MadSci Network: Engineering |
Aerodynamics is nothing more than changing the shape of a car to change how the air moves around it. Air has mass and will resist things moving through it. Ever put your had out the window of a moving car? Did you ever notice that if you turn your hand sideways, the air doesn't push on it as much. Basically, that's aerodynamics. The goal of the vehicle designer is to minimize this effect on a vehicle. There are a few ways to do this. 1) Minimize the total frontal area of the vehicle. Obviously a dump truck has to push more air out of the way than a motorcycle. 2) Make the air move more easily over the vehicle. A vehicle that is 'blocky' in shape (like a jeep) won't let the air flow around it as easily as, say, a corvette. Also, ever see a wide piece of plastic sticking down under a car, up front, just before the engine? That's calles an air dam and is used to deflect air away from the underside of a vehicle. All the pipes, tubes, and other things under a car cause a lot of drag. The goal is to get the car to move through the air rather than pushing it out of the way. Engineers use wind tunnels to fine tune the body design. The vehicle designer can also use the air to change the way the car performs by channeling air to cool brakes or funnel air to the radiator. The big 'tails' you may have seen on race cars use the air to push down on the rear end to give more traction (this is called downforce). The wings you see on most cars on the streets are mostly for looks. Having a design that is good at moving through the air is called being 'aerodynamically efficient'. The same thing applies for anything moving through air (or water, or anything that has mass) such as ships, airplanes, fan blades, rockets, submarines, fish and frisbees! Better efficiency means better gas milage and less power needed to move the car at highway speeds.
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