RE: ship gravitics, was take off procedures

[This came to [email removed], looks like it was meant for
[email removed].  Watch those automatic reply headers! -- James]

       EIGHT WORLDS DRIVE SYSTEMS AND FLIGHT OPPERATIONS

Drine Systems
     Eight Worlds physics does not seem to allow for gravitics
technology.  Eight worlds ships have three drive systems:

     1) Hyperdrive.  Hyperdrive relieves much of the tedium of
interstellar travel, provided that no attempt is made to employ
it too near an interfering mass.  If this precaution is omitted,
the ship explodes, relieving ALL the tedium of interstellar flight.
The minimum distance at which hyperdrive can be employed without
explosive consequences (the infamous 'jump limit') is dependant
upon the intrinsic curvature of space, which quantity is, of
course, equivalent to local tidal forces.  Thus, the jump limit is
proportional to the cube root of the interfering mass.
     The jump limit for a terrestrial mass is about 1.0E+06 km.
The jump limit Sol is somewhere around the orbit of Mercury.  Or
perhaps Venus.  Who cares?  Both are worthless rocks.  The point
is that hyperdrive CAN be used for intrasystem transit, should one
wish to travel to Io to replenish one's sulphur supply.  This is NOT
the case in a system of habitable planets in orbit around a star of
type M or smaller.  Which had important strategic consequences after
the collapse of the Imperium.
     Hyperspace jumps appear to conserve momentum.  Certain aspects
of hyperspace jumps appear to allow for violation of causality, but
the relevant experiments are beyond the finacial capacity of any
existing civilization.
     2) Fusion drives.  These are open core magnetic confinement
fusion reactors which function as high specific impulse reaction
drives.  (The most common configuration is a leaky tandem mirror
machine which burns D + D -> Useless Hot Junk.  The Useless Hot Junk
heats reaction mass to provide thrust.)  Fusion drives are are used
for planetary approaches and departures, to match velocity with a
destination, and for Space Laser Tag, a fast-paced competitive sport
with a simple and easily understood scoring system which is quite
popular beyond the Frontier.
     Drives are not particularly useful without associated structure
to keep the ship from collapsing.  I lump the mass and cost of the
load-bearing structure in with the mass and cost of the drives.  An
interesting consequence of this approach is that it does not matter how
much acceleration the ship pulls.  The structure of a 200 tonne ship
with 200 tonnes of cargo accelerating at 2 Gs is under the same load
(4 MNewtons) if the ship dumps its cargo and flees at 4 Gs.  The crew,
however, may notice a subtle change in their level of squishedness.
     Since fusion drives have open cores, they can't be used inside
an atmosphere lest the atmosphere leak in around the sides of the
plasma column, induce heavy-ion instabilities, and cause the ship
to explode boom.
     3) Atmospheric drives.  These are commonly known as 'Lifters',
and consist of an assortment of thermal turbojets and scramjets
driven by waste heate from the power plant.  (Eight worlds power
plants are closed core high-field magnetic confinement devices
which commonly use the D + Li6 -> 2He4 cycle.  The energetic alpha
particles are then run through an MHD generator.  No muss, no fuss,
no radiation, and if there are any leaks in the system the crew all
sound like Donald Duck.  It's great.)  Lifters are used to lift off,
tool around the planet, depart the atmosphere, or land.  In the hands
of unskilled crew, lifters can also be used to crash.
     Since lifters are part of the technology necessary to land on
a planet, I lump them in with streamlining, along with the aeroshell,
stabilizing fins, landing jacks, and paint job.  The thrust limitation
for lifters is imposed by the ship's load-bearing structure.  There
is no obvious benefit to attaching a 200 MNewton lifter system to
a ship which can only stand 8 MNewtons of thrust.

Flight Opperations
     This is, of course, all very great and keen and all, but does not
answer the question 'How do you land these things?'  (A question I have
often asked while landing my hang glider.)
     Most Eight Worlds ships are tail-landers (The drives are aligned
along the aerodynamic axis of the ship and they land on their tails...
What WERE you thinking!)  This is a fine and dandy configuration which
has been used successfully on any number of wierd experimental aircraft
back during the 1950s when they didn't know any better.  There was
also a bizarre proposal to build a tail-landing version of an F-16
for use on small naval vessels.  Ick.  Tail landers are not all THAT
hard to land (my hang glider is arguably a tail lander if it is landed
correctly.  At other times it is a nose lander), but they can fall over
once they are on the ground.  The usual cause of such accidents is
soil failure, which grows more likely as the weight, and hence the
ground pressure of the ship, increase.  The maximum safe weight for
landing a tail-lander on a compacted dirt field is 400 tonnes, which
co-incidentally is the size of most Eight Worlds trading ships.  My
my.  Another cause of toppling incidents are careless PC starcrew who
land their ship on a 45 degree slope.  It was fun, it was great, you
should have been there.
     An alternative configuration is a belly-lander.  Belly-landers have
their primary drives aligned along the aerodynamic axis, but possess
an additional set of lifters or a thrust vectoring scheme which allows
them to hover in a horizontal orientation.  That this scheme is feasible
is proven by one of NASA's AV-8 Harriers which even now is hovering
outside my window producing a terrible racket and making it difficult
to do any serious work.  Belly-landers are more stable on the ground,
a field which can handle a tail-lander can handle a belly-lander of 2-3
times the size.  With their extra lifters they are also a tad more
manuverable in the atmosphere.  But belly-landers have two problems:
     1) There is an extra mass and cost penalty, equal to 50% the cost
of streamlining.  This penalty has proven prohibitive for small ships,
which do not need belly-landing gear anyway so who cares.
     2) The coffee mugs fall off the shelves.  This problem is generic
generic to all Eight Worlds ships when they make the transition from
space to atmospheric flight, but it is much worse for belly-landers
since it persists after they are on the ground.  Eight Worlds ship
designers use lots of velcro, and draw heavily on 1950s Sci Fi flicks
for their deck plans.  The results are agreed by all to be somewhat
unsatisfactory.

More Flight Ops
     Nope.  No more flight ops.  I lied.

Paul R. Gazis
Sunnyvale, CA

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