# Intrument Panel Thickness in Aluminum, Glass, and Carbon

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#### rv7charlie

##### Well-Known Member
re core materials: There'll be multiple holes in the panel; sounds to me like a fabrication nightmare to fill/seal the edges of every hole for adequate edge strength, and maintain precise sizing. Then there's the issue of instruments that mount from the back of the panel; they'll look quite recessed (even with restricted views when seen from an angle).

#### wsimpso1

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Well, if you are mounting to the composites, you cut out the core where things will be mounted, bevel the cut edges of the cores and layup glass-to-glass.

The preferred approach seems to be to mount the various hardware to an aluminum plate and screw the plate to the fiberglass. I am planning that way.

#### wsimpso1

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did you get the cad sorted out
I have been playing with it. Using a quarter ellipse, it did not transfer to .dfx, nor did changing it to a spline fitted to set of points. In desperation, I changed the shape to a bunch of points about 1.5" apart, and just ran straight lines between points. That went to .dxf just fine. Now to try it in Front Panel Express and see if I can retrofit the smooth curve.

Billski

#### rv7charlie

##### Well-Known Member
A little reality check might be in order. This isn't a spar cap, or even a wing rib. It could be a gram or three lighter by using 2024 bent into an angle, but it's certainly strong enough to hold a few pounds of radios. And there's no type certificate requiring compliance; in fact, I'd bet you would have a difficult time finding more than a few pounds of 'certifiable' material in the entire airframe of something like a LongEZ.

#### Toobuilder

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I did a radio restack on a buddys Cessna 337 and removed the angle rails that were swiss cheesed so badly through numerous radio reconfigurations that there was no possibility of re use. The "old" rails were these same sharp cornered, non identified alloy that looked suspiciously like the stuff in the Home Depot aviation isle. Some long retired A&P apparently decided that the scrap leftover from reflashing the windows of his hangar was good enough for this 337 years ago, and despite the fact that I made new rails of mil spec angle (because I had it on hand) I have to agree. I "hate" the thought of sharp corners on machined or extruded aircraft parts, but one has to consider risk and application. If the rail fails, whats the score on a THA (Threat Hazard Analysis)? Pretty **** low.

#### wsimpso1

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re core materials: There'll be multiple holes in the panel; sounds to me like a fabrication nightmare to fill/seal the edges of every hole for adequate edge strength, and maintain precise sizing. Then there's the issue of instruments that mount from the back of the panel; they'll look quite recessed (even with restricted views when seen from an angle).
Using the 18 pcf foam, most of us do not close out edges. It is pretty stout stuff by itself.

#### rv7charlie

##### Well-Known Member
Understand. It's often difficult for builders accustomed to one medium to get excited by a different one; that's probably why I'm more focused on aluminum. Flat, or flat-wrapped, to me aluminum seems a 'no-brainer'. Cut to shape. Scuff. Paint. Done. Now for wing tips, cowl, wheel pants (or swoopy Lancairish shapes) I get it.

Back to the 440 tray issue: I can't address how the actual 440 tray is made, but the 430 tray (which the 440 will fit) is designed for the sides to mount behind the panel and the bottom of the tray extends out *slightly* to reach the front of a typical aluminum panel (maybe 0.070"). The 430 faceplate is so close to the width of the tray that if you bring the tray forward to the face of the panel, the cutout in the panel may well show instead of being hidden by the faceplate. Point is, the Garmin'system' expects an aluminum panel. Insertion depth tolerance is pretty tight; failure to fully seat the radio often results in intermittent/flaky operation. If the 440 tray & faceplate are made just like the Garmin versions, then you may run into conflicting issues if the panel is much thicker than ~0.070".

FWIW...

##### Well-Known Member
Made an instrument panel recently for a friend.

Got the digital drawing and waterjet cut an 3/4" MDF template for the outside contour. Cut another stainless contour of 0.2 mm (0.007") with the instrument holes and the bolt holes. Filleted the corners with a 4 mm (1/16") ball bearing and 5 min epoxy.

Infused (but hand lamination would also do) a single layer of carbon in this. Then added another layer of 200 g/m2 carbon, then soric round pads that were 1" larger in dia than the holes.
I shaped foam (1/4" Divinycell HP80) in a triangular cross section as vertical stringers between the holes. Two more layers of carbon twill and infusion.

Drilling through the bolt holes is best done by placing a bushing on top of the "bulb" and using that as a drill guide. Positional accuracy was around 0.25 mm (0.01 "). Drill a hole in the bulb where the instruments go and sand out until the "bulb" is gone.

