U EEEEEEEEEEEEEEEE pikethe Project Three-Way series article resulted reader suggestion LMillions /2A engines have produced over years lions share have produced Cox its line readyto-fly control line models engines still garages attics across land still usable asked Larry Renger discuss evolution engines well care feeding cox ENGINES U cox ENGINES U COX ENGINES U C 0 x rn z 0 z m U C 0 x ii z 0 m U C 0 x ENGINES U COX ENGINES U COX ENGII Eu. ENS backg PART IN r ound June1996 11 7S U COX II U 44 ST purpose article describe various Cox 049s construction appropriate application Part II July 1996 issue will get engine care running modification Cox began 1945 pop guna toy gun used simple piston pump make cork go pop shooting sound Sinple cuteit sold great Since just end WW II materials wood string since metal still limited availability As followup Roy Cox made wooden car dragged circle string-and-stick system also successful followed deluxe version made aluminum castings Tether-car racing very popular about time Roys cars being modified engine power Seeing trend arranged Cameron Brothers mount engines cars sold line powered cars increasing performance Finally 1949 first Cox-designed engine used cars followed year two later first Cox-manufactured engines peak popularity million Cox 049 engines produced year Consider that time two other major manufacturers nearly same size couple decades total 049 engine sales about same car sales Because low price huge volume production ready availability modelers have always regarded engines throwaway commodity rather precision jewels really Hideous mistreatment wrong fuel incorrect props standard fare small engine wouldnt treat watch way engine tolerances lot tighter As result misunderstandings small engines have reputation being finicky short life reality 049 run proper fuel prop needlevalve setting run jn clean environment will last long time Cox ran test some yeafs ago after 400 hours engine would require electric staffing would still run EEEEEEEEEE ENGINE DESIGN FEATURES Basics two-stroke engine part pump part power generator 12 Model Aviation ss porting Cox engines lOft right twin booster Silt exhaust L prevents fuel ignition outside grooves single groove standard porting engine Open exhaust R yieids smidgen power Ph-t 1~ th thn Heather Erdahi Texaco L standard head share Hemi shape High- Ready-to-Fly firewall backpiatethe basic reed-valve induction compression head R has squish band Coli wire sizes differ too system Engine pressure seals reed venturi opening U engine has pump fuel/air mixture cylinder ignited produce power Most design performance differences come pumping flow designnot head combustion design cant get lot mix cylinder arent going get lot power out key get smooth flow mix waste exhaust out minimum time definitely case more Most engine designs use three techniques get fuel/air mix engines combustion chamber parts pumping action engine split intake bypass exhaust systems Intake systems reasonably independent bypass exhaust systems must work together will clarified hope go along Intake systems technique used suck air engine combine fuel create well-vaporized mix will bum smoothly rapidly three basic systems control intake timing engine simplest side-port second reed valve complex rotary timed engine Rotary type crankshafts L-R Medallion sport timing Tee Dee standard special helicopter crank almost engines venturi tube fuel drawn reduced pressure spray airstream intake valving systems intended provide maximum fuel air draw within constraints complexity expense Other considerations easy handling steady needle setting fuel draw through high g maneuvers side-port very old system still used replica engines principle bottom piston uncovers intake top stroke good vacuum crankcase strong suction topl mixture through venturi past needle valve type induction system extremely reliable trouble-free leads easy starting solid run characteristics very limited much power can generated engine since timing symmetrical about top-dead-center position engine will run right left rotation second system used Cox engines reedvalve intake floating reed made Mylar used seal venturi whenever pressure crankcase open up Reed-valve cranks stock L competition Note stronger support crankpin drilled pin lighter Weight c cc u ri gineExhaust Bypass Sub-Piston Piston Taper HeadValve Crankshaft TankMisceiianeousPurpose PortBoosterinductionWeight GrindTypeTypeType Standard Pro4SiltNoNoStdNoLow StdReedStdExternalScreened VentuilRegiMar RTF Power High Pert ProdnSlit1NoStdNoLow StdReedStdExternalScreened VenturiRTF CL Stunt Lazy Bee Babe BeeSitNoNoStdNoLow Std Reed StdSm MetalFree-Flight VentsTrainer Models Bisok WidowOpenNoYesStdNoLow Std Reed StdLg MetalCL Stunt VentIngSport Models DragonflyStt1NoSidNoLow Std Reed StdXLg. Plastic Clunk & Vents forRC Sport Models RC Throttle/Muffler TexacoSlit1NoStdNoLow 5-Fin ReedStdLg. MetalFree-Flight ventsFE Camp Texaco JrSlit1NoStdNoLow 5-Fin ReedStdSm MetalFreeFiight VentsFE Comp Kiiier BeeSlit1YesLightYesHigh ReedCompExternalSpecial VentisiCamp VenomOpen1YesUghtYesHigh ReedCampLg MetalCL Stunt VentingCamp QRCSlitNoNoStdNoLow Std Reed StdLg MetalCL Stunt VentsSport Models Muffler MedaiiionSlit1NoStd No Low Std Rotary StdExternalBeam MountingRC Sport Models Throttle/Muffler Tee DeeOpen2YesStdYesHighRotary SidExternalBeam MountingComp Tee D R/COpen1NoLightYesLow Std Rotary CampExternalBeam MountingHigh Pert RC Carburetor & Muffler June1996 13 slight vacuum Now engine can pull fuel/air mixture whenever demand just piston top stroke As side-port engine reed-valved engines may run either direction Since crankcase drawing demand engines work beautifully over very large speed range start easily final system rotary timed intake several configurations common has port crankshaft venturi mounted front crankcase Timing achieved port shaft rotates around uncover venturi Since timing may precisely controlled engine may tuned docile sport engine fire breathing racer Handling starting usable speed range determined engine timing example Tee Dee series set up racing Medallions sport ability control timing allows much higher rpm thai can achieved reed sideport system Bypass porting technique used get fuel/air mix cylinder always closely related its design exhaust system since both must work through same cylinder walls Bypass porting falls three basic fonns 360 porting loop scavenged Schnuerle porting 360 porting idea smoothly flow fresh mixture sides exhausting burned mix also sides working right intake shoots up center cylinder pushing exhaust down outsides through exhaust ports Only few diesels such PAW use anymore though system choice OK Cub Atwood early Holland engines Loop scavenging technique uses single bypass exhaust separate sides engine baffle piston redirects intake upward scavenges pushes out exhaust Strange head shapes required clear piston baffle smooth combustion characteristics require much experimentation part designer system standard large engines such K&B Fox McCoy smallest engine can remember used technique Anderson Royal Spitfire 065 Finally get Schnuerle system porting Cox engines use original system outlined Schnuerles patents two bypasses opposite sides cylinder two exhausts 90 Later modifications large engines have resulted two main bypasses moving closer together small booster different timing located between exhaust opposite wall sophisticated bypass/exhaust schemes works well allows engine design start easily still have racing performance small engines few imports East Germany Russia use advanced system WHICH ENGINE IS WHICH Cox engines have used bewildering array components over years can interchanged produce uncountable variety possible configurations Because Ill stick design current engines article will get mix-and-match modifications along some hop-up tips Part II Currently 21 engines hobby line two used ready-to-fly airplanes variety necessary because different applications modeling Since now major manufacturer Cox makes types engines type flying isnt like big engines might buy K&B ducted fan Fox Stunt Nelson racing Some features cost make oaly would useless detrimental certain applications As result Cox engines vary widely price depending complex make selling margin Cox products roughiy constant what pay directly related what cost make Cylinders now have two main bypasses two exhausts mentioned above addition however may have two additional booster grooves per bypass exhaust ports may open slits may may have subpiston induction SPI technique bottom piston uncovers bottom exhaust port top stroke opening seems smooth out running high speed allowing last liffle puff fresh air crankcase Perhaps cools piston perhaps helps fill top case doubt anyone genuinely knows works final difference among cylinders relates finally ground finish device called hone used smooth walls cylinder achieve precise dimensions needed final grind can constant diameter have change bottom top Low-end engines have straight bore makes easier assure perfect seal easy starting Higher-performance engines need taper piston cylinder compensate higher heating near head taper reduces seal bottom stroke makes starting bit harder As things have pick what need cant have Pistons Cox makes three basic types heavy wall light-wall tapered untapered light-wall pistons originally developed Killer Bee high performance reed-valve engine gain experience will likely used more engines line Crankshafts Again several combinations shafts may reed rotary engines rotary sporttimed Medallion race-timed Tee Dees now also two different balance systems use original smile counterweight cut back shaft new competition balance system originated Tee Dee RIC now used Killer Bee Venom Tee Dee Helicopter engine used Light Machines Glow Heads Three types use Cox Most common standard-compression bead found Babe Bees Ready-to-Fly RTF engines second head identical internal configuration extra cooling fin use Texaco engines Finally high-compression head used Tee Dees Killer Bees Venom also variety outside manufacturers make special-application heads such GloBee Galbreath/Nelson Davis Diesel RIL diesel conversions beyond scope article get specials Backplates reed engines have choice two backplates four different tanks have needle valve reedvalve system built standard RTF backplate features small venturi screen over back prevent large bits junk jamming reed valve backplate developed Killer Bee variation features beveled intake no screen bigger-bore venturi special chamfer just under reed valve smoother flow RTF version works great low nitro big props Fuel draw easy starting maximized running engine fast however venturi must opened up allow air flow higher velocity air helps maintain good fuel draw though Killer Bee opening made large possible starting needle sensitivity somewhat worse RTF version Fuel Tanks Fuel tanks may metal plastic long short have vents Stunt free fught Babe Bee tank short metal has free-ffight venting Black Widow tank long metal has Stunt venting Texaco tank long metal free flight vented Dragonfly tank plastic very large Stunt vented has clunk fuel pickup aerobatic RC flying basics put together useable format chart gives characteristics engine presented hope background enough prepare Part II Running Ruining Fixing Hopping-Up Cox engines odel Aviation
Edition: Model Aviation - 1996/06
