TWO MONTHS AGO wrote about locating proper center-of-gravity conventional air plane Last month extended cover canard airplanes flying wing airplanes sat back thinking subject done addition requests formation mail bag has full lots good questions Rather sending answers questioners decided include better questions answer questions related wings did have straight leading trailing edges good example sent Bob Hanson Colo rado Springs CO former club mem ber president club Eglin Aero Model lers Bob working Sport Scale Fairchild A-b wanted know apply equa tions Id published earlier A-b wing looks something like Figure 1 will note center section wing rectangular outboard sections swept tapered type wing stabilizer uncom mon decided show calculate ap propriate aerodynamic centers proper centerof-gravity case Several writers have com mented use two integral equations July column daring because mag azine editors assume readers education stopped fifth grade dont think thats true what am attempt may put strain some readers backgrounds take close look area aerody namic center equations youll see can broken pieces example area equa tion shown Equation 6 can split pans B125/2 65dA First since wing symmetric about center integration can performed center wing tip answer doubled get area deal ing wing Figure 1 integration can performed separately over two pieces half wing result shown Equation 7 b/25/2 7 5 2jcidy c2dy Rb Bb/2 R w comes tough part Similar arguments can done aerodynamic center calcula tions consider symmetry investigate wing like Figure 1 youll get result shown Equation 8 b/2 8 X ifS [2jxicidY Figure 1 0 B F Rons back fInd-the-center-of-gravity mode again month time well learn find proper CG wings odd shapes such examples Read Figure 2 52 2f x2c2dy l/S{R14 Rb [l/6 R2 T2 RT D/3 R [Bb/2 R RT Note now 1/S term front equation missing original tegral equation presented July issue Lets look what have Equation 8 R/4 term location aerodynamic cen ter rectangular portion wing would calculated treated wing U 0 ac 0 &c itself Similarly long term square brackets [ ] location aerodynamic center trapezoidal portion wing youd get treated wing itself aerodynamic center location dis tances multiplied area its respective part wing after two added whole thing divided total wing area can simplify Equation 8 Equation 9 Xl X2 SI S2 aerodynamic center location distances areas two pieces wing 9 X S eads great generalization because can easily calculate aerodynamic center complicated wing stacking up spanwise pieces wing would handle wing like Fig ure 2 can use basic equations area aerodynamic center can simple sum division Equation 10 10 X x353 S S3 complicating factor using Equation 10 X distances Xl X2 X3 must same point example leading edge root chord wing shown Once youve determined location wing aerodynamic center can same thing horizontal tail use same center-of-gravity equation gave July issue save trouble having dig out July issue Im repeating equation Equation 3here 3 CG Stab Area 3 x Wing Area R2 T2 15R Admittedly probably some have no desire calculate proper centerof-gravity location airplane youre probably bored out skull now Ill quit subject move other things benefits writing column 44 Model Aviation Radio Control Sport Aerobatics Ron Van Putte III Sleepy Oaks Rd Ft Walton Beach FL 32548 Heyl did Van Putte put two aileron ser vos airplane Text has story get report personal experiences re late RC real heart-stopper last night went out flying field after work wait summertime thundershower quit before getting chance fly time stopped raining sun low sky overcast needed work out some system kinks before contest weekend fueled up airplane took off despite approaching darkness Five minutes flight rolled air plane inverted Reverse Cuban Eight didnt stop rolling assumed aileron servo failed put opposite aileron control stopped roll though could see airplane silhouette able nurse airplane bumpy safe landing Sure enough aileron servo failed able save airplane because has two aile ron servos aileron also have two elevator servos elevator Obviously purpose second servo give chance save airplane case quits worked fine figure extra servo weighs about 1 /2 oz can toler ate three ounces extra two servos add weight airplane What does two ex tra servos cost lot less new airplane/ engine/radio End sermon What would like see write about column would glad hear Two modelers did let know Frank Prestwood Valparaiso FL suggested write about servo torque requirements proper choice servos can made Good idea years ago Kraft Systems came out KPS-12 servo tiny jewel compared other servos yesteryear Its small compared todays servos Pat tern fliers put KPS-12 servos 100-mph ships performed adequately memory serves output torque KPS 12 servo 17-19 inch-ounces case doesnt mean anything average servo being sold today has output torque 35-45 inchounces Does mean KPS- 