Luis Claudio wrote:

> I am torturing myself with the decision to build the instrument panel out of 
> aluminum or do a layup of glass and foam.

I think you'll find 1/4" plywood will be very heavy by comparison to
aluminum. It all adds up.  N891JF has a seat back made of 1/4" plywood,
and I figure I could save 4.5 pounds by redoing it out of foam and glass
like N56ML's seatback.  A leftover piece of 3/32"  aircraft plywood with
fiberglass on both sides would be much lighter, although could lack the
"structure" to even remain flat, unless you fold the glass over at the
bottom 2"-2" to give the thing something to keep it straight.  This
lower lip also helps to eliminate the cut hazard of the bottom of the
panel, as well as provides a very handy shelf on the forward side to
mount a bunch of stuff that you don't even know you need yet, like a
terminal strip for power and a ground bar for all the ground points to
connect to one place.  And there may be relays, timers, etc. added on

Aluminum is a better choice though, although it is more difficult to
modify later, often requiring a redo.  I had my first panel waterjet
cut, but on N891JF I started with one that I'd previously bent up, cut
it down to shape, and put a layer of carbon fiber on it to make it look
nice.  I doubt that it weighs anywhere near 4 pounds....probably more
like 2 pounds. Adding a lip at the bottom is more problematic with
aluminum, as it requires a bending brake (a sharp corner may simply
break off), but a local sheet metal shop can do that in about 5 minutes,
most of which is setting up the machine with the appropriate radius
dies.  Really, the more radius the better, from a crash protection

See for how I made the N891JF panel
with carbon fiber covering.  All holes in the aluminum were drilled or
cut with a jig saw, except the round instrument holes, which were cheap
hole saws from Home Depot (they cut aluminum just fine).  If you ever
want to redo it,  you can make new cutouts and recover with carbon fiber
for a new fa├žade. Another simpler option is to just cut big square
pieces out and install new ones with a different configuration, like the
panel Herbert Furle did on his KR panel, flat panels in aluminum (see for that site). See Steve Anderson did a
similar one.  See for
that one.  There's a lot of flexibility in this method, especially if
you're not going to have access to the back of the panel!

Mark Langford, Harvest, AL
ML "at"

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