Dave Nadler wrote on 11/19/2020 6:59 AM:
On 11/19/2020 8:35 AM, Eric Greenwell wrote:
How odd the 63:1 only occurs at the high wing loading in 21M, and not at the minimum wing
loading, where the L/D is essentially the same for the 18M and 21M wings.

Not odd at all. Reynolds number changes make a big difference especially with tiny chord. IIRC
the original Ventus 15m increased LD 2 points with ballast, and could not change wingloading as
much as modern gliders.


This does not seem to be about wing loading, as the chart shows the 18/21 versions at the same
wing loading, so I repeat: It's still odd that adding 10' to the span does not significantly
change the performance at any speed except in the lowest few knots of the polar.

If it's Reynolds number that's important: Shouldn't the 21 M wing have more feet of wider chord
than the 18M wing, and shouldn't we expect it to do better, just based on that?

--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to email me)
- "A Guide to Self-Launching Sailplane Operation"
https://sites.google.com/site/motorg...ad-the-guide-1