Page Numbers: 11, 12, 13, 14
U EEEEEEEEEEEEEEEE pikethe Project Three-Way series article resulted reader suggestion LMillions /2A engines have produced over years lions share have produced Cox its line readyto-fly control line models engines still garages attics across land still usable asked Larry Renger discuss evolution engines well care feeding cox ENGINES U cox ENGINES U COX ENGINES U C 0 x rn z 0 z m U C 0 x ii z 0 m U C 0 x ENGINES U COX ENGINES U COX ENGII Eu. ENS backg PART IN r ound June1996 11 7S U COX II U 44 ST purpose article describe various Cox 049s construction appropriate application Part II July 1996 issue will get engine care running modification Cox began 1945 pop guna toy gun used simple piston pump make cork go pop shooting sound Sinple cuteit sold great Since just end WW II materials wood string since metal still limited availability As followup Roy Cox made wooden car dragged circle string-and-stick system also successful followed deluxe version made aluminum castings Tether-car racing very popular about time Roys cars being modified engine power Seeing trend arranged Cameron Brothers mount engines cars sold line powered cars increasing performance Finally 1949 first Cox-designed engine used cars followed year two later first Cox-manufactured engines peak popularity million Cox 049 engines produced year Consider that time two other major manufacturers nearly same size couple decades total 049 engine sales about same car sales Because low price huge volume production ready availability modelers have always regarded engines throwaway commodity rather precision jewels really Hideous mistreatment wrong fuel incorrect props standard fare small engine wouldnt treat watch way engine tolerances lot tighter As result misunderstandings small engines have reputation being finicky short life reality 049 run proper fuel prop needlevalve setting run jn clean environment will last long time Cox ran test some yeafs ago after 400 hours engine would require electric staffing would still run EEEEEEEEEE ENGINE DESIGN FEATURES Basics two-stroke engine part pump part power generator 12 Model Aviation ss porting Cox engines lOft right twin booster Silt exhaust L prevents fuel ignition outside grooves single groove standard porting engine Open exhaust R yieids smidgen power Ph-t 1~ th thn Heather Erdahi Texaco L standard head share Hemi shape High- Ready-to-Fly firewall backpiatethe basic reed-valve induction compression head R has squish band Coli wire sizes differ too system Engine pressure seals reed venturi opening U engine has pump fuel/air mixture cylinder ignited produce power Most design performance differences come pumping flow designnot head combustion design cant get lot mix cylinder arent going get lot power out key get smooth flow mix waste exhaust out minimum time definitely case more Most engine designs use three techniques get fuel/air mix engines combustion chamber parts pumping action engine split intake bypass exhaust systems Intake systems reasonably independent bypass exhaust systems must work together will clarified hope go along Intake systems technique used suck air engine combine fuel create well-vaporized mix will bum smoothly rapidly three basic systems control intake timing engine simplest side-port second reed valve complex rotary timed engine Rotary type crankshafts L-R Medallion sport timing Tee Dee standard special helicopter crank almost engines venturi tube fuel drawn reduced pressure spray airstream intake valving systems intended provide maximum fuel air draw within constraints complexity expense Other considerations easy handling steady needle setting fuel draw through high g maneuvers side-port very old system still used replica engines principle bottom piston uncovers intake top stroke good vacuum crankcase strong suction topl mixture through venturi past needle valve type induction system extremely reliable trouble-free leads easy starting solid run characteristics very limited much power can generated engine since timing symmetrical about top-dead-center position engine will run right left rotation second system used Cox engines reedvalve intake floating reed made Mylar used seal venturi whenever pressure crankcase open up Reed-valve cranks stock L competition Note stronger support crankpin drilled pin lighter Weight c cc u ri gineExhaust Bypass Sub-Piston Piston Taper HeadValve Crankshaft TankMisceiianeousPurpose PortBoosterinductionWeight GrindTypeTypeType Standard Pro4SiltNoNoStdNoLow StdReedStdExternalScreened VentuilRegiMar RTF Power High Pert ProdnSlit1NoStdNoLow StdReedStdExternalScreened VenturiRTF CL Stunt Lazy Bee Babe BeeSitNoNoStdNoLow Std Reed StdSm MetalFree-Flight VentsTrainer Models Bisok WidowOpenNoYesStdNoLow Std Reed StdLg MetalCL Stunt VentIngSport Models DragonflyStt1NoSidNoLow Std Reed StdXLg. Plastic Clunk & Vents forRC Sport Models RC Throttle/Muffler TexacoSlit1NoStdNoLow 5-Fin ReedStdLg. MetalFree-Flight ventsFE Camp Texaco JrSlit1NoStdNoLow 5-Fin ReedStdSm MetalFreeFiight VentsFE Comp Kiiier BeeSlit1YesLightYesHigh ReedCompExternalSpecial VentisiCamp VenomOpen1YesUghtYesHigh ReedCampLg MetalCL Stunt VentingCamp QRCSlitNoNoStdNoLow Std Reed StdLg MetalCL Stunt VentsSport Models Muffler MedaiiionSlit1NoStd No Low Std Rotary StdExternalBeam MountingRC Sport Models Throttle/Muffler Tee DeeOpen2YesStdYesHighRotary SidExternalBeam MountingComp Tee D R/COpen1NoLightYesLow Std Rotary CampExternalBeam MountingHigh Pert RC Carburetor & Muffler June1996 13 slight vacuum Now engine can pull fuel/air mixture whenever demand just piston top stroke As side-port engine reed-valved engines may run either direction Since crankcase drawing demand engines work beautifully