Wednesday, February 21, 2024

How the Formula 1 Halo works

In the world of Formula 1, driver safety is paramount. After the crash of Jules Bianchi at the 2014 Japanese Grand Prix, a new safety device called the ‘Halo’ was introduced to improve driver safety. While its reception was mixed at the time, the controversies revolving around the device have now simmered down.

That’s because the Halo has more than proven its life-saving capabilities over the last few seasons. From Charles Leclerc’s incident at Spa in 2018 to Romain Grosjean’s fiery crash in Bahrain in 2020 and more recently, Guanyu Zhou’s car that flipped upside down at Silverstone in 2021. Many drivers have walked away from serious incidents with only minor injuries thanks to the Halo.

Orange McLaren Formula 1 car landing on top of a white Sauber Formula 1 car at a first corner crash
Fernando Alonso’s McLaren landed on the cockpit of Charles Leclerc’s Sauber at the first corner of the Belgium Grand Prix in 2018. CREDIT: XPB Images

Designed to withstand 15 times the static load of a Formula 1 car and a 20kg (44Ibs) wheel travelling at 225kph (140mph), this article delves into the engineering behind the design, manufacture and testing of this revolutionary safety device.

What is the Halo?

The Halo is a three-pronged tubular titanium structure that surrounds the cockpit of a Formula 1 car. It acts as a shield to deflect or absorb impact forces during accidents. The FIA (Fédération Internationale de l’Automobile) began investigating different frontal protection devices as early as 2011. The governing body explored options such as full canopies and rollbar-like structures.

Three designs emerged as potential solutions:

  • The Halo
  • The Shield – a windscreen made from Opticor plastic
  • The Aeroscreen – a combination of the Halo and the Shield

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Side view of the cockpit of a Red Bull Racing Formula 1 car fitted with a curved aeroscreen
The Aeroscreen concept was tested on a Red Bull in 2016. CREDIT: XPB Images

To determine the effectiveness of these devices, the FIA developed rigorous safety test programmes which involved applying significant vertical, frontal, and lateral loads for five seconds. The Halo was the only device that passed these tests.

The FIA also conducted investigations into past accidents, simulating each scenario with the Halo to evaluate its potential impact on driver safety. The analysis of 21 case studies showed that in 19 instances, the Halo would have reduced the severity of driver injuries.

What is the Halo made of?

Contrary to popular belief, the Halo is not made entirely of carbon fibre. Instead, it is made from a titanium alloy known as Grade 5 6AL4V which is an aerospace-grade material. This allows the three-pronged tubular titanium structure to weigh only 7kg and yet still withstand the weight of two African elephants [1].

There are three main elements to the Halo:

  • Front section at the centre which is called the ‘V transition’
  • Two tube sections that are welded together
  • Rear mounts

Black and red Halo device leaning up against a red garage wall
The Formula 1 Halo can withstand the weight of two African elephants and only weighs 7kg. CREDIT: XPB Images

How is the Halo manufactured?

As non-standard tube sizes were used, manufacturers had to start from scratch. ‘We have to gun drill the bar and then turn the outer diameter before the tube could be bent,’ highlights Daniel Chilcott, Managing Director of SST Technology. ‘Due to the tolerance required between the rear mounts and the main Halo structure, the Halo is actually made from two tube sections that are welded together, not a single piece bent a full 180 degrees.’

Titanium oxidises when heated and so the tubes are bent using a process known as ‘cold bending’. To ensure the titanium maintains its high performance throughout the bending process, the bending speed needs to be slow and consistent.

‘The only reason we are able to do that is because we use a fully electric tube bending machine,’ highlights Chilcott. ‘This applies the same amount of torque throughout the process, achieving a proportional bend, rather than using a hydraulic machine which may not be able to apply a consistent load, leading to breakages.’

Side view of the titanium Halo structure without any livery
SST Technology use a bespoke shroud technique to weld the titanium tubes together

Welding the titanium tubes is also a challenge, as the material must be shielded to prevent oxidation which could affect the weld’s integrity. ‘We have developed a bespoke shroud technique that we weld the parts within using a unique gas mix to ensure that the welds don’t oxidise in any way,’ says Chilcott.

The V transition and rear mounts are machined from titanium billet using 3 and 5-axis milling machines. The complexity and size of the V transition result in a machining time of at least 40 hours. Once the tube sections are welded and cooled, they are attached to the V transition, and the rear mounts are also welded to the structure.

The final step involves machining the whole assembly to tolerance, ensuring it fits the chassis properly. ‘The tolerance across the bolt holes in the rear feet is 100 microns which is a challenge on what is ultimately a fabricated structure. We address that by securing the Halo by the ‘nose’ and finish machine the rear mounts and without this final process, the Halo wouldn’t fit to the chassis,’ explains Chilcott

What safety tests does the Halo have to pass?

Each Halo design must undergo rigorous safety tests as specified by the FIA regulations to become ‘FIA approved’. To do this, the Halo is tested at the Cranfield Impact Centre (CIC), the only facility in the world approved to crash test the Halo.

