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Underwater weapons


ARS

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So far, I've seen several kinds of underwater weapons, such as torpedoes, depth charges, mines, harpoons, etc. Being underwater, ballistic weapons have a limitation of water resistance that severely limits their effectiveness. What I want to ask is:

-does railguns make a good weapon underwater? Especially with it's extremely high projectile velocity? (Assume it's size and caliber is around current day destroyer main gun)

-how about lasers? Especially high intensity laser (assume it's size is same like railguns mentioned above)

What kind of advantage (if any) and disadvantage of those two weapons above if used underwater? Or if any of you have an idea for a theoretical underwater weapons, let me know about it

Anyway, thanks for your answer :)

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13 minutes ago, ARS said:

does railguns make a good weapon underwater? Especially with it's extremely high projectile velocity? (Assume it's size and caliber is around current day destroyer main gun)

-how about lasers? Especially high intensity laser (assume it's size is same like railguns mentioned above)

No, and no.

With a railgun, drag will slow the projectile very, very quickly.

With lasers, the ocean is too dense (and the wrong color for many lasers).

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54 minutes ago, ARS said:

does railguns make a good weapon underwater? Especially with it's extremely high projectile velocity? (Assume it's size and caliber is around current day destroyer main gun)

No.

You should, however, consider bolters and other rocketguns. There is already a company that’s busy resurrecting the Gyrojet for that purpose.

54 minutes ago, ARS said:

-how about lasers? Especially high intensity laser (assume it's size is same like railguns mentioned above)

If it’s green, maybe. But then you have the problems of lasers in general.

54 minutes ago, ARS said:

Or if any of you have an idea for a theoretical underwater weapons

You failed to mention something developed by a guy sharing my surname.

5.45mm_ADS_rifle_-_InnovationDay2013part

And given the anime avatar, I’m mildly angered you don’t know about Soviet/Russian underwater assault rifles.

BLAPS.jpg

Edited by DDE
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Underwater its hard to beat the torpedo for large weapons.
For small arms I think using the gyrojet concept would be perfect, because of the high drag in water you would want to use constant trust rather than getting out of an barrel at high speed.
Yes this will work a bit like an torpedo, this could also be scaled up too an mini torpedo as an smart weapon, think an rpg. You can shape the nose to get an supercavitating effect

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1 minute ago, DDE said:

You can always get better response time by having your weapon leap of out the water, fire a rocket motor, and then toss a torpedo towards your target.

You mean something like VLS fired from underwater out of water and then drop the torpedo from the air?

28 minutes ago, magnemoe said:

For small arms I think using the gyrojet concept would be perfect, because of the high drag in water you would want to use constant trust rather than getting out of an barrel at high speed.

I'm still a bit confused about the prospect of underwater gyrojet. In real life, the project is designated as a failure of a weapon since when fired (on the air) it starts slow and then gaining speed. The problem is, from what I know, it deals almost no damage from point blank range since the bullet starts slow, yet the rocket motor makes it innacurate from long range since it tends to veer off course. What the difference it makes underwater? Which generates even more resistance than air?

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38 minutes ago, ARS said:

I'm still a bit confused about the prospect of underwater gyrojet. In real life, the project is designated as a failure of a weapon since when fired (on the air) it starts slow and then gaining speed. The problem is, from what I know, it deals almost no damage from point blank range since the bullet starts slow, yet the rocket motor makes it innacurate from long range since it tends to veer off course. What the difference it makes underwater? Which generates even more resistance than air?

Idea don't make much sense in air but more in water simply because water limit top speed a lot.
You go slower so you want longer bullets, think small arrows, this allows more fuel. have it fast burning at start to get up to speed fast then sustain. 
Make me thinking if you could use lithium as part of fuel as it react with water for extra trust?
 

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2 hours ago, ARS said:

You mean something like VLS fired from underwater out of water and then drop the torpedo from the air?

This totally exists. As do torpedo-tube launched weapons of similar capability. It should be noted that this is very revealing of the submarine's location.

