The Matterhorn Bobsled Derby Car

Gamer Dads don’t only play video games with their family. They are also involved in other activities such as little league or soccer. In addition to coaching my kids’ sports teams, I am also the Cub Master for my oldest son’s Cub Scout pack. This month we had the annual pinewood derby. If you have never experienced one of these either as a child or an adult, you are missing out. 

For this race, cub scouts and their parents take a 7-½ inch block of wood and create a racing car out of it. In addition to the block, the kit comes with four nails (axles) and four plastic wheels. The finished cars are then raced down a wooden track approximately 35 feet in length which is elevated four feet high at one end. Gravity supplies all of the power as these cars accelerate down the track.

While the cub scouts are supposed to take an active role in creating the car, parents tend to get involved—some quite a bit more than others. As our son began planning out what he wanted to do for his car, my wife took the lead in design. She is much more creative than me. We wanted to do something different, so my son chose to make his car look like a Matterhorn bobsled from Disneyland. The two of them worked on cutting, shaping, sanding, and painting the body of the car and ended up with a good looking final product.

While they made the car look good, I concentrated on making it fast. Since gravity is the only source of power for the car, there are two main factors to increase the speed of one of these cars—increase weight and decrease friction. The weight is limited to a maximum of five ounces—so it is important to have the final race weight right at five ounces. Since the cars do not travel that fast, wind resistance is not that big of a factor. However, the friction with the wheels is where a race is won or lost.

For the race, you have to use the axles and wheels that came with the car kit. Graphite can be used for lubrication—but nothing else. You can’t add bearings, bushings or washers. After doing some research, I learned that it is important to make the wheels and axles as smooth as possible. I sanded off the molding imperfections on the surface of the wheels and also filed off the burrs on the axles before polishing them to a smooth shine. Finally as we were attaching the wheels to the car, we made sure that one of the front wheels was a bit higher than the rest so that the car ran on only three wheels, further reducing friction.

While the three of us had a good time building the car, the entire family enjoyed the race. As my son raced and I was the official starter, the rest of the family cheered on. My son was in the finals and in one race, had to go three times against another car since it was too close to call for the eyeballs of the judges. (Video tape reviewed at home showed that my son won the first two times). He ended up coming in 4^th place. It was a lot of fun. Some fathers really get into this race. The car that won cost the father (who is an engineer) about $300 in research and parts—but I am not bitter. We had a good time working together on the car and watching my son race.

Now that the derby is over for the year, we have some more time to get back to video games.