"Mr. Spock, have you accounted for the variable mass of whales and water in your time re-entry program?" - Kirk, Star Trek IV

 

The XT-14 on the way home. Shiny. Very XT-14

I should start off with the obligatory, “I love Pop Wilder.”

I do. But the man didn’t have much skill when it came to building/assembling/making stuff. I had to bite my tongue more than once while he was assembling something or other that he’d bought for Ma Wilder and was preparing to assemble, say, a pottery wheel. The problem was he was assembling it in such a fashion that it became a device only slightly less dangerous than a chainsaw in the hands of a crystal-meth-crazed rabid cat.

Speaking of cats, my theory is that Poe didn’t write the story “The Pit and the Pendulum” with a cat as the protagonist since the cat would have batted at the shiny blade as it went past. Just thinking . . .

Anyhow, I think that Pop Wilder fundamentally hated putting things together, since we didn’t carry all that much liability insurance, and he was concerned that my Pinewood Derby car might fragment into a thousand pointy wood shards moving at some multiple of the speed of sound as it went down the track. This combined with the round-trip distance of nearly 100 miles to the Pack meeting and the prevalent -40°F temperatures in January when I grew up were the reasons we never put together a Pinewood Derby car.

So, when I was working with The Boy, it was the first time that I’d been a part of Pinewood Derby.

I didn’t go onto the Intrawebs and buy a whole bunch of exotic tools to machine my wheels to tolerances of 1/1000 of an inch, or even lubricant made from the ear wax of elves. I did however, go to the Scout Shop and bought a book and scale for about $10 (American).

The first point is the car should be as close to the weight limit as possible. This is so that it is classified as an SUV and will thus be safer in the event that it crashes, or perhaps that Galileo was wrong and that heavier things actually fall faster than lighter things.

The Boy corrected me:

Father, in reality the “heavy” mass is so that more momentum (mass times velocity) builds up while the car is on the rampy part of the track and before it hits the straightaway. More momentum is good, since that kinetic energy can then be used to overcome the frictional forces at work in both air resistance, rolling frictional resistance of the tire on the track, and the frictional resistance of the wheel against the axle. Of these components, the frictional resistance of the wheel against the axle is likely most significant. Lubrication of this interface between components is critical.

Well, um, okay. See, and I thought friction was the result of your wife meeting your ex-girlfriend. Do I have a lot to learn.

On The Boy’s advice, we polished the axles.

The Boy and The Mrs. painted the mighty XT-14, covered it with shiny lacquer, and it was time to weigh it in. Before painting, the XT-14 had been just slightly underweight on my crappy scale. After painting it was dead on.

On the designated day, The Boy and I took the car in to turn it in

On the “test” scale, the weight was perfect (5 ounces).

On the weigh in scale, the weight was 5.1 ounces.

After shaving off a 2x4’s worth of wood, we finally checked in the car. Now, our major problem – how to get to sleep before race day?