On Sun, 27 Feb 2005 21:14:25 GMT, "Julian Scarfe"
wrote in ::

"Larry Dighera" wrote in message
news
While your statement above is generally accurate, it's not absolutely
true (as was pointed out to me by a glider pilot in e-mail). Here's
some empirical evidence of L/D changing with a change in weight (note
the right hand polar graph under 'Technical data'):
http://www.dianasailplanes.com/szd55.html

The data there indicates an L/D of 51 at higher weights, 49 at lower (about
50%). That seems consistent with the idea that at higher Reynolds numbers
(in effect, higher speeds) the skin friction drag coefficient reduces a
little.

Reynolds number: http://aerodyn.org/Frames/1flight.html

Given the "clean" design of the glider, the increase in parasitic
drag at higher speeds is probably insignificant compared to the "skin
friction drag" reduction.