From: carl@SOL1.GPS.CALTECH.EDU (Carl J Lydick)
Newsgroups: sci.electronics,sci.energy,rec.autos.tech
Subject: Re: Flywheel batteries as EV power source
Date: 16 Dec 1992 23:33:01 GMT
Organization: HST Wide Field/Planetary Camera
Distribution: world
Reply-To: carl@SOL1.GPS.CALTECH.EDU
NNTP-Posting-Host: sol1.gps.caltech.edu

In article <1992Dec16.192456.6261@news.cs.brandeis.edu>, andyh@chaos.cs.brandeis.edu (Andrew J. Huang) writes:
=In article <1992Dec15.194558.2556@adobe.com> pngai@adobe.com (Phil Ngai) writes:
=<regarding flywheel energy storage>
=>But how hot would this "cotton" be? You're dumping what is presumably
=>the equivalent of several gallons of gasoline's worth of energy.
=>That's a very large amount of energy.
=>
=>I hope they do lots of crash tests before unleashing such a dangerous
=>technology on the unsuspecting public.
=
=<I have to admit an emotional response to this since I think that
=flywheels have tremendous potential.>

The problem isn't with their potential, it's with their kinetic.

=1. I think that it is unfair to call it "such a dangerous technology"
=based solely on your own opinions, without having done any
=investigation on your own.
=
=2. There are several places for the energy to go during an explosion.
=Since the energy is kinetic, a lot of it will end up as particle
=velocity.

Partcles of what?

=Some will dissipate into the air as air friction (some hot
=air as a side effect).

What air?  The flywheels are supposed to operate in a vacuum.

=A quantity of energy will go into the
=mechanical breaking of the flywheel disk itself.

True.

=Some more will go into the penetration of the flywheel housing.

True.


You seem to've missed something here.  It's called the law of conservation of
energy.  While energy will go into these paths you can't just say, as you're
trying to:
	A lot of it will end up as particle velocity, so now we can ignore that.
	Some will dissipate into the air as air friction (some hot air as a
		side effect), so now we can ignore that.
	A quantity of energy will go into the mechanical breaking of the
		flywheel disk itself, so now we can ignore that.
	Some more will go into the penetration of the flywheel housing, so now
		we can ignore that.

=What residual energy escapes these will have to be determined by testing.

Er, the amount of energy that escapes is exactly the amount of energy you
started with.  Law of conservation of energy comes into play.  All the energy
from the flywheel will have been converted into these other forms, as you point
out.  That doesn't mean we can ignore it.  True, we're not likely to be talking
about hypersonic bits of the flywheel.  But enough energy to move that vehicle
on the order of 100 miles at freeway speeds is still around there someplace. 
It didn't just vanish.  And that's a LOT of energy.  And it got dumped FAST.

In other words:  BOOM!

Unless you wrap the flywheel in a massive enough container that it can absorb
all that energy without vaporizing, you're going to have an explosion.
--------------------------------------------------------------------------------
Carl J Lydick | INTERnet: CARL@SOL1.GPS.CALTECH.EDU | NSI/HEPnet: SOL1::CARL

Disclaimer:  Hey, I understand VAXen and VMS.  That's what I get paid for.  My
understanding of astronomy is purely at the amateur level (or below).  So
unless what I'm saying is directly related to VAX/VMS, don't hold me or my
organization responsible for it.  If it IS related to VAX/VMS, you can try to
hold me responsible for it, but my organization had nothing to do with it.
Xref: sparky sci.electronics:21232 sci.energy:6290 rec.autos.tech:16971