On Sun, 16 Sep 2007 15:15:25 -0000, Tina wrote
in . com:

As best I can tell, it seems for a given configuration air speed for
best glide angle (I will define best as most shallow angle) changes
with weight, but the angle itself doesn't change much.

That's essentially correct. Parasitic drag increases with an increase
in air speed, so the effect of increased weight to increase the speed
at which maximum distance is achieved in still air does decrease the
Lift over Drag figure some.

Hi performance gliders carry water to increase penetration into headwinds,
dump it to increase time aloft, but still go down about foot for every 20
some they move thru the air, don't they?

That is approximately true. But any sailplane worthy of the name has
an L/D of thirty to one or greater with the highest performance
sailplanes today in the fifty or sixty to one range.

I need, for a fictional piece I'm writing, an efficient long range low
power consumption airplane and don't want it to fail because of
technical errors.

It is unclear exactly what sort of aircraft you need. Are you
referring to an actual aircraft that exists in today's world, or a
fictional aircraft? How many seats does your aircraft need to have?
Are you looking for a certified aircraft or will something excremental
do?

Here's the ultimate:
http://www.nasa.gov/centers/dryden/n...-068-DFRC.html
This aircraft is designed to remain aloft for months without requiring
any refueling, nor any fuel at all.

Thanks for your comments

You're welcome.