Hello all. Originally for White Lightning I'd planned on creating a reversible (IE symmetrical from front-to-back-of-the-car) template and using fiberglass to create rear wheel skirts. After doing some research into the cost of this option, as well as the hassle of dealing with glass fibers, I decided to go a different route.
Fiberglass is certainly something I'd like to use in the future for other projects, but for now I'm going with ABS plastic sheets. I ordered two sheets of 24" x 36" in white ABS. The plan now is to create a template with cardboard that I can trace twice, and use a heat gun to create bends in the plastic to mold it into shape for each side of the car. I can also secure ribs and other supports to the back side for stiffness.
After shaping I plan on painting the ABS to match the vehicle, to provide some defense against UV damage and to blend it a little better.
So here is my Cardboard Assisted Design Mk 1.
First up, using a thumb tack, some string and a pen, I traced out a rough half-circle the size of the rear wheel well. I knew this would not be exact (and indeed it wasn't) due to the curvature of the rear of the car, but I knew it'd at least get me in the ballpark.
I taped a long piece of styrofoam to the back side of the support to provide a natural spacer against the tire, so that no matter what shape I came up with, it would give the tire a wide berth and (hopefully) prevent rubbing, even when the suspension is moving.
Here's a side view of the completed skirt template. You can see the strip of styrofoam on the left side, which has been removed now that mocking up is done. I have to say, I really like the way this makes the back end of the car look. Makes it look futuristic and smooth. It'll look way better when it's white and not covered in random pen marks and blue painter's tape.
Here's a front view of the skirt. I will even out the skirt edge with the mud flap on cardboard template Mk 2. It will smoothly transition and be level. Despite this unevenness, it still looks way more aerodynamically sound than the old, open well.
Finally, here's a picture of the egregious trailing edge angle that results from meeting the rear mud flap. I know for a fact this will not result in attached flow at the back end because the angle is much to severe, but there's not really too much I can do about it. Sure, I could make extensions that go farther up the back of the car (and I might, someday), but for now I'm going to leave it as-is. This transition is surely 'cleaner' than the solid metal lip of the wheel well scooping air into the hollow cavity. Unfortunately I think this is the best I can do with the trailing edge for now.
Anyway that's Mk 1. The next version will be cut from a single piece of cardboard and carefully shaped with an eye for keeping as much of the sheet unbent as possible. Let me know your thoughts, and I'll see you next time.