Why do F1 cars use paint vis flux and aero rockets in testing?

Why do F1 cars use paint vis flux and aero rockets in testing?

Formula 1 teams use pre-season testing to extract as much data as possible through various methods – including flow visualization paint and aerodynamic flares.

Both play a key role in every pre-season test – plus some free practice sessions in the season – as teams try to learn more about aerodynamic performance.

This year will be no different with the 2024 F1 pre-season test on February 21-23 at the Bahrain International Circuit, which also hosts the opening grand prix of the year on March 2.

Valtteri Bottas, Alfa Romeo C43, with aero paint

Valtteri Bottas, Alfa Romeo C43, with aero paint

Photo by: Mark Sutton / Motorsport Images

What is the running color on an F1 car?

Flow-vis is brightly colored paint spread on the body part of an F1 car used in pre-season testing or free practice sessions.

The paint is formed by mixing a fluorescent powder with what is usually paraffin oil and is applied to a specific part of the car when a driver is set to leave the garage. Flow-vis can be applied to the front wing of a car, its side or even the whole, but it is especially useful when a new body part has been applied.

Some teams may use a fluorescent paint that can only be seen under an ultraviolet light, so rivals cannot see their data, while another way of doing this is by covering the car once it enters the pit. F1 teams must also be careful with the amount of flow applied because too much will cause puddles, while too little makes it difficult to collect valid data.

Flow-vis is used to determine aerodynamic performance because, when a car travels at high speed, the paint moves across the body in accordance with the air flow. This leaves lines as the paint begins to dry, meaning it’s essentially a wind tunnel, but with ‘real world’ air.

Sergio Perez, Red Bull Racing RB19, rear wing detail

Sergio Perez, Red Bull Racing RB19, rear wing detail

Photo by: Mark Sutton

How is F1 flow-vis color analyzed?

The lines left behind are incredibly important because they provide a greater understanding of the car’s real-world surface flow and airflow, meaning teams can very clearly visualize the type of build they have.

So, for example, if flow-vis is applied to the underside of the nose, then lines will usually appear above that showing how the air has reacted to it and the direction the nose causes the air to travel.

Once the car is back in the garage, the aerodynamicists will then take pictures before the flux is wiped away. What is important is that streamlines are usually not visible to the naked eye and can only be analyzed through images.

When it comes to analytics, what teams are primarily looking for is external data, such as where the airflow is divided.

Airflow separation refers to when airflow deviates from the surface of a car and becomes turbulent, leading to increased drag – as a low pressure area is created behind the vehicle – reduced stability and reduced downforce. All of this can be seen through the streamlines and this helps aerodynamicists identify any problems, their cause and how to correct them.

Flow-vis paint is arguably of greater importance in modern F1 as the series imposed a wind tunnel testing restriction for 2021. So flow-vis paint gives teams a chance to test with real air and understand more about how their car moves through the air and where aerodynamic improvements can be made.

McLaren MCL60 details

McLaren MCL60 details

Photo by: Giorgio Piola

What are the aero rockets on an F1 car?

F1 teams also use air rockets throughout the season, which are metal fence-like structures placed on a car during testing. Aero rackets come in different sizes and sometimes it’s not obvious when a team is using one, but the big ones are hard to miss as they are usually placed behind the front axle or near the rear axle.

Aero rockets consist of a series of Kiel probes, which paint a picture of how the airflow exits the car’s body parts such as the front wing or wheels. So, airplane rockets are similar to flow-vis, except they show how the airflow is structured into the car rather than how it exits or around it.

The teams are mainly looking to see how the data collected by the plane’s rockets, which can be done almost instantly, matches what they saw in the wind tunnel.

When a car is driving around the circuit, the team will measure how the metal fence bends due to the force of the air and that is used to calculate the air pressure and speed at different points around it.

Yuki Tsunoda, AlphaTauri AT04

Yuki Tsunoda, AlphaTauri AT04

Photo by: Mark Sutton / Motorsport Images

The data collected from an aerodynamic rocket then helps teams decide on its most optimal aerodynamic configuration, as it helps create a map of the airflow around the car and shows how different configurations affect the car’s performance.

F1 teams are also looking for gaps in the data, so where the flow is separated and where the car isn’t getting the proper flow structures – for example, if the front wing wasn’t generating the downforce it needed.

So without air rockets, F1 teams would find it extremely difficult to judge what the optimum condition for downforce levels is.

Other key terms to know about pre-season testing

A glorious run is when an F1 team from the lower tier records the test time sheet after setting a lap with a lower fuel load or softer tyres. This is usually because other teams, especially those at the top, are trying different set-ups so their lap times aren’t as fast as they could be, so the midfield teams often go for a glorious run just to to boost morale a bit and to see how the car actually is in qualifying specs.

Sandbagging refers to when F1 teams hide their potential in pre-season testing so as not to show their full pace until the opening Grand Prix. F1 teams are sandbagged so as not to draw attention to themselves or, in particular, a new car part, because rivals might notice it and patch it together before the start of the season.

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