What Is Aerodynamic Braking And Is It Used In Cars?

When we think of braking systems in cars, there are probably a few setups that come to mind. Drum brakes and disc brakes are different, but they are the most commonly thought-of braking systems, using physical clamping force and friction to slow a vehicle. Then, there's regenerative braking, generally used to re-capture energy through electric motors as we bring EVs or hybrids to a halt. A term borrowed from flight, aerodynamic braking, could also apply to some cars. 

To put it in simple terms, aerodynamic braking uses drag to slow down a vehicle, and when landing a plane, aerodynamic braking is used to reduce the reliance on physical brakes. Does the same theory apply to cars? Can you use aerodynamics to slow a car down instead of the brakes?

Drag is an aerodynamic force that slows all moving objects as they move through the air, including cars, but it will take quite a long distance to stop a car using aerodynamics alone. So, sure, you can slow down by taking advantage of things like drag and gravity. Just like with a plane, however, you'll likely want to introduce some friction braking too. Where you're most likely going to see aerodynamic braking on cars is in the use of active aero to supplement friction-based braking.

Active aerodynamics are used for braking purposes on some of the most-expensive and highest-performing cars on the road today. The Bugatti Veyron, for example, is one of the most-powerful and fastest supercars ever, and it uses a massive rear spoiler to add braking force. 

The airbrake, or aerofoil as Bugatti calls it, springs into action when the driver presses on the brake pedal. When a certain amount of braking pressure is sensed, the Veyron's rear wing changes its angle to increase wind resistance and slow the car down. Then, when you step on the gas again, the aerofoil shifts back to its original position, reducing the wind resistance.

The McLaren Elva uses its active air management system to divert air around the driver without a windshield. With the Pagani Huayra, active suspension is linked to active aerodynamics to improve braking stability, and even on the new track-focused Ford Mustang GTD, there's a hydraulically-controlled system that can adjust the angle of the rear wing to increase forces like downforce and grip. Of course, Formula 1 cars use DRS, or drag reduction systems, which take advantage of the same laws of physics in their own way. They use active aero to reduce drag and increase speed.