Few subjects are discussed more keenly in Formula One than aerodynamics. Expressions like ‘dirty air’ and ‘barge board’ are now as much a part of the F1 vernacular as ‘oversteer’ or ‘understeer’. Time and again, you’ll hear a commentator say that due to a collision slightly damaging his ‘rear diffuser’, a driver’s race will be fatally compromised.
But what does this actually mean? What do we really understand by aerodynamics in Formula One and why can a small impact make the difference between success and failure? To answer these questions, we engaged the expert knowledge of Aerodynamic Group Leader, John Owen.
Put simply, aerodynamics deals with the flow of air and how it reacts with bodies in motion. A windmill and an aeroplane are both examples of aerodynamics in action. In the early days of Formula One, teams were solely interested in streamlining their cars. In other words, they would seek to reduce the cars’ resistance to the flow of air, otherwise known as drag. The less drag a car has, the less power is required to push it through the air and the faster it goes.
This remained true until the 1960’s, when F1 teams started to dabble with the phenomenon of downforce. The engineers started to understand that by increasing the downward pressure on the tyres, they were able to increase the friction between the tyre and the road and generate more grip. This is because the adhesion is roughly proportional to the downloading on it. They learnt that not only could the car
corner more quickly, but it could also transfer more power to the road without generating wheelspin.
The creation of downforce relies on two age-old theories: Newton’s theory that energy cannot be created or destroyed, just transferred; and Bernoulli’s principle that relates an increase in flow velocity to a decrease in pressure.
“Formula One reverses the principles behind an aeroplane wing,” explains Owen. “In simple terms, an F1 wing is designed so that air flows more rapidly over its lower surface than the upper. This creates an increase in pressure on the top surface compared to the bottom. The resulting pressure difference creates a downward pressure, which we call ‘downforce’.”
Try pushing a pen around your desk. If you only apply a sideways force, it’ll move easily, but if you apply a downwards pressure while attempting to move it, it’s much more difficult – the pen has more grip. You are simulating the effect of downforce on a Formula One tyre.
This relatively simple concept is made more complex by the relationship between downforce and drag. If you compromise the car’s streamlining by deliberately disrupting the airflow, you generate drag, which compromises the car’s straight-line performance. In the ’60’s, F1 teams got around this problem by employing moveable wings. Their angle of attack would be increased in the corners to generate downforce and then reduced on the straights to minimise the drag.
But it wasn’t long before the Formula One regulations banned the use of movable aerodynamic parts. From then on, F1 teams and their drivers had to find the best compromise between downforce and drag. There’s no point being quick on the straights and slow in the corners, or visa versa. That’s why we continue to hear of high downforce set-ups for twisty circuits such as Monaco, and low downforce set-ups for fast, flowing circuits like Monza.
In 1978, Lotus thought they had effectively solved this conundrum when their designer, Peter Wright, discovered ‘ground effect’ aerodynamics. By running the car very close to the ground and controlling the flow of air under the car, Lotus was able to dramatically increase the level of downforce without a significant increase in drag.
‘Ground effect’ cars were banned for the start of the 1983 season, but despite the governing body’s best efforts, the basic principles still form a large part of the aerodynamicist’s thinking to this day. “By accelerating the air away under the car, you get the same effect as a huge vacuum cleaner sucking the car to the floor,” explains Owen. “That’s why we run the ride height as low as possible. The same phenomenon explains why birds are able to fly so effortlessly close to water.”
The airflow under the car is in part controlled by the rear diffuser – the sculptured device that’s visible at the rear of every modern grand prix car. The design of the diffuser is of paramount importance because the quicker the air can exit the car, the more downforce is produced.
More often than not, it’s the bits that you can’t see on a Grand Prix car that make the most difference. “It might sound strange,” says Owen, “but aerodynamic success in F1 today is defined by how you control the airflow under the body.”
Some of the most visible aerodynamic addenda, such as the barge boards – the vertical plate-like structures that sit behind the front wheels – are actually designed to manage the underbody. “Imagine taking the plug out of your bath. You create an area of low pressure, which the surface water is sucked into,” Owen explains. “This is called a vortex. A bargeboard creates about ten different vortices, which roll up into one under the car. This creates an area of low pressure under the car, generating more downforce.”
The front wing endplates play a similar role. “They create four or five separate vortices and they control how the air interacts with the front tyres.”
The tyres on a grand prix car remain the bugbear of an aerodynamicist’s life. “They are a very bluff shape and they create a lot of turbulent air. Many of the features of a car, such as the endplates and bargeboards are designed to stop this turbulent air getting under the car.”
Not surprisingly, the front wing is the key to the aerodynamic concept of the whole car. “The air first experiences the front wing and it defines how the air will flow down the whole car. This inevitably involves some compromises. By the time the air arrives at the rear wing it is travelling around 30% slower than it is at the front. The rear wing is much less efficient that the front wing or the underbody – in other words, for every Newton of downforce, you generate much more drag.”
Over the years, the F1 regulators have worked to reduce the amount of downforce generated by the cars and with considerable success. “If we were given free reign, we’d quickly generate at least twice as much downforce as we do now,” says Owen.
But just as the regulators have become more adept at reducing downforce, so the teams have introduced more and more sophisticated designs. The latest wind tunnels and Computational Fluid Dynamics (CFD) techniques have resulted in an extraordinary attention to detail. “Complex shapes are now easier to manufacture than ever before. I could change a few details and the car would lose 10-20% of its downforce, but only the trained eye would be able to spot the difference.”
In a sport obsessed with attention to detail, the aerodynamicists are more obsessive than most. But for all the technology and all the sophistication, aerodynamics remains something of a black art that consumes some of the world’s finest brains. “A ten per cent improvement in downforce is worth about a second a lap,” concludes Owen. “And it’s our job as aerodynamicists to find it.”Related newsarticles:
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