I would guess toward the lower end (15:1) as an initial guess.  I do believe that a freewheeling prop should give a HUGE improvement in glide range over a windmilling prop driving the engine.  Look at the force/power required to spin your engine at the windmill rpm through the PSRU.  Then look at the tiny force/power required to spin the prop alone if it is freewheeling.  Now, with that differential in power required figure out how much force (drag) it takes to equal that power at glide airspeed.  The difference could nearly be like having the belly board down.  The difference between engine at idle and engine dead IS like having the belly board down.

Hard to verify.  Nobody has much experience with freewheeling prop.  What few data points there are might be suspect on account of the guy too real busy flying to get good data.

How many people COULD test that condition? ... Jim S.


Tracy Crook wrote:

Happened 2 days ago.  I agree that this is optimistic on glide ratio.   The starting point and altitude fix were done under the heat of handling the power failure.  The end point was based on an estimate of how far the landing was from Leesburg airport.   The glide ratio could have been anywhere between 15 and 25 depending on how close these estimates were and wind speed & direction.  Not bad even if it were at the low end of this range.  My RV-4 is only about 10 : 1 glide ratio with engine out.

 

Tracy

----- Original Message -----

From: Perry Mick

To: Rotary motors in aircraft

Sent: Monday, December 20, 2004 3:31 PM

Subject: [FlyRotary] Re: George Graham glide update

20 miles from 5000 feet.
That is 105600 ft / 5000 ft, or a glide ratio of 21.12 to 1. That's a little
difficult to believe.
I think the LEZ has a published glide ratio of 13 to 1, but I still assume
10 to 1 in an actual engine out condition. He must have had a good tailwind
or maybe some thermal activity?

Is this something that happened long ago or recently?

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