Halo Around the Head Protects Formula One Driver in Fiery Crash

Grosjean never needed the halo safety device—until he crashed headlong into a barrier at 137 mph.

Crash and burn. Romain Grosjean and his Haas VF-20 on the first lap of the Formula One World Championship in Bahrain. (Image and caption from www.xpbimages.com, copyright Batchelor/XPB Images.)

Crash and burn. Romain Grosjean and his Haas VF-20 on the first lap of the Formula One World Championship in Bahrain. (Image and caption from www.xpbimages.com, copyright Batchelor/XPB Images.)

Despite safety measures being drastically improved over the last few decades, motor racing is still a dangerous sport. This was brought into sharp focus in a shocking incident last November. But, thanks to precision engineering and testing programs, as well as quick reaction times, a driver’s life was saved.

On the first lap of the Bahrain Grand Prix on Sunday, November 29, 2020, Romain Grosjean appeared to clip another car in his blind spot and crashed into a crash barrier at the side of the circuit. Grosjean was in a specially constructed “survivor cage” built into race cars and had a full tank of gas. The car split into two, with the front of the car piercing through the barrier and bursting into flames while the heavier rear of the vehicle went its own way. The Kevlar encased gas tank was likely to have ruptured from the high-speed impact. 

It was the most horrifying accident in Formula One (F1) in a long time. The last time an F1 car split in two was at Monaco in 1991. The last time one caught fire in a crash was at Imola in 1989. The last time accidents occurred in which cars pierced through crash barriers like this were at New York state’s Watkins Glen in 1973 and 1974. Drivers Francois Cevert and Helmut Koinigg did not survive.

Grosjean’s speed on impact into the barrier—with the top of it being the same height as his head—was around 137 mph, according to FIA (Fédération Internationale de l’Automobile) race director, Michael Masi. Grosjean, fully conscious, extracted himself in around 30 seconds as track marshals doused the flames. He suffered burns on both of his hands but broke no bones. 

That Grosjean not only survived the impact but also had relatively minor injuries is a testament to the leaps and bounds in safety improvements that the FIA has made in the last few decades.

The most recent incident in which an F1 driver lost his life was at the Japanese Grand Prix at Suzuka in 2014, where Jules Bianchi, another French driver, succumbed to head trauma after crashing into a truck that was recovering another damaged race car. This led to the development of the halo, a wishbone-shaped device that is designed to protect the driver’s head and was introduced to most open-cockpit race car designs in 2018 after four years of design and testing.

The halo device on a Ferrari SF71H driven by Kimi Räikkönen during preseason testing in February 2018. (Picture and caption courtesy of Wikipedia.)

The halo device on a Ferrari SF71H driven by Kimi Räikkönen during preseason testing in February 2018. (Picture and caption courtesy of Wikipedia.)

The halo device caused a lot of controversy with both fans and drivers—even Grosjean himself. Fans said the device was “ugly” and that they could not identify the drivers as the halo obscured their helmets. Grosjean himself initially opposed the halo, saying upon his 2017 appointment to the Grand Prix Drivers’ Association (GPDA): “We race drivers don’t always hold the same opinion but we are united in wanting the best for our sport.” 

Perhaps the greatest of all time, 2020 F1 World Champion Lewis Hamilton, tweeted after the Grosjean crash, “His car, the cockpit, I don’t know what Gs he pulled, but I’m just so grateful that the halo worked. I’m grateful the barrier didn’t slice his head off. It could have been so much worse.”

In a video message from his hospital bed on the night of his crash, Grosjean recanted his opposition to the halo. “I wasn’t for the halo some years ago, but I think it’s the greatest thing that we brought to Formula 1. Without it I wouldn’t be able to speak to you today.”

UK-based SS Tube Technology (SSTT) is one of three companies in the world that manufactures the halo head protection device. SSTT was set up 20 years ago and has its roots in the fabrication of motorsport exhaust systems. Upon hearing of the FIA’s intention to introduce halos onto open cockpit cars in 2017, Nick Henry, engineering director at SSTT, took an educated guess at what might be the email address of then FIA director and safety delegate, Charlie Whiting, and introduced himself and what his company could do.

“He replied much quicker than I thought,” Henry said. “We managed to get a meeting with him and Andy Mellor, who was heading up the project at the FIA, in Charlie Whiting’s office at the British Grand Prix that year.”

The decision was made to introduce the halo after the rival Aeroscreen system was rejected by F1 driver Sebastian Vettel, who tested it, on the grounds that it distorted his vision and made him feel sick. The FIA was impressed with SSTT’s capabilities and in August 2017 approved the production of 120 of the devices to be supplied by SSTT, Germany’s CP Autosport and Italy’s V System for Formula 1, Formula 2 and Formula E for the beginning of their next championships as early as March 2018.

