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Old Dec 27, 2012, 12:59 AM
George Shering is online now
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[QUOTE=Golikov;23621083For example, some known to me propellers have a maximum efficiency at the blade angle of attack of about 6 degrees. And to increase the angle of attack to 9 degrees, prop does not stall. But does accelerate just less effective. You spend more energy. In order to achieve the same result on the speed and altitude.

how big is the difference, say from 6 degrees optimum to 4 degrees on one side and 9 degrees on the other?
A long time ago I ran the RFM 15x16 through Martin Hepperle's program and indeed the efficiency curve was very peaked, falling of rapidly from a maximum of 80%.
This was a Hannes Delago design I believe, may be wrong. It was extended by Rudi to the RFM 16x17 slim which can be very effective, but only in certain conditions. But I forget the exact efficiency curve.

Both you and Joe are right, it is the rpm v. forward speed that matters, but the thing we can change is the controller PWM ratio, hence the power, hence the rpm. The rpm could be controlled, like in helicopter governor mode, but this is probably beyond the processing power capability of the ATMega and 8051F processors used in today's controllers at F5B rpms.
Now if Steve's new controller above uses an ARM Cortex controller then we are talking business!
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