# The important aero parameters for a race engineer

## Aerodynamics: Lesson 1

This articles has the goal to underline briefly the most important aspects and parameters for the general set-up of a racing car. 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)

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).

#### The Aerodynamic Parameters

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

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.

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.  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 difficult to drive.