On Mar 17, 8:46 pm, cavelamb himself wrote:
Rip wrote:
wrote:

Actually I'm interested also to know if any other designs besides BD
aircraft utilize wing spars that are made of aluminum tube.

So if you know of any I'd like to know what they are.

Grumman Tiger, Cheetah, et al.

These are outgrowth of Bede.

Dan Denney I think used a custom center web tube extrusion, a tube
with a center web essentially.

Who used D-cell (not the battery, a shaped forward airfoil section)
spars?