The Detonator

The Detonator

Pinewood Derby Times
Volume 7, Issue 4
November 14, 2007

In this Edition:

- Editor's Notes

- Feature Article - Credibility of the Race

- Humor

- Car Showcase

- Memory - Fight the Good Fight

- Q&A

Editor's Notes
Reader Feedback

From Matthew Hunter regarding "Is Your Finish Line Providing Accurate Results?" in Volume 7, Issue 2:
"Last year, we stepped up and volunteered to run our District Pinewood Derby. We were at a mall and did not set up in the same area as the previous years. The mall volunteered a wide area where one of the stores had gone out. We set up late the night before and ran the race in the morning. Every thing was going fine until the middle of the Bears' race when we noticed that the race wasn't being scored right. We took a time out and tried to troubleshoot what was going on. What we found out was that the finish line was set up directly below an atrium-type window in the roof. Once the sun had risen to the right angle, the glare off the track was reflecting into the light sensor. We puzzled over that for a while until my wife went to the car and got a big golf umbrella. We placed it over the finish line and finished the race without a problem. Needless to say, the next time we run the race, we'll go in the opposite direction."

From Stan Pope: "That was a great feature article on 'Effect of Wheel Weight on Performance' in Volume 7, Issue 3. The experiment was well designed in that the total car weight and car's center of mass were held constant throughout the test, and that variables such as different wheel quality and different wheel frictions were avoided by using the same wheels throughout. But I'd like to add the following observations on the wheel weight question. It is not the wheel's weight, per se, but the wheel's rotational inertia that drains away the car's energy. Rotational inertia is affected by wheel mass and distance of the mass from the center of rotation. A gram of mass in the wheel rim causes much more rotational inertia than a gram of mass in the wheel hub. The inertia varies with the square of the distance from the center of rotation. A gram of mass 10 mm from the center causes 4 times as much inertia as that same gram of mass only 5 mm from the center. Thus, it is certainly advantageous to move rim mass to the wheel hub."

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Feature Article

Credibility of the Race

(Updated from the original article published in Volume 1, Issue 9, January 23, 2002)

As a derby leader, I am very much concerned with race credibility. Every participant in a derby wants to know that the race is completely fair, so the derby leader must take every precaution to ensure that there is no bias in the race. To the race participants, the race procedures must be above reproach.

Race bias can come in three ways:

To run a race with integrity, the derby leader must make every effort to eliminate all of these forms of bias.

The purpose of this article is to provide you with guidelines and practical steps you can follow to keep your race above reproach. Remember that the goal is not just to eliminate race bias, but to also eliminate any perception of bias by the audience and participants.

Race Rules

The first and very important area to consider are the race rules. Most organizations provide very simplistic rules that are incomplete, and that can be interpreted in many ways. Therefore the rules must be:

Rule 1 is very specific as to what can be done with the wheels. A car with narrow wheels, H-Tread wheels, etc. would clearly be disqualified from a race using this rule.

On the other hand, rule 2 is ambiguous and could lead to problems. A car with narrow wheels or H-Tread wheels should be allowed to participate, since the rule does not disallow narrow wheels.

As an example of the need for complete and specific rules, one person wrote to me stating that they wanted to remove material from the wheels. This particular technique was not mentioned in their rules, so they asked a race official (not the head official) if the technique was allowed. The race official gave them permission. But at the weigh-in, the head official disallowed the technique, and the car was banned from the race. This was clearly a case of unintentional bias (hopefully it was not intentional), and could have easily been eliminated with clearly written rules.


The next area to consider is the check-in. The purpose of the check-in is to register, inspect, and impound the cars. This procedure must be done in a fair and consistent manner. Here are some specific ways to eliminate bias in this phase of the race:

As an example of this problem, during one check-in our scale was located under an air-conditioning duct. Whenever airflow was present, the scale would read a slightly greater weight! Once we realized the problem, we covered the duct. But we had to reweigh all of the cars to make sure that everything was fair.

Car Storage

If your check-in occurs immediately prior to your race, then storage is not an issue. But in some races the race evening is shortened by holding the check-in on a prior night. The cars are then stored until the race.

To ensure that our race is above reproach, two non-related officials store the cars, and then put a "seal" on the storage area. On the night of the race, the same two officials check to make sure the seal is not broken. The seal can be as simple as an adhesive label placed across the opening of the storage cabinet. The two race officials then initial the seal.

This process may seem excessive to you, but if a parent ever asks how we ensure that no tampering occurs while the cars are stored, we are ready with a good answer.

Race Format

Race formats can also introduce bias. We have covered race formats in much greater detail in other articles, however here are some basics.

