CO2 dragster

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CO₂ dragsters are miniature racing cars racing with suspenders powered by a rocket launcher carbon dioxide cartridge. They are frequently used for pedagogic purposes in demonstrating mechanical principles. A set of two hooks (eyelets or screw eyes) linked to a string (usually monofilament fishing line)at the bottom of the car prevent the vehicle from losing control during launch. In a race, a laser scanner records the speed of the car at the end of its run. Often, the dragster is carved out of balsa wood because of its light qualities.

CO₂ cars are model dragsters designed and built by students that are to be designed aerodynamically to race against one another. Wooden dragsters are made from basswood or balsa wood are designed, constructed, and shaped with plastic. Students start with a block of wood , A saw is used to shape the body into the design according to the student. Axles and wheels get the car moving down the drag strip. The most well known and common producer of these kits is Pitsco.

CO₂ Cars are a preferred favorite for engineering curriculums worldwide. Students learn about the forces of drag, wind resistance, and the motion of air as a fluid. Thermodynamics are also somewhat involved. The project mainly tests the aerodynamic properties of a student's car (see also aerodynamics).

Shell cars are designed with the wheels on the inside of the car. This is a very good choice for students who want to reduce a lot of drag. Shell cars are classified by "encapsulated" sections on the underside of the car.

Contents 1 Dragster Parts and Assemblies 1.1 Wheels 2 Headline text 2.1 Body Blank 3 How the Metric 500 Works 4 See also

[edit] Dragster Parts and Assemblies

[edit] Wheels

Wheels are the objects that keep in contact with the ground and allow the dragster to move forward. Wheels come in many different shapes and sizes. As wheels roll forward on the ground, they cause friction (which cannot be avoided). As wheels roll on the axles (shell designs) this will cause friction. Friction will slow down a car along with drag. Common wheel models include:

• GT-R (Rear) Wheels
• GT-F (Front) Wheels
• Pitsco *Delrin (Front) Wheels*
  • Delrin is a better quality plastic that Pitsco uses for its premium wheels. Delrin is pliable and a lot easier to work with and shape. Delrin also does not have any "gates" sticking from the wheels like most injection mold plastic wheels do.

[edit] Headline text

[edit] Body Blank

The Body is a 12" long by about 1" wide block of wood that can be mistaken for a doorstop. This blank is modified by carving, drilling, sculpting, and cutting to form the body of the CO₂ car. The most common blanks are made of Bass and Balsa wood. Students choose Bass wood for weight, but Balsa is usually a better choice for light and fast cars. Balsa wood is also well known in the model building field, and is extremely easy to work with. A downside, however is an overzealous student may remove or cut too much balsa wood than expected, commonly with a gouge or dremel power tool.

[edit] How the Metric 500 Works

Beginning .100 seconds into a CO2 Dragster race. High Speed camera photo of two dragsters racing 65.5 feet in about 1.000 second.

A student setting his dragster up for the CO2 Car race.

High speed shot of a race about .750 seconds in.

Dragsters race down a

20 meter track (about 65 feet, 7 inches) down a filament line (usually fishing line) that goes through screw eyes placed on the underside of the car. With these, the car will travel in a straight, linear path through the finish line.

Students first place the CO₂ Car on the filament line, and check to make sure cars are in good repair and are ready to race. CO₂ cartridges are inserted into the powerplants, and the cars are lined up behind the starting line. The starter boxes (the device that allows the cartridge to be punctured) is adhered down with velcro at the beginning of the starting mat. Dragsters may be placed anywhere in the starting area, so long as the front of the body (usually the nose) is behind the red line (Adding to this, a shorter car does not necessarily mean the car is a faster one). The starter boxes can be adjusted by loosening a lever 90 degrees to accommodate for the height of the dragster. Once the neck of the cartridge is lined up with the pin, the neck is fitted into a tube in the starter box. The lever is switched back up 90 degrees to indicate a racer is ready. In most shop classes, from this point on the car is impounded and you may no longer touch it.

In TSA finals, professional staff will handle all CO₂ Cars, repairs (and final touches) must be attended to BEFORE entry. When both cars are ready, the central computer is on standby to launch the dragsters. The instructor should check everything for safety, and will order all racers and participants to step away from the track. The timer is activated (With the Impulse II System) and in 10 seconds both pins will puncture both CO₂ cars at the EXACT same time. From the time that master button is pressed, it will all be over in 11 to 12 seconds.

Most racing systems have a laser system to judge how fast a car was going from start to finish. Computers greatly aid in this process. Most Pitsco racing systems are accurate to a thousandth of a second (0.001). Times will display either on a connected computer, or in the LED lights of the racing system itself. Most Pitsco racing systems accomplish this with invisible laser beams that are projected downwards or from the sides. Once a beam is broken, the time the computer released the puncture pins to the time the laser is broken will determine a car's time. Towels or a block of foam (or other type of padding) slow the dragster to a halt and prevent damage to people, objects or to the cars themselves.

[edit] See also

• Pinewood Derby
• F1 In Schools