Control Line: Speed

CONTROL LINE SPEED BACK IN THE SEPTEMBER issue Model Aviation told about John Bishops tip help balance big SuperTigre 2500 3000 engines John told prop driver large aluminum disk prop bolted against has heavy side should oriented crankshaft reduce engine vibration imbalance weight totals several grams Johns friends calculated produces pound radial force 8000 rpm orient drive washer correctly mark heavy side put shaft mark lined up crankpin exactly opposite crank counterbalance got letter Ken Bell modeler Fontana Wisconsin says its also important orient heavy side brass split collet same way collet locks prop driver plate crankshaft tighten prop nut has slot side might think such slight difference wont matter gram helps Im happy pass little suggestion like might make engine operate betterthere may similar methods would help Speed engines too times Speed Control Line Free Flight RC engines just refuse run properly instance friend flying small RC airplane couple years incident Suddenly just wouldnt work right anymore engine wouldnt run steadily wouldnt respond needle-valve changes wouldnt idle first thought engine worn out thats rarely case problems arise suddenly January1996 143 Chris Sackett has promoting 21 Proto Speed class models would judged beauty well speed Built small speed Tom Blankman displays Class 21 Sport Speed models flew Indianapolis Excellent Pilot Billy Hughes regularly flies other competitors ph crew fiancd Lori Wilson helps out Tom Blankmans neat little 21 Proto model features wing mounted wheels orange-checkerboard finish problems like occur suddenly its good idea have standard procedure steps try isolate problem four easy things try before buy new engine disassemble old First check fuel old have left cap off jug fuel could absorb moisture air Its nasty habit lot fliers have high-humidity weather can ruin fuel quickly its left open results sick engine runs overheating try some new fuel Next try new glow plug Sometimes element will oxidize bend out shape long before will burn out Check fuel lines replace new tubing necessary fuel line hole will allow air bubbles mix fuel produce surging unsteady running Finally remove needle valve make sure isnt chunk crud blocking fuel-feed hole four procedures take few minutes youre lucky may solve problem checks dont help youll need look something else times have found leaky crankcase cause poor needlevalve responsetwo-stroke engines must have sealed crankcases order run properly loose leaking backplate gasket common problem will show up now have seen few backplates holes through aluminum Oge-Willoughby race team recently lost out because two engines bad backplates newer Speed engines have 0-ring seals backplate prevent leaks Check backplate screws gasket loose head leaky head gasket leaky glow plug will also result erratic operation Check head screws check jointsquirt fuel look bubbles turn engine over should before Speed flight change glow plugs change glow plug gasket too Throw old gaskets awaydont reuse copper work-hardens might seal again loose leaky glow plug deadly Speed engine center post can turn red hot cause meltdown course RC fliers use carbureted engines leaky worn-out carburetor can precipitate same symptoms times vibration will shake barrel carburetor body enough wear outlong before sleeve piston other vital parts engine Some manufacturers use harder aluminum such 7075-T6 anodize parts reduce wear new different carburetor might wonders old engine can look crankcase carburetor leaks pressurizing crankcase tire pump squeeze bulb applying fuel soapy water places might have leak Use pressure fitting get air case either through backplate through blankoff plate clamp carburetor Youll have rotate crankshaft get air casewhen intake open piston should blank off exhaust opening will get some leakage out front bearingthats necessary because oil fuel lubricates front end carburetor leaks excessively replace Getting back some technical information Ill expound bit stabilization metals modelers experimenting making parts engines machining various alloys have ever machined anything have undoubtably encountered part warpage removed metal Most metals especially wrought-aluminum alloys such 6061T6 2024-T35 7075-T6 have built-in stresses rolling heat treating relaxes moves around machine off outer layers want end up precision part should stabilize metal work following procedure called Heat Treatment Maximum Dimensional Stability Nonferrous Alloys taken issue Machine Design magazine 2024-T35 Aluminum Rough machine 3650 F 8 hours air cool semifinish machine 3750 F 2 hours air cool finish machine cycle twice l0OO F 2100 F hold 20 hours 2000 F lap hone 356 Cast Aluminum 10000 F 2 hours water quench room temperature 24 hours 3100 F 4 hours air cool rough machine 2800 F 1 hour finish machine 2000 F 20 hours lap hone have used procedures engine parts Ive made really help achieve good finished dimensions Roundness pistons sleeves critical need stable material before finishing Carlos Aloise maker ACE record-setting Speed engines told 40 millionths inch out round enough slow down 10 miles hour normally use laps finish sleeves pistons get round going explain construction laps column ran out room would good subject whole column maybe next time uary issue RC Hero 40 Joel Cimmino ar 13 Texaco 1¼2A George Niebauer Pattern World Champs Ron Van Putte Scale Masters Jeff Troy KRC Electric Fly Bob Kopski Bamboo Sailplane Wayne Lehman How Transport Models Joe Beshar Read modelings comprehensive coverage issue Model via tion 144 Model Aviation