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 DarknessEternal wrote:
Lasguns don't shoot lasers. They're liker blasters in Star Wars.

They "fire" some manner of heated blobish shot.

For more trivia, there are no moving parts in a lasgun, even the trigger is a touch pad.

I'm genuinely curious where you've read this, as it seems to be very different to the other replies?
I don't know if everyone creating art for 40K is similarly aware.

 DarknessEternal wrote:
Lasguns don't shoot lasers. They're liker blasters in Star Wars.

They "fire" some manner of heated blobish shot.

For more trivia, there are no moving parts in a lasgun, even the trigger is a touch pad.

As per usual, GW writers demonstrated their grand foresight for futurist laser technology:

Las weapons fire packets of explosive laser energy - the larger the gun, the more powerful the shot.
(Warhammer 40,000 Rulebook. "Appendix: Ranged Weapons of the 41st Millennium: Las Weapons". 7th Edition. Digital)

I have no idea how the laser light itself came to be explosive, but it's certainly not on the level of plasma. So it obeys all rules regarding laser techs: that is, they are light. Radiation rays are either invisible to human eyes, or visible due to being within a visible light spectrum -- not bolts.

On the other hand, GW materials, as per usual, are not quite so consistent. Many artworks in the Militarum Tempestus Codex shows the hotshot lasgun firing a continuous stream of visible light:


Others, found on both Codex: Astra Militarum, and Codex: Militarum Tempestus, shows the lasgun fires no visible projectile, but does show a sort of muzzle flare, though their certainly would not be muzzle flares as we know it, if the guns fire laser light:

Not sure what that is, but it could be the flare from a low-power lasgun shot. As in the bottom right of the image are two traitor guards/cultists/renegades, one wearing gasmask, another, dying.

Edit: looking at the image on the MT codex, maybe it does show a string of light instead of flare, as the whole image is cut off where the flare would converge into a string.

The current codex has several consecutive pages of people firing lasguns, all of which are illustrated differently...
Of particular note is the painting on page 12, which has burning streaks of air visible. It's then followed on page 14 by a picture of what appeared to be guardsmen using lens-flare guns to dazzle people. On page 39 someone else entirely clearly subscribed to the long-beam of light idea.

At a guess, folks went with what looked good at the time. Some even have embers or flecks falling from the muzzle which makes me wonder what they thought was happening.

Modern window glass absorbs or reflects about 30-50% of radiation passing through it. It is also quite susceptible to thermal shock caused by differential heating. A narrow diameter laser beam of sufficient power to cause 50-100 degC temp rise is likely to be enough to shatter a windows pane. Whether it stays in place or not after shatterring will depend on the type of glass, I. E. Toughened, laminated or simple float glass.

I always figured melta guns fired out a bit of molten metal or...something at the enemy in order to eat holes through armor.

So a lava-gun basically.

 DoomShakaLaka wrote:
I always figured melta guns fired out a bit of molten metal or...something at the enemy in order to eat holes through armor.

So a lava-gun basically.

No, meltaguns fire beams of fusion or superheated air in excess of tens of millions of degrees that outright vaporizes most things it hits. Like Huron's spleen.

It wasn't actually the melta that nearly killed Huron, it was his exploding archeotech lightning claw.

Ron Who?

Irritatingly, the best animated depiction of a melta weapon I've seen was in Space Marine, which has them work like a kind of shotgun with no visible shot, and there they got the sound 'wrong' (by white dwarf fluff...)

Dawn of War, on the other hand, has them as some kind of long-range flare gun that achieves very little for a lot of glowing blue beams for some reason.

 Furyou Miko wrote:
Ron Who?

Irritatingly, the best animated depiction of a melta weapon I've seen was in Space Marine, which has them work like a kind of shotgun with no visible shot, and there they got the sound 'wrong' (by white dwarf fluff...)

Dawn of War, on the other hand, has them as some kind of long-range flare gun that achieves very little for a lot of glowing blue beams for some reason.

