Originally Posted by
Captcrunch44
Question here.
Why do we keep the RPM’s below 10000. I understand that torque is for pulling the stump but RPM’s keep it moving.
Originally Posted by
the Wasp
so, with that above, according to OS, we should be running our engines on the ground around 8500 (even lower), so in the air our engines will unload around 9500/10,000
Jim
Originally Posted by
Captcrunch44
Wasp
thats a great article on power. I need to I adjust my thoughts on under propping engine’s. I keep thinking that some people are over propping there engine’s. Witch i have see in two strokes a lot, however 4 strokes like a little more prop. Also until the last few years i haven’t been running anything bigger then a 56.
So thanks to all for the attitude adjustment.
Unless one wants to limit their flight envelope to hovering, I don't understand the logic of some guys propping a model aircraft engine at or near maximum RPM static. That would be like having a 6500 RPM stall convector on a street driven car with a mildly built SB Chevy.
In a slow airframe with lots of drag, I might prop for 9000+ RPM static with a medium block Saito. On something that is "slippery", I want more RPM cushion for the prop to unload without over revving as the speed increases. I typically prop my big block Saitos for 7500-8500 RPM static. Medium blocks I want another 1000-1500 RPM depending on the airframe.