Car Handling

One of the worse things that can happen in a race is for a child to drop their car. But even worse is for one of the race officials to drop (or even mishandle) a car! Thus, use a race procedure whereby the officials rarely if ever touch one of the cars. This means that each car owner picks up their car from the staging area, places the car on the track, and then returns the car to the staging area at the end of the race. In the case of very young or disabled car owners, parents or a sibling can take on the car handling responsibility.

Finish Line


I realize that to implement all of the above mentioned precautions will take extra work on the part of the race official. However, you must ask yourself one question. If a parent came to me and said, "My child's car is being treated unfairly," what would you say? If you have implemented all of the precautions above, you can ask the person to clarify, and then explain how the precautions you have taken ensure that each entry is treated fairly. But if you have not taken the necessary steps to eliminate race bias, you will find yourself in a tough situation.


The Pope just finished a tour of the East Coast and was taking a limousine to the airport. Since he'd never driven a limo, he asked the chauffeur if he could drive for a while. The reluctant chauffeur pulled over along the roadside, climbed into the back of the limo, and the Pope took the wheel. The Pope then merged onto the highway and accelerated to over 90 mph to see what the limo could do.

Suddenly, the Pope noticed the blue light of the State Patrol in his side mirror, so he pulled over. The trooper approached the limo, peered in through the windows, then said, "Just a moment please, I need to call in."

The trooper called in and explained to the chief that he had a very important person pulled over for speeding.

"How do I handle this, chief?" asked the trooper.

"Is it the Governor?" questioned the chief.

"No! This guy is even more important!"

"Is it the President?" asked the chief.

"No! Even more important!"

"Well, who the heck is it?" screamed the chief.

"I don't know, sir," replied the trooper, "but he's got the Pope as his chauffeur."

Car Showcase

Speed Trap: Chris Hailey

This is my son’s 2007 pinewood derby car called "Speed Trap". He got the idea from this past winter when we had a little mouse trouble in the house. We went to Lowe’s, bought some mouse traps, and solved our mouse problem. But my son thought it would be funny if he raced a mouse trap this year. So, we studied a standard mouse trap, purchased some materials from our local craft store, and drew the initial idea on paper. It actually took us two tries to build this car, but we both think it turned out great! Hopefully, it will perform as well as it looks. If not, he hopes to win a design award.

Batman: Kerry Bybee

The inspiration for this car was the Batman car of the movies, but my son Brady wanted a pinewood derby car that looked like his Hot Wheels Batman car. So with a copier I enlarged the profile of the car to pinewood derby size. I used a scroll saw to cut out the car, and then a Dremel tool to shape it. It then took a lot of fine sanding to shape the wings right. I have built a lot of cars that have won and lost, but the Batman car stays consistent; it has never placed below 2nd at any race.

This car raced in February in our local pinewood derby and won 1st place. In then took 1st in a district race, 2nd in an RA race, and then 1st place in a local RA race. It also won 1st place in an Outlaw race; I added weight in the back between the high fins to reach the higher weight limit.

Velocinator: Shannon Davis

This is a prototype of the Velocinator(1) which my daughter ran in a Parent/Sibling race in April 2007. This was our first experience with the needle axle wheels. The car was very fast, winning the first two heats. It then slowed down and took second the last two heats. We later found out that the axles had bent, either from the force of the run or from the abrupt stop. After the race we bent then back in place and made a test run. It immediately went back to the original performance. Oh well, a lesson learned!

1The Velocinator is available as a kit

Share Your Pinewood Derby Car Creation
Do you have a car you would like to 'show off' to our readers? If so, send us a photo of your car along with a brief description of any special features. Also, please include your full name. If selected, we will include the photo and description in this newsletter.Please e-mail photos to:

Photos must be sent by e-mail in JPG format (minimum size of 640x480 - maximum size of 1280 x 960). Please shoot photos from the front left of the car, similar to the orientation of the cars shown above.

Send only one photo per car, unless an additional photo is needed to adequately show a feature. Also, only one car per subscriber per year please. Thanks!

Pinewood Derby Memory

Fight the Good Fight

I am a divorced dad who has fought the good fight since my son was 3. He is now 10. This past December I gained additional custody of my son and I had an extra night that I could give to a scouting type event. With only a Wednesday night to devote to this, the only option for us was the Royal Ambassadors at my church. Luckily for us, they had not had their race; so when we joined the group in January we got to pick out our car kits the first Wednesday night.

I polled my colleagues at work, and gathered ideas for how to build a fast car.

My son added pressure by saying, "Dad, can we really do this?"

We sanded. And sanded. And sanded. We primed. And primed. And primed. We weighed, drilled more holes, sanded and primed again and again. Three of the four post office locations we used to weigh our car-in-progress had scales that appeared to be off by one to three-tenths of an ounce. By race day, April 14th, 2007, I was not sure if we could do this!