No, Dawn of War is accurate. Meltaguns are beam weapons, not shotguns with a cone of fire the size of a man.

The sun seems to warm up my windows even though the light passes through. I assume a laser would melt a hole through the same window or shatter it. The distance between energy states/levels/orwhathaveyou between the electrons of tranparent materials is too big for a photon at the normal light spectrum to have any effect. Iwth other meterial the photon is absorbed and excites an electron to it's next energy state. Glass allows normal spectrum to pass through as it's not enough to push electrons to their next state but the same window allowing visible light though doesn't allow the Ultraviolet radiation from the sun to get through as it's enough energy to get absorbed by the glass move electrons. You can't get tanned behind a window. The energy of a close up lasgun seems to be higher then the effects of our star's rays hitting us from far away.

 Wyzilla wrote:

 Furyou Miko wrote:
Ron Who?

Irritatingly, the best animated depiction of a melta weapon I've seen was in Space Marine, which has them work like a kind of shotgun with no visible shot, and there they got the sound 'wrong' (by white dwarf fluff...)

Dawn of War, on the other hand, has them as some kind of long-range flare gun that achieves very little for a lot of glowing blue beams for some reason.

No, Dawn of War is accurate. Meltaguns are beam weapons, not shotguns with a cone of fire the size of a man.

I was only talking about the animation - the melta beam is invisible.

Not necessarily, in a controlled environment maybe, but in the dust that is kicked up in a battlefield will probably be heated enough to glow, or at least combust very brightly.

How do lasguns work?

Well, lasguns give the common soldier of the Imperium the delusion that they exist for some purpose other than providing something for the enemy to shoot that isn't a tank.

I'm sure it is theoretically possible that lasguns do something else... but I don't think that's their point.

 EmpNortonII wrote:
How do lasguns work?

Well, lasguns give the common soldier of the Imperium the delusion that they exist for some purpose other than providing something for the enemy to shoot that isn't a tank.

I'm sure it is theoretically possible that lasguns do something else... but I don't think that's their point.

And that's why I use autoguns.

Then you know you're genuinely useless in the 41st millennium.

Oh I don't know.. Quite often I'm allowed to get to very nasty places with my troopers purely because the opposition believe they're useless, and are too busy focusing on the tanks...

Then they either feth up spectacularly or demonstrate the infinite monkeys, infinite typewriter effect.

 Buttery Commissar wrote:
Oh I don't know.. Quite often I'm allowed to get to very nasty places with my troopers purely because the opposition believe they're useless, and are too busy focusing on the tanks...

Then they either feth up spectacularly or demonstrate the infinite monkeys, infinite typewriter effect.

Once had a single veteran beat up a terminator in CC. My opponent couldn't believe it XD

Assuming lasguns are lasers (because otherwise the whole conversation goes to an unhelpful place), window glass isn't perfectly transparent (look at the edge of a pane; it's green because some light is absorbed). Without running the numbers (look for the thread on Stardestroyer.net if you really want to), the lasbolt is probably energetic enough that the glass will absorb enough energy to melt, and quite possibly explosively vapourise, causing the glass to shatter. Same goes for mirrors (although some specialised mirrors or a reflective energy shield would allow for reflection of the shot).

As for the explosive vapourisation of bodily fluids, I would think that the vapour would be constrained by the surrounding tissue and fluid - it's easier for it to escape into the air. There'd be some heat rtransfer, I would think, resulting in burns to surrounding tissue, and I would think that any vapour forced into adjoining blood vessels will be cooled back to liquid pretty quickly.

As an aside, Space Marine shoulder-fired lascannon have recoil compensators. Making some assumptions, I worked out what sort of power output that would require, but I've long lost the calculation. I don't think it was correct in any case.

Regarding heroic guardsmen, I've had a Company officer beat up a Blood Angels captain in melee, and a trooper gun down a Grey Knight terminator. In the same battle.

Their the standard issue flashlight for people too smart to correct the man with a bolt pistol, also known as commissar.

