Free Flight Indoor Bud Tenny Na special tail Dick Hardcaatles mag nificent D slight accident Chilton pix Indoor Props Indoor duration models al kind free-flight model use depend prop whole flight small wonder indoor prop con sidered almost important part model poor prop will hold model back whole flight What makes bad prop hard define since particular prop may good model almost disaster another model best can ex amine factors learn select best prop model Prop Pitch measurement distance prop pulls model through air revolution related blade angle Think machine screw turning its nutthe pitch screw given threads per inch 40 threads per inch screw moves 1/40 inch per revolution Propellers have called airscrews ob vious reasons similar measurement can made propeller distance model moves forward revolution prop called effective pitch reason distinction made because air isnt solid like nut props slip little revolu tion effective pitch lower design pitch design pitch what people talk about regard props usually set shape prop block jig used build prop Prop Blocks years now almost props have built carved wood blocks like shown Fig 1 blocks usually carved balsa design mula shown Fig 1 Since design pitch related dimensions carved part block should possible check prop blade later see has warped 314 cOsT w formula Fig can changed noted T/W tangent remember trigo nometry angle end block Similarly T/W tangent angle shown middle block Using new formula Pitch X Dia X tan blade angle possible check pitch unknown prop check old prop warps simple fixture can made measure blade angle during field repairsvery handy Block Carving Hints people carv ing prop blocks bug-a-boo isnt hard maybe hints will help I Dont make block too small Start least l0-long block unless never plan make model larger Easy B pitch prop same block no matter long can build 15 X 30 prop well 20 X 30 prop same 30 pitch block 2 Design 28 32 pitch 30 pitch usu ally works very well models wing spans between 20 30 3 sure make block wide enough block should least 4 wide 20 diameter propswhich means block would also need about 2 thick block less 3 wide begin probably wont enough room near hub end block suitably wide blade 4 Lay Out dimensions carved area balsa block marker pen work very carefully working surface block must very flat after carving finished plan carve sandpaper alternately since grit sandpaper will catch wood ruin blade Carve very close proper shape very sharp knife removing very thin layers Get surface flat possible sandpaper final shape Prop Building After carving finished draw blade outline rib locations block Fig 2 gives idea would look Fig 2 also shows two important things about prop construction First prop spar hook assembled before prop blades begun Second spar laid block hook exactly vertical edge block hook must exactly vertical hook isnt end block two blades will different length hook isnt vertical blade angles will different Either way prop guaranteed wobble What Size Prop used indoor fliers used 50% wing span good diameter prop recent years has creased 60% 65% microfilm models 1972 Indoor World Champion Pete Andrews first begin using 20 props FAI models 65cm 254 wing span 74% wing span csn t topPete test-flew FAI models 24 props 1974 Indoor World Cham pionships prop 94% wing span boggles mind consider PennyPlane quickly found PennyPlanes flew better rubber rubber up about 1 s bare model weight makes models fly better Since PennyPlanes heavy need lot rubber Lately has common PennyPlane props about 95% wing span times have nearly doubled logged earlier PennyPlanes Basically heavy model lots rubber needs large propsometimes much larger same design built very lightlyif good times expected Prop pitch also cru continued page 73 UI Fig 2 September 1975 21 Bill Fuoris Quarter Midget continued page 10 X ply glued groove pro tect edges surfaces surfaces can sanded shape shown plans elevators lower portion rudder cut off hinged rudder stab epoxied fuselage canopy added making certain minimum fuselage height S maintained Fillets stalled wing tail canopy cowls using microballoons wheel pants now constructed entire airplane final sanded suggested aluminum landing gear struts filed airfoil shape particu larly leading edge fuselage rudder wheel pants should now given coat resin coat epoxy filler sanding after fuse lage given light coat epoxy paint wing stab should covered Monokote Solar Film Equipment I have found coupled aileron rudder works fine problems Therefore necessary have two servos within fuselage aileron/rudder elevator engine servo mounted tank compartment right side fuselage proper balance receiver battery pack should mounted against former 2 tank four oz Sullivan slant type Flying The airplane will prove responsive stable adhere CG location control surface deflec tions indicated plan find set up will turn dime slightest snap roll tendency tight est turns will cause no structural damage all-up weight model does exceed 3 pounds However plane weighs would suggest whip smoothly gently turn pylon five ships Ive built still existence ranged weight 40 oz 42 oz Well guess thats about rest up engine radio FF Indoor continued page 21 cial everyone agrees much pitch too much important thing have enough pitch Luckily fairly easy