Jim wrote in message . ..
On 28 Jul 2003 20:43:34 GMT, (B2431) wrote:

A U-2 constructed of lead would have the same glide ratio as one
constructed of balsa wood. It would glide faster, but just as far.
vince norris

Say what?
Dave


Within limits, weight has no effect on glide ratio (or Lift/Drag,
L/D). As has been mentioned, the speed that the plane achieves that
glide ratio goes up, by a function of the increase of the wing
loading. My glider (an LS6-b, a racing 15 meter glider) carries over
300 lbs of water for strong days - which increases my wingloading from
about 7.5 psf to over 10 psf. Wet, my average cross country speeds go
up about 10 mph (this is when lift is strong and consistent). My sink
rate goes up a bit, but in strong thermals (average acheived rate of
climb of 400fpm or more) the glide speed increase is worth it.

And of course, when the lift gets weak, we dump the water and creep in
- at up to 40/1, in my case!. Using a conservative 30/1 L/D, you can
go a LONG way from 17,999ft!

There is also a small theoretical increase in performance due to the
increases Reynolds number at the higher speed, but this is perhaps .5
to 1 L/D point.

Basic aerodynamics, guys!

Kirk
Phantoms Phorever, but real planes don't need no stinkin engines!