AutoPistol in a Vacuum...

[vutpakdi]

So, do non-gauss projectile weapons from the Traveller universe work in a vacuum or some weird, oxygen poor atmosphere? Okay, rounds based on TL-8 or less tech probably would not, but do most rounds from TL-9 - TL-15 sources use some sort of binary propellent that doesn't require a significant source concentration of oxygen?

I'd like to assume that TL9+ (or maybe TL10+?) rounds use a binary (or more exotic) propellent that can be fired without oxygen in the outside atmosphere. What do you think?

Ron

 

[Psion]

I don't see why any firearm that later than a matchlock wouldn't work. You might have problems with gas-action chambers on some firearms if their designs assume some specific pressure differential, but for the most part shells are self-contained and don't need oxygen AFAIK. Think about your typical center-fire round. It doesn't operate on oxygen in it's environment; how could it? It's sealed. Presumably such rounds have all the oxygen they need in the shell.

 

[mike wightman]

My understanding of the chemistry of bullet propellents is that the oxidising agent is part of the explosive in the "brass" case.

The gun should fire in a vacuum the same way it should fire underwater

 

[Morte]

I would expect it to work. Evetually, accelerated evapouration of lubricants etc in the thin/absent air would increase the chances of wear and jamming. And lack of thermal conduction/convection will lead to faster overheating. But I think it would be OK for a while.

I've just told a player he couldn't use an SMG in a deep space hulk at about 20 Kelvin because (a) lubricants would freeze very quickly and jam it and (b) differential thermal contraction in the weapon would be far beyond the design envelope. It seemed plausible at the time.

 

[Morte]

Bugger, I've just realised why you're asking...

 

[vutpakdi]

Originally posted by Morte:
Bugger, I've just realised why you're asking...

Hehehe

I never thought about the sealed bullet thing. Hmmmm... Well, either way, as long as it works, that'll come in handy....

Ron

PS: For those of you confused as to why Morte just realised why I ask, the issue may have just come up in our PBEM.

 

[jasper]

did Nasa answer this. The old 20 things to take if stranded on the moon.

 

[TheBrain]

Originally posted by Ron Vutpakdi:
"So, do non-gauss projectile weapons from the Traveller universe work in a vacuum..."

According to Traveller Magazine and Mercenary yes. There quick definitve canonical answer, so it is written so shall it be done.

 

[SlightlyLyons]

The moon landing did take along pistols, I assume they expected them to work if there were little green men. In addition if modern firearm work under water I'd expect them to work in space.

 

[Uncle Bob]

I wouldn't overstate the thermal stress issues. Remember the gun is essentially in a vaccuum bottle and temperatures won't change very quickly.

Direct sunlight will be a problem in the inner system, but putting the gun in a loose bag should protect it. OTOH residual heat from firing will not radiate away very fast, so barrels will heat up quickly with automatic weapons. The first problem with heat build up will be "cook-offs" with the heat detonating cartridges in the chamber. Most SMGs are immune as they fire from an open bolt and don't chamber a cartridge until the moment of firing.

Evaporating lubricants are a problem, but contemporary pros use graphite on a dry weapon.

 

[far-trader]

Just an idea I've been kicking around for a while and finally typed up. Feedback appreciated. It is stated in T20 terms but should be adaptable to other systems.

Weapons use in vacuum

Simplistically I'd say weapons with an introduction TL of 10+ are designed to function equally well in any environmental conditions.*

*subject to interaction with the environment of course, low g extends your ballistics, flammable gases may be set off by some weapons, firing underwater messes things up, etc.

Weapons with an introduction TL of 9- are not designed to function well in extreme environments. They will breakdown if the to hit roll is less than 20 - TL* of the weapon. Just use the to hit roll, no need to make an extra roll, just a check.

*actual TL of purchase and build, not TL of intro

A breakdown renders the weapon no longer able to fire until repaired. Repairs will cost 5% the value of the weapon per each point by which the breakdown check failed.

Ammunition and power supplies with an intro TL10+ are not subject to extreme environment failure in normal use.

Ammunition and power supplies with an intro TL9- are subject to catastrophic failure if the to hit roll is less than 15 - TL*. Again just use the same to hit roll, no need to make an extra roll, just another check.

