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Magnetically-Loaded Composite Flywheel System Performs Well in Nürburgring 24hr Race

Williams Hybrid Power’s novel flywheel technology helped to power the Porsche 911 GT3 R Hybrid to the lead for eight hours at last weekend’s Nürburgring 24hr race. The Manthey Racing-prepared Porsche 911 GT3 R Hybrid, which uses WHP’s magnetically-loaded composite flywheel system (earlier post), led the race in the last third of the marathon event, taking the lead at 22:57 hrs on Saturday night.

“The hybrid system worked like a dream.”
—driver Richard Liet

The four-man squad of Jörg Bergmeister, Richard Lietz, Marco Holzer & Martin Ragginger maintained position at the front of the field for eight hours until engine problems prematurely curtailed their impressive performance one hour and a quarter from the finish line. The 911 GT3 R Hybrid was one of 33 Porsches to take the start line in a field of 200 entries in the endurance race on the Nordschleife.

According to Porsche, the 911 with its innovative drive concept, was able to gradually extend its lead through the high efficiency of its hybrid technology and its fuel consumption advantage. The hybrid car needed to pit every ten laps to refuel, whereas its rivals were forced to stop approximately every eight laps.

We are all naturally disappointed for Porsche that their enormous efforts did not result in a landmark victory on Sunday. However, I think everyone recognizes that their courageous and intelligent pursuit of new technologies which save fuel and reduce emissions have been validated in one of the most challenging racing environments possible. We are also delighted that Williams Hybrid Power’s magnetically-loaded composite flywheel system, used in the Porsche 911 GT3 Hybrid, not only stood up to the ardours of a 24hr race, but also that the added performance and fuel-saving brought a real competitive edge to the car, taking it to the cusp of what might have been a remarkable victory for this new automotive technology.

—Williams Hybrid Power’s Managing Director, Ian Foley

It wasn’t enough for a win, but the Porsche hybrid technology clearly proved its potential at one of the world’s toughest races. We will continue developing this innovative drive concept. That was certainly not the last race for a Porsche hybrid car.

—Chairman of the Board at Porsche AG, Michael Macht

Williams Hybrid Power’s (WHP) patented magnetically loaded composite (MLC) flywheel technology, originally developed for Formula One, captures and stores a vehicle’s kinetic energy in a high-momentum composite flywheel. This energy can be re-introduced into the driveline to save fuel, or bolster performance, both crucial variables in endurance racing with clear applicability to road car application


Among its many development programs with Porsche and other clients, WHP is also part of a consortium working together with companies such as Ricardo and Jaguar Land Rover who are seeking to develop hybrid flywheel applications at sufficiently low cost to facilitate mass uptake in the road car market. The purpose of the project is to refine technologies that can provide a considerable reduction in emissions from road cars.



Can someone please provide me with a plate of humble pie please? It could be my dinnertime....


LOL What did you predict Clett? I missed it.


You can read what he said here;


What Clett didn't bother to calculate is basic physics:

L = ωI
E = ½Iω²

At 40 krpm, L doesn't have to be all that big to store plenty of energy.


Pardon the garbage, GCC hasn't been correctly handling ampersand escapes for special characters for the last few months.


At 40k rpm, L would be > 3,000 kgm2s-1. That should surely make the car feel at least odd to drive over crests or kerbs!


(Incidentally, a commercial anti-rolling gyro of 2,500 Nms is enough to stop a 20 ton boat from rolling ).

Henry Gibson

Very nice to see a flywheel used for high power bursts. Where are the supercapacitors?? ..HG..

Henry Gibson

Perfect demonstration of how much improvement can be had with a very limited amount of energy storage, but the UPS hydraulic hybrid showed this already.

Electric motors are very good for moving cars, but Artemis demonstrated that hydraulic motors are good too. ..HG..


Okay, let's go over the numbers for real. I'm using scientific notation for all figures.

omega = 4.0e4 rev/min = 4190/s

E = 400 kJ = 1/2 I omega^2

I = 400 kJ * 2 / omega ^2 = 0.0456 kg-m^2

L = I omega = 191 kg-m^2/s

In other words, if you mounted the flywheel horizontally, drove it at max speed and turned a full circle in 10 seconds, you'd have to apply a torque of 120 N-m to precess it. 120 N-m over the wheelbase of a car is precious little.

Of course, nobody would mount the axis horizontally. A vertical-axis flywheel would have much smaller changes in orientation and lower torques.


OK, here's how I got my numbers. I worked it out as a thick walled cylindrical tube (not as a cylinder), so the moment of inertia, I = 1/2 m (r1^2 + r2^2), where r1 is the inner radius and r2 is the outer radius.

I then assumed mass 30 kg, r1 10 cm and r2 20 cm (some estimates based on the diagrams shown). That gives I = 0.75 kgm^2.

We both agree that L = I omega, so I calculated omega to be 4,188 radians per second (equivalent to 40 k rpm).

That gives L = 3,141 kgm2s-1 by my calculations. I'm not sure where you got the 400 kJ to base your calculations on, although I see the earlier article cited 120 kW for 8 seconds (960 kJ). This is probably just the proportion that they extract.

Incidentally, my concern was that a vertical axis flywheel would prevent proper cresting and kerbing, not direction change.


I got the 400 kJ from a page about the race and the energy-storage limitations (not sure if those were the final rules or not). You're figuring more than 15 times as much energy. Of course, vertical orientation of the flywheel and soft mounts would obviate most of that issue even using your numbers.

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