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P-51 Foam Wing: Are Spars Necessary?

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P-51 Foam Wing: Are Spars Necessary?

Old 07-29-2020, 11:38 AM
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mark IX
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Default P-51 Foam Wing: Are Spars Necessary?

I am about to start sheeting the foam wing cores for my 69" ws P-51. I am wondering if the wings need spars added for strength? I was going to add to each panel, (2) 1/4 x 3/8 spruce spars, top and bottom, from the root to the tip, as you would do on the plans for a built-up wing? Is this overkill?

Thanx, Mark
Old 07-29-2020, 06:39 PM
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Outrider6
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Just my opinion, without engineering calculations, but I think spars would not be necessary on a sheeted foam wing. Over the years, there have been lots of such wings flying just fine. For example: SIG Kougar and King Kobras have sheeting only, with no spars. Adding spars would add complexity and weight, with just a little gain in strength that isn't needed.
Old 07-30-2020, 11:18 AM
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mark IX
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This is kind of my feeling as well. But this being my first foam wing, I wanted to get opinions with other experienced builders, thanx.

Mark
Old 08-01-2020, 09:13 AM
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mark IX
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So I guess I only need to add spars in the retract area, around the wheel openings, etc. There must be a tutorial about this.
Old 08-04-2020, 09:12 AM
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You need to add servo rails for ailerons/flaps and anything like wing tube sockets if applicable. Here is a buddy of mine holding my wings.

Bob

After sheeting

Before sheeting

Last edited by sensei; 08-04-2020 at 09:17 AM. Reason: Cirrection

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