Over the past couple of days, I put together a new wing idea for my race car. I got the cores for some wings I plan to vacuum bag with carbon fiber. But my thinking was that I'd also try this potentially-lighter-weight idea.
This one is made of a stronger foam than the EPS (beer cooler foam) I used last time. It's a material used for surf boards called Spyder Foam.
I started out by tracing the airfoil shape on a piece of paper, and then drawing in the shape of my brackets.
Then I cut the shapes out and used some spray adhesive to stick them to a piece of plywood. In retrospect, I should have used at least 1/2" plywood. But I'll know that next time.
I sprayed primer over the adhered cut-outs and the wood.
So when I peeled off the paper, I had a line on the wood that I could follow with a jigsaw.
Here are the pieces cut out:
Then I cut out the same shapes in aluminum, but did a quick cut that left a lot of extra material around the outlines. The idea is to stick the wood buck to the aluminum with double sided tape and use a router to trim the aluminum to the exact shape of the buck.
I could have taken more care with the shapes, but using the buck allows me to make pretty-close-to-identical parts.
Here are the end pieces and the mounting brackets.
This is a lot nicer than the results I got on the previous wing, where I didn't have the right blade for the jigsaw.
Then I made L-shaped pieces to support the brackets, and a flat sheet to allow a large adhesive surface between the bracket and the wing. I used 3M Scotch-Weld adhesive.
I adhered captive threaded fittings in the end pieces, and attached the end pieces to both the wing and the aluminum tubing I'm running inside the foam.
I'd made a new (and lighter) set of supports for this wing. I used a jack to get the car perfectly level so I could make sure they're mounted symmetrically.
Here's the wing being test fitted. It's mounted slightly lower than the previous versions.
The plan was to skin the foam with Ultracote, a German heat-triggered plastic covering used by RC aircraft guys. But I knew I wanted to paint the bare aluminum. First, I checked to see if this foam would be vulnerable to the acetone in spray paint (like the EPS foam was). I dripped some on the scrap piece of Spyder foam.
Answer: it
does dissolve. That picture is of the scrap piece that was under the scrap piece I dripped acetone on.
So I masked it off before I spray painted the metal.
I hadn't ever worked with Ultracote, so I did a test piece on the scrap foam.
The only downside is that it has a glossy finish, which shows every irregularity in the surface:
It looks better from this angle:
The nice thing about the Ultracote is that it's light. My all-aluminum wing was 4 lb 14 oz. This is pretty light, considering it supports about 400# of force.
The second wing was EPS foam skinned with aluminum. It was slightly lighter: 4 lb 12 oz.
This new one made a big leap forward, in terms of 'wing anorexia.'
That's 3 lb 3-1/2 oz.
Here's the wing installed on the car, viewed from below.
For the top, I added a piece of black contact paper, which has a matte finish and looks a little better.
The iron I was using to shrink/adhere the Ultracote had a problem where the dial kept creeping up, which led to some inadvertent melting of the foam. You can see it if you get up close. It shouldn't affect the functionality, though.
And for the sake of perspective, here's a 3-1/2-year-old in front of the wing.
In hindsight, I would do a few things differently. I think my quest for lightness might have made me make the bracket too light. It might need some reinforcement in back to avoid bending. I also was learning as I went with the Ultracote, which left some cosmetic problems.
But I'm going to test the new wing this Wednesday. I think it's going to work pretty well.
Calling an early car (ESPECIALLY a '72 of all years) a 964??!!'
