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Pinewood Derby Times
Volume 15, Issue 5
December 2, 2015

In this Edition:

- Editor's Notes

- Feature Article - Offset Weight Placement - Part 2

- Humor

- Product Showcase - Everything - 10% Off

- Pinewood Derby Car Showcase

- Memory - Up In Flames!

- Q&A



Editor's Notes

Reader Feedback
A timely note from Butch Weathers: "I was standing out in the cold here in New Jersey with my daughter last weekend trying to figure out which strings of outdoor Christmas lights worked and which would need to be fixed. Once we'd replaced any obviously broken or missing bulbs the next task was to methodically replace each bulb in a string that wasn't lighting up with another one. Some of the bulbs came out easily but many were stubborn. My daughter said to me, 'I know you have a tool for everything, how come you don't have one to take the bulbs out?' So I went to my workshop looking for something that would work. I first grabbed a pair of diagonal cutters which I thought could work if I didn't put too much pressure on them. Then I saw the Axle Extraction Pliers I bought from you a few years ago. They were perfect; they could have been designed for just this task! I happily went back outside and gave my daughter the 'bulb puller tool', and her faith in me was restored."

Inventory Clearance Sale
We also are clearing inventory on several items including:
  • Two special purchase tungsten weights: Mini-tungsten Weights and Round End Tungsten Plates.

  • Two Car kits: the Accelerator, and the Vaccinator.

We don't have many left, so don't delay. Click Here to find our clearance items. Don't miss out on the great prices.

MV Basic & Wedge Car Kits

If you are planning a race and are not required to use a specific kit type, our MV Basic or Wedge Car Kit are 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. Our MV wheels are top-quality wheels. You will not be disappointed with the quality of these wheels.

So, if your organization does not mandate a particular kit type, consider our MV Basic Car Kits or MV Wedge Car Kits

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


Feature Article

Offset Weight Placement - Part 2
By Randy Davis

Back in 2011, I did an experiment on side to side weight placement1 which was documented in Volume 10 Issue 8. In that experiment, on a three-wheeled car the left-to-right center of gravity was shifted left, then right, and then evenly balanced on the rear wheels. The effect of alignment was then checked for each weight position. The result was that there was no meaningful effect on the alignment of the car due to the left-right position of the weight.

Further Consideration
After some consideration I decided that the experiment was not complete. First, I did not measure the actual performance of the car on the track. Secondly, the balance point of the car was fairly conservative (less weight on rear wheels).

So, I decided to modify the test car and redo the experiment with track testing. I decided to eliminate the left shift of the weight and focused on Center Weighting and Balanced Weighting.2


Figure 1 - Original Test Car

The original test car held four COG weights, two in each side hole, and a small amount of trim weight just in front of the rear axle.


Figure 2 - New Test Car">

The new test car has four COG weights, one in each side hole, and just over one ounce of weight just in front of the rear axle. This results in a more aggressive center of gravity (3/4 inch in front of rear axle), and a greater amount of side-to-side adjustment.

Experiment Setup
The car was equipped with polished BSA Speed Axles and Pro-Stock Speed Wheels, and lubricated with Krytox 100. The front dominant axle was bent and adjusted for railing riding,

When Center Weighting was configured, there was 2.54 ounces on the left-rear wheel and 1.64 ounces on the right-rear wheel. When Balanced Weighting was configured, there was 2.09 ounces on both wheels.

Results Each configuration was run ten times, and the times were averaged and a standard deviation calculated.

In harmony with the first experiment, the results showed no measurable difference between Center Weighting and Balanced Weighting.

  2.553 - Center Weighting Average, .0017 Std Dev

  2.554 - Balanced Weighting Average, .0029 Std Dev

Conclusion
So, I think I can just paraphrase the conclusion from the first article. Placing the weight such that it is evenly distributed on the rear wheels is the theoretical correct technique. However, a centered weight placement will not have any effect on the performance of the car.

1For a discussion as to why the left-right weight placement is theoretically of interest, please refer to the original article.

2"Center Weighting" places the weight in the left-to-right center of the car body. "Balanced Weighting" places the weight so that the rear wheels have an equal weight load.



Humor

When my three-year-old son opened the birthday gift from his grandmother, he discovered a water pistol. He squealed with delight and headed for the nearest sink. I was not so pleased. I turned to Mom and said, "I'm surprised at you. Don't you remember how we used to drive you crazy with water guns?"

Mom smiled and then replied....."I remember."



Product Showcase

  Everything  
10% Off

Do you know someone that needs that special pinewood derby tool or part? Now is your chance to save big.

