Topic: Ice as ablative armour

[Chris Seal]

Hi All,

Inspired by Alistair Reynolds books, Revelation Space etc., I have started to think about relatively low-tech ships that use thick layers of ice as ablative armour for interstellar travel at speeds close to the speed of light. I am torn as to how to represent this using Spacemaster.

My gut feeling is to use the ice as an Armour Belt material and assign a DB with a gradual reduction based on travel time and or combat encounters. On the other hand, I also like the idea of representing it as in increased CAT, which again degrades with time.

The second approach has the advantage that the ship becomes increasingly more "fragile" in that it is more likely to suffer a more devastating critical, but the first approach is simpler and nominally more "in-line" with existing rules.

I was hoping I could get some feedback from more experienced heads as to the pros and cons of each approach.

Cheers
Chris

[yammahoper]

I think this sounds very playable.

First, the ice will increase AT, say +3, then2 and finally +!.  This means most ships are probably just "structures, AT 21, unless you want AT's over 23.  If the larger Mk weapons are used in the game, then a higher base AT, say 23, may be appropriate.  My thought here is a ship tough enough to profide survivability without conferring indestructability, and the higher AT require very heavy weapons to do much damage at all.

You can handle the hits two ways: as adding tototal HP or as being shot off before damage is delivered to the frame (which could allow the ship to ignore or reduce crits till the ice is shot off, increasing survivability again).  This option could allow an AT to drop "below" 21, which could be a good ship flaw (Suffering a penalty to be hit).

The above thoughts are written with the idea the Ice armor would degrade in four steps: normal/ -1 value / -2 value / -3 value.  Thus maximum bonus to AT for an Ice covering is +3.  I guess it could be much higher if desired.

[Vyrolakos]

I'm unaware of the source material, but you mention a 'relatively low tech'.

Exactly how much ice do you need to provide sufficient armour to withstand even just random interstellar debris hits at near relativistic speeds?

What kind of drives/fuel do they use and just how big are these ships?

Sounds fascinating. 

[Defendi]

I would go with armor belt, as the high CAT are super materials, but I think either would work.

[Chris Seal]

Thanks for the feedback.

I'll try the variable AT (3 steps sounds about right to me) approach and see how it goes.

@Vyrolakos - I have no idea how much ice would be needed. I'm figuring some hundreds of metres thick. The ships themselves are fairly small. Mainly engine and life support. Passengers are supported in hyperoxygenated fluid during flight and spend the time immersed in a virtual reality world. Spacers are not "real" spacers until they've "drowned" at least once. That is been immersed without the VR world.

As for tech levels, thats a little difficult. Basically in the setting the Earth looked like it was doomed so vast, high tech ark ships were built and most of the population fled through wormhole gates built at the edge of the solar system (tech level somewhere between 20 and 21).

Those left behind survived, against the odds, and have been slowly rebuilding. While people know of higher technologies, and even have records detailing much of the technology, they lack the necessary resources to further their tech level significantly. They are currently operating at a tech level of between 18 and 19.

The most common drive type is a fusion torch, operating on He3 and heavy water (which incidentaly the ice provides). They accelerate to around 0.5C and travel out to about 10 Light Years. Those that travel interstellar do so knowing that due to relativistic effects its a one way trip (in time at least ).

Hope that helps

Cheers
Chris

[Vyrolakos]

If the ice armour is only used on the interstellar ships, and journeys are once in a lifetime, one way affairs. Why do you need to stat them up?

Just use dramatic licence for whatever 'space actions' you need to occur. 

[Chris Seal]

Good question.

The overarching plot involves those who fled in the arks returning in disarray and the inhabitants of earth then fighting a war against alien invaders who've followed the returnees. Having big 'ole chunks of ice should go someway towards acting as a low tech replacement for deflector shields in the ensuing battles .

[Vyrolakos]

Sounds cool (pun intended).