determine prop pitch too low particular model Simply measure rpm just after model stops climbing As general rule properly adjusted microfilm model heavy should have cruise rpm tween 45 55 Lighter models will should have lower range rpm Measure RPM Indoor props except PennyPlane Easy B usually turn slower han 80 rpm some go low 35 rpm rhat can see prop turning common method measuring rpm time long takes prop make 10 revolu tions 9egin count 0 start watch count next time same blade comes up count other blade continue 10 Count 10 just blade passes start position 10th time Divide time seconds 600 get rpm example 8 seconds 10 revs 600/8 75 rpm Thats too high Strive 12 seconds 48 rpm 15 seconds 40 rpm Sad True reporter has never able understand indoor activity around country comes halt sum mer During warm weather models fly bet ter rubber works better rubber output proportional temperature always easier handle fragile models warm hands Nonetheless Miami Fla modelers fly indoor blimp hangers Lakehurst NJ have summer activity Miami fliers have about 10 months activity year hangars have good conditions during summer address P0 Box 545 Richardson Texas 75080 September1975 73 EOW*15005U15I5 p.idI July 1975 Dear Fellow Model Nuilders hope building leaet thoce beautiful sew Kite Flying Fortress Kingfish Gavela Prineiro now available tobby Shop way. 1/2 Nylon Anoennorien also releaaed new Kits havent seen sure oheok dealer Theyre great gain 575 end will good job Knerythiog in psohage Nylon Motor Mouot control Morn Mell Crank Nuts & Molts easy installation told about new s/C Stinson Reliant 40 engines last letter Digineering Depart ment going full speed ahead projent deliver Kits sometime Fell Im sure saw writeup Goosriator N/C Modeler know youll enjoy building flying one. want take opportunity eotend ny ninoere thanks eath emery helping make doys brighter during pant several weeks have hoes sonvelesoing surgery thoughtful reaseheronoen nnd good wishes will long remembered Weve enjoyed letters appretiete suggestions. Keop cOming 3620 G StreetPhiladelphia Pennsylvania 19134USA produotrevinswnrnd urtrao imwnnductaoieworoduttreoisw Sanding Blocks Ideal sanding large areas such wings stabs fuselages etc new sanding blocks have high-quality 3M open coat sandpaper bonded high-density foam block Available three grits size 9 x 3-3/4 89 cents Prather Products 1660 Ravenna Ave. Wilming ton Ca 90744 Tricks tradethe bent fuselage design Stan Chilton gives model high thrust line prodwctaoiewprodwcOeoiewPodwctrCoiCWPrOdwCtrCoiCW otherwise normal layout Other structural details show up clearly
Edition: Model Aviation - 1975/09
Page Numbers: 21, 73
Free Flight Indoor Bud Tenny Na special tail Dick Hardcaatles mag nificent D slight accident Chilton pix Indoor Props Indoor duration models al kind free-flight model use depend prop whole flight small wonder indoor prop con sidered almost important part model poor prop will hold model back whole flight What makes bad prop hard define since particular prop may good model almost disaster another model best can ex amine factors learn select best prop model Prop Pitch measurement distance prop pulls model through air revolution related blade angle Think machine screw turning its nutthe pitch screw given threads per inch 40 threads per inch screw moves 1/40 inch per revolution Propellers have called airscrews ob vious reasons similar measurement can made propeller distance model moves forward revolution prop called effective pitch reason distinction made because air isnt solid like nut props slip little revolu tion effective pitch lower design pitch design pitch what people talk about regard props usually set shape prop block jig used build prop Prop Blocks years now almost props have built carved wood blocks like shown Fig 1 blocks usually carved balsa design mula shown Fig 1 Since design pitch related dimensions carved part block should possible check prop blade later see has warped 314 cOsT w formula Fig can changed noted T/W tangent remember trigo nometry angle end block Similarly T/W tangent angle shown middle block Using new formula Pitch X Dia X tan blade angle possible check pitch unknown prop check old prop warps simple fixture can made measure blade angle during field repairsvery handy Block Carving Hints people carv ing prop blocks bug-a-boo isnt hard maybe hints will help I Dont make block too small Start least l0-long block unless never plan make model larger Easy B pitch prop same block no matter long can build 15 X 30 prop well 20 X 30 prop same 30 pitch block 2 Design 28 32 pitch 30 pitch usu ally works very well models wing spans between 20 30 3 sure make block wide enough block should least 4 wide 20 diameter propswhich means block would also need about 2 thick block less 3 wide begin probably wont enough room near hub end block suitably wide blade 4 Lay Out dimensions carved area balsa block marker pen work very carefully working surface block must very flat after carving finished plan carve sandpaper alternately since grit sandpaper will catch wood ruin blade Carve very close proper shape very sharp knife removing very thin layers Get surface flat possible sandpaper final shape Prop Building After carving finished draw blade outline rib locations