> what is the means of propulsion when "gliding"?

Ever ridden a bicycle downhill? And no, it's not a perpetual
motion scheme. One design I know of uses the pressure and
temperature difference between the surface & the deep to pro-
duce a phase, hence volumetric, change in a substance to con-
trol buoyancy.

This has already been done, more than once. I'd look around a bit
before writing research proposals. Better explanations than mine
are out there, too.

www-pord.ucsd.edu/~rdavis/publications/4Gliders.pdf

Which, by the way, is the 4th link on the Google reference I posted...
-- 
http://www.piclist.com PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist