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So I am thinking about modifying my predator to have two extra lascannons somehow attached to its turret as opposed to the sponsons and I am curious, do they have any recoil and how heavy are they?

Lascannons use lasers (a form of light) so recoil would be nonexistent. However, the weight and volume of Lascannons power cells are gargantuan.

I read recently they are finding that larger Lasers may have recoils. Its not on the same scale as a conventional Fire Arm, but it does happen. Laser recoil would start to matter on the galactic ship scale, because even small recoils scaled up to a lance size would be significant in a friction-less environment like space. On a terrestrial vehicle that deals with friction and gravity, it probably would be inconsequential though.

As long as it looked well done and you didn't try to claim that all the lascannons were now turreted for rules purposes, it would be fine.

 GKTiberius wrote:
I read recently they are finding that larger Lasers may have recoils. Its not on the same scale as a conventional Fire Arm, but it does happen. Laser recoil would start to matter on the galactic ship scale, because even small recoils scaled up to a lance size would be significant in a friction-less environment like space. On a terrestrial vehicle that deals with friction and gravity, it probably would be inconsequential though.

The several km long massive spacecraft still have horrendous inertia to overcome first. Sure, eventually, all those nudges might amount to something, but by the time the battle is over (space battles in the fluff do not last that long - things tend to die when you let their air out).

photons have momentum, so they will cause recoil. It's the principle behind the photon rocket and the solar sail.

 chromedog wrote:

 GKTiberius wrote:
I read recently they are finding that larger Lasers may have recoils. Its not on the same scale as a conventional Fire Arm, but it does happen. Laser recoil would start to matter on the galactic ship scale, because even small recoils scaled up to a lance size would be significant in a friction-less environment like space. On a terrestrial vehicle that deals with friction and gravity, it probably would be inconsequential though.

The several km long massive spacecraft still have horrendous inertia to overcome first. Sure, eventually, all those nudges might amount to something, but by the time the battle is over (space battles in the fluff do not last that long - things tend to die when you let their air out).

But consider a shot perpendicular to the ship. The ship may bee moving forward but it doesn't have the friction or traction from wheels to stabilizes perpendicular forces. Even water around navel vessels provides stability for large naval guns. This dampening force does not exist in space as there is no matter influencing the sides of the ship in this way.

Manoeuvring thrusters. they'll be all over the ship, and will easily be able to cancel out the miniscule reaction force from firing laser weapons. After all, they already need to handle the recoil from projectile weapons, which will be much greater.

 GKTiberius wrote:

 chromedog wrote:

 GKTiberius wrote:
I read recently they are finding that larger Lasers may have recoils. Its not on the same scale as a conventional Fire Arm, but it does happen. Laser recoil would start to matter on the galactic ship scale, because even small recoils scaled up to a lance size would be significant in a friction-less environment like space. On a terrestrial vehicle that deals with friction and gravity, it probably would be inconsequential though.

The several km long massive spacecraft still have horrendous inertia to overcome first. Sure, eventually, all those nudges might amount to something, but by the time the battle is over (space battles in the fluff do not last that long - things tend to die when you let their air out).

But consider a shot perpendicular to the ship. The ship may bee moving forward but it doesn't have the friction or traction from wheels to stabilizes perpendicular forces. Even water around navel vessels provides stability for large naval guns. This dampening force does not exist in space as there is no matter influencing the sides of the ship in this way.

It still needs to overcome the inertia of the several billion kilogram ship. Inertia isn't dependent on moving forward; it is, as Bill Nye tells us, a property of matter. You still need to have a huge force in order to push an object like that in space. You can't, for example, just hop of the airlock, push off with your feet, and send the ship off course.

 KharnsRightHand wrote:

 GKTiberius wrote:

 chromedog wrote:

 GKTiberius wrote:
I read recently they are finding that larger Lasers may have recoils. Its not on the same scale as a conventional Fire Arm, but it does happen. Laser recoil would start to matter on the galactic ship scale, because even small recoils scaled up to a lance size would be significant in a friction-less environment like space. On a terrestrial vehicle that deals with friction and gravity, it probably would be inconsequential though.

