THE FLYWHEEL CAR

There is much more promise in the Lockheed flywheel bus than meets the eye. First of all, it increases the energetic efficiency by two quantum jumps. One is doubling the overall conversion efficiency from fuel to electric power, as mentioned above. But the second reason is equally important.

In all present road vehicles, braking is achieved by an absurdly crude and wasteful method: The kinetic energy of the vehicle is turned into heat by friction in the brakes, whence it is quite literally thrown into the wind. Not so in a flywheel vehicle. Here braking can be accomplished by reversing the motor generator functions. The wheels of the vehicle to be decelerated drive the motor (now used as a generator), which generates current to turn the flywheel generator (now used as a motor) and this will rev up the flywheel; the generator on the wheel axle is thereby subjected to a heavy load as it delivers a large current, and this will brake the vehicle. Thus, the excess kinetic energy of the vehicle is not turned into useless heat, but into additional kinetic energy of the flywheel. It is like a man returning from a trip who puts his unspent money back into the bank instead of flushing it down the toilet.

But if it's all that simple, why hasn't somebody thought of it long ago? The answer is that only the theory is simple; the main practical obstacle used to be materials. Most metals could not withstand the centrifugal force at the required rotational velocities without flying to pieces. The Lockheed flywheel is made of a specially developed steel alloy and attains an energy density 10 times larger than that of the Oerlikon flywheel. Its profile was optimized by computer and turned out center thick with upturned edges. The Oerlikon flywheel ran in air, and it spent its kinetic energy in minutes; the Lockheed flywheel runs in vacuum, and in a stationary bus, it will run for 8 hours before its velocity drops to 50%.

Brat even the Lockheed flywheel will soon be old hat. "Superflywheels" made of concentric plastic rings with graded mechanical and geometrical properties are now being designed at John Hopkins University and other institutions (for details, see Scientif. American, Dec. 1973). These superflywheels can store some 50 times more energy per unit weight than conventional electric batteries. Magnetic suspension in vacuum canisters would lengthen the no load rundown time to many months.

There are several important fields for this type of energy storage. For automobiles, the system would be similar to that used in the Lockheed bus. However, a spinning flywheel gives rise to special torques, and a flywheel powered car going over the top of a hill might find itself flying like a ski jumper and landing at right angles to the road. To prevent such gyroscopic effects, two counter rotating flywheels on the same axis would add their stored energies, but their gyroscopic effects would cancel.

How about safety? When a spinning metal flywheel goes to pieces, the effect is that of an explosion. But the new plastic fiber materials not only exceed metals in tensile strength, they also disintegrate into harmless shreds when they are overstressed.

Other characteristics of flywheel cars would also be very favorable: weight of the drive system 500 to 600 lbs; a range of 200 miles at 60 mph; acceleration at least as good as with the ICE; and a no load rundown time of 6 to 12 months, which means you could leave the car parked anywhere over the winter with the flywvheel spinning, without starting problems in the spring to drive i to the nearest recuperation point where the flywheel could accept a 30 kWh charge in five minutes (or home, where it could accept this charge from household mains overnight).

Maintenance would be minimal, and the life of the engine would far outlast the life of the body; people immune to the gimmicks of Detroit and Madison Avenue could drive their cars for many hundreds of thousands of miles.