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3 Reasons why aerodynamic drag is so important for automotive design

3 Reasons why aerodynamic drag is so important for automotive design - Blog

Aerodynamics is one of the most beautiful and intricated parts of engineering and of the design of a car. It involves mind-bogglingly complex physics and mathematical models that can trick even experienced engineers. In this colossal puzzle, drag forces have an enormous impact on the automobile’s performance, with some badly-designed aero resulting in great losses in performance terms. As technology advances and more tools are being developed to find better solutions, automotive aerodynamics is getting more complicated and more efficient for performance (and mother nature’s) sake. So here are a few reasons why drag plays a big role in a car’s design.

1. Minimizing drag can save huge amounts of fuel

Drag is nothing but the force your car will be subjected to when carving through air and it can be caused by many phenomena. However, it will always be a force acting in your car that is exactly against your movement. Thus, the more drag your ride produces, the more fuel it will need to use in order to overcome this force. Some sleek design is fundamental for fuel economy. Take the Tesla model S as an example. with a drag coefficient of 0,24 (drag coefficient: an adimensional coefficient that measures drag, Cd, as it is normally abreviated, for a regular hatchback is around 0,3~0,4), being able to have that absurd range of up to 295 miles. Less drag means less energy spent for cruising, which means you can better use that lovely petrol/electric energy you so desperately need and mother nature can have less pollution, so you can hoon around in a cleaner world!

Tesla model S. Designed for aerodynamic efficiency.
Tesla model S. Designed for aerodynamic efficiency.

2. It also has direct relation to the maximum speed of your ride

Yes, reducing drag is an excellent idea to the “go faster” way of life. This falls on the same thing as fuel efficiency. As the car will have smaller forces acting against the car’s movement, it will be able to transfer more of that power produced by the engine into movement, remembering drag increases with the square of speed, reducing a car’s drag coefficient results in much higher speeds. Take the 1980’s cars as examples. Their boxy shapes had humongous amounts of drag; when they had bodywork replaced in the 1990’s, top speed increased by 20Km/h with the exact same engine, suspension, tires etc. Interestingly, F1 cars have loads of drag. Their Cd ranges between 0,7 and 1,1, depending on the downforce setup used. This is some tricky information though, as F1 cars need loads of downforce to maximize cornering speeds. This doesn’t mean the engineers just don’t care about drag; on the contrary. They need to find a design which will maximize downforce and minimize drag. This is the beauty of engineering.

The beauty of engineering!
The beauty of engineering!

3. It will also affect handling

The drag forces will be applied directly into the pressure center, not the center of mass. Thus, these forces can generate some torque, which can unload the front or rear wheels, turning the car in a possible understeer monster. So drag is also important for that track day (bro!) and racecars.

This square Gol GTi had a top speed of 185 km/h...
This square Gol GTi had a top speed of 185 km/h...
While its sleek successor had a top speed of 205 km/h with no significant mechanical changes,
While its sleek successor had a top speed of 205 km/h with no significant mechanical changes,

This is it! What do you think? Drag is actually so important to autmomotive design? Would you get a powerful car with the aerodynamics of a brick or a sleek, but less powerful car? Leave your opinions in the comments!

Hope you enjoyed!

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