12 inadequate 100-mph Pattern ships Probably price pay inadequate servo torque re duced airplane responsiveness strong fast servo starts stops maneuvers crisply low-torque servo weak servo can suffer control surface blowback example perform loop higher speed backside loop puts higher load elevator servo may able resist load elevator will ac tually blow back smaller deflection angle means might enough eleva tor deflection pull airplane through bot tom loop Nobody likes loops end up looking like Figure Nines Now above discussion doesnt help deciding what servo use particular applica tion So what intend make some com putations will enable flier use some rule-of-thumb procedures application Ob viously procedures will have consider such variables airplane maneuver air speed control horn lengths servo-arm size like will take some time right So plan seeing column issue right af ter Nats report other suggested topics came Ralph Grose Riverside CA Ralph wants discussion what lift distribution looks like wing showing effects different wing shapes Continued page 134 DISTRIBUTED BY SMITh END ff815558 7555 5xr Gxbnel Soxd cdro CA 93422 4561717 Classic Glass Grumman Wildcat KIT FEATURES Polyester fiberglass fusalage cowling retractable landing 92 wingspan gear Foam cores wing stab Available major production variations F4F-3 -3A -4 FM-i FM-2 Semi-Kit Fusalage cowling foam cores wing $27500 stab canopy retractable landing gear plans Complete Kit Everything listed semi-kit plus wood parts hardware necessary complete kit including 1/64 plywood sheeting wings $45000 Deluxe Kit Complete kit fusalage preassembled $85000 wings stab presheeted control surfaces prebuilt add $1500 shipping Information Package $100 /MasterCard acceptedIdaho res add 5% sales rex Mike Zamber Classic Glass PO Box 503 Blackfoot Idaho 83221-0503 85-2309 September 1988 45 $975AVAILABLE AT AMERICAS$525 FINEST HOBBY SHOPS Carbon Fiber Laminates Aerospace Composite Products offers variety rigid carbon fiber epoxy sheets add stiffness almost material- fiberglass foam baisawood laminates can used reinforce foam wings leading trailing edges wing spars Carbon Fiber bonds easily slow setting cyanoacrylates 5-Minute epoxies laminate can stripped narrower widths CL-i007thick1x36-$4001x48-$500Px72-$700 CL-2 014 thick Vx36- $700 Px48- $800 Px72- $1100 CL-3 022 thick 1x36 $900 Px48- $1100 1x72- $1500 CL-4 OSOlhick Px36-$1100 Px48- $1400 Px72- $1800 Send SASE information additional sizes products Add $300 shipping handling Calif Residents add 6% tax Overseas orders add 15%- Order COD send check money order Aerospace Composite Products PO Box 16621 Irvine CA 92714- 714 250-1107 Source LightweIght Materials 115 Scale Z2ZtWincheEZ NEW SPACE SAVING CONTAINER FitsinYourBox 2Ax7%highx9% Tough Rigid Polyethylene udes Tubing eners Lock Tubing Through Cap ostage North Products PO Box 18419 Cleveland Heights OH 44118 II'I pack balanced cell shorted probably makes sense replace bad cell pair cells thats way packaged As can see pictures cells Kraft synthesizer transmitter packaged pairs replaced whole pack need transmitter Myers/Aberle tests want best contact friend Larry Sribnick SR Batteries Box 287 Bellport NY 11713 516 286-0079 SR can will supply packs connectors equipment manufactured Ace RJC Airtronics Cannon Cirrus Cox/Sanwa Futaba Kraft Tower some World Engines anything Deans con nector cant find source manufacturers connector can always use Deans Connectors Ace R/C see above contact SR help As example havent able find source Hi-Tee connec tor used Polks World Engines use Deans As cells themselves SR will suggest al ternatives like SR900s will fit place SOOs will make up packs special configu rations number cells L shapes stacked packs etc keep up-todate file original transmitter battery pack con figurations can make up literally pack need Though dont like doing SR will re place individual cells pack chafg ing $2 over cost materials giving pack full five-day test sequence insure worthy continued use Some manufacturers make battery pack replace ment simple plug-in matter Airtronlcs others make take apart transmitter af fair case Kraft faced latter situation least bit hesitant about making change turn prob lem over serviceman Check warranty first Im still vacation Happy flying Noise/Weiss Continued page 43 D Always build maintain air craft ensure minimum vibration levels Sounds vibrating pushrods loose fit tings loose coverings less-than-solid airframes contribute noise lot room research experimenta tion engine-mounting techniques related structural considerations E Last least some minor per formance compromises will sometimes necessary keep flying sites will ing accept open mind Once get familiar terms quieter aircraft will actually enjoy results effort Conclusions todays world us have no choice sound process model aircraft Much research work experimentation remain done little know