Fred,
"Pretty much everyone who fly's classes with slow moving props uses a VP
where allowed and extreme flaring props where not allowed so the curves would
not be representative of the true torques."
The curves constructed as I suggested would be the true torque at each point
in time. Your torque versus turns curve relates torque to unwinding turns.
The integral of the revolutions per second curve, taken from an actual
flight of the airplane, is a turns curve, relating unwinding turns to time.
Combining the two gives a torque versus time curve.
"Most use a rowing stroke watch for RPM measurement but the true reading of
prop and rubber efficiency is the flight time."
Thanks for the tip. I was going to use two watches. Hard to do with all
the measurements I will be taking and equipment I will be carrying around.
Overall time is not a good measure of prop efficiency, especially if you
want to use a variable pitch prop and need to know and optimize prop efficiency
at each point along the trajectory. Even with a fixed pitch prop, it would
be good to know what the efficiency is at different parts of the trajectory.
You might want to optimize the prop efficiency for the high end of the torque
curve, because that is where most of the energy is found.
"I was thinking we need a computer class where we enter values and the best
computer simulation wins, this would be for the non flying science and math
guru's."
That would not be much fun. Too easy. Just put in a high rubber specific
energy and a low sinking speed.
Gary Hinze
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Received on Tue May 01 2007 - 18:58:39 CEST