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Lube 4 Speed: Heard of dry powder graphite? It's a great lubricant for axles. More Tips |
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As the racecar travels down the track, it moves through a fluid. Most people don’t think of air as a fluid, but it is. While in motion, the car’s surface contacts air molecules. Because there is relative motion between the car and air molecules (the car is in motion while the air is stationary), friction occurs.
Fluid friction contributes to aerodynamic drag, which is a resistance to the forward motion of a body through a fluid (the air).
Automotive engineers test their designs in wind tunnels. A wind tunnel simulates road airflow conditions by moving a stream of air around a stationary car. The speed of the moving air can be varied from very slow speeds to fast highway speeds.
Well-designed wind tunnels produce a laminar airflow. Laminar flow is a straight, layered flow of air without turbulent air pockets known as eddies. It is desirable for a car in the tunnel to disturb the laminar flow of air as little as possible. Features such as large side mirrors jut out into the air stream and cause turbulence. The presence of turbulence increases the aerodynamic drag, which resists the car’s forward motion.
CO2 racers can also test their cars in a wind tunnel. Several tunnels are available, including Pitsco’s AirTech X-Stream Wind Tunnel, which has a 12" x 12" x 24" test chamber and produces an excellent laminar air stream. It measures the frontal drag force in grams. An add-on accessory called the Fog Maestro enables the introduction of a visible vapor
 into the test chamber, clearly indicating any turbulence generated around the car body.
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