Aerodynamics and Why They Work: Part 1

Will — Fri, 08 Jan 2010 18:05:27 +0000

Supercars are fast. That’s a fact that most of us know very well. Why, though, do the faster cars have to have all of the aggressive body work that they do? The answer is aerodynamics, and it’s two pronged approach to tackling the dilemma of making a car produce less friction as it cuts through the air and making the car heavier and more stable. For the next several weeks, check back on Fridays to get a more thorough understanding of all of the elements that car designers use to create these stunning vehicles. Today, we will start at the front of the car.

The leading edge of a car is generally called a splitter. This is due to the fact that at this point the air is split, with some of it having to go over the car and some under. This is important because of the differential in pressure that is created in this process. The air flowing underneath the car speeds up creating low pressure. The air flowing over the car encouters a surface with a high angle of attack and forces the car into the ground. The low pressure area under the car sucks it down and the high pressure area above pushes the car into the ground.

The math: D = 1/2 (WS x H x AoA) x F x ρ x V^2

Expressed as a sentence, it reads downforce is equal to one half of the width of the wing times the height of the wing times the angle of attack, the sum of which is multiplied by the coefficient of drag of the wing, times the air density, times the velocity of the airflow squared.

Unfortunately, there is more to a car than just airflow. Radiators, oil coolers, brake ducts, and ram air intakes are a few of a cars components that require airflow to provide cooling. In the picture above, cooling ducts account for a majority of the leading edge of that 911. So in many cases, figuring out a way to cool a car sufficiently and keep aerodynamic efficiency is of prime concern for a designer.

Next week: the rear wing.

SCV Exotics » splitter

Aerodynamics and Why They Work: Part 1