Re: Reactionless drives

William Dow Rieder [email removed] writes:
> Adrian Hurt writes:
> >I think what Bertil was trying to say is, what is wrong with turning a ship
> >from having X megajoules of energy stored as potential energy, to a ship
> >having .9 X megajoules of kinetic energy and .1 X megajoules of waste energy
> >(e.g. heat) without having to dump a load of stuff out of the back to satisfy
> >Newton?

>								   Even if you
> use Bertil's idea of  (Energy needed for drive = KE added to ship) it doesn't
> work because you need a non-accelerating reference frame to measure KE.

Oh, *@!~.  Relativity strikes again. :-)

After reading this, I did a bit of working out on some scrap paper myself,
which started out with conservation of energy and ended up with conservation
of momentum.  If you really want a long, boring load of ASCII, I can post it
here.  Suffice to say, I was right to leave all those exhaust nozzles on my
model ships!

There is one possible loophole, which someone on rec.arts.sf-lovers suggested.
So-called "reactionless" drives are nothing of the sort; they use the rest of
the universe as a reaction mass.  Someone else can figure out how, or if, this
can be done.  I'm sticking with rockets - they make the models look better.

> I worked all out with a friend for fun when we were building MT
> perpetual motion machines. (So I'm weird - sue me)

You want perpetual motion machines?  Try assuming that a black globe absorbs
gravitons and see what happens.

- --
 "Keyboard?  How quaint!" - M. Scott

 Adrian Hurt			     |	JANET:  [email removed]
 UUCP: ..!ukc!cs.hw.ac.uk!adrian     |  ARPA:   [email removed]