Re: Re: Testing props

From: <dgbj_at_aol.com>
Date: Tue, 1 May 2007 03:46:10 EDT

For a slow moving prop, you can count and time turns during flight. At
fixed intervals during the flight, count and time ten turns. Divide ten by the
times to get revolutions per second. Do this ten or twenty times during the
flight. Record the time of each measurement. You can then plot revolutions
per second vs time. Draw a smooth curve through the points. Now you can
integrate the curve to get actual turns expended at each point in time. Check to
see if the total turns is consistent with the turns actually used; turns
wound in less turns remaining on landing. If off, pro rate, or repeat with more
sets of measurements to get a finer cut. Now with turns against time known,
use your unwinding torque curve to get torque vs time. From a level flight
test, you can then tell exactly the time the plane reaches level flight, the
length of the ascent and the length of the descent.
 
Gary Hinze



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Received on Tue May 01 2007 - 00:48:48 CEST

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