‘The Halo testing consists of two static tests,’ explains Jim Watson, Engineering Manager at CIC. ‘For the first test, the load comes from above at an angle of 22.5 degrees and that is the more straightforward test to do. The more difficult one is where the load comes in from the side. Both tests reach 125kN and then the load comes off, so we don’t test the ultimate strength of the part, only to the required load specified in the regulations.’

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Once passed, the strength of the structure alone is proved safe. However, the Halo is tested again during the homologation of the chassis. During these tests, the Halo is secured to the chassis and there must be ‘no failure of any part of the survival cell or of any attachment between the structure and the survival cell.’

Does the Halo affect aerodynamics?

‘Aerowise, it’s certainly not penalty free,’ says Peter Prodromou, former Chief Technical Officer of Aerodynamics at McLaren. ‘The challenge in the first instance is to cope with it and minimise the losses and thereafter think about the opportunities because it does open up some avenues that are potentially interesting. There are various implications on how it affects the flow into the engine air intake, into certain cooling ducts that teams have in that area, including ourselves, as well as how it effects cooling onto the rear wing.’

Perspective images of six different types of Halo including Ferrari, Toro Rosso, Mercedes, McLaren, Red Bull and Force India
Teams have tried a number of different designs of fairings and Halo shapes to minimise the impact on the aerodynamics

To compensate for the aerodynamic losses of the Halo, particularly around the airbox, the FIA permitted teams a 20mm area of freedom in which they could develop aerodynamic fairings. To bond these carbon fibre fairings to the Halo, teams wrap the titanium structure in carbon fibre, giving the Halo the same look as the rest of the chassis.

Red Halo with a two tier winglet fairing on the top
When the Halo was first introduced, teams came up with diverse aerodynamic solutions, but teams have now converged towards a one or two-tier winglet-like fairing that sits on top of the main structure. CREDIT: XPB Images

Who has been saved by the Halo?

Since its introduction to F1 in 2018, the Halo has become an integral part of most single-seater motorsport categories including Formula E, F2, F3, Euroformula Open, and Super Formula. With its wide adoption, this revolutionary safety device has saved many lives and prevented drivers from serious injuries.

The Halo’s effectiveness has been demonstrated in several accidents. The first notable incident was during the 2018 Belgium Grand Prix when Fernando Alonso’s car launched over Charles Leclerc’s cockpit. The Halo protected Leclerc, and subsequent analysis estimated that it endured a 56kN load [2], demonstrating its ability to withstand extreme forces and prevent injuries.

During the opening lap of the Belgium Grand Prix in 2020, there was a massive accident involving multiple cars at the Spa-Francorchamps circuit. Giovinazzi’s car made contact with the rear of Russell’s car, causing it to go airborne and flip over. The Halo on Russell’s car deflected the impact of Giovinazzi’s car, preventing it from directly hitting Russell’s head.

The remarkable life-saving capabilities of the Halo were prominently demonstrated during Romain Grosjean’s harrowing crash at the 2020 Bahrain Grand Prix. As his car collided with a barrier at high speed, it split in two and instantly burst into flames. Miraculously, the Halo deflected the barrier and created a protective zone around Grosjean’s head, allowing him to escape with relatively minor injuries. This incident served as a definitive testament to the Halo’s ability to safeguard drivers in the most treacherous circumstances.

The rear of the Haas Formula 1 car with the front embedded in the barriers
The Halo deflected the barrier protecting Grosjean’s head as his Haas crashed into the barrier and split in two at the 2020 Bahrain Grand Prix. CREDIT: XPB Images

The collision between Lewis Hamilton and Max Verstappen during the 2021 Italian Grand Prix initially appeared minor, but a closer analysis revealed the crucial role played by the Halo. The incident occurred at Turn 2 in Monza, causing Verstappen’s car to go airborne and land on top of Hamilton’s roll hoop and Halo. The Halo protected Hamilton’s head, preventing serious head injuries as Verstappen’s rear-right wheel rotated across the Halo and Hamilton’s helmet.

Verstappen’s Red Bull landed on Hamilton’s Mercedes in the gravel of Turn 2 in Monza
The right rear wheel of Verstappen’s Red Bull made contact with Hamilton’s helmet at Monza in 2021. CREDIT: XPB Images

The British Grand Prix in 2022 witnessed a series of dramatic incidents, including a red flag-inducing crash in which Zhou Guanyu’s Alfa Romeo collided with a catch fence. While Zhou escaped unharmed thanks to the Halo, the crash overshadowed a terrifying collision in the Formula 2 support race.

Williams academy driver Roy Nissany aggressively defended his position, resulting in a collision with Dennis Hauger. Hauger’s car ramped off a curb and into Nissany’s cockpit, but both drivers emerged unharmed as the Halo prevented a potential decapitation.

The Halo has become an integral component of driver safety in Formula 1 and represents a collective commitment to prioritising driver safety and taking proactive measures to minimise the risks involved in high-speed racing. Its innovative design, combining lightweight titanium and carbon fibre, along with the stringent manufacturing process ensure its strength and reliability. The Halo has set a new standard for safety in motorsport, ensuring that drivers can push the limits of performance with greater peace of mind.

References

[1] 2018. How to make an F1 Halo [Online]. FIA

[2] 2018. FIA confirms level of impact on Leclerc’s Halo in Spa crash [Online]. Crash.net

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