The Murphy Builders Site

I did some max power engine runs the other day and was disappointed to only
get 4300 RPM static. That's only 2038 RPM at the prop. I know I should get
some more RPM once I'm moving forward. Any ideas how much more I can hope
for? Assuming it's only a couple hundred more RPM that puts the engine at
4500 and the prop at 2133 which is 0.70 MACH at the prop tip. Max prop
thrust needs at between 0.88 and 0.92 MACH according to my web surfing. My
question is if that is enough to safely accomplish first flight? Judging by
the accelleration during my recent high speed taxi tests I think it will be
fine and I can try to address the low max RPM over time. A little over 2100
prop RPM just seems really slow for takeoff. By the way, 4500 RPM gives me
about 380 HP and well over 400 ft-lbs of torque.

Mike
044SR




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