Thoughts on TL9 Spin Capsules

[Antony]

I was just having a thought about lower tech starships of this tech level. From FF&S you basically having variations on spin, spin capsules, hamster cages that sort of thing.
This led to that, will these systems work in jump space? I don't think it has been covered anywhere if it has let me know where.

First assumption that these systems can still produce the pseudo artificial gravity.
Hamster cages probably not a problem but I have a problem with spin capsules which is what smaller vessels would have to use (if they have any system at all) you know a capsule(s) tethered to the ship and rotated around it to produce the psuedo grav.

o---O---o

Spin capsules extended

o-O-o

Spin capsules retracting

oOo

Fully retracted

Something like this arrangement where the outriggers are the spin capsules and rotate around the ship. This version means that the vessel would presumably need a larger jump drive to contain them. Alternatively the outriggers are locked in place and the entire ship rotates but that would I suspect produce its own problems in the main hull (The pseudo grav is less but the relative rotation is greater in degrees per time period. The spin capsules normally contain only staterooms, some labs. The main hull would still have the manuver drive, sensors etc.

The diagram shows the spin capsules open and retracted to the main hull. This would be needed for the craft to be capable of landing anywhere or when high g maneuvers are going to take place spinning capsules are going to make quite a nice gyroscope for the ship. In fact the ship would probably need something to counter this effect if attempting to manuever with these things spinning.

Any other thoughts?

 

[Theophilus]

Have you ever looked at Pod9's Jovian chronicle game?

They use two types of spin capsules, cabled and fixed (think leonov from 2010)

The cabled versions reel out for spin, and are reeled in for acceleration.

The spin cage is fixed "pod" on a pivot for use while spinning or accelerating, shaped like a T the ship is accelerating:

T> direction of acceleration
< directon of Gravity
When the ship uses spin gravity the pod changes to verticle like an I

I /\ spin induces "upward" gravity

T I pod
0 0 pivot
I I strut

get the idea

 

[aramis]

I suspect that the extended mode would be the default for jump if using grid-based drives ala MT; but given the coil based drives mentioned in TNE products, it's quite likely the coils generate some form of shaped field anyway (otherwise they would need to generate a spheroid, possibly oblate, for a volume larger than any non-spheroid ship). In the latter case, extending the pods would be a requisite part of jump...

 

[Peter Schutze]

>I don't think it has been covered anywhere if it has let me know where

the whole traver:2300 / 2300AD game ship rules are dependent on spin gravity rather than artificial gravity

Fire Fusion and steel, the tech book for one of the versions of real traveller also has stuff for spin designs

 

[epicenter00]

I was always under the impression that the point would be more or less moot. I thought Traveller jump fields of any kind were a function of mass instead of volume or surface area - a ship's mass isn't going to change because it has spin capsules extended or not. If surface area factors into things, then I think any kind of "odd" hull shape is going to have similar problems - an "L" shaped hull is going to have as much problem as a ship with spin capsules.

If you go by the "hydrogen envelope" or "hydrogen bubble" model of jump drives, perhaps there might be a problem with the rotating capsules, but that depends on if the the hydrogen bubble is flexible or not. I was under the impression TNE's version of the "jump envelope" didn't need hydrogen to fill it (so that hydrogen mass is used somewhere else) and that there are "jump projectors" used to project a field around the ship to keep away warp space from the ship. In this case, I would imagine that the fields would be flexible enough so that they more or less conform to the ship's shape.

If the envelope needs to be a pre-set shape and is "rigid" (assuming again that surface area is a factor) it'd probably be generated with the spin capsules assumed to be deployed (there's little reason for them not to be considering it's a week of nothing) - if anything you might be able to get a skilled Engineer and Computer Programmer to get together and allow the ship to jump at a lower power or fuel requirement if you don't have the capsules running.

 

[aramis]

CT references only Tons, not specifying whether mass or some other unit, but providing guidance that a ton is roughly 13.5 to 14 cubic meters, and references the volume of a ton of liquid hydrogen. All drives in both core and HG use Tons.

The next edition, MegaTraveller, settles on 13.5 kl per Td (A kl is a kiloliter, which is a unit of volume identical to a cubic meter; in pure water at 4°C and 1ATM, that is also the measure of a metric ton of water...) It introduces the term displacement ton as a clarification, and specifies cargo tonnages (MT RM 51) and ship design tonnages (MT RM 61) are in displacement tons.

TNE, the third edition, settles on 14 kl per td. It also presumes 10Tm (Metric Tons, aka Megagrams) per Td for performance of thrust based drives

T4, using the same design sequences (with some additions) as TNE, uses the same definition and units.

GT uses 500cf (cubic feet), which is just a hair off. I don't recall if it accounts for mass.

T20 uses the same design system as CT, with a few additions. It specifies 14kl per Td. The mass-limit is dropped.

MGT uses a CT non-HG definition, but also explicitly gives 14kl per Td.

Throughout all of these, Jump Drives are never mass-limited, always being linked to the volume based ship tons, labeled displacement tons in MT and later. In fact, normal Maneuver drives are only mass limited in TNE and T4 (and perhaps GT... mine is packed and not accessible to check). MT has some mass-limited drives in Hard Times.

 

[atpollard]

Jump is volume based, but not shape sensitive. A 100 dTon (1400 cu. meter) needle-shaped starship and a 100 dTon (1400 cu. meter) sphere-shaped starship both use the same jump drive and jump fuel.

So go ahead and spin the ship if you want, just include the volume of the tether in the total volume of the ship (and the tether should be minimal volume - less than 0.1 dTon for most starships).

 

[Antony]

Some very interesting things brought up. I had forgotten that TNE drives used a hull grid so providing it is on the extended capsules no problem since the mass volume and price of the gear to rotate the capsules is included as part of the design process.

 

[Theophilus]

Didn't DGP's Starship Operators Manual Address Jump Fields?
Wasn't the Lanthanum used in a grid on the hull to produce a field around the ship which protected it from jump space?
Since the capsules would have a grid they would be protected from jump space.

Or some such.

 

[aramis]

DGP isn't canon (anymore). But we see such grids on the cover of one of the MT rulebooks.