Has anyone ever used luan plywood instead of lite ply for fuselage construction ? Seems light enough, from the stuff I've used in the past for non aviation projects. Seems a cost effective substitute. Am I wrong here, or just cheap ?

Yes indeed to your question. In my years of electrical contracting I have done many a dumpster dive. My stash currently includes 3 sheets of Oak veneered 1/8 inch ply. Makes really nice parts. Recently had a housebound club member cut me a short kit for an Aquila, and using this ply and carefully selecting the balsa it should build out lighter than the Airtronics kit.

If the ply's are of equal thickness I'd use it, if not no. I once made an acceptable 15' canoe out of the non-equal Luan but I glassed it inside and out.

Ed Slobod specified this material in the RCM construction article for the Paragon. In my experience, it is made with a weather resistant glue and is very durable.

At the local Lowes, and Home Depot, I found (labeled) 5.2 mm luan plywood. Actual measurement was just at 3/16". Too thick and heavy ? It goes for $6.47 for a 2 x 4 foot sheet. I'll pick up a sheet tomorrow and see what shakes loose.

or actually, maybe I should consider continuing to look for actual 1/8 inch stuff

Home Depot or Lowes should also carry a product called "Door skin". It is slightly less than 1/8". That is the material I referred to in my previous post about the Paragon.

Lowes and home depot probably can't get it, but most real lumber yards can order 1/8 Italian bending poplar. I usually buy three sheets at a time.

Mark

I've seen some kind of light plywood at Home Despot that seemed like it would be nice for making planes, if slightly heavier. It was very pale. Aspen, maybe?

If you want a true structural equivalent to the usual light ply, use bubble gum with a few wood fibers as reinforcement. Or find some fruit crates.

If the luan has 3 equal plies, it will NOT be very stiff or strong across the grain of the face sheets. 4 layers is ok. The normal thin face plies and thick inner ply are more closely matched in terms of directions. Either one might be more appropriate, depending on the application.

OK... So I didn't go for the 5.2 mm (3/16") from Lowest/Home Depot. Still trying to find local supplier of 3mm (1/8"). Also..... What ever happened to spruce sticks!?!?!? Tried a couple LHS's here in San Antonio, and was amazed to find NONE !!! Guy behind counter was useless, as well. Didn't even know what spruce was!!!!!

I used to buy this stuff for making forms. The actually make two different versions , one for bending along the 8 ft dimension and the other for bending along the 4ft dimension. apparently it's a balsa wood core and Poplar for the two skins. Did not get along the Laser I had back then

Jim