"Holger Stephan" wrote in message
...
Kevin Horton wrote:
Note 2: the glide ratio does not vary with gross weight. I won't try to
explain the math or physics as there are lots of references available on
the web for your googling pleasure.

True only in theory (i.e. on high performance gliders). The added drag
with
the increased max glide speed will decrease the ratio.

From what I have been taught (and teach my students) Kevin is quite
right. Just because glide ratio (best L/D) does not change, that does not
mean that the aircraft performance is unchanged by gross weight. At a
higher weight, best L/D comes at a higher airspeed. If you happened to be
downwind of your intended landing area, you would be better off (very
margionally) by hanging on to the extra weight. As already mentioned, stall
speed decreases with weight and using that same formula (1/2 MV^2) reducing
the velocity on an off-field landing drastically reduces the energy that
must be disipated after landing.

On balance, I believe that fuel dumps in small aircraft are a bad idea.

Vaughn



- Holger