Remaking left landing light cover - Part 1

TLDR

• Created a new landing light doubler for the left wing
• Tried to make a new landing light cover, but failed. Will try again.

Details

As I wrote on the previous blog entry, the landing light cover did not fit at all. I tried to force it into place, but it snapped and broke.

Cracked across horizontally

I ordered a new part from Sling, but without knowing their ETA I really want to get this step completed so I can full close the wing part of the build process.

So I decided to make my own cover. And while I am there, I also decided to make a new doubler because the old one was shit too.

Molding

The first step is to create a mold. I followed Another builder’s experience shared on the Sling build facebook ground.

It’s larger and longer than what’s actually needed, and probably doesn’t precisely fit on the wing. But the cover is made from plastic it’s very flexible, so I am not worried about precise match.

To get the mold, I cut a foam block and pushed it onto the wing. Then I traced the foam to cut the shape of leading edge.

Press the foam to get the shape

Then I transfered the foam shape to 2 pieces of wood boards and got started on cutting. These are the 2 sides of the jig.

Once the 2 ends are done, I cut some 2x4 as the jig’s center beam. The total length was 15 inches just to give plenty of extra space for later.

Framing

Once the ends and center and screwed together, I sanded the curved leading edge parts, and put a piece of aluminum on top.

Here is the completed product:

Mold for the cover

Template for doubler

Next I needed to manufacture a doubler.

I put a piece of paper on the wing to fully cover the light area. I pressed my hand on the paper around the landing light area to get the shape.

Then, I took the paper off and traced the general area with pencil. I added 1/2 inch around the area and traced another big circle. The 1/2 inch ring will be the actual shape of my doubler.

The paper was too slow, I did not want to use it as a permanent template when cutting aluminum. So I laid the paper on a piece of art acrylic board, and cut the board to shape. The thickness and rigidity of the acrylic will provide a lot more guidance when I cut aluminum.

Template laid on top of aluminum

Outer shape cut for the doubler

Inner shape cut as well

The new doubler is ugly, but it works. I get to drill the holes exactly where I need them.

Drilling

I attached the doubler with cleco clamps on the wing, then drilled all the holes to the size for M3 rivnuts. Then I installed the rivnuts with Loctite 277. I did a test fit, some rivnuts are little tight but they all fit. I think I will slightly enlarge a few holes on the skin to make them fit better during final assembly.

Doubler completed

Polycarbonate cover

I bought a 12x12 Polycarbonate sheet on amazon as the new cover. The thickness is 1/16. As it turns out it’s too thick. It’s too difficult to bend.

So anyway, I cut the sheet to the right size, and forced it onto my mold.

The material is so stiff, I had to use 3 safety wires to hold it in place.

I put the whole thing in oven at 330 F degrees, hoping to reach 170 C to get it to bend. But apparently 330 is too hot. 5 minutes later when I looked at the over the material is all warped lol, and the other place is uneven. Basically the bent sheet is unusable.

Warped around safety wire

So I bought a few more thinner sheets, 0.04 inches this time. It should arrive soon. I think I will change my strategy with the new sheet. I will bend first, then cut. I feel like this will allow less precise control on the cutting.