The critical speed

What makes the Indy 500 unique in the racing environment is speed. The best-qualified car in 2020 reached an average lap speed of more than 230mph.

Clearly, the honour of being the fastest race in the world comes with the burden of many additional and bigger safety issues. The cars are always at the limit of every component’s design range, while the drivers see everything happening at twice the average speed of a normal track. Moreover, doubling the speed increases kinetic energy by four times, so any impact with the barriers, or with flying debris, may potentially be a much more dangerous one.

From the aero side as well, such a condition brings further safety concerns. When travelling at 230mph, the car is subject to almost 3000lb of aerodynamic load, almost twice its own weight. This means the car could easily run upside down, pushed to the track by the air, despite the force of gravity.

It is easy to imagine, then, that when losing control of a car at that speed, taking it out of its design conditions, the forces generated on the vehicle can quickly lead to catastrophic results. In several conditions, especially when air is channelled under the floor, the car can become a lifting body, rather than a downforcing one, and the aero force can overcome the weight of the car, leading to a real take-off.

Aerodynamic stability

So when you are dealing with the aerodynamic stability of such a racecar, the very first thing to work on is to reduce the lift coefficient in any circumstances the car could