Pine Wood Derby Car
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The pinewood derby is the wood car racing event of Scouts BSA. Pinewood derbies are often run by packs of the Cub Scouts program. With the help of adults, Scouts build their own unpowered, unmanned miniature cars from wood, usually from kits containing a block of pine wood, plastic wheels, and metal axles. With the popularity of the pinewood derby, other organizations have developed similar events. Pinewood derby is a registered trademark of the BSA, so most use different names. Each derby has slightly different rules for making and racing their cars. A small industry has developed to provide organizer equipment (e.g. tracks, timers, and scales) and awards (e.g. trophies and ribbons).
The first pinewood derby was held on May 15, 1953 (69 years ago) (1953-05-15) at the Scout House in Manhattan Beach, California by Cub Scout Pack 280C (the present Pack 713). The concept was created by the Pack's Cubmaster Don Murphy, and sponsored by the Management Club at North American Aviation.
Murphy's son was too young to participate in the popular Soap Box Derby races, so he came up with the idea of racing miniature wood cars. The cars had the same gravity-powered concept as the full-size Soap Box Derby cars, but were much smaller and easier to build.
The pinewood derby had a sensational first year. Murphy and the Management Club of North American Aviation sent out thousands of brochures to anyone who requested more information. The idea spread rapidly, and competitions were held across the country, mainly with recreation departments and nonprofit organizations including the Los Angeles County Department of Recreation. Of all that early enthusiasm, however, only the Boy Scouts of America made it part of an official program. The National Director of Cub Scouting Service, O. W. (Bud) Bennett, wrote Murphy: "We believe you have an excellent idea, and we are most anxious to make your material available to the Cub Scouts of America." Within the year, the Boy Scouts of America adopted the pinewood derby for use in all Cub Scout packs.
In 2003, Pack 713 celebrated the 50th Pinewood Derby along with Packs 287, 759, 275, and former Cub Scouts from the 1953 Pack 280c. A shoulder patch for the Western Los Angeles County Council that depicted a pinewood derby car and a message of honor to Murphy was released to celebrate the 50th anniversary of the event.
When using a kit sold through Boy Scouts of America (BSA), the Scout begins with a block of wood, four plastic wheels, and four nails for axles. The finished car must use all nine pieces, must not exceed a certain weight (usually five ounces (150 grams)), must not exceed a certain width (usually 2-3/4 inches (7 cm)) and length (usually 7 inches (17.8 cm)) and must fit on the track used by that particular Scout pack.
Blocks can be whittled with a hand knife, bandsaw, or a carving tool. Other than the previous basic design rules, the Cub Scout is able to carve and decorate the car as he or she chooses. Cars vary from unfinished blocks to whimsical objects, to accurate replicas of actual cars. Weights can be added to the final design to bring the car to the maximum allowable weight. A high-density metal weight, such as tungsten carbide which is not toxic like lead, reduces the volume of wood, which reduces air friction and increases speed. Axle friction can be reduced by polishing the nails and applying graphite as a lubricant.
The force accelerating a pinewood derby car is gravity; the opposing forces are friction and air drag. Therefore, car modifications are aimed at maximizing the potential energy in the car design and minimizing the air drag and the friction that occurs when the wheel spins on the axle, contacts the axle head or car body, or contacts the track guide rail. Friction due to air drag is a minor, although not insignificant, factor. The wheel tread can be sanded or turned on a lathe and the inner surface of the hub can be tapered to minimize the contact area between the hub and body. Polishing the wheel, especially the inner hub, with a plastic polish can also reduce friction. Often one front wheel is raised slightly so that it does not contact the track and add to the rolling resistance. Axles are filed or turned on a lathe to remove the burr and crimp marks and polished smooth. More extensive modifications involve tapering the axle head and cutting a notch to minimize the wheel-to-axle contact area. Packs can establish additional rules for what, if any, modifications are allowed. In some areas, no changes can be made to the axles or wheels.
A second consideration is the rotational energy stored in the wheels. The pinewood derby car converts gravitational potential energy into translational kinetic energy (speed) plus rotational energy. Heavier wheels have a greater moment of inertia and their spinning takes away energy that would otherwise contribute to the speed of the car. A standard wheel has a mass of 2.6 g, but this can be reduced to as little as 1 g by removing material from the inside of the wheel. A raised wheel can reduce the rotational energy up to one-quarter, but this advantage is less with a bumpy track.