All in all we spent maybe 150 US$in material and were done in a few hours. Hard to beat in terms of cost or hours spent. #### rv7charlie ##### Well-Known Member I do get it that some are more comfortable working with composites. But if you have a waterjet and a sheet of aluminum, wouldn't you be 'done' when you get 33% of the way through the 1st step? #### proppastie ##### Well-Known Member Log Member But if you have a waterjet and a sheet of aluminum, wouldn't you be 'done' when you get 33% of the way through the 1st step? perhaps the plastic glues better to the plastic rather than the alum glues to the plastic. ....what I do not understand is why there is a .007 thick piece of metal in the assembly. #### dwalker ##### Well-Known Member perhaps the plastic glues better to the plastic rather than the alum glues to the plastic. ....what I do not understand is why there is a .007 thick piece of metal in the assembly. The way I understood it the SS was used as a mold/form #### Jsample40 ##### Well-Known Member Another alternative is to employ readily available carbon fiber/ ABS composite panel which can be obtained online... Thickness was aprox 3/8"... price was reasonable.. easy to work in cutting out the various holes (round or square/ rectangular). Reasonably rigid and light for use in light sport aircraft. Panel width was 24" by various lengths. I recently obtained this material, fabricated my instrument panel for my Ridge Runner 1.... very pleased with the professional looking results. Jay W. Sample #### autoreply ##### Well-Known Member I do get it that some are more comfortable working with composites. But if you have a waterjet and a sheet of aluminum, wouldn't you be 'done' when you get 33% of the way through the 1st step? To meet stiffness that alu would need to be rather thick and heavy and yes, that'd work. Thin alu would also work, but then you'd have to put in stiffeners etc. I only use the stainless sheet as a mold/cutting template for the composite however. The protruded holes (by 0.007") are exceedingly simple to cut and trim to exact size. And let's face it, a carbon instrument panel looks a lot better too right? #### wktaylor ##### Well-Known Member OK, guys... I have to ask. My last couple of posts to this thread disappeared. Why??? As far as I'm aware I was not reprimanded... well, sorta not. OH Well. #### Marc Zeitlin ##### Exalted Grand Poobah OK, guys... I have to ask. My last couple of posts to this thread disappeared. Why??? As far as I'm aware I was not reprimanded... well, sorta not. OH Well. As were a couple of my responses to your posts. It's one of the things that I really hate about fora, in comparison to email mailing lists - the moderators have the ability to delete the past. On VERY rare occasions (personal threats, multiple posts that are completely off topic, Spam), I can understand the desire to delete them rather than just threaten the poster with banishment. But in the case of merely marginal OT posts, or posts that may not be quite as constructive as the OP wanted (or even as constructive as the moderators wanted, much less the OP), it really chaps my a$$to have stuff I spent time writing disappear into the ether. If someone wants to ignore anything I write, the forum provides an "ignore" function that makes me disappear to THEM. If someone thinks I'm full of$hit, they're welcome to say so to me and convince me of it.

But having my stuff just disappear? Well, that seems overly manipulative and controlling, and in fact, in THIS case, I think that our exchange actually was useful in elucidating what the issues here were and why decisions get made the way they do in both design and fabrication of E-AB aircraft.

So it bothers me too .

#### wsimpso1

##### Super Moderator
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Moderator Mode On

OK guys we moderators do take this whole topic of maintaining thread topics and not losing posts more seriously than these last two posts imply. Let's start with the fact that I moved the separate topic to its own thread here:

I did this to avoid losing the notes and concern over that whole topic while addressing the original thread's continuity.

When moderators relocate or delete posts, we generally send a note to the authors of the move or deletion. I believe I did this when I moved these posts to their own thread. My apologies if I missed that step. Deleting posts are generally limited to removing posts that violate our code of conduct and to posts that repost those violations.

Moderator Mode Off

Billski

#### Marc Zeitlin

##### Exalted Grand Poobah
Let's start with the fact that I moved the separate topic to its own thread here:... When moderators relocate or delete posts, we generally send a note to the authors of the move or deletion. I believe I did this when I moved these posts to their own thread. My apologies if I missed that step.
Good enough - I don't remember seeing any notice of posts being moved, but if they're just somewhere else, that's perfectly acceptable. Thanks.

Of course, you could spend the rest of your life re-organizing off topic posts .

#### rv7charlie

##### Well-Known Member
Billsky,
Some forums allow the mod to leave a 'tail' or pointer where the relocated post originally was made, to point the poster (and the rest of the readers) to the new location.
Just a thought...

BJC