Before our foray into the world of Pinewood Derby Engineering, I hadn't given any thought to what made a car fast. Obviously, friction is bad. Anything that reduces friction makes the car go faster. What surprised me were the number of speed-em-up strategies that could be applied to a simple creation made from a block of pine, four wire nails, and plastic wheels. Here are a few:
- Sanding the wheel axles (wire brads) to remove tiny burrs that catch on the tires and increase friction.
- Applying powdered graphite to the space between axle and tire.
- Inserting axles at 90 degree angle to car body, to ensure straight tracking. Tracking must be tested to make sure that it followed a straight line, to prevent rubbing against the side of the track, which produces friction, which slows down the car. Adjust axles as needed.
- Angling one front wheel slightly upward so that it doesn't touch the track. Three wheels in contact with the track produce less friction than four wheels. (I personally am not convinced of this, since the same amount of weight will be distributed among three wheels, thus increasing friction on each wheel, thus net friction will be unchanged. However, since I was not consulted for my expert opinion, I kept my mouth shut).
- Weight distribution is also important. The farther back on the car the weight is placed, the faster it will go. I could explain why this is so, but it would require diagrams and several paragraphs, and since it is too early in the morning for that much effort, you'll just have to take my word for it. If you desire more details, please email my Pinewood Derby Engineer husband at firstname.lastname@example.org.
Nathan's first derby car (left), painted black with flames on the hood, sported vaulted nuts to provide the needed weight. It took second place in the pack -- not bad for the youngest Cub Scout in the pack! Nathan was proud, dad was pleased, and the car and trophy were displayed proudly on his dresser for many months.
2006 produced a red car of similar shape, with coiled lead fishing weights attached in front of a flared spoiler. This car also took second place overall in the pack, and fastest car in the Bear Den.
For 2007, Tom and Nathan decided to go a new direction with the car design in one last effort to produce a champion car. As mentioned above, weight distribution is very important. In order to put maximum weight at the back of the car, the pine block was cut very thin. A drill press was used to create 90 degree holes for the axles. The flat shape inspired the skateboard motif, and yes, that is C3PO hanging ten with the help of a little hot glue. A stack of weights was added to bring the creation up to the allotted 5 ounces, and wallah! -- a champion was born.
Kinda gnarly looking, isn't it? This car finally earned Nathan the title Pinewood Derby Champion... at least is would have, except that for some reason, this year, the Cubmaster decided to award prizes within dens only, rather than an overall champion. So while Nathan was officially only the Webelos champion, his car beat the Wolf and Bear champions, so I'm claiming Pack Champion as well. And nobody can stop me. So there.
Here is the proud boy holding his winning droid skateboard.