Interesting results! I occasionally switch my engine off during landing
(just as I flare). This greatly reduces the landing roll and need for
braking. I only do it when I am landing in a very short field. So its
interesting to hear you think the GR is the same engine idle and engine off.
Jerry
LTS@avnet.co.uk
www.avnet.co.uk/touchdown
----- Original Message -----
From: "Dave DeFord" <davedeford@home.com>
Subject: stopping the prop
> 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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