The FIA stipulates the design of the halo, from the materials it is made from (titanium alloy Ti-6AI-4V grade 5) to the overall weight of the full assembly of the device (which must be 13.5 kg ± 0.5 kg), as well as a host of dimensions and tolerances as set out in the FIA’s Supplementary Technical Information Document. The three halo manufacturers are not allowed to make any modifications to the device without the approval of the FIA.

SST Technology’s Titanium Driver Protection System. (Picture courtesy of SST Technology.)

SST Technology’s Titanium Driver Protection System. (Picture courtesy of SST Technology.)

“The halos are made up of four key components,” Henry explained. “There’s the central pylon, which is the part that mounts to the monocoque ahead of the driver, then the V-transition, the V-shaped section above the driver’s head that connects the central pylon to the main hoop, then there’s two tubes that are each bent to 90° and welded together to create the 180° main hoop. These tubes that make up the main hoop start as a billet and are gun drilled and machined into a tube.”

The reason for machining a billet rather than simply sourcing premade tubing is that grade 5 titanium drawn tube is very hard to make and source within the lead times that SSTT needed. Also, the FIA’s dimensional tolerances are very exacting and unlikely to have been met with drawn, bent or welded tube. Machining allowed SSTT to have better control of the halo’s dimensions.

Henry added, “The tolerances were extremely tight between the mounting points, ±0.1mm; there was also a weight tolerance that was critical and, obviously, tolerances on the ID/OD (inside/outside diameter) of the tubes. That was quite a challenge. It took a final machining step to hit those tolerances.”

Aside from the tolerances, Henry says that the time frames and tube bending were also challenging because grade 5 titanium has high strength and low ductility and exhibits quite a bit of spring back. “It has to be bent very slowly, as there’s a strain rate factor to bend it successfully,” he continued. “Also, the V-Transition is very complicated. It is a challenging part to machine. It’s a very expensive lump of titanium to start with so you don’t want to get it wrong. It takes around 30 to 40 hours of machining time for each part.”

The halo device is then tested by the Cranfield Impact Centre (CIC), a spinoff company from Cranfield University in the UK and one of only two FIA-approved test centers in the world that has been working with the FIA since the mid-1980s to test crash structures, including nose cones, rear crash structures, steering columns and bulkheads.

In 2016 the CIC was asked to build a rig to stress test the halo device. The FIA dictated the dimensions of the rig, as well as where and how the halo device would be attached to it, and the diameter of the pad (150 mm) that transmits the force onto the device by the single cylindrical ram (within 5 mm of the specified loading position).

James Watson, engineering manager at CIC, explained: “We conduct two static tests on the halo, a frontal and a side test where we apply a force of 125 kN (28,100 lbf)—the equivalent of five SUVs resting on the device—using a hydraulic hand pump, hold it for 30 seconds and then drop off.”

During these tests, deformation of the halo structure while it is under load must be no more than 17.5 mm and just 3 mm after the load has been removed for one minute.

Where the halo mounts to the chassis behind the driver’s head and in front of the cockpit, there are fittings that are also machined from grade 5 titanium, welded onto the halo and bolted and doweled into the chassis by the F1 teams. The teams cover the device with carbon fiber fairings and aerodynamic fittings to minimize aerodynamic drag or for use in steering airflow into the engine air intake or cooling ducts around the halo.

Once the halo is mounted on to the chassis, it is tested by the teams themselves, rather than by the FIA, to prove their mountings are strong enough to withstand the same forces as the halo on its own.

Watson says that one of the things that could be done to improve the testing procedure is to test from more angles. However, he added, “If you’re testing a manufacturing machine, you will know which direction the force is going to come from, so you know where to provide the load. You cannot predict a crash; it could come from any direction.” 

“You could work from statistics to try to get the most likely crash angle, you could do multiple tests. But then, is it cheaper to do it by computer simulation? Is it worth the time, and also how accurate is it? You still need physical testing to get a validated model. The ultimate proof is the physical test. You can’t argue with the results of physical tests.”

When asked how integral the halo device was to Grosjean’s survival, Henry said: “I think there’s no doubt it played a part in saving his life. Without the halo his head would have been the first thing to hit the barrier. I think the halo definitely proved its worth there. Also, all the other things like the nose cone, the monocoque, then the halo, the HANS device, the crash helmet, the collapsible steering column, the fireproof overalls; I think every one of those did what it was designed to do. The way you can see that the halo peeled apart the barrier, along with the nose cone, was perhaps one of the more visible benefits, but every everything worked together.”

Watson agrees: “Had the halo not been there you don’t know what would have happened, the whole kinematics of the car would have been different, you just don’t know.”

“People were criticising the way the barrier deformed, but at least it absorbed some of the energy; it didn’t spring back and push the driver back onto the track, which could have made it a lot worse.”

Coincidentally, Watson says that for the 2022 season, the FIA had already increased the forces applied for future tests to further protect drivers in higher speed impacts: “In 2022 there’s an increase in energy required for nose cones to absorb more energy. At the moment, it’s at 90 kilojoules, but for 2022 it’s expected to go up to about 130 kilojoules, which was planned before the Grosjean accident.”