What Is Downforce?

This is a crucial component to stability and grip.

byPeter NelsonJul 5, 2022 3:30 PM
What Is Downforce?
Peter Nelson
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Each minute exterior detail on top-tier consumer performance cars like a McLaren 620R and professional race cars like an IndyCar or Formula 1 car is designed to make mechanical physics work to the driver's advantage. Every millimeter of bodywork makes a difference in how the vehicle drives and performs, and the car's relationship to the air it's cutting through is paramount. A crucial part of this relationship is downforce, which can be harnessed and applied by aerodynamic parts throughout the car's shape. The science of downforce can get fairly deep, but we're here to give an overview of what it means and a breakdown of why it's important to driving execution.

To define downforce with just a couple of words, it is vertical load created by a vehicle's aerodynamic parts as it's in motion. To boil it down even further, a car’s exterior components split, route, and direct airflow in a way that pushes the vehicle down and increases traction and stability. Front splitters, canards (also known as dive planes), rear spoilers, front spoilers, those massive adjustable air foils that Chaparral affixed to their badass Can Am race cars back in the day, and other aerodynamic bits all create downforce. Downforce keeps cars planted on the road at speed and ensures the tires are pressed firmly onto the road for maximum grip.

What's cool about downforce is it can be used at both high and low speeds relative to the capabilities of the vehicle. Downforce is often associated with high-speed driving, especially cornering, such as an IndyCar that needs every teeny bit of grip it can muster as it courses through the Long Beach Grand Prix circuit. The Dallara-designed chassis is a prime example because of its heavy use of aerowork. 

However, downforce plays into low-speed performance, too—this is why you'll often see heavily modified autocross cars with massive wings. Despite autocross courses often featuring low-speed sections in their tight courses, cars with wings that have a lot of surface area can still use that air to help stay planted and shave thousandths of a second off of their run times.

Where downforce matters the most: a slow technical section of the Long Beach Grand Prix circuit. Check out the angle on those front bits, as well as the rear spoiler.

Depending on the circumstances and the type of driving, vehicles can have too much downforce, or even unbalanced downforce. Because of the added weight caused by downforce, an improperly adjusted wing or spoiler could cause too much aerodynamic drag and slow the car down, especially if the car doesn't have a good enough power-to-weight ratio. This is why any wing worth its weight in grip is adjustable, meaning you can alter the angle at which air contacts and moves over it. Some can be adjusted two or three ways while many professional applications can be adjusted more than 10 ways. Many other parts of a race car’s aerodynamic kit are adjustable, as well, particularly at the nose.

Downforce is vital in corners as well as during braking. For tracks with more straights and fewer low-speed, technical sections, the angle of the car's various downforce-adding components aren't as significant, meaning they're positioned to still produce downforce without causing as much drag. For tracks with more low-speed, technical sections and fewer straights, these components will be positioned to have more of an angle to add more downforce to increase cornering and braking grip, as drag is less of a concern.

Balancing downforce is crucial, too. If a car has a massive wing out back and no front splitter to balance it out up front, the car might exhibit understeer as the rear wing is unloading the front end and stealing crucial grip. Suspension tuning also has a hand in this, but we'll save that for a future blog.

Downforce is a crucial component to performance driving and even possesses stability-improving benefits for street cars, too, like its integration into the original Audi TT to keep its rear in check. We hope you dig this basic explainer and follow along as we discuss more about aerodynamics in the future.

Video

In this quick clip, pro driver Nelson Piquet Jr. explains the basic aerodynamics of a Formula E car and how downforce applies to those race cars.

FAQs About Downforce

Q. Does downforce slow a car down?

A. There's always a compromise between downforce and drag, and it all comes down to the chassis that's being used and the track it's running on. If the car has a lot of downforce, this will slow it down on a straight.

Q. Is downforce in a car good?

A. Generally speaking, yes! But too much can create drag, which will slow the car down and decrease fuel economy.

Q. What does low downforce mean?

A. This means the car will have more speed in the straights, but less grip in the corners. The opposite is high downforce.

Q. How is downforce calculated?

A. Occam's Racer has a great explainer on how a wing's downforce is calculated, which is using the equation: downforce = 1/2p * A * Cl * V^2. It includes some nifty links to continue figuring out scientific measurements, too. To dive a bit deeper, Formula1-Dictionary.net has a thorough explainer on calculating a vehicle's overall downforce.