The Truck

The Truck

Pinewood Derby Times
Volume 7, Issue 9
January 23, 2008

In this Edition:

- Editor's Notes

- Feature Article - Setting the Gap for Performance

- Humor

- Product Showcase

- Car Showcase

- Memory - Wheel Loss

- Q&A


Editor's Notes
Reader Feedback

We received quite a bit of feedback on our article on pinewood derby for Boy Scouts. Here are are two representative e-mails.

"I just received your latest issue and I saw the letter asking about Boy Scout derbies. Well, of course your troop or patrol can do them. Boy Scout troops if run properly are boy led. They can do whatever they plan to do (within limits). Our scouts have not forgotten the fun of Pinewood Derbies and about every two or three years they plan to have one. Once again, their idea, and it is set up in accordance with their rules (or lack thereof) in our troop. As they have structured it in the past you can race old cars or build a new one. The only rules are under five pounds, no rocket or other engines, and it may not interfere with other cars down the track. That is their version from two years ago. The versions could be and would be endless depending upon the ideas of the boys and the limits imposed by the adults. In other words, yes, you can have a derby. Perhaps the kids have not thought about it - yet." Janis Tipton-King

"I think that your letter to BSA was well written with many salient points. I would, however, like to suggest that for Scouts, the pickup truck kit that we have in Canada, would be a nice step up from Cubs. In our group, we have Beavers build Beaver Buggies, Cubs do Kub Kars, and Scouts make pickup trucks and 18-wheelers. We leaders and parents have made all of them and we have a blast." Deryck Robertson

Can We Help?
If we can help you in any way with your pinewood derby project, or if you have any feedback regarding this newsletter, please contact us at: info@maximum-velocity.com
Maximum Velocity Car Kits

If you are planning a race and are not required to use a specific kit type, our MV Basic Car Kit is just what you need. These attractively priced kits are equipped with:

  • Quality Block - Unlike the blocks provided by some organizations, our blocks are soft, northwestern pine blocks, cut precisely to 7 inches long, 1-3/4 inches wide, and 1-1/4 inches tall. These dimensions, as well as the axle slots accurately duplicate the dimensions of standard pinewood derby blocks from BSA and PineCar.


  • Simple Axle Preparation - Don't worry about filing off flaws, or losing hub caps. Our Speed Axles have no burrs or crimp marks, and install without hub caps. With or without polishing, they are ready to go. We supply five, so you have a spare.


  • Quality Wheels - Forget cheap, out of round wheels. We supply top-quality, PineCar-brand wheels to give great performance.
So, if your organization does not mandate a particular kit type, consider our Maximum Velocity Car Kits


Feature Article

Setting the Gap for Performance

One of the most common questions I am asked is, "How much room should there be between the car body and wheel hub?" My first answer is, "Well, our Pro-Axle Guide, Alignment tool, and the Gap Gauge in our speed kit will set the spacing for you." Then the next question is, "If I don't have those, what should I do?" My response is then, "Try using a credit card. It will set a gap that works."

Of course, these responses beg the original question of, "How much room should there be between the car body and wheel hub?" Or better yet, "What is the optimum gap?" I have heard and read some distinctly different opinions on this topic. Several people have said that they set a fairly wide gap in an attempt to minimize the contact between the wheel hub and car body (and also to simplify making the needed observations when performing alignment using the Shim Method). On the other side, Michael Lastufka's DOE (Design of Experiment) tests showed that best performance is attained with a small gap.

Which is right? I can understand the thought process behind the wider gap; less opportunity for contact. But, I also recognize that a wider gap allows the car more "wander room", thus permitting the car to travel a greater distance during its trip down the track (remember that the shortest distance between two points is a straight line).

Experiment Setup

So, I decided to set up an experiment to measure performance versus the wheel to the hub gap. One car, one set of wheels, and one set of axles was used throughout the experiment. Outlaw wheels where used to minimize the effect of guide rail and track surface contact. Krytox 100 was used as the lube to minimize break-in and maximize the consistency of the runs.

The following gaps were tested. A set of feeler gauges were used to set the gaps.

To minimize experimental variance, the axles were inserted, the heads were marked at the 12 o'clock position, and the axles never removed from the car. As each gap setting was made the axle was adjusted and the axle heads were checked to make sure that the mark stayed at the 12 o'clock position.

In order to minimize the effect of lubricant breakdown, the test was limited to five heats per gap setting (total of 35 heats). On the first pass, three heats were run per gap, going from the largest gap to the smallest gap. Then two additional heats were run going from the smallest gap to the largest gap. The high and low runs per gap setting were discarded, and the three remaining runs averaged.

Experiment Results

As can be seen in Figure 1, the smaller gaps outperformed the larger gaps. Note that there is no real difference in performance between the three smallest gap settings (the difference is statistical noise). However, as the gap increases, performance decreases in an almost linear fashion.


Figure 1 - Wheel to Car Body Gap Test Results

Conclusion

So what is the bottom line? Clearly the gap setting does affect performance. For best performance, use a small gap setting (such as provided by the available gap tools). If one of these tools is not available, then use a credit card (which is typically 0.030 inches).




Humor

Two brothers were always getting into trouble in their neighborhood. The people in the neighborhood started complaining to the parents about the boys. So the boy's parents decided to have their priest talk to the boys.

