Pinewood Derby Car Showcase – March 27, 2015

Chima Eagle – Tony Jochman


This is the car that my son and I built for the PineCar Derby last year. He wanted a car that looked like the Lego Chima eagle tribes motorcycle set he had gotten for his birthday. Well this was definitely a challenge, but we did end up tracing parts from his Lego set which helped a lot. After he got done painting, even I was amazed at how it turned out. He got 3rd place in speed (and 1st in craft) at the train level, then 4th place for speed at the district level. Now he is ready to go for gold this year (pictures to come). Thank You Maximum Velocity for all your help.

Awana Express – Ken Temple


I have a couple of cars I would like to show-off. These are cars that I built two years in a row. I wanted to have my wife and kids make a set of four train cars as a family project, but sadly no one wanted to be the coal car. One is a locomotive, the other is a caboose. The center wheels on the locomotive are stationary, narrowed, and flattened so there is no possibility of contact. The smoke stack is a .44 Mag hand gun casing with a bell on top. For special effects, I put some dry ice in the stack after the race. The hand rails and smoke stack on the caboose are brass tubing that I bent and soldered. The steps are zinc weights painted black. And the wheels are actually sanded down to have an inner lip like a real train wheel and painted with a silver marker. Thank you again for all your help over the years.

BSA Big Rig – Eric Werner

First up is the simplest, the 2010 BSA Big Rig. I was given this as a gift a few years ago, and finally got around to putting it together. It was pretty easy to put together, and served it’s function well. We used the cab as our opening “pace car”, since the track our pack uses couldn’t accommodate the trailer and cab at the same time. Plus, the truck served another function, which I will reveal in a moment…

From Pinewood Derby Times Volume 14, Issue 13

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(C)2015, Maximum Velocity, Inc. All rights reserved.

Maximum Velocity Pinewood Derby Car Plans and Supplies

Pinewood Derby Car Showcase – March 20, 2015

Flex Car – Bret Wortman


My son’s Flex Car came away with the Grand Champion’s trophy (44 cars raced total). The weight box is supposed to be a tent. We didn’t have enough time to model one properly, but this came pretty close.

Swiss Army Knife – Dave & Cole Oshman


My son, Cole, and I are particularly proud of our car this year. The original intent was to be in the running for the Most Scout Spirit trophy but my son wanted it to be fast as well. Since he’s a Webelos, he did all of the axle and wheel work, along with all of the paint (I masked for the red coat). The design was my idea, and the corkscrew rotates out. I’ve been building cars for 9 years now and don’t recall seeing a design like this.

Based on all of the help I’ve gotten from you through the years, the car ended up winning first place in the Pack for speed. They’ll give out the design trophies next week at the Blue and Gold Banquet. Hoping that Cole will get one more for his shelf.

Mouse Trap Car – Mike Henkelman


This car was built to compete in the mouse trap division at our pinewood derby event. The car is dimensionally and weight compliant with pinewood derby specifications.

Using a rubber band to attach the mouse trap to the rear axle, the car will accelerate for 15 to 20 ft.

From Pinewood Derby Times Volume 14, Issue 12

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Maximum Velocity Pinewood Derby Car Plans and Supplies

Using a Scale Plastic Model for a Pinewood Derby Car

In our most recent issue of the Pinewood Derby Times, we included an article by Andy Holzer entitled “Using a Scale Plastic Model for a Pinewood Derby Car”. The article includes a step by step photo pictorial of how to mount a plastic model body on a pinewood derby frame. You can view the full article Here


Model Kit


Completed Car

From Pinewood Derby Times Volume 14, Issue 12

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(C)2015, Maximum Velocity, Inc. All rights reserved.

Maximum Velocity Pinewood Derby Car Plans and Supplies

Shifting the Pinewood Derby Wheelbase

By Randy Davis

The standard pinewood derby kit from BSA (as well as PineCar and Maximum Velocity), has an offset wheelbase, with one slot approximately 1-3/4 inches from the end of the block, and the other slot approximately 1 inch from the end of the block. The 1 inch slot is generally used as the rear axle, as this places the rear axle as far up the hill as possible, thus allowing the center of gravity (COG) of the car to be as far up the hill as possible.(1)

Some races do not place restrictions on the wheel base, thus allowing the builder to extend the wheelbase by moving the rear axle back and the front axle forward. Other races place restrictions on both the location and position of the wheelbase, thus preventing any adjustment to the wheelbase.

But some races restrict the distance between the front and rear axles, but do not place a restriction on the location of the front and rear axles. In this case, the wheel base can be shifted to potentially gain an advantage (see Figure 1). But does this really provide an advantage, and if so, how much advantage is attained? Let’s find out.


Figure 1 – Shifted wheelbase

METHODS TO SHIFT THE WHEELBASE

There are several ways to shift the wheelbase:

– If axle holes are allowed in your race (as opposed to requiring the use of axle slots), then new axle holes can be drilled with a Pro-Body Tool, Pro-Body Jig, or with a drill press.

– If axle slots are required, then new slots can be cut with a Pro- Body Slotter.

– If the original slots must be used, then a piece of the block can be cut off the back and glued to the front. (See Figure 2).


Figure 2 – Shifting the Wheelbase While Retaining the Original Slots

EXPERIMENT SETUP
In our experiment, we want to avoid changing any factor that would affect the performance of the car, other than the shifted wheelbase. So we will leave the original wheelbase intact, and effect the shift by moving a part from the back of the car to the front of the car (See Figure 3).



Figure 3 – Test Car
(Note the styrene piece at the back of the car in the first photo, and the front of the car in the second photo)

The body of the test car was shortened by 1/4 inch, and then a thin slot was cut crosswise on both the front and back of the car. A piece of styrene was cut such that when installed into one of the slots, the car measures seven inches long. By moving the styrene between the front and back of the car, the wheelbase is shifted by 1/4 inch without changing any other factor on the car.(2)

The car is equipped with polished speed axles and Pro-Stock Speed Wheels, and is lubed with Krytox 100. The car has a raised front left wheel, and is aligned to rail-ride. A 3.5 ounce tungsten canopy provides the majority of the weight, with a small amount of tungsten putty (in holes behind the rear axle) to bring the total weight up to five ounces. The COG of the car is 7/8 inch in front of the rear axles.

Five heats were run with the styrene piece at the back of the car (standard wheelbase), then ten heats were run with the styrene piece at the front of the car (shifted wheelbase). Finally, five heats were run with the styrene piece at the back to even out the heats to ten in each position.

RESULTS
Standard Wheelbase Average – 2.542 sec; Std. Deviation – .0016
Shifted Wheelbase Average – 2.539 sec; Std. Deviation – .0008

The data shows an improvement in time with the shifted wheelbase of .003 seconds. This is more than the standard deviation, so the difference is statistically significant.

CONCLUSION
Going into the experiment I expected an improvement from the shifted wheelbase, but I expected the improvement to be more than 3 ms. It is possible that the improvement due to the wheelbase shift would be larger if other factors could be minimized. For example, if disk (outlaw-type) wheels were used, the improvement due to the shifted wheelbase may be amplified.(3)

(1) More information on modifying the wheelbase can be found in Volume 10, Issue 13.

(2) The main issue with an experiment of this kind is that moving material from the back to the front changes the COG of the car. The advantage to the styrene piece is that the change is negligible since the styrene weighs less than 1/10th of a gram.

(3) I’ve added this to my list of future experiments.

From Pinewood Derby Times Volume 14, Issue 11

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(C)2015, Maximum Velocity, Inc. All rights reserved.

Maximum Velocity Pinewood Derby Car Plans and Supplies