F1 wind tunnels: why there's a race for the latest model

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Computer technology continues to advance, with CFD simulations becoming more sophisticated and artificial intelligence now a reality in Formula 1. Yet, traditional wind tunnels remain essential, with several teams building new ones. McLaren's wind tunnel in Woking went into service in October 2023, Aston Martin's is nearing completion, and Red Bull plans to build theirs by 2026. In a detailed analysis previously published, it was shown that ground effect currently causes significant correlation issues with the real world, but a state-of-the-art wind tunnel still offers several advantages.

Size matters
Having ample space is the main added value. Over the years, Formula 1 cars have become longer, wider, and taller, with some teams limited by wind tunnels originally designed for smaller cars. As the scaled model approaches the walls of the simulation chamber, the airflow around the car starts to interact with the walls and ceiling, skewing the results. This problem is exacerbated by the recurring outwash philosophy, with aerodynamics pushing wheel turbulence outward, increasing the risk of interaction with the sidewalls.

McLaren is a prime example of this. The new wind tunnel, inaugurated last October, features a larger simulation chamber, allowing for more accurate vehicle testing with wider steering angles and yaw without the risk of interaction with the walls. These are conditions mainly experienced in medium- to low-speed corners, where the Woking car has made the most significant progress compared to past seasons.

Sensors
Another key aspect is the sensor technology used for data collection. Some sensors can be replaced, upgraded, or added throughout the life of the wind tunnel, but there's more freedom when building a facility from scratch, equipping it with cutting-edge technology. Sensors range from load cells under the central platform, measuring the distribution of forces on the four wheels, to instruments monitoring airspeed, pressure, and turbulence.

It's not just the sensitivity and accuracy of measurements that matter, but also the intrusiveness of the sensors, with the goal of minimizing interference with the airflow. A common technique is PIV (Particle Image Velocimetry), where small solid particles are blown into the tunnel as tracers. These are illuminated by lasers while a camera system takes rapid photos to visualize the flow structure. However, its application is often limited to certain parts of the car due to the high computational demands, a constraint that encourages constant technological upgrades.

The belt
One of the most expensive elements of a wind tunnel is the moving belt under the scale model, responsible for wheel rotation. In the era of ground-effect Formula 1 cars, teams aim to keep the car as close to the ground as possible to maximize the load from the floor, operating at the edge of aerodynamic instability phenomena like porpoising. However, due to the high costs, teams are cautious about letting the model scrape against the belt, fearing damage and thus unable to simulate conditions where the car hits the ground.

This is where the material properties of the wind tunnel belts come into play. With the low pressure created under the car, the belt can experience micro-deformations, which, despite being minimal, are enough to alter the collected data, considering how sensitive ground-effect Formula 1 cars are to small height variations. The 2026 regulations are designed to encourage cars to run higher, but this goal remains to be tested.

Logistics
This aspect is not strictly technical but still affects performance. Teams without their own wind tunnel, like McLaren or Aston Martin in recent years, have incurred higher costs than their competitors, which, under the budget cap, translates into fewer resources for car development. In a 2022 interview, Aston Martin Team Principal Mike Krack commented on the cost of outsourcing wind tunnel work: "Financially, it costs more to buy than to build in-house. So it's a disadvantage, and it's the same for the wind tunnel: we have to prepare our staff, go elsewhere, and do our tests there."

Communication also suffers, which is increasingly crucial in an era where Formula 1 teams exceed two thousand employees. "Team dynamics suffer because people aren't all in the same place," Mike Krack reflected. "Getting the work done isn't a problem, but it is not having the team working together. When there are different locations, there are always losses in between, although unintentional, but it's human nature. During Covid, for example, we all worked on virtual platforms, but then we returned in person because live communication is much more efficient." This explains why McLaren and Aston Martin have invested in building their wind tunnels directly within their headquarters.

The human factor
Technology certainly contributes to the quality of the analyses, but the use of the wind tunnel can't be overlooked. To manage the hours allocated by the FIA to each team, wind tunnel sessions typically last around twenty minutes. It's common to test a setup for a few seconds before moving on to the next one, but even so, there's not enough time to test every possible configuration. It's up to the teams to choose the most relevant tests to perform, based on the technologies available. Investing in a modern, in-house wind tunnel remains an added value in Formula 1, but the final result still depends on the experience of those who will operate it.

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