Pinewood Derby Car Showcase – August 28, 2012


Runaway House & Yellow Fireball – Matt & Will Osbourne

These are my son’s cars from their recent pack pinewood derby. On the left is Matt Osbourne’s ‘Runaway House’. He’s a Webelo 1 and this is the fourth car he’s raced. He finished first in rank and had the 8th fastest time in the pack (50 cars in competition). On the right is Will Osbourne’s ‘Yellow Fireball’. He’s a Tiger and this is his first official car. He finished first in rank and had the 6th fastest time in the pack. He’ll be going on to represent his pack at the district races since he was the fastest Tiger. I’ve been reading the newsletter for almost two years and picking up tips. Both racers are three wheelers with a good rear center of gravity and the boys spent a lot of time in front of the drill press polishing the axles until they gleamed. I made a test track this year based upon instructions from a prior year’s newsletter and we had the cars well aligned before test and tune night.

‘Vette – Jay & Jay-Jay Bailey

I recently ordered a DerbyDome for my son Jay-Jay’s pinewood derby race car. He is with the RA’s (which is a church run scouting organization). On March 12, 2005 the RA’s held a regional event in Wilson, North Carolina with over 200 participants from all over the eastern part of North Carolina. The car that we built together won a 1st Place ribbon for most unique design and a trophy for best in show. Jay-Jay turned 7 years old that day, and needless to say, he was elated to win a trophy and a blue ribbon on his birthday! Your DerbyDome will protect and display his winning car for years to come and we thank you for offering such a wonderful product.

WoodBadge Beaver’s ’32 Chevy – David Bivins

(I broke my ‘one car’ rule for this submission, as the three cars make a nice set.) This year’s car is 5 ounces of pinewood taken from three car kits and plastic pieces from a 1932 Chevy model. It is driven by a WoodBadge Beaver. It was a little slow, but looked good getting there! Last year’s “Beaver’s Ford Cobra” and 2003’s “Beaver on a Sled” are on display at Birmingham’s Scout Shop.

From Pinewood Derby Times Volume 5, Issue 1

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(C)2012, Maximum Velocity, Inc. All rights reserved.

Maximum Velocity Pinewood Derby Car Plans and Supplies

Designing a Car From Scratch

I have been asked several times, “How do you come up with your designs?” The obvious answer is ‘imagination’, but really I am not the most imaginative person around. A better answer is that I think about car designs on a regular basis. I am also a ‘doodler’. When I have a piece of paper and a pencil I tend to sketch out car profiles. I have found if I do this enough, I eventually come up with something useful.

Of course there is more to designing a car than just sketching out a profile. The car must also meet various criteria, some imposed by the rules, and others that are needed for good performance. In this article I will share with you some of the things I have learned about car design, which I trust you will find useful when it comes time to design your own car.


When the derby race date is approaching and time is at a premium, it is tempting to draw a few lines and start cutting. But before you do that, ask yourself a few questions:

1. Weight: Depending on how much wood you remove, you will need to add between 2.5 to 3.5 ounces of weight. Too often car builders don’t consider the need to add weight until after the car is shaped and painted. At that time it is difficult to add any weight, much less add enough weight at the best location.

So, when designing a car, make sure to consider the following:

– Weight Amount: Make an estimate as to how much weight must be added to achieve maximum weight. The amount will depend on the amount of wood that is removed and the density of the wood. When I design a car, I use previous models as a guideline, and I build several prototypes until I get it right. If desired and time permits, you can build prototypes as well. But if not, the weight uncertainty can be dealt with (see ‘Weight Placement’ below).

– Weight Type: Determine the type of weight (shape and material). The density of the weight makes a huge difference as to how much space will be required to hold the weight (See Figure 1 which shows the relative density of three popular weight types). Clearly much more space must be reserved for zinc weight than for tungsten weight.

Figure 1 – Density Comparison of Popular Weight Types

– Weight Placement: For best performance on the most popular track lengths (32 to 45 feet) the center of gravity (the front-to-back balance point of the completed car) should be located between 3/4 and 1 inch in front of the rear axle. To achieve this balance point, a ‘rule of thumb’ is to place 1/3 of the added weight behind the rear axle, 1/3 on top of or just in front of the rear axle, and the final 1/3 about 1-1/2 inches in front of the rear axle.

I suggest embedding all of the weight in the car, as opposed to having it hang below the bottom of the car. I oftentimes embed about 2/3 of the weight in the car such that it is not visible. This is done with holes, or with pockets that are covered with wood filler. The remaining 1/3 of the weight is embedded into the bottom, so that it
can be adjusted at the weigh-in. If the amount of weight needed is uncertain or if you don’t have access to a scale, you can create holes/pockets for the final 1/3 of the weight, but wait until the weigh-in to install it.

