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If you’ve ever watched a Formula 1 test session, there’s a pretty solid chance you’ve seen what looks like a chain-link fence attached to the car. As bizarre as they may look, these giant grids play a pivotal role in teams’ unlocking performance. These are aero rakes, giant arrays of Kiel probes mounted on the car to measure air pressure. These rakes come in a variety of shapes and sizes, but all have the same goal: to map and measure the airflow coming off of the car.
Certainly not the prettiest sight on track, but the data it can bring is critical to engineers, who spend months and millions trying to make their wind tunnel simulations as close to real life as possible. Those first sensor reads give the team an instant answer to how close those simulated runs are to real-life, and can help engineers transform their car from bust to beast.
First impressions
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Since the late 1960s, downforce has been the lifeblood of Formula 1, as teams spend hundreds of hours researching and testing to find the optimum way to use airflow to keep their car hugging the ground. Trying to keep costs down and competition close, F1 has reduced this research time. Since 2009, in-season testing has been banned, with the preseason tests being the only time for teams to study their car on track. Nothing can beat real-life testing, but that hasn’t kept teams from doing all they can to get close. Multimillion-dollar wind tunnels test scale models, and supercomputers run computational fluid dynamics simulations to find that extra sliver of downforce.
But even research at the factory has been restricted. Since 2021, F1 teams have been under ruthless scrutineering during aerodynamic testing. Teams only have a set of allocated hours for running in the wind tunnel, with heavy limits to the model size and air speed during testing. Computer processing is tracked and limited. So teams need to make sure those simulated runs are as close as possible to the real thing, and it’s not until cars first hit the track with the aero rakes that they learn just how close they are.
Should the testing data match what’s seen on track, it confirms that teams have made accurate simulations, and can develop the car with confidence. When it’s inaccurate, headaches set in, and teams get to work trying to understand where and why the data’s off target.
Placement is pivotal
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Aero rakes are most frequently seen just behind the front axle, right before the sidepods. This is because at speeds north of 150 miles an hour, the wheels become some of the biggest generators of turbulent, or “dirty” air, and can upset the car’s aerodynamic balance. The aero rake can help find out how much the technical directors have minimized this effect, as designs aim to channel dirty air away from sensitive areas like the car’s floor and rear diffuser.Â
Aero rakes’ location and size can vary greatly, ranging from small, targeted probes checking airflow under the car’s floor to larger arrays with over 500 sensors placed behind the front or rear wheels. The sensors can detect airflow in a 60-degree range — incredibly useful when an F1 car pulling through the corners can have plenty of air coming from different places. Even at high g-forces and speeds, the probes have pinpoint precision, reading airflow with an accuracy of 10 microns (a hundredth of a millimeter). The information they gather is processed and transferred in real time.
A phenomenal tool for discovering how airflow affects the car, but the aero rake does have its downsides. With how complex, fragile, and heavy the rakes can be — the larger ones can weigh over 6 pounds — it’s difficult to measure airflow at race pace. As a result, the arrays are almost exclusively used in installation laps during test sessions, and are usually removed before laps are being turned at full song.