Some physics behind Formula 1

A grand day out

Last month we had the fun experience of going to a racetrack to watch and excitingly also drive some fast cars with big names in the motor industry, specifically the McLaren 570s, Ferrari 458 and Lamborghini Huracan 1.

It was a sunny day on the race track, and all the cars flew around them beautifully, their powerful engines roaring as exhilarated drivers zoomed them around the track. While a fun day in itself, it got me wondering about the physics behind their design. But what exactly makes these cars so special? Here I'll dig a little deeper into the engineering behind some of the fastest cars in the world.

Above: sunny scenes at Prestwold Driving Centre, with the McLaren in orange, Ferrari in black and Lamborghini in blue, all of which went very fast with a lot of noise, and the first of which opened its doors upwards, as though it was preparing to take off.

Our favourite car of the day was the McLaren, not only for its striking orange colours and British history, but also because of their prowess elsewhere. McLaren is enjoying a lot of publicity at the moment through its Formula 1 team, where Lando Norris, the youngest ever British F1 driver, and Australian Oscar Piastri are regularly in the headlines and on screens for driving some of the fastest cars in the world. While the cars we drove were 'only' supercars, not F1 cars, apparently they can hit similar speeds, although for obvious reasons amateurs were accompanied by instructors and limited in their speed around the driving centre, which while above motorway limit, were nowhere near the maximum speed the car could achieve.

Formula 1 and slot cars

The sport of Formula 1 is so called due to the strict rules to which both vehicles and drivers must conform, hence 'formula'. This puts me in mind of the Scalextric sets I sometimes played with as a child (for those who don't know, this is the petrolhead's equivalent of model trains, where tiny F1 models are attached to a plastic track with magnets on a singlar tramline slot design, and remote controlled by a person holding a speed controller in their hand). In both the real sport and the model sets, one wins by completing a circuit first, and in both, there are strategies to help do this, some of which are banned, others of which are not. A toy F1 car will need to speed up on the straight parts and slow down around the bends, otherwise it will fly off the track and crash into a wall, which is something that definitely did not happen to me on a regular basis when I had my thumb flat on the controller making the car run at full pelt. Eventually, to stop this happening, we modified the car so that it could go around the bends faster without flying off, by putting stronger magnets in the bottom of it which would keep the car more firmly attached to the track surface even when changing direction at high speeds. While this was technically cheating, as my car was modified to be able to go faster than an ordinary slot car, it got me thinking how other winning strategies are adopted by professional F1 teams.

A model F1 car on Scalextric track, image credit Chris Lobina, SWNS.com

In the real sport, teams of engineers and physicists are employed (at a cost of several million pounds) to make these cars as efficient as possible while still adhering to strict and ever evolving rules. Some specifics about the work that goes into the design of these cars are closely guarded engineering secrets, as teams do not want to share their successes with rivals, however, there are some fundamental basics to F1 car design.

Downforce

The single biggest performance differentiator in F1 is the manipulation of air around a car, which plays into all other factors of how fast a car can be driven. In a similar way to my magnets in the model car, the primary aim of aerodynamics is to generate downforce to push the wheels harder into the road, or in my case, keep the magnetic bottom of the car firmly on the track. This gives the tyres more grip, which means faster speeds around corners (no more flying off the tracks!), harder acceleration and braking, and ultimately faster times on the circuit. Downforce is generated by every surface on the car that touches the air, primarily the car's floor, but also its front and rear wings, which can be adjusted in angles to provide different amounts of downforce levels. However, it isn't as simple as generating as much downforce as possible, since F1 cars are driven in many different weather conditions, and there is no single perfect car for all scenarios. F1 cars lean to their sides around corners, dip down at the front on braking and at the rear when accelerating, often doing two of the three at once, and the design of the car must be able to withstand all of these. Downforce should be predictable and consistent in all conditions, and the refinement on design takes a lot of computational numerical simulations and practical tests in wind tunnels, the engineer's equivalent of a physicist's lab. The consequences of getting this wrong can be disastrous. Understeering occurs if the aerodynamics don't push down enough at the front of the car, meaning it can't steer into corners and will crash. Oversteering on the other hand, occurs when the back wheels slide and can result in the car soon facing the wrong way. Performing a three point turn on an F1 track to get your car's nose pointing the right way again while others zoom past at 180 mph is obviously to be avoided.

A sketch of an F1 car from 2021. Car designs may differ slightly year on year, depending on new regulations. Image credit: BBC Sport, The Secret Aerodynamicist.

Wake

Another important part of the aerodynamics is the wake, the turbulent air left behind an F1 car as it drives. It is quite difficult for F1 drivers to get close enough to the car in front to overtake, due to wake, the name of churned, turbulent air which comes off the black of F1 cars. This is similar to the swirling, churned water seen immediately behind an oar that has been pulled through it. The type of air that F1 cars pass through determines the amount of downforce that can be generated. Downforce is generated by low air pressure underneath the car, which is lowered by increasing the car's speed. When a car drives through smooth, calm, 'clean' air, the surfaces producing downforce work well, meaning the car can get a better road grip, and go faster, etc. On the flipside, if the air is turbulent and messy, this doesn't work so well. So, if your car is following another car, you'll be driving through turbulent, 'dirty' air which has partly been dragged along with the car ahead, meaning the air isn't travelling towards you as fast as it was for the car in front. It will therefor not travel under the car as fast as 'clean' air, meaning your car will have less downforce and subsequently less grip and less ability to speed around corners. This problem has been looked at by regulators, with new rules dictating the geometry of allowed designs, to minimise wake for the cars behind, making it easier to overtake. It also makes for more exciting races for spectators if the order of the cars in the race can change more easily.

Tyres

Cars would go nowhere without the wheels that carry them, and in turn their tyres. All F1 tyres are provided by the same supplier, Pirelli, and are the same diameter across. However, the tyres come in five different types, known as compounds, which have different properties so the car can be adjusted to deal with different driving conditions. On each team, a strategist will advise which tyres are most suitable, or if they need changing, depending on the conditions for the race that day. Softer tyres will heat up quickly if the track temperature is higher than anticipated, meaning they will last a shorter time and are more likely to need changing. This changeover time, known as a pit stop, can cost a driver crucial seconds during the race, so getting the decisions on tyres right can be vital in determining who handles the conditions best on the day. By contrast, hard tyres heat up more slowly, so if the race track is colder than expected, the warm up time for the tyre will be longer than expected, and the tyre will be worn down more before it has the chance to warm up, which can affect the rest of the performance in the race. Tyres can help mitigate the effects of track temperature on performance, and their different tyres are also needed depending on how wet or dry the track is. If the weather changes in the middle of the race and it suddenly starts raining, tyres need to be changed to adapt to the new conditions. Again, this adds to the drama of the sport, where strategic decisions can clinch victory at the last minute.

So there it is, a brief whistlestop tour of some of the physics behind the world's fastest cars. While there is plenty more to it, this article covered the key basics behind F1 engineering, which should go some way to explaining why teams spend so much money and effort on redesigning their cars every to make them the fastest cars in the world.