block Fig 2 gives idea would look Fig 2 also shows two important things about prop construction First prop spar hook assembled before prop blades begun Second spar laid block hook exactly vertical edge block hook must exactly vertical hook isnt end block two blades will different length hook isnt vertical blade angles will different Either way prop guaranteed wobble What Size Prop used indoor fliers used 50% wing span good diameter prop recent years has creased 60% 65% microfilm models 1972 Indoor World Champion Pete Andrews first begin using 20 props FAI models 65cm 254 wing span 74% wing span csn t topPete test-flew FAI models 24 props 1974 Indoor World Cham pionships prop 94% wing span boggles mind consider PennyPlane quickly found PennyPlanes flew better rubber rubber up about 1 s bare model weight makes models fly better Since PennyPlanes heavy need lot rubber Lately has common PennyPlane props about 95% wing span times have nearly doubled logged earlier PennyPlanes Basically heavy model lots rubber needs large propsometimes much larger same design built very lightlyif good times expected Prop pitch also cru continued page 73 UI Fig 2 September 1975 21 Bill Fuoris Quarter Midget continued page 10 X ply glued groove pro tect edges surfaces surfaces can sanded shape shown plans elevators lower portion rudder cut off hinged rudder stab epoxied fuselage canopy added making certain minimum fuselage height S maintained Fillets stalled wing tail canopy cowls using microballoons wheel pants now constructed entire airplane final sanded suggested aluminum landing gear struts filed airfoil shape particu larly leading edge fuselage rudder wheel pants should now given coat resin coat epoxy filler sanding after fuse lage given light coat epoxy paint wing stab should covered Monokote Solar Film Equipment I have found coupled aileron rudder works fine problems Therefore necessary have two servos within fuselage aileron/rudder elevator engine servo mounted tank compartment right side fuselage proper balance receiver battery pack should mounted against former 2 tank four oz Sullivan slant type Flying The airplane will prove responsive stable adhere CG location control surface deflec tions indicated plan find set up will turn dime slightest snap roll tendency tight est turns will cause no structural damage all-up weight model does exceed 3 pounds However plane weighs would suggest whip smoothly gently turn pylon five ships Ive built still existence ranged weight 40 oz 42 oz Well guess thats about rest up engine radio FF Indoor continued page 21 cial everyone agrees much pitch too much important thing have enough pitch Luckily fairly easy determine prop pitch too low particular model Simply measure rpm just after model stops climbing As general rule properly adjusted microfilm model heavy should have cruise rpm tween 45 55 Lighter models will should have lower range rpm Measure RPM Indoor props except PennyPlane Easy B usually turn slower han 80 rpm some go low 35 rpm rhat can see prop turning common method measuring rpm time long takes prop make 10 revolu tions 9egin count 0 start watch count next time same blade comes up count other blade continue 10 Count 10 just blade passes start position 10th time Divide time seconds 600 get rpm example 8 seconds 10 revs 600/8 75 rpm Thats too high Strive 12 seconds 48 rpm 15 seconds 40 rpm Sad True reporter has never able understand indoor activity around country comes halt sum mer During warm weather models fly bet ter rubber works better rubber output proportional temperature always easier handle fragile models warm hands Nonetheless Miami Fla modelers fly indoor blimp hangers Lakehurst NJ have summer activity Miami fliers have about 10 months activity year hangars have good conditions during summer address P0 Box 545 Richardson Texas 75080 September1975 73 EOW*15005U15I5 p.idI July 1975 Dear Fellow Model Nuilders hope building leaet thoce beautiful sew Kite Flying Fortress Kingfish Gavela Prineiro now available tobby Shop way. 1/2 Nylon Anoennorien also releaaed new Kits havent seen sure oheok dealer Theyre great gain 575 end will good job Knerythiog in psohage Nylon Motor Mouot control Morn Mell Crank Nuts & Molts easy installation told about new s/C Stinson Reliant 40 engines last letter Digineering Depart ment going full speed ahead projent deliver Kits sometime Fell Im sure saw writeup Goosriator N/C Modeler know youll enjoy building flying one. want take opportunity eotend ny ninoere thanks eath emery helping make doys brighter during pant several weeks have hoes sonvelesoing surgery thoughtful reaseheronoen nnd good wishes will long remembered Weve enjoyed letters appretiete suggestions. Keop cOming 3620 G StreetPhiladelphia Pennsylvania 19134USA produotrevinswnrnd urtrao imwnnductaoieworoduttreoisw Sanding Blocks Ideal sanding large areas such wings stabs fuselages etc new sanding blocks have high-quality 3M open coat sandpaper bonded high-density foam block Available three grits size 9 x 3-3/4 89 cents Prather Products 1660 Ravenna Ave. Wilming ton Ca 90744 Tricks tradethe bent fuselage design Stan Chilton gives model high thrust line prodwctaoiewprodwcOeoiewPodwctrCoiCWPrOdwCtrCoiCW otherwise normal layout Other structural details show up clearly