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What kind of drive do Cherryh's spaceships have?



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;Subject: cherryhlist
;Date: Mon, 11 Oct 1993 18:02:34 +0100 (MET)
;From: Onno Meyer <Onno.Meyer@arbi.informatik.uni-oldenburg.de>
(...)

I answered to that this morning, but now I have the quotes:

Obviously, there are three means of starship propulsion.
In a compendium, this would be supported by quotes.
1) The FTL-Jump using the jumpdrive vanes.
2) The "dump" and "boost" of realspace velocity using the jumpdrive or a subset of the jumpdrive. This is instantaneous.
3) A "rocket-like" engine that propells ships causing acceleration stresses for the crew. Engine 3) could play games with gravity to allow systemwide operations, but the only evidence I can think of are total accelerations that could be explained with drive 2).

Now, take the riderships. Obviously, they have 3), obviously, they don't have 1). The problem is wether they have 2) or not.

Pro:

"Tibet's rider was still heading in behind the wave of the original message, ... That rider was some minutes behind Tibet's message, insurance." DS 258/259 That rider obviously moves at a significant percentage of lightspeed. It can't do that on drive 3) alone.

"Atlantic and Pacific made their lonely patrol with all the riders in the Fleet, ..." DS319 A rider can reach the system fringes without carrier. Again, that can't be done on 3) alone.

"Pulse of the main engines. ... Second pulse, high-g RO, intermittent accel ..." HB325 "Pulse" is used to describe drive 2), the rider makes two pulses and then a RO.

IMHO, these qoutes prove that riders have drive 2).

Contra:

"Just the flat saucer shape. Manta shape, the blue-skyers called it." HB52 No vanes on a rider. Drive 2) uses the vanes.

"... trusting that realspace ships, launched like missiles, with more firepower than ability to maneuver at v,..." HB52 A rider has less maneuverabilitiy than drive 2) would give.

"Pulse of the main engines. ... Second pulse, high-g RO, intermittent accel ..." HB325 Drive 2) doesn't produce high-g. The rider engine makes two short, high-g bursts.

IMHO, these qoutes prove that riders have no drive 2).

Can anybody tell me where the flaw is?
Onno Meyer


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;Date: Tue, 12 Oct 1993 10:52:51 +0100
;From: Markus Stumptner <mst@vexpert.dbai.tuwien.ac.at>
;Subject: cherryhlist
(...)
>Can anybody tell me where the flaw is?
I think the contradictions are quite real, and the flaw rests with the original writing. Cherryh apparently wanted different effects at different times. If you want to reconcile the views, however, then I would say the flaw rests with this assumption:
>"Just the flat saucer shape. Manta shape, the blue-skyers called it."
>HB52 No vanes on a rider. Drive 2) uses the vanes.
Why does drive 2 have to have vanes? At the time when we discussed the possible differences between rider and carrier drive (assuming that riders were not simply reaction-based), I argued that there might be some difference that would provide savings in weight and/or money, but which kept riders from having jump capability. So, I postulate that it's the vanes which give the jumpdrive FTL capability, and the rider drive's "vanes" are so rudimentary that they fit within the hull. Consider the vanes as some kind of afterburner, for example.
	Markus


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;From: Jo Jaquinta <jaymin@maths.tcd.ie>
;Subject: Cherryhlist/riderships
;Date: Wed, 13 Oct 93 17:16:09 BST
>2) The "dump" and "boost" of realspace velocity using the jumpdrive
>   or a subset of the jumpdrive. This is instantaneous.
I'm pro #2. Let me conjecture:
>"Just the flat saucer shape. Manta shape, the blue-skyers called it."
>HB52 No vanes on a rider. Drive 2) uses the vanes.
One can assume that the optimal configuration for the vanes of an interstellar ship is wide-spread in order to best project the jump field. We already know from the refitting of The Pride that the area (# of panels) to mass ratio is crucial.
This is a jump configuration optimal for sending large masses through the Deep between stars. It is a related, although secondary function, that allows the ships to boost and dump.
What does a manta look like? It's got two big wings either side. Perhaps this is the optimal configuration for the panels when interstellar jumping is not required.
>"... trusting that realspace ships, launched like missiles, with more
>firepower than ability to maneuver at v,..." HB52 A rider has less 
>maneuverabilitiy than drive 2) would give.
Drive 2) isn't particularly maneuverable. It can slow you down quickly or speed you up quickly but only the knnn can use it for inter-course maneuvers.
>"Pulse of the main engines. ... Second pulse, high-g RO, intermittent
>accel ..." HB325 Drive 2) doesn't produce high-g. The rider engine
>makes two short, high-g bursts.
I have difficulty beleiving in a completely inertialess system. Inertially damped, yes. Thus the massive acceleration/deceleration of drive 2) is damped down to just high-g. Are they any instances where a ship dumps without everyone strapped down?
			Jo


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;Subject: cherryhlist
;Date: Thu, 14 Oct 1993 10:13:21 +0100 (MET)
;From: Onno Meyer <Onno.Meyer@arbi.informatik.uni-oldenburg.de>
(...)
> 	I have difficulty beleiving in a completely inertialess system.
> Inertially damped, yes. Thus the massive acceleration/deceleration of
> drive 2) is damped down to just high-g. Are they any instances where
> a ship dumps without everyone strapped down?
Markus thinks (nearly) the same about the vanes. But if a spread vane is not the best for maneuvers, why no warships with two vane sets? A carrier can operate without one jump vane (see DS). That vane could become a "insystem" drive. On the inertia question, it has to be nearly 100% damped. I can't get the accel required to bleed, say 10%c away in an instant in my head, but it has to be enormous. If you can negate thousands of g, why should a few g remain undamped?
Onno


