message 0557

• How do the spaceship drives work? And what about the underlying 'Jump mechanics'?

>From: Jo Jaquinta <jaymin@maths.tcd.ie>
>Subject: CherryhList/ More thoughts on Jumpdrives
>Date: Tue, 21 Sep 93 8:37:28 BST

Coalating various people's observations and quotes on jump-drives
you might consider a different approach.

	Jump drive does not, in and of itself, form a propulsion system.
Instead we can interpret "boosting" and "dumping" as just that. The
jump drive magnifies the effect of whatever propulsion system.
	This can happen in one of two ways: (1) modifying the inertia
of the ship or (2) modifying the effectiveness of the, say by changing
the mass. We can look at each of these in the three described uses of it:
(A) pulsing the vanes up or down, (B) jumping between stars, and
(C) destroying starstations :-).
	[Adopting Traveller terminology I will refer to their "realspace
drive" as the "maneuver drive" or M-drive and the "trans-solar" drive as
"jump drive" or J-drive.]
	1.A) It could take the current inertia of the ship and 
dampens/enhance it. I.e if we are buzzing along at .8C and hit the dampers 
it might halve our inertia and dump us down to .4C. We hit it again and 
we dump down to .2C, again and we're at .1C. Or something like it dampens
inertia by 10% per second of activation.
	Warships have bigger Maneuver Drives and so can initially
gives themselves a bigger kick to be enhances thus improving overall
acceleration. Similarly they can stop dumping earlier since they can
handle much higher velocities with their M-drive alone.
	2.A) We can postulate that the vanes affect the preformance of
the normal maneuver drives. The easiest way I can think of this is if,
say, it could magically reduce the mass of the ship. Depending on the
vane-to-mass ratio we might get a ship down to a fraction of its original
mass.
	Thus the normal M-drive when fired under the vane effect would
obviously accelerate it considerably more. (Note: the M-drive *must* be
a reactionless drive, otherwise there would be no net gain). Whatever
reduces the mass would also reduce the effects of 40+G acceleration on
the ship superstructure and crew.
	Thus warships have M-drives and can accelerate faster under the
J-drive effect giving them multiply enhanced boosts and dumps.
	1.B) If pulsing the vanes in-system magnifies your inertia
then activating them for jump would magnify it trans-relativistically.
We know you have to be pointing in the right direction (many references
to braketing stars in sights) and you hit the J-drive and *zing* off
you zoom in that direction.
	2.B) Similarly to the above when the J-drive is fully activated
we can reduce the ship's mass effectively to zero (or maybe negative?).
This allows the Einstinian barrier to be breached and trans-light
velocities achieved.
	3.A) How can boosting inertia destroy a stationary station?
There are two types of inertia/momentum. Linear inertia (an object in 
motion tends to stay in motion) and rotational momentumn (a spinning top
keeps spinning). If we boots the rotational momentum of an object it
will spin catastropically fast. This is supported in that we do see ships 
stopping their rotation before jumping.
	Alternatively it could be a requirement that it boosts inertia
in the direction in which the drive is aligned. when docked at station
the overal momentumn is not aligned with the drive. In such a case the
consequent instabilities could rip the station apart.
	3.B) We can therorise that the jump field does not have a uniform
effect in mass reduction but that over the size of a ship the differences
are not relevant. But over the size of a station if the nearest part
is, say 1% of normal mass and the far par, say 5% than you will have
severe structual instability. Espicially if your M-drive cuts in with
a big kick.

	For either (A) or (B) riderships are just ships with very good
M-drives but only enough J-drive to perform (1).
	Upon examination it seems there is more textual support for
theory (A), although personally I prefer (B). Can anyone remember other
passages with support or undermine either?

			Jo Grant