We buffed and buffed the axles with jeweler's rouge until they shined like new money.

We helped set up the race track the night before the race; so we tried out our cars. While we were fast, it appeared we would not be the fastest.

On Saturday afternoon we took the wheels off one last time and buffed again. This time we sprayed the axles with silicon and then applied graphite.

At the race my son won 1st place for speed in his division and 1st place in design. I won 2nd place in speed in the adult division (I lost to an ex- cub scout leader who now builds cars with kids that have no father involved -- good guy to lose to!) and 1st place in design. Overall we were 2nd and 3rd in speed; with he and I separated by one-thousandth of a second and seven thousandths behind first place.

Most of the time I wear a fake smile because the past several years have been a struggle. As I said, I/we have fought the good fight. But as Jeff's name was called for having the fastest car for his first award, I smiled a real smile. Jeff smiled as well, and when he got his second trophy he had a tear in his eye. We did it!

Next year is our last year to race. While the above story highlights a win, the experience Jeff and I had being competitive with other experienced kids and adults grew our relationship.

Thanks for the opportunity to share this story; I'll be using your products next fall.

Dennis Hollingsworth

Share Your Pinewood Derby Memory!
I am sure there are many stories to share. Please jot down your humorous, unusual, sad, or heart-warming pinewood derby tale and send it to:

If your memory is used, you will receive a $10 coupon in May of 2008.

Don't worry about literary polish. We will edit as needed. Also, please read our Submission Policy


Is there a national pinewood derby?

Not really. A year or so ago, BSA had what they called a national derby, but it was really a design competition. Dremel/Lowes has also had national design competitions in the past.

There are, however, several racing leagues which have "proxy" races. That is, cars are shipped to the race, the results of the race are posted on the Internet, and the cars are then returned. People can travel to the races if desired.



PWD Racing

When you are making low-profile car, like your Wing design, how do you attach the weights?

The bottom of low-profile cars usually has rectangular "pockets", deep enough to accommodate the weight. If tungsten beads are used for trim weighting, a series of 3/16 inch holes are drilled into the bottom. The weights are glued into the pockets with epoxy adhesive1.

Should the tread surface of the wheels be lightly sanded for better surface traction?

Lightly sanding the wheels is good advice, but it is to remove surface imperfections, not to increase traction. In fact, the wheels should be somewhat slick to minimize friction. I suggest sanding the wheels with 600-800 grit wet/dry sandpaper (use it wet). If desired, you can then rub graphite onto the tread surface of the wheels. Just make sure to wipe off the excess with a rag.

1Epoxy adhesive is available Here

Do You Have Questions that Need Answers?
Do you have a pinewood derby-related question? If so, send your question to: We answer all questions by e-mail, but not every question will appear in the Q&A section of the newsletter.

Back Issues

Are you a new subscriber, or have you missed some of the previous newsletters? Don't miss out!

We have just added an index of all newsletter articles since the first edition in October of 2001. We hope this helps you find information more quickly. To view the index Click Here

All of the issues for Volumes 5 through 7 are posted on our web site:

Volume 7

  1. Volume 7, Issue 4

  2. Volume 7, Issue 3

  3. Volume 7, Issue 2

  4. Volume 7, Issue 1
Volume 6

  1. Volume 6, Issue 1

  2. Volume 6, Issue 2

  3. Volume 6, Issue 3

  4. Volume 6, Issue 4

  5. Volume 6, Issue 5

  6. Volume 6, Issue 6

  7. Volume 6, Issue 7

  8. Volume 6, Issue 8

  9. Volume 6, Issue 9

  10. Volume 6, Issue 10

  11. Volume 6, Issue 11

  12. Volume 6, Issue 12

  13. Volume 6, Issue 13

  14. Volume 6, Issue 14

  15. Volume 6, Issue 15
Volume 5

  1. Volume 5, Issue 1

  2. Volume 5, Issue 2

  3. Volume 5, Issue 3

  4. Volume 5, Issue 4

  5. Volume 5, Issue 5

  6. Volume 5, Issue 6

  7. Volume 5, Issue 7

  8. Volume 5, Issue 8

  9. Volume 5, Issue 9

  10. Volume 5, Issue 10

  11. Volume 5, Issue 11

  12. Volume 5, Issue 12

  13. Volume 5, Issue 13

  14. Volume 5, Issue 14

  15. Volume 5, Issue 15
Issues from the four previous seasons are available in four formatted volumes, ready for immediate download. To find out more, Click Here.

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Randy Davis, Editor, Pinewood Derby Times

Copyright ©2007, Randy Davis. All rights reserved. Please do not reprint or place this newsletter on your web site without explicit permission. However, if you like this newsletter we grant permission, and encourage you to e-mail it to a friend.

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