over very large speed range start easily final system rotary timed intake several configurations common has port crankshaft venturi mounted front crankcase Timing achieved port shaft rotates around uncover venturi Since timing may precisely controlled engine may tuned docile sport engine fire breathing racer Handling starting usable speed range determined engine timing example Tee Dee series set up racing Medallions sport ability control timing allows much higher rpm thai can achieved reed sideport system Bypass porting technique used get fuel/air mix cylinder always closely related its design exhaust system since both must work through same cylinder walls Bypass porting falls three basic fonns 360 porting loop scavenged Schnuerle porting 360 porting idea smoothly flow fresh mixture sides exhausting burned mix also sides working right intake shoots up center cylinder pushing exhaust down outsides through exhaust ports Only few diesels such PAW use anymore though system choice OK Cub Atwood early Holland engines Loop scavenging technique uses single bypass exhaust separate sides engine baffle piston redirects intake upward scavenges pushes out exhaust Strange head shapes required clear piston baffle smooth combustion characteristics require much experimentation part designer system standard large engines such K&B Fox McCoy smallest engine can remember used technique Anderson Royal Spitfire 065 Finally get Schnuerle system porting Cox engines use original system outlined Schnuerles patents two bypasses opposite sides cylinder two exhausts 90 Later modifications large engines have resulted two main bypasses moving closer together small booster different timing located between exhaust opposite wall sophisticated bypass/exhaust schemes works well allows engine design start easily still have racing performance small engines few imports East Germany Russia use advanced system WHICH ENGINE IS WHICH Cox engines have used bewildering array components over years can interchanged produce uncountable variety possible configurations Because Ill stick design current engines article will get mix-and-match modifications along some hop-up tips Part II Currently 21 engines hobby line two used ready-to-fly airplanes variety necessary because different applications modeling Since now major manufacturer Cox makes types engines type flying isnt like big engines might buy K&B ducted fan Fox Stunt Nelson racing Some features cost make oaly would useless detrimental certain applications As result Cox engines vary widely price depending complex make selling margin Cox products roughiy constant what pay directly related what cost make Cylinders now have two main bypasses two exhausts mentioned above addition however may have two additional booster grooves per bypass exhaust ports may open slits may may have subpiston induction SPI technique bottom piston uncovers bottom exhaust port top stroke opening seems smooth out running high speed allowing last liffle puff fresh air crankcase Perhaps cools piston perhaps helps fill top case doubt anyone genuinely knows works final difference among cylinders relates finally ground finish device called hone used smooth walls cylinder achieve precise dimensions needed final grind can constant diameter have change bottom top Low-end engines have straight bore makes easier assure perfect seal easy starting Higher-performance engines need taper piston cylinder compensate higher heating near head taper reduces seal bottom stroke makes starting bit harder As things have pick what need cant have Pistons Cox makes three basic types heavy wall light-wall tapered untapered light-wall pistons originally developed Killer Bee high performance reed-valve engine gain experience will likely used more engines line Crankshafts Again several combinations shafts may reed rotary engines rotary sporttimed Medallion race-timed Tee Dees now also two different balance systems use original smile counterweight cut back shaft new competition balance system originated Tee Dee RIC now used Killer Bee Venom Tee Dee Helicopter engine used Light Machines Glow Heads Three types use Cox Most common standard-compression bead found Babe Bees Ready-to-Fly RTF engines second head identical internal configuration extra cooling fin use Texaco engines Finally high-compression head used Tee Dees Killer Bees Venom also variety outside manufacturers make special-application heads such GloBee Galbreath/Nelson Davis Diesel RIL diesel conversions beyond scope article get specials Backplates reed engines have choice two backplates four different tanks have needle valve reedvalve system built standard RTF backplate features small venturi screen over back prevent large bits junk jamming reed valve backplate developed Killer Bee variation features beveled intake no screen bigger-bore venturi special chamfer just under reed valve smoother flow RTF version works great low nitro big props Fuel draw easy starting maximized running engine fast however venturi must opened up allow air flow higher velocity air helps maintain good fuel draw though Killer Bee opening made large possible starting needle sensitivity somewhat worse RTF version Fuel Tanks Fuel tanks may metal plastic long short have vents Stunt free fught Babe Bee tank short metal has free-ffight venting Black Widow tank long metal has Stunt venting Texaco tank long metal free flight vented Dragonfly tank plastic very large Stunt vented has clunk fuel pickup aerobatic RC flying basics put together useable format chart gives characteristics engine presented hope background enough prepare Part II Running Ruining Fixing Hopping-Up Cox engines odel Aviation
Edition: Model Aviation - 1996/06
