Ok, strange question. . . .

[klingsor]

Nice question, not one that had occurred to me at all.
I doubt if a radiator could get rid of the heat quickly enough.

Some weapons are purpose built for this sort of thing - Snub pistols and Accelerator rifles - so for them I would assume no penalty at all but then of course they cannot do automatic fire anyway.

Gauss. No gas, no friction, no problem.

For others?

I think I would penalise them - maybe check for a jam each turn of firing?

Looks like a good accessory - maybe it uses an innert gas to cool the barrel between shots which would increase mass - possibly of the magazine rather than the weapon though.

For some bizarre reason I am reminded of a picture I saw once of a Russian rapid firing naval gun being cooled down - by a matlot spraying it with a hose.

 

[zozotroll]

So which is it? Pete N claims it cools off to fast, but it also seems that it may heat up to fast. Cant be both.

As for test firing, I would be shocked and amazed if somebody has not already fired a few rounds. Most likely the USA and the USSR both did it at some time, probably pretty early on.

 

[Mongoose Pete]

So which is it? Pete N claims it cools off to fast, but it also seems that it may heat up to fast. Cant be both.

It will all depend on the ambient temperature of the weapon at the time of firing. If you've been drifting around in space for fifteen minutes then that barrel will initially start off seriously sub zero (*) - one shot and there's a good chance of a jam, or even the barrel warping/fracturing due to heat stress ($).

If you jump straight out the airlock with your still warm gun and blast away, the weapon may start off fine heat wise but then (as someone previously pointed out) you'll get the opposite effect, that the barrel won't cool down very quickly - possibly leading to some nasty accidents, and incidentally making you a nice juicy IR target.

Solid lumps of mass cool slowly in space, whereas small particulate matter freezes very quickly. The difficulty lies in predicting how the two will interact - discharged propellant versus gun barrel. Either way, you should still see some pretty frozen gases flying around, and if you're really unlucky, condensing on your faceplate (#).

Just for an example of the rapidity of condensation (freezing) in a vacuum here's a quote from Physics of Shock Waves and High-Temperature Hydrodynamic Phenomena...

We present here the results of some rough estimates for conditions close to those encountered in the laboratory. If we rapidly vaporize 1g of iron by transferring to it in some manner an initial energy of 13 ev/atom, corresponding to the initial temperature (at the density of solid metal) of 35,000 degrees Kelvin, then the condensation of the vapour in a sudden expansion into vacuum end at the time t=5x10(to the -5) seconds, when the cloud has expanded to 30cm

Which is well within the length of a sub machine gun barrel. When you take into account this example is using iron, rather than a combination of nitrous and oxygen based materials with far less heat capacity, that it assumes a vacuum at room temperature, and that the initial vaporisation temperature far exceeds that of propellant ignition, you can see that an expanding cloud of firearm propellant in space will freeze extremely quickly, even within the briefly pressurized barrel!

Pete

(*) Difficult to specify accurately - how close are you to the main star? What type is it? Are you in shadow? How good is the heat insulation on your suit? How good is the vacuum surrounding you? Are you next to the cooling engines? Etc.

($) Depending on the material used, quality of manufacture, etc.

(#) As anyone who's experienced cross country skiing wearing glasses at -25 Celsius will readily confirm, let alone the ice buildup on your beard...[/quote]

 

[zozotroll]

Never skied in subzero weather, but I have worked cannon in those conditions fron time to time, and understand some of the problems.

Some of the problems you face in the field are increased bore, and small holes getting plugged up.

As metal heats up it expands, which causes the bore to constrict, which ups preassure, but also velocity. As it cools down it contracts, and loses velocity. On the big guns, you can certainly loses enough to effect accuracy. I suspect, but dont know for sure this is also a problem on smallarms.

fouling a barrel is no big deal in the short run. Over time it can be a problem, but on modern guns you have bigger worrys sooner. One of these is that most if not all modern rifles use a gas bleed off system of some kind that uses propellent energy to make the action cycle. Those work off of very small holes that are prone to plugging up with very little effort, which stops the weapon in its tracks. If you have propellent residue freezing, that is going to acelerate that particular problem.

I also suspect that unless you windshield wipers on your faceplate, it is going to get obscured fast as well.Probably need some sort of solvent as well.

Perhaps thats why they keep cutlasses. But then dont most metals shatter easily at very low temps? Hey, why not lead maces? Go Zorak Zoran!!

