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

1. With all the finessing of the cars, has anyone thought to add magnets, small motor…etc. I mean, speed tricks should be about polishing the axles, weight, aerodynamics, and de-burring the wheels. Everything else gives an unfair advantage to kids whose parents aren’t able or don’t help their scout. When your bent axle, three wheeled car wins the race, you should be really proud.

2. Science wins the day. Wedge with weight placement mentioned above and graphite allowed my daughter to win her Derby. Thanks

3. If it’s the BSA Pinewood Derby, why would there be different/separate rules by district?

4. Our Pack leader sent the video to everyone. No mention of any issues with the rules. This is our First year so we followed the video almost 100%. We will see how we fair next weekend. If everyone does it then it should be very interesting.

5. Firehouse Mouse // January 17, 2019 at 9:21 am // Reply

Funny how important pinewood Derby car ravaging is. Love that the video includes stem- the science and physics behind the scenes that gives a competitive edge. What a great way to include science and make it fun.

6. After 17 years of building pinewood derby cars, I find this is a complete list of speed secrets. If a mom can accidentally drive a nail into a pinewood derby block at an angle then you cannot outlaw rail riding, 3 wheel, or angled axles. The only secret to add is put your car on a treadmill for many hours adding graphite every 20 minutes.

7. 3rd place years ago - with MY own car // January 16, 2019 at 11:03 pm // Reply

Let cubs truly build their own cars and be proud of what they did, regardless of 1st place or last. Let the dads or moms do as much as they want but on their own cars in SEPARATE PARENTS’s division.

8. We built an alignment jig, still have it. Which would allow us to set the wheels at the optimum angle, so the car would run on the edges of the wheel. When we went to the derby the we always set the car and carried the car on the jig. only time it came off was when it was ran.The axle and wheel polishing probably did the most in gaining speed. My oldest son did the best job of polish and prepping the wheels and axles.

• This is a educational event.. if you’re telling the kid to do whatever that defeats the whole purpose. They should be researching and learning the science that’s involved. Other wise its simply play time.

9. As a winner of 3 in a row, my son’s simple wedges proved aerodynamics don’t mean much. There were other cars more aerodynamically designed. They aren’t going fast enough to matter on aero. Polishing the AXLES (with a lot of graphite) is the secret. Be sure to polish down the underside of the head of the nail — assuming your rules require using the standard nails that come with the block kit.

10. Move the center of gravity as far back as possible.

11. 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.

12. 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.

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

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

15. 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.

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

17. 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.

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

• My son won first place overall—twice!—using these tips. It redeemed me as a self-sufficient Navy mom after my older son tied for last place in his first derby. (I know, why would they even keep track?)

19. Some of this stuff is illegal in my pack

• Most of it is illegal in our District, hence, our Pack, which follows District rules to flow through without rules incidents at the District race.

20. This video is great!!! My son and I used his formula and won 3rd overall and 1st at sectionals for tigers. This year we are looking to make it even better. Dads need to watch and follow.

21. the wild one // December 11, 2018 at 8:55 am // Reply

22. no… just no

23. hopefully this works.

24. it does not work

25. I think it was good and i will try to follow his ideas!

27. I’m using your site for a project for an engineering class. Your site is the best site by far for my project. Thank you!

• Too bad all of the advice except weight placement makes the car illegal in any organized races.

• Reasonably aerodynamic is illegal in your race… wow tough rules.
Only light wheels is illegal for the Northstar council everything else is ok.

28. Used the tips in this video and others by this guy to help my son build our first ever car and destroyed the other cars. Finished first in every heat.

29. Great tips Mr Rober!

30. Disappointed // January 21, 2018 at 11:37 pm // Reply

It doesn’t work. I did all of these tips and got destroyed by crappy store bought cars. I really trusted the science but it let me down

• Is it possible you did something wrong. I used everything and we did great

• It is store bought cars NOT Cub made…that is the difference….. family fun is 90 percent Winning with store bought cars is missing the whole purpose of scouting….just feel sorry for them, they will miss half of our purpose on University Earth Life

31. the blonde bomber // December 21, 2017 at 4:34 pm // Reply

Mark Rober (the guy who is behind this) made the worlds largest nerf gun and it is on youtube

32. you cant railride

33. i tried this and i won

34. my race requires a 4-wheeler!!!!

35. this is amazing

36. I’d like to see the evidence that a wedge shape car can give you anywhere near the lead claimed in this article. The test results I’ve seen in other scientific tests have pointed to aerodynamics being of relatively low importance in these races.

37. Proud Bear Den Dad // February 24, 2017 at 8:34 pm // Reply

My son and I watched the video at built our cars (we had a parent’s divison too) and both won first place. Proud of him for understanding how to apply the knowledge he gained from Mr. Rober’s video. Proud to watch him succeed with his own work.

38. My son watched the video and really understood the physics. He took the time and balanced the weight and aligned the wheels as in the video. He won(earned) 1st placed in his Pack with the work he put into his car.

39. Loved the article. After three sons with lots of top 5 finishes but no first place, my youngest son just won our derby today. Our first step before we did any work in the garage was watching this video. You finally convinced me to try the three wheel design. We should have done this eight cars ago.

40. Awesome!

41. and...D_R_O_O // January 15, 2017 at 1:38 pm // Reply

I am so gonna win pinewood derby… or at least a gold medal with this awesome video. Thanks, Mark!

42. and...D_R_O_O // January 15, 2017 at 1:34 pm // Reply

Rail riding is probably illegal.
Wedge is probably the best easy design.

43. That video is going to help me and my brother win this!

44. Percy Jackson // December 24, 2016 at 11:33 am // Reply

Wow!

45. American Fool // July 28, 2016 at 6:43 pm // Reply

This advice is good, very similar to what my son and I did with his cars, and we had very fast cars. I taught my son to drill the rear axle holes at a slight angle (after filling the slots with putty). This way you don’t contort the axle after getting it all polished and shiny!

46. Rail riding is difficult if you are not allowed to raise a wheel, but you can still steer the car mildly into the rail with the front wheels. Keep the back wheels off the rail (this can be done by slightly indenting the front wheels. Also, rather than bend the nail, I like to drill a guide hole for the rear wheels that is just slightly angled (I fill in the slots with putty). Same effect, but less chance of messing up your nicely polished axles.

47. I think the video was very helpful

48. Advisor 1012 // March 14, 2016 at 7:44 pm // Reply

Rail riding will get you kicked!

Use regular unbent axles