Page Numbers: 11, 12, 13, 14
U EEEEEEEEEEEEEEEE pikethe Project Three-Way series article resulted reader suggestion LMillions /2A engines have produced over years lions share have produced Cox its line readyto-fly control line models engines still garages attics across land still usable asked Larry Renger discuss evolution engines well care feeding cox ENGINES U cox ENGINES U COX ENGINES U C 0 x rn z 0 z m U C 0 x ii z 0 m U C 0 x ENGINES U COX ENGINES U COX ENGII Eu. ENS backg PART IN r ound June1996 11 7S U COX II U 44 ST purpose article describe various Cox 049s construction appropriate application Part II July 1996 issue will get engine care running modification Cox began 1945 pop guna toy gun used simple piston pump make cork go pop shooting sound Sinple cuteit sold great Since just end WW II materials wood string since metal still limited availability As followup Roy Cox made wooden car dragged circle string-and-stick system also successful followed deluxe version made aluminum castings Tether-car racing very popular about time Roys cars being modified engine power Seeing trend arranged Cameron Brothers mount engines cars sold line powered cars increasing performance Finally 1949 first Cox-designed engine used cars followed year two later first Cox-manufactured engines peak popularity million Cox 049 engines produced year Consider that time two other major manufacturers nearly same size couple decades total 049 engine sales about same car sales Because low price huge volume production ready availability modelers have always regarded engines throwaway commodity rather precision jewels really Hideous mistreatment wrong fuel incorrect props standard fare small engine wouldnt treat watch way engine tolerances lot tighter As result misunderstandings small engines have reputation being finicky short life reality 049 run proper fuel prop needlevalve setting run jn clean environment will last long time Cox ran test some yeafs ago after 400 hours engine would require electric staffing would still run EEEEEEEEEE ENGINE DESIGN FEATURES Basics two-stroke engine part pump part power generator 12 Model Aviation ss porting Cox engines lOft right twin booster Silt exhaust L prevents fuel ignition outside grooves single groove standard porting engine Open exhaust R yieids smidgen power Ph-t 1~ th thn Heather Erdahi Texaco L standard head share Hemi shape High- Ready-to-Fly firewall backpiatethe basic reed-valve induction compression head R has squish band Coli wire sizes differ too system Engine pressure seals reed venturi opening U engine has pump fuel/air mixture cylinder ignited produce power Most design performance differences come pumping flow designnot head combustion design cant get lot mix cylinder arent going get lot power out key get smooth flow mix waste exhaust out minimum time definitely case more Most engine designs use three techniques get fuel/air mix engines combustion chamber parts pumping action engine split intake bypass exhaust systems Intake systems reasonably independent bypass exhaust systems must work together will clarified hope go along Intake systems technique used suck air engine combine fuel create well-vaporized mix will bum smoothly rapidly three basic systems control intake timing engine simplest side-port second reed valve complex rotary timed engine Rotary type crankshafts L-R Medallion sport timing Tee Dee standard special helicopter crank almost engines venturi tube fuel drawn reduced pressure spray airstream intake valving systems intended provide maximum fuel air draw within constraints complexity expense Other considerations easy handling steady needle setting fuel draw through high g maneuvers side-port very old system still used replica engines principle bottom piston uncovers intake top stroke good vacuum crankcase strong suction topl mixture through venturi past needle valve type induction system extremely reliable trouble-free leads easy starting solid run characteristics very limited much power can generated engine since timing symmetrical about top-dead-center position engine will run right left rotation second system used Cox engines reedvalve intake floating reed made Mylar used seal venturi whenever pressure crankcase open up Reed-valve cranks stock L competition Note stronger support crankpin drilled pin lighter Weight c cc u ri gineExhaust Bypass Sub-Piston Piston Taper HeadValve Crankshaft TankMisceiianeousPurpose PortBoosterinductionWeight GrindTypeTypeType Standard Pro4SiltNoNoStdNoLow StdReedStdExternalScreened VentuilRegiMar RTF Power High Pert ProdnSlit1NoStdNoLow StdReedStdExternalScreened VenturiRTF CL Stunt Lazy Bee Babe BeeSitNoNoStdNoLow Std Reed StdSm MetalFree-Flight VentsTrainer Models Bisok WidowOpenNoYesStdNoLow Std Reed StdLg MetalCL Stunt VentIngSport Models DragonflyStt1NoSidNoLow Std Reed StdXLg. Plastic Clunk & Vents forRC Sport Models RC Throttle/Muffler TexacoSlit1NoStdNoLow 5-Fin ReedStdLg. MetalFree-Flight ventsFE Camp Texaco JrSlit1NoStdNoLow 5-Fin ReedStdSm MetalFreeFiight VentsFE Comp Kiiier BeeSlit1YesLightYesHigh ReedCompExternalSpecial VentisiCamp VenomOpen1YesUghtYesHigh ReedCampLg MetalCL Stunt VentingCamp QRCSlitNoNoStdNoLow Std Reed StdLg MetalCL Stunt VentsSport Models Muffler MedaiiionSlit1NoStd No Low Std Rotary StdExternalBeam MountingRC Sport Models Throttle/Muffler Tee DeeOpen2YesStdYesHighRotary SidExternalBeam MountingComp Tee D R/COpen1NoLightYesLow Std Rotary CampExternalBeam MountingHigh Pert RC Carburetor & Muffler June1996 13 slight vacuum Now engine can pull fuel/air mixture whenever demand just piston top stroke As side-port engine reed-valved engines may run either direction Since crankcase drawing demand