May 8th, 2008 at 2:38pm
About 25 years ago I drove a hybrid car that was very different from the hybrids on the road today. This one was powered by a flywheel. Instead of storing energy in a battery and then using that to accelerate the car, it stored energy in the form of a spinning flywheel.You know that kind of toy car where you push it along the carpet to turn the wheels to get an internal flywheel spinning, then let it go and watch it scoot across the floor? It’s pretty much the same idea.
The flywheel hybrid I drove was the brainchild of a professor named Andrew Frank who was then at the University of Wisconsin, though he’s now at UC, Davis. He was modifying different types of vehicles to run on flywheels and I was intrigued to learn how they worked. So I took a road trip to Wisconsin to pay the professor a visit.
More photos plus video after the jump . . .
The car could use the engine or a regenerative braking system to get the flywheel spinning, and then the driver could tap into that power to accelerate the car. As I recall, Professor Frank claimed it could achieve something like a 50 percent improvement in fuel-economy. But I was equally impressed by the performance. This Pinto would burn rubber across the entire parking lot!
In fact, you had to be careful in putting the power down. It had so much torque that it was easy to overpower the car. The Pinto was equipped with a manual transmission and I had to ease out the clutch and wait until it was fully engaged before flooring it. The drivetrain of the Pinto was never built to take that much power, so I didn’t want to break the professor’s pet project.
The idea of using a flywheel is not new. You can easily find information about other flywheel efforts on the web. But the other effort I’m most familiar with dates to the mid-1990s when Chrysler started developing a car called the Patriot to race at Le Mans. It was a hybrid that used a flywheel and their simulations showed that it would be extremely fast and quite fuel efficient.
But flywheels pack an enormous amount of energy, and when they fail, they often shatter with catastrophic results. This video shows a flywheel being tested for durability. I’ve been told that in this test the flywheel is being stopped with 25 G’s of force! You can’t see the flywheel itself though, it’s contained in a safety shroud in case it fails during the test.
There were rumors that a development engineer was killed when the composite flywheel for the Patriot shattered during a test. I never found out if that rumor was true, but soon after it surfaced, Chrysler quickly and quietly shut the program down.
Now the idea is being revived and a flywheel-hybrid, or what’s called a flybrid, will appear on several Formula One cars next year. The organizers for the Le Mans 24 hour race, and the American Le Mans Series are interested in allowing them in 2010.
As automakers around the world race to come up with advanced batteries for hybrid systems, it’s fascinating to see that the flywheel could turn out to be a competitive energy storage device.