow gliding slow cruising flight become less trimmed speed increases ie lift coefficient decreases 3 Wing aspect ratio wingspan age chord wingspan2 -i- wing area values approximately table below low-speed flight 2 above becoming smaller speed increases needed given model finds sum effective dihedral values 1 through 4 above subtracts sum 50 40 Indoor FFS models Outdoor FFS models doing gives wing dihedral 10 high-wings 30 midwings 50 low-wings 30 biplanes However relatively large vertical tail present small dihedral duration will suffer spiral instability may occur Either dihedral smaller tail will required prevent suggested glide test adequate minimum dihedral follows head height launched forward gliding speed wings banked about 400 model should roll out its banked attitude before landing Formula vertical tail area Although Wing Aspect Ratio 11/2221/2 331/244/o551/268 Effective Dihedral 370200 120 91/20 61/2040 31/2030 21/20 20 11/20 Note Dihedral needed during low-speed flight high-speed flight 4 Wing sweepback measured one-fourth-chord line values approximately table below forward sweep numbers negative values low-speed flight 2 3 above Sweepback Angle 00 100 200 300 400 450 Effective Dihedral 00 2 1/20 50 80 110 140 Therefore given FFS model total effective dihedral algebraic sum wing dihedral other effective dihedral may have lues above total effective dihedral just wing dihedral determines quickly model will return its trimmed attitude upset laterally banked gusty air example reasonably small tail model having 60 total dihedral will correct its attitude 60/120 half quickly has 120 Duration models have generous dihedral better duration large tail slows down recovery time hurting duration particularly total effective dihedral small FFS models Outdoor FFS models need about 50 total effective dihedral practical minimum gusty air Indoor models need about 40 always desirable better duration less crash damage risk greater scale deviation Therefore determine much wing dihedral proper small size tail can found flying previously discussed following formula will give fairly good estimate beginning flight tests AvNxAw xb/Lv where Av Verticaltailareainsqin Aw Wi ng area sq bWingspan inches Lv Distance inches CG aft center tail area N numerical factor given table below April 1992 53 Type FF ModelN Nordic class Glider006 Hand-Launched Glider015 Indoor Duration Microfilm018 Other Indoor Duration028 Gas-powered Duration023 Outdoor Rubber Duration033 Gas-powered Scale027 Rubber-powered Scale Speed035 above biplanes use formula below 1 means upper wing 2 means lower wing Av 9N [A1 x b1 b2] ther things being about equal low-wing model will found require smaller tail will high-wing model Sport fun models can have 1JL g These thirties-era Free Flight Gas models have taIls much too large todays standards generous dihedral unlike Scale models need climb steeply unlike Duration models hence need small tail required desired tail can two three times large Scale Duration planes small tail always preferable Scale model having generous dihedral really sport model ndix following formula can used estimate effective dihedral due wing position wing mounted cabane struts drLow Wing Effective dihedral* bA *in degrees area Depth fuselage station 1/3 distance between wings leading edge LE front nose block w h fuselage above station h htofwingsLE above below midpoint d above h w low wing h - hd use hd b Wingspan dimensions inches effective dihedral maximum ng mounted top bottom fuselage located above below fuselage using cabane struts resulting gap causes effective dihedral decrease Referring figure below can calculated Effective dihedral mum effective dihedral x 1 4gIb g between wing fuselage maximum effective dihedral lculated assuming wing located top bottom fuselage formula applies long gap no b/4 gCabana Struts gpIi Filling gap single piece thin clear plastic sheet leading edge trailing edge helps high-wing giving effective dihedral per first formula following table shows calculated effective dihedral due wing position several representative airplanes Table A-i Effective Dihedral due Wing Position AirplaneDihedral AirplaneDihedral Aeronca LB LC-1 20Vought F4U Corsair2 50 Bell P-39 Airacobra240Vought V-143210 Curtiss P-40 Warhawk150Bede B0-4350 Focke-Wuif Ta 152130Corben Super Ace230 Davis DA-2Aj70Curtiss Robin150 Grumman F6F Hellcat140Fairchild 2425 Hawker Hurricane120Howard Mr Mulligan4Q0 Heinkel 1000-11Lockheed Vega240 Jodel 0-9 JoMonocoupe 90A240 Messerschmitt Bf 109e180Nesmith Cougar390 Mitsubishi Zero180Piper J-3 Cub220 No Am P-Si Mustang170Rearwin Speedster270 Republic P-47180Stinson SR-8 Reliant280 Ryan PT-19190Taylorcaft BF-12-65220 Supermarine Spitfire130Waterman Gosling220 Appendix B understand better proper small tail size can determined given mode flying following table shows numerous items affect size Require Allow Larger Tail Area shorter tail-to-CG distance longer wingspan larger wing area shallower aft fuselage deeper forward fuselage larger prop diam pitch width0 longer prop-to-CG distance0 tractor prop larger wing aspect ratio smaller tail aspect ratio Tail forward aft stabilizer vertical tail shallower climb angle floating hinged rudder total effective dihedral high wing position faster trimmed airspeed Less no taper wing planform Require Allow Small Tail Area longer tail-to-CG distance shorter wingspan smaller wing area deeper aft fuselage shallower forward fuselage smaller prop diam pitch width shorter prop-f o-CG distance0 pusher prop smaller wing aspect ratio larger tail aspect ratio Tail over under stabilizer single vertical tail steeper climb angle Rudder fixed place Less total effective dihedral low wing position slower trimmed airspeed Less r no taper wing planform tractor prop vice-versa pusher prop Summary appears page 131 54 Model Aviation Modified Leading Edge fwiflProfileModified Aileron extended Stock Goldberg Eagle 63 Rib Profilea Unwin
Edition: Model Aviation - 1992/04
Page Numbers: 52, 53, 54
look correct problems EWilliam F McCombs PART ONE two-part article discussed combined influence vertical tail size total effective dihedral models stability flightand piloted airplanes influence vertical tail size in-flight controllability months conclusion explains adjust vertical tail size correct problems show up flight discusses achieve reasonable vertical tail area during design stage explains turning trim wing dihedral effective dihedral summary appendices included end article Tailoring tail two cases model has flown has troublesome other new unflown model 1 Existing troublesome modelProceed follows 2 below a If has trouble such wandering flight insensitivity small side thrust tail incidence changes mild severe Dutch roll glue small additional amount tail areaabout 5% existing areaand fly again Repeat necessary until trouble disappears b If has trouble such turning flight being very sensitive small side thrust tail incidence changes initial burst power Rubber models rendering incapable achieving steep climb because rolloff undesired spiraling simple solution same solution applies Free Flight Scale model will climb fly level because always spiraling down solution cut away little vertical tail areaabout 5% existing areaand fly again Repeat necessary until trouble disappears course must adequate minimum dihedral Free Flight Scale FFS model hinging rudder portion often adequate discussed 2 A new unflown modelThe procedure get approximately right size tail before flying avoid possible harm initial flights Start sheet balsa tail trim model good straight no turning slow hand-launched glide no stalling preferably good height standing table car longer glide better detect Dutch roll launch model its glide wing banked say left wing down about 400 properly launched model should quickly roll out its left bank glide straight turns right Dutch roll present Dutch roll the right turn glide long enough will turn left right etc shown Section la Part last month eliminate Dutch roll glue small amount tail area between successive glides Section la Part no Dutch roll seen cut away tail area small amountssay 5% existing areabetween successive glides until Dutch roll detected eliminate discussed above procedure will give very nearly right size tail beginning powered flights troubles section 1 shows up very small change tail area will eliminate sheet balsa tail can replaced built-up desired Rubber model prop doesnt freewbeel fold fix vertical position glide tests folds replace gliding very low powered straight level descending flights launching model wings banked suggested previously new FFS model another approach above rudder portion removed no very little Dutch roll model should alright rudder hinged float