The several km long massive spacecraft still have horrendous inertia to overcome first. Sure, eventually, all those nudges might amount to something, but by the time the battle is over (space battles in the fluff do not last that long - things tend to die when you let their air out).

But consider a shot perpendicular to the ship. The ship may bee moving forward but it doesn't have the friction or traction from wheels to stabilizes perpendicular forces. Even water around navel vessels provides stability for large naval guns. This dampening force does not exist in space as there is no matter influencing the sides of the ship in this way.

It still needs to overcome the inertia of the several billion kilogram ship. Inertia isn't dependent on moving forward; it is, as Bill Nye tells us, a property of matter. You still need to have a huge force in order to push an object like that in space. You can't, for example, just hop of the airlock, push off with your feet, and send the ship off course.

I'm not saying that a single laser pointer is going to rock a massive battle ship, but what I am saying is if i'm going to be firing a laser lance beam that is several meters across and contains energy on the multi Tera-joule level, it could potentially have some effect, especially if I'm firing multiple dozens at once. Also I'm not a physicist so I could be wrong, but I understand inertia to be the tendency for an object in motion to stay in motion , or at rest unless acted upon by an outside force. So a large energy burst from a laser could potentially exert enough force on the ship to matter, especially if the laser is being fired perpendicular to the movement of the ship, and the ship is say the size of a cruiser or corvette. I'm not saying it will wreck the ship, but something may be needed to compensate for this.

I disagree. The weight and reaction of even a giant laser wouldn't be enough to shift a large ship in space very much at all. The ships weight is almost guaranteed to be large enough that the emission of photons would only cause a negligible effect on its movement, which could easily be countered by a very weak thruster or ignored.




Automatically Appended Next Post:
If the gun did more than just emit photons, we may have some recoil. If the generation of such a photon stream required some other force to be exerted by moving parts in the ship or something else, there would be recoil.

AncientSkarbrand wrote:
I disagree. The weight and reaction of even a giant laser wouldn't be enough to shift a large ship in space very much at all. The ships weight is almost guaranteed to be large enough that the emission of photons would only cause a negligible effect on its movement, which could easily be countered by a very weak thruster or ignored.

Exactly.

Or turning slightly towards the side that's firing and performing a very short burn of the main drive.

Both of your examples are forms of compensation for the minuscule recoil of a laser weapon. I'm not saying its going rock the ship or displace the gun through violent force. In fact, I doubt the crew of the ship would even notice the recoil. But the recoil, even on a minuscule level could affect the trajectory and telemetry of the ship moving through space. Something might be needed to compensate for that. A small thruster or a slight course correction by fractions of a degree. This could even be automatically done through the ship's computer. Again there is a difference between small and nonexistent, and a massive laser could potentially have an effect that would need to be compensated for.

But that sort of extremely minor lateral force would not need to be compensated for in combat.

Compared to missile launches or impacts it's negligible, lasers fired from the other side's battery would cancel the effect and, most importantly, a very minor lateral deviation like that would only become significant after travelling a long distance.

During combat it could safely be completely ignored.

I wasnt even fully sure they shoot light, I heard a few times that las weapons in 40k shoot some sort of a fancy laserish projectile as opposed to an actual laser

 Daemonhammer wrote:
I wasnt even fully sure they shoot light, I heard a few times that las weapons in 40k shoot some sort of a fancy laserish projectile as opposed to an actual laser

The only practical way to "fire" pure energy without some other conductor is to use photons, IE: light. Which is what a laser does. Now the term Laser technically refers to the device which emits a beam of coherent light in a particular way, not the beam itself. So you could have devices which create an identical effect with a different method.

So a lance beam might be identical to a laser beam, but its not a laser because the device isn't a laser.