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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. (Donโ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 itโ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 isnโ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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#### 58 Comments on Use Science to Build the Fastest Pinewood Derby Car

1. RosieIsAwesome // February 26, 2016 at 8:10 pm // Reply

Girl Scouts are doing this now ๐๐๐

2. pinewood derbyer // February 20, 2016 at 6:51 pm // Reply

HORRIBLE! GOT DISQUALIFIED!

3. a_man_from_around_the_corner // February 9, 2016 at 5:12 pm // Reply

On one of the pinewood derbies I had gone to, a boy had tried out the wedged block trick. What I also heard about what he did was obvious, he maxed out the cars weight, but before, he had baked the block in the oven for a half hour on 350 degrees, making this as light as a feather. Shortly after that, he had taken out parts of the block so that he could replace it with weights, this being on the center balance point of the vehicle. The last major adaptation to his winning car was all of the graphite that he applied to his cantered wheels. For years afterward, he won the derby, making him someone to follow after.

4. Anonymous 123 // January 19, 2016 at 8:07 pm // Reply

Cool tips will use this at derby! !!

5. #7 couldn’t be more wrong. Go ahead and use the cheap stuff and overpack it if you want to lose vs someone who uses good stuff correctly.

6. Also the axles (nails) have a raised edge under the nail head from the manufacturing. Chuck the axle nail in a dremel tool and use a jewelers file or even sandpaper to remove it while the axle is spinning, like a lathe (clamp the dremel to a work bench to make it easier). Then polish that section of the axle. But don’t take off too much metal!

7. epic!!!

8. A wedge with little grooves in it works better than just a wedge. Tried it. I quit a while ago so I don’t care if anyone tries this trick.

9. i’m doing a science fair project, and so far this has worked

10. Random Minecraft zombie // October 15, 2015 at 2:40 pm // Reply

I personoly wouldent do the three weeler thing.
P.S. the cars go to slowly to make airodenamicks
matter.

11. Spaceman Spiff // July 22, 2015 at 1:03 pm // Reply

Some of these sound questionable.

• 3 wheels touching the track creates less friction than 4 wheels. It works.

• Wrong… friction per wheel increases so the net friction is the same. What makes 3 wheels faster is less rotational inertia. There is one less wheel that has to accelerate (radially). This means faster acceleration.

12. If I only knew all this in 1978, I would have placed first instead of second! ๐

13. I gonna try this at the pinewood derby.

14. Is it true

15. Best info ever

16. fast

17. derby master // February 26, 2015 at 6:56 pm // Reply

ill try this

18. that’s nice

19. cool

20. next derby im gunna domanate if i try this ……im exciteded

21. Good Ideas for This Month!!!

22. do you need the special tool to bend the axles?

23. Can you send a picture of the car

24. District competition rules may be stiffer than the Pack rules.
Parent and sibling races may have looser rules since they don’t move on to District.
This is a great video for explaining the principle’s of why all cars don’t run the same.
It may be better at explaining that to some overly competitive parents than to the Cubs.
ALWAYS make sure the Cub has a good time building it…fast or not in the end.

25. awesome

26. Soooooo gonna try yhis๐

27. Interesting!!

28. polishing wheel bore is as critical as polishing the axle, without it friction reduction is marginal..

29. This will help alot!

30. Our Pack provides awards for 1st place, fastest looking and best craftsmanship. We build ours for show. We stand a better chance and the second two! LOL! I have never been able to master the axles.

31. Sounds like less friction is the key!!!

32. Awsome!

33. COOL!

34. Cub Scout Dad // January 6, 2015 at 10:06 pm // Reply

How should the wheels be slanted if all four have to touch the ground? That is one of our rules.

35. Our rules state all 4 wheels must touch the ground at the same time. So what is the best way to slant the wheels?

36. does it work?

37. Nicely done and relevant video to incorporate with STEM requirements. Many thanks!

Riding on three wheels is not allowed in our race. So would that mean that both front wheels should be situated to make the car run into the center track?

39. Wigwag which // January 2, 2015 at 10:32 pm // Reply

Cool
Awesomely way cool

40. Wigwag which // January 2, 2015 at 10:32 pm // Reply

Cool

41. meant to be funny // December 31, 2014 at 10:27 pm // Reply

This stuff is awesome thinking of doing it myself

42. Wolf Den Dad // December 30, 2014 at 6:31 pm // Reply

This has become the new go to video for teaching kids about the physics of pwd. The only thing he really got wrong was the axle bending. The adult pro racers do not bend their rear axles, they drill the rear holes at an angle to canter the wheels. The only axle they bend is the front dominant wheel to adjust steer for rail running. Scouts will most likely also have a hard time to properly get their rear wheels aligned using bent rear axles.

Most of his tips arent tricks and most are legal. Yes the lightened wheels and aftermarket axles are illegal in most scout rules. The other stuff only a few may have extra rules to keep from canting the wheels or only riding on 3 wheels.

Only thing he really got wrong was saying the fastest derby pro racers use bent axles. They drill their rear axle holes at a canted angle. The only axle that is bent is the dominant wheel to adjust the steer. Most scouts will likely not be able to get their rear alignment straight using bent axles either.

44. physics and science is a good way to win

45. Aw2815 Scoutmaster // December 29, 2014 at 10:19 am // Reply

Honestly, some of these tricks are illegal according to our rules. There is other tricks but I am not saying what they are. And there is books on the subject at your council office. ๐

You need to explain the rules to the boys and explain why the rules are there.

46. I would like to thank Mr. Rober for sharing his speed tips and expaining the science behind each one. Very interesting!
More importantly, I would like to thank him for pointing out which tips may be illegal! So it is very important that each Pinewood Derby participant be aware of the rules for their Pack’s race (and District race, too)! It would be a shame for a Scout to have his car disqualified because he followed some illegal procedure when building his car!

47. EG Cub Scout // December 23, 2014 at 6:59 pm // Reply

I know a nother way you can win but i am not telling you.

48. EG Cub Scout // December 17, 2014 at 4:29 pm // Reply

This will be helpful I have one in March 2015