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Draft text Externally fueled Fusion drive

Heres some more text to look over.  Attack at will.  This is what I
consider the baseline drive system for my Explorer class design.


Oh, if anyone wants.  I can send set of the graphics and HTML files for
this and the others.  Let me know.

Primary Drive System:
Externally Fueled Fusion Rocket

Out of the likely ashes of my Multi-cycle Ram Augmented Interstellar Ramjet
(RAIR) drive, I kept one solid piece. The idea of launching fuel to the
ship from a fixed launcher in Sol (our home starsystem).  The fuel/reaction
mass mixtures could be launched as anything from aspirin sized pellets, to
truck sized expendable mini-tankers.  The former could be scooped up and
fused as is, the later could could be docked and off-loaded.

I'm not going to go into a detailed analysis of the pros and cons of the
different systems, but their are a lot of pros and cons for each.  A stream
of pellets would be easier to launch and offer less impact danger to the
ship.  But the pellets would be harder to keep together at a distance from
the launcher, and harder for the ship to recover.  The ship would need a
ramscoop to scoop up its fuel, and when the packets drifted to far to the
sides, the ship couldn't pick them up.

Mini-tankers on the other hand could use onboard rockets to maneuver to
meet the ship.  Possibly the ship could beam power to them (via lasers or
microwaves) that could be used to drive the tankers attitude rockets, and
order it to maneuver in front of the ship for pick up.  Or a system like
passive laser launchers could be used.  These would just require the tanker
to have a large block of reaction mass on its backside.  The ship could
boost, and steer the tankers remotely using lasers.  Without any equipment
on the tankers.  Either way the ship could catch fuel tankers that had
drifted thousands, possibly tens of thousands of miles off to the side of
the ships flight path.  Far more then possible with scoop system.

Either way an externally feed system would mean that, the ship wouldn't
need to carry the tremendous tonnage of fuel and reaction mass it would
need for the flight.  Launched fuel and reaction would only be carried by
the ship from the time it entered the holding tanks, to the time it was
burned.  How this would work in each phase of the flight is described below

Accelerating out of Sol, our star system.

The ship would be heavy.  Not only with the weight of its own systems and
structure, but food and equipment for the mission, exploration equipment,
the crew and their homes; and weighing dozens of times all the rest
combined, deceleration fuel (See fusion rocket mass tables).  The ships
final cruse speed will be limited to the maximum speed it can decelerate
from with the amount of fuel it can carry.  Given the years of flight time
involved, every effort will be made to load the ship with fuel.

Pulling out of Our star system, Sol, the ship will accelerate at one ship
G, accelerating 10 meters per second, per second.  A orbiting launcher will
launch the fuel and extra reaction mass the ships motors will need.  The
ship will be continuously picking up these fuel packets, and feeding their
contents into the fusion motors.  This will continue until the ship reaches
the maximum speed it can slow down from.  If the orbiting launcher can
still get fuel close enough to the ship for it to pick up, extra fuel can
be set out to increase the breaking supply.  Possibly allowing the ship to
accelerate a little more, giving extra speed for the long flight.

Because of the deceleration fuel limitation, it is unlikely that the ship
can get to more than a quarter or a third of the speed of light.  But
that's still a 100,000 kilometers per second.  The ship will need to
protect itself against impacts.  One of the simplest ideas is to push
several miles of charged dust ahead of the ship.  Ramming a cloud of
charged iron dust at a 360,000,000 kilometers per hours will turn most
anything into ionized plasma.  Which can be shoved ahead of the ship, or
off to the sides, by the charges dust cloud handler.  Effectively most
anything you run into at speed will become more shielding dust.

Decelerating into the target star system.

Now for the bad news - you have to slow down.  We can't pre-load a
deceleration course track into the target star with fuel across
interstellar distances.   So your stuck with the fuel you brought along.
Unless we can come up with a neat magnetic trick to brake the ship in empty
space (sorry no luck), its fire up the reactors and put things into

Cruising around the target star system

At low speed interplanetary runs, the drive works like a conventional
fusion rocket burning stored fuel and reaction mass.  But the engines that
could get us across interstellar space only with difficulty.  Can now make
this huge ship commute around the confines of a starsystem with ease.  A
ten hour burn of the main engines will would get you from earth to Jupiter
in about a month, or Mars in a week.  A two day burn would get you to
Jupiter in less than a week.  Under four days of constant burn will get you
to Mars.  About a week of constant burn will get you to Jupiter.

Once in system the main ship will be shuttling surface teams, support
ships, and equipment around the star system.  It size and speed will allow
it to drag around tremendous loads of equipment or raw material.  It could
haul ore in to a construction site for a space colony.  Or to a fuel ore
processing facility.  It will be carrying all the exploration equipment and
personnel to anywhere of interest in the starsystem.

Accelerating out of the system to go home.

As the exploration phase comes to an end the support crew will be
processing the tremendous tonnage of fuel ore necessary to refuel the ship
for the boost to home.  This fuel could be carried on the ship.  All those
fuel tanks you emptied decelerating into the starsystem could be filled to
accelerate you back to home.  Or (possibly) the crew could construct a fuel
launcher like the one the ship used to leave home.

If an automated fuel launcher could be constructed in the target
starsystem, and the one near earth relied upon for braking fuel, the ship
could launch with her fuel tanks nearly empty.  Without the massive load of
fuel and exploration equipment the ship could weight a hundredth of its
loaded weight when it left Sol.  This would allow it to boost faster and to
higher speeds, even if the local fuel launcher could only launch a tiny
fraction of the fuel the Sol launcher could, even if most of the drive
reactors and motors were disabled.  Potentially giving this missions crew a
much shorter flight home, and allowing future missions into this star
system a much shorter round trip.

An automated fuel launcher maybe to complicated to big for the crew to
construct.  But if enough construction gear can be brought along (or some
ultra tech like self replicating machines is assumed), this would greatly
expand the amount of flights and exploration we could do to this star

Decelerating into of Sol, our star system.

Since the ship can assume that the orbiting fuel launcher in Sol will be
turned on to help it slow down.  The ship wouldn't need to be heavily
loaded down with deceleration fuel.  By this point in the mission the ship
will be comparatively light.  Its fuel tanks empty.  Most of the food and
consumables consumed.  Probably most of the exploration gear left behind.
The ship will be coming home needing fuel.  Or will it?

The ships cruise speed will be a fraction of the speed of light, and it
will be flying straight toward the fuel launcher.  Obviously a nice neat
docking with the incoming fuel packets is out of the question.  You could
of course use the lasers to steer a mini-tanker in front of the ship and
then explode the tanker.  The contents will slam into the ships forward
dust shield and be heated to plasma.  That plasma could be scooped up and
channeled into reactors to power the reverse engines.   Or Is that

Whatever blasts through the dust shield is going to be hot!  The forward
electromagnetic barriers that shove the dust ahead of the ship are going to
be ramming into, pushing forward, a plasma ball an eight of a mile in
diameter and length unknown) ahead of the ship.  If their is any fusion
fuel in the mess, its probably going to be fusing out ahead of the ship.
Effectively the front of the ship will be an open fusion motor.  If the
launcher isn't firing fuel.  Whatever it is launching is still going to be
a hellish fireball ahead of the ship.  Effectively the ship will be
breaking against this artificially induced drag source.

You wouldn't even need to run the reactors to keep the electromagnetic nose
shield charged.  Ducting a little of the plasma through a central core will
allow you to use the core as a generator.  Converting the energy of the
high speed plasma into electricity.  Or more correctly converting the ships
kinetic energy past the plasma stream into electricity.  If you want to get
tricky a magnetic 'wiggler' in the plasma stream could be used to lase it.
The forward blast from a plasma laser charged by the kinetic energy of a
few hundred thousand tons of charging starship should clear anything out of
your path.  It certainly will show everyone the explorers have returned


Kelly Starks                       Internet: kgstar@most.fw.hac.com
Sr. Systems Engineer
Magnavox Electronic Systems Company
(Magnavox URL: http://www.fw.hac.com/external.html)