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 later. 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 standpoint. See http://www.n56ml.com/n891jf/panel/ 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 façade. 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 www.krnet.org for that site). See http://www.krnet.org/krs/hfurle/instruments.jpg. Steve Anderson did a similar one. See http://www.krnet.org/krs/sandersen/120604_060.jpg 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" N56ML.com www.N56ML.com _______________________________________________ Search the KRnet Archives at https://email@example.com/. Please see LIST RULES and KRnet info at http://www.krnet.org/info.html. see http://list.krnet.org/mailman/listinfo/krnet_list.krnet.org to change options. To UNsubscribe from KRnet, send a message to krnet-le...@list.krnet.org