right now can go long way toward reducing noise keeping flying fields hope manufacturers will get involved future since too have lot stake technology us today success depends applying specific problems Future research experimentation may provide bet ter methods meet lower sound objec tives have gratified other fliers club geographic area have shown greater awareness need fly quietlyand increasing interest involvement achieving goal breaking old habits developing new ones may find enjoy hobby past will really appreciate quieter models flight line Ive shared above information order fill needa need ef fective simple starting point embark upon sound proces sing approach quiet flight predict will new information new prod ucts appearing increasing rate meantime invest some time effort have fun above keep em flying RC AerobaticsNan Putte Continued page 45 Hed also like read about what expect bending moment center wing Obvi ously both topics tied together Ill work soon can Any other ideas RC Slope Soaring/Triebes Continued page 47 art system indispensable some competitive thermal flying and/or F3B As investing much money system really get what pay have inten tions continuing sport years come will undoubtedly run need such capabilities future true other things might well get best possible radio system can afford recently received letter Pierre Dume nil expressed very interesting idea malting videotape Slope Soaring finlshed will available clubs area would like get people involved Slope Soaring tape will great way show just what facet Soaring about Most people reluctant get involved something havent seen great way get Slope Soaring expo sure deserves talk Pierre sounds video going very highquality production shows aspects Slope Soaring youd like get copy videotape should available very soon just let know will pass word Pierre would like mention again will International Slope Race F3F Denmark sometime 1989 Anyone interested going either spectator competitor should get touch soon possible looks like will truly incredible event have urge go would highly rec ommend would really like thank whove sent letters and/or called response writings Slope Soaring response has greater ever imagined love help will able bring Slope Soaring forefront RC Soaring So keep letters photos calls coming 134 Model Aviation LiqIii LINE SYSTEMS P0 Box 1502 Lewiston 04241 FOAM CORE FLOATS PLANS AND KITS WE OFFER SELECTION OF FLOAT PLANS AND KITS FOR 4 12 POUND AIRPLANES WITH Y HULL ESIGN IN USE SINCE 1972 SEND SASE FOR CATALOG SHEET KIRCHER R/C PRODUCTS [NC 9 SHEFFIELD WAY CLARK NJ 07066 i A WE BUILD YOUR HELl TEST YOUR HELl PAIR YOUR HELl 322 North 7th St 64$ V11 Lehighton Pa 18235 WRITE OR CALL FOR INFORMA TION WOAL55 SOO5ST SCALP PHOtO SESVCP 500 PHOTO PACKS PLANS 3 VIEWS PHOTO-PACKS PLANS ENLARGING S*SE EnISr5O5 COPS lip Pepin&s Catalog $oo 60 pagesSCALE PlANS Eli PHOTO SERVICE 3209 Madsoo GeensOooo N C 27403 Phoop lnIal2a25239 INs ColleCt 77T L4TNES MILS lIETALS B00S PRECISI0N ISJSTR.MENTS - - CClIPFTE CAI$00 $200 IOn 8 SeIonR2 Sprngfo12 O8~ 43505 mpa 513 3220562 PAWU DIESELS Englands Finest 049 35 RIC STD Send $100 list Eric Clutton 913 Cedar Lane Tullahoma Tenn 37388 Send SSAE tsr catalog sheet complete line
Edition: Model Aviation - 1988/09
Page Numbers: 44, 45, 134
TWO MONTHS AGO wrote about locating proper center-of-gravity conventional air plane Last month extended cover canard airplanes flying wing airplanes sat back thinking subject done addition requests formation mail bag has full lots good questions Rather sending answers questioners decided include better questions answer questions related wings did have straight leading trailing edges good example sent Bob Hanson Colo rado Springs CO former club mem ber president club Eglin Aero Model lers Bob working Sport Scale Fairchild A-b wanted know apply equa tions Id published earlier A-b wing looks something like Figure 1 will note center section wing rectangular outboard sections swept tapered type wing stabilizer uncom mon decided show calculate ap propriate aerodynamic centers proper centerof-gravity case Several writers have com mented use two integral equations July column daring because mag azine editors assume readers education stopped fifth grade dont think thats true what am attempt may put strain some readers backgrounds take close look area aerody namic center equations youll see can broken pieces example area equa tion shown Equation 6 can split pans B125/2 65dA First since wing symmetric about center integration can performed center wing tip answer doubled get area deal ing wing Figure 1 integration can performed separately over two pieces half wing result shown Equation 7 b/25/2 7 5 2jcidy c2dy Rb Bb/2 R w comes tough part Similar arguments can done aerodynamic center calcula tions consider symmetry investigate wing like Figure 1 youll get result shown Equation 8 b/2 8 X ifS [2jxicidY