John's Journal: John McElroy's multimedia blog about the automotive industry

Driving a Flywheel Car

May 8th, 2008 at 2:38pm

Small Flywheel Housing

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 . . .

Small Ford Pinto He showed me a Ford Pinto with a flywheel that was packaged into the back seat area. A lot of people laugh when I mention that it was a Pinto, but let me tell you, this thing was impressive.

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.

The Flash Player is required to watch Autoline. Download Flash.

Runtime: 5:18

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.Small Flywheel

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.

15 Comments to “Driving a Flywheel Car”

  1. Claus Segebarth Says:

    Very interesting. Of course, one would like to see flywheels installed in ‘run-of-the-mill’ cars for the general public – and at prices the general public can afford. When will the auto industry finally wake up?

  2. DaveT Says:

    John,
    Very interesting that Andy Frank was the father of the Flybrid.. he also is known as the father of the PHEV. :-)

  3. Mike Says:

    Aside from the unusual management timidity or conspiracy theories, the safety issues surrounding flywheel energy storage may explain the abandonment of this technology. What happens when one of these cars blows a tire or otherwise gets out of control?
    Ten years ago at the L.A. Auto Show at least two big US auto companies had flywheel demonstrators.
    Now, it’s ‘nothing to see here’.

  4. Jack Says:

    You aint seen nuttin yet. More coming soon

  5. Mike Kane Says:

    “About three years ago someone parked a flywheel car at an airport – and after seven days. . .” Any idea of who actually created that vehicle? I thought it was some computer company CEO. . .not certain. . .would like some details if you have any information.
    Thanks,

    M. Kane

  6. Bob Church Says:

    The biggest problem with the major auto makers is that they have so much money tied up in the current propulsion systems that to venture into anything new would prove to costly. There is an alternative energy storage system but none are interested, modification of the flywheel system is all that is required.

  7. TERRY Says:

    Funny, I just read an old 1996 Discover mag. Talking about a flywheel car….

  8. Andrew Says:

    Why not a flywheel car? Because flywheels for a hybrid drive would be storing so much kinetic energy. If the flywheel contains enough power to move a car forward, it contains enough energy to move itself forward with a momentum equal to your car going at 60 miles an hour, which for the relatively lighter flywheel could be well over 200 mph. Granted, it will need to smash through whatever containment cylinder exists but that just means more debris is created.

    Batteries have the advantage of only releasing potential energy when the circuit is closed, with exceptions such as accidental short circuits (fires), and even there it is not as dangerous as a flywheel. You have some time to react to the conversion of the potential energy to kinetic in a lithium ion battery (you notice smoke and get out before being burned alive).

  9. bananabender Says:

    It is absurd to say that flywheels are intrinsically dangerous. Every single internal combustion car in the world already has one. When did you last hear of anyone being killed by an exploding car flywheel?

    The problem is trying to build extremely light composite flywheels rotating at extremely high speeds. However a heavy machines steel flywheel rotating at up to 20,000rpm is quite easy to build. It isn’t going to disintegrate.

  10. Bill Says:

    I don’t see how this could work. What about the angular momentum of the flywheel? How could the car turn a corner (or go up or down a steep hill, depending on the flywheel’s axis of rotation) without the car exhibiting unusual motions?

  11. Frank Says:

    @Bill: This can be easily solved by adding another flywheel with the opposite direction, so their angular momentum sums to 0. The only problem is that their speeds need to be matched.

  12. Jim Robertson Says:

    The purpose of the flywheel needs to be defined. I do not see it as storing enough power to travel long distances and certasinly there is limited value to very rapid acceleration.

    I see the device as an energy balancer for a vehicle that will be starting and stopping continuously. Once we have achieved a “normal” speed we steal back energy to bring the flywheel back to maximum RPM to accelerate after the next stop.

    Keep it simple!

  13. T.C. Gore Says:

    I understand the Swiss powered commuter buses with flywheels not so long ago. They were spun up by regenerative braking, and auxiliary inputs at certain bus stations. Not sure why they were discontinued.

  14. R. W. Lee Says:

    Good article in the Dec 2011 Economist on composite flywheels turning at 60,000 rpm.

  15. RM Says:

    I am not sure how this is bad exactly…

    The flywheel is safe inside a shroud or vacuum, and the fact that a flywheel is already in some cars with no problem indicates the safety concerns may have to do with fixing and working on or near the flywheel, as proximity to it might be hazardous.
    However, I am sure we can create something viable, and engineer a solution for the smaller issues.

    An electric flywheel car would be even cooler!

    After Exxon-Mobile/BP, Chernobyl, and Fukishima catastrophes, I think it would be nice to move away from the older outdated norms of thinking and obtaining energy in safer ways that won’t devastate LOTS of land area and human lives.