How Does An F1 Wind Tunnel Work?
The F1 wind tunnel is a crucial aspect of car development as teams look to balance aerodynamics with power. Aerodynamics is really important in FORMULA 1 as more downforce gives the car grip in corners, while less drag allows the car to go faster on the straight.
One of the main tools for developing the aerodynamics of the car is the F1 wind tunnel.
How does an F1 wind tunnel work?
F1 teams use the wind tunnel to check whether ideas that look good in computer simulations actually work, and to analyze the effectiveness of the different concepts, components, and upgrades.
In real life, as the car goes along the track, it moves through the air. In the wind tunnel, this is flipped around. The model of the car is fixed and air moves over it, essentially by blowing wind with a large fan.
Wind tunnels were originally developed for the aircraft industry and have been used in Formula One for 50 years.
Over time, Formula One wind tunnels have evolved, becoming even more specialized. One of the biggest differences between the tunnels using aerospace and those in motorsport is the F1 wind tunnel has moving ground.
This is essentially a very fast conveyor belt that travels at the same speed as the wind, simulating, in effect, the relative flow between the road and the car.
Whereas the real chassis is made from carbon, the centre of the wind tunnel model is a solid aluminium structure called the spine, with various components bolted onto it. This allows engineers to easily change one area of the car without affecting others.
Most of the parts on the F1 wind tunnel model are made using rapid prototyping and 3D printing, and components like the wings are made of metal.
The model is packed with sensors and analysts then use different high-tech methods to gather data. They can also change the right height and attitude of the model during the test to simulate how the car changes and navigates its way around the track.
One run in the tunnel results in a huge amount of data to analyze. It all helps teams to build a picture of what the flow is doing and decide if a concept or upgrade can progress to the track.
The Mercedes wind tunnel has been designed to take a full-scale car, and this has been done in the past, but the rule makers were concerned this is too expensive, so now teams are limited to using 60% scale models.
There are also other restrictions that have been introduced to reduce costs. Teams are only allowed to use one wind tunnel, and they can’t run the tunnel faster than 180 kph, which is a little over 110 miles an hour.
This may sound quick, but it limits their ability to completely simulate what happens on the track.
There are also restrictions on how many tests each team can perform. These restrictions have been in place for a few years, but further limitations have been introduced for the 2021 season.
The number of runs a team can perform now depends on their position in the Constructors’ Championship.
The last-place team gets 25% more runs than the first-place team, and there is a sliding scale for the teams in between.
The restrictions will be even tougher in 2022, as the FIA try to bring the performance of the class closer together. These tougher restrictions have put pressure on engineers to make sure they get the best out of each run, forcing them to adapt the way they work.
In addition, the tunnel itself has a few interesting aspects:
- The testing area, consisting of a stand on which the car is positioned to measure wind lift or downforce. This is the narrowest point in the tunnel, forcing the air to gather momentum and power just before washing over the car.
- The drive area, where the wind passes through the fan.
- The diffuser, a section of the tunnel that gradually widens, helps slow air so it can be directed more easily.
- The settling area, located prior to the testing area, consists of a honeycombed mesh that directs flow in a straight, predictable path.
- The breather and/or chiller unit sits within the loop in order to prevent a surge in air pressure when air moves.
There are several parts to the testing area as well:
- The two long arms that hold the car in place.
- Under the car, a rolling road can be used to match the wind speed and prevent the air from sticking to the road and thus misleading the sensors.
- The car itself, which can only be 60 percent as big as a regular F1 car.
What are the advantages of wind tunnel testing for cars?
Aerodynamics have historically been developed using scale models, and that will remain the case for a while.
CFD improves all the time, but it cannot yet replace wind tunnel tests, although the aim of F1 is to stop wind tunnel testing by 2030. Currently only two of the 10 teams want to retain wind tunnels beyond this point. Mercedes is on, and Red Bull are believed to be the other.
To develop their aerodynamics, all leading F1 teams currently use scale model wind tunnel programs.
The advantages of scale model wind tunnel testing are numerous…
– There can be an excellent correlation between model results and actual performance on the track. An accurate wind tunnel model, intelligent testing, and an accurate scale model are necessary for this.
– Accuracy. Top level tunnels and models usually measure model forces to within 0.1% of the total forces.
– Speed of development. During a typical 15-minute run in a high-spec wind tunnel used by an F1 team, up to 25 car attitudes can be simulated. As a result of those car attitude points, a full range of aerodynamic data will be generated. The measured data ( forces and pressures ) will be available instantaneously and will provide a comprehensive study of the aerodynamic performance of the vehicle.
– Flexibility of testing. Wind tunnel programs enable aerodynamicists to respond quickly to results and adapt the testing program accordingly. In some cases, these changes will be as simple as quick adjustments to the model, while in others they will involve the addition of work, or the subtraction of work. Due to this flexibility, the process is extremely efficient.
– Test parts are much cheaper, and they can be designed and fabricated much faster than full-scale testing. Scale model testing can also be much more cost effective.
How much does a F1 wind tunnel cost?
Formula 1 teams invest approximately $60-100 million to build their own wind tunnels at their factory to develop the aerodynamics of their cars.
Tunnels that are more sophisticated and expensive typically use one large fan. Due to the bigger fan blades used, turbulence is reduced, but it can still be extremely turbulent. As a result, such measurements are not 100% accurate for determining the flow rate. McLaren have a 145 meter long tunnel, which is shaped like a rectangular circuit, is powered by a giant fan that has a diameter of four meters and rotates at 600 rpm.
F1 teams ran their tunnel all day, every single day before 2009 restrictions were imposed.
Using computational fluid dynamics, or CFD, teams are able to reduce wind tunnel time, as a computer program can tell engineers how their vehicle will perform based on its dimensions. The software is always evolving, and is considerably cheaper tham running physical tests in a wind tunnel that requires a lot more work, money, and space.
How much wind tunnel time do F1 teams get?
With the introduction of the cost cap for the 2021 Formula 1 season, the default allowance will be reduced by more than 30% to only 40 runs per week.
In addition, for the very first time, each team’s allowance of wind tunnel and computational fluid dynamics testing time was determined by their on-track performance.
Mercedes received 90% of the testing allocation for 2021, which equates to 36 runs per week (just under half of what they received for the 2020 season). As you move down the grid in championship order, the allocation increases.
At the other end of the scale, Williams in 10th had a significantly higher allowance of 112.5% or 45 runs per week when developing their 2021 challenger.
The allocations will be reduced for all teams except the 9th- and 10th-placed ones from 2022. The top team will receive 70%, which means that their allocation will drop to 28 runs per week. While the ninth-placed team receives the same allocation as the previous year, the tenth-place team will see their allocation increase by one run to 46.
In the past, aerodynamic development was unrestricted. As a result, several teams operated their wind tunnels around the clock. There were even teams that ran more than one wind tunnel.
How F1 Wind Tunnels Work
This video from Chain Bear shows you exactly how an F1 wind tunnel works.