They work by clicking the "trigger" and send forth a 1 second burst beam of light to illuminate areas. As such. It would just send light through the window, however hundreds of lasguns tied together and fired at a single point has been known to ignite a Commissars cigar.

 Dylanj94 wrote:
Their the standard issue flashlight for people too smart to correct the man with a bolt pistol, also known as commissar.

They work by clicking the "trigger" and send forth a 1 second burst beam of light to illuminate areas. As such. It would just send light through the window, however hundreds of lasguns tied together and fired at a single point has been known to ignite a Commissars cigar.

And several thousand are known to occasionally make a tau firewarrior slightly warm.

Like Star Trek's Heisenberg Compensators, the answer to the question in the thread title is "Very well, thank you."

 AndrewGPaul wrote:
As an aside, Space Marine shoulder-fired lascannon have recoil compensators. Making some assumptions, I worked out what sort of power output that would require, but I've long lost the calculation. I don't think it was correct in any case.

I did a physics.
Basically, the momentum given by a photon is equal to planck's constant over the wavelength, and the energy given by a photon is equal to planck's constant times the speed of light over the wavelength.

This boils down to give Energy = Momentum x Speed of Light unless I've done something horribly wrong.

Now, we could use the momentum to work out the force if we knew how long a lascannon fired for, but I'm not sure this is necessary. Rather, we can work out that compensators would only be needed if the momentum transferred was significant enough to actually move the space marine. Now the blast only lasts a fraction of a second and needs to be very accurate, so let's say enough force to make the marine move 0.01 meter per second (this is a very low estimate, but it would be enough to throw their aim wild at the very least). An average person weighs around 75 kg. A space marine is not an average person, and their armour and gun will amost certainly be very heavy so let's say 200 kg should do the trick (again, a low estimate but oh well).

Plugging 2 kg m/s into the equation, we get out the other side... we get a total of 6 *10^8 Joules, which comes to approximately one thousandth of the power a nuclear reactor puts out. Given that the estimates have been very low, and future technology should allow for a heck of a lot of power to be stored, this is arguably a realistic number. However if you're putting a hole in a tank then it seems to me that it's a very ungainly way of transferring that much power when you could chuck explosives at it instead.

 AndrewGPaul wrote:
Like Star Trek's Heisenberg Compensators, the answer to the question in the thread title is "Very well, thank you."

To tell the truth, the topic title is a play on "fething magnets, how do they work?" but I didn't want to cuss on something that ends up on the main forum page every time it's replied to.

I'm also gonna have a furtle through the background forum and link up a few more Lasgun topics in the OP because I've seen a few really good questions in the past.

 Wyzilla wrote:

 DarknessEternal wrote:
Lasguns don't shoot lasers. They're liker blasters in Star Wars.
They "fire" some manner of heated blobish shot.
For more trivia, there are no moving parts in a lasgun, even the trigger is a touch pad.

No, lasguns have always been explicitly true lasers. Blasters meanwhile are also just plasma weapons.

Sadly pure lasers are absolutely terrible weapons for small arms.
The amount of heat required to actually injure an enemy that is composed mostly of water is immense.
Assuming you could wield that much power compactly, the effectiveness drops considerably when you introduce battlefield conditions.
Assuming you have even more power to get through all the dirt, grime, smoke of battlefield conditions, reflective/disruptive armor against lasers would be very effective and low cost.

laser weapons have some real advantages, particularly at extremely long range, when tracking extremely fast/manuverable targets, or when you happen to have a few gigawatts of power laying around.


Automatically Appended Next Post:

 AndrewGPaul wrote:
Assuming lasguns are lasers (because otherwise the whole conversation goes to an unhelpful place), window glass isn't perfectly transparent (look at the edge of a pane; it's green because some light is absorbed). Without running the numbers (look for the thread on Stardestroyer.net if you really want to), the lasbolt is probably energetic enough that the glass will absorb enough energy to melt, and quite possibly explosively vapourise, causing the glass to shatter. Same goes for mirrors (although some specialised mirrors or a reflective energy shield would allow for reflection of the shot).

