# The most important aerodynamic coefficients for racing

## Aerodynamic coefficients and race engineering

This articles (for the previous ελέγξτε εδώ) has the goal to underline briefly the most important aspects and parameters (in particular the aerodynamic parameters) for the general set-up of a racing car. A particular focus is made on aerodynamic coefficients. Immediately we have to ask ourself 4 main questions about the car we have (or we want to study):

1. What’s its shape? (external shape, ducts presence…)
2. What’s the aerodynamic configuration? (front and rear wing, aero devices)
3. What’s the mechanical configuration? (tyre assembly, suspensions)
4. What’s the general setup? (height form the road, yaw, steer and roll)

### Aerodynamic coefficients to represent vechicle performance.

The answer to these questions are the way to produce performance. At the same time, when we know what’s our car baseline we need to specify the flow conditions. The same car will respond differently if flow direction, velocity magnitude and environmental parameter are different. In a related article we’ll see which are the parameter the engineers can control to produce performance. In the following photo we can observe which are, for example, the aerodevices in a racing car (covered tyre configuration).

#### Which are the most important aerodynamic coefficients?

All the students of aerospace engineering may have heard about the so called coefficients of pressure, force και momentum. However they tell you only how good is the adimensionalized shape of your object:

#### Introducing adimensionalized aerodynamic coefficient.

In fact, what physycs really reads are the dimensionalized ones (if you increase too much the frontal area, the advantage of having an aerodynamic shape is loss!). So, in the next articles we often refer to them treating the performance of a race car.

#### Drag and Lift coefficient.

Coming back to the core of our topic we introduce the parameter a aeroengineer should take into account. We have Cx and Cz (coefficient of drag and downforce dimensionalized), their ratio Cz/Cx (the efficiency) and the balance front who tell us the downforce distribution between front and rear.

#### Downforce and efficiency.

We can already foresee one thing: a team can develop a high efficiency car (low drag and medium downforce) or a high downforce car. The fastest car is the one which can reach the best balance. Morevover, duting the development phase, a car is designed at particular target for aerodynamic and mechanical balance. A car with great downforce but awful balance would be δύσκολο to drive.

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