Waiex #142's Panel - A Dual Dynon Skyview System for a Sonex

[142YX]

Here is another update on the panel progress:

For the angled corner attach pieces that are normally 1/8" aluminum, i made another MDF tool to make these out of the green composite again. Here is the bracket stock under cure


I forgot to take some pictures of the tool construction, but you can see the tool in this photo; it is simply a flat plate with a 30 degree incline. At the interface, i made a radius with Bondo and a Popsicle stick. I used the same resin-wipe, wax, and PVA release process to finish the tool and prep for the layup. The angle stock was 12 ply, which came out pretty close to 1/8" thick. On the panel, i only used the green carbon stuff on the topmost layer with regular carbon underneath. On this angle stock, just for the heck of it i tried using the green carbon through out, thought it might make a cool edge effect on the side of the brackets. Worked out pretty cool, they definitely look neat.


Here is a detail of the edge look:


To stiffen up the whole panel, i cut a scrap of 1/8" thick x 1" wide by ~34" long carbon to bond to the back side of the lower edge, bridging the gap where the radio section is.


This adds tremendous stiffness to the panel


To bond the stiffener to the panel, i used West System resin with slow hardener, and thickened it with Cabosil into a paste. I gooped the paste on, wiped off as much of the squeeze-out as i could, and then quickly cleco'ed the whole assembly into place to cure. If it was going to distort or warp any, i wanted it to do so in a way compatible with the space where it will be installed later


I didn't know how good this approach was going to come out, so i decided to change my original idea of relying on this stiffener to take the fuel tank g-loading that the stock panel does. In stead, i ended up making a really beefy cross member out of 1/8" aluminum L stock that links the two longerons immediately aft of the fuel tank. This way i don't have to rely on how good my panel comes out to take that load. The airframe will be plenty strong even without any panel in place. In this photo, you can see the cross member back there behind the panel.

[142YX]

I took a "splash" of the aluminum radio tray that came with the SL-30. Using teflon tape as a release, I just wrapped the tray itself with wetted out fiberglass. I couldn't vacuum bag the tray as it would have collapsed, so i just held things in place with some paint stir sticks and some masking tape. I made this with 7 ply's of fiberglass (quasi-iso), which was too much. If had to do it again I would probably go 5 ply.


After cure, I trimmed the edges a bit and this is what i was left with.


The part that I made molded very well into the recessed channels on the side of the radio tray with the pressure from the paint stir sticks.. resulting in a very satisfying "snap" as the fiberglass part slides into position over the radio tray (although I am still going to attach the aluminum tray with a few screws)


Using a .010" pice of scrap that luckily provided just the right spacing for my radio to be centered in the hole that I had cut in the panel, I bonded the fiberglass tray into the panel structure with some more resin-cabosil paste


Now, here is where I screwed up. I was in a rush to get this done so that i could put my airplane on display for a fly-in that was at my home airport the next day. I had fully intended to strengthen this joint that is taking a big cantilever load from a heavy radio with a rib that would run up the back side of the panel between the two Dynon screens. I didn't have time to get this done before the event, but when I test fit the radio, it seamed strong enough to support the radio, and it probably was in a static, non-multiple G situation, but the resin had not fully cured. Foolishly, I convinced myself that it would be fine so I let it sit out in the hot sun all day like this, with the radio installed. The joint did not fail, but it did sag under the weight of the radio, and eventually fully cured with about a 5 degree slant to it. Kicking myself over this one, but it is not worth re-doing as it doesn't interfere with anything or degrade function, and it is barely noticeable. So I will just live with it :(


Now that the fly-in is over, time to make that rib that I should have done sooner. Couldn't find any scrap material that was up to the task, so I made a third tool to mold a nice rib out of:


Detail of the edge; it is just a flat plane with a 90 degree edge and a 1/4" radius (the smallest router bit that i had on hand, could have gone smaller).


And then I laid up and vacuum bagged this tool just as before. I used 5 ply's for this, again quasi-iso, despite it being primarily a shear path between the radio tray and the face of the panel. I did so because of its increased bearing strength (I plan on bolting some stuff ie, Dynon backup batteries, directly to it) and because I am also going to attach it to the top of the glare shield as well.


BTW, this is what I mean when I say quasi-iso (quasi-isotropic) (left) vs standard 0-90 ply direction (right)


Here is the trimmed rib, ready to be bonded on, again using a resin-cabosil paste


I used cleco's and some tape to hold it in place while it cures. If you use clecos to do something like this, coat them in wax first so that they will release easily and not become a permanent part of your project!


After the paste cured, I strengthened the joint further with some radius corner tapes. To make the radius paste, use resin and add cabosil and micro until it is the consistency of cake frosting. This will stay put and shape very easily. Here is a picture after i applied the slurry and before anything else:


Detail of the corner tapes:


And finally cover everything with peel-ply and set aside for a day to cure

[N111YX]

That's a panel that could only come from a Scaled employee... :lol: