PINEWOOD DERBY TIMES
Volume 16, Issue 5
November 30, 2016
In this Edition
– Editor’s Notes
– Feature Article – Open Weight Pockets – Do They Affect Speed?
– Product Showcase – Holiday Shopping – 10% Off
– Pinewood Derby Memory – Star Ship Tribute
– Pinewood Derby Car Showcase
Maximum Velocity is introducing a new product just in time for the prime racing season:
– Pre-Cut Bulk MV Car Kits – We made a special run of pre-shaped bulk car kits. The kits are shaped and sanded, and ready for final sanding and painting. Each bulk pack contains three each of four shaped car bodies, wheels, axles, instructions and baggies. You can find them Here.
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.
Call for Photos
Help, we are virtually out of photos for the pinewood derby car showcase. Please send us a photo of your car along with a description of any special features to:
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 640×480, maximum size of 1280 x 960). Please shoot photos from the front left of the car, similar to the orientation of car shown at:
Make sure the photo is not blurry. If your photos are blurry, try holding 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. Don’t forget to include your name, the name of the car (if it has one), and a brief write up on any design features, inspiration for the design, and how the car performed at the race. Thanks.
nventory Clearance Sale
We are clearing inventory on several items including:
– Discount slotted blocks
– Formula One car kit
– Wheel Flares and Paint Stencils
– Raingutter Regatta Decals
We don’t have many left, so don’t delay. You can find these items Here.
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.
Open Weight Pockets – Do They Affect Speed?
By Randy Davis
A common method of adding weight to a car is to drill holes or create pockets in the bottom of the car, and then glue weight into the pockets. Generally, not all of the pocket or hole space is used, so there are open cavities in the bottom of the car.
Some people advocate filling in open cavities, thus creating a smooth surface on the bottom of the car. The belief is that open cavities affect the aerodynamics of the car, leading to slower speeds.
But is this true? If it is true, then certainly the effort required to fill the cavities is justified. On the other hand, filling in cavities creates weighing issues as the weight of the filler must be taken into account. So if open cavities do not affect speed, then the effort is wasted (other than a possible improvement in the looks of the car).
Let’s see if we can answer this question.
To test the effect of open cavities on performance, a test car was created with a large amount of open cavities. The car was weighted to 5.035 ounces, and was equipped with the following features:
– Balance point at 11/16 inch in front of the rear axle,
– RS wheels with nickel speed axles, (1)
– Krytox 100 lube
– Alignment set to rail ride
– 32 foot aluminum track
Figure 1 Test Car
Figure 2 Test Car Bottom – Without Tape
A strip of clear packing tape cut to the proper width was placed over the entire bottom of the car, thus creating a smooth bottom with no cavities. The car was then re-weighed – 5.05 ounces.
Five heats were run with the smooth bottom. The tape was then removed, and tungsten putty (.015 ounces) was added at the center of the car to account for the tape weight. Then five heats were run with the open cavities.
The runs averaged and the standard deviation calculated:
Smooth Bottom – Average – 2.466 seconds, .0012 standard deviation
Open Cavities – Average – 2.466 seconds, .0013 standard deviation
Obviously, open cavities do not affect performance. My belief is that since the peak speed of a pinewood derby car is less than 20 MPH on a standard track, the aerodynamics of a car are only affected by:
– changes in the frontal cross-section of the car,(2)
– creating a smoother profile, and improving air flow with fenders,(3)
– elimination of sails, streamers or other air catching accessories.
So, unless you are an aesthetic purist, I wouldn’t bother covering open pockets or holes in the bottom of the car.
(1) I chose to use disk wheels instead of full width wheels to
minimize the overall aerodynamic profile of the car, so that if open
pockets did affect speed the effect would tend to be amplified.
(2) Proven in a test done in 2004, which will be revisited in a future
article this season.
(3) Proven in a test done in 2013. Click Here for the article.
Want To Go Out?
One Saturday, as Mom was finishing the dinner dishes, my father stepped up behind her. “Would you like to go out, girl?” he asked.
Not even turning around, my mother quickly replied, “Oh, yes, I’d love to!”
They had a wonderful evening, and it wasn’t until the end of the evening that Dad finally confessed that his question had actually been directed to the family dog, laying near Mom’s feet on the kitchen floor.
Holiday Shopping – 10% Off
Here at Maximum Velocity we wish you and your family a great holiday season. To help with gift giving, through December 13, 2016, you can get 10% off your entire order.
Pinewood Derby Car Showcase
Today’s cars are from Jeff Bartel.
This was Nickolas’ second car and his fastest (2nd in the Pack). It was based on two or three designs he found online and combined.
This was Nickolas’ first car as a Webelos. He wanted to go for scout spirit (which he won) and speed (which didn’t work out quite as well due to some alignment issues). He was proud of using the scroll saw to put his initials into the front of the car.
