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New generation GKN Hybrid Power flywheel hybrid system for Audi R18 e-tron

Among its many other changes, the hybrid Audi R18 e-tron quattro that placed third at the Le Mans 24 Hours this past weekend featured a new generation of the Gyrodrive flywheel hybrid energy storage system, developed by GKN in collaboration with Audi Sport. (Earlier post.) Audi driver André Lotterer set a new record lap time of 3m 17.47s with GKN’s technology on board.

GKN increased the energy storage capacity and average power rating while retaining the same dimensions and mass, enabling Audi to compete this year in the 4-megajoule of hybrid energy category. GKN said the technology advances embodied in the new flywheel hybrid system will accelerate its work to scale the technology into a lower-cost alternative to battery hybrids for transport applications.


GKN Hybrid Power’s Gyrodrive electric flywheel technology is a Kinetic Energy Recovery System (KERS), harvesting the energy normally lost as heat during braking. The flywheel stores the energy and returns it to the wheels on demand, boosting power, saving fuel and reducing emissions.

When the driver brakes, a traction motor on one of the axles slows the vehicle, generating electricity at the same time. This electricity is used to charge the flywheel, spinning it at up to 36,000 rpm. When the driver accelerates, the system works in reverse. The energy is drawn from the flywheel and converted back into electricity to power the traction motor. This reduces the work done by the internal combustion engine, improving fuel economy by up to 25%, depending on the application.

The core of the hybrid system is the Magnetically Loaded Composite rota, which provides efficient electrical energy storage both cheaper and lighter than batteries. Through motorsport development, Hybrid Power has developed a system that can deliver high, continuously cycling power output over an extended operating life (more than 1 million cycles).

In the R18 e-tron, GKN’s energy storage system sits in the cockpit alongside the driver, delivering up to 4 megajoules of energy per lap and storing up to 750 kilojoules at any time. On acceleration, Gyrodrive feeds the energy back to the front axle where it produces more than 200 kW of power.

The advances in GKN’s energy storage system enabled Audi Sport to move up to the 4 megajoule category and to unlock more of the enormous potential for hybrid sports cars in endurance motorsport. The fierce competitive pressure of Le Mans produces technological advances that significantly improve lap times while also reducing fuel consumption.

—Jörg Zander, Audi Sport’s Head of Engineering

GKN is currently supplying the Gyrodrive system to bus manufacturer Alexander Dennis and transport operator Go-Ahead Group. The company is scaling up production as part of plans to offer the technology worldwide as a viable alternative to battery hybrids.

Our work with Audi Sport is driving forward the development of our flywheel energy storage technology. Gyrodrive’s specific performance, in terms of power and storage capacity per unit mass, has moved on another significant step. These advances help to consolidate and strengthen the lead Gyrodrive has over the competition. Now with four Le Mans victories and hundreds of thousands of miles of on-road trials behind our technology, GKN has the winning solution for companies that want a reliable, high-performance alternative to battery hybrids.

—Gordon Day, GKN Hybrid Power’s General Manager



That's good progress and I think flywheels are a great alternative for hybrids. But they got destroyed by the 8MJ Porsches coming out of the corners and trying to accelerate back to top speed. And they can't really get the flywheels up to the 8MJ category and have them fit for the cars. Meanwhile, the Porsche team went from 6MJ to 8MJ and actually reduced the weight of the system....and will probably be able to do the same next year.
For racing, the flywheel has hit it's limits.

David Freeman

@DaveD, I disagree. The 4MJ flywheel is running at 36,000rpm, and 60,000rpm should be achievable. That would allow them to more than double the energy available in the flywheel to >8MJ. I wonder why they haven't done so yet? They may be limited by the armoring necessary to keep the driver safe if the flywheel disintegrates.


The word around the WEC paddock is they expect Audi to switch to batteries when they go for the 8MJ.

We'll see :)


Of course an 8MJ flywheel is possible. But, it is about the whole package. Audi would have to develop a new engine as well to take full advantage of this. Perhaps they were gambling on that they could still win with this concept. It should also be noted that, in general, the rules favour gasoline engines. Even with this handicap, the car is still competitive, since they set a new record lap time.


They set 3 new record lap times! But that is because they made a huge step forward in aero package at Spa. It surprised even them and now they've decided to keep that package for all the WEC season even though it was only meant to be a Le Mans package initially for low drag. Before that aero came out, Porsche was beating them with top end speed.

But even after the aero change, Porsche leaves them standing on acceleration...but we'd expect that with 8MJ compared to 4MJ of electric energy to throw at the problem.

And yes, I'm surprised at how WEC favors petrol over diesel considering it's a European based sport first and foremost. I'm not complaining, just surprised.

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