Candice,
Is there a reason you are using plywood? BD-4's are being built every
day with aluminum bonded to the outside of aluminum structure with
Proseal adhesives. WWW.bd-4.org will get you into their site. The
latest is the bonding of aluminum sheet to ribs as a finished surface
with only rivits on the trailing edge. When they want a covering to be
removeable it is fastened with an bolts and nuts directly to the angle
structure. If you are using tubing and penetrating it for bolts I
would be concerned about weakening the structure by the penetration of
the bolts. the tightening would also distort the tubes. Depends on
your structure. Jim Bede did a paper on the strength of fastener types
that is also available on the website. good luck with it and have fun.


Dean B.