Re: Alum instrument panel

Marc J. Zeitlin

Bill Allen wrote:
The authorities are suggesting that the alum panel (0.125" 2024T3) will be weaker than the original 5 ply BID (2plys one side 3 the other) and will thus need additional bracing.

Weaker? No. Less stiff? Yes. Although 1/8" AL is way overkill. As has been suggested here before, 0.062" or 0.090" AL is more than adequate. BUT, they MAY require stiffeners in the horizontal and/or vertical direction, especially on wider planes such as COZY's. You don't specify whether it's a LE or COZY.

... if you have, could you let me know how many attach points, any local beef up, and
if you have any "additional bracing" if you thought that the Alum was weaker than the 5ply bid original?

I suggest an AL "L" flange across the top of the leg holes, as well as around the top of the IP. This will substantially stiffen the IP. Build glass 5 - 6 BID flanges for attachment to the fuselage sides and center post, and connect with screws every 4" using nutplates on the flanges.

But there are many ways to skin this cat - I believe Burrall has described a similar method in the past, as has James Redmon, and a few others.

Marc J. Zeitlin                      marc_zeitlin@...
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