Standard Velocinator

Standard Velocinator

Pinewood Derby Times
Volume 14, Issue 7
December 31, 2014

In this Edition:

- Editor's Notes

- Feature Article - Height of Ballast Weight Vs. Performance - Part 2

- Humor

- Product Showcase - Mini-Tungsten Cylinders - 1 Ounce Free

- Pinewood Derby Car Showcase

- Q&A



Editor's Notes
Help! We Are Almost Out of Car Photos
In order to continue including a Car Showcase section in this newsletter, we need your car photos. Please send us a photo of your car along with a description of any special features to: info@maximum-velocity.com

Please include your full name. If selected, we will include the photo and description in this newsletter.

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 car shown at:


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. Thanks.

Inventory Clearance Sale
We also are clearing inventory on several items including:
  • Light-weight (3.2 ounces and under) plain and slotted blocks,

  • Most of our SuperCar kits,

  • The ever-popular Wedge SE,

  • The special edition Funny Car Kit (only 19 left),

  • The Truck Kit, and the

  • Propeller Car Kit.

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

Height of Ballast Weight Vs. Performance - Part 2
By Randy Davis

Last season, I ran an experiment and published an article on the effect of the height of the ballast weight on performance (Volume 13, Issue 9 - Height of Ballast Weight Versus Performance).

That experiment showed that for a reasonable (9/16 inch) variance in the height of the ballast weight, there was no measurable effect on performance.

After the article was published, I received quite a bit of feedback claiming that the experiment was under ideal conditions so it could not be applied to real racing.

Truly, the test was done under as ideal conditions as possible, as I wanted to ensure that any variance in performance was due to the height of the weight and not some other factor. For example, outlaw (disk) wheels were used to minimize friction, and the track was very smooth.

So, to address the feedback I determined to run the test again with the following changes:
  1. BSA Wheels and Axles instead of Outlaw Wheels - these wheels have more track surface contact, and the wheel/axle fit is sloppy.

  2. Rougher track

Experiment Setup
The same car was used as in the original experiment (see Figures 1 and 2). Of course the wheels/axles were swapped out; Pro-Stock BSA Speed Wheels and BSA Speed Axles were used and lubed with Krytox 100 lube.


Figure 1 - Top of Test Car


Figure 2 - Bottom of Car with Weight and Spacers Inset

As a recap, the car has a 1-3/8 inch hole drilled completely through the car, and a medicine bottle cap with a 1-3/8 inch internal diameter is glued over the hole. The resulting cavity can hold a 3.25 ounce tungsten round (9/32 inch thick) and two hollow plastic spacers (same OD and thickness), and a thin plastic shim to prevent rattling. On the bottom of the car, the hole is covered with a removable plate (shown in Figure 2). Additional ballast weight was added to bring the car up to five ounces.

To add "roughness" to the track, strips of Post-it material was applied to the track. At each track joint, a strip was placed on both sides of the center guide rail. At the half-way point of each track section, a strip was placed on one side of the rail (alternating sides down the track). When the car raced, it made a pleasing clickety-clack train track sound.


Figure 3 - Post-it Strips on Track

The experiment started with the tungsten round at the bottom and the two spacers on the top. Three heats were run with this configuration. Then the plate was removed, the round placed between the spacers, and the plate replaced. After three heats with this configuration, the round was placed above the two spacers, and six heats were run. Then the configuration was changed back to the round in the middle for three heats, followed by the round at the bottom for the final three heats. Thus, six heats were run for each configuration.

Experimental Results
Other than the car being a little slower than in the original experiment, nothing else changed. The car was still very consistent, and performed the same regardless of the height of the weight.

  2.5308 Sec - Low COG Average
  2.5297 Sec - Middle COG Average
  2.5305 Sec - High COG Average
  0.0016 Sec - Standard Deviation

The greatest difference in average times (between the low and middle COG was 1.1 milliseconds which was less than the standard deviation of the data, so the difference is statistically insignificant.

Conclusion
Thus, the same conclusion can be drawn as in the original experiment: within reason (9/16 inch for this experiment) don't worry about the height of the COG. Certainly get the COG towards the back, keep your car aerodynamically sleek, and have fun designing your car. If you want to use a tungsten canopy, certainly don't be afraid to do so.



Humor

Darth Vader and Luke Skywalker were having a long drawn out duel on Christmas Eve. Lightsabers drawn and sparks flying Vader pinned Luke against a bulkhead and glared at him.

"I know what you're getting for Christmas, Luke," he said, "Ohhh, yes! I know!" Luke fought himself free and jumped to a higher platform just out of Vader's reach.

"How do you know!?" Luke yelled at him, "How do you know what I'm getting for Christmas!?"

Darth Vader snarled, "The force is strong with me... I felt your presents."



Product Showcase



Pinewood Derby Car Showcase

Arrow of Lightening - Scott & Derek Bobbitt

For his final foray in pinewood derby racing, my son Derek opted to showcase Scout Spirit and go for the "Lord Baden Powell" award for most Cub Spirit. His entry, the "Arrow of Lightening" succeeded. He won the Cub Spirit award and placed first out the 30 entries in the pack. At the district finals, five cars from each Pack were invited to participate. The "Arrow of Lightening" won every heat and placed second overall by just 0.007 seconds! Most importantly, though, his car won the District award for "Best-In-Show". He was one elated Webelos!

Triangulator - Gerald Scotting

After seeing the unusual triangular tungsten canopy I knew i wanted to design a car around it. The canopy made up most of the weight for the car, but due to the super slim design I was still too light. I ended up using a bunch of the 3/16" tungsten beads. The body was cut out as a side profile, then a rough top profile. All other shaping was done with either a round file or sandpaper, and lots of patience.

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!



Q&A

Two questions (actually three):
  1. When drilling axle holes is it 1/8 inch from the bottom, and then 1/16 inch higher for the raised wheel)?

  2. To set up alignment for rail-riding, do I first adjust in a straight line so the wheels do not move in or out, and then set the pull; or do I set the pull and then adjust the wheels in back to not move in or out? Also, is 4 inches over 8 feet the correct amount of drift?

Three Answers:
  1. Yes, I drill at 1/8 inch, and then 3/16 inch for the raised wheel. This is not hard and fast. You can go a little higher or lower. Just make sure to maintain the 3/8 inch ground clearance.

  2. First, you want to adjust the rear axles so that wheels stay on the axle heads regardless of the car direction (forward or backward). Then set the drift with the front dominant wheel.

  3. I recommend 5 inches over 8 feet.

I recently purchased a car kit. When I received it, it appears that the holes are drilled higher than the axle slots on the standard BSA blocks. I am concerned that the car will not clear the center guide rail. Do the drilled holes lower the car clearance too much?

When wheels/axles are mounted on a BSA block, the clearance is over 1/2 inch. The specification is 3/8 inch minimum, so there is over 1/8 inch of extra clearance.

When we drill axle holes, the axles are 1/16 inch higher on the block, which lowers the body by 1/16 inch. This reduces the clearance, but the clearance is still greater than 3/8 inch. You can temporarily mount the wheels/axles and measure this for yourself.

The only concern is to make sure that axle holes are allowed by your local rules. Some scout packs require you to use the original axle slots. Certainly check your local rules to make sure axle holes are allowed.

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 14 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

Copyright ©2014, 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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