The knot unwinding torque change probably occurs every flight on any model. This problem does not occur for all models of the same class, indicating to me a stability problem, which I have rectified by moving the CG forward.
Bob
----- Original Message -----
From: dgbj_at_aol.com
To: Indoor_Construction_at_yahoogroups.com
Sent: Monday, February 26, 2007 10:11 PM
Subject: Re: [Indoor_Construction] Is this stalling? Or something else?
Someone mentioned, and I second, that unevenness in unwinding torque can
cause the propeller to pause, resulting in a drop. I have seen this in places
where there was no opportunity for a downdraft from an air vent.
Doing torque tests, I noticed that the unwinding torque was not a smooth
curve. When a knot unrolls, there is an abrupt change in torque. Sometimes an
unevenness in the twining of the two strands will result in a larger than
usual knot. It takes extra torque to form the knots, some take more than
others. Some unroll more uniformly than others. I found that the same knot
unrolled every time at the same number of turns, so if you see this at the same
place in the flight pattern, that is evidence supporting the idea that it is
unrolling knots causing the dips. If you separate the strands between windings,
you may change the knotting pattern.
If the plane is barely flying at the edge of a stall, a small change in
torque can produce a fall.
Gary Hinze
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Received on Thu Mar 01 2007 - 10:29:51 CET