Posted Saturday, October 24, 2009 @ 10:30 AM
Hi Ray,
The best way to get this information is to fly a couple of flights yourself at a representative weight.
I say this because, if you go back to the original French manual it says those figures were obtained 'with minimum fuel and no equipment'. Both Rene and his test pilot, Bernard Chauvreau are tiny guys, and I would reckon they did this in a brand-new airframe with minimal instruemnts, no radio or battery, no upholstery or interior trim, etc etc. There is no mention of what propeller they used either. A feathering single-blade propeller was once available, so they might have used that to get the best possible figures, or a very coarse-pitched one to create minimal drag when it's stopped. Your prop is probably different, and it may not stop exactly horizontal, which is the mimimum drag position. All these things will affect your glide performance.
Exaggerating the performance figures was very common among all manufacturers in the late sixties. You cannot believe a word they said, and particluarly in this case, since Rene was trying to get American certification for single-ignition on the basis of the airplane having a good glide (as he suceeded in doing in Europe).
When I tried it (very carefully, high up, on a calm day with no thermals, wave or ridge lift) the best I got was a little over 1:16 and about 500 fpm sink. I only flew at the book airspeeds rounded up by a few knots, but of course if those original figures were attained at such a light weight, then you should be flying faster if your airplane weighs more.
And I'll bet your ASI is no longer dead accurate.
This would be a good target to go for when you fly your RF4. Time and measure the height loss in some glides at 50, 55, 60 and 65 mph, plot them on a graph and you'll find out precisely how your own personal airplane flies when you are at the controls.
If you use any other numbers, you will merely have a computer program very accurately reproducing utter rubbish.
Go for it. Good luck, Bob