CRAZY wing construction idea

[teamfour]

I know my car isn't an FB, but y'all are the closest thing to my FB lite , so here goes.

I am thinking of building wings out of styrofoam-like material and then having them sprayed with truck bed-liner material. I remember an ad where Line-x sprayed a styrofoam cooler with material and then someone could stand on it. So the material is pretty strong but should be light weight in a thin coat. I don't have the bucks for a one-off carbon fiber wing, and don't want to hassle with aluminum, hence the foam idea.

The mounting points would be adhered to the foam prior to spraying. I would probably put two aluminum tubes through the foam to act as spars and provide mounting points for the aluminum end plates.

Am I nuts?

[Wright D]

Truck bed liner might be strong enough, but I don’t think that it will be stiff enough. You may end up with a wing that is just too flexible, and would bend under the aero loads.

The easiest way to make a wing is to start with the same foam core with an aluminum tube through the center, and then just do a wet layup of fiber glass wrapped around the core. Let the aluminum tube run a few inches longer on each side, so that the wing can rest on two saw horses after being covered in glass. If you place the wet glass and wing down on the bench you will leave a flat spot. Supporting the wing with the spar eliminates that problem. This is an awesome technique for one off profiles. For sure the wet layup will be just as smooth as the sprayed on liner. You can even use a fine weave on the glass, and wrap the whole thing in a plastic painters trap to get a smooth finish. If you wrap the wing in plastic, make sure that there are NO wrinkles. If you squeegee all the air bubbles and excess resin out you should end up with a pretty smooth and light weight wing that will only need minimal sanding before painting. I used to build FSAE wings, and model air plane wings this way, and after a bit of practice, the results are pretty awesome.

[teamfour]

Dustin, I knew you would come through for me. Having built a few glass cars, I can't believe I totally dismissed that medium. Duh! Sounds like a plan.

[Wright D]

If you use the white bead type of foam make sure you use epoxy resin. Any foam made of styrene (Styrofoam) will get dissolved by resins that have styrene in them (vinyl ester and polyester)

[teamfour]

So like West Systems would work. I used a lot of that when I finished my Cobra body. Easy to work with.

[Craig Henry]

Most of Burt Rutan’s wing designs utilized this method of construction. The foam is placed between two plywood ribs and then hotwired cut.


http://www.actechbooks.com/products/act431/

[teamfour]

Thanks Craig. I have spent the past hour researching hot wire foam cutters and techniques.

Now, where to find foam? Will the pink stuff at HD or Lowes work?

[Wright D]

The pink and blue foam that is sold at home improvement stores works well. It is a styrene based foam, so you will have to use epoxy, like the west system you mention.

The blue or pink foam will cut with a foam bow very well. I made my own foam bow using an old adjustable battery charger, a wood frame cut from ply wood, stainless steel safety wire, and a spring to hold tension on the cutting wire.

[Joefisherff]

Be careful which foam you buy as some put off toxic fumes when cut with a hot wire. Check out aircraftspruce.com to find out the appropriate foam to be asking for. They also carry the hot foam cutters.

[CSHAW]

Be careful which foam you buy as some put off toxic fumes when cut with a hot wire. Check out aircraftspruce.com to find out the appropriate foam to be asking for. They also carry the hot foam cutters.

LOL But so to the resins, solvents, hardeners, welding fumes, formaldehyde used in MDF and other assorted raw materials, VOC's from paint primers and particulates from sanding, and about everything else used to make a race car from. Just stating the obvious "wink" Just use what works, is easy to get and cost effective. If you ship a piece of foam from Georgia, make sure you get a freight quote. $20 per sheet of 2" pink foam from your local home improvement is a good thing.

[Joefisherff]

Before making flippant comments you might want to educate yourself on the Benzene, Styrene and hydrogen Cyanide that are given off. None of which you are normally exposed to, nor are as deadly, as most of the normal chemicals we deal with. Bottom line get the right foam, not the easiest to obtain, take the necessary precautions regarding masks and ventillation to preserve your brain cells.

[CSHAW]

Don't sweat it Joe, I'm just making light the fact that working around any of this stuff can be dangerous. I spend more time in a mask, hood, and protective gear than I do without and would love it if I did not have to but it is the nature of the beast. Those of us that have to pay the Workman's Compensation Insurance premiums, have to deal the the regulatory agencies, and have deep pocket lawyers lurking around propositioning employees to create a lawsuit, (Illinois at its finest), pay very close attention to the risks and do read the MSDS's. A simple fact is that if you wish to avoid exposure to anything that could harm you, then fabricating race cars with composites is not the best choice of hobbies. All of this stuff is full of nastiness. Warning composites fabricators to wear a safe breathing device is like warning a welder to wear eye protection. Your warnings are well founded, but just because you buy something from Aircraft Spruce, does not make it safe. Wright D recommended polystyrene foam for hot wire cutting, not polyurethane or PVC foam, and his recommendation is good and it works very well, and you do not have to buy it at Aircraft Spruce. Yes, you do have to wear protection and when you go to purchase the foam, go to the counter and request the MSDS and actually read it. Laugh Joe, my remark was meant as humor.

[CSHAW]

By the way, you can use a car battery charger, a cheep router speed control as an adjuster, and high nickel stainless wire for a great cheep cutting setup. You can also find nickel chrome wire for a reasonable price on the net and at your local appliance repair supply store, it is used as heating element wire. Warning: hot foam cutting is addictive and proper precautions should be taken to only cut what you need because use of the electrical power will cause global warming

[GRMPer]

Sounds like fun. Just pick an airfoil profile and try to match it? I would think that making a pair of 1/2 female templates (one top, one bottom) out of plywood would be the easiest way to check to see if you're cutting it right.

[helocat]

Lee – sounds like you have moved away from the truck bed liner already. One more voice to say away from it. Even in light coats it is quite heavy but most importantly it is flammable. We have had it catch on fire in our shop once, nasty smoke. Good luck with your wing!


Mark

[cparsons]

It's fairly easy to make a "one off" mold for composites. Draw the profile of the end onto some wood (2 or 3 times, be consistant with the spacing on the wood so they are the same dimensions on the exterior) cut the shape of the profile out and set aside. It's the other part you want. Join them together using 1 on each end and 1 in the middle by adding 1x4 (should be wide enoug) along the outside. Use the thinnest piece of laminate (ie. formica) you can find, cut to desired length, and glue it into the frame you just made, finish side up. Glue a piece on the ends also, to complete the "box" and you will have flat finished ends for the end plates also. Wax the laminate several times, then lay your composites into it. wait for it to kick, and pop it out. VIOLA!