*actual TL of purchase and build

Catastrophic ammunition or power supply failure results in the full remaining ammunition being destroyed and causing damage to the shooter as a 1d1 per round remaining attack that hits automatically (no crititcal). It also does (possibly additional) damage to the weapon equal to 5% the value of the weapon per round remaining.

All of the above may be subject to situational DM's of +/-2 or more. For example if due care is taken or the environment is more or less extreme.

 

[Straybow]

Graphite lubricant depends on air molecules trapped between layers, and therefore becomes an abrasive in vaccuum.

But yes, vaccuum rated lubricants should be common in a TU. We don't spend time saying, "My character takes out his cleaning kit and strips his weapon..." We assume it is done by any reasonably trained gun owner.

 

[Vargas]

Hmmm, we just might have stumbled over a practical reason why Jayne needed to put Vera in a vacc suit in the Firefly episode 'Our Mrs. Reynolds'.

 

[Straybow]

Naw, that was a case of writers assuming guns need atmospheric oxygen to fire.

We forgive them.

 

[notagoodusername]

But yes, vaccuum rated lubricants should be common in a TU.[/QB]

Availible, but not common. Most non-military types would never come up with a reason why they would need to use a firearm in a vacumn except in the infinitessimally small chance that they are on a hijacked ship and need to go outside. Otherwise, guns are for planets and stations (and even them *most* folks who have a weapon will never need to fire it in anger ever in thier life).

Sure, the odd occasion on vacumn worlds and boarding actions will occur for players and the like, but they use vacumn lubricants because they are unusual people. So most small gunshops IMTU won't stock vac-lube, but can get it.

Shane

 

[veltyen]

Um, wouldn't vacuum rated lubricants also be needed for airlock hinges, iris locks, pressure doors arround vehicle hangars and small craft hangars and so on.

It hadn't occured to me that vac-lube would be carried for firearms, just that it would be common.

What else would all that maintenance cost of starships be spent on?

 

[notagoodusername]

True, but gun oils can be a little different than heavy engineering lubes. However, I hadn't thought of the whole airlock, etc thing. Good point.

Shane

 

[Uncle Bob]

`Mmm, IIRC the graphite particles act as roller bearings, air or no.

And I have not forgiven either Josh Whedon for not understanding his genre or the Fox executives for ****ing up a great storyline.

 

[samuelvss]

Just an idea I've been kicking around for a while and finally typed up. Feedback appreciated. It is stated in T20 terms but should be adaptable to other systems.

Weapons use in vacuum

Simplistically I'd say weapons with an introduction TL of 10+ are designed to function equally well in any environmental conditions.*

Excellent way to do this.

Big incorrect assumption in this thread: chemical propellant rounds are not impervious to vacuum unless specially treated.

The brass case of a standard (civilian) round of ammunition (TL, contains the oxidant needed to fire. It is not sealed, or "waterproof." It is, however, almost sealed, such that a sealant as primitive as nail polish will suffice. In the absence of a pressure differential, or long-term soaking, this is irrelevant. In a vacuum, though, there is a pressure differential, and standard civilian ammo's air would seep out. At pressure underwater, water seeps in, thought this may be in more than one atmosphere of pressure.

S.F. dive teams would therefore seal their ammo before diving. Most of the Soviet-compatable (7.62x39mm and 7.62x54R) stuff is sealed, despite being overall of much lesser quality.

Presumably, at TL10+ spacefaring is common enough that all ammunition is sealed (at essentially negligible expense).

 

[far-trader]

Excellent way to do this.

Thanks (for the praise, and noting the missed bit below... )

Big incorrect assumption in this thread: chemical propellant rounds are not impervious to vacuum unless specially treated.

Good point on the imperfect seal. I may have to edit my idea above to reflect the ammo simply not working if not sealed.

But I think it would be after long exposure to water before worrying. It might be more likely to be corroded before the chemicals are soaked. Or I might be wrong. Would the chemical still burn even if soaked? More slowly? Less evenly? That was kind of my thinking originally. Now I'm not sure.

Any idea on how long an exposure to vacuum would be required to render the chemical oxidizer inert? Would it? More research needed...

Presumably, at TL10+ spacefaring is common enough that all ammunition is sealed (at essentially negligible expense).

That's the easiest way to handle it