FlyWheel Battery

> >
> >>> Rotational Kinetic Energy = 0.5(0.5 * Mass * radius^2)*angular
> >>> velocity^2
> >>>
> >>> Let's assume a flywheel operates at 3,000 r.p.m.
> >>> Let's assume a flywheel radius of 1 meter.
> >>>
> >
> > You can see from the equation that you get a lot from faster
rotation
> > (it's squared). I believe (and I could easily be wrong) that
current
> > fly wheel technology runs around 100,000 RPM or faster (anyone
know
> > the right answer?). If this number is about right then the
necessary
> > mass of the flywheel is much less.

Seeing how no one took up my invitation to analyze the stresses
acting upon the flywheel it looks like it's necessary to answer the
question of the possibility of a 100,000 r.p.m. flywheel.

I'm no engineer so please check my calculations.

Here goes:

Let's assume a flywheel operates at 100,000 r.p.m.
Let's assume a flywheel radius of 1 meter.
Let's assume a thickness of 1 cm on the rim of the flywheel.

The flywheel is comprised of 628.3 cm^3.
The mass of the flywheel is 628.3 cm^3 * 7.83 g/cm^3 = 4.9 kg

Force acting on rim of flywheel --> F = m(v^2/r)

Circumference of flyhweel is 6.3 metres.
1,666.7 revolutions per second.
Velocity is 10,500.2 meters/second

Force = (4.9 kg)(10,500.2 m/s)^2/ 1 meter = 540,245,580 N
Pascal = 1 N/m^2

The surface area of the hoop, or rim, of the flywheel is 0.063 m^2.

The force acting on the rim of the flywheel is 5.4 GPa.

The tensile strength of this steel is 1.75 GPa.

Therefore, this flywheel would break apart at 100,000 r.p.m.

SOLVING FOR THE LIMIT OF TENSILE STRENGTH

Fr/m = v^2

(175,000,000 N)(1 meter)/(4.9 kg) = 35,714,285.7 m/s

Velocity = 5,976 m/s
Circumference of flyhweel is 6.3 metres.
Thus, 948.6 revolutions per second.
The flywheel would spin at 56,916 r.p.m.

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.

Nevertheless, I still stand by my conclusion that battery systems
are complex, inefficient and expensive compared to power-on-demand
systems such as the electrical grid.

TangoMan