[Ultra-Tech] What would naval warfare at TL10 look like?

[Anthony]

Originally Posted by lwcamp

A ship, or an installation located near the water, could use water pumps to send a spray of water up around it for laser cover. However, this works both ways - the ship would not be able to see or shoot its own lasers out.

I don't think it would work with water, but it might with some other material. Air has a breakdown intensity at which it turns opaque; if you can adjust that down by mixing in something else, it would allow shooting out but not in.

[mlangsdorf]

Originally Posted by lwcamp

A ship, or an installation located near the water, could use water pumps to send a spray of water up around it for laser cover. However, this works both ways - the ship would not be able to see or shoot its own lasers out.

The ship can create gaps in the spray when it wants to attack, and the aircraft can't predict when the gaps are going to appear. It's like arrow-slits in a castle wall: yes, the attacker can shoot through them, but it's a lot harder for the attacker and easier for the defender.

Lasers aren't really efficient for penetrating armor as armor DR gets huge. Ships are going to have more armor than aircraft and more powerful lasers, because even a small ship is more than 10x as large as an aircraft. So aircraft lasers are going to have a much harder time damaging ships than ships are going to have damaging aircraft. Even if the water degrades the effectiveness of the ship's lasers by 90%, it probably comes out ahead because 10% of the aircraft's laser damage doesn't scuff the ship's paint but 10% of the ship's laser damage can harm the aircraft.

I'm also curious about the use of continuous sea sprays to cause hypersonic missiles to convert their kinetic energy into destruction prematurely. Hypersonic missiles depend on radical streamlining, and if they're not radically streamlined, they're not hypersonic, and if they're not hypersonic, they're not doing ridiculous amounts of damage. I suspect that predictive armor might also be a solution, using surface mount explosives to toss metal plates into the path of missiles and degrading their effectiveness that way.

[lwcamp]

Originally Posted by mlangsdorf

Ships are going to have more armor than aircraft and more powerful lasers, because even a small ship is more than 10x as large as an aircraft.

Unless, of course, the aircraft doesn't have an on-board laser at all, but just a beam collector to take the beam from a friendly ship, a beam cleaner, and then a beam pointer to re-emit the beam at the target.

Luke

[mlangsdorf]

Even if the aircraft has effectively as powerful a laser as the surface ship, or even a more powerful laser, it probably has substantially less armor: although fusion air-rams do really weird things to aircraft design by giving designers a ridiculous amount of power to play with, there probably isn't enough space on a typical airframe to put 12" of armor, and a much smaller vehicle means any penetration is more likely to hit something important.

So even if the aircraft can mount a more powerful laser, it's probably still coming out on the wrong side of the attacks to kill ratio, just because it's so much smaller. It may be possible to offset that with more aircraft, of course.

I would also be worried, as the aircraft operator, about what happens when the beam generator misses the beam collector: the beam generator is shooting a beam that can damage an armored warship, so if it hits any part of my airframe other than the beam collector, I will probably have problems. You say it's probably a solved problem at TL10, and maybe you don't need pinpoint accuracy on the beam collector, but I worry that an airframe moving in air is something of a chaotic system and the beam generator may not be able to adequately predict the movement of the aircraft, especially when the shooting starts.

[Fred Brackin]

Originally Posted by mlangsdorf

So even if the aircraft can mount a more powerful laser, it's probably still coming out on the wrong side of the attacks to kill ratio, just because it's so much smaller.

The surface ships are still on the wrong end of the "vulnerability" window. Their horizon is so limited that you need to continuously try and find ways to circumvent it for sensors and weapons.

With fusion air-rams it's possible that you might not have any use for surface ships any more. They're only support and logistics bases for other forces rather than primary combatants anyway. That's already true.

[lwcamp]

Originally Posted by mlangsdorf

Even if the aircraft has effectively as powerful a laser as the surface ship, or even a more powerful laser, it probably has substantially less armor: although fusion air-rams do really weird things to aircraft design by giving designers a ridiculous amount of power to play with, there probably isn't enough space on a typical airframe to put 12" of armor, and a much smaller vehicle means any penetration is more likely to hit something important.

So even if the aircraft can mount a more powerful laser, it's probably still coming out on the wrong side of the attacks to kill ratio, just because it's so much smaller. It may be possible to offset that with more aircraft, of course.

I figure the aircraft would not shoot the ship where it has armor. The most likely initial target will be the beam pointer telescopes of the ship, particularly the vulnerable parts where the beam comes out, or the sensors used to acquire targets. Once the ship has been "defanged" so to speak the aircraft could carve apart the ship at their leisure (or hoot it with a missile or something, now that the ship cannot shoot down the missile).

Originally Posted by mlangsdorf

I would also be worried, as the aircraft operator, about what happens when the beam generator misses the beam collector: the beam generator is shooting a beam that can damage an armored warship, so if it hits any part of my airframe other than the beam collector, I will probably have problems. You say it's probably a solved problem at TL10, and maybe you don't need pinpoint accuracy on the beam collector, but I worry that an airframe moving in air is something of a chaotic system and the beam generator may not be able to adequately predict the movement of the aircraft, especially when the shooting starts.

The warship mounting the laser generator would point the beam at its friendly aircraft (or, specifically, its beam collector) but not focus the beam on the aircraft. You need a tight beam focus do do much damage (other than scorching the paint level), and a defocused beam could be somewhat defended against with mirror paint and auto-darkening cockpit glass and such.

It also allows you to have a much longer range from warship to reflector aircraft. For example, suppose the warship's beam pointer has a 100 cm aperture, the aircraft has a 50 cm aperture, and you need to focus the beam to a 1 cm spot size to burn through stuff. We'll also assume the beam as a 0.0001 cm wavelength (near infrared). The range of the beam is 1.2 x (aperture size) x (spot size) / (wavelength). So directly shooting from the warship gives you a range of 1,200,000 cm = 12 km. Directly shooting from the aircraft gives you a range of 6 km. But aiming the warship's laser at the 50 cm collector lets you have a range of 600 km. Of course, the aircraft still needs to be within 6 km of the target, but you can use the aircraft to dramatically extend the effectiveness of the warship's laser to much more distant targets.

I'm glossing over some stuff here, such as how the approximate spot size still has beam spillage outside of that, so you will have some efficiency loss (or you could direct the beam into a somewhat smaller spot with the same area of collector for higher efficiency). But it gets the idea across.

You are correct that you will need a high level of coordination between the aircraft and the warship's beam guidance software.

Luke

[mlangsdorf]

Originally Posted by lwcamp

It also allows you to have a much longer range from warship to reflector aircraft. For example, suppose the warship's beam pointer has a 100 cm aperture, the aircraft has a 50 cm aperture, and you need to focus the beam to a 1 cm spot size to burn through stuff.

Beam intensity is inversely proportional to beam focus, I suspect? So the 50 cm collector is receiving 1/2500th the intensity that the eventual target will get. Or more meaningfully, a missed generator-collector shot that hits the aircraft hits at 1/2500 the intensity, which is probably not a worrisome amount.

If high efficiency nuclear reactors can't be miniaturized to reasonable aircraft, is there space for surface ships in a world of beam relay lasers? A lack of fission/fusion air-rams doesn't just invalidate hypersonic aircraft, it invalidates aircraft with loiter times measured in days, which means carrying your aircraft with you is still viable. But are aircraft viable in an environment where your aircraft can be zapped by unreasonably powerful lasers as soon as they appear on the horizon?

Submarines for water transport (assuming you need water transport) are looking more and more appealing to me, because 15-20 yards of water between your ship and the air makes a pretty good defense against relayed lasers and hypersonic missiles.

[lwcamp]

Originally Posted by mlangsdorf

Beam intensity is inversely proportional to beam focus, I suspect? So the 50 cm collector is receiving 1/2500th the intensity that the eventual target will get. Or more meaningfully, a missed generator-collector shot that hits the aircraft hits at 1/2500 the intensity, which is probