How to Mod the Aerodynamics on Your Car the Right Way
Every day, you see cars at the track or on the road with aero kits that sit somewhere between aerodynamically pointless and aerodynamically terrible. Some of these are clearly homebrew jobs, while others are just poorly designed "off the shelf" kits that make the car look better, not go better. Of course, not everyone spends their life studying aerodynamics, so some of these are understandable, but lets set the record straight today by showing you how to correctly modify your car for maximum aerodynamic advantage.
Downforce level is related to wing size to an extent, multiplied by the square of speed. This wing for example may be effective if you are travelling at Mach 3.
If you have a car that is exclusively used for regular road driving, and you aren't planning on taking it on the autobahn or excessively speeding, 99% of the time the stock aero on your car is probably best. Manufacturers put a lot of effort into drag and noise reduction, and putting a big wing on the back of your car is going to hurt your economy. At legal speeds, downforce has precious little effect unless you're super light or have a crazy aero kit, if you're feeling a difference on a regular road car it's probably either in your head, or due to that extra 5 kg you just added high up and far from your CG.
A lot of ecomodders have done good work on reducing drag on road cars, typically by streamlining the cars and closing off as much cooling as possible. There's also other ways of reducing drag, such as flat extension spoilers which promote clean separation, check the video for more information on that.
Some of the best low speed aero in the world is on Formula Student/FSAE cars. These cars have teams of aero students working on them and rarely go over 100kmh, meaning they have to maximise downforce to work effectively.
For track specific cars, you have to match your aero level to your speed and power level. Low speed track and high power? Set the aero to insane. As your speed increases you have to worry about drag more, so either you need more power, or you have to back off the aero a bit. The balance between drag and downforce has to be worked out on a car to car basis, however you often find that a car will be faster around a track with more downforce and drag than you initially thought.
WTAC cars have the most aggressive aero of any touring cars. My favourite, RP968, was designed by Sammy Diasinos, ex-F1 engineer, and makes considerably more downforce than an F1 car.
For very high speed applications, such as land speed record cars, it is important to minimise drag, whilst having a very small amount of downforce to ensure stability. Aero balance is critical here to ensure your car doesn't get loose at high speed. You also have to look at the lateral center of pressure of the car, and always try to have the car acting like an arrow and trying point straight. To this end, shark fins and tail fins are effective tools.
For more details on the specifics of how to effectively modify the aero on your car, check out the video below!
Kyle Forster is a qualified Aerodynamicist, race car engineer, and the man behind JKF Aero, a firm that offers a variety of aerodynamic consultancy services for racing purposes. If you have any questions for Kyle or have any suggestions for future videos, drop them in the comments below!