Bodies for SPEED!!!

[Darin McGrew]

(front axle area = .25"x1.75"x.5") + (2 rails each = .25"x.25"x5") + (rear axle/weight-holding area = .25"x1.75"x1.5") = 1.5 cubic inches of wood,

lengthen and taper the front axle area, full thickness only at the axles.
reduce the rail width to 1/8".
reduce the rear axle/width holding area to 3/8" X 1/4" X width ... only center wood around axle ... void fore and aft.
and recompute.

Doesn't get down to 0.1 oz, but should be well below 1/2 oz.

Now I see another reason to have the cars' owners stage the cars for each race. As a pit crew worker, I'd be afraid of breaking a car like that.

[Stan Pope]

Now I see another reason to have the cars' owners stage the cars for each race. As a pit crew worker, I'd be afraid of breaking a car like that.

A little fear is a good thing!

Actually, in the past 16 or so years that I've been building and coaching, only two have been broken:

I pushed the envelope, taking the rail down to less than 1/16" X 3/16" (including paint) and had the front axle hole too close to the juncture between rail and front section. One side separated there during post race handling, possibly when I put it on display on its plaque.

My son was painting his creation and while hanging it on the basement ceiling water pipes dropped it to the basement floor. Cracked both sides! His rails were rounded, and diameters under 0.2". Breaks were clean, so we squished some epoxy between the breaks (after cleaning off the messed up paint and misc. basement floor workshop crud.) He went on to win the Webelos II races at district. Not quite enough weight on the front wheel, and the car came loose at times near the finish line, and that probably cost him the overall crown. Could have been wheel runout (hub off center by a thousandth or so)also.

Grandson had a bit of trouble staying on the line as he cut out the center of his car... a few cuts went into the rail portion. When the rasping and sanding were done, we poked some epoxy into the worst of the miscues and he went on to an undefeated season in his council!

Most of these cars get dumped into a plastic tub to take to PW Dog and Pony Shows to help stimulate youngster's imaginations. Although they are amazingly sturdy, I don't recommend throwing them or standing on them.

But, if fear will encourage organizers to keep the participants hands-on in racing, let there be more fear!

[ExtremePWD]

The first car my son made had a thin body rail (center) and it got dropped in all of the excitement on trials night and broke the front end. He had to make a new car in the 1 week left until the main event. Our current designs have a solid body that is less than 1/4" thick for most of the length. The risk of breakage is not worth missing the race. We have developed a method to use lead (without melting) that still allows us to place the CM at 7/8" or less in front of the rear axles (maximum distance back). If you can achieve your target CM location and can keep the profile low for aerodynamics then there is no need for risky thin sections. The use of higher density tungsten theoretically makes it easier to get the CM back on a solid body but the workability of lead more than offsets the density benefits if you are creative in using lead. Only if we wanted to run in the 1/2"-3/4" CM range would we start to hollow out the body in the front. However, this range of CM is too sensitive to track anomalies so you better be sure that it is a very smooth track if you want to run in this range.

[RACER X]

We had a car with a section that looked like it was going to be a bit vunerable to damage so we used fiberglass resin [no cloth] to strengthen it. Made it very strong and sealed the wood nicely. It also added very little weight. My son also got a nice little lesson in chemical reactions and learned about mixing.

[ExtremePWD]

When in doubt, beef it up. Sounds like a good proactive step you took to make the car stronger. I'm sure it would be a big disappoitment to any kid if his car broke at the last minute and prevented him from racing after investing a lot of time building his car. This also begs the reminder to store and transport the car in a safe container and spend a few minutes with the scouts about caution while handling their cars.