5 things amateur racers get wrong about aerodynamics | Articles

Bad Question: How Much Downforce Does It Make?

This question is probably the first one that I get asked about an aero device. The real answer is “it depends.” How the device is incorporated into the whole car and the speeds involved are needed to accurately answer the question.

A better question, which should make the questioner think through the entire process, is this: How does this device work with the rest of the car? Adding devices at the back of a body can and often will change what happens at the front. It is a system to be considered as a whole. As a side note, mostly we don’t use forces for comparing aero, we use coefficients that are almost speed-neutral.

Bad Advice: Do It Like the Pros

While imitation is a high compliment, most professional series employ rules and limitations that prevent the engineers from getting too much performance. It might be size, location, adjustability or an outright ban on a device, but the limit is there. Use the pro series configurations as a starting point, not a final destination.

Bad Info: Spoilers and Vortex Generators Reduce Drag

Every time I hear this, I gnash my teeth. While there are a very few instances where this works, it is much more likely that spoilers and vortex generators increase drag. Forcing the air around stuff–like a spoiler–takes energy and therefore creates drag. This is a guarantee locally, but it may reduce drag effects elsewhere, providing a net drag reduction on the car. Remember, the entire car operates as a system.

Bad Plan: Bigger and More Is Better

Even at the professional levels, this crops up time after time. Usually it occurs with things like the angles of splitters and dive planes as well as the angle of…