engines work beautifully over very large speed range start easily final system rotary timed intake several configurations common has port crankshaft venturi mounted front crankcase Timing achieved port shaft rotates around uncover venturi Since timing may precisely controlled engine may tuned docile sport engine fire breathing racer Handling starting usable speed range determined engine timing example Tee Dee series set up racing Medallions sport ability control timing allows much higher rpm thai can achieved reed sideport system Bypass porting technique used get fuel/air mix cylinder always closely related its design exhaust system since both must work through same cylinder walls Bypass porting falls three basic fonns 360 porting loop scavenged Schnuerle porting 360 porting idea smoothly flow fresh mixture sides exhausting burned mix also sides working right intake shoots up center cylinder pushing exhaust down outsides through exhaust ports Only few diesels such PAW use anymore though system choice OK Cub Atwood early Holland engines Loop scavenging technique uses single bypass exhaust separate sides engine baffle piston redirects intake upward scavenges pushes out exhaust Strange head shapes required clear piston baffle smooth combustion characteristics require much experimentation part designer system standard large engines such K&B Fox McCoy smallest engine can remember used technique Anderson Royal Spitfire 065 Finally get Schnuerle system porting Cox engines use original system outlined Schnuerles patents two bypasses opposite sides cylinder two exhausts 90 Later modifications large engines have resulted two main bypasses moving closer together small booster different timing located between exhaust opposite wall sophisticated bypass/exhaust schemes works well allows engine design start easily still have racing performance small engines few imports East Germany Russia use advanced system WHICH ENGINE IS WHICH Cox engines have used bewildering array components over years can interchanged produce uncountable variety possible configurations Because Ill stick design current engines article will get mix-and-match modifications along some hop-up tips Part II Currently 21 engines hobby line two used ready-to-fly airplanes variety necessary because different applications modeling Since now major manufacturer Cox makes types engines type flying isnt like big engines might buy K&B ducted fan Fox Stunt Nelson racing Some features cost make oaly would useless detrimental certain applications As result Cox engines vary widely price depending complex make selling margin Cox products roughiy constant what pay directly related what cost make Cylinders now have two main bypasses two exhausts mentioned above addition however may have two additional booster grooves per bypass exhaust ports may open slits may may have subpiston induction SPI technique bottom piston uncovers bottom exhaust port top stroke opening seems smooth out running high speed allowing last liffle puff fresh air crankcase Perhaps cools piston perhaps helps fill top case doubt anyone genuinely knows works final difference among cylinders relates finally ground finish device called hone used smooth walls cylinder achieve precise dimensions needed final grind can constant diameter have change bottom top Low-end engines have straight bore makes easier assure perfect seal easy starting Higher-performance engines need taper piston cylinder compensate higher heating near head taper reduces seal bottom stroke makes starting bit harder As things have pick what need cant have Pistons Cox makes three basic types heavy wall light-wall tapered untapered light-wall pistons originally developed Killer Bee high performance reed-valve engine gain experience will likely used more engines line Crankshafts Again several combinations shafts may reed rotary engines rotary sporttimed Medallion race-timed Tee Dees now also two different balance systems use original smile counterweight cut back shaft new competition balance system originated Tee Dee RIC now used Killer Bee Venom Tee Dee Helicopter engine used Light Machines Glow Heads Three types use Cox Most common standard-compression bead found Babe Bees Ready-to-Fly RTF engines second head identical internal configuration extra cooling fin use Texaco engines Finally high-compression head used Tee Dees Killer Bees Venom also variety outside manufacturers make special-application heads such GloBee Galbreath/Nelson Davis Diesel RIL diesel conversions beyond scope article get specials Backplates reed engines have choice two backplates four different tanks have needle valve reedvalve system built standard RTF backplate features small venturi screen over back prevent large bits junk jamming reed valve backplate developed Killer Bee variation features beveled intake no screen bigger-bore venturi special chamfer just under reed valve smoother flow RTF version works great low nitro big props Fuel draw easy starting maximized running engine fast however venturi must opened up allow air flow higher velocity air helps maintain good fuel draw though Killer Bee opening made large possible starting needle sensitivity somewhat worse RTF version Fuel Tanks Fuel tanks may metal plastic long short have vents Stunt free fught Babe Bee tank short metal has free-ffight venting Black Widow tank long metal has Stunt venting Texaco tank long metal free flight vented Dragonfly tank plastic very large Stunt vented has clunk fuel pickup aerobatic RC flying basics put together useable format chart gives characteristics engine presented hope background enough prepare Part II Running Ruining Fixing Hopping-Up Cox engines odel Aviation
