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Re: starship-design: Plasma Drive...

Adam Crowl wrote:
> Hi SD,
> That's a bloody good Idea Kevin. Beamed power without the need for totally
> beamed power, just a kind of top up. A pure microwave system never struck me
> as safe, but a plasma storage system has an advantage...
> > Very interesting.  I like that it is microwave powered.  You could make a
> > really nice beamed launch vehicle.  A little bit of water to start things
> > off, then breathe air until you clear the stratosphere, and then use
> > whatever reaction mass you are using (I suggest water).  The whole time,
> > you can continue to add energy, so that the craft has full power when it
> > reaches space.
> >
> > The power station stays on the ground, next to the Hydroelectric plant (or
> > whatever) that generates the power.
> > >to travel around the world! It'd just compress and heat normal air...
> > >Applied to a space launcher the savings could be immense, and applied to
> Mars mission the mass would go from ~ 600 t [split between three
> launches to one launch of about 120 t! That's an 80% saving in mass and God knows
> how much in equipment and development.
> Ultimately it could go into a system using small sub-plasmas for thrust
> and achieve maybe 60,000 s Isp... I can see real potential for this coupled
> with a Bussard fusor for high speed Deep Space missions...

I don't think the plasma will scale to make a large space launcher possible.
My guess is still a air launched pseudo SSTO space plane with a payload in the
2-3 ton
range for low earth orbit. The problem is scaling and heat flow. I suspect a
external field of some kind will be needed to keep the plasma stable for energy
and removal. ( Mr Fusion of "Back to the future" comes to mind here for a
successful reactor
size wise <grin>). The heat produced from say a 70% efficient engine still has
to fed through small area.
Assuming a 10^9 J? plasma  we are looking at about 3 feet diameter with a 1 foot
That's a lot of heat and external forces wanting to push the  field out of
shape. I wonder
how the field would explode if pushed out of shape? Lots of nasty X-rays is my
quick calculations ... 2 ton payload 3 ton unmanned craft ... Isp = 6,000. g=32
mi=5 tons
v 30,000 ft/sec
Mf = (e(V/(g*isp)-1)Mi  = 1 ton.
I wonder if C4H would work for fuel?

"Everything should be made as simple as possible, but not simpler."
 	Albert Einstein