Brodhead Pietenpol Association

Original Posted By: DXLViolins
Subject: Pietenpol-List: Airframe mods>Hello to the group!> I'veenjoyed the discussion quite a bit, and the different>opinions..> Many feel Bernard's design should remain intact, others gladly>acknowledge it is overbuilt, worthy of modification such as 3 piece wing,>and the newest seen, addition to the vertical stabilizer when a>lighter power unit is employed.> I must admit I've never ben a purist!>..and I have a Subie engine on hand..>>Question..> Has anyone taken the time to compile a collection of mods>successfully implemented that were of significance?>>Question for the Model A builders..> What is the bore, stroke, compression and cam timing of the>venerable Model A ?>>Modifying crankshafts of existing engines always has an impact upon their>reliability.. It occurs to me that a re-ground camshaft could develop mre>torque at lower RPM and effectively put a clamp on high rpm capability>which apparently ends up as prop tip stall.>>I would think Bernard Pietenpol employed the Model A engine because of>it's known reliability and principally it's availability.>>If I'm correct in that assumption, it would only follow that there is not>much utility in extensive effort applied towards engines such as the Chevy>II 4 banger, as THEY are now rare.>Subie's now everywhere!>If a domestic engine is the criteria, there are millions of the 2300cc>Ford 4 bangers around. They are not a bad engine, in my opinion.. Most>troubles I've seen with them related to accessories that would not be>usedin an aircraft powerplant adaptation.> A specification comparison could be of great value..>>Regards,>Rich in the teeming metropolis of Santa Margarita>>________________________________________________________________________________

Original Posted By: Jim Wright
Hello to the group! I'veenjoyed the discussion quite a bit, and the differentopinions.. Many feel Bernard's design should remain intact, others gladlyacknowledge it is overbuilt, worthy of modification such as 3 piece wing,and the newest seen, addition to the vertical stabilizer when alighter power unit is employed. I must admit I've never ben a purist!..and I have a Subie engine on hand..Question.. Has anyone taken the time to compile a collection of modssuccessfully implemented that were of significance?Question for the Model A builders.. What is the bore, stroke, compression and cam timing of thevenerable Model A ?Modifying crankshafts of existing engines always has an impact upon theirreliability.. It occurs to me that a re-ground camshaft could develop mretorque at lower RPM and effectively put a clamp on high rpm capabilitywhich apparently ends up as prop tip stall.I would think Bernard Pietenpol employed the Model A engine because ofit's known reliability and principally it's availability.If I'm correct in that assumption, it would only follow that there is notmuch utility in extensive effort applied towards engines such as the ChevyII 4 banger, as THEY are now rare.Subie's now everywhere!If a domestic engine is the criteria, there are millions of the 2300ccFord 4 bangers around. They are not a bad engine, in my opinion.. Mosttroubles I've seen with them related to accessories that would not beusedin an aircraft powerplant adaptation. A specification comparison could be of great value..Regards,Rich in the teeming metropolis of Santa Margarita________________________________________________________________________________