Landing light cover

[colospace]

I'm installing Hoehner wingtips and I've made my own wingtip light cutout. I'm using 1/8" Acrylic sheet. 5 minutes in an oven at 200F and you can do anything with it. It droops like jelly and you can drape it to whatever contour you want.

I made several attempts at using acrylic, even baking at a lower temperature to bake out any moisture, before ramping to forming temperature. Always ended up with small bubbles in the plastic. Not sure what magic I was missing, but finally just went with Lexan which went well. What was the secret for you David?

[David47]

I made several attempts at using acrylic, even baking at a lower temperature to bake out any moisture, before ramping to forming temperature. Always ended up with small bubbles in the plastic. Not sure what magic I was missing, but finally just went with Lexan which went well. What was the secret for you David?

I have no idea what secret herb and spice I used. But no bubbles. I simply bought the sheet from the local hardware and it worked out. Sounds like maybe I got some out gassing without knowing it ... that's all I can think of. I'm about to make some spares so I'll pay more attention to my process and maybe check for bubbles as the temp ramps up ... but my finished product was fine.

[David47]

Gary, I'm trying to upload photos of my lens formed in acrylic but I'm having trouble. But I checked the first stage form (I do several stages to get the exact fit) and no bubbles evident.

The only thing I can think of in your case may be the chemical formulation used in the acrylic you bought. I'm no industrial chemist, but it may be that there are slight differences in the chemistry that may lead to bubble formation. More knowledgeable people may like to comment.

[colospace]

The research that I did at the time, spoke of acrylic absorbing moisture from the atmosphere (which I really didn't expect to be a factor in our dry climate in Denver). I don't recall the temperatures used/called for in the literature, but I had ultimately done a long bake out prior to ramping the temperature. Option 2 using Lexan was easy.

[Esser]

I just ordered 2 covers from Kitfox. $15. That’s cheaper than you can buy the sheet for.

[David47]

The research that I did at the time, spoke of acrylic absorbing moisture from the atmosphere (which I really didn't expect to be a factor in our dry climate in Denver). I don't recall the temperatures used/called for in the literature, but I had ultimately done a long bake out prior to ramping the temperature. Option 2 using Lexan was easy.

Yeah, thats really strange. I went back and checked (a) that I was using Acrylic .. tick, then (b) checked my facts about 200F for five minutes... tick. Then just to make sure, I did 4 more temp cycles in the kitchen oven after the first .. my partner in life didn't appreciate that because the odour wasn't great and she has a sense of smell like a bloodhound .... and no bubbles in any of them. Also checked the internet re heat forming acrylic ... heaps of youtube videos with similar results. So I know it's too late, but maybe look for another supplier of Acrylic if you plan any other transparencies. BTW, there was a really great seminar at Oshkosh this year about Acrylic, Polycarbonate etc ... focused on care and attention. Learned a lot, but nothing about forming.

[colospace]

Hopefully I'm about done fabricating stuff. Need to complete the leading edge cuffs when I get back home, and my seat cushions. After that it should be a group/tech counselor inspection and start filling with fluids. And the bazillion other final things to be done.

[runwayrex]

Any suggestions on how to get a nice fit of the lens?
I’m having difficulties because of the recessed fit on the wingtip and the butt fit against the spar. I’m using the supplied Lexan lenses from Kitfox.

[David47]

Hopefully I'm about done fabricating stuff. Need to complete the leading edge cuffs when I get back home, and my seat cushions. After that it should be a group/tech counselor inspection and start filling with fluids. And the bazillion other final things to be done.

Well it sounds like you’re about to push the go button. I wish you well with the C of A and hope you’ll post some pics of the project.

[efwd]

here is what i did. first you have to get the lens right side up. the leading edge profile has to be mated with the lexan. After my lens was installed I had a little gap between the lens and the leading edge of the wing. It was very small but I also didn't like seeing the open end of the spar when looking into the lens. I used a balsa wood plug to close off the end of the spar and used poly fill to dress it up flat. Added a tiny bit more of the poly fill to close that small gap, sanded and painted it. now the spar side resembles the wing tip surface next to the light. Im no body shop guy so I learned that poly fill looks smooth and finished until paint goes on. my point is, you can tell that its body filler that I used and I didn't get it absolutely smooth as is the fiberglass on the opposite side of the light.