Balsa plywood

LAST EDITED ON Oct-13-04 AT 03:17 PM (CDT)
 
A friend gave me an old airplane. He said the airplane was given to him. I noticed this airplane is probably scratch built because the entire airplane is built from 3/32" balsa including the elevator, fin, stabilizer, fuselage, ribs. The stab, fin, elevator are 3 layers of balsa glued together like plywood with the wood grain 90 degrees to each other. Fuselage is several layers of balsa glued together too. Seems like a lot of work. Is this something people use to do to try and make an airplane more ridgid? Did anyone every make kits like this?

I compaired the wood on the fin, stab, elevator to 1/4" balsa and I can see the plywood stuff is not as flexable as the 1/4" balsa. Old dried out wood is probably not very flexable anyway.

The person who taught me that technique called it "balsa plywood".
Plys of Balsa glued together for greater strength.

Why would anyone use that technique? Hhmmm....
strength? Stiffness? Weight savings? Craftsmanship? Naaa...

The builder probably couldn't find the right size wood.

Iused that method for the "I" beam on a couple if "I"beam wings that I built. It is quite strong and reasonablky light. As for making fuselages that way,---- well, I think it would be overkill unless you were building for some of the old vibrating 60s on ignition.

Bigiron

Balsa plywood was a common free flight technique for strong but light models. Carbon fiber has pretty much taken it's place. Rudder and stab outlines on many scale free flgiht models are still laminated balsa using white glue or aliphtic resin type glues, not AC.

The balsa-plywood is available from one of the RC shops in California. Or it used to be. I have several sheets in my basement now. Have had for several years. Built a radio plane using the stuff. Came out very heavy. Might make good formers, but, I would not use it for anything else. Later, DOC

I remember getting some of this stuff. Can't remember who sold it to me, it was one of the mailorder balsa places. Well, yeah, it was heavy, mainly because the balsa used wasn't the lightest. The grain was all crooked, it wasn't the best balsa I'd seen, either. I suspect the veneer was rotary cut. The glue was also pretty heavy. All in all, pretty ugly stuff.

I just finished restoring a swap meet Streak. It wasn't bad (no signiture Streak tips was one omission, so I had to make some), but one weird feature was a very thick, plywood (real 3 ply or so ply, not balsa) rudder. It weighed a ton, so it had to go.

Easy deal, right? Just use the ply rudder to trace a new one onto nice balsa. Sure, except...

I ran the grain sideways, not up and down. This is fine for the first, skinny portion, near the canopy, but bad for the rest. Didn't notice it until it was glued on.

So...it's Balsa Ply Time. Yep, I got a piece of (I think) 1/16th balsa, and glued it to the offending, grain-the-wrong-way piece, grain going up and down this time. Sure, the fin now is a little thicker than stock, but kit (Top Flite) tailfeathers always were maybe a sixteenth too thin, anyway.

The whole thing, with Fox 29 Stunt, and a slightly longer than average landing gear strut, came out at 27 ounces, about par for the course, I think.