B5 Firearms Question

[Balrog]

I've been watching the series from the beginning, and one thing I've noticed are EA weapons that I've forgotten. Most times they're just variations on the PPG, but one of them doesn't look it. It's rifle-size but has a stubbier, wider barrel then normal PPGs, and it has a magazine which look like it contains large shells, i.e. grenades. You can see Security personnel carrying them in "The Long, Twilight Struggle" and "Point of No Return." Does anyone know what exactly this weapon is?

[NecronLord]

I figured, as they were preparing for riots, it was a tear (or 'Morph') gas launcher.

[Balrog]

I figured, as they were preparing for riots, it was a tear (or 'Morph') gas launcher.

I thought that too, but want to be sure. If that's the case, they could probably fit it with different grenade types, like frag, right?

[Uraniun235]

I figured, as they were preparing for riots, it was a tear (or 'Morph') gas launcher.

I thought that too, but want to be sure. If that's the case, they could probably fit it with different grenade types, like frag, right?

Maybe, although given that the weird rationale for the PPG was that it wouldn't puncture the hull (as opposed to bullets) it doesn't seem likely they'd be employed on-station.

[Kojiro]

Is this the weapon you're referring to?

[Balrog]

Yes, actually. Odd, it looked nothing like a PPG, and I don't recall it ever firing plasma blasts. Oh well.

[Rye]

I figured, as they were preparing for riots, it was a tear (or 'Morph') gas launcher.

I thought that too, but want to be sure. If that's the case, they could probably fit it with different grenade types, like frag, right?

Maybe, although given that the weird rationale for the PPG was that it wouldn't puncture the hull (as opposed to bullets) it doesn't seem likely they'd be employed on-station.

That is a weird rationale, since you would've thought that ricochets would be a more pressing problem for firing guns in enormous enclosed rotating metal superstructures, rather than going through the walls, especially since ppg rifles shoot through metal doors in the episode where they use the telepaths to disable the EA ships.

[Balrog]

If this necro is inappropriate, split/lock as you see fit.

While rewatching the series I came across this quote. It's Dr. Franklin's autopsy report of a dead human Ranger killed by a PPG pistol:

Dr. Franklin: Well, a single shot from a PPG at close range directly to the heart. Superheated helium tore through his rib cage, incinerated most of his heart and fused the 15th and 16th vertebrae.

How powerful would the PPG blast have to be to cause that level of damage?

[Eris]

Dr. Franklin: Well, a single shot from a PPG at close range directly to the heart. Superheated helium tore through his rib cage, incinerated most of his heart and fused the 15th and 16th vertebrae.

How powerful would the PPG blast have to be to cause that level of damage?

That's extremely hard to say, partly because it's pretty vague on the actual severity of the damage, and due to the rather exteme variability in the resistence of various tissue types. As an extreme generalisation, you could say it has to be more powerful than our most heavy duty of small arms ammunition (so 4 kJ as am extreme lower threshhold), but I couldn't say for sure what the reasonable upper bound is.

However, there's a more serious problem than just vagueness, and that's how does applied heat cause vertebral fusion? Heat tends to cause bone destruction, not bone formation.

[Anguirus]

^ I guess the idea is that it melted the bone together, but it's probably just inaccurate.

[Teleros]

However, there's a more serious problem than just vagueness, and that's how does applied heat cause vertebral fusion? Heat tends to cause bone destruction, not bone formation.

A few ideas off the top of my head:
1. It didn't literally fuse the vertebrae, but locked them together somehow (shrapnel from the rib cage, heating / expanding the cartilage or something). Conflicts with Franklin's report however.
2. It missed / glanced the spine, and some of the heat given off caused this. Doesn't explain how the body survived though, because you'd need a hell of a lot of energy for this.
3. It missed the spine, but the heat remaining in the body caused the fusing. Same problem as (2).

[Alan Bolte]

Clearly in the B5 universe spines are made out of metal.

[phred]

nah he just had too much iron in his blood

[Connor MacLeod]

Dr. Franklin: Well, a single shot from a PPG at close range directly to the heart. Superheated helium tore through his rib cage, incinerated most of his heart and fused the 15th and 16th vertebrae.

How powerful would the PPG blast have to be to cause that level of damage?

That's extremely hard to say, partly because it's pretty vague on the actual severity of the damage, and due to the rather exteme variability in the resistence of various tissue types. As an extreme generalisation, you could say it has to be more powerful than our most heavy duty of small arms ammunition (so 4 kJ as am extreme lower threshhold), but I couldn't say for sure what the reasonable upper bound is.