The priest asks to speak to the boys alone, requesting to see the youngest first. The young boy comes in and sits at a large table across the room from the priest.

The priest looks at the boy, points at him and, trying to emphasize that God is everywhere, asks, "Where is God?"

The boy looks around the room and back at the priest and says nothing.

Again, the priest points at the boy and in a louder voice asks, "Where is God?" The boy says nothing.

The priest walks around the table, pointing inches from the boy’s face and asks again, "Where is God?"

The boy jumps out of his chair and runs out the door. The boy runs right home, grabs his older brother and says to him, "We are in BIG trouble!"

His brother replies, "We haven't done anything!"

The younger brother replies, "God's missing, and they think we did it!"




Car Showcase

Kevin Harvick Car: Brian & Brianna Fenech


This car was my daughter Brianna's (age 11) first ever submission for her April 2007 Awana Grand Prix race. The paint/decal scheme is similar to NASCAR's Kevin Harvick. Kevin was the winner of the 2007 Daytona 500. Brianna proudly wore her matching Kevin Harvick NASCAR t- shirt for the Awana race. The car features an extended wheelbase and super wedge design. All the weight is located near the rear axles, the is 5.0 ounces. The wheels are race ready graphite coated slicks. The axles were smoothed and grooved to reduce friction and hold additional graphite lube to endure the race. The car raced a total of 8 Class races. It sped to 1st Place - Top Speed in Class, then Top Speed Overall to beat all competition, including parents. The race car also garnered 2nd place in class for design. We're looking forward to start building our 2008 Awana Grand Prix racers.

The Beast: Vaughn Lester


My car received its nickname from an uncle who thought the design would demolish everyone else. This was our first pinewood derby and we only gained interest by watching "Down and Derby". Anyway, after I finished watching the movie I got on the Internet and happened to fall upon your website. I quickly soaked up all the information and designed my car. I then built a prototype and was happy with the result. I made a few changes and this is what I came up with. I then realized that there were still four months till the race and I was already prepared to build the race car and race. However I had to wait two months before I received the kit and then I built my car. It took me a week to finish the sanding and then I started painting. I sprayed four coats of white two to three times a day for the last week before the event, until it had twenty plus coats of paint!!! I didn't have any graphite yet but I needed the wheels on to participate in the test runs. I was amazed how much better it performed than most of the other cars (nobody else had lubricant either I am glad to say). Now to fast forward to race day. Excitement builds as cars start coming and the race hour draws near. I am participating in the leader's and dad's race so I have a few stiff competitors. I placed 3rd overall, and I lost to someone who I had given tips from your site to (my mistake!).

Green Machine: Andrew Lester


This was my son's 2007 car. He was a Wolf and we used some of your matched wheels, tungsten weights, drilled block, and some tungsten putty. He ended up 1st in Wolf at the Pack level, 2nd in Wolf at District Semi Finals, 1st overall at Semi Finals (don't ask how this works, we can only blame it on less than perfect brackets), and 2nd at the District Finals.

Help! We are nearly out of cars for the showcase!

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:
info@maximum-velocity.com.

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 this car:


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

Wheel Loss

Last year I helped my grandson build a pinewood race car. I've helped him build other cars before. Anyhow this time we thought we would try a lightweight wheel, weighing about 1.2 grams.

Well, on race day he won his first race by half a car length. On his second run he again won by about half a car length, but on hitting the stop his right front wheel came apart. We replaced that wheel with a standard wheel out of the BSA kit. Over the remaining runs he lost the left front wheel then the right rear wheel. Of the 27 cars racing he still came in second!!

When he and the other two boys where having their picture taken holding the car and trophy his left rear wheel, last of the light weights, fell off!!!

Bob Flood

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:
info@maximum-velocity.com

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




Q&A

We're considering purchasing an aluminum track for our Cub Scout pack, but are uncertain as to whether to buy a four or six lane track. We have about seventy boys in the pack. What are your thoughts?

I would opt for the four lane track for the following reasons:

  1. Each car should race at least once in each lane. So, with a six lane track, more heats are required.


  2. The time for the actual race is the same, but it takes longer to stage six cars than 4four cars.


  3. There are more ties on a six lane track. This makes the event last longer.
I suggest you use the funds to get a longer four lane track (forty to fifty feet). A longer track means:

  1. More seating space


  2. Fewer ties
Just make sure you have the space to set it up!

When using the tungsten plates, is there adequate clearance without recessing the weight?

The plates are 1/16 inch thick. If you use Cub Scout standard slots or axle holes drilled at 1/8 inch off the bottom (measured to center of hole), you will make the 3/8 inch clearance. If you use deeper slots, or axles holes set higher on the block, you may or may not make the clearance. Paint thickness will also affect clearance.

To be safe, you can create a pocket to recess the plates.

Do You Have Questions that Need Answers?
Do you have a pinewood derby-related question? If so, send your question to:
info@maximum-velocity.com. 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 1

  2. Volume 7, Issue 2

  3. Volume 7, Issue 3

  4. Volume 7, Issue 4

  5. Volume 7, Issue 5

  6. Volume 7, Issue 6

  7. Volume 7, Issue 7

  8. Volume 7, Issue 8
  9. Volume 7, Issue 9
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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Please read our submission policy.




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Randy Davis, Editor, Pinewood Derby Times
E-Mail: info@maximum-velocity.com


Copyright ©2008, 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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