Pietenpol-List: reduction gearing and props
Posted: Sun Feb 03, 2002 10:09 pm
Original Posted By: Gary Gower
Fisherman,You have a pretty good understanding of propellor efficiency, it is truethat with a draggy airframe like a Pietenpol that you need to move alarge volume of air at a relatively low speed with a large disk area.With my Subaru engine, I have it geared down 2.35:1 which means at 3500engine rpm, the prop is only turning a little less than 1500 rpm. Ofcourse I have to use an 80 x 52 prop with a very wide chord of theblade. I am using a pattern that a friend of mine used, and his Subaruengine (not turbocharged as mine is), turned 4400 rpm at about the samefield elevation. Since my turbocharged engine develops it's max hp at4800 rpm, I expect that mine will turn up full 4800 static rpm here.A little more on the engine. I left the stock flywheel on and thenbolted the clutch plate in position so the clutch springs could absorbthe torsional impulses from the engine. Works like a dream, engine w/oprop at this stage is smooth as silk.John Dilatush, NX114D - Making the duplicating machine to make the propso I can go flying!Salida, ColoradoPS. There is a ultra-lite Newport replica flying with a motorcycleYamaha 1000cc engine that is geared down 4:1 through the stocktransmission swinging a huge prop. You can almost see the bladesturning at cruise I am told and count the blades at idle. Plane flysgreat!________________________________________________________________________________Date: Sun, 3 Feb 2002 20:46:23 -0800 (PST)
Fisherman,You have a pretty good understanding of propellor efficiency, it is truethat with a draggy airframe like a Pietenpol that you need to move alarge volume of air at a relatively low speed with a large disk area.With my Subaru engine, I have it geared down 2.35:1 which means at 3500engine rpm, the prop is only turning a little less than 1500 rpm. Ofcourse I have to use an 80 x 52 prop with a very wide chord of theblade. I am using a pattern that a friend of mine used, and his Subaruengine (not turbocharged as mine is), turned 4400 rpm at about the samefield elevation. Since my turbocharged engine develops it's max hp at4800 rpm, I expect that mine will turn up full 4800 static rpm here.A little more on the engine. I left the stock flywheel on and thenbolted the clutch plate in position so the clutch springs could absorbthe torsional impulses from the engine. Works like a dream, engine w/oprop at this stage is smooth as silk.John Dilatush, NX114D - Making the duplicating machine to make the propso I can go flying!Salida, ColoradoPS. There is a ultra-lite Newport replica flying with a motorcycleYamaha 1000cc engine that is geared down 4:1 through the stocktransmission swinging a huge prop. You can almost see the bladesturning at cruise I am told and count the blades at idle. Plane flysgreat!________________________________________________________________________________Date: Sun, 3 Feb 2002 20:46:23 -0800 (PST)