Hi Bob,
Thanks for reply.
I used IAS at 5 mph intervals from 70 to 85 and got an incredible smooth curve ( I couldn't believe it would come out so smooth). I used IAS because ground speed derived from GPS would not be appropriate. I don't know if you recall, but my plane has that great big pig sticker for a pitot tube, and is incredibly accurate (when measured against ground speed from GPS and corrected for temp and pressure). I flew successive 1000 ft descents, starting 500 ft above so as to allow adequate time and altitude to stabilize the decent. Here is the data:
IAS(mph) time to descend 1000 ft (min:sec) rate of decent (fpm) L/D
85 1:04 937 7.98
80 1:15 800 8.80
75 1:24 714 9.24
70 1:27 690 8.93
I really do need to repeat all this to verify it. You can see that from the above numbers that below 75, I am starting on the back side of the curve for L/D, though the min sink rate is still down there. Since I was alone in the plane, and the nose is so high when gliding below 70 IAS (no flap obviously) I was uncomfortable to fly slower without other eyes in the plane. Next time, I will try to do it when flight following isn't so busy and it is calm enough to do it again. I will try to do it at the same weight, so will have another body in the plane and less fuel to compensate. If I just add a person (weight) without compensating, the best L/D should increase (like carrying water ballast in a sailplane).
BTW, I got my glider rating in a 2-22 too, and I seem to remember the L?D (yes I meant ?) was about 16 or 17. The 2-33 was a nice improvement.
