CONTROL LINE SPEED JET TEST STAND jet engine test stand shown September issue does belong Jerry Thomas stated designed built Earl Baileythe manufacturer Bailey jet enginesfrom Houston Texas Earl did extensive testing model pulse jets before arrived design engine producing Jerry Thomas avid Jet fliers US borrowed test stand compare own thrust-measuring equipment pulse jet engines erratic beasts always operate way would like way think should good thrust-measuring device almost imperative fastest way test new design new modifications engine lapping get quite few letters some have some pretty good questions John Callahan Houston Texas several good questions thought could cover John others Houston area flying something called Four Start 40an event aimed get people started Pylon Racing can progress Quickie 500 other faster classes use nnged Super Tiger 40 engines John asked can lapped relieved reduce internal friction go faster answer definite yesmaybe Its complicated several factors enter Ill try explain best can Speed use lapped ABC engines almost exclusively forget rarely think about ringed engines still lot out good engines Ringed engines can improved proper treatment cylinder gain probably wont much can get ABC setup Such modifications can make engine run smoother cooler Most friction ringed engine comes ring lapping tapering sleeve will change very much biggest improvement can make get sleeve round piston round fit properly get minimum leakage past ring want experiment get some spare rings insert ring itself sleeve look through sleeve light see ring touches wall way around doesnt bend ring necessary until does Ill warn though might break some rings isnt easy getting ring off piston getting new have learn rings usually some kind cast iron too may brittle wont bend readily necessity tapered sleeve depends lot piston What piston alloy what piston clearance lot ringed pistons machined 2024 aluminum other wrought-aluminum alloy have large coefficient thermal expansion isnt enough clearance between piston diameter sleeve piston will expand bind gets hot Engine manufacturers learn quickly just much clearance need probably shouldnt have worry about look piston sldrt can see scuffed up rubbing binding against sleeve tapering sleeve will definitely help Some manufacturers use pistons machined castings now have alloy silicon less expansion less clearance needed pistons expand heat travel down during stroke lapping sleeve get round tapering give clearance bottom can definitely increase operating rpm Just dont expect much increase would get modifying lapped ABC engine because January1997 151 Fining minipipe 21 Proto can difficult Making top Ken Barthel built neat 21 Proto wing too far back half cowl removable eliminates problem noseheavy couldnt get off ground Ron Peters casts critical eye Bob Wilkies Nats D Speed model Formula 40 engine model features grandson BJ Snyder BJ father Blair side-mounted engine removable cowl Ft Wayne IN flew several events Turn great idea cash could worth $5000 PARThERS FOR PROGRESS new cash award program funded RADIO CONTROL HOBBY TRADE ASSOCIADON RCHTA help identify unique revolutionary prod ucts ideas will benefit fellow R/C modelers nationwide contest open individuals grand prize award $5000 will given best idea year chosen four periodic winners will receive $500 award official kickoff PARThERS FOR PROGarss will made October 18th during 1996 National Model Hobby Show Chicago first grand prize winner will receive check $5000 person during 1997 National Model Hobby Show Periodic grand prize winners names will published R/C magazines Get peer recognition Help others have fun just maybe win lot money process Enter ideas today Enter often like Got idea Use information below call write fax E-mail RCHTA office official entry form rules Phone Fax E-mail Address 847 526-1222 847 526-9987 rchta@lndcom RCHTA 560 Bonner Road Wauconda IL 60084 EUUEANI mm roducts/ideas submitted will become part o public domain See official entry form complete details rules contest havent eliminated friction ring type ring used makes huge difference friction Conventional rings compressed insertion sleeve have spring force against wall entire stroke Dykes rings like used K&B engines machined round cut narrow slitting saw depend compression combustion gases force ring against wall seal As piston goes down combustion pressure drops force against wall drops too rub during top part stroke can see effect look wear marks sleeve Again piston rubs too tight against sleeve tapering can reduce friction John also asked lapping compound should used get new ring seated wouldnt recommend usually takes two runs get ring seated enough engine starts readily shouldnt need abrasive would worry about getting abrasive creviceslike under ring can keep wearing metal away dont want get too much clearance between ring piston slot can lose too much compression John also asked dont make lap long sleeve wears taper would end up tapered sleeve just doesnt work way want short lap can remove metal want cant depend lap wearing correctly shape want sleeve end up diamond lap shaped correct contour would probably work would make much would cost lap too short good eitherit would too hard keep straight sleeve adjust tension pressure lap Its something have learn can feel cutting torque lap goes away have expand until cutting again sleeve gets too hot have too much pressure Keep lap wet oil-abrasive mixture dont let get dry go through chrome should strip sleeve taper rechrome hone lap again John wanted know could get book would tell him about lapping fitting etc told him thai dont know book tells very much about such things arent old experienced machinists left either Weve learned lot last couple years well keep experimenting Proto tips modelers building 21 Proto models easy build have few tips suggestions can make lot easier Make sure wing stiff Use hard balsa cover carbon fiber can Canadas Dave Ker told saw carve narrow groove edge way around centerline about deep Take some carbon cord stretch down groove around around until full let cyanoacrylate CyA glue penetrate set up Now have extremely strong edge wing have excellent line carve airfoil Carbon-fiber spars can also help stiffen strengthen wing Good soft basswood about best fuselage light carves easily difficult insert minipipe airplane assembled make removable top cowl like FAI Speed models have bolt down threaded inserts built fuselage exhaust gasses hot need heat-resistant deflector let out fuselage Pick up scrap lawn chair bent aluminum frame curved corners just right size deflector glue RTV silicone Consider upright engine design rather inverted crash wont wreck engine have facilities can get made make extension spinner backplate move forward about give room fuselage material ahead intake airplanes pretty nice paint job tiett1c Catalog #37 xsVJSpring 1996 e VI-o St l4eflW pctvtS Its Rubber Power Wonder 0tVfl Peck-Polymers Areographics Nowlen Aero West Wings Lee R/N Send $400 Catalog #37 New items 1996 PG Box 710399-MA 7Santee CA 92072-0399 Phone 619 448-1818Fax 619 448-1833 152 Model Aviation
