My Two Bits Ain't Worth 1E-15 (Take 2)

[Brian Mansur <bmansur@oc.edu>]

Okay, I just realized something about my two bits worth.  They ain't worth 
squat.  I ran the numbers for 11GW/ton/s on my portable RPB decelerator idea 
and came back to the same problem that Kelly has with his Explorer design. 
 We need too stinkin much power.

 Assuming 11GW/ton/s to accelerate a measly .036 g and using a De + 3He 
reaction that yields 3.606E14 Watts/kg and applying that over the time it 
takes to accelerate to 1/3c at .036 g the numbers got supremely ugly in 
terms of fusion fuel weight.

Back to the drawing board.

Perhaps the launcher idea could still work with the Explorer design.   What 
we have to do turn the Asimov into its own fuel launcher.  Have the ship 
rail gun launch most to all of the ship's reaction mass behind it.  The 
particles will have to be at least fast enough to cover  a .25 ly track in 
the time it takes to cruise to Tau Ceti.

I wonder: If we could keep the track together over that amount of time and 
distance, would it be easier to launch the track from Earth?  Would the 
stablizing system that Kevin told us about help?  I noticed this discussion 
but I don't know if it answers my question:

to: Timothy van der Linden

> >Ah, I see your mistake.  The angular deflection isn't based on the
physical
> >dimentions of the launcher, but on the accuracy and precision of the
lateral
> >correction trim thrusting, and deviation sensors.

> Yes, I was already expecting that something could be the case.

> >You measure the course of the accelerating packet with lasers and use
lateral
> >magnetic or electrostatic fields to adjust the direction.  (Its easier if
you
> >do this after it leaves the end of the accelerator.)  This way the final
aim
> >presision is not related to the size of the launcher.

> This assumes you can quite accurately steer a packet,
> but a packet is build up of a lot of small particles all
> going their own way (of course mainly forwards). ----

Who says?  A fuel packet could be the size of a fright car of that would
help, but I'ld assumed it would be smaller.  More like pill to bear can
sized.  It would almost impossible to spray a charged fog of particals out 
of
a gun and keep them together.  Their mutual repulsion would cause them to
defuse to much.  You'ld have to pack them in mini-containers.  I supose you
could treat those containers or packets as particals, but I don't think 
thats
what your thinking of.

So is the answer yes or no.

As the Asimov begins its deceleration phase, the relatively faster moving 
reaction mass track slams back into the ship.  We ionize the RM and run it 
through the accelerator for thrust just as if it were interstellar medium. 
 A downside to this idea is the drag caused by hitting the really fast 
particles at the end of the deceleration run.   Also there are going to be 
serious power cost to launch the track.

Kevin's 11.5 ly long power cord is looking better all the time.

Since we'll have to carry so much reaction mass for the launch track, I 
suggest we use the E18W we have planned to mag-sail launch the ship.   So I 
guess we launch the track via the ion accelerator using it as a rail gun if 
that is possible.

Someone else had better run the numbers on the drag and power needs.  That 
is if anyone thinks this has a chance of working.  If not, please show me 
the error of my ways.