How will anti submarine aircraft deal with submarine mounted laser weapon?

[Ronny]

The U.S. Navy's Virginia Class attack submarines are formidable weapons platforms. apparently they are to be the first subs in the world armed with a powerful laser as well. Documents suggest that the High Energy Laser (HEL) could be incredibly powerful, around 300 kilowatts. And eventually be up to 500 kilowatts. The power will come from the submarine’s nuclear reactor which has a capacity of 30 megawatts. It is suggested that the laser turret will be mounted on the periscope. When they submerged, submarines are invisible to radar, visual and thermal sensors and they can't be attacked by anti ship missile, bombs or cannon. So they can only be detected from very short range with sonobuoys and attacked by very slow weapons such as torpedo or mines . On the other hand, with high energy laser weapon, submarine can attack at speed of light, their weapon will have infinite shots andoptical sensor is virtually immune to jamming. So what is the possible counter/weapons that anti submarine helicopter, marine patrol aircraft and carrier jet fighter can take to deal with this newborn threat?

 

[Jason Dykstra (Wyvern)]

Mirrors

 

[kaiserd]

From what source has this come?
Please don’t say “Documents”.

 

[Jemiba]

From a well known SPF member, I think, as indicated in the lower left corner.

https://www.forbes.com/sites/hisutt...rm-attack-submarines-with-high-energy-lasers/

 

[stealthflanker]

and the sub must go in relatively shallow depth, perhaps even periscope depth. Extend the mast which have like 1 Sqm of RCS and remain for the whole duration of the engagement. Assuming 2.5 micron of laser with 1 m mast... one can down an aircraft (target hardness of some 25 Kj/sqcm) In 10 seconds and 20 Km. But well How do the sub get the target designation in the first place. ? and given the distance.. Not gonna put much faith on stealth as soon as the mast extended.

This basically a "deep magazine" version of Project Moraine.

 

[Ronny]

and the sub must go in relatively shallow depth, perhaps even periscope depth. Extend the mast which have like 1 Sqm of RCS and remain for the whole duration of the engagement.

https://pdfs.semanticscholar.org/edd8/1c99cb57c9c07de3b45021d423160407984b.pdf

Assuming 2.5 micron of laser with 1 m mast... one can down an aircraft (target hardness of some 25 Kj/sqcm) In 10 seconds and 20 Km. But well How do the sub get the target designation in the first place. ? and given the distance.. Not gonna put much faith on stealth as soon as the mast extended.

This basically a "deep magazine" version of Project Moraine.

That base on the laser power of 500 kW correct?
I think the power output can go a lot higher because even YAL-1 can go up to 1 MW while a nuclear submarine has 30 MW nuclear reactor and infinite cooling from ocean water
The laser can blind pilot almost instantaneously, and the ship can detect aircraft with optical system

 

[stealthflanker]

That base on the laser power of 500 kW correct?
I think the power output can go a lot higher because even YAL-1 can go up to 1 MW while a nuclear submarine has 30 MW nuclear reactor and infinite cooling from ocean water
The laser can blind pilot almost instantaneously, and the ship can detect aircraft with optical system

300 KW. 500 KW with same parameter adds like 10 km so 30 Km range But this does not answer on how to get the designation in the first place. Unless the submarine is already surfacing and like a WW 2 scenario, attempting to escape detection. Or it's from the start putting its mast scanning the skies... but this raises question on why not having the laser on surface ship instead if such mission is envisaged.

Laser can be big So is the submarine. The laser generator would be big too to compensate for the lack of aperture area. This in turn requires the submarine to have Hull "insert" for the laser generator and the respective "piping" or fiber optic required for actually transmitting the beam to the mast. All of this need to be cooled too and the cooling grow along with the power. means heavier equipment and larger volume required to support them.

Since a submarine requires to maintain balance between its volume vs density (As dictated by Law of Archimedes) Any addition to equipment etc will change this Balance. The laser equipment can be lightweight but it could occupy considerable volume, more volume leads to requirement for the submarine to be lengthened and then ballasted by addition of lead mine or if the laser is chemical based, compensation tank to account for the laser fuel consumption. It is unfortunately not just simply put the laser and power and cooling it.

And regarding blinding the pilot.. i dont think so as with the parameters defined before (2.5 micron wavelength and 1 m aperture) The beam diameter is about 18 cm, one will have to point the beam to the cockpit to actually hit the pilot. One can get bigger beam diameter by using longer wavelength but this increase power requirement as larger beam area means lesser energy being deposited on target.

Countermeasure for aircraft would be by usual means, like evading, and accept some damage maybe. Basically not be a steady target. Or itself having Radar or Laser warning receiver. As this laser may still require some means to calculate distance to its target. This achieved by radar or laser range finder. Then business usual by dropping torpedo or other ASW means.

 

[Hood]

How will anti submarine aircraft deal with submarine mounted laser weapon?

Send a UAV and drop a homing torpedo. Though in fairness a parachute-retarded torpedo would be relatively easy meat for a laser.

Wouldn't thermal blooming be an issue so close to the surface of the sea?

 

[Ronny]

300 KW. 500 KW with same parameter adds like 10 km so 30 Km range But this does not answer on how to get the designation in the first place. Unless the submarine is already surfacing and like a WW 2 scenario, attempting to escape detection. Or it's from the start putting its mast scanning the skies... but this raises question on why not having the laser on surface ship instead if such mission is envisaged.

Laser can be big So is the submarine. The laser generator would be big too to compensate for the lack of aperture area. This in turn requires the submarine to have Hull "insert" for the laser generator and the respective "piping" or fiber optic required for actually transmitting the beam to the mast. All of this need to be cooled too and the cooling grow along with the power. means heavier equipment and larger volume required to support them.

Since a submarine requires to maintain balance between its volume vs density (As dictated by Law of Archimedes) Any addition to equipment etc will change this Balance. The laser equipment can be lightweight but it could occupy considerable volume, more volume leads to requirement for the submarine to be lengthened and then ballasted by addition of lead mine or if the laser is chemical based, compensation tank to account for the laser fuel consumption. It is unfortunately not just simply put the laser and power and cooling it.

And regarding blinding the pilot.. i dont think so as with the parameters defined before (2.5 micron wavelength and 1 m aperture) The beam diameter is about 18 cm, one will have to point the beam to the cockpit to actually hit the pilot. One can get bigger beam diameter by using longer wavelength but this increase power requirement as larger beam area means lesser energy being deposited on target.

Countermeasure for aircraft would be by usual means, like evading, and accept some damage maybe. Basically not be a steady target. Or itself having Radar or Laser warning receiver. As this laser may still require some means to calculate distance to its target. This achieved by radar or laser range finder. Then business usual by dropping torpedo or other ASW means.

I was thinking about a higher power, with 30 MW nuclear reactor it is possible to have 10-15 MW laser, they will burn through fuselage like butter
If they can put 2 MW on a 400 tons aircraft then putting 15 MW laser on 7900 tons submarine sound like an easy task, after all they can put ballistic missiles on submarine and those thing weight dozen tons at least.
The submarine can pop its periscope up and find aircraft with FLIR when it detect the sonoboys ping.

 

[Ronny]

How will anti submarine aircraft deal with submarine mounted laser weapon?

Send a UAV and drop a homing torpedo. Though in fairness a parachute-retarded torpedo would be relatively easy meat for a laser.

Wouldn't thermal blooming be an issue so close to the surface of the sea?

I think the UAV is dead meat for DEW

 

[Scott Kenny]

I'm trying to figure out how they're going to push 300kw through a 4" or less aperture without melting anything.

I was thinking about a higher power, with 30 MW nuclear reactor it is possible to have 10-15 MW laser, they will burn through fuselage like butter
If they can put 2 MW on a 400 tons aircraft then putting 15 MW laser on 7900 tons submarine sound like an easy task, after all they can put ballistic missiles on submarine and those thing weight dozen tons at least.

Subs don't have the spare generating capacity to continuously run a laser that powerful, unless they're building a variation of the Virginia-class with turbo-electric drive. I saw the SSTGs on the Ohio class boats I was on running with ~50 spare kW. (generator capacity was a nice plaque, current output was a digital display. Example: a 10MW generator showing current output in the upper 9900kW range, times 2 generators)

As long as you are running steam turbines as the ship's main engines, you will not have access to most of the reactor's power for electrical loads. Example from the Ohio-class again: per wiki, the boat has a 220MWth reactor, driving two main engines of 26MW each, total of about 52MW; plus a pair of Ship's Service Turbine Generators of about 10MW each, total of about 20MW. Total steam consumption of about 72MW. the rest of the thermal production is waste heat, dumped into the ocean.

The submarine can pop its periscope up and find aircraft with FLIR when it detect the sonoboys ping.

If you're hearing the pings, you're already detected.

If your ESM stack is detecting an APS-137 radar for any length of time at all, you're detected, that radar has an adjustable output so that the plane can close in while keeping the same power received at the sub.

 

[spender]

Submarines primary weapon is stealth. The sub wouldn't know the plane was there unless it heard sonobuoys or torpedo drop. I'm sure the Russians or Chinese ASW aircraft will have a version of Poseidon's winged torpedo. https://www.thedrive.com/the-war-zone/navy-p-8-poseidon-can-now-drop-winged-torpedos-in-combat When hearing acoustics the sub would have to choose to go deep or climb to periscope depth to counter-attack. I think most sub captains would go deep if possible, but there are parts of the SCS or Arctic where they couldn't, and would have fight back.

