I'm sure that everyone has at one time or another been caught doing this. It is also possible that your parents told you to stop doing it or bad things were going to happen. Clearly, I am talking about sticking your hand out the window of a moving car. Parents can be such buzzkills! Until you were told to stop, you could feel the force of the air against your hand. It was something unseen, but you knew there was a force there. If you placed the palm of your hand at a right angle to the ground, you could feel the force against your hand and arm.

Conversely, by placing your hand parallel to the ground with your thumb or little finger cutting into the wind, you would feel an instant reduction in force against your arm and hand. You could change the angle of your hand and drive your arm up or down, depending on the position of your hand. You also knew that the faster your dad or mom would drive, the greater the force on your arm would be. This simple experimentation was your first foray into aerodynamics. You were experiencing the force of air-even if you didn't know it at the time. From an engineering perspective, you were feeling the force of a fluid as it acts on a solid object moving through it.

There is a great deal of energy in moving air. Just look at the damage that can be caused by a storm or the unfortunate consequences of hurricanes that have recently plagued the Southeastern portion of the United States. Just as there are great amounts of energy in moving air, a great deal of energy is expended when moving your race car through the air by the simple act of accelerating the car around the track. If you can reduce the amount of parasitic drag draining your energy bank, you could use that surplus energy (horsepower) to accelerate the car.

We all have listened to the race announcers talk about aero-push, slipstreaming or drafting, and getting the car in dirty or clean air. It is clear that on larger tracks there is a very strong effect on the car as it moves through the air. If we add more cars to the picture, the situation gets more complex and exciting. What many racers do not realize is that the effects of aerodynamics start to act on the car at speeds as low as 45 mph. Many short-track racers do not even think about the forces that the air generates for and against their cars. They seem to focus on the more visceral aspects of short-track racing. We all know that cars can reach speeds of 90 to 100 mph on a quarter-mile track, and the speeds are even higher on half-mile tracks. The cars will go even faster with added banking.

Let's spend some time talking about air and the speed you can gain by learning to work with the flow instead of going against it. First, as with any discussion, we need to have a common language. Please remember that air acts like a fluid, but it is compressible and its density varies as the weather changes.

Aerodynamics: The study of the motion of fluids (in this case air) on an object or objects and the forces created by the motion of the fluid or the motion of structures within the fluid. This is a very high-level definition. For the purposes of this discourse, we are concerned with the forces generated on a race car as it passes through the air.

Airflow/Air stream: The flow of air around the race car-front, sides, top, and bottom.

Cd: The coefficient of drag or drag coefficient. This is expressed as a number that represents the amount of drag a body creates as it passes through the air. The lower the Cd, the better. It is commonly expressed in numbers less than 1.

Drag: A force that acts against a body moving through a fluid. In our case, the fluid is air. Drag is the friction or resistance that the air generates as the body moves through it. Drag acts in an opposite direction to airflow. In our application, it's opposite to the direction the car is heading. The lower the Cd, the lower the drag that is generated as the car is moving through the air. Drag has two components: parasitic drag and induced drag. These constituents of drag are all contributory to total drag. This is a bad thing. We want to try to reduce drag if at all possible.

Downforce: A downward force generated as a body moves through a fluid. As racers, we need to balance the amount of drag versus the amount of downforce. The two are very different, and the results of each are very different in respect to improving vehicle performance. In an ideal world, we would try to increase the downforce and reduce the drag. An increase in downforce does not necessarily indicate that we will be able to reduce drag. Conversely, an increase in drag does not mean a decrease in downforce. The two are linked but not mutually exclusive.