Figure 1 0 B F Rons back fInd-the-center-of-gravity mode again month time well learn find proper CG wings odd shapes such examples Read Figure 2 52 2f x2c2dy l/S{R14 Rb [l/6 R2 T2 RT D/3 R [Bb/2 R RT Note now 1/S term front equation missing original tegral equation presented July issue Lets look what have Equation 8 R/4 term location aerodynamic cen ter rectangular portion wing would calculated treated wing U 0 ac 0 &c itself Similarly long term square brackets [ ] location aerodynamic center trapezoidal portion wing youd get treated wing itself aerodynamic center location dis tances multiplied area its respective part wing after two added whole thing divided total wing area can simplify Equation 8 Equation 9 Xl X2 SI S2 aerodynamic center location distances areas two pieces wing 9 X S eads great generalization because can easily calculate aerodynamic center complicated wing stacking up spanwise pieces wing would handle wing like Fig ure 2 can use basic equations area aerodynamic center can simple sum division Equation 10 10 X x353 S S3 complicating factor using Equation 10 X distances Xl X2 X3 must same point example leading edge root chord wing shown Once youve determined location wing aerodynamic center can same thing horizontal tail use same center-of-gravity equation gave July issue save trouble having dig out July issue Im repeating equation Equation 3here 3 CG Stab Area 3 x Wing Area R2 T2 15R Admittedly probably some have no desire calculate proper centerof-gravity location airplane youre probably bored out skull now Ill quit subject move other things benefits writing column 44 Model Aviation Radio Control Sport Aerobatics Ron Van Putte III Sleepy Oaks Rd Ft Walton Beach FL 32548 Heyl did Van Putte put two aileron ser vos airplane Text has story get report personal experiences re late RC real heart-stopper last night went out flying field after work wait summertime thundershower quit before getting chance fly time stopped raining sun low sky overcast needed work out some system kinks before contest weekend fueled up airplane took off despite approaching darkness Five minutes flight rolled air plane inverted Reverse Cuban Eight didnt stop rolling assumed aileron servo failed put opposite aileron control stopped roll though could see airplane silhouette able nurse airplane bumpy safe landing Sure enough aileron servo failed able save airplane because has two aile ron servos aileron also have two elevator servos elevator Obviously purpose second servo give chance save airplane case quits worked fine figure extra servo weighs about 1 /2 oz can toler ate three ounces extra two servos add weight airplane What does two ex tra servos cost lot less new airplane/ engine/radio End sermon What would like see write about column would glad hear Two modelers did let know Frank Prestwood Valparaiso FL suggested write about servo torque requirements proper choice servos can made Good idea years ago Kraft Systems came out KPS-12 servo tiny jewel compared other servos yesteryear Its small compared todays servos Pat tern fliers put KPS-12 servos 100-mph ships performed adequately memory serves output torque KPS 12 servo 17-19 inch-ounces case doesnt mean anything average servo being sold today has output torque 35-45 inchounces Does mean KPS- 12 inadequate 100-mph Pattern ships Probably price pay inadequate servo torque re duced airplane responsiveness strong fast servo starts stops maneuvers crisply low-torque servo weak servo can suffer control surface blowback example perform loop higher speed backside loop puts higher load elevator servo may able resist load elevator will ac tually blow back smaller deflection angle means might enough eleva tor deflection pull airplane through bot tom loop Nobody likes loops end up looking like Figure Nines Now above discussion doesnt help deciding what servo use particular applica tion So what intend make some com putations will enable flier use some rule-of-thumb procedures application Ob viously procedures will have consider such variables airplane maneuver air speed control horn lengths servo-arm size like will take some time right So plan seeing column issue right af ter Nats report other suggested topics came Ralph Grose Riverside CA Ralph wants discussion what lift distribution looks like wing showing effects different wing shapes Continued page 134 DISTRIBUTED BY SMITh END ff815558 7555 5xr Gxbnel Soxd cdro CA 93422 4561717 Classic Glass Grumman Wildcat KIT FEATURES Polyester fiberglass fusalage cowling retractable landing 92 wingspan gear Foam cores wing stab Available major production variations F4F-3 -3A -4 FM-i FM-2 Semi-Kit Fusalage cowling foam cores wing $27500 stab canopy retractable landing gear plans Complete Kit Everything listed semi-kit plus wood parts hardware necessary complete kit including 1/64 plywood sheeting wings $45000 Deluxe Kit Complete kit fusalage preassembled $85000 wings stab presheeted control surfaces prebuilt add $1500 shipping Information Package $100 /MasterCard acceptedIdaho res add 5% sales rex Mike Zamber Classic Glass PO Box 503 Blackfoot Idaho 83221-0503 85-2309 September 1988 45 $975AVAILABLE AT AMERICAS$525 FINEST HOBBY SHOPS Carbon Fiber Laminates Aerospace Composite Products offers variety rigid carbon fiber epoxy sheets add stiffness almost material- fiberglass foam baisawood laminates can used reinforce foam wings leading trailing edges wing spars Carbon Fiber bonds easily slow setting cyanoacrylates 5-Minute epoxies laminate can stripped narrower widths CL-i007thick1x36-$4001x48-$500Px72-$700 CL-2 014 thick Vx36- $700 Px48- $800 Px72- $1100 CL-3 022 thick 1x36 $900 Px48- $1100 1x72- $1500 CL-4 OSOlhick Px36-$1100 Px48- $1400 Px72- $1800 Send SASE information additional sizes products Add $300 shipping handling Calif Residents add 6% tax Overseas orders add 15%- Order COD send check money order Aerospace Composite Products PO Box 16621 Irvine CA 92714- 714 250-1107 Source LightweIght Materials 115 Scale Z2ZtWincheEZ NEW SPACE SAVING CONTAINER FitsinYourBox 2Ax7%highx9% Tough Rigid Polyethylene udes Tubing eners Lock Tubing Through Cap ostage North Products PO Box 18419 Cleveland Heights OH 44118 II'I pack balanced cell shorted probably makes sense replace bad cell pair cells thats way packaged As can see pictures cells Kraft synthesizer transmitter packaged pairs replaced whole pack need transmitter Myers/Aberle tests want best contact friend Larry Sribnick SR Batteries Box 287 Bellport NY 11713 516 286-0079 SR can will supply packs connectors equipment manufactured Ace RJC Airtronics Cannon Cirrus Cox/Sanwa Futaba Kraft Tower some World Engines anything Deans con nector cant find source manufacturers connector can always use Deans Connectors Ace R/C see above contact SR help As example havent able find source Hi-Tee connec tor used Polks World Engines use Deans As cells themselves SR will suggest al ternatives like SR900s will fit place SOOs will make up packs special configu rations number cells L shapes stacked packs etc keep up-todate file original transmitter battery pack con figurations can make up literally pack need Though dont like doing SR will re place individual cells pack chafg ing $2 over cost materials giving pack full five-day test sequence insure worthy continued use Some manufacturers make battery pack replace ment simple plug-in matter Airtronlcs others make take apart transmitter af fair case Kraft faced latter situation least bit hesitant about making change turn prob lem over serviceman Check warranty first Im still vacation Happy flying Noise/Weiss Continued page 43 D Always build maintain air craft ensure minimum vibration levels Sounds vibrating pushrods loose fit tings loose coverings less-than-solid airframes contribute noise lot room research experimenta tion engine-mounting techniques related structural considerations E Last least some minor per formance compromises will sometimes necessary keep flying sites will ing accept open mind Once get familiar terms quieter aircraft will actually enjoy results effort Conclusions todays world us have no choice sound process model aircraft Much research work experimentation remain done little know right now can go long way toward reducing noise keeping flying fields hope manufacturers will get involved future since too have lot stake technology us today success depends applying specific problems Future research experimentation may provide bet ter methods meet lower sound objec tives have gratified other fliers club geographic area have shown greater awareness need fly quietlyand increasing interest involvement achieving goal breaking old habits developing new ones may find enjoy hobby past will really appreciate quieter models flight line Ive shared above information order fill needa need ef fective simple starting point embark upon sound proces sing approach quiet flight predict will new information new prod ucts appearing increasing rate meantime invest some time effort have fun above keep em flying RC AerobaticsNan Putte Continued page 45 Hed also like read about what expect bending moment center wing Obvi ously both topics tied together Ill work soon can Any other ideas RC Slope Soaring/Triebes Continued page 47 art system indispensable some competitive thermal flying and/or F3B As investing much money system really get what pay have inten tions continuing sport years come will undoubtedly run need such capabilities future true other things might well get best possible radio system can afford recently received letter Pierre Dume nil expressed very interesting idea malting videotape Slope Soaring finlshed will available clubs area would like get people involved Slope Soaring tape will great way show just what facet Soaring about Most people reluctant get involved something havent