FlyWheel Battery

> At this velocity the flywheel rim is moving at 21,513 km/h, or Mach
> 17.6. We're now approaching sub-orbital velocity for the flywheel in
> your basement. This is really pushing engineering technology and
> materials science.
>
> I thought a Mach 1 flywheel was more technologically simple to mass
> produce for every household.
>

Some modern flywheels operate in a vacuum with magnetic levitation. No
air, no speed of sound. Thus, the velocities may be right but the mach
numbers are meaningless.

Here's some speed data from the web. Looks like 10- 60,000 rpm is
happening.

Commercial flywheel company (http://www.magma.ca/~fesi/page3.html):

nit Specifications

Power: 1.5 kW 3 PM BLDC

Energy: 250 Wh rotor (rim & hub) 15.5"OD x 2"L 8 kg

Mass: 135 kg (excluding power converter & controller)

Operating Speed: 15,000 rpm to 30,000 rpm

Suspension: mechanical bearings

Unit Specifications

Power: 1.5 kW 3 PM BLDC

Energy: 1.1 kWh rotor (3.5" Series 45 Mk3)

Mass: 65 kg (excluding power converter & controller)

Operating Speed: 15,000 rpm to 45,000 rpm

Suspension: mechanical bearings

From http://www.grc.nasa.gov/WWW/RT2001/7000/7750le.html, research on
magnetic flywheel bearing:

imulations for this unit indicated that the controller should be robust
up to its top operating speed of 60,000 rpm.

The International Space Station's (ISS) most important legacy may be
jump-starting space tourism. Consider: the first space tourist, Dennis
Tito, was supposed to go to the Soviet era Mir space station. Under
pressure from NASA, Russia de-orbited the Mir which resulted in Mr.
Tito going to the ISS instead. Now the Mir was a terrific space
station, but by the time of Tito's trip it was also old, smelly,
crowded and probably not all that nice. The ISS was brand new, shiny,
much more roomy, etc. Mr. Tito came back to Earth with glowing accounts
of how great space is. Would his experience have been as good on Mir?

Al Globus
CSC at NASA Ames Research Center
http://www.nas.nasa.gov/~globus/home.html

Views expressed in this email are only my opinions and are not the
position of any organization I'm familiar with.