Right, I messed up.
A 0.0641" sheet (2'x5') of aluminum weighs
9.3lbs according to the Machinery's Hand Book.
Sure it is like with like, as that is the skin of the a/c.
More research has turned up, 1/16" and 5/64" plywood and 7/16" balsa.
http://users.skynet.be/BAMRS/dh103/f...nstruction.htm
So as you say 8lb or a little less.