 

[Scott Kenny]

Submarines primary weapon is stealth. The sub wouldn't know the plane was there unless it heard sonobuoys or torpedo drop. I'm sure the Russians or Chinese ASW aircraft will have a version of Poseidon's winged torpedo. https://www.thedrive.com/the-war-zone/navy-p-8-poseidon-can-now-drop-winged-torpedos-in-combat When hearing acoustics the sub would have to choose to go deep or climb to periscope depth to counter-attack. I think most sub captains would go deep if possible, but there are parts of the SCS or Arctic where they couldn't, and would have fight back.

Exactly. This is the last scream of defiance when a sub cannot run.

 

[Ronny]

I'm trying to figure out how they're going to push 300kw through a 4" or less aperture without melting anything.

Maybe they use the vast ocean water as coolent?

Subs don't have the spare generating capacity to continuously run a laser that powerful, unless they're building a variation of the Virginia-class with turbo-electric drive. I saw the SSTGs on the Ohio class boats I was on running with ~50 spare kW. (generator capacity was a nice plaque, current output was a digital display. Example: a 10MW generator showing current output in the upper 9900kW range, times 2 generators)

As long as you are running steam turbines as the ship's main engines, you will not have access to most of the reactor's power for electrical loads. Example from the Ohio-class again: per wiki, the boat has a 220MWth reactor, driving two main engines of 26MW each, total of about 52MW; plus a pair of Ship's Service Turbine Generators of about 10MW each, total of about 20MW. Total steam consumption of about 72MW. the rest of the thermal production is waste heat, dumped into the ocean.

So when the submarine move quickly, most of the energy produced will be used by the engine. But how about when it move very slow to be stealthy?. Or when it just short of stay stationary for an ambush?

If you're hearing the pings, you're already detected.
If your ESM stack is detecting an APS-137 radar for any length of time at all, you're detected, that radar has an adjustable output so that the plane can close in while keeping the same power received at the sub.

I honestly don’t think submarine are detected when they can hear the ping from enemy helicopter. Sound wave from active sonar need to travel out then back, to complete the detection. By contrast, passive sonar just need to receive the sound wave travel 1 way . According to the fourth square law, with same sensitivity, the passive sonar will away detect the active sonar first (it basically the same when RWR detect radar).

 

[Scott Kenny]

Maybe they use the vast ocean water as coolent?

I don't know that you can transfer that much heat into water that quickly. And if you can dump that much heat into the water that quickly, you're now leaving a great big thermal trace on the water for more people to come to the party and ruin your day!

So when the submarine move quickly, most of the energy produced will be used by the engine. But how about when it move very slow to be stealthy?. Or when it just short of stay stationary for an ambush?

Only for a turbo-electric drive sub, one that uses electric motors to power the screw(s) all the time. Those will have spare generating capacity when moving slowly. The others have more or less the same electrical consumption whether they're at the hover or at flank speed.

I honestly don’t think submarine are detected when they can hear the ping from enemy helicopter. Sound wave from active sonar need to travel out then back, to complete the detection. By contrast, passive sonar just need to receive the sound wave travel 1 way . According to the fourth square law, with same sensitivity, the passive sonar will away detect the active sonar first (it basically the same when RWR detect radar).

Yes, the sonar pings CAN be detected at greater range than they can detect you. Unless someone is playing games with their emitter power levels like I talked about with the APS-137.

Submariner's basic rule of thumb: If you hear sonar pinging away, leave!

 

[Ronny]

I don't know that you can transfer that much heat into water that quickly. And if you can dump that much heat into the water that quickly, you're now leaving a great big thermal trace on the water for more people to come to the party and ruin your day!

I'm not aware any particular submarine finding others by heat signature, and beside, consider the vast of the ocean and the water specific heat capacity, the heat seem negligible. We already have megawatt airborne laser such as YAL-1, it has no issue with heat sink even though thin air conduct heat much worse compared to water

Only for a turbo-electric drive sub, one that uses electric motors to power the screw(s) all the time. Those will have spare generating capacity when moving slowly. The others have more or less the same electrical consumption whether they're at the hover or at flank speed.

How come?

Yes, the sonar pings CAN be detected at greater range than they can detect you. Unless someone is playing games with their emitter power levels like I talked about with the APS-137.

Submariner's basic rule of thumb: If you hear sonar pinging away, leave!

Unless you already know the submarine exact location before you transmit, how can you play with the power level though?. At whatever power level for the active sonar or radar, the range that they can detect a submarine always shorter than the range that the passive sonar or ESM on submarine can detect the pulse.

 

[A Tentative Fleet Plan]

I'm not aware any particular submarine finding others by heat signature, and beside, consider the vast of the ocean and the water specific heat capacity, the heat seem negligible. We already have megawatt airborne laser such as YAL-1, it has no issue with heat sink even though thin air conduct heat much worse compared to water

If the submarine is dumping a significant amount of heat in the water to run a laser to shoot down an MPA, then the main issue of the IR bloom is revealing the submarine to the MPA and other aircraft and potentially surface ships IRST equipment.

How come?