 

[Woas]

Interesting thoughts so far. In the interest in having fun I've ruled that guns are ok in vacuum despite the heat problem, claiming non-guilty to the Laws of Science by my Right of Handwavium. I figured in the future, with the near limitless resources of a whole galaxy worth of material, new compounds probably were developed to handle these problems. Or at least mitigate them to an extent that the problem would not be an issue in the time frame of a single 'adventure'. Easy answer and keeps the players happy. :wink:

 

[Dave Chase]

Interesting thoughts so far. In the interest in having fun I've ruled that guns are ok in vacuum despite the heat problem, claiming non-guilty to the Laws of Science by my Right of Handwavium. I figured in the future, with the near limitless resources of a whole galaxy worth of material, new compounds probably were developed to handle these problems. Or at least mitigate them to an extent that the problem would not be an issue in the time frame of a single 'adventure'. Easy answer and keeps the players happy. :wink:

Hmm, that makes me think abit

How about a general rule of TL/3 rounded down is the number of shots a firearm could do in a vaccum before malfunction (or before you roll for malfucntion)? That might make it more interesting instead of just saying they work

Dave Chase

 

[Woas]

Interesting you mention (great minds, as they say... ) that because the idea of giving guns some sort of malfunction 'limit' was something I had also thought of. The reason being that by allowing all guns to fire in a vacuum without err then what is the benefit/purpose of accelerator rifles and snub pistols?

Honestly thus far the characters have probably fired their guns a dozen times in vacuum, and all of those times have been relatively spaced apart so the real nitty-gritty of the issue hasn't reared its head and the overall 'it works' answer has been acceptable. But when the situation occurs that a PC unloads a full clip from his assault rifle over the course of 2 or 3 combat rounds... well then there is probably going to be a problem and require some sort of malfunction check.

The actual malfunction check hasn't really gone past nebulous brainstorming for me, as like I mentioned it hasn't really warranted more thought than that. But initially I was thinking off a loose system where if a character fired a full clips worth of ammo appropriate to the weapon used within a certain time frame (probably measured in minutes... 5 mins maybe?) then a malfunction check would occur until you successfully cooled the gun (didn't fire it for X minutes or bring back on a ship with an artificial atmosphere and let it cool...). Special barrel radiator attachments or removable/disposable heat sinks could be purchased as special add on gear (like laser sights, under barrel 'nade launcher, etc.) to increase or even negate the problem if excessive vacuum firing was foreseen.

As for the actual malfunction check I'm not sure what exactly would happen. Just a flat 2d6 or maybe come up with a special/more specific Malfunction chart that uses 66% and glue it to the back cover of my book...

Hmm, that makes me think abit

How about a general rule of TL/3 rounded down is the number of shots a firearm could do in a vaccum before malfunction (or before you roll for malfucntion)? That might make it more interesting instead of just saying they work

Dave Chase

 

[Dave Chase]

OK, Woas, I will raise your brain storming by one idea.

Heater/cooler units for firearms.

Ever seen those 12v coolers that use thermal with a small fan. One way they heat the other way they cool.

For vaccum instead of a fan they use the same principal as an airconditioner/radiator. It will allow X amount of additional time of weapon use. Exspensive addition as compared to just buying a weapon designed for vaccum/hot worlds but then it still allows you to use your favorite weapon (or basically the weapon that you are skilled in.)

Hmm, I like this my self. Thanks for the prod. Of course the above is just the initial though and not a final product. Adjustments are welcome.

Dave Chase

 

[Zemekis]

The reason being that by allowing all guns to fire in a vacuum without err then what is the benefit/purpose of accelerator rifles and snub pistols?

Firing a gun in zero-G or low-G environment will throw the character off balance/course. It will take him several rounds to stabilize again. That's where the accelerator rifles come in.

 

[Woas]

I think I got this link from these forums but cannot remember who posted it. But apparently from the information presented by this site: http://www.projectrho.com/rocket/index.html (specifically under the Sidearms Topic - Slugthrower Section) that recoil from a weapon is not all that debilitating. Although the website doesn't go into specifics with firing an assault rifle on burst/auto mode.

I guess something to think about. I suppose some sort of recoil reversal gyroscope could be devised to mitigate most of the problem if you want to throw that in with the rest of the hand waving.:wink:

Firing a gun in zero-G or low-G environment will throw the character off balance/course. It will take him several rounds to stabilize again. That's where the accelerator rifles come in.

While painting a bookshelf ealier and having read your addon to the idea Dave Chase I thought of some neat 'vacuum' gear for firearms:

First is a disposable thermal paste/grease. Comes in small tubes (or even in bulk tubs if you are dedicated enough) that you apply to the barrel of your firearm. The paste absorbs the heat from the gun and eventually degrades/evaporates after it absorbs a certain amount of heat and requires reapplication.

Second is taking the first to the next level. Thermal paste actually just allows heat sinks to work better since it replaces air that might normally be between a heat source and heat sink, and make a better contact. So you smear some thermal paste on the barrel of the firearm and then snap on some heat sinks. The heat sinks absorb the heat from the barrel. Once the heat sinks reach an equilibrium with the barrel and cannot absorb anymore heat you hit a quick release (as you probably wouldn't want to touch them. Ouch!) and they fall/float away from the barrel so that you can put a new set of disposable heat sinks on.

 

[BP]

Some good points have been made here..

What hasn't been touched on is explosive out-gassing - when the gasses trapped in materials (especially polymers, powders and lubricants) violently try to leave their host materials at various rates due to extreme vacuum!

Ironically, modern weapons may have more problems versus older lower-tech (bulk metal) ones that might last a round or more. The biggest problem might be the ammunition - it may very well come apart. While unlikely to cause direct damage to the bearer, the weapon would be useless excepting projectile and club uses (accounting for low-gee if applicable).

