Formula One cars are faster than anything else around a track. While they have amazing top speeds, it’s mainly their cornering ability that sets them apart.
But what allows them to make sharp turns at such high speeds? A large part of it is a thing called downforce.
What is downforce and why do F1 cars need it?
Cornering at high speeds in a car without spinning out requires grip between the tires and the track. The amount of grip is determined by the friction coefficient of the tires and the downward force on the car.
Increasing a car’s weight is one way to enhance downforce and, therefore traction. This approach, however, isn’t suitable for F1 cars as they must remain as light as possible for rapid acceleration.
So, how can downforce be generated without adding weight? The answer lies in aerodynamics, the science of how air moves.
Aerodynamic downforce is like the reverse of lift, which is what aircraft use to fly. With an F1 car travelling at speed, the air that rushes past it does so in such a way that forces the car downwards.
The faster the car is travelling, the higher the amount of downforce. In fact, it is a squared relationship between the two. This means if you double the speed, the downforce magnitude will increase by four times.
The downside of aerodynamic downforce is that it comes with drag. So while it brings significant benefit for cornering, it can reduce straight line speeds. This poses a challenge for F1 design teams, where an optimal balance needs to be found to win races.
How do F1 car wings work?
Wings at the front and rear of a Formula One car generate much of the downforce. They are like an aircraft wing but upside down. Instead of creating lift, they use aerodynamics to push the car down.
Wings create downforce through two mechanisms. The first is Newton’s third law, which states that for every action, there is an equal and opposite reaction. Using this, the upward curvature of the wings deflects air upwards, and in response, the air pushes the wing—and the car—downwards.
The second mechanism is Bernoulli’s principle, which explains that as a fluid (like air) moves faster, its pressure decreases. To take advantage of this, the curved shape of the wings speed up the air along the underside. The result is lower pressure on the underside of the wing, which sucks the car down towards the track.
The ground effect
Since the 2022 season, wings are no longer the primary source of downforce in Formula One. Instead, around 60% of the downforce now comes from a thing known as the ‘ground effect’.
The ground effect is an interaction between the underside of the car and the track. All cars naturally produce some sort of ground effect, either positive or negative. But with the recent regulation changes, F1 cars can now use tunnels on the underside of the car to enhance the ground effect and produce strong downforce.
These underfloor tunnels are often called Venturi tunnels because they use the Venturi effect. The Venturi effect describes how a fluid lowers in pressure as it passes through a tighter section of pipe or channel. The smaller cross-sectional area results in a higher velocity, as the fluid mass flow rate has to remain the same. And as we know from Bernoulli’s principle, this increase in velocity decreases the pressure.
The underfloor tunnels of a Formula One car run from the front and gradually reduce in size down to the throat. Here, the clearance between the track and the top of the tunnel is at its lowest. This is where the Venturi effect does its thing and the lower pressure sucks the car towards the track. From there, the tunnels expand in size through the diffusers where the air exits the back of the car.
The ground effect produces a centralised downforce and provides traction for both the front and rear wheels of the car. The wings, on the other hand, only provide downforce at their respective end of the car.
Why the return to the ground effect in Formula One?
The ground effect is not a new concept to Formula One. Lotus team engineers first started exploiting it in the mid 1970s and allowed them to drastically increase their cornering speeds. Other teams quickly followed suit, and the underfloor became a major aspect of F1 car design.
However, after several seasons of wide spread Venturi tunnel use, rule changes banned them. From 1983, F1 cars were required to have a flat underbody that did not exploit the ground effect. Safety concerns were the reason for these regulation changes. Increased cornering speeds and reliability issues of the tunnels were believed to be causing crashes.
So why did underfloor tunnels return in the 2022 F1 season?
After several decades of wing development, complex designs produced powerful downforces. However, the side-effect was very turbulent air trailing the cars. This affected the performance of following cars and limited their ability to overtake.
So, to make for more exciting and close racing, the FIA governing body needed to find a way to limit the sport’s reliance on wings for downforce. The solution was the return of the ground effect with underfloor tunnels producing cleaner air. Modern design considerations also address the reliability issues the tunnels saw when they were first used in the 1970s and 80s.
