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: 21 Dec 1992 01:14:18 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 <1992Dec21.004947.11290@cis.ohio-state.edu>, rubin@grape.cis.ohio-state.edu (Daniel Rubin) writes:
=OK I agree that cars do not expode like seen on the big screen.  A car
=can expolde though.  Take the above example and add a high amperage electrical
=system and loads of wires to the top of the gallon of gas.  Now if the
=conditions are good the gas will spatter the vapor will come in to contact
=with a spark from two shorting wires and you will get a nice explosion.  

Albeit a small one.  Unless, of course, you wait for quite some time for the
gasoline to evaporate.  Of course, you'd better wait for a very calm day; other
wise you're never going to get enough fuel/air mixture in the right proportions
to make a satisfactory explosion.

=Fuel-Air explosions are quite nasty.

It's also rather difficult to arrange for any but small ones outdoors.  Now,
inside the bilge of a boat, on the other hand....

=Buring gas will not do that much, but
=produce heat, whereas buring gas vapor mixed with oxygen in the air will
=produce a powerfull explosion...

Sure it will.  If you manage to mix them in the right proportions.  Now, for
the comparision with the flywheel, please answer the following questions:
	1)  How long do you figure it would take for two gallons of gasoline to
	    evaporate?
	2)  Given that length of time, what do you think the chances are that
	    you're going to get two gallons of gasoline in an explosive
	    fuel/air mixture before much of the mixture has blown away?
=Try it.  Drip a few drops of gas in a fire pit or some other similiar type of
=open ended enclosure ( no more than 5 or 10 drops of gas ).  Wait for it to
=vaporize and then throw a match in.  Whooomppp you will feel the shock wave
=and it most likely with scare the sh-eck out of you...

Right.  Think about the size of that explostion from about half a dozen drops
of gasoline.  Now, consider that the flywheels being discussed in this thread
would store the energy equivalent of two gallons of gasoline.  NOW DO YOU AT
LAST BEGIN TO COMPREHEND THE AMOUNT OF ENERGY WE'RE TALKING ABOUT RELEASING IN
A CATASTROPHIC FAILURE OF A FLYWHEEL?

And, unlike the gasoline, which has to be mixed with air in the proper
proportions, and which has to evaporate before this happens (which
	11) make the likelihood of an explosion smaller
	2) makes it likely that any explosion will only involve a small amount
	   of the gasoline;
	3) means that people have several minutes to get away from the vehicle
	   before conditions are right for a large explosion),
ANY failure of the flywheel releases ALL the energy stored in the flywheel in
on the order of a second or less.  Every time.  Period.
=>Because gas tanks don't explode. Movies are not reality.
=
=Car crashes violently, gas tank is ruptured and gas is forced out of the 
=rupture by the crash.  Gas vapor cloud forms rapidly and comes in contact 
=with the shorting positive battery post agains the frame of the car.  That
=will cause a rather large explosion and quite a lot of fire.

The amount of energy likely to be released in such an explosion is a small
fraction of the amount that would be released should a flywheel like the ones
under discussion fail.
--------------------------------------------------------------------------------
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.