Foam Ribs
 

I saw a kit that was built but not covered yet. It had blue foam ribs with balsa sheeting and cap strips.

What kind of foam would be good for ribs? Could I use the blue foam insulation from Home Depot?

How is thw weight/ strength compared to balsa ribs?


Thanks,
Gregg

Structures
 

Like most composite structures, wings built this way only use the foam for shape, not strength. The strength comes from the combination of a spar, the wing sheeting, and the cap strips tied from the spar/leading edge to the trailing edge. Normally, white foam is strong enough for this structure. Typically, white foam is 1lb density. blue is 2 lb density, and pink is 6 lb density. (Blue and pink are good for making plugs, but usually a little heavy for flying parts.)

To give a proper answer to your question, we'd need to know details of your particular design, but the above is a general guidline. The Lanier "Stinger" was built the way you describe, but with a solid foam core. On most designs of that type, you can safely remove the foam between the ribs with a hot wire and still have enough strength.

Foam ribs
 

You might find this of interest!http://content.communities.msn.com/i...te&ID_Topic=10


Chuck