A problem I can see is given that hangar plots at airports are usually
rectangular-shaped, you usually try to maximixe use of the land and
squeeze in as many hangars in as you can, with walls adjoining one
another. Round hangars will waste a lot of ground surface area around
them.

I'd rather see a standard rectangular-shaped hangar, but perhaps built
with this stuff for the exterior walls and roof:

http://www.agriboard.com/brochure.html
http://www.agriboard.com/pdfs/tornado.pdf
http://www.agriboard.com/fires.html