This was Nickolas’ final car. He was done with trying for speed and was focused on the design award, which he won. He carved the shuttle out of two pieces of balsa wood, and the external fuel tank and SRBs were dowels that he sanded down (and added toothpicks to the former and wire nuts as the engines to the latter). The shuttle sits on a skateboard of the original PWD kit.
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 description of any special features to:
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 640×480, 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
Star Ship Tribute
My wife Jennifer accepted the call to become the children’s pastor at a church in Kansas. One of the first things I asked when I got to the church was “What would you most want out of my time here?”
Knowing that I had experience with the pinewood derby, the youth pastor Philip spoke up and said (among other things): “The District Director of Kansas has never lost a Ranger Derby Race in ten years.”
I knew that we could be competitive with the ten-time champ but, I did not make any promises.
About a month later the Ranger Derby building started, While the Royal Rangers made dragsters, speeders, racers and other high performance racing machines, Pastor Philip wanted to make a Starship Enterprise from the movie Star Trek. I told Pastor Philip that his car looked cool and it could also win – if we ran it backwards. So, Pastor Philip began building his car. He was at the primer step, when he had to have tonsillectomy surgery.
During the surgery something happened and Pastor Philip died, leaving his unfinished Ranger Derby car. The Royal Rangers and the youth group were stunned, and wondered how we could show honor to Pastor Philip. We all decided to finish Pastor Philips car and race it in his honor.
The Royal Rangers worked hard on their cars, and on Pastor Philip’s car. They were able to run two test races against the reigning ten-time champ with their own cars. They almost won. But we had one trick up our sleeve. For the state race we had finished Pastor Philip’s car with a fresh paint job. We also ordered new wheels and lube from Maximum Velocity.
Race day arrived! All of our cars passed inspection with flying colors, even Pastor Philip’s with a split nose that went around the start pin. So the race was on, we had two Rangers that got third and fourth in the state, and all that was left was the leader’s class with Pastor Philip’s car. As expected with a split nose the race officials allowed us to put tape across the nose so the car would stay behind the pin on the start gate. The first race we lost by an inch, but the next three we won by a inch or more! We knew all of the times would be close, but would Pastor Philip’s car win?
The District Director explained what had happened to Pastor Philip, and that we finished and raced the car for him. He then said, “First Place, winning by three thousandths of a second: Pastor Philip!!!!”
That Sunday, I presented the car and medal to Pastor Philip’s Mom and Dad. Most everyone was at least a little misty eyed. The Royal Rangers wanted in our own way to give a little honor to Pastor Philip to remember what a good man he was.
Do you Remember?
If you have a pinewood derby story that is funny, unusual, sad, heart-warming, etc., please send it to me in an e-mail. Don’t worry about literary polish. We will edit as needed before publishing.
If your story is used, you will receive a $10 coupon in May of 2017.
Q: This year, we’ve been trying to utilize more Physics; we’ve heard the competition is going to be tougher this year. Last year we didn’t worry about putting the weight in the rear, aerodynamics, or anything; we just polished the axles and did the work on the wheels and we won. For this year we found out that one of our competition is utilizing aftermarket BSA speed wheels and speed axles, and he’s using a type of “Quick Start” tactic by putting a “V” cut in the front of the car and using the paperclip trick to leverage the top of the starting dowel. Supposedly when the lever is pulled, his car may get a head start to help him along. What do you think about this quick start trick?
A: Don’t worry about this. On modern tracks, the quick start trick has no benefit, and may be detrimental if the paper clip gets bent or does not trip the finish line sensor. For more information, take a look at the article in This Newsletter.
Q: I’ve always been told that graphite breaks down and wears out after about 10 races. Yet, on your website, there was a test run that was done with 20 races and the results seem consistent. What’s the truth behind graphite usage and how soon it wears out before needing to be reapplied?
A: If you do a thorough lube job, then you should get 20 heats. That is why the instructions say to spend the time adding, spinning, adding, spinning, etc. I recommend five minutes per wheel for this process, always ending with spinning. What you are doing is building up multiple coatings of graphite on the wheel bore. If you get enough layers, it will last the 20 heats, and you will have a very fast car. If you don’t get enough coatings, then it will wear out prematurely. If you don’t spin after the last addition of graphite, then the first few heats will be slower as the last added graphite must be worked in.
Do you have a pinewood derby-related question? If so, e-mail us your question.
We answer all questions by e-mail, but not every question will appear in the Q&A section of the newsletter.
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 16 are posted on our web site Here.
We welcome your contributions. If you would like to contribute an article, a web site review, a speed tip, or a pinewood derby memory, please e-mail us.
The Pinewood Derby Times is a free e-newsletter focused on pinewood derby racing. It is published biweekly from October through March.
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Randy Davis, Editor, Pinewood Derby Times
E-Mail: [email protected]
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