The aerodynamics a stock car goes through during a race displays fundamentals in fluid mechanics. The car experiences drafts, drag, ground effect and down forces.
Aerodynamic Factors: .
• Down Force.
• Drag.
• Ground Effect.
• Draft.
.
Figure 1 (Pressure Differentials).
Airflow is the prime factor in car design for racing. Producing more down force gives a car more control and stability but sacrifices speed. Car designers use fluid mechanics to find a properly balanced net down force for each car. .
Racing teams have found a number of ways to increase the stabilizing downward pressure on the car. There are air dams or valances below the front bumper, rocker skirts below the side panels and spoilers on the rear deck. Spoilers are 57-inch-long flat panels about 6 inches tall, set at angles of as much as 60 or 70 degrees. Of all the down force enhancers, they figure most prominently in the aerodynamic strategy of racing. While necessary to give racecars adequate traction, down force becomes particularly critical in turns. .
Drag is created from air pressures flowing over the car; drag is the car's enemy because it robs horsepower and speed. .
Figure 2 (Pressure Top View).
Ground effect is another factor in racecar design; this is caused by the change of airflow around the car because of its closeness to the ground. Draft occurs when cars are traveling close to one another; when a car is traveling at high speeds behind another car, it forces the car in front of it to take the load of the air resistance. As a car is speeding along a racetrack, some air tends to pile up in front of the car and air gets dragged along in its wake. A small resemblance of a vacuum occurs and air will gradually move in and fill the depression of low-pressure air. .
Draft:.
Most of the horsepower generated by an engine is eaten up by the high-pressure air pushing the front of the car and the low-pressure air (a partial vacuum) dragging at the car from behind.