P.S. - my dad heads a vacuum lab and fabs payloads for NASA and ESA probes - comets, the moon, Sol, Mars, Saturn, Jupiter and 'soon' Pluto and Kuiper Belt - this makes me no expert, but he has enlightened me on many common materials that can't go into hard vacuum.

 

[BP]

Also, I am thinking (ouch) that most weapons and other equipment even in high tech environs would not by default be designed for vacuum - excepting belter communities, of course.

Most space combat would be between ships and not soldiers and the majority of the population, even in Traveller, is planet based. Thus handling the extremes of vacuum is not likely to be required for most items (i.e. increased cost and marginal market) – especially propellant based weapons.

Weapon weight is critical to usability in so many ways – so exotic materials like foamed metals and aerogels are likely to be used – materials my last post pointed out would likely tear themselves apart with vacuum exposure (and faster than they can be drawn/fired).

In play, I would give only a marginal chance of success with a firearm in a vacuum – and then only seconds after exposure and with targeting and damage losses in low/zero G. Not to mention rendering the weapon permanently useless.

An interesting advantage (or evil Referee twist), would be that without atmo friction, bullets will have extreme ranges, with gravity wells proving interesting paths.

 

[rust]

Also, I am thinking (ouch) that most weapons and other equipment even in high tech environs would not by default be designed for vacuum - excepting belter communities, of course.

Plus each and every piece of equipment that is expected to be transpor-
ted through jump space in a non-pressurized cargo hold.

 

[klingsor]

Good thoughts, the end user is critical so Marines and Navy would want vacuum capable weapons but the army less so. I am of course assuming that the Imperial armed services do standardise weapons - so a Marines rifle is the Marches is the same as the one in Sol?

The army might be different but personally I would standardise on vacuum capable weapons - ideally common ones across all the armed services - with local forces encouraged to standardise on them as well - or at least ones with compatible ammunition and magazines like NATO which, in theory at least, have common ammunition and magazine types so that a British grunt can scrounge magazines off his American ally (no change there then).

A slightly weird example was a British squaddie who started off a battle in the Falklands War with 20 magazines for his SLR (British version of the FN FAL) who finished it scrounging for magazines from the Argentinian dead who used a different version of the FAL.

I remember seeing a picture that illustrated how NASA modified the cameras they took to the moon, it included removing a lot of materials that were not vacuum friendly.

 

[barasawa]

As tech levels go up, the materials and components in the weapons become more capable. By the time you reach Imperium level reproductions (TL11+) it's very unlikely that they won't function properly in a vacuum. Too many customer complaints otherwise, especially from legal purchasers. (military, mercs, security, etc). Besides, no manufacturer is going to waste money getting some old petroleum lubricant that is likely to cause jams when a modern nanopolymer coating is cheaper, more effective, and won't jam in a vacuum based firefight.

It basically boils down to this:
Low TL produced gear may have problems in a vacuum situation.
High TL produced gear won't, even if the end product is from a lower TL.
Don't beat your players over the head with "real world" stuff, just use it as the occasional hook or plot complication.

 

[BP]

Plus each and every piece of equipment that is expected to be transpor-
ted through jump space in a non-pressurized cargo hold.

Hmm... most deckplans won't be amenable to non-pressurized cargo holds (engineering, staterooms inaccessible during jump) - plus the disadvantage of pressurizing a hold when docking with high ports. When looking at trade – most goods would require pressurized containers at the very least to survive a vacuum (partial atmo would be ok).

Excuse my ignorance - I do not have my Mongoose books yet (hurry up USPS) – and only have ever had the CT books – is this stated somewhere in CT or MGT OTU? My impression was that most Traveller ships did not handle decompression well excepting Military (and Criminal) that were designed to decompress before engagements.

 

[BP]

As tech levels go up, the materials and components in the weapons become more capable. By the time you reach Imperium level reproductions (TL11+) it's very unlikely that they won't function properly in a vacuum.

Assuredly, but the post seemed to be about firearms – specifically ballistic – I think everyone assumes lasers work in space (I assume the assumption <grin>). Lasers start at Tech-8 in CT. A Tech-11 rifle might be designed for vacuum, but at that tech level may be unusual (and still basically reflect Tech-6 mentality – i.e. not designed for space combat).

 

[rust]

If you take a look at the Heavy Freighter from the Mongoose Traveller
core book, it looks very much like a craft designed for non-pressurized
cargo holds - it even has an airlock and a vacc suit storage between
the crew compartment and the cargo holds.

 

[BP]

Argh - no book yet (ETA is 6th)!

Yeah - I design my ships to allow for decompression by area (cargo included) - but most don't seem to be. I just never assumed cargo hold would be decompressurized except when picking up/dropping (or dumping) as needed - or resulting from attack.

So rust - you were not quoting cannon then... just checking so I can avoid showing off my ignorance.

Thanks.

 

[rust]

So rust - you were not quoting cannon then... just checking so I can avoid showing off my ignorance.

Rest assured that I would never quote canon, I am a heretic. :lol: