Space Combat Hit Location.

Discuss the Traveller RPG and its many settings
Old School
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Re: Space Combat Hit Location.

Postby Old School » Sat Dec 15, 2018 7:45 pm

No doubt in combat you’re wearing a vacc suit. Higher tech vaccsuits are light enough to provide no restrictions on mobility. Most provide some armor protection, as well as radiation protection.
Moppy
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Re: Space Combat Hit Location.

Postby Moppy » Sat Dec 15, 2018 10:22 pm

Fuel in zero-g will probably just float around in a ball being chill. I wonder if they can use the internal artificial gravity to keep it in a holed tank?
Condottiere
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Re: Space Combat Hit Location.

Postby Condottiere » Sun Dec 16, 2018 12:21 am

If you spent default fifty thousand schmuckers per tonne, than your tanks should be fitted for artificial gravity.
phavoc
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Re: Space Combat Hit Location.

Postby phavoc » Sun Dec 16, 2018 4:45 am

Condottiere wrote:
Sun Dec 16, 2018 12:21 am
If you spent default fifty thousand schmuckers per tonne, than your tanks should be fitted for artificial gravity.
Nah. There's no need for AG in the tanks. However the rules surrounding ship board AG have never been fully explained. Just how far does the field go? Is it limited to exclusively being deck-plating only? Can you alter the fields deck by deck, so floors become ceilings, and ceilings become floors? How far to the fields extend? In theory, if it's deck-plating only, then access ladders are zero-g areas. And what about the field extending beyond the hull? If it's not then anybody on the outside is subjected to the normal effects of gravity - more than 1G of thrust, radical hull spin could make the vomit-comet training seem like a cakewalk.

Lots of questions...
Sigtrygg
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Re: Space Combat Hit Location.

Postby Sigtrygg » Sun Dec 16, 2018 10:04 am

There is a need for artificial gravity and acceleration compensation in the fuel tanks.

If you are pulling twenty plus g maneuvers during combat or reentry you do not want all that mass shifting unexpectedly.

And most of your questions have been answered in CT sources...
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Re: Space Combat Hit Location.

Postby Moppy » Sun Dec 16, 2018 12:20 pm

I always see that the fuel is "L-Hyd" or liquid hydrogen.

Why is the fuel even liquid in the tank, instead of solid?

Hydrogen freezes around -260 C is liquid for about 8 C between -260 and -252, and turns to gas at about -252. I know, exponentially harder to get closer to absolute zero, but TL 12 is magic.

Seems just easier to have it as a solid. No sloshing around, no leaks, and melt it as required to go into the reactor.
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Re: Space Combat Hit Location.

Postby phavoc » Sun Dec 16, 2018 1:50 pm

Sigtrygg wrote:
Sun Dec 16, 2018 10:04 am
There is a need for artificial gravity and acceleration compensation in the fuel tanks.

If you are pulling twenty plus g maneuvers during combat or reentry you do not want all that mass shifting unexpectedly.

And most of your questions have been answered in CT sources...
Spacecraft work just fine today without anti gravity in their fuel tanks. There are things called baffles that are used today to minimize sloshing.

And that's not an issue in Traveller ships. Of course it used to be that 6G was the upper limit in CT as well.

Since we are speaking of CT, that's a different set of rules and paradigms. Is it something that carried over through all the various versions? Was it rendered moot by changes, published or not? This has been an inherent problem with versions since the first. What remains Canon or not if you don't explicitly call it out? And what if the original rule was already in conflict with something else? This is why people buy games rather than make their own up, to have professionals go through all the headaches of consistency. And it's why we have such huge errata these days, too.
Moppy wrote:
Sun Dec 16, 2018 12:20 pm
I always see that the fuel is "L-Hyd" or liquid hydrogen.

Why is the fuel even liquid in the tank, instead of solid?

Hydrogen freezes around -260 C is liquid for about 8 C between -260 and -252, and turns to gas at about -252. I know, exponentially harder to get closer to absolute zero, but TL 12 is magic.

Seems just easier to have it as a solid. No sloshing around, no leaks, and melt it as required to go into the reactor.
You need it in liquid for to pump it. You can store it as a solid, there's a rule for that floating around somewhere.

The antigrav field renders a lot of problems moot. But then it also doesn't cover new holes rendered moot. It used to be you had to capture a ship with no mobility capabilities. People tend to forget the physics of being in space. Without an antigrav field you are subject to all the stresses of acceleration. The rules talk of being able to control individual grav plating, so an intruder could be subjected to high low grav cycling, depending on what the plates can do. External intruders could be subjected to 20g worth of grav because that's a capability today with high burn thrusters.

So do grav belts counter that high of a field? Or can you kill raiders as long as you have power?
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Re: Space Combat Hit Location.

Postby Reynard » Sun Dec 16, 2018 2:09 pm

The Armored Bulkhead option should be used for critical sections of a ship such as medical bays that can't be depressurized in combat.
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Re: Space Combat Hit Location.

Postby AnotherDilbert » Sun Dec 16, 2018 2:15 pm

IIRC, MT specified that artificial grav and inertial comp must be installed for the entire hull.
Moppy wrote: Why is the fuel even liquid in the tank, instead of solid?
Because no-one had bothered to consider it?

Note that not only temperature, but also pressure is needed to keep the hydrogen solid. If the tanks are compromised the fuel would gasify anyway?
Condottiere
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Re: Space Combat Hit Location.

Postby Condottiere » Sun Dec 16, 2018 4:14 pm

Increased gravity increases pressure.
AnotherDilbert
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Re: Space Combat Hit Location.

Postby AnotherDilbert » Sun Dec 16, 2018 10:41 pm

Condottiere wrote: Increased gravity increases pressure.
Yes, at the "bottom" of the pile, not at the "top" of the pile.

The parts of the solidified fuel exposed to vacuum would still gasify.
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Re: Space Combat Hit Location.

Postby Moppy » Mon Dec 17, 2018 12:11 am

AnotherDilbert wrote:
Sun Dec 16, 2018 10:41 pm
Condottiere wrote: Increased gravity increases pressure.
Yes, at the "bottom" of the pile, not at the "top" of the pile.

The parts of the solidified fuel exposed to vacuum would still gasify.
Why would it gasify? Assuming it stays cold, of course.

Also it's not lighter than air anymore since there's no air. Artificial grav will pull it down through the vacuum.

Out of all the ways of storing hydrogen they chose, liquid feels kind of low tech. Maybe shrink-wrapped pellets, or maybe combine it with something else to make it spongify, or whatever. Anyway, what's been done has been done :-)
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Re: Space Combat Hit Location.

Postby paltrysum » Mon Dec 17, 2018 12:33 am

phavoc wrote:
Sat Dec 15, 2018 4:29 pm
While the rule book says that uniforms can be space suits, the writer didn't quite know what they were talking about. A space suit has to be airtight, thus your uniform would not breathe. A person would overheat and sweat a lot. And it would be very uncomfortable and not very practical.
In fairness we have no idea what TL12-15 materials technology might have in store for denizens of the future. There could be light but durable materials that breathe when they're supposed to, and keep the air sealed in when they're not. I'm sure TL5 Terran humans thought it was preposterous that you would eventually be able to speak in virtual real time to a 2D image, held in your hand, of your relative or friend on the other side of the planet yet here we are.
"Spacers lead a sedentary life. They live at home, and their home is always with them—their starship, and so is their country—the depths of space."
Old School
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Re: Space Combat Hit Location.

Postby Old School » Mon Dec 17, 2018 12:52 am

I prefer just to play the game and not worry so mich about these things.
AnotherDilbert
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Re: Space Combat Hit Location.

Postby AnotherDilbert » Mon Dec 17, 2018 12:55 am

Moppy wrote: Why would it gasify? Assuming it stays cold, of course.
I'm a bit out of my depth here, but:

Phase diagram for hydrogen:
Image
https://lcn.people.uic.edu/classes/che2 ... ng_02a.pdf
Up and down is pressure difference.
Left and right is temperature difference.

OK, if we can keep the H below ~5 K it should stay put, but that would be difficult if the tank is compromised. If we increase the gravity the material should compress releasing a little potential energy and heat up.

In vacuum, the top of the material and any surface layer exposed to vacuum will not be under pressure, so move straight down in the diagram above. If it crosses a phase line it will start to convert, releasing or binding energy (temperature).

So, if we keep the H solid under atmospheric pressure at 10 K, and then crack the tank exposing the solid to vacuum and the far higher temperatures outside the tank, the pressure will plummet and it will start to heat up, moving straight down and a little to the right in the diagram, from solid toward gas, possibly via liquid phase.

Yes, gravity will pull the released gas molecules down, but they will bounce around and a little gravity is weaker than molecules crashing into each other. Effectively the gas will try to fill the vacuum, escaping the tank.
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Re: Space Combat Hit Location.

Postby Condottiere » Mon Dec 17, 2018 8:17 am

Image

Cotton breathes.


Image

Gravitational plating is usually tiled.
phavoc
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Re: Space Combat Hit Location.