seen great way get Slope Soaring expo sure deserves talk Pierre sounds video going very highquality production shows aspects Slope Soaring youd like get copy videotape should available very soon just let know will pass word Pierre would like mention again will International Slope Race F3F Denmark sometime 1989 Anyone interested going either spectator competitor should get touch soon possible looks like will truly incredible event have urge go would highly rec ommend would really like thank whove sent letters and/or called response writings Slope Soaring response has greater ever imagined love help will able bring Slope Soaring forefront RC Soaring So keep letters photos calls coming 134 Model Aviation LiqIii LINE SYSTEMS P0 Box 1502 Lewiston 04241 FOAM CORE FLOATS PLANS AND KITS WE OFFER SELECTION OF FLOAT PLANS AND KITS FOR 4 12 POUND AIRPLANES WITH Y HULL ESIGN IN USE SINCE 1972 SEND SASE FOR CATALOG SHEET KIRCHER R/C PRODUCTS [NC 9 SHEFFIELD WAY CLARK NJ 07066 i A WE BUILD YOUR HELl TEST YOUR HELl PAIR YOUR HELl 322 North 7th St 64$ V11 Lehighton Pa 18235 WRITE OR CALL FOR INFORMA TION WOAL55 SOO5ST SCALP PHOtO SESVCP 500 PHOTO PACKS PLANS 3 VIEWS PHOTO-PACKS PLANS ENLARGING S*SE EnISr5O5 COPS lip Pepin&s Catalog $oo 60 pagesSCALE PlANS Eli PHOTO SERVICE 3209 Madsoo GeensOooo N C 27403 Phoop lnIal2a25239 INs ColleCt 77T L4TNES MILS lIETALS B00S PRECISI0N ISJSTR.MENTS - - CClIPFTE CAI$00 $200 IOn 8 SeIonR2 Sprngfo12 O8~ 43505 mpa 513 3220562 PAWU DIESELS Englands Finest 049 35 RIC STD Send $100 list Eric Clutton 913 Cedar Lane Tullahoma Tenn 37388 Send SSAE tsr catalog sheet complete line
Edition: Model Aviation - 1988/09
Page Numbers: 44, 45, 134
TWO MONTHS AGO wrote about locating proper center-of-gravity conventional air plane Last month extended cover canard airplanes flying wing airplanes sat back thinking subject done addition requests formation mail bag has full lots good questions Rather sending answers questioners decided include better questions answer questions related wings did have straight leading trailing edges good example sent Bob Hanson Colo rado Springs CO former club mem ber president club Eglin Aero Model lers Bob working Sport Scale Fairchild A-b wanted know apply equa tions Id published earlier A-b wing looks something like Figure 1 will note center section wing rectangular outboard sections swept tapered type wing stabilizer uncom mon decided show calculate ap propriate aerodynamic centers proper centerof-gravity case Several writers have com mented use two integral equations July column daring because mag azine editors assume readers education stopped fifth grade dont think thats true what am attempt may put strain some readers backgrounds take close look area aerody namic center equations youll see can broken pieces example area equa tion shown Equation 6 can split pans B125/2 65dA First since wing symmetric about center integration can performed center wing tip answer doubled get area deal ing wing Figure 1 integration can performed separately over two pieces half wing result shown Equation 7 b/25/2 7 5 2jcidy c2dy Rb Bb/2 R w comes tough part Similar arguments can done aerodynamic center calcula tions consider symmetry investigate wing like Figure 1 youll get result shown Equation 8 b/2 8 X ifS [2jxicidY Figure 1 0 B F Rons back fInd-the-center-of-gravity mode again month time well learn find proper CG wings odd shapes such examples Read Figure 2 52 2f x2c2dy l/S{R14 Rb [l/6 R2 T2 RT D/3 R [Bb/2 R RT Note now 1/S term front equation missing original tegral equation presented July issue Lets look what have Equation 8 R/4 term location aerodynamic cen ter rectangular portion wing would calculated treated wing U 0 ac 0 &c itself Similarly long term square brackets [ ] location aerodynamic center trapezoidal portion wing youd get treated wing itself aerodynamic center location dis tances multiplied area its respective part wing after two added whole thing divided total wing area can simplify Equation 8 Equation 9 Xl X2 SI S2 aerodynamic center location distances areas two pieces wing 9 X S eads great generalization because can easily calculate aerodynamic center complicated wing stacking up spanwise pieces wing would handle wing like Fig ure 2 can use basic equations area aerodynamic center can simple sum division Equation 10 10 X x353 S S3 complicating factor using Equation 10 X distances Xl X2 X3 must same point example leading edge root chord wing shown Once youve determined location wing aerodynamic center can same thing horizontal tail use same center-of-gravity equation gave July issue save trouble having dig out July issue Im repeating equation Equation 3here 3 CG Stab Area 3 x Wing Area R2 T2 15R Admittedly probably some have no desire calculate proper centerof-gravity location airplane youre probably bored out skull now Ill quit subject move other things benefits writing column 44 Model Aviation Radio Control Sport Aerobatics Ron Van Putte III Sleepy Oaks Rd Ft Walton Beach FL 32548 Heyl did Van Putte put two aileron ser vos airplane Text has story get report personal experiences re late RC real heart-stopper last night went out flying field after work wait summertime thundershower quit before getting chance fly time stopped raining sun low sky overcast needed work out some system kinks before contest weekend fueled up airplane took off despite approaching darkness Five minutes flight rolled air plane inverted Reverse Cuban Eight didnt stop rolling assumed aileron servo failed put opposite aileron control stopped roll though could see airplane silhouette able nurse airplane bumpy safe landing Sure enough aileron servo failed able save airplane because has two aile ron servos aileron also have two elevator servos elevator Obviously purpose second servo give chance save airplane case quits worked fine figure extra servo weighs about 1 /2 oz can toler ate three ounces extra two servos add weight airplane What does two ex tra servos cost lot less new airplane/ engine/radio End sermon What would like see write about column would glad hear Two modelers did let know Frank Prestwood Valparaiso FL suggested write about servo torque requirements proper choice servos can made Good idea years ago Kraft Systems came out KPS-12 servo tiny jewel compared other servos yesteryear Its small compared todays servos Pat tern fliers put KPS-12 servos 100-mph ships performed adequately memory serves output torque KPS 12 servo 17-19 inch-ounces case doesnt mean anything average servo being sold today has output torque 35-45 inchounces Does mean KPS- 12 inadequate 100-mph Pattern ships Probably price pay inadequate servo torque re duced airplane responsiveness strong fast servo starts stops maneuvers crisply low-torque servo weak servo can suffer control surface blowback example perform loop higher speed backside loop puts higher load elevator servo may able resist load elevator will ac tually blow back smaller deflection angle means might enough eleva tor deflection pull airplane through bot tom loop Nobody likes loops end up looking like Figure Nines Now above discussion doesnt help deciding what servo use particular applica tion So what intend make some com putations will enable flier use some rule-of-thumb procedures application Ob viously procedures will have consider such variables airplane maneuver air speed control horn lengths servo-arm size like will take some time right So plan seeing column issue right af ter Nats report other suggested topics came Ralph Grose Riverside CA Ralph wants discussion what lift distribution looks like wing showing effects different wing shapes Continued page 134 DISTRIBUTED BY SMITh END ff815558 7555 5xr Gxbnel Soxd cdro CA 93422 4561717 Classic Glass Grumman Wildcat KIT FEATURES Polyester fiberglass fusalage cowling retractable landing 92 wingspan gear Foam cores wing stab Available major production variations F4F-3 -3A -4 FM-i FM-2 Semi-Kit Fusalage cowling foam cores wing $27500 stab canopy retractable landing gear plans Complete Kit Everything listed semi-kit plus wood parts hardware necessary complete kit including 1/64 plywood sheeting wings $45000 Deluxe Kit Complete kit fusalage preassembled $85000 wings stab presheeted control surfaces prebuilt add $1500 shipping Information Package $100 /MasterCard acceptedIdaho res add 5% sales rex Mike Zamber Classic Glass PO Box 503 Blackfoot Idaho 83221-0503 85-2309 September 1988 45 $975AVAILABLE AT AMERICAS$525 FINEST HOBBY SHOPS Carbon Fiber Laminates Aerospace Composite Products offers variety rigid carbon fiber epoxy sheets add stiffness almost material- fiberglass foam baisawood laminates can used reinforce foam wings leading trailing edges wing spars Carbon Fiber bonds easily slow setting cyanoacrylates 5-Minute epoxies laminate can stripped narrower widths CL-i007thick1x36-$4001x48-$500Px72-$700 CL-2 014 thick Vx36- $700 Px48- $800 Px72- $1100 CL-3 022 thick 1x36 $900 Px48- $1100 1x72- $1500 CL-4 OSOlhick Px36-$1100 Px48- $1400 Px72- $1800 Send SASE information additional sizes products Add $300 shipping handling Calif Residents add 6% tax Overseas orders add 15%- Order COD send check money order Aerospace Composite Products PO Box 16621 Irvine CA 92714- 714 250-1107 Source LightweIght Materials 115 Scale Z2ZtWincheEZ NEW SPACE SAVING CONTAINER FitsinYourBox 2Ax7%highx9% Tough Rigid Polyethylene udes Tubing eners Lock Tubing Through Cap ostage North Products PO Box 18419 Cleveland Heights OH 44118 II'I pack balanced cell shorted probably makes sense replace bad cell pair cells thats way packaged As can see pictures cells Kraft synthesizer transmitter packaged pairs replaced whole pack need transmitter Myers/Aberle tests want best contact friend Larry Sribnick SR Batteries Box 287 Bellport NY 11713 516 286-0079 SR can will supply