Hi Paul

Another suggestion of a nice product that can be used for the I-beam construction as well as for the spar

The attached photos are for two cool products made by nida-core

These are foam products one really dense and the second a little less dense and less stiff

What's neat about this core material is that they have glass fibers going though it and on the sides. As the second photo shows, the glass can be pulled back a bit so you can cut the foam back such that you can wrap the glass on all sides (double thick on the edges which is like instant reinforcement

For the ribs I would first cut the airfoil shape in the foam with the glass sides extending 2 or 3 inches beyond the foam

Then light epoxy the sides of the ribs but only to an inch away from the edges and allow to harden

Then when you are ready to add the skin, on the wing, you epoxy the edge (i.e. The last inch of the airfoil) plus the edge facing the skin (it will be double layer since you have fiber matting on both sides) and then put the skin on

I included the product name and company address. They used to be super responsive but a few years ago were bought out by 3M so may be harder to reach now

I believe the above described method will result in a super strong light weight structure (caveat : I never tested this but have good confidence in it). What this combo enables is the spreading of the forces across the entire rib all the way to the bottom of the rib as well as both sides

Ps if someone wants to partner on this and pay for materials. I am willing to make a few I beams and ribs over a couple of weekends as time allows

Simon Saba

Do you think the foam would be affected by gasoline as in a wet wing?

What does it cost?

Paul Lamar


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