2 hours ago, ARS said:

I'm still a bit confused about the prospect of underwater gyrojet. In real life, the project is designated as a failure of a weapon since when fired (on the air) it starts slow and then gaining speed. The problem is, from what I know, it deals almost no damage from point blank range since the bullet starts slow, yet the rocket motor makes it innacurate from long range since it tends to veer off course. What the difference it makes underwater? Which generates even more resistance than air?

The gyrojet actually had a lot of potential. Its downfall was almost completely due to a defect in the manufacturing of the ammunition which meant the exhaust ports in the bullets were misaligned and/or blocked/restricted. This meant that the rotational stability it was supposed to have (from slightly offset exhaust) was unreliable at best, and acceleration unreliable.

Another problem was that its strange way of firing the round - the hammer struck the front of the bullet, striking it against a fixed firing pin at the rear, the bullet the re-cocked the hammer with its forward motion. Unfortunately, due to the defective ammo, it was common for the round to not be able to pass the hammer, and waste its propellant in the breech.

However, it saw some action in Vietnam and was popular due to its stopping power at range, light barrel, little recoil, and unusual sound signiture which did not solely originate from the shooters location, offering a measure of concealment.

 

Edited by p1t1o
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8 hours ago, ARS said:

So far, I've seen several kinds of underwater weapons, such as torpedoes, depth charges, mines, harpoons, etc. Being underwater, ballistic weapons have a limitation of water resistance that severely limits their effectiveness. What I want to ask is:

-does railguns make a good weapon underwater? Especially with it's extremely high projectile velocity? (Assume it's size and caliber is around current day destroyer main gun)

-how about lasers? Especially high intensity laser (assume it's size is same like railguns mentioned above)

What kind of advantage (if any) and disadvantage of those two weapons above if used underwater? Or if any of you have an idea for a theoretical underwater weapons, let me know about it

Anyway, thanks for your answer :)

Water has a distance related adsorption of longer wavelength light that makes everything look blue underwater. The problem is that light scattering is the inverse forth power of the wavelength which means the blue spectrum easily scatter. This ultimately limits the travel of light in sea water to about 200 feet.

A steam or electricity driven torpedo is an object that maintains a constant speed to its target but whose destructive power is not related to its speed but its payload. Consequently it controls the energy lost though drag created by projectiles in which the projectile is the payload. In WWI and WWII era torpedos had to make a single turn (based on a setting made a launch) and then intercept a target at a given location. All of these steps proved to be problematic. Torpedo's either never turned or never stopped turning, they often (particularly in WWII) went under the target or the charges detonated before they reached their targets.

After 1970 the torpedos were guided by  a very thin control wire making it one of the most accurate long distance targeting devices underwater. Theoretically torpedos can be guided now by satellite transmission instead of wire, in this case the torpedo would be fired and a set of directives sent to satellites orbiting above the battle area, the satellite would observe the torpedo and targets progress in order to maximize intercept.

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1 hour ago, PB666 said:

Water has a distance related adsorption of longer wavelength light that makes everything look blue underwater. The problem is that light scattering is the inverse forth power of the wavelength which means the blue spectrum easily scatter. This ultimately limits the travel of light in sea water to about 200 feet.

A steam or electricity driven torpedo is an object that maintains a constant speed to its target but whose destructive power is not related to its speed but its payload. Consequently it controls the energy lost though drag created by projectiles in which the projectile is the payload. In WWI and WWII era torpedos had to make a single turn (based on a setting made a launch) and then intercept a target at a given location. All of these steps proved to be problematic. Torpedo's either never turned or never stopped turning, they often (particularly in WWII) went under the target or the charges detonated before they reached their targets.

After 1970 the torpedos were guided by  a very thin control wire making it one of the most accurate long distance targeting devices underwater. Theoretically torpedos can be guided now by satellite transmission instead of wire, in this case the torpedo would be fired and a set of directives sent to satellites orbiting above the battle area, the satellite would observe the torpedo and targets progress in order to maximize intercept.

You also has acoustic torpedoes, this dates back to ww2 and was the first smart weapon, yes they was unreliable back then.
Even the line controlled ones has an acoustic mode, you will typical activate this then you have an lock on target. You can probably also set it to search but that would be dangerous if other ships are nearby. 
 

Explosives work very well underwater as water can not be compressed, no need for stuff like shaped charges or shrapnel. 

 

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7 hours ago, ARS said:

You mean something like VLS fired from underwater out of water and then drop the torpedo from the air?

VLS is just the most recent delivery platform for... well, English doesn't have a proper word that encompasses all of ракетоторпеды. Funnily enough, the same 533 mm payloads are standardized across older surface ships and submarines, so, say, if you liquided off the Indian navy, they'd either have to close into range of their RBUs, which are a Katyusha-Hedgehog hybrid, or:

  1. Load their antisubmarine missiles into old-school (i.e. WWII-style) five-tube torpedo launchers
  2. Fire the missiles overboard
  3. Missiles go underwater
  4. Rockets fire
  5. Missiles exit water
  6. Missiles fly through air
  7. Missiles release their torpedo payloads
  8. Torpedoes deploy braking ballutes
  9. Torpedoes hit water
  10. Torpedoes try to lock onto the nearest apparent contact

Yeah, really. They don't seem to have any rail or VLS-launched designs, just the kind I linked to, and the old Kamov helicopters can't simultaneously carry sensors and torps. That's why Russian munition producers still sell anti-submarine variants of RBK-500 cluster munitions and the UDAV series of sonar-guided bombs.

Edited by DDE
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modern heavy weight torpedos are quite smart weapons. purely from an engineering perspective, they are closer to autonomous submarine robots than the dangerous to use dumb weapon most folks think they are. if properly set up they will way point their way to a target box (an area designated by the user as the area within which the target should be, but non-targets wont be), then try to locate the target using a combination of active and passive sonar. they can even go a further step and be set to identify the target by listening for the unique frequency combinations of that vessel. once acquired, the torpedo will work out where the target is and where its going, then plot its own intercept course aiming at the estimated centre of mass. only when its on the final leg of this course will it arm the warhead. this can be triggered a number of ways based on the torpedos position, depth, the targets magnetic signature, the acoustic changes as it passes under the target. oh yeah, torps dont hit anything. not on purpose. they explode under the keel of the ship making a massive shock wave that lifts the centre of the ship, which then falls into the huge cavitation bubble the blast made, then gets shoved upward again as the bubble collapses. this essentially breaks the ships in half like a toddler snaps a bread stick. if the weapon isnt happy with its position under the target, it will chose not to detonate and instead will try again by driving away and re-homing. if at any point the weapon leaves the target box it will shut down. if at any time it enters one of potentially many safety boxes, it will shut down. all the boxes can be made to move so a box can be drawn around a friendly passing through and made to move on the same course and speed. all this is what these things do without wire guidance. with wire guidance (assuming someone doesn't accidentally tell it bad info) they can be even more effective. also, not saying it isn't so, but satellite signals are quite hard to receive through a dozen meters of sea water with a necessarily tiny antenna...

 

thats all in a huge death tube with almost half a cubic meter of sensors and computers. in a man portable, hand fire weapon you could probably load a set of defaults that would see valid homing most of the time. there is no reason that a 30cm long, 50mm mini torpedo couldn't be made. we have gyros and accelerometers that fit in coins, and computers small enough to process their information into inertial navigators as well. we also are able to pack quite a bit of digital audio processing into a tiny package. the only limitation i can see is the size of the acoustic transducers in the sonar. the smaller they are, the higher their lowest frequency is. lower frequencies have less attenuation than higher ones, so can make a longer range detection, but higher frequencies can detect smaller objects with greater accuracy. most likely such a tiny torpedo would have a detection range of 100 meters or so, but be quite accurate inside that range. thats not to say thats the max range of the weapon, just that thats the range at which it needs to get to before it can automatically home. so if you know that your target can move at 5m/s (pretty average swimming? i dunno? swimming is something for targets to do after they get hit) then if you fire at centre of mass you have 20 seconds before the target is 100m away from your aim point. assuming your mini torp can travel at 20m/s, that gives you a firing range of 400m. call it 350m to allow for the initial acceleration. of course the faster your target, the closer you have to be so it cant get out of the detection range before the torp gets there. you can add in fail safes: like if its within 100m of its firing position and moving towards it, it shuts down.

mini torp: do-able.

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On 13.11.2017 at 10:23 PM, SinBad said:

modern heavy weight torpedos are quite smart weapons. purely from an engineering perspective, they are closer to autonomous submarine robots than the dangerous to use dumb weapon most folks think they are. if properly set up they will way point their way to a target box (an area designated by the user as the area within which the target should be, but non-targets wont be), then try to locate the target using a combination of active and passive sonar. they can even go a further step and be set to identify the target by listening for the unique frequency combinations of that vessel. once acquired, the torpedo will work out where the target is and where its going, then plot its own intercept course aiming at the estimated centre of mass. only when its on the final leg of this course will it arm the warhead. this can be triggered a number of ways based on the torpedos position, depth, the targets magnetic signature, the acoustic changes as it passes under the target. oh yeah, torps dont hit anything. not on purpose. they explode under the keel of the ship making a massive shock wave that lifts the centre of the ship, which then falls into the huge cavitation bubble the blast made, then gets shoved upward again as the bubble collapses. this essentially breaks the ships in half like a toddler snaps a bread stick. if the weapon isnt happy with its position under the target, it will chose not to detonate and instead will try again by driving away and re-homing. if at any point the weapon leaves the target box it will shut down. if at any time it enters one of potentially many safety boxes, it will shut down. all the boxes can be made to move so a box can be drawn around a friendly passing through and made to move on the same course and speed. all this is what these things do without wire guidance. with wire guidance (assuming someone doesn't accidentally tell it bad info) they can be even more effective. also, not saying it isn't so, but satellite signals are quite hard to receive through a dozen meters of sea water with a necessarily tiny antenna...

 

thats all in a huge death tube with almost half a cubic meter of sensors and computers. in a man portable, hand fire weapon you could probably load a set of defaults that would see valid homing most of the time. there is no reason that a 30cm long, 50mm mini torpedo couldn't be made. we have gyros and accelerometers that fit in coins, and computers small enough to process their information into inertial navigators as well. we also are able to pack quite a bit of digital audio processing into a tiny package. the only limitation i can see is the size of the acoustic transducers in the sonar. the smaller they are, the higher their lowest frequency is. lower frequencies have less attenuation than higher ones, so can make a longer range detection, but higher frequencies can detect smaller objects with greater accuracy. most likely such a tiny torpedo would have a detection range of 100 meters or so, but be quite accurate inside that range. thats not to say thats the max range of the weapon, just that thats the range at which it needs to get to before it can automatically home. so if you know that your target can move at 5m/s (pretty average swimming? i dunno? swimming is something for targets to do after they get hit) then if you fire at centre of mass you have 20 seconds before the target is 100m away from your aim point. assuming your mini torp can travel at 20m/s, that gives you a firing range of 400m. call it 350m to allow for the initial acceleration. of course the faster your target, the closer you have to be so it cant get out of the detection range before the torp gets there. you can add in fail safes: like if its within 100m of its firing position and moving towards it, it shuts down.

mini torp: do-able.

Make me thinking, the obvious weapon to defend against enemy torpedoes is an counter torpedo, this can be smaller, not handheld but perhaps 15x100 cm. it don't need much range, 1-2 km would be more than enough. Objective is to intercept and destroy enemy torpedoes. 

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10 hours ago, magnemoe said:

Make me thinking, the obvious weapon to defend against enemy torpedoes is an counter torpedo, this can be smaller, not handheld but perhaps 15x100 cm. it don't need much range, 1-2 km would be more than enough. Objective is to intercept and destroy enemy torpedoes. 

Paket-NK, 324 mm, 1.4 km against torpedoes, 20 km against conventional targes. If I’m reading it right, the 20 km range is for a conventional monorpopellant torp, whereas the M-15 antitorpedo is a mini-Shkval solid-fuel rocket, but with the same 50 knot top speed due to lack of a supercavitation tip.

I6ATTpLsedS0DgChHJmRRxnCC_ppN94u0TU-tFFb

Buy yours today.

That’s technically the second Soviet/Russian antitorpedo system. The RBU series of depth charge rocket launchers have been designated as anti-torpedo-capable for decades, and it’s not like people hadn’t tried to shoot incoming torpedoes (to little effect) prior to that.

RBU-12000/UDAV-1 is particularly sophisticated. The first two rockets drop four Nixie-style decoys, the next salvo plants a minefield in front of the torpedo, and only the third one aims for the kill with ordinary HEs. I’m surprised the 2038 corvettes and 11356 frigates don’t mount them.

Edited by DDE
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Then make it flat and let it bounce.

Spoiler

hqdefault.jpg


When an incompressible fluid flow meets an immovable barrier, a "water hammer" effect happens.
It causes immediate local growth of pressure up to ~ (FluidDensity * FlowVelocity * SoundSpeedInTheFluid) value.
That's why the hydraulic valves have to be closed gradually, otherwise you get a water hammer in your pipeline where the valve stops the water flow, and this can must burst your pipe.

A cumulative shell also works this way, you get a super-high local pressure when the metal funnel gets collapsed under the external explosion pressure, and its liquified metal makes a water hammer spreading out into the desired direction.

The same when you splash onto water with a flat back.

According to wiki the mentioned Shkval launch speed is just ~25 m/s.
If you shoot a railgun shell into the water at, say, 1000 m/s speed, when the shell meets the water you can get pressure ~ 1030 * 1000 * 1400 = 1.4 GPa, which is several times greater than a steel ultimate tensile strength.
So, an underwater shot would hit your own submarine like a depth charge.

Edited by kerbiloid
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6 minutes ago, kerbiloid said:

Then make it flat and let it bounce.

  Reveal hidden contents

hqdefault.jpg


When an incompressible fluid flow meets an immovable barrier, a "water hammer" effect happens.
It causes immediate local growth of pressure up to ~ (FluidDensity * FlowVelocity * SoundSpeedInTheFluid) value.
That's why the hydraulic valves have to be closed gradually, otherwise you get a water hammer in your pipeline where the valve stops the water flow, and this can must burst your pipe.
A cumulative shell also works this way, you get a super-high local pressure when the metal funnel gets collapsed under the external explosion pressure, and its liquified metal makes a water hammer spreading out into the desired direction.

According to wiki the mentioned Shkval has launch speed just ~25 m/s.
If you shoot a railgun shell into the water at, say, 1000 m/s speed, when the shell meets the water you can get pressure ~ 1030 * 1000 * 1400 = 1.4 GPa, which is several times greater than a steel ultimate tensile strength.
So, an underwater shot would hit your own submarine like a depth charge.

Indeed, high velocity is not rally compatible with water. Schkval is an outlier, and even then, considering its power, it "only" reaches a couple hundred knots or so.

***

Modern weapons are very advanced, surprisingly so. It always "amuses" (for want of a better word) me when people rave about how drones are going to end us all, or how armed robots are super-scary.

Torpedos are literally tiny robot killers, you release them and they speed away, find and identify targets and attempt to kill them.

AA missiles are literally tiny robot aircraft which do the same, highly autonomous.

Each have capabilities orders of magnitude greater than their manned counterpart.

Some AG missiles will search an area for a defined target or targets using multiple sensors (many weapons are turning up now with combined radar and IR sensor suites), send imaging data back to base for final ID (including high speed footage from the last second or so before impact to aid BDA) or even manual re-targetting and can abort to a safe area should a target not be located. Some weapons can attack multiple targets or loiter at altitude for one to turn up. Some weapons have multiple deployable warheads and can decide themselves how best to employ them.

We already have terminators among us, its just they dont look like the ones from the movies - because ours are more efficient killers.

Who would win in a fight? A T-101 model combat mechanoid or an autonomous, supersonic, brimstone missile with imaging millimetre radar, search algorithms and a 14lb shaped charge warhead capable of defeating modern MBT armours?

