"Dave Baker" writes in article dated Thu, 27 Oct 2005 10:21:22 +0100:

Tom Miller wrote in message
...
They frightened hell out of me. The rotor weighed
about 100 Kg and spun at 300 rpm. . They used an
eddy current drive to get it up to speed. It took
over an hour to get to operating speed from cold
start.

I did a "back of an envelope' calculation with
regard to the stored energy in one of these
things,and avoided them like the plague ever
since.

Tom Miller

That's a lot less energy than an average IC engine spinning at 6k rpm so I'm
not sure what you are so frightened about.
--
Dave Baker

Tom didn't give us enough numbers to calculate energy. The energy of a
spinning hollow cylinder is (1/2)*mass*(radius*angular_velocity)^2. What
was the radius of the rotor, Tom?

The mass of the moving parts in a car engine is much less than 100kg, and
the radii are probably also much less -- radius of the crank and cam, and
half the stroke length for the pistons, which is a high-ball estimate
because the pistons only move at (radius*angular_velocity) in the middle of
their stroke.

-- spud_demon -at- thundermaker.net
The above may not (yet) represent the opinions of my employer.