Forming Plexiglas LE Landing Light Lens

[Mark Meredith]

Hi All,
I want to add a landing light to my aluminum wing leading edge. What's the best way to do it? I've thought about making a female mold (using fiberglass) over the LE to get the shape before cutting the opening.

Would I then need to make a male mold from the female? It would obviously need to be reduced in size by the thickness of the plexiglas.

Then I need to heat the plexi. Is it necessary to make a vacuum box, or can it just be heated and laid over the mold? What thickness plexi works best? How hot does it need to be for forming?

Lots of questions, but I'm thinking lots of people have done this before. I searched for a past discussion or YouTube video but struck out.

Tentatively planning to use the Flyleds 4 light landing/taxi kit.
Thanks!

Mark
Super Chipmunk N7DW

[Kyle Boatright]

Here's a thread from Vans Airforce:

https://www.ajc.com/news/puppies-roaming-the-georgia-aquarium/N23rrIBAT6Dt2qeIootd4L/

Sounds like you need a male mold and an oven.

[ahramin]

I made a male mold from wood and coated it with bondo and sanded it for smoothness, then heated an oversized thick plexiglass peice with a heat gun and pulled it into place wearing work gloves. Once it cooled I then cut it down to size. If I remember correctly it worked perfectly on the first try and was quite easy. Probably would have been easier and better with a thinner peice.

[ahramin]

Here's a thread from Vans Airforce:

https://www.ajc.com/news/puppies-roaming-the-georgia-aquarium/N23rrIBAT6Dt2qeIootd4L/

Sounds like you need a male mold and an oven.

Puppies?

[Mark Meredith]

Thanks Kyle! It looks like you posted the wrong link though. ��
I'll check VAF.

[Kyle Boatright]

Let me try the link again. No puppies this time, though I did enjoy the puppy video...

http://www.vansairforce.com/community/archive/index.php?t-74560.html

[Tralika]

You might try Lexan (polycarbonate). The thin stuff, .030" , is very flexible and easier to cut and drill than plex. No molds, no oven needed. You can buy it locally or order it from companies like eplastics.com

[Mark Meredith]

Kyle, I found the VAF thread, thanks. One poster said there's a section in Tony Bengelis' book about it. I may have it somewhere so will hunt.

[Mark Meredith]

Tralika,
So you just hand bend and screw it down? I may try that too.

[Mark Meredith]

Some of the discussion on VAF was about cutting a flange so the lens can fit flush, apparently inserted from behind. How is then lens then attached to the LE?

I had figured I would just make an aluminum frame, with a spacer so the 1/8 lens will fit flush with the .032 skin. Flush rivet it around the circumference of the LE cutout. Nutplates behind the frame. Then screw down the lens to the frame. Not an especially clean result though...

[Mike M]

I've successfully shaped acrylic as ahramin did, heat gun and heavy gloves. Didn't make a male mold just wrapped the floppy warm plastic around the underlying structure for shape. For a slow airplane one could just cold bend thin lexan (as sold in squares at Home Depot or Lowes etc) and screw it down over the hole. For a more elegant look on a faster plane, thicker acrylic. Mark's approach works well. Make a doubler to install inside, nut plates in the doubler, screw the heat shaped lens into the hole with spacers as needed to make it fit flush.

[Frank Giger]

Some of the discussion on VAF was about cutting a flange so the lens can fit flush, apparently inserted from behind. How is then lens then attached to the LE?

I had figured I would just make an aluminum frame, with a spacer so the 1/8 lens will fit flush with the .032 skin. Flush rivet it around the circumference of the LE cutout. Nutplates behind the frame. Then screw down the lens to the frame. Not an especially clean result though...

You don't have to attach the lens to the leading edge, as you sussed out, you make a frame for it with nut plates.

Here's how they did it for Cubs and other Pipers - make a false nose rib, and attach it to the spar the length of the light fixture away from a true rib. Rivet a half inch wide strip along both (.020 works great), and then tag another across top and bottom. You can cheat some strength in there by placing K1000 nut plates in the corners where each ear is on a different part, too. Also, cut two pieces of aluminum sheet that match the the airfoil of the nose rib and, after painting black, rivet to the sides of the ribs to keep the light out of the wings and going forward.

The real stunt is making the measurements to cut out the light fixture hole in the leading edge material. One wants to be shy to the fixture, as it's always easier to cut more off of a hole.

(I had to do this at work last month)

[Mark Meredith]

Mike, Frank,
Thanks much! I may quarantine myself in my hangar and get this done.