Postby phavoc » Mon Dec 17, 2018 1:12 pm

paltrysum wrote:
Mon Dec 17, 2018 12:33 am
phavoc wrote:
Sat Dec 15, 2018 4:29 pm
While the rule book says that uniforms can be space suits, the writer didn't quite know what they were talking about. A space suit has to be airtight, thus your uniform would not breathe. A person would overheat and sweat a lot. And it would be very uncomfortable and not very practical.
In fairness we have no idea what TL12-15 materials technology might have in store for denizens of the future. There could be light but durable materials that breathe when they're supposed to, and keep the air sealed in when they're not. I'm sure TL5 Terran humans thought it was preposterous that you would eventually be able to speak in virtual real time to a 2D image, held in your hand, of your relative or friend on the other side of the planet yet here we are.
I'm not saying it's not possible. What I'm arguing is that it's not practical. Space is an unforgiving environment. And I'd argue that the illustrations provided to us in all the versions show space suits as still being suits.

Magical fibers aside, it's got to provide a modicum of protection against space environment, not just a vacuum. And, above all, it's clothes you wear all the time, ergo it needs to be comfortable and practical. When you add all these things together it makes it quite improbable.

Which it's why it's just plain easier to drop the notion your uniform is a spacesuit.
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Re: Space Combat Hit Location.

Postby Moppy » Mon Dec 17, 2018 2:36 pm

phavoc wrote:
Mon Dec 17, 2018 1:12 pm

I'm not saying it's not possible. What I'm arguing is that it's not practical. Space is an unforgiving environment. And I'd argue that the illustrations provided to us in all the versions show space suits as still being suits.

Magical fibers aside, it's got to provide a modicum of protection against space environment, not just a vacuum. And, above all, it's clothes you wear all the time, ergo it needs to be comfortable and practical. When you add all these things together it makes it quite improbable.

Which it's why it's just plain easier to drop the notion your uniform is a spacesuit.
Today's space suits weigh over 100 kilos (220+ lbs). Traveller vacc suit is what, 10 kilos? There's some very significant advances there. It's lighter than the stuff ~~soldiers~~ infantry carry around with them all day.

The main argument I see isn't weight, but overheating, and visors fogging up, maybe fat-finger the controls etc.

When your ship is pressurised, you don't wear the helmet - or the visor is open?

When the GQ sounds, you put on the helmet, or close the visor, and maybe the oxygen tank if it needs one. Ships aren't at GQ for long. A phone can work with thick gloves if you program it with that mode in mind.

When not at GQ, given advances in cooling (turn up the ship's aircon? install a fan in the suit?) I can't see it being that bad at high TL.

edit: I think I prefer the "visor and cooling flaps are open" and when you press a button or the air pressure drops, they auto-shut.
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Re: Space Combat Hit Location.

Postby phavoc » Mon Dec 17, 2018 3:11 pm

Moppy wrote:
Mon Dec 17, 2018 2:36 pm
Today's space suits weigh over 100 kilos (220+ lbs). Traveller vacc suit is what, 10 kilos? There's some very significant advances there. It's lighter than the stuff ~~soldiers~~ infantry carry around with them all day.

The main argument I see isn't weight, but overheating, and visors fogging up, maybe fat-finger the controls etc.

When your ship is pressurised, you don't wear the helmet - or the visor is open?

When the GQ sounds, you put on the helmet, or close the visor, and maybe the oxygen tank if it needs one. Ships aren't at GQ for long. A phone can work with thick gloves if you program it with that mode in mind.

When not at GQ, given advances in cooling (turn up the ship's aircon? install a fan in the suit?) I can't see it being that bad at high TL.

edit: I think I prefer the "visor and cooling flaps are open" and when you press a button or the air pressure drops, they auto-shut.
I agree future suits should be much lighter. But todays' suits provide thermal protection and radiation protection as well as atmospheric recirculation. That's a lot to ask from a jumpsuit.

A ship may take hits and your suit needs to protect your for many hours while you work to patch holes and get pressure back online. Or if you have to go outside and make repairs.

I still think it's easier to keep space suits and clothes separate.
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Re: Space Combat Hit Location.

Postby paltrysum » Mon Dec 17, 2018 3:41 pm

phavoc wrote:
Mon Dec 17, 2018 1:12 pm
Magical fibers aside, it's got to provide a modicum of protection against space environment, not just a vacuum. And, above all, it's clothes you wear all the time, ergo it needs to be comfortable and practical. When you add all these things together it makes it quite improbable.

Which it's why it's just plain easier to drop the notion your uniform is a spacesuit.
Good argument. I prefer it your way quite frankly.
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