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Pinewood Derby: Difference between revisions
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'''Pinewood derby''' is a racing event for unpowered, unmanned miniature cars. Pinewood derbies are often run by chapters (packs) of the [[Cub Scouts]] program of [[Boy Scouts of America]]. With the help of adults, Scouts build their own 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, and a small industry has developed to provide organizer equipment (e.g. tracks, timers, and scales) and awards (e.g. trophies and ribbons). Similar Cub Scouting events include the [[Raingutter Regatta]] (a race for miniature boats) and the [[Space Derby]] (a race for rubber band-driven propeller shuttles). | '''Pinewood derby''' is a racing event for unpowered, unmanned miniature cars. Pinewood derbies are often run by chapters (packs) of the [[Cub Scouts]] program of [[Boy Scouts of America]]. With the help of adults, Scouts build their own 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, and a small industry has developed to provide organizer equipment (e.g. tracks, timers, and scales) and awards (e.g. trophies and ribbons). Similar Cub Scouting events include the [[Raingutter Regatta]] (a race for miniature boats) and the [[Space Derby]] (a race for rubber band-driven propeller shuttles). | ||
* '''[[STEAM]] - Science, Technology, Engineering, Arts and Mathematics''' | |||
== History == | == History == | ||
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In its October 1954 issue, ''[[Boys' Life]]'' publicized the event and offered plans for the track and a car, which featured "four wheels, four nails, and three blocks of wood."<ref name="Wendell" /> | In its October 1954 issue, ''[[Boys' Life]]'' publicized the event and offered plans for the track and a car, which featured "four wheels, four nails, and three blocks of wood."<ref name="Wendell" /> | ||
==Construction== | |||
[[File:Pinewood.jpg|thumb|left|Official car kit]] | |||
When using a kit sold through Boy Scouts of America (BSA), the Scout begins a block of wood, four [[plastic]] wheels, and four [[nail (fastener)|nails]] for axels. The finished car must use all nine pieces, must not exceed a certain weight (usually five ounces (150 grams)),<ref name="bsa_buildit">{{cite web |url=http://www.pinewoodderby.org/#/one/buildit |title=Pinewood Derby |publisher=Boy Scouts of America |accessdate=October 28, 2014}}</ref> must not exceed a certain width (usually 2-3/4 inches (7 cm))<ref name="bsa_buildit"/> and length (usually 7 inches (17.8 cm))<ref name="bsa_buildit"/> and must fit on the track used by that particular Scout pack. | |||
Blocks can be [[whittling|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 chooses. Cars vary from unfinished blocks to whimsical objects, to accurate replicas of actual cars. Weights (e.g. coins or other bits of metal) are added to the final design to bring the car to the maximum allowable weight, to improve speed. Axel friction can be reduced by polishing the nails and applying graphite as a lubricant. | |||
==Competition== | |||
The track usually has two to eight lanes and slopes down to the ground, since the cars are powered by [[gravity]]. Tracks may be owned by the pack or rented. The race is run in heats, giving every car the chance to run on each lane. The racers can be grouped with others from the same rank (Tiger Cubs, Wolf Cubs, Bear Cubs, etc.), or can compete against the pack as a whole.<ref>{{cite web |title= Tips to get you started building a Pinewood Derby car track |publisher= ABC Pinewood Car |url= http://www.abc-pinewood-derby.com/pinewood-derby-track.php |accessdate= February 11, 2013}}</ref> | |||
[[File:Track Pinewood Derby.jpg|thumb|upright|Car track]] | |||
First, second, and third-place winners usually receive ribbons, medals, or [[trophy|trophies]]. Some packs also award on the basis of car design or styling. The first place race winners get to advance to the district level, then each of the district-wide race winners get to race each other from across the entire council.{{citation needed|date=March 2013}} | |||
==Car modifications== | |||
[[File:One gram compare.jpg|thumb|left|Stock wheels (left) and modified (one gram) wheels (right)]] | |||
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.<ref name=cowley>{{cite journal |last= Cowley |first= E. Roger |title= Pinewood Derby Physics |journal= The Physics Teacher |volume= 27 |issue= 8 |pages= 610–612 |date=November 1989 |doi= 10.1119/1.2342889|bibcode= 1989PhTea..27..610C }}</ref> 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.<ref name=cowley/> | |||
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.<ref name=cowley/> | |||
Another consideration is the track itself. A track that is mostly sloping, with little flat at the end, can allow cars with minimal mass in their wheels to shine. However, a track with a steep slope and then a long flat section can penalize such cars due to the quick loss of energy they experience once they have reached the bottom, when all potential energy has been transferred to kinetic and rotational energy. Such cars will take a lead on the downslope, but may be passed by cars with more energy "stored" away as rotational energy on the flat.<ref name=cowley/> | |||
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.<ref>{{cite web |url= https://www.maximum-velocity.com/free-speed-tips/ |title= Five Keys to Pine Derby Performance |work= Maximum Velocity |accessdate= September 26, 2008}}</ref> | |||
== Event Planning == | |||
The Pinewood Derby Pack Meeting, is one of the most extraordinary events of the program year for most Cub Scout packs. It incorporates all five elements of [[STEAM]] (Science, Technology, Engineering, Arts and Mathematics). In addition to the race itself, the pinewood derby features the following activities: | |||
* '''Race-car Weigh-in''' - Most races limit the car to just 5.0 oz. A race official accepts the car at the beginning and verifies that it meets all racing rules (ie weight, size, material, no mechanical devices, etc). After weigh-in, contestants cannot touch or modify their cars (except for emergency repairs.) | |||
* '''Judging Contest''' - many entries are submitted for their artistic effort. "It may not be the fastest, but it sure looks very sharp." This is an opportunity to create a unique participation award certificate for every single participant of the event. | |||
* '''Decorations''' - Many derby events featuring elaborate racing decor gathered over the years. | |||
* '''Siblings Race''' - In the spirit of creating a family friendly event - although the primary racing and awards are limited to registered cub scouts of the pack, most packs hold siblings and parents races for the other family members to create, race and display cars of their engineering, artistic persuasion. | |||
==Legacy== | |||
The pinewood derby was selected as part of "America's 100 Best" in 2006 as "a celebrated rite of spring" by ''[[Reader's Digest]]''.<ref>{{cite web |year= 2006 |url= http://www.rd.com/cub-scouts-pinewood-derby-race/article.html |title= Best Mother-Son Finish |work= Reader's Digest |accessdate= February 29, 2008}}</ref> The event has also been parodied by ''South Park'' in the episode "[[Pinewood Derby (South Park)|Pinewood Derby]]" and in the film ''[[Down and Derby]]''.<ref name="BSA Museum"/> | |||
== References == | == References == | ||
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[[Category: Cub Scouts]] | [[Category: Cub Scouts]] | ||
[[Category: Boy Scouts of America]] | [[Category: Boy Scouts of America]] | ||
[[Category: STEM Activities]] | |||
[[Category: STEAM Activities]] | |||