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## A former NASA engineer explains how you can use science to build a fast Pinewood Derby car.

For seven years, I worked at NASA on the Mars Curiosity rover. It is just like a Pinewood Derby car, except it has six wheels, it’s nuclear powered and it shoots lasers.

My Cub Scout son and I decided we would take the science principles I used while building stuff at NASA and apply them to making his Pinewood Derby car.

Take a look at some of those science principles in this video and check out my list of the most important steps for making fastest Pinewood Derby car possible.

## Seven Steps for Making the Fastest Pinewood Derby Car

1. Max out your Pinewood Derby car’s weight at 5 ounces and make sure the heaviest part is about 1 inch in front of the rear axle. This is the most important step. Science shows if you do this correctly, you will beat a Pinewood Derby car built exactly the same — except with the weight toward its front — by 4.6 car lengths. It works because the farther back the weight is, the more potential energy you have because your center of mass is higher up on the track. (Don’t put it too far back, or your Pinewood Derby car will become unstable and pop a wheelie.)

2. Use lightweight wheels. This is illegal in some races, but if it’s not in yours, this is a must-do step that will give you a 2.1-car-length advantage at the finish line versus a car with normal wheels. It works because heavy wheels take away from the kinetic energy (the energy something has due to its motion), which makes the Pinewood Derby car slower.

3. Use bent polished axles. Bending your Pinewood Derby car axles with a bending tool will make the wheels ride up against the nailhead, which creates less friction than if the wheel is bouncing around and rubbing against the wooden Pinewood Derby car body. See video above for details.

4. Railride. Railriding means you steer your Pinewood Derby car into the center guide track just enough that you keep the car from bouncing around. This helps reduce friction and saves energy for speed. See video for details.

5. Create a Pinewood Derby car that is reasonably aerodynamic, meaning its design cuts down on drag caused by air. No need to get crazy here, but simply having a wedge-shaped Pinewood Derby car instead of the standard block out of the box will equal a 1.4-car advantage at the finish line.

6. Ride on three wheels by raising one wheel off the track. (Check your pack’s Pinewood Derby rules to make sure this is allowed in your race.) You will move faster if you have to get only three wheels rotating, giving you a 1.1-car advantage over an identical Pinewood Derby car riding on four wheels.

7. Use lots of graphite. There isn’t a big difference in types of graphite, so buy the cheap stuff and use as much as possible. Be sure to get plenty around each wheel and on the axle.

It works! After my research, my son and I wanted to do one final test to prove that this is a good list. So we built a simple Pinewood Derby car using this list in 45 minutes, and we beat the fastest Pinewood Derby car in our local race by two car lengths. Turns out, science works!

Meet Mark Rober

Mark Rober worked as a mechanical engineer at NASA for nine years. During this time, he worked on Curiosity, a car-sized robot that left Earth in 2011, landed on Mars in 2012, and has been exploring, conducting experiments and sending back pictures ever since. Now Mark makes high-tech Halloween costumes.

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#### 13 Comments on Use Science to Build the Fastest Pinewood Derby Car

1. While I appreciate the link between science and Derby success, unless these techniques are readily achievable by the average 6-10 year old, it seems more about the parent need to win than the Scout’s involvement and enjoyment.

2. Rail running is illegal??? Man where is that at?? Graphite is messy, gets all over nice paint jobs, track, and possibly harmful if breathed uhhgg thank God for Krytox for lube. Finally got our District on board for allowing its use since its sold in the scout shops around here. Hollow out bottom of a 3/8 inch car body and use tungsten cubes foe weight is way to go.

3. Almost everything is illegal. There should be bigger disclaimers, especially for new parents!

4. Somehow, this just does not go with my idea of a Cub Scout built race car. Sounds like Dad did most of the work!

5. Remember there are more ways to win besides just being first. My sons tended to focus on design and often were awarded ribbons for “coolest car” etc. The best part for me was the shared experience of manufacturing the car.

6. I did all this spent over 100 dollars on the car. It still failed

7. Rules I read say canted axles are allowed.

• There is no way this cost \$100. We used graphite \$5, weights \$5, stickers, \$2, paint at the house and a saw. Put weight 1 inch in front of rear axle and that was it. My daughter won every race.

8. Speed Wizard // January 11, 2019 at 8:10 pm // Reply