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;Date: Thu, 14 Oct 1993 11:13:33 +0100
;From: Markus Stumptner <mst@vexpert.dbai.tuwien.ac.at>
;Subject: cherryhlist
(...)
>	Drive 2) isn't particularly maneuverable. It can slow you
>down quickly or speed you up quickly but only the knnn can use it
>for inter-course maneuvers.
Doesn't this distinction somehow postulate an absolute frame of reference? I think this may be a problem.
(...)
>	I have difficulty beleiving in a completely inertialess system.
>Inertially damped, yes. Thus the massive acceleration/deceleration of
>drive 2) is damped down to just high-g.
Good point. The "intermittent accel" also would tend to indicate some kind of "buffeting" that gets through instead of the main effect of the drive.
	Markus


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;Date: Fri, 15 Oct 1993 14:37:35 +0100
;From: Markus Stumptner <mst@vexpert.dbai.tuwien.ac.at>
;Subject: cherryhlist
>Markus thinks (nearly) the same about the vanes. But if a spread vane
>is not the best for maneuvers, why no warships with two vane sets?
I'd present it the other way round: A non-spread vane is *sufficient* for maneuvering, but not for FTL jumps. Spread vanes are obviously suitable for FTL and maneuvering, but would have other disadvantages (e.g., larger mass, and a vulnerable structure with large cross section).
>On the inertia question, it has to be
>nearly 100% damped. I can't get the accel required to bleed, say 10%c 
>away in an instant in my head, but it has to be enormous. If you can
>negate thousands of g, why should a few g remain undamped?
I agree with the "nearly 100%". However, if you actually have 1000s of g's, then an imperfection of less than one percent *will* already translate into multiple g's, so I think this fits anyway.
	Markus


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;Subject: Cherryhlist
;Date: Mon, 18 Oct 1993 09:26:33 +0100 (MET)
;From: Onno Meyer <Onno.Meyer@arbi.informatik.uni-oldenburg.de>
> I agree with the "nearly 100%".  However, if you actually have 1000s of
> g's, then an imperfection of less than one percent *will* already translate
> into multiple g's, so I think this fits anyway.
Quotes from ML show that - at least on merchanters - the boost/dump affects mostly (only?) the nervous system. About the vanes, I just wondered why they are spread out at all. You could have vanes along the hull and turn the whole ship just before jump.
Onno Meyer


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;Date: Tue, 19 Oct 1993 11:36:26 +0100
;From: Markus Stumptner <mst@vexpert.dbai.tuwien.ac.at>
;Subject: cherryhlist
>Quotes from ML show that - at least on merchanters - the boost/dump
>affects mostly (only?) the nervous system. About the vanes, I just
>wondered why they are spread out at all. You could have vanes along
>the hull and turn the whole ship just before jump.
If you have some kind of perturbations (gravitational or whatever) near the vanes when using them for a jump, then you would not want them close to the hull.

The point is that with the very limited knowledge we have, it is fairly easy to find another addition to the theory that will justify things as they are presented in the books. I don't think we should carry this too far. After all, the drive with them vanes is no less magic from the POV of physics than the postulated rider drive without them. Of course we all know that the vanes are in the books because they make the ships look neat - more technical than just a cylinder- shape - and the riders have no vanes because they're supposed to look sleek and mean. :-)
	Markus


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;Subject: cherryhlist  - ship design
;Date: Mon, 24 Jan 1994 12:20:01 +0100 (MET)
;From: Onno Meyer <Onno.Meyer@arbi.informatik.uni-oldenburg.de>
(...)
 
> - Concerning an old thread:
>   Using the interface (to subspace) a ship may accelerate/dump speed. 
>   I think it's also possible to change direction within limits using
>   the interface. Otherwise I'm not convinced of the disadvantage of
>   small speeds, when any greater change of course must include a
>   stand still of the ship... Perhaps the interface acts as kind of
>   multiplicator of the normal space engines (Legacy: The Legacy cannot
>   accelerate as fast as it could because of it's Stsho passengers'
>   inability to stand more than 1.5g. But the main part of the velocity
>   must be gained/dumped by use of the interface! Legacy p224: 4h from
>   Kita and they were approaching jump (ship-time?)).
> Peter
If you imply by "multiplicator" that the vanes add to the effect of running engines, I disagree. The velocity changes come in bursts. Perhaps the velocity (in a frame of reference with the local gravity well) is multiplied with a constant every time the vanes pulse, and the ships use their realspace engines to get something worth multiplying.

(...)
Onno Meyer


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;Subject: cherryhlist - various answers
;From:	Peter Jakobi <jakobi@informatik.tu-muenchen.de>
;Date:	Tue, 1 Feb 1994 06:41:19 +0100

(...)

re Jo on insystem drive:
------------------------
1. As I figured it, the mains are working less than several hundred hours, the real speed comes from the interface (get some v and some distance to other mass and 'un'dump). So for trader's the power source should not be to critical (CH run to Anuurn: about fuel capacities required for the non-stop run)

2. Can you mail the summary of the reactionless insystem drive hypothesis? Thank You.

(...)

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