[MidnightSun]

Hi

Just reading some stats earlier and found myself wondering what dictates the Ranges for guns? I can understand an Autocannon/Boltgun shell losing velocity so it's no longer effective, but what about Lascannons/Lasguns? Do they just lose power or do they stop abruptly?

Just wondering what other people think.

Midnight

 

[Daniel Harper]

I'd say they'd lose power over time, think that would make the most sense. Other than weapons such as that I'd think others would be straight forward?

 

[GrizBe]

Lasers disperse and become less focused the further the distance they travel, so pretty much, after so far, they'd not have the power to do damage anymore.

 

[Azezel]

Grizbe is right. Laser beams diffract (spread out, to you).

A handy little equation for calculation the diffraction of a laser beam at a given range is:
RT = 0.61*D*L/RL
where:
RT = the radius of the beam at the specified range in meters
D = The range from the focusing lens or mirror in meters.
L = The wavelength of the laser light in meters
RL = The radius of the focusing lens or mirror in meters.

Depending on the raw power available, the wavelength of your laser and the size of your lens there is a very finite upper limit to the effective range of a laser weapon.

However - instinct tells me that the range listed in the book for a given weapon is simply 'effective range' - which is another animal entirely and takes into account things like accuracy and projectile speed.

Lasers have constant speed (subject to medium, of course), bullets start very fast and slow constantly over time. Bolts start slower, then accelerate, then slow again.

 

[Holmstrom]

Effective range would be a safe conclusion to assume in the matter. Weapons of our time can kill well over a kilometer in the proper hands, but in a hectic battle situation that is of course dramatically reduced. (Example: A horde of flesh hungry xenoforms are charging to tear your face off).

And, obviously, there is the game-balance factor.

 

[yanlou]

not all weapons can kill someone over kilometre away, even in the proper hands, an SA80 for example has an effective range of 400m after that it will only travel for a few 100m more so well below what you were saying, but i will agree that on tabletop the ranges represent effective range, i mean i can see why a bolter is 24 inch ange and an autocannon is 48 inch range, due larger calibre and volocity and as for laser weapons i suspect that would eventually disperse but as pointed out depending on the different specs this would determine effective range

 

[GrizBe]

Thanks for the math stuff there Azezel.

But yeah.. its probably best to think of the ranges as 'effective ranges' due to decrease in projectile velocity, dispertion etc.

 

[King Gary]

Random fact that seems incredibly counter-intuitive, a bullet shot from a perfectly level gun, across a perfectly flat piece of ground will hit the floor at exactly the same time as a bullet dropped straight down from the same height as the barrel of the gun.

 

[darklove]

Thank you QI! I love that show

 

[Azezel]

Random fact that seems incredibly counter-intuitive, a bullet shot from a perfectly level gun, across a perfectly flat piece of ground will hit the floor at exactly the same time as a bullet dropped straight down from the same height as the barrel of the gun.

Can I get a 'duh'?

 

[King Gary]

Can I get a 'duh'?

it's not intuitive

 

[darklove]

Ultimately, gravity is a constant force acting on the bullet. Just because a bullet has been fired from a gun does not mean this force is any less, and so it will hit the ground in exactly the same time, just a lot further away

If you could shoot the bullet fast enough, and keep it moving at that speed, then it would never hit the ground because the natural curve of the earth would leave it in perpetual fall (orbit). If you shoot the bullet even faster then it won't hit the ground and just shoot straight out into space, and will then have broken free of the force of gravity (eventually).

 

[MidnightSun]

Thanks for the replies, I was just wondering. Here's some brain food: what limits the range of a Kai Gun? And what limits the range of daemonic weapons (Warpfire, Daemonic Gaze)? And I haven't even got started on Lightning Arc for the Nightbringer :biggrin:

Midnight

 

[Baron Spikey]

Maybe the instability inherent in any daemonic presence weakens them to such a degree when too far from their host that they simply dissipate.

 

[GrizBe]

Well lightning arc would probably follow the same rules as real world lightning, in that thre has to be a discharge path for it to follow, and it will usually discharge at the closest point possible.

Deamonic weapons... pretty much the instability of having to use energy to remain manifest covers that I'd guess.

 

[MidnightSun]

But the C'tan themselves do not follow the rules of the real world (Immune to Natural Law), so surely this would affect their weapons? I'm too confused...

Midnight

 

[Lucio]

Random fact that seems incredibly counter-intuitive, a bullet shot from a perfectly level gun, across a perfectly flat piece of ground will hit the floor at exactly the same time as a bullet dropped straight down from the same height as the barrel of the gun.

It wouldn't, the velocity of the first bullet warps space time so it will actually hit the ground at a different time, just not enough to measure.

Why do snipers only have 36'' range? The modern Barret has an effective range of 2 km and these are suppose to be better than that so, other than balance, what gives?

 

[MidnightSun]

Dunno, and I also don't understand Hunter-Killers. Surely if the Imperium has the tech for lock-on Krak missiles, they can have lock on Storm Eagle Missiles (Or whatever the manticore fires), or even have normal missile launchers with lock on? And just because it has a target lock, doesn't mean it's unlimited range. From here in the UK, if I fired a guided missile at something in China or Australia it probably wouldn't hit. Not if it was that small.

Snipers should definitely be longer range, as should pistols and Meltas (only by about six inches though)

Midnight

 

[darklove]

It wouldn't, the velocity of the first bullet warps space time so it will actually hit the ground at a different time, just not enough to measure.

Why do snipers only have 36'' range? The modern Barret has an effective range of 2 km and these are suppose to be better than that so, other than balance, what gives?

Modern snipers tend to work on set-pieces or covert situation where the targets are often static. That is very different from the chaos of skirmish warfare that 40k is based on. Lots of smoke and targets moving at high speed and lots of other distractions like really big and scary monsters charging you - I don't think there is much comparison with real world war.

 

[GrizBe]

Meltas are short range as they pretty much fire a stream of plasma... extreme hot and energetic gas. To contain plasma you need a high powered electromagnetic feild, so to have a beam of it at any range you'd need something to contain it in a colesant stream. Hence, Meltas are short range as it would take too much power to contain the stream in an effective beam for long enough.