freely Dutch roll shows up later make horn area part fin still occurs increase fin area small amounts until disappears procedure will result smaller scale deviation can achieved using one-piece tail reducing entire tail area required per above tests particularly tail large floating rudder portion will also allow Old-Timer FF models large tails climb steeply desired About turning trim bad spiraling may course due bad trim rather spiral instability trim changes wont correct spiral instability 52 Model Aviation key optimal flight stability tailoring models vertical tail both during design stage after initial flight testing conclusion two-part article author tells what known cause Too much turning trim will cause tight turn too much banking spiral dive such tight turn wanted glide indoor flying wing warping used keep wing level usually done washinwarping trailing edge wing inside turn eg left wing left turn downward down aileron About 130 wing tip used depending upon turn tighter turn washin needed non-Scale Indoor models instead using wing warping wing usually offset slightly sideto left left turnabout 3-5% wingspan Using tilted stabilizer setting instead vertical tail rudder incidence produce gliding slow cruising turn preferred non-Scale models since effect essentially disappears during high-powered flight powered flight turn trimmed side thrust often fine-tuned small tail tab downthrust adjusted get desired upward climb model has trimmed turn direction using wing warping wing offset should made fly other direction will spiral crash unless wing warping wing offset removed high-powered steep-climbing FF Duration model launched flight must pointed steeply upward Otherwise will usually dive crash before can get its steep-climbing attitude Wing dihedral effective dihedral understand some PES models need wing dihedral others needs know about effective dihedral anything has same effect wing dihedral producing rolling effect whenever model sideslipie yawed attitude following main sources FFS models plus s good effect such dihedral minus - means negative effect such cathedral anhedral 1 Wing position high wing generates about 10 30 effective dihedral midwing generates low wing generates about 10 3O values typical nose forward fuselage sizes Scale models full-scale airplanes larger fatter nose greater effect vice-versa effect negligible Duration models have slim noses FFS models reasonable assume 20 high-wings 2o low-wings formula available see Appendix estimating closely 2 Wing tip shape As seen front view lower surface slants upward very abruptly meet upper surface about 1/20 effective dihedral generated upper surface slants downward meet lower surface about 2/20 generated both surfaces slant tip blunt rounded no effective dihedral generated values low-speed slow gliding slow cruising flight become less trimmed speed increases ie lift coefficient decreases 3 Wing aspect ratio wingspan age chord wingspan2 -i- wing area values approximately table below low-speed flight 2 above becoming smaller speed increases needed given model finds sum effective dihedral values 1 through 4 above subtracts sum 50 40 Indoor FFS models Outdoor FFS models doing gives wing dihedral 10 high-wings 30 midwings 50 low-wings 30 biplanes However relatively large vertical tail present small dihedral duration will suffer spiral instability may occur Either dihedral smaller tail will required prevent suggested glide test adequate minimum dihedral follows head height launched forward gliding speed wings banked about 400 model should roll out its banked attitude before landing Formula vertical tail area Although Wing Aspect Ratio 11/2221/2 331/244/o551/268 Effective Dihedral 370200 120 91/20 61/2040 31/2030 21/20 20 11/20 Note Dihedral needed during low-speed flight high-speed flight 4 Wing sweepback measured one-fourth-chord line values approximately table below forward sweep numbers negative values low-speed flight 2 3 above Sweepback Angle 00 100 200 300 400 450 Effective Dihedral 00 2 1/20 50 80 110 140 Therefore given FFS model total effective dihedral algebraic sum wing dihedral other effective dihedral may have lues above total effective dihedral just wing dihedral determines quickly model will return its trimmed attitude upset laterally banked gusty air example reasonably small tail model having 60 total dihedral will correct its attitude 60/120 half quickly has 120 Duration models have generous dihedral better duration large tail slows down recovery time hurting duration particularly total effective dihedral small FFS models Outdoor FFS models need about 50 total effective dihedral practical minimum gusty air Indoor models need about 40 always desirable better duration less crash damage risk greater scale deviation Therefore determine much wing dihedral proper small size tail can found flying previously discussed following formula will give fairly good estimate beginning flight tests AvNxAw xb/Lv where Av Verticaltailareainsqin Aw Wi ng area sq bWingspan inches Lv Distance inches CG aft center tail area N numerical factor given table below April 1992 53 Type FF ModelN Nordic class Glider006 Hand-Launched Glider015 Indoor Duration Microfilm018 Other Indoor Duration028 Gas-powered Duration023 Outdoor Rubber Duration033 Gas-powered Scale027 Rubber-powered Scale Speed035 above biplanes use formula below 1 means upper wing 2 means lower wing Av 9N [A1 x b1 b2] ther things being about equal low-wing model will found require smaller tail will high-wing model Sport fun models can have 1JL g These thirties-era Free Flight Gas models have taIls much too large todays standards generous dihedral unlike Scale models need climb steeply unlike Duration models hence need small tail required desired tail can two three times large Scale Duration planes small tail always preferable Scale model having generous dihedral really sport model ndix following formula can used estimate effective dihedral due wing position wing mounted cabane struts drLow Wing Effective dihedral* bA *in degrees area Depth fuselage station 1/3 distance between wings leading edge LE front nose block w h fuselage above station h htofwingsLE above below midpoint d above h w low wing h - hd use hd b Wingspan dimensions inches effective dihedral maximum ng mounted top bottom fuselage located above below fuselage using cabane struts resulting gap causes effective dihedral decrease Referring figure below can calculated Effective dihedral mum effective dihedral x 1 4gIb g between wing fuselage maximum effective dihedral lculated assuming wing located top bottom fuselage formula applies long gap no b/4 gCabana Struts gpIi Filling gap single piece thin clear plastic sheet leading edge trailing edge helps high-wing giving effective dihedral per first formula following table shows calculated effective dihedral due wing position several representative airplanes Table A-i Effective Dihedral due Wing Position AirplaneDihedral AirplaneDihedral Aeronca LB LC-1 20Vought F4U Corsair2 50 Bell P-39 Airacobra240Vought V-143210 Curtiss P-40 Warhawk150Bede B0-4350 Focke-Wuif Ta 152130Corben Super Ace230 Davis DA-2Aj70Curtiss Robin150 Grumman F6F Hellcat140Fairchild 2425 Hawker Hurricane120Howard Mr Mulligan4Q0 Heinkel 1000-11Lockheed Vega240 Jodel 0-9 JoMonocoupe 90A240 Messerschmitt Bf 109e180Nesmith Cougar390 Mitsubishi Zero180Piper J-3 Cub220 No Am P-Si Mustang170Rearwin Speedster270 Republic P-47180Stinson SR-8 Reliant280 Ryan PT-19190Taylorcaft BF-12-65220 Supermarine Spitfire130Waterman Gosling220 Appendix B understand better proper small tail size can determined given mode flying following table shows numerous items affect size Require Allow Larger Tail Area shorter tail-to-CG distance longer wingspan larger wing area shallower aft fuselage deeper forward fuselage larger prop diam pitch width0 longer prop-to-CG distance0 tractor prop larger wing aspect ratio smaller tail aspect ratio Tail forward aft stabilizer vertical tail shallower climb angle floating hinged rudder total effective dihedral high wing position faster trimmed airspeed Less no taper wing planform Require Allow Small Tail Area longer tail-to-CG distance shorter wingspan smaller wing area deeper aft fuselage shallower forward fuselage smaller prop diam pitch width shorter prop-f o-CG distance0 pusher prop smaller wing aspect ratio larger tail aspect ratio Tail over under stabilizer single vertical tail steeper climb angle Rudder fixed place Less total effective dihedral low wing position slower trimmed airspeed Less r no taper wing planform tractor prop vice-versa pusher prop Summary appears page 131 54 Model Aviation Modified Leading Edge fwiflProfileModified Aileron extended Stock Goldberg Eagle 63 Rib Profilea Unwin