Edition: Model Aviation - 1996/06
Page Numbers: 11, 12, 13, 14
U EEEEEEEEEEEEEEEE pikethe Project Three-Way series article resulted reader suggestion LMillions /2A engines have produced over years lions share have produced Cox its line readyto-fly control line models engines still garages attics across land still usable asked Larry Renger discuss evolution engines well care feeding cox ENGINES U cox ENGINES U COX ENGINES U C 0 x rn z 0 z m U C 0 x ii z 0 m U C 0 x ENGINES U COX ENGINES U COX ENGII Eu. ENS backg PART IN r ound June1996 11 7S U COX II U 44 ST purpose article describe various Cox 049s construction appropriate application Part II July 1996 issue will get engine care running modification Cox began 1945 pop guna toy gun used simple piston pump make cork go pop shooting sound Sinple cuteit sold great Since just end WW II materials wood string since metal still limited availability As followup Roy Cox made wooden car dragged circle string-and-stick system also successful followed deluxe version made aluminum castings Tether-car racing very popular about time Roys cars being modified engine power Seeing trend arranged Cameron Brothers mount engines cars sold line powered cars increasing performance Finally 1949 first Cox-designed engine used cars followed year two later first Cox-manufactured engines peak popularity million Cox 049 engines produced year Consider that time two other major manufacturers nearly same size couple decades total 049 engine sales about same car sales Because low price huge volume production ready availability modelers have always regarded engines throwaway commodity rather precision jewels really Hideous mistreatment wrong fuel incorrect props standard fare small engine wouldnt treat watch way engine tolerances lot tighter As result misunderstandings small engines have reputation being finicky short life reality 049 run proper fuel prop needlevalve setting run jn clean environment will last long time Cox ran test some yeafs ago after 400 hours engine would require electric staffing would still run EEEEEEEEEE ENGINE DESIGN FEATURES Basics two-stroke engine part pump part power generator 12 Model Aviation ss porting Cox engines lOft right twin booster Silt exhaust L prevents fuel ignition outside grooves single groove standard porting engine Open exhaust R yieids smidgen power Ph-t 1~ th thn Heather Erdahi Texaco L standard head share Hemi shape High- Ready-to-Fly firewall backpiatethe basic reed-valve induction compression head R has squish band Coli wire sizes differ too system Engine pressure seals reed venturi opening U engine has pump fuel/air mixture cylinder ignited produce power Most design performance differences come pumping flow designnot head combustion design cant get lot mix cylinder arent going get lot power out key get smooth flow mix waste exhaust out minimum time definitely case more Most engine designs use three techniques get fuel/air mix engines combustion chamber parts pumping action engine split intake bypass exhaust systems Intake systems reasonably independent bypass exhaust systems must work together will clarified hope go along Intake systems technique used suck air engine combine fuel create well-vaporized mix will bum smoothly rapidly three basic systems control intake timing engine simplest side-port second reed valve complex rotary timed engine Rotary type crankshafts L-R Medallion sport timing Tee Dee standard special helicopter crank almost engines venturi tube fuel drawn reduced pressure spray airstream intake valving systems intended provide maximum fuel air draw within constraints complexity expense Other considerations easy handling steady needle setting fuel draw through high g maneuvers side-port very old system still used replica engines principle bottom piston uncovers intake top stroke good vacuum crankcase strong suction topl mixture through venturi past needle valve type induction system extremely reliable trouble-free leads easy starting solid run characteristics very limited much power can generated engine since timing symmetrical about top-dead-center position engine will run right left rotation second system used Cox engines reedvalve intake floating reed made Mylar used seal venturi whenever pressure crankcase open up Reed-valve cranks stock L competition Note stronger support crankpin drilled pin lighter Weight c cc u ri gineExhaust Bypass Sub-Piston Piston Taper HeadValve Crankshaft TankMisceiianeousPurpose PortBoosterinductionWeight GrindTypeTypeType Standard Pro4SiltNoNoStdNoLow StdReedStdExternalScreened VentuilRegiMar RTF Power High Pert ProdnSlit1NoStdNoLow StdReedStdExternalScreened VenturiRTF CL Stunt Lazy Bee Babe BeeSitNoNoStdNoLow Std Reed StdSm MetalFree-Flight VentsTrainer Models Bisok WidowOpenNoYesStdNoLow Std Reed StdLg MetalCL Stunt VentIngSport Models DragonflyStt1NoSidNoLow Std Reed StdXLg. Plastic Clunk & Vents forRC Sport Models RC Throttle/Muffler TexacoSlit1NoStdNoLow 5-Fin ReedStdLg. MetalFree-Flight ventsFE Camp Texaco JrSlit1NoStdNoLow 5-Fin ReedStdSm MetalFreeFiight VentsFE Comp Kiiier BeeSlit1YesLightYesHigh ReedCompExternalSpecial VentisiCamp VenomOpen1YesUghtYesHigh ReedCampLg MetalCL Stunt VentingCamp QRCSlitNoNoStdNoLow Std Reed StdLg MetalCL Stunt VentsSport Models Muffler MedaiiionSlit1NoStd No Low Std Rotary StdExternalBeam MountingRC Sport Models Throttle/Muffler Tee DeeOpen2YesStdYesHighRotary SidExternalBeam MountingComp Tee D R/COpen1NoLightYesLow Std Rotary CampExternalBeam MountingHigh Pert RC Carburetor & Muffler June1996 13 slight vacuum Now engine can pull fuel/air mixture whenever demand just piston top stroke As side-port engine reed-valved engines may run either direction Since crankcase