Depends on the glass/mirror. Some are 90% transparant/reflective, others are 99%. Similarly some glass is vulnerable to thermal shock, some types are not.

 AndrewGPaul wrote:

As for the explosive vapourisation of bodily fluids, I would think that the vapour would be constrained by the surrounding tissue and fluid - it's easier for it to escape into the air. There'd be some heat rtransfer, I would think, resulting in burns to surrounding tissue, and I would think that any vapour forced into adjoining blood vessels will be cooled back to liquid pretty quickly.

Getting to vaporation of any apprciable amount of body fluid is a lot more energy than is likely required to harm someone. Boiling water requires a ton of energy, energy that would probably not be there. At the point you are vaporizing a leg of a human, you have a beam that could probably cut through tank armor or certainly down aircraft with ease.

Running numbers im beggining to think lasguns should be strength 1, AP2, gets hot weapons.

Actually it wouldn't take much energy. Surgical lasers are barely over 100w and can cut through flesh with ease. Seeing as a lasgun can instantaniously microwave parts of a human body and is from the far future we can assume that it can hold more energy than modern batteries.

Smoke and dust can prevent weak laser pointers but that isn't anyway near enough to prevent the heavier duty lasers, let alone a lasgun on its lowest setting with its battery almost drained. Unless it starts raining actual diamonds, there's not going to be any real battlefield conditions that would hamper it.

As for reflective armor, most mirrors only reflect visible light. Heat and radiation won't be reflected so easily and not only that but somthing as small as a speck of dust could heat up and cause the entire thing to melt instantly. It may be possible but there is no cult that would be capable of creating standard armor consisting of graphite/diamond level materials at a perfect consistent quality on a mass production scale. Even if this armor did work, a large amount of the heat and radiation is still getting through, it would be like pouring boiling water down your shirt straight from the kettle and then setting your clothes on fire.

Also I don't know what sort of tanks you're thinking of but a human body can't take as much heat as a tank or aircraft can.

Depends. A laser is going to do damage by transferring heat energy, and one random thing to note is that water (i.e. the human body) takes more energy to heat per unit volume than most solid metals.

Which supports the idea that a laser is a rubbish antipersonnel weapon but a good antitank weapon.

Good point, I stand corrected, although I'd argue that a tank would be better able to carry materials that reflect a lasgun than anything a soldier could wear.

Apparently there's a theory by some German scientist that it only takes 1 Terahertz of radiation to flash boil water to 600°c in a trillionth of a second. It's unproven but suppose a lasgun could get to a fraction of that enegy, it would be more than capable of being a lethal weapon.

locarno24 wrote:
Depends. A laser is going to do damage by transferring heat energy, and one random thing to note is that water (i.e. the human body) takes more energy to heat per unit volume than most solid metals.

Which supports the idea that a laser is a rubbish antipersonnel weapon but a good antitank weapon.

Unit mass, not unit volue. Although water is dense, but not super dense so it does also work out per unit volume.

Yeah it's all in the specific heat.
Water has a super high 4.18 Joules per gram.
Iron is 10 times lower at .45 Joules per gram.
Most plastics are around 1 Joules per gram.
Tungsten Carbide is .17 Joules per gram.

So heating up water take an order of magnitude more energy than heating most other materials.

A lasweapon outputs 18 megathules of energy.

What's a megathule? No one freakin' knows.

We are provided in numerous sources evidence that lasweapons have the ability to deliver significant tissue damage to human/human-equivalent targets, in some cases severing limbs or blowing meaty chunks out of people.

We're also told in numerous places that lasguns deliver "thermo-kinetic" energy, so part-heat, part-punch... the latter probably compensating for energy bleed-off, thermal loss, etc.

A long winded and rambling discussion of laser weapon power requirements and realism froma few years ago

http://www.dakkadakka.com/dakkaforum/posts/list/0/539592.page