In anticipation of getting glider wings in a few months, we did some
experiments in our XS (with 912S and Whirlwind prop). With the engine off,
we had to slow down to 55KIAS to stop the prop from windmilling. A dive to
120KIAS was then required to restart the engine, without using the starter.
Just about ideal behavior (short of full feathering) for motor gliding.
While we had the prop stopped, we also checked the glide ratio. We measured
10.6 at 65KIAS, which was identical to the value with the engine at idle.
Weight was about 1280 pounds. I guess the engine puts out just enough power
at idle to overcome the increased drag of the rotating prop. It would be
interesting to know the glide ratio with the engine off, and the prop
windmilling, but we didn't do this test.
Dave DeFord
N135TD
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