drawing demand engines work beautifully over very large speed range start easily final system rotary timed intake several configurations common has port crankshaft venturi mounted front crankcase Timing achieved port shaft rotates around uncover venturi Since timing may precisely controlled engine may tuned docile sport engine fire breathing racer Handling starting usable speed range determined engine timing example Tee Dee series set up racing Medallions sport ability control timing allows much higher rpm thai can achieved reed sideport system Bypass porting technique used get fuel/air mix cylinder always closely related its design exhaust system since both must work through same cylinder walls Bypass porting falls three basic fonns 360 porting loop scavenged Schnuerle porting 360 porting idea smoothly flow fresh mixture sides exhausting burned mix also sides working right intake shoots up center cylinder pushing exhaust down outsides through exhaust ports Only few diesels such PAW use anymore though system choice OK Cub Atwood early Holland engines Loop scavenging technique uses single bypass exhaust separate sides engine baffle piston redirects intake upward scavenges pushes out exhaust Strange head shapes required clear piston baffle smooth combustion characteristics require much experimentation part designer system standard large engines such K&B Fox McCoy smallest engine can remember used technique Anderson Royal Spitfire 065 Finally get Schnuerle system porting Cox engines use original system outlined Schnuerles patents two bypasses opposite sides cylinder two exhausts 90 Later modifications large engines have resulted two main bypasses moving closer together small booster different timing located between exhaust opposite wall sophisticated bypass/exhaust schemes works well allows engine design start easily still have racing performance small engines few imports East Germany Russia use advanced system WHICH ENGINE IS WHICH Cox engines have used bewildering array components over years can interchanged produce uncountable variety possible configurations Because Ill stick design current engines article will get mix-and-match modifications along some hop-up tips Part II Currently 21 engines hobby line two used ready-to-fly airplanes variety necessary because different applications modeling Since now major manufacturer Cox makes types engines type flying isnt like big engines might buy K&B ducted fan Fox Stunt Nelson racing Some features cost make oaly would useless detrimental certain applications As result Cox engines vary widely price depending complex make selling margin Cox products roughiy constant what pay directly related what cost make Cylinders now have two main bypasses two exhausts mentioned above addition however may have two additional booster grooves per bypass exhaust ports may open slits may may have subpiston induction SPI technique bottom piston uncovers bottom exhaust port top stroke opening seems smooth out running high speed allowing last liffle puff fresh air crankcase Perhaps cools piston perhaps helps fill top case doubt anyone genuinely knows works final difference among cylinders relates finally ground finish device called hone used smooth walls cylinder achieve precise dimensions needed final grind can constant diameter have change bottom top Low-end engines have straight bore makes easier assure perfect seal easy starting Higher-performance engines need taper piston cylinder compensate higher heating near head taper reduces seal bottom stroke makes starting bit harder As things have pick what need cant have Pistons Cox makes three basic types heavy wall light-wall tapered untapered light-wall pistons originally developed Killer Bee high performance reed-valve engine gain experience will likely used more engines line Crankshafts Again several combinations shafts may reed rotary engines rotary sporttimed Medallion race-timed Tee Dees now also two different balance systems use original smile counterweight cut back shaft new competition balance system originated Tee Dee RIC now used Killer Bee Venom Tee Dee Helicopter engine used Light Machines Glow Heads Three types use Cox Most common standard-compression bead found Babe Bees Ready-to-Fly RTF engines second head identical internal configuration extra cooling fin use Texaco engines Finally high-compression head used Tee Dees Killer Bees Venom also variety outside manufacturers make special-application heads such GloBee Galbreath/Nelson Davis Diesel RIL diesel conversions beyond scope article get specials Backplates reed engines have choice two backplates four different tanks have needle valve reedvalve system built standard RTF backplate features small venturi screen over back prevent large bits junk jamming reed valve backplate developed Killer Bee variation features beveled intake no screen bigger-bore venturi special chamfer just under reed valve smoother flow RTF version works great low nitro big props Fuel draw easy starting maximized running engine fast however venturi must opened up allow air flow higher velocity air helps maintain good fuel draw though Killer Bee opening made large possible starting needle sensitivity somewhat worse RTF version Fuel Tanks Fuel tanks may metal plastic long short have vents Stunt free fught Babe Bee tank short metal has free-ffight venting Black Widow tank long metal has Stunt venting Texaco tank long metal free flight vented Dragonfly tank plastic very large Stunt vented has clunk fuel pickup aerobatic RC flying basics put together useable format chart gives characteristics engine presented hope background enough prepare Part II Running Ruining Fixing Hopping-Up Cox engines odel Aviation