I'm looking at the Aeronca C-3 Collegian, which had a Clark Y airfoil, and I'm finding the following:
- Wing area: 142 ft²
- Empty weight: 466 lbs
- Payload: 470 lbs
- Stall speed: 38 mph
When I do the math for that wing area, a gross weight of 936 lbs, and a stall speed of 38 mph, I get a coefficient of lift of of about 1.8; that's higher than I see from either simulations or wind tunnel tests.
I'm inclined to trust these figures, since they line up with pilot reports on the C-3, and the airspeed range would be very narrow if the stall speed were higher; could it be that distortion of the fabric results in a later stall? The little I could find on the subject doesn't suggest any such effect. What's going on here?