Bobcat1506

I have built a few SPADs for both SCC and Class C combat and was wondering if anyone has any suggestions on how to improve a Combat SPAD wing’s durability?

I thought of filling the wing with expanding foam but I am not sure how that would affect the airfoil and weight. Has anyone else tried this?

Is it legal to adhere some protection to the LE? If so, what have you tried and what has worked well?

mclina

What kind of damage have you experienced, that you are trying to prevent? I have seen SPAD combat planes drilled into the ground at full throttle, and the wings have looked good as new.

I think that filling the wing with foam will make it fly more like a brick than they already do.

I like the idea of a music wire spar, like in the GNAT and SPA3D plans, it stiffens up the wing pretty well. Maybe you could so something similar on the leading edge.

rrh

It's when our bricks go wing to wing in mid-air collisions with the foamy wings that our coroplast gets damaged.

The expanding foam doesn't do much and is too difficult to get a uniform load in there. There are some guys who will form a LE from foam and wrap the coro over it and they claim it to be pretty durable. I have not tried this yet but I have tried FG reinforced tape on the inside, outside and holding 1/8" FG rods in the LE but they all take a beating in a wing to wing hit plus add a lot of weight. Currently I plan to build light weight throw away wings and take many of them with me to a contest.

OzMo

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A wire in the LE is too stiff, try a light piece of braided cord and a SMALL AMOUNT of poly glue. Just enough poly glue to anchor the cord but not enough to make it a rod. This could help a lot in preventing the tearing coro has experienced. Its a cheap enough experiment any way. The thought is to spread the impact force as the soft foam LEs do. hmmm Even in 2MM coro small nylon string could be employed in as many as four flutes at the wings LE area?? just thinkin' out load here I guess.

rrh

you are finding a lot of uses for that poly glued sash cord, good thinking [8D] I'll give that a try. Has to be lighter than tape and FG rods.

Bobcat1506

Thanks for all the suggestions. I have a few questions:

What is poly glue? Epoxy?
Is music wire similar to a coat hangar?
By braided cord do you mean nylon or steel?

OzMo

My Feedback: (3)

I'm a tight wad I built a combat wing with a light nylon rope LE. It was tough as nails. This is kinda the same construction philosophy. Can you imagine how tough 2 mill with good old nylon cord in the flutes would be?

The Internet Killer

Poly glue- polyuerathane (spelling) glue, gorilla glue,elmers ultimate glue and others.

Music wire has a higher tensile strength (not quite spring steel) a coat hanger would be considered soft in comparision.

I think the braided cord they are talking about is a braided polyester or nylon, the type used for window blinds.

Alex Treneff

Not sure if it's exactly what you're looking for, but US Army "550 Cord" (parachute cord) might be of use. It's named for it's tinsile strength. Pull the outer wrapping off and there are 7 inner strands that are strong.

http://en.wikipedia.org/wiki/550_Cord - on the right there's a picture you can expand.

http://www.rangerjoes.com/550-parami...00-p-2419.html - Rangerjoe's is a very reputable store.

OzMo

My Feedback: (3)

I think the chute cord would be 1/4 dia and a little large. The strands would work but would be kind hard to manage. but that is the idea...strong tensile but flexable. I think the chute cord would make a great LE before tape with just a smidge of contact cement to hold it.