My son is a Wolf; this is our third year of competing. Last year, we played with using plastic sheets to decorate the car in novel ways. Our Ghost pirate ship was awesome and the fastest and tallest (and only) boat in the pack. It did well until hobbled on race day by a registration sticker. Our Toothless, the Midnight Fury Dragon was just for show, not for racing, as its wings fluttered badly in any wind and there was no room in the tail to hide any weights.
This year, kiddo wanted to go for speed rather than looks. But when we cast about for a decorative theme, the obvious answer for him this year was Angry Birds. I sketched how we could put little bird and pig faces on the top of a fast slab car. Faces that few would see. Or we could instead put an entire scene on a large upright sheet of plastic, much like we did for the ghost pirate ship sails. We decided to risk some speed to go for the big look again.
The car's wood base is a simple rectangular slab, 5/16" thick. (I meant it to be thicker, but sanding out our rough coping saw marks took away than I expected.) Primary weighting is by 6 half-ounce tungsten slabs, arranged around the rear to minimize air drag cross section and also get the c.o.m. as far back as I could:
Final weight on the front axle was 21 grams, and 121 grams on the rear axle, putting the com at 0.6" in front of the rear axle. There was absolutely no fishtailing with this com position. It is possible that the sail helps stabilize the car's tracking. (As required in our pack, this was with a standard wheelbase, all four wheels rolling, & no camber.)
The car body's small cross section area reduced total air drag to less than our pack's wedge cars:
On average, Angry Birds was 0.01 second faster per run than the next-fastest car.
I encourage others to use thin plastic sheets for car decorations. It opens up a huge space of possible intriguing designs.
