RE: LittleSquare finally earns its wings!

From: John Barker <john.barker783_at_ntlworld.com>
Date: Tue, 5 Dec 2006 21:49:31 -0000

Hi Gary
So sorry to hear that you have fitness problems. I have two colleagues in
my own club who are diabetic so I do realize what a troubling ailment it can
be in many ways.

I don’t think that I was very clear in what I said about backing off turns
and, at the moment, I can’t think where the references are to put some meat
on the bones of the following statements.

Assume a motor takes 1000 turns, that it is fully wound, and then 200 turns
are backed off, leaving 800, and the aeroplane is then flown. The motor
will have a certain initial (flying) torque and will follow a certain
unwinding curve.

Assume now that the motor is wound to 800 turns and the aeroplane is then
flown. . The initial (flying) torque will be much higher, which is what
you don’t want under a low ceiling. The motor will follow a certain
unwinding curve, which is different from the unwinding curve in the back off
case.

Therefore, as the practical flyers have said, you use a heavier motor for
the low ceiling, back off turns to get rid of the troublesome high initial
torque and cruise for longer on the greater energy stored in the flat part
of the torque curve.

If you sketch some winding/unwinding curves you will see the difference
between starting the flight with (in our example) 800 turns on the unwinding
curve and 800 turns on the winding curve.

John Barker - England



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Received on Tue Dec 05 2006 - 14:05:40 CET