2. Axle Location: For standard wheelbase cars (such as BSA kits), best performance is generally achieved by using the axle slot closest to the end of the block as the rear axle. This is just the opposite of the car pictured on the kit box.

3. Wheel Base: If allowed by the local rules, extend the wheel base to the maximum length. Long wheelbase cars go straighter, are more stable, and allow the center of gravity to be located further towards the rear of the car. For the opposite reasons do not shorten the wheelbase.

4. Aerodynamics: The fastest cars tend to be low-slung and aerodynamic. While the amount of effect from wind drag on a derby car is a secondary speed factor, it is prudent to recognize the presence of wind drag and avoid design features that would increase this effect. Thus, use a basically aerodynamic design, and avoid the use of accessories that could catch air such as sails, streamers, etc. Also, rounding off the leading and trailing edges of the car serves to reduce aerodynamic drag.

5. Symmetry: An important design factor that affects the speed of a car is left-to-right symmetry. By this I mean that the left side of the car should be a mirror image of the right side of the car (see Figure 2 for an example of a non-symmetrical car). Why is symmetry important? Because a car that is not symmetrical will be heavier on one side, and will tend to ‘steer’ to that side. Thus, after the wheels/axles are adjusted to make the car roll straight, there will be an increase in friction as the car tries to turn, but the wheels/axles prevent the turn. This extra friction will slow the car down.

Figure 2 – Non-Symmetrical Car

6. Blunt Point: Avoid designs that have a sharply pointed front end. There are two reasons for this caution. The first is that most tracks have round rods that hold the cars at the starting line. A car with a sharp point will tend to slip off of the rod, which could cause the car to start at an angle. The second reason for avoiding a sharp point is that the point may not trigger the finish line sensor until the car has progressed a little bit past the finish line. This could be important in a close race. So, make sure that the nose of the car is blunt so that it will sit properly at the starting line and properly trip the finish line.


Now that you know where the weight will go, get some graph paper. Then in full scale, draw the side profile of the car, then the top view, the bottom view, and the rear view of the car. Note the location of weight pockets and holes. If you don’t like what you have drawn, just do it again. It’s much cheaper and easier to throw away ideas on paper than to throw away a partially worked block of wood!


Once you have decided on a design, determine whether the design can be cut directly out of one block, or if it would more easily be built from two or more pieces of wood. For example, the faring on the back of the car in Figure 3 is a separate piece of wood glued to the body. In Figure 4, the wings, the side air intakes, and the faring are separate pieces of wood.

Figure 3 – Car with Faring

Figure 4 – Car with Multiple Added Pieces


Finally, decide if you will add on any decorative items such as engines, exhaust pipes, etc. If so, then mark any holes/pockets required for the item. In Figure 5, the roll cage is constructed from aluminum rod. To mount the rods, holes were drilled in the top of the body. In Figure 6, shallow pockets were made to accommodate the pipes and engine. These pockets ensure that the items are firmly glued to the car.

Figure 5 – Roll Cage

Figure 6 – Multiple Car Parts


Designing a car on paper can be fun, and will give multiple benefits:

1. Save you time by minimizing rework.

2. Achieve better performance by ensuring that weight is properly accommodated.

3. Simplify construction by identifying holes/pockets that need to be created, and helping you identify multiple parts.

Okay, let the drawing begin!

From Pinewood Derby Times Volume 5, Issue 1

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(C)2012, Maximum Velocity, Inc. All rights reserved.

Maximum Velocity Pinewood Derby Car Plans and Supplies

Wheel Work Speed Tip

I use the Pro-Wheel Mandrel to remove material from the inner tread, but

also for removal of material from the inside center of the wheel. I use a flat or chisel blade on an Exacto knife and very gently and slowly apply it to the surface from which I am removing material. I mount my mandrel in a Porter-Cable cordless drill mounted upside down in a vise. I place a tie wrap around the trigger. The Porter-Cable drill has a battery that slides on rather than being inserted. With the drill upside down and a tie wrap around the trigger I slide my battery slightly away from the contacts to turn the drill off and slide it forward to engage the contacts to turn it on. With this set up and the Pro-Wheel Mandrel I have a great wheel lathe. I have been able to remove approximately 15-20 percent of the wheel weight, which is a big advantage. Caution – If you smell burning plastic you are pressing on the wheel too hard.

Ren Ramsey

From Pinewood Derby Times Volume 4, Issue 15

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(C)2012, Maximum Velocity, Inc. All rights reserved.

Maximum Velocity Pinewood Derby Car Plans and Supplies