Bullets generally rely on mechanical rather than thermal effects to inflict damage, however, so that's not really all that good a comparison. Bullets rely on crushing and tearing tissues during their passage through the body, and that's a function as much of force/mometum as it is KE. Its also a function of how the bullet itneracts with the body (hollowpoints make larger holes, as do bullets that tumble or fragment, than if it just "shoots through", for example. Fragmenting bullets, or bullets like the Glaser saftey slug or a shotugn blast, can make quite *large* holes even with a few kilojoules (or less) of energy.)

On the other hand, 3-4 kilojoules of energy is barely enough to raise 1 kg of water by one degree - and the human body is 70% water.

It says that "most" of the heart is incinerated, which means cremation/reduced to ashes (basically). An average (adult) human heart is around 400 grams in mass IIRC, so we can guess at least 200 grams (Half the heart) is affected, but somewhere less than the whole (300-350 grams, say)

The requisite temps for cremation generally go around 1000-1200K and the specific heat of human tissue is around 3-3.5 kilojoules per kg*K. Incidentally, that's roughly the same amount of energy as needed to vaporize water at body temperature, so we also don't need to account for that.

To completely incinerate a 400 gram heart will require at least a megajoule of energy, so we can guess that the PPG blast as noted above possessed at least between 500 kilojoules and 1 megajoule of energy, ignoring inefficiencies and the energy involved in penetration of the flesh and ribs. (Damage to the vertebrae could be considered "secondary" effects, as I outline below.)

However, there's a more serious problem than just vagueness, and that's how does applied heat cause vertebral fusion? Heat tends to cause bone destruction, not bone formation.

Actually high temperatreus will probably just cause the component materials of bone to decompose into their constituent elements (you can burn bone at high enough temperatures, but even a cremation oven can't completely destroy bone) Perhaps

Alternately, the shot probably releases enough thermal energy (at least it would if any cremation/incineration occurs, as per above) to cauterize much of the wound internally (the absence of blood supports this) Its possible enough soft tissue is fused together around the bone to achieve this - I should point out there ARe cushioning pads between the vertebrae - I imagine those could be "fused" rather than the bones.

[Darth Wong]

The larger problem would be explaining why PPG shots do so much damage as discovered after the fact, but fail to do anywhere near that much damage when we see them hitting living people. And I'm not just talking about glancing shots not doing much damage; I'm talking about all of the shots. Have we ever seen a PPG shot incinerate a fist-sized chunk out of a man's chest when it hits him?

For that matter, why would this shot do so much damage to his heart, but not blast a huge crater out of his chest on the way in? Is it some kind of shell with a delayed-action fuse?

[Connor MacLeod]

The larger problem would be explaining why PPG shots do so much damage as discovered after the fact, but fail to do anywhere near that much damage when we see them hitting living people. And I'm not just talking about glancing shots not doing much damage; I'm talking about all of the shots. Have we ever seen a PPG shot incinerate a fist-sized chunk out of a man's chest when it hits him?

For that matter, why would this shot do so much damage to his heart, but not blast a huge crater out of his chest on the way in? Is it some kind of shell with a delayed-action fuse?

Mike, we're talking about a wepaon that is supposed to be firing "superheated helium" subsonic pulses that never drop in gravity. The absence of visual effects is the least of the problems. (at least that can be reconciled perhaps by body armour in some cases, or variable outputs.) Treating it as some sort of "fused projectile" probably makes more senes than treating it as some sort of "plasma energy weapon", given the other attributes. And there is other evidence that "glowy pulses" actaully are projectiles or "projectile like" weapons (both for capital ships and smaller-scale ones.)

Though the lack of drop in gravity is still downright bizarre.

Edit: Also, I'm just going by the text above. I dont remember if we actually see the body or not in the episode, so its possible the visuals may or may not mesh with what we see above. And I AM assuming we treat "incinerate" literally. It could just as well mean "burn very badly"

Which would still be fairly energy intensive (about double digit KJ or maybe low triple), but well below cremation levels.

[Connor MacLeod]

I would also note that some of these gripes have applied to blaster weapons in Star Wars as well (as in "how a bolt can make a small hole like that and yet injure/kill someone.) Nevermind "cutting through blast doors with triple digit megajoule" ligthsabers

[Darth Wong]

Though the lack of drop in gravity is still downright bizarre.

If the EA had the kind of ultra-cheap ultra-common anti-grav technology that we see in SW, it might be explained by assuming that there is some kind of antigrav built into the projectile. Since they don't appear to have anti-grav technology at all (at least not until after the Shadow War), this doesn't work.

It could just as well mean "burn very badly"

That would make more sense, unless the guy's torso flared up like some of the Death Star guards in the original ANH.

[Connor MacLeod]

If the EA had the kind of ultra-cheap ultra-common anti-grav technology that we see in SW, it might be explained by assuming that there is some kind of antigrav built into the projectile. Since they don't appear to have anti-grav technology at all (at least not until after the Shadow War), this doesn't work.

Unless you're a rabid Fiver retard like Adarx They'd just take it as proof of how "advanced" EA's AG tech is (They'd just pretend its not really "artificial gravity" in some semantics wanking.)

Best guess I can make is that its some sort of tracer, like with STar Wars *shrug*

It could just as well mean "burn very badly"

That would make more sense, unless the guy's torso flared up like some of the Death Star guards in the original ANH.[/quote]

Actually we dont see that "flare up" all that often, and I'm not sure its what we'd see. I'm pretty sure blasters ought to be putting holes in a person's body (the body is 70% water after all... and penetrating the torso to reach vitals is going to mean some sort of explosive effects, unless the weapon delivers the energy in a very particular way.)

Of course, we DO hear of blasters doing big, messy holes like that in the novels and stuff, so I usually attribute the lack of this in the movies to the presence of body armor. (I always thought it would be pretty stupid for the Death STar troopers and officers to go around unarmored.)

[Balrog]

Edit: Also, I'm just going by the text above. I dont remember if we actually see the body or not in the episode, so its possible the visuals may or may not mesh with what we see above. And I AM assuming we treat "incinerate" literally. It could just as well mean "burn very badly"

Can't do screencaps, but we do see the body, there's basically a fist-sized hole over where his heart is scorched black.

[Connor MacLeod]

Can't do screencaps, but we do see the body, there's basically a fist-sized hole over where his heart is scorched black.

Cauterization maybe. I dont think it would neccearily incinerate its way TO the heart, that would leave a hole like Mike said (the flesh in the path of the bolt en-route to the heart would be reduced to ash. There may or may not be explosive effects with turning the water to superheated steam too, depending on the speed and manner of delivery of the energy.)

[Swindle1984]

We're talking about a show where Garibaldi took six revolver cartridges, dropped them all down a steam pipe, and the steam pipe obligingly fired all six cartridges, in sequence, and magically made the casings disappear so the next bullet in line could fire.

And that's not even taking into account that he had no real way of aiming it even if you didn't include the lack of rifling or proper "bore" diameter, causing the bullet to not spin to stabilize its flight and to bounce around the pipe as it went down-range.

I don't think weapons physics was ever really thought out by the B5 crew.





As for gravity not affecting the (in the words of John Crichton) little yellow bolts of light coming out of PPG's, if the projectiles are supposedly made of superheated helium, wouldn't they actually RISE rather than gradually drop like bullets? Heat, expansion, and simply being helium would all, so far as my limited understanding of physics goes, cause the projectile to disperse and rise almost immediately after being fired, burning the user's eyebrows off and setting fire to the ceiling.

[Darth Wong]

As for gravity not affecting the (in the words of John Crichton) little yellow bolts of light coming out of PPG's, if the projectiles are supposedly made of superheated helium, wouldn't they actually RISE rather than gradually drop like bullets?

They must be highly compressed by some mechanism in order to exhibit such destructive effects upon impact.

Heat, expansion, and simply being helium would all, so far as my limited understanding of physics goes, cause the projectile to disperse and rise almost immediately after being fired, burning the user's eyebrows off and setting fire to the ceiling.

The realistic outcome would be a short jet, like a powerful blowtorch. That's what a plasma torch looks like, after all. The gases outside the "flame" would heat the air and dissipate.

[Swindle1984]

As for gravity not affecting the (in the words of John Crichton) little yellow bolts of light coming out of PPG's, if the projectiles are supposedly made of superheated helium, wouldn't they actually RISE rather than gradually drop like bullets?

They must be highly compressed by some mechanism in order to exhibit such destructive effects upon impact.

Right, I assumed as much.

Heat, expansion, and simply being helium would all, so far as my limited understanding of physics goes, cause the projectile to disperse and rise almost immediately after being fired, burning the user's eyebrows off and setting fire to the ceiling.

The realistic outcome would be a short jet, like a powerful blowtorch. That's what a plasma torch looks like, after all. The gases outside the "flame" would heat the air and dissipate.

Since they fire bolts or bursts rather than a continuous stream, I think my analogy of a brief, instantaneous ball of fire is better, though you're probably right about it not being any more dangerous to the user than a plasma torch.

[Darth Wong]

Since they fire bolts or bursts rather than a continuous stream, I think my analogy of a brief, instantaneous ball of fire is better, though you're probably right about it not being any more dangerous to the user than a plasma torch.

It should look like a plasma torch which was briefly switched on. So you'd see what appears to be a blindingly brilliant jet of flame which switches on and off in a split-second.