Because most submarines have no way of using the full power of the reactor for electrical generation, in the same way that some surface combatants can't make use of the power generation capabilities of their machinery. The Steam Turbines of most SSNs, and the Gas Turbines/Diesels of most modern warships are mechanically connected to the propeller shaft, not to any means of generating electrical power.

Vessels with steam turbines can draw off some steam to drive turbogenerators, although the power that this can generate is limited by the number and capacity of the turbogenerators, and in submarines would be used for the hotel loads plus running the sonars and combat system. Most modern surface ships use separate gas turbine or diesel generators for this purpose.

In a warship or submarine with Integrated Electric Propulsion, the vessel's main powerplant drives generators, which in turn power an electric motor connected to the vessel's screw(s), as well supporting the radars/sonars, combat system and hotel loads. As such vessels with IEP can make full use of the theoretical power of their main propulsion powerplants.

 

[Scott Kenny]

I'm not aware any particular submarine finding others by heat signature, and beside, consider the vast of the ocean and the water specific heat capacity, the heat seem negligible. We already have megawatt airborne laser such as YAL-1, it has no issue with heat sink even though thin air conduct heat much worse compared to water

It's not the sub detecting other subs by heat sig, it's the MPA detecting your sub by heat sig.

How come?

Ships without IEP only have so much generator capacity installed, the rest of their potential power is directly connected to the propeller shaft(s). Per my earlier example, say ~20MWe. That runs all the hotel load and the combat systems, and has a little bit of excess to handle any startup loads for intermittent things like a 400hz motor-generator set or the laundry.

For example: your car has a 200hp engine, and a 75amp alternator. If you try to draw more than 1000w of electricity because you installed a bigger stereo in the car, it just can't feed it. Even though that 75amp alternator only consumes about 1.5hp, you just can't divert more of the 200hp total into the alternator.​

A ship with IEP has the full capacity of their powerplant being used to make electricity, which can then be sent to electric motors on the propeller shafts, hotel load, combat systems, etc. The car equivalent of this is a series hybrid, where you have a large generator driving electric motor(s) at the axles.

Unless you already know the submarine exact location before you transmit, how can you play with the power level though?. At whatever power level for the active sonar or radar, the range that they can detect a submarine always shorter than the range that the passive sonar or ESM on submarine can detect the pulse.

It's up to operator's skill at that point, and the operators in the USN tend to have a lot of practice. As a rough rule of thumb, three "possible periscopes" in roughly the same location is enough to have an operator guiding the plane closer and turning the power down.

 

[Ronny]

It's not the sub detecting other subs by heat sig, it's the MPA detecting your sub by heat sig.

Before the submarine firing the laser, the only IR signature would be the small/ cold periscope poke out of water which is a much smaller IR signature compared to the airplane flying on sky background. So I think there is much higher chance for the submarine to detect the aircraft rather than vice versa. Once the submarine use the laser for engagement, the water will heat up alot and make it easier to detect. But at that point, the MPA is already being engaged by a weapon moving at light speed. The MPA likely being shotdown before it can get close enough to drop torpedo on the submarine. Even if MPA use torpedo with wing kit such as HAAWC, there is nothing stopping the submarine from destroying that torpedo by its laser either, it should be quite simple given that laser weapon are fast enough to even engage artillery round

Ships without IEP only have so much generator capacity installed, the rest of their potential power is directly connected to the propeller shaft(s). Per my earlier example, say ~20MWe. That runs all the hotel load and the combat systems, and has a little bit of excess to handle any startup loads for intermittent things like a 400hz motor-generator set or the laundry.

For example: your car has a 200hp engine, and a 75amp alternator. If you try to draw more than 1000w of electricity because you installed a bigger stereo in the car, it just can't feed it. Even though that 75amp alternator only consumes about 1.5hp, you just can't divert more of the 200hp total into the alternator.​

A ship with IEP has the full capacity of their powerplant being used to make electricity, which can then be sent to electric motors on the propeller shafts, hotel load, combat systems, etc. The car equivalent of this is a series hybrid, where you have a large generator driving electric motor(s) at the axles.

That make sense, is there any nuclear powered submarine with IEP at the moment?

It's up to operator's skill at that point, and the operators in the USN tend to have a lot of practice. As a rough rule of thumb, three "possible periscopes" in roughly the same location is enough to have an operator guiding the plane closer and turning the power down.

I mean, let say for example (1 made up these number to illustrate the point).
At average transmit power of 2 kW, the radar on MPA can detect the submarine scope from 30 km. At average transmit power of 0.12 kW, the radar on MPA can detect the submarine periscope from 15 km. So if you detect the periscope from 30 km out, you can gradually reduce your radar transmitting power as your aircraft get closer. My problem is that: the ESM on submarine will always detect the radar from greater distance, so if your radar power is 2 kW, then the submarine ESM can already detect the aircraft from 60 km. If radar power reduced to 0.12 kW, the ESM can still detect the aircraft from 30 km. At no point the radar can detect the submarine before itself can be detected by ESM system. Same case for active vs passive sonar

 

[Ronny]

If the submarine is dumping a significant amount of heat in the water to run a laser to shoot down an MPA, then the main issue of the IR bloom is revealing the submarine to the MPA and other aircraft and potentially surface ships IRST equipment.

But once the airplane being engaged by laser, it won’t live much longer. Probably 10-15 seconds top. Ways before it can retaliate with torpedo. Then after the short engagement, the submarine can easily go underwater then run. Or simply use the laser to blind FLIR sensor

 

[A Tentative Fleet Plan]

But once the airplane being engaged by laser, it won’t live much longer. Probably 10-15 seconds top. Ways before it can retaliate with torpedo. Then after the short engagement, the submarine can easily go underwater then run. Or simply use the laser to blind FLIR sensor

The aircraft is unlikely to be alone, and will be data-linked with other aircraft, ships and shore facilities. Revealing your position to an MPA hunting you also reveals your position to everything that shares a data-link with the MPA.

 

[Ronny]

The aircraft is unlikely to be alone, and will be data-linked with other aircraft, ships and shore facilities. Revealing your position to an MPA hunting you also reveals your position to everything that shares a data-link with the MPA.

Ship based anti submarine weapons have pretty short range since they often used small size torpedo like Mark54 with range around 10-12 km maximum, even the rocket launched torpedo such as RUM-139 is limited to around 22 km, I don’t think they could be of much help to the MPA when the MPA is being attacked by submarine laser weapon.
In the past, helicopter and MPA are pretty much the bane of submarine since they can pretty much attack the submarine with immunity. But with laser weapon on submarine, the situation is in reversed

 

[A Tentative Fleet Plan]

Ship based anti submarine weapons have pretty short range since they often used small size torpedo like Mark54 with range around 10-12 km maximum, even the rocket launched torpedo such as RUM-139 is limited to around 22 km, I don’t think they could be of much help to the MPA when the MPA is being attacked by submarine laser weapon.

UUM/RUM-125B was intended to go 65km, and the nuclear RUM/UUM-125A was intended 185km, and that was 30 years ago, the Russian RPK-6 & 7 have ranges claimed ranges around 100km, and India claims a range of 643km for their SMART (although I doubt that), RUM-139 is hardly the be-all and end-all of stand-off ASW weapons.

Depends how close other assets are to the MPA, which if shot down will provide a flaming datum on the location of the submarine regardless. Of course if Submarines get lasers, MPAs may get wing-kits for the their Lightweight torpedoes, and stand-off weapons were proposed for MPAs and ASW Helicopters as early as the 1960s,so there's no practical reason to rule out something like that now.

In the past, helicopter and MPA are pretty much the bane of submarine since they can pretty much attack the submarine with immunity. But with laser weapon on submarine, the situation is in reversed

They can still attack the submarines with their own weapons, and the one advantage over the submarine they have is that they are operating with, and are in regular communication with other assets. The submarine is most likely operating by itself, and taking a pot-shot at an MPA endangers whatever other mission it is carrying out. Much better to avoid detection if at all possible.

 

[Ronny]

UUM/RUM-125B was intended to go 65km, and the nuclear RUM/UUM-125A was intended 185km, and that was 30 years ago, the Russian RPK-6 & 7 have ranges claimed ranges around 100km, and India claims a range of 643km for their SMART (although I doubt that), RUM-139 is hardly the be-all and end-all of stand-off ASW weapons.

Depends how close other assets are to the MPA, which if shot down will provide a flaming datum on the location of the submarine regardless. Of course if Submarines get lasers, MPAs may get wing-kits for the their Lightweight torpedoes, and stand-off weapons were proposed for MPAs and ASW Helicopters as early as the 1960s,so there's no practical reason to rule out something like that now.

RUM-125 was never produced as far as I know, and even if they get produced, their top speed is only Mach 1.5, which should be simple enough for the laser to destroy as current laser air defense can already track and destroy supersonic missile/rocket
Wing kit for light weight torpedo only solve the issue of range, it still doesn’t solve the issue with speed, laser air defense should have no issue destroying the winged torpedo which is both fragile and slow target

They can still attack the submarines with their own weapons, and the one advantage over the submarine they have is that they are operating with, and are in regular communication with other assets. The submarine is most likely operating by itself, and taking a pot-shot at an MPA endangers whatever other mission it is carrying out. Much better to avoid detection if at all possible.

I think one of the key advantage that laser weapon offer is that they can act as both offense and defensive system. In offensive, they can’t be out maneuved, the effect is instant, they can easily blind IIR sensor as well. In defensive, they pretty much have unlimited shot, instant reaction time. Pretty much every single thing the MPA can throw at the submarine are very easily destroyed by laser

 

[A Tentative Fleet Plan]

RUM-125 was never produced as far as I know, and even if they get produced, their top speed is only Mach 1.5, which should be simple enough for the laser to destroy as current laser air defense can already track and destroy supersonic missile/rocket

RUM-125 is a good example of the state of the art, probably a better weapon for comparison given its performance is closer to the RPK-6 and RPK-7 than the RUM-139. State competitors are unlikely to copy the RUM-139 when there are weapons with vastly greater performance.

The laser is not going to shoot them down, as Submarines do not carry large phased array radars for missile defence, and stand-off ASW are relatively high-performance air targets, requiring very capable systems to track and target them (the UUM-44 SUBROC, or weapons like it were one of the drivers behind the development of Typhon, the predecessor to AEGIS). Submarines by and large do not carry large powerful 3D air defence radars, at least aside from the USS Triton, in fact I would be surprised if the radars that submarines do carry are any more powerful than commercial navigation sets (since that is the only role a radar on a submarine is likely to be used for). As ever, the most important thing is target acquisition, and you need a means of wide area search to engage any kind of aerial target.

Not only do you now want the submarine to have periscope mast raised, a large IR bloom from the laser, you now want it to be continuously radiating from a large phased array radar?

Wing kit for light weight torpedo only solve the issue of range, it still doesn’t solve the issue with speed, laser air defense should have no issue destroying the winged torpedo which is both fragile and slow target.

There's only one laser, and the MPA carries several torpedoes, and given the submarine will be sailing at very low speeds, with a mast extended, if only one makes it into the water you are dead.

I think one of the key advantage that laser weapon offer is that they can act as both offense and defensive system. In offensive, they can’t be out maneuved, the effect is instant, they can easily blind IIR sensor as well. In defensive, they pretty much have unlimited shot, instant reaction time. Pretty much every single thing the MPA can throw at the submarine are very easily destroyed by laser

Several MPAs, ASW Helicopters and surface ships however, are a significant threat, and that is the likely result of attempting to take a shot at an MPA with a laser.

Why is a submarine attempting to shoot at an MPA when it's very likely that it will still remain undetected? And if it is detected and is merely trying to prevent the MPA harassing it, coming up to periscope depth and raising the laser mast will put it in a vary vulnerable position, especially in a situation where it is engaged by the MPA at a shallow depth and yet is still too deep the raise the laser mast.

 

[Ronny]

RUM-125 is a good example of the state of the art, probably a better weapon for comparison given its performance is closer to the RPK-6 and RPK-7 than the RUM-139. State competitors are unlikely to copy the RUM-139 when there are weapons with vastly greater performance.

The laser is not going to shoot them down, as Submarines do not carry large phased array radars for missile defence, and stand-off ASW are relatively high-performance air targets, requiring very capable systems to track and target them (the UUM-44 SUBROC, or weapons like it were one of the drivers behind the development of Typhon, the predecessor to AEGIS). Submarines by and large do not carry large powerful 3D air defence radars, at least aside from the USS Triton, in fact I would be surprised if the radars that submarines do carry are any more powerful than commercial navigation sets (since that is the only role a radar on a submarine is likely to be used for). As ever, the most important thing is target acquisition, and you need a means of wide area search to engage any kind of aerial target.

Not only do you now want the submarine to have periscope mast raised, a large IR bloom from the laser, you now want it to be continuously radiating from a large phased array radar?

Laser weapons are not the same as kinetic weapon like missiles or bullets. Kinetic weapon need significant time to arrive at target area, so you need radar to tell you how far the target is, how fast it is moving, so that your missile can fly toward the location that target will be in the future (lead intercept). By contrast, laser literally engage target at speed of light so you don’t need to lead intercept target. It is basically point and shot weapon. That why laser weapon such as Iron beam or YAL-1 only need IIR system to control them, because they only need to know target direction. Big rocket is very easily to detect amd track with IIR system (as demonstrated by the tiny DAS sensor on F-35)

There's only one laser, and the MPA carries several torpedoes, and given the submarine will be sailing at very low speeds, with a mast extended, if only one makes it into the water you are dead.



Several MPAs, ASW Helicopters and surface ships however, are a significant threat, and that is the likely result of attempting to take a shot at an MPA with a laser.

Why is a submarine attempting to shoot at an MPA when it's very likely that it will still remain undetected? And if it is detected and is merely trying to prevent the MPA harassing it, coming up to periscope depth and raising the laser mast will put it in a vary vulnerable position, especially in a situation where it is engaged by the MPA at a shallow depth and yet is still too deep the raise the laser mast.

The problem with winged torpedo is that they are ways too slow, they likely gliding at low subsonic speed like Mach 0.4-0.5, they would need around 300 seconds to reach the submarine location from 50 km. Whereas it only take 2-3 seconds to burn the wing and make torpedo drop like a stone.
Anyway, if the submarine can hide, it would hide, but iam thinking about situation that the submarine detect the sonobouy ping that is too close, close enough to make the commander think he will eventually get detected. He can just pop up, kill the MPA, then retreat

 

[A Tentative Fleet Plan]

Laser weapons are not the same as kinetic weapon like missiles or bullets. Kinetic weapon need significant time to arrive at target area, so you need radar to tell you how far the target is, how fast it is moving, so that your missile can fly toward the location that target will be in the future (lead intercept). By contrast, laser literally engage target at speed of light so you don’t need to lead intercept target. It is basically point and shot weapon. That why laser weapon such as Iron beam or YAL-1 only need IIR system to control them, because they only need to know target direction. Big rocket is very easily to detect amd track with IIR system (as demonstrated by the tiny DAS sensor on F-35)

YAL-1 would have been cued by a whole host of radars and satellites onto its target. It was not a stand-alone self-contained weapons system. Of course it was a boost-phase system, and was engaging larger targets at a much more vulnerable point in their flight.

The problem with winged torpedo is that they are ways too slow, they likely gliding at low subsonic speed like Mach 0.4-0.5, they would need around 300 seconds to reach the submarine location from 50 km. Whereas it only take 2-3 seconds to burn the wing and make torpedo drop like a stone.
Anyway, if the submarine can hide, it would hide, but iam thinking about situation that the submarine detect the sonobouy ping that is too close, close enough to make the commander think he will eventually get detected. He can just pop up, kill the MPA, then retreat

If the MPA has detected the submarine with an active sonobuoy then it is probably closer than 50 km. The detected submarine has to get up to periscope depth before the MPA can drop a torpedo on it, bearing in mind that the the submarine is actively making itself more likely to be detected (if the sonobuoy might detect it at depth, it will certainly detect the submarine when it's shallow) and attacked before it gets to periscope depth.

Again, even if the submarine succeeds in its plan of shooting down the MPA, it has immediately localised it's position, and given every other MPA, ASW helicopter and ship in the area somewhere to search. If the submarine is trying to escape it's made its job much harder.

 

[Ronny]

YAL-1 would have been cued by a whole host of radars and satellites onto its target. It was not a stand-alone self-contained weapons system. Of course it was a boost-phase system, and was engaging larger targets at a much more vulnerable point in their flight.

Actually, while YAL-1 can be connected to a whole host of radar and satellite, it will be the one that do the initial detection rather than being cued because it is a boost phase intercept system.
Ballistic missiles right after launch are still below radar horizon but can already be detected by AAS-42 sensor on YAL-1 because YAL-1 is at high altitude and much closer to target area compared to these long range anti ballistic missile radar.

If the MPA has detected the submarine with an active sonobuoy then it is probably closer than 50 km. The detected submarine has to get up to periscope depth before the MPA can drop a torpedo on it, bearing in mind that the the submarine is actively making itself more likely to be detected (if the sonobuoy might detect it at depth, it will certainly detect the submarine when it's shallow) and attacked before it gets to periscope depth.

Again, even if the submarine succeeds in its plan of shooting down the MPA, it has immediately localised it's position, and given every other MPA, ASW helicopter and ship in the area somewhere to search. If the submarine is trying to escape it's made its job much harder.

If the submarine is already detected, it can either wait till a torpedo dropped directly on top of it, or kill the MPA and the torpedo with laser. The second option is better.
Even if others MPA and ASW in the area know the general location of the submarine because a MPA is down, they still lacking in an effective weapon to kill it. Winged torpedo take too long and can be destroyed very quickly, it like trying to kill an AEGIS carrier but only armed with iron bomb

 

[A Tentative Fleet Plan]

Actually, while YAL-1 can be connected to a whole host of radar and satellite, it will be the one that do the initial detection rather than being cued because it is a boost phase intercept system.
Ballistic missiles right after launch are still below radar horizon but can already be detected by AAS-42 sensor on YAL-1 because YAL-1 is at high altitude and much closer to target area compared to these long range anti ballistic missile radar.

Notably not a position the submarine would be in. A 360 degree staring IRST would require the mast to be up, creating a large radar target, (and will probably require it's own mast, further increasing the radar signature). The weather conditions of the surface of the sea would also not be fully conducive to passive electro optical observation. Radars are still necessary if you want to look through clouds, or other atmospheric conditions.

If the submarine is already detected, it can either wait till a torpedo dropped directly on top of it, or kill the MPA and the torpedo with laser. The second option is better.

Or it can break contact with the MPA by presenting a narrow aspect to the sonobuoy, or perhaps more importantly, not getting detected by the active sonobuoy in the first place, by not getting too close to it. There are also other means of reducing the effectiveness of active sonars, including anechoic coating and shaping of the submarine hull to avoid this issue. Rising to periscope depth will ensure the submarine gets closer to any active sonobuoy, and will turn a possible contact into a definite contact. The MPA can fly over to the submarines position before it gets into position to use the laser (any depth below periscope depth) and sink the relatively slow shallow target with the weapons at its disposal.

Even if others MPA and ASW in the area know the general location of the submarine because a MPA is down, they still lacking in an effective weapon to kill it. Winged torpedo take too long and can be destroyed very quickly, it like trying to kill an AEGIS carrier but only armed with iron bomb

Your scenario was that the submarine would kill the MPA and then leg it, not duke it out with every aircraft and surface ship in the local area. Winged torpedoes coming from multiple directions simultaneously would saturate the submarine quickly, that is if it could even engage them in the first place without a radar, because gliding weapons with wing kits do not have large IR signatures, and some will be hard to spot. Again the submarine will be at periscope depth, and at low speed to avoid damaging the mast, so it will be in a terrible position to avoid any incoming torpedo that actually does make it into the water. Given the shallow depth and low speed of the submarine, the lightweight torpedoes will also have more effective range, and can be dropped considerably short of the submarine itself.

Alternatives available to the opponent could also include vectoring in a submarine of their own to engage the laser-equipped submarine. The opponent's submarine, freed from the constraints of having to stay at periscope, could exploit the acoustic advantages that greater depth brings, and sink it with a conventional heavyweight torpedo. Or getting a surface ship to engage the submarine with torpedoes, RBUs or their equivalent and potentially consider engaging the periscope with it's main gun, though these options do put it well within range or retaliation of the submarine.

AEGIS ships have phased arrays radars with missile data-links, and multiple illuminations, enabling to engage multiple targets simultaneously. They're also broadly speaking, not sufficient on their own against any kind of mass raid, hence why they operate in multiples, potentially as part of a carrier airgroup. They don't have a single laser, cued by FOV akin to looking down a straw of a bore-sighted electro-optical system.

Of course whilst this submarine is trying to attract the attention of every ASW unit in range, it's not doing the mission it was intended to do, whether that is SIGINT, attacking a convoy, engaging a land target with cruise missiles, inserting a special forces team, performing strategic ASW by sinking a boomer, whatever it is that mission has now been scrubbed, something which was by no means certain until the captain decided to try to beam an MPA.

 

[Scott Kenny]

Before the submarine firing the laser, the only IR signature would be the small/ cold periscope poke out of water which is a much smaller IR signature compared to the airplane flying on sky background. So I think there is much higher chance for the submarine to detect the aircraft rather than vice versa. Once the submarine use the laser for engagement, the water will heat up alot and make it easier to detect. But at that point, the MPA is already being engaged by a weapon moving at light speed. The MPA likely being shotdown before it can get close enough to drop torpedo on the submarine. Even if MPA use torpedo with wing kit such as HAAWC, there is nothing stopping the submarine from destroying that torpedo by its laser either, it should be quite simple given that laser weapon are fast enough to even engage artillery round

Nuclear subs also dump all their waste heat into the ocean, so there's a long strip of significantly-warmer water behind that funny stick poking out of the water.

That make sense, is there any nuclear powered submarine with IEP at the moment?

I think the French boats are running turbo-electric drives. Columbia class will, but isn't anywhere near the water yet.

I mean, let say for example (1 made up these number to illustrate the point).
At average transmit power of 2 kW, the radar on MPA can detect the submarine scope from 30 km. At average transmit power of 0.12 kW, the radar on MPA can detect the submarine periscope from 15 km. So if you detect the periscope from 30 km out, you can gradually reduce your radar transmitting power as your aircraft get closer. My problem is that: the ESM on submarine will always detect the radar from greater distance, so if your radar power is 2 kW, then the submarine ESM can already detect the aircraft from 60 km. If radar power reduced to 0.12 kW, the ESM can still detect the aircraft from 30 km. At no point the radar can detect the submarine before itself can be detected by ESM system. Same case for active vs passive sonar

So the ESM gets 1-2 chirps.

Standing policy for my subs on ESM hits from an APS-137 was go deep and break contact because of the dialed power training. Because otherwise you have ESM hits at low power, immediately followed by a 68hz tonal as the P3 roars overhead and drops buoys and/or torpedoes on top of you.

 

[publiusr]

Spacecraft might be a submarine’s best friend. A cloud of incoming—downward facing tungsten won’t be felt below the sea surface.

They shoot down at you…you shoot down at them.

 

[Scott Kenny]

Spacecraft might be a submarine’s best friend. A cloud of incoming—downward facing tungsten won’t be felt below the sea surface.

They shoot down at you…you shoot down at them.

That's very slow to arrive.

 

[publiusr]

The ASW also takes time to get in position.

Sats and subs may communicate in ways aircraft cannot monitor.

“ASW inbound…”

 

[Scott Kenny]

The ASW also takes time to get in position.

Sats and subs may communicate in ways aircraft cannot monitor.

“ASW inbound…”

What I mean is that from call for fire to impact, it's about 20-30 minutes for "dropped kinetics" to land. The satellite that would be dropping any kinetics is one on the far side of the planet from the craft calling for ortillery fire.

An orbital laser would be much more useful to provide AA coverage for submarines.