Anyone good with composites?

[Acroeric]

Guys- I have a mold for a wingtip I would like to duplicate out of composite. Is there anyone on here that is really good with that type of thing. I'm trying to reduce the weight of some fiberglass clipwing wing tips.

Also- We started on my airstrip ysterday. We got about 100' of it roughed in. We had to take 2' off the top and move the dirt to a low area. It is really rewarding to finally see my little 900' airstrip in work. I wish we could work on it today but it is raining- so far I have built 3 new ribs for the project so it has not been a waste!
Eric

[Vasey fan]

Re: Anyone good with composites?

Composites? Friends don't let friends fly Tupperware

But seriously, have you tried the local racing guys? (cars or boats)

Congrats on the strip progress, I'm not going to say how long it's been since I worked on my T.

[VictorBravo]

Re: Anyone good with composites?

I think you got a good piece of advice there about the race guys. North Carolina is NASCAR territory and I'm sure there are plenty of glass guys up there who can help you.

My guess is that you could find someone who has done composite work and who has some bidirectional carbon fiber fabric scrap lying around. Have him put two players of medium weight carbon cloth in the mold and put a layer of "peel ply" (otherwise known as Dacron or polyester aircraft fabric) in after the carbon, in the areas where you arte putting in bulkheads.

When you are ready to put in the bulkheads, rip off the peel ply (it doesn't stick to Epoxy and when you rip it off it leaves a fresh rough surface to glue to), and glue in some rigid foam bulkheads to stiffen the surface. That way, you can take advantage of the light weight of the carbon, and not have oil canning problems. If you made it STIFF enough with carbon only, you'd have to use twice as much material (weight and money).

My recommendation is Divinycell PVC foam, tan color (medium density) for the bulkheads, glued in with whatever resin they use for laminating, mixed with "cotton flock" to applesauce consistency. Again my guess is that two of these foam bulkheads, perhaps one at 25% chord and one at 60% chord, and two layers of 6 ounce carbon cloth in the mold would suffice for an experimental acro plane, giving you a very light and stiff structure.

If you want to get fancy, have him put in a layer or two of extra "tape" (narrow strips) on the edge where you will attach the screws to the end rib.

If you want to get fancy-shmancy, you can have the guy use Kevlar instead of carbon, which will make it tougher and last longer, but Kevlar is hard to work with and he will have to put a lot more effort into the edge where it is cut.

My guess is the NASCAR folks have lots of experience with this, all you have to do is fine one that is not too busy on high-dollar projects for a sponsored car.

[1938BF50]

Re: Anyone good with composites?

Eric,

Sounds like Bill is dead-on. Give me dims and I will try and beg some bias-ply from the carbon dept here at Trek. If I can get oversize, do you have a "pizza wheel and backer" to cut scraps to size?

[Acroeric]

Re: Anyone good with composites?

Guys- Thanks for the suggestions. I work with some of the NASCAR guys so will follow up next time I am at their hanger. Basically I just want to take the 11 pound Swick wingtips and make them out of a lighter material- these weigh a ton! I plan to make a mold if anyone else needs some.

TREK? I ride a 2300 road bike as much as possible but also have a Specialized MTN Bike. Love the TREK- great ride.

I will get the dimensions asap. Pretty much the length of a rib and about 8 inches wide.