Tuesday, March 5, 2024

Inside Spark’s Development of the Upcoming Extreme H Car

The implementation of hydrogen fuel in motorsport is accelerating as Extreme H, an off-road series from the organisers of Extreme E and Formula E, prepares to debut in 2025.

A recent announcement stated plans for Extreme H to become the first hydrogen FIA World Championship in its second season, marking a huge milestone for the use of zero and low-emission technology in racing.

Extreme H will use a new bespoke off-road car, developed with some of the key partners from Extreme E including constructor Spark Racing Technology and battery supplier WAE Technologies.

Several characteristics of the Extreme H vehicle, which is gearing up for its first off-road test later this year, draw on lessons learned from the all-electric Odyssey 21.

“At the beginning, when we started talking about the H car, we thought it would be just an evolution of the E,” Spark motorsport director Pierre Prunin tells Racecar Engineering.

“But we wanted to improve everything.”

Many of those improvements are based on redressing fundamental design elements of the Odyssey 21, such as its two-seater configuration.

According to Prunin, this is a hangover from a preliminary brief that Extreme E events would be held with two people sharing the cockpit: one navigating and the other driving towards checkpoints, Dakar Rally-style.

Spark is developing the Extreme H with central driver positioning, which will probably make passenger rides difficult.

The organisers eventually opted for a standard qualifying and race format where the male and female driver pairings would take turns behind the wheel without a navigation partner.

“That’s why the car has two seats,” says Prunin. “And it explains why we ended up with a non-adjustable seat.”

As a central positioned single-seat car, Spark hopes the Extreme H will address the Odyssey 21’s inherent limitations and open the door to greater adjustability.

“The seat, wheels and pedals are very adjustable,” says Prunin.

“It will have adjustable pedals that will improve massively the comfort, feeling and safety of the drivers because we know how the car will be used [from the start].”

Driver comfort blends into driver safety and the Extreme H car is being developed with standard-setting measures for hydrogen racing in mind.

The championship’s FIA blessing means that the global motorsport body is working hand-in-hand with Extreme H on crash testing and safety features.

This contrasts significantly to Extreme E, where the FIA only became deeply involved after the inaugural 2021 season had got under way.

“We have completely changed the chassis philosophy because we have had to pass some very stringent crash tests from the FIA,” Prunin notes.

“They are from another planet if you compare to what they are on standard cars. It’s actually multiplying by 10 the loads on some chassis components. We had to rethink completely the architecture of the chassis for that purpose.

“We did, and still do, some simulations. We will have to do crash tests which we didn’t have to do for Extreme E because they are considered traditional rally cars and we just had to follow some design rules.

“Here, we have to crash test to prove that we can protect the reservoir and fuel cell adequately. That’s a massive change. It’s a complete chassis change.”

The hydrogen fuel cell for Extreme H will go where the battery was situated in the Odyssey 21 Extreme E car.

The battery layout is another area in which Spark can benefit from having a clean design slate for Extreme H, with the knowledge of how Extreme E panned out.

McLaren Applied Technologies was initially supposed to provide the full electric powertrain for the Odyssey 21, but the deal fell apart and WAE was brought in to quickly develop a bespoke 54 kWh battery. Helix, meanwhile, joined as the spec motor and inverter supplier.

Rather than being a double-layer design like in Extreme E, the battery for the hydrogen car will lie flat underneath the spec hydrogen fuel cell. It is set to be about 1.2 metres long, narrow enough to keep away from the crash structure, and have a cooling plate as its lid.

“The car architecture was defined already,” reflects Prunin. “It was built around a cubical Formula E battery.

“Had we started from scratch, knowing we would do a bespoke battery, it would have been a floor battery for a lower centre of gravity and easing of the packaging elements.

“We have a really vertical motor/gearbox, which is not good for centre of gravity. Having the battery on the floor lowers the centre of gravity.”

Spark is also looking to make the Extreme H car more durable than its predecessor, especially to deal with big jumps. Torque cuts were introduced during the first Extreme E season to ease pressure on the driveshaft after several examples were broken in testing.

Prunin envisages the Extreme H car having around 25 per cent more torque than the Odyssey 21.

“We will also increase the inertia of the car,” he says. “It will stabilise the car over small bumps and jumps.

“Typically, we are going to beef up massively the transmission and driveshaft so that we can reduce the amount of torque cuts that we are doing.

“In this way, we can give a bit more freedom to drivers and they can control the pitch of the car more when they are jumping.

“We take the occasion of a new car to do all the modifications that are too expensive or not reasonable to do when you have an existing car.”

Spark initiated torque cuts upon landing in the first season of Extreme E to ease stress on the driveshaft and related parts.

Due to the Extreme H chassis being in development, an Odyssey 21 was used as a test mule earlier this year to try out some of the nascent hydrogen powertrain components.

Most of the testing so far has taken place virtually and on dyno rigs, except for a few brief runs with the mule in a car park. The first off-road test of the new Extreme H prototype – a huge landmark for the programme – is expected to take place before Christmas.

“Real development work will start at the beginning of next year with heavy running,” says Prunin. “The first six months will be a lot of running and validation for everything.

“The complexity of a hydrogen fuel cell car is huge compared to an electric car.

“I think we are multiplying the complexity by five. It’s actually a hybrid car. It’s both electric and you are adding the hydrogen power. It’s very complex.”

Performance-wise, Spark wants the as-yet-unnamed Extreme H to at least equal its all-electric predecessor, which is designed to produce a top-end power output of 400 kW (around 550 bhp) and can launch from 0-62mph in 4.5 seconds.

Drawing on the lessons learned from the Odyssey 21 project, Spark and Extreme H are laying the foundations for the most significant hydrogen motorsport development to date.

To find out more about the technical evolutions of the Odyssey 21 Extreme E car, check out the November issue of Racecar Engineering magazine. Available soon!

The post Inside Spark’s Development of the Upcoming Extreme H Car appeared first on Racecar Engineering.

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