Arthur C. Clark once said that any sufficiently advanced technology is indistinguishable from magic, and that certainly seems to be the case with the black magic studied by aerodynamicists.
That means that we mere mortals often get things wrong when it comes to describing aerodynamics. That difficulty is particularly apparent when it comes to the “drag coefficient” (Cd), much to Jason Cammissa‘s chagrin.
As the YouTuber puts it, the coefficient has nothing to do with size. For example, a person doing a mid belly flop has a drag coefficient of around 1, while a Ram 1500 pickup truck has a Cd of 0.36. So, it’s less about the size than the shape of the object moving through the air.
Read Also: Lucid Air Is The World’s Most Aero-Efficient Luxury Car With A 0.21 Drag Coefficient
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Fortunately, you don’t need to understand how the drag coefficient is calculated to understand what it’s describing. Which is a blessing, because understanding two times the force of drag divided by the mass density of the fluid times the flow speed squared times the reference area (i.e. the drag coefficient equation) is asking for too much from my tiny monkey brain.
Conceptually, the Cd can be understood as how big the frontal area of a vehicle “appears” to the air. So a vehicle with a drag coefficient of 0.5 would appear half as big to the air as a vehicle of identical size with a drag coefficient of 1.0. For what it’s worth, a cube has a Cd of 1.05 but a cube rotated by 45 degrees (so the pointy corner hits the air first) has a Cd of 0.8.
In Cammissa’s example, their drag coefficients mean that a Tesla Model X is smaller than a Lotus Elise as far as the wind is concerned. And now you can avoid being thrown off a tall building by an irritable “know-it-all.”
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