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Foam Ribs

Old 04-15-2002, 02:43 PM
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Default 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?

Old 04-15-2002, 02:54 PM
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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.
Old 04-20-2002, 04:19 AM
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Default Foam ribs

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