Through December 9, 2015 (one week only) you can get 10% off your entire order. To take advantage of this limited time offer, use coupon code DEC2NL during checkout.

Important Notes:
(1) The coupon code must be entered in UPPERCASE.
(2) Apply the coupon code after all items are in the cart. If the shopping cart content is changed after the coupon is entered, the coupon code may need to be re-applied before pressing the "Proceed to Checkout" button.



Car Showcase

Today's cars were submitted by Dennis Pemberton

Squished Beetle

My version of a chopped Beetle. I made it at the last minute. It started out with a light blue finish but the spray can was old and I got horrendous "orange peel". So I sanded it down and sprayed two different shades of primer - like a true Rat Rod!

"Oh, I Wish I Were ..."

My wife made this Oscar Mayer Wienermobile. We used a chunk of balsa for the wiener, and the thing still came in at almost 5 ounces.

Bus 64

My entry in the Awana Grand Prix. I had to make the sides out of sheet plastic because even 1/4 inch poplar sides were too heavy. I was not real happy with the motor. The bus was surprisingly stable with so much weight on top.

Batmobile

My daughter's Batmobile. Although it doesn't show very well in the picture, the number 7 is actually the first coat of gloss black, sanded down. I then masked the 7, and shot another coat of gloss black on top. The result was a subtle, shadowy seven.

Share Your Car With Our Readers

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. 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:


For better focus, keep the camera four or five feet away from the car, and then use the camera's zoom to fill the frame with the car. Also, use a solid (preferably white) background for the photo.

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

Up In Flames!

We were building four cars for the upcoming derby race. It was the weekend before the race, and the cars were finally painted. For some reason the yellow paint on one of the cars just didn't seem to be drying.

A dim light bulb suddenly switched on inside my head - I could use the microwave to dry the car! Quickly, I put the car on a paper plate, stuck it in the microwave, and turned it on. I left the room for a few moments, and then all of a sudden I heard a scream coming from the kitchen. I quickly rushed back in and found the car in flames, with the owner (my lady friend's 13 year old) screaming in horror! I quickly shut off the microwave and removed the car. It was rather warm to the touch, the paint was burnt and slightly bubbled, and the 13 year old was crying, (not to mention the stench which remained in the house for a week). With a lot of sanding, repainting, and consoling, we managed to get the car completed on time.

On race day all of the trouble was justified. The car won 1st place for speed in its division and took 2nd place in the design category.

I don't think we will quickly forget the "Flaming Car", and will certainly leave the microwave out of our car building process in the future.

Duane Hittle
Capac, Michigan

Share Your Pinewood Derby Memory!
If you have a pinewood derby story that is funny, unusual, sad, heart- warming, etc., please E-mail it to me.

Don't worry about literary polish. We will edit as needed. If your memory is used, you will receive a $10 coupon in May of 2016.

Also, please read our Submission Policy



Q&A

On most all of your technical reports five inches of steer is used most of the time. This makes the car a "rail pusher" more then a rail- rider. Could a timed test be done using 1, 2, 3, 4 and 5 inches of steer?

Generally, you need a decent amount of drift to make sure the dominant wheel stays on the rail. If it comes off the rail, then the car can become unstable, losing the advantage of rail-riding.

Tracks vary in their quality and setup, so 5 inches over 8 feet is recommended to overcome most track issues. It is possible that on a very smooth and level track the drift could be less. But even on my smooth aluminum track, which is leveled, five inches (and sometimes more) of drift is needed to make sure a car with an aggressive COG stays on the rail. But the amount of drift required is track dependent.

I want to enter a fund raiser event in the outlaw class which allows powered cars. I have a Fan Powered car from many years ago (the orange one). You have the V3 available but I'm not sure if I will be allowed to charge the car prior to each heat. Not sure what the V2 was but I assume it was faster than the version I have. Did the V2 run on a battery or capacitors? Are the V1 and V2 fan powered kits still available?

The V2 was the first capacitor car, with the same sized fan as the V1. The V3 has a larger fan and altered component mounting. Neither V1 or V2 are available.

One solution, albeit a bit ugly, is to use the V3 and mount a 9V battery on top of the car, plugged into the jack. Then the capacitors will charge while the car is staged. Preferably it needs 30 seconds to charge. Note that the weight of the battery may slow it down a bit.

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! All of the issues for Volume 5 through Volume 15 are posted on our web site and can be found using our Newsletter Index.

Issues from Volumes 1 to 4 are available in four formatted documents, ready for immediate download. To find out more, Click Here.




Newsletter Contributions

We welcome your contributions! If you would like to contribute an article, a web site review, or a speed tip, please send it to: info@maximum-velocity.com.

Please read our submission policy.



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

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