Does anyone know where you can buy composite live hing material. I have used Spectra clothe in the past but it seems to be tough to find.
Any help would be appreciated

Thanks
Bill

I guess it depends on what you're after. Nylon peel-ply and Kevlar also work well.

-David

On that topic - Nylon Peel Ply - I seem to recall that there's a "fabric store equivalent". What is that equivalent?

Some folks use plain old rip-stop nylon.

I use 3oz Kevlar from Aerospace Composite Products. Peel ply is not suppose to stick to your fiberglass part, it soaks up all of the extra epoxy and you pull it off and throw it away. That would be a bad choice for hinge material.

I like kevlar because
- its a very tough material as you are scoring through to it. Sometimes, (depending on the actual application), as you cut through the outer wing skin material to contact the cloth hinge material, you can accidentally sliced through 'other' cloths even with TLC. Once its cut, it is no longer a hinge & kind of hard to repair. You can have the same situation with kevlar if not careful, but it is actually quite forgiving that way because teh fibers are so tough. Once scored, give the flying surface a crack to relieve itself of the epoxy & it has become a nice, slop free hinge
- its available in a few useful weights. I personally favour 2.2 oz
- depending on the source, it is avaliable in tape form too which can save you a bit of time cutting long ribbons. Although technically it should be layed on the hinge-line at a bias so you have more 'crossing' fibers, Ive layed it at a shallow angle & never had any issues. Once upon a time I heard Dacron ?sp? was sold in tape form through boat shops. Might be a good option too.
- in the permanent non-moving hinge, ie the cloth material fore & aft of the hinge line, kevlar then serves as a good structural material
- although I havent personally experienced it, some of the nylons & peel plys have been known to loosen up over time. This could be related to how it was bagged, any kind of release coating on it, or high deflection surfaces like flaps.

The epoxy makes effectively thousands of little rivets through the hinge material. I'd love to see you pull one apart without destroying the rest of the structure first. I can show you pictures of exploded wings (from flutter and collisions with terra-firma) where the peel-ply hinges are still intact. But, whatever floats your boat.

David's right. I used to worry about this because the tape material I was sold as 'peel ply' was in fact was re-packaged 'something else'. It had a greasy feel to me almost like teflon coating, epoxy seemed to come off easy so I chickened out. I never did find out what it was. I have since pulled enough legitimate treated peel ply off of bagged sections & takes some effort. Sometime I worry about pulling the layup off a well released mold. So I dont worry about this anymore, peel ply is probably fine, I just prefer the toughness of kevlar. I think any problems are more related to insufficient epoxy application, or epoxy which has wicked into the balsa skin & starved the 'riveting' process or meat hands have delaminated the joint during the flexing step.

2.2 oz kevlar.

Just don't try and sand it after the epoxy is dry.

Flag material sold in many colors at Joans Fabrics