packs connectors equipment manufactured Ace RJC Airtronics Cannon Cirrus Cox/Sanwa Futaba Kraft Tower some World Engines anything Deans con nector cant find source manufacturers connector can always use Deans Connectors Ace R/C see above contact SR help As example havent able find source Hi-Tee connec tor used Polks World Engines use Deans As cells themselves SR will suggest al ternatives like SR900s will fit place SOOs will make up packs special configu rations number cells L shapes stacked packs etc keep up-todate file original transmitter battery pack con figurations can make up literally pack need Though dont like doing SR will re place individual cells pack chafg ing $2 over cost materials giving pack full five-day test sequence insure worthy continued use Some manufacturers make battery pack replace ment simple plug-in matter Airtronlcs others make take apart transmitter af fair case Kraft faced latter situation least bit hesitant about making change turn prob lem over serviceman Check warranty first Im still vacation Happy flying Noise/Weiss Continued page 43 D Always build maintain air craft ensure minimum vibration levels Sounds vibrating pushrods loose fit tings loose coverings less-than-solid airframes contribute noise lot room research experimenta tion engine-mounting techniques related structural considerations E Last least some minor per formance compromises will sometimes necessary keep flying sites will ing accept open mind Once get familiar terms quieter aircraft will actually enjoy results effort Conclusions todays world us have no choice sound process model aircraft Much research work experimentation remain done little know right now can go long way toward reducing noise keeping flying fields hope manufacturers will get involved future since too have lot stake technology us today success depends applying specific problems Future research experimentation may provide bet ter methods meet lower sound objec tives have gratified other fliers club geographic area have shown greater awareness need fly quietlyand increasing interest involvement achieving goal breaking old habits developing new ones may find enjoy hobby past will really appreciate quieter models flight line Ive shared above information order fill needa need ef fective simple starting point embark upon sound proces sing approach quiet flight predict will new information new prod ucts appearing increasing rate meantime invest some time effort have fun above keep em flying RC AerobaticsNan Putte Continued page 45 Hed also like read about what expect bending moment center wing Obvi ously both topics tied together Ill work soon can Any other ideas RC Slope Soaring/Triebes Continued page 47 art system indispensable some competitive thermal flying and/or F3B As investing much money system really get what pay have inten tions continuing sport years come will undoubtedly run need such capabilities future true other things might well get best possible radio system can afford recently received letter Pierre Dume nil expressed very interesting idea malting videotape Slope Soaring finlshed will available clubs area would like get people involved Slope Soaring tape will great way show just what facet Soaring about Most people reluctant get involved something havent seen great way get Slope Soaring expo sure deserves talk Pierre sounds video going very highquality production shows aspects Slope Soaring youd like get copy videotape should available very soon just let know will pass word Pierre would like mention again will International Slope Race F3F Denmark sometime 1989 Anyone interested going either spectator competitor should get touch soon possible looks like will truly incredible event have urge go would highly rec ommend would really like thank whove sent letters and/or called response writings Slope Soaring response has greater ever imagined love help will able bring Slope Soaring forefront RC Soaring So keep letters photos calls coming 134 Model Aviation LiqIii LINE SYSTEMS P0 Box 1502 Lewiston 04241 FOAM CORE FLOATS PLANS AND KITS WE OFFER SELECTION OF FLOAT PLANS AND KITS FOR 4 12 POUND AIRPLANES WITH Y HULL ESIGN IN USE SINCE 1972 SEND SASE FOR CATALOG SHEET KIRCHER R/C PRODUCTS [NC 9 SHEFFIELD WAY CLARK NJ 07066 i A WE BUILD YOUR HELl TEST YOUR HELl PAIR YOUR HELl 322 North 7th St 64$ V11 Lehighton Pa 18235 WRITE OR CALL FOR INFORMA TION WOAL55 SOO5ST SCALP PHOtO SESVCP 500 PHOTO PACKS PLANS 3 VIEWS PHOTO-PACKS PLANS ENLARGING S*SE EnISr5O5 COPS lip Pepin&s Catalog $oo 60 pagesSCALE PlANS Eli PHOTO SERVICE 3209 Madsoo GeensOooo N C 27403 Phoop lnIal2a25239 INs ColleCt 77T L4TNES MILS lIETALS B00S PRECISI0N ISJSTR.MENTS - - CClIPFTE CAI$00 $200 IOn 8 SeIonR2 Sprngfo12 O8~ 43505 mpa 513 3220562 PAWU DIESELS Englands Finest 049 35 RIC STD Send $100 list Eric Clutton 913 Cedar Lane Tullahoma Tenn 37388 Send SSAE tsr catalog sheet complete line