The reason Skynet wins is because of its control over nuclear weapons, not because terminators and other robot killing machines are particularly scary or unusual.

/weird random rant

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24 minutes ago, p1t1o said:

Indeed, high velocity is not rally compatible with water. Schkval is an outlier, and even then, considering its power, it "only" reaches a couple hundred knots or so.

***

Modern weapons are very advanced, surprisingly so. It always "amuses" (for want of a better word) me when people rave about how drones are going to end us all, or how armed robots are super-scary.

Torpedos are literally tiny robot killers, you release them and they speed away, find and identify targets and attempt to kill them.

AA missiles are literally tiny robot aircraft which do the same, highly autonomous.

Each have capabilities orders of magnitude greater than their manned counterpart.

Some AG missiles will search an area for a defined target or targets using multiple sensors (many weapons are turning up now with combined radar and IR sensor suites), send imaging data back to base for final ID (including high speed footage from the last second or so before impact to aid BDA) or even manual re-targetting and can abort to a safe area should a target not be located. Some weapons can attack multiple targets or loiter at altitude for one to turn up. Some weapons have multiple deployable warheads and can decide themselves how best to employ them.

We already have terminators among us, its just they dont look like the ones from the movies - because ours are more efficient killers.

Who would win in a fight? A T-101 model combat mechanoid or an autonomous, supersonic, brimstone missile with imaging millimetre radar, search algorithms and a 14lb shaped charge warhead capable of defeating modern MBT armours?

The reason Skynet wins is because of its control over nuclear weapons, not because terminators and other robot killing machines are particularly scary or unusual.

/weird random rant

This, the upcoming generation of robot weapons will be focused on finding the enemy, not so much killing them.

Benefit of armed drones is that they can patrol an area at all time hitting targets of opportunity or give patrols some air support. They don't have much firepower, they don't need it much as you can always get an fighter jet but that might take an hour. 
Say you assume enemy is hiding in an house, you have it pretty surrounded, house can also be mined, clearing it with infantry is dangerous and they have to go slow to avoiding it being even more dangerous. 
So you send in an ground drone, its better armored than soldiers and you don't care so much if it get destroyed. 
Just as the terminators from the movie, skynet had other weapons with more firepower. 

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Ten years later one will be fishing.
Once he has caught a fish, it says to the fisher:

"Attention! You just have captured the property of Naval Forces.
Please, release it back to the sea, lake, river or another body of water, which you have taken it from.
Our officer will contact you soon. Thank you for co-operation.
Click. Click. Click.
Caution! The self-destruct sequence will be initiated in 10... 9... 8... ..."

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15 minutes ago, magnemoe said:

This, the upcoming generation of robot weapons will be focused on finding the enemy, not so much killing them.

Benefit of armed drones is that they can patrol an area at all time hitting targets of opportunity or give patrols some air support. They don't have much firepower, they don't need it much as you can always get an fighter jet but that might take an hour. 
Say you assume enemy is hiding in an house, you have it pretty surrounded, house can also be mined, clearing it with infantry is dangerous and they have to go slow to avoiding it being even more dangerous. 
So you send in an ground drone, its better armored than soldiers and you don't care so much if it get destroyed. 
Just as the terminators from the movie, skynet had other weapons with more firepower. 

I didnt mean to imply that drones are not effective, only that we've had drones for a lot longer than we've had "drones" if you know what I mean, which means that becoming paranoid about the rise of "drones" is worse than pointless.

And the comparison to skynet - we have the capability to build skynets army today, it didnt have access to weaponry any more dangerous than that we already have. (ok they had plasma rifles in the 40W range, but thats just another infantry weapon, not a game changer like timed explosive ammunition, say). What we saw in the movies was the cleanup of the last 1% of living humans, it was the nukes that won the war.

Sophisticated, autonomous, robotic weapons are nothing new, is my point. With their superiority over a standard model T-101 combat mechanoid as an amusing aside :wink:

Anyhoo...a little OT.

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