Derby Talk

We just inspect the wheels visually. Anything that looks modified is rejected, and we hand them a new set of wheels to replace the modified ones. (Each box of 10 kits comes with spare set of wheels and axles.) There isn't much need to modify CSB's current wheels. They come with a narrow ridge (about...

My group seems set on limiting lubricants to "dry graphite or 'the white stuff' that BSA sells". I've already sounded off against this rule, but assuming you're stuck with it, here are some comments on the inspection techniques you've considered. 1. Affidavit by Cub Scout and Assistant. I...

That rule would seems easy to skirt and hard to enforce, so why have it? RandyL, this gets back to the fact that a scout (and his parents) should be trustworthy. My college honor code had two key parts: the students were required not to cheat, and the instructors were required not to create situati...

Do you use this silicon lube in combination with Graphite? No. Don't mix dry lubricants with wet lubricants. You usually end up with a sticky sludge that is worse than nothing. If you're lucky, then it's better than nothing, but worse than either lubricant used separately. Does it violate the rule ...

The promised surprise is this: We don't need to know where the CM is to reach this conclusion. It doesn't matter! We just need to know that the car rested quietly on the three wheels and that the cf in each wheel is the same. Aha! :-) And now that I've seen the math, the intuition follows. In the p...

Even without software and timer issues, with concerns over fairness, generally you'd want each racer to race in each lane, but is 12 lanes just too many? We give each car 8 races (2 in each of 4 lanes), and that seems about right. With a 12-lane track, we could theoretically give each car 50% more ...

However, this type of damping can still be considered to use "springs", so wouldn't it be illegal in many of your races? It would be in ours. How easy would it be to convince your judges that these aren't springs? Our rules don't prohibit springs per se. They specify: Except for adhesives...

Starting with straight line motion, compute the braking moments about the center of mass. Be surprised! Assuming that (1) the force of friction on each wheel is equal: f (2) the force of friction is in a straight line with the direction of travel (3) the CG is located distance d from the 2-wheel si...

What do people think about weights? I think one of the most important things to consider is the ability to adjust the weight easily at registration. I've seen too many cars ruined by the rough handling required to remove weight at the last minute. And extra weight added at the last minute to bring ...

How does your group conduct the judging for the design awards? The last few years, we've had registration on Wednesday night and the derby on Saturday night. So we have almost 72 hours to arrange for impartial adult judges to view the cars and assign awards. We have the panel of judges come in toget...

There are a variety of race scheduling methods in use out there. Which method do you use? We use custom software (one of these days we'll "productize" it and put it on the web, really...) that implements the "chaotic rotation" method described at the end of my Race Methods web p...

The axles may be like the Awana axles where they are machined pins and not nails. That sounds like the CSB axles, too. The wheels in the CSB kits used to be like the BSA kits, with a flat tread. Around 1990, the CSB kits switched to wheels that have a tread with a rounded cross-section, with a narr...

gpraceman wrote:Has anyone tried an award for the slowest car?

I like that idea. For speed, you could have 1st place fastest and 1st place slowest. For design, you could have 1st place automobile and 1st place unusual. There's a certain symmetry there...

It sounds like your regional derby was quite a bit bigger than ours. Would judges be affected by knowing which boy goes with some of the cars? If I could convince myself that this is a non-issue, then I think that I could sell the rest of the race committee to include race entries in the design judg...

There were plenty of trophies to go around, and no one cared whether anyone won two trophies. Unfortunately, not everyone has the budget for that, so they limit the number of trophies that a racer can win to try to spread things around more. However, paper is cheap, so why not give out a lot of cer...