A proper lubricant, typically graphite powder, is essential. Wheel alignment is important both to minimize wheel contact with the axle head and body as well as to limit the contact between the wheels and guide rail as the car travels down the track. There are 32 friction causing surfaces on a pinewood derby car. These include the surfaces of all four wheels which touch either the axle, the body or the track and the surfaces of all four axles which touch the wheel. Neglecting to polish and lubricate any of these 32 surfaces will result in degraded performance. The center of mass of a typical car is low and slightly ahead of the rear axle, which helps the car track straight as well as providing a slight advantage due to the additional gravitational potential energy.
The pinewood derby was selected as part of "America's 100 Best" in 2006 as "a celebrated rite of spring" by Reader's Digest. The event has also been parodied by South Park in the episode "Pinewood Derby" and in the film Down and Derby.
Precision tuned wheels give your derby car perfect balance to reach maximum speed. BSA Lightly Lathed or Ultra-Lite Wheels with our PRO exclusive graphite-coating minimizes friction to maximize speed. Awana racers can use our lathed Awana® Grand Prix speed wheels. Compare speeds with track tests
Pinewood Pro is the exclusive seller of The Story of the Pinewood Derby, written by the inventor of pinewood derby racing, Don Murphy. We are also the proud sponsor of the national pinewood derby museum Hall of Fame. As an engineer, I designed many unique products like our patented PRO Tools, graphite-coated axles and wheels.
When your car wheel rubs against the axle head it can cause the wheel to wobble because the corner of the axle head is not a perfect 90 degrees. Cutting a groove directly under the axle head removes this source of wheel wobble. Cutting this groove is difficult to do by hand, but it can be done with an axle file. Our grooved Speed Axles and Pro Super Speed axles have this groove, exclusive to Pinewood Pro, cut directly under the axle head.
Avoid designs with a pointed nose. A pointed nose will make it difficult for your Pinewood Derby car to rest on the pin at the starting gate. It may also cause your Pinewood Derby car to get bumped around when the pin drops, and it can create problems for electronic timing systems.
1. Bake the Block: Start with your block of wood, and before you do anything else, bake it in the oven at 250 degrees for around two hours to remove moisture and make it lighter. This will allow you to place more weight to the rear of the Pinewood Derby car where you actually want it.
Pinewood derby is a great way to teach cubs about physics. Basically the car body represents stored energy. One trick to speeding up a car is to remove mass from the wheels so that less energy is required to start and keep the wheels turning. Less mass in the wheels also allows more weight to be added to the body.
Most Pinewood Derby cars will fishtail to some degree as they roll down the track. Fishtailing slows the car down by increasing friction when the wheels touch the center guide rail. You can reduce fishtailing by sanding the front of the car so that the wheels on the front are slightly closer together. Then as the car goes down the track, only the front wheels will touch the center guide rail.
If you know that you are going to be up against some very fast pinewood cars, focus on one of the workmanship or design prizes. Building a good looking car with a creative design can be more fun than making a fast car.
I wanted to thank you for your prompt service, great products and winning tips. My son Joshua, a first grader and a first time racer, placed second last night in his Cub Scout Pack's pinewood derby race. He was so proud when his name was called and he received his trophy. I placed my order online, received your products in just a few days and then scoured your website for tips on how Joshua and I could build a fast car. You've got it down! Thanks again, Rob and Joshua
In order to build a successful pinewood derby car, you first need to understand the basics of how these cars move. Essentially, there are three forces at work during every competition. Gravity pulls the cars down the sloped track, gaining momentum. This momentum is used to cross the long, flat section on the way to the finish line. The force working against the car is friction, which is mainly manifesting in two spots: wherever two or more car parts touch each other, like the wheels and axles, and air resistance as the car races down the track.
The highest density weights available for pinewood derby use is tungsten and lead. Tungsten is the most popular weight used because in addition to its high density, tungsten is also non-toxic and environmentally friendly. While lead has comparable density, it is dangerous to handle, and should only be used by adults. 781b155fdc