The FIA and ACO are continuing their campaign to introduce a class of hydrogen vehicles at the 24 Hours of Le Mans in 2026. The MissionH24 project has been carrying out the technical development of the technology for years, working first on the LMPH2G prototype and then on the H24. However, the current car will soon be retired, with the third generation car that will debut on the track in 2025. The new prototype was created for accelerate performance developmentafter years in which the researchers mainly dedicated themselves to other aspects of the technical feasibility of the project, above all safety.
The hydrogen apparatus
The third generation car marks a step forward in performance from every point of view compared to the previous H24, starting with the fuel cells. The fuel cell is where the chemical reaction of recombination of hydrogen with oxygen takes place, producing water vapour, heat and electrical energy useful for powering the engine. The cells, supplied by Symbio, adopt the new multi stack technology, guaranteeing a 50% increase in power per unit volume compared to H24. The net power delivered is in the order of 300 kW, equivalent to approximately 400 horsepower. The parties involved also speak of progress regarding mass and weight distribution, approaching the typical standards of a racing car.
On board the car, the hydrogen is placed in two tanks made of Plastic Omnium composite material, arranged longitudinally at the rear. Their overall storage capacity is 7.8 kg of hydrogen at 700 bar pressure. According to estimates, the stored quantity corresponds to an autonomy of between 25 and 30 minutes, which at Le Mans translates into stints of 7-8 laps. The weight of the double tank, however, is 100 kg, approved according to international safety standards ECE R134. As for hydrogen top-ups, the development of the refueling infrastructure at Le Mans is entrusted to ACO and TotalEnergies.
Hybrid powertrain
No fuel cell car is purely hydrogen powered, given the inability of fuel cell technology to supply variable power. The fuel cell provides constant power supported by a battery in the role of power buffer, i.e. to satisfy the power peaks required from the pedal. On the new generation prototype, the lithium ion battery can support power of 400 kW, for a weight of 80 kg compared to the previous 92 kg of H24. No kWh capacity numbers were released, although these take a backseat. In fact, the battery does not constitute the primary energy source, but is limited to the role of power buffer, which is why development aims to optimize its power density rather than its autonomy.
The combined power of the fuel cell and battery flows into thesingle electric motor at the rear, against the two of the previous generation. MissionH24 talks about a peak power of 650 kW as the target, equivalent to approximately 870 horsepower, with a weight limited to 30 kg, 18 less than the old configuration. The electric motor represents a step forward from the point of view of specific power, rising to 20 kW/kg. This is a value higher than the 16 kW/kg of the current Formula 1 electric motors and not far from the 22 kW/kg that will be achieved with the 2026 regulations. The electric motor in any case is coupled to a single-speed transmission and a differential limited slip.
As with previous cars, the supporting structure remains an LMP-style chassis developed by ADESS. A distinctive feature is the narrower cockpit, to the advantage of weight distribution, but above all freeing up space at the sides, which can be exploited for aerodynamic and cooling purposes. The goal for the total weight is 1300 kg, 170 kg more than the Hypercars which however have to pay for the additional weight of the fuel. In the press release there are no references to Oreca and Red Bull Advanced Technologies, which in July 2022 were selected as partners for the development of the chassis of the new hydrogen class for Le Mans.
Performance
The target maximum power of 650 kW is higher than the 520 kW allowed by the Hypercar regulations. However, what was declared by the MissionH24 project refers to the peak power, which on an electric-hydrogen hybrid powertrain does not coincide with that which can be exploited for a prolonged period of time. The parties involved talk about performance targets in line with the GT3, which means power in the order of 500 horsepower and a weight of around 1300 kg, as actually declared. Finally, the expected maximum speed is 320 km/h. It is worth remembering, however, that at the last joint annual conference the FIA and ACO aspired to a hydrogen class capable of competing for overall victory.
The points on the agenda
The third generation prototype currently only exists in rendering form, although the various phases of research, development and testing of the power unit components have been completed. It is expected that the design phase can be completed in March 2024, so as to be exhibited a mock-up at the next edition of the 24 Hours of Le Mans. Bench tests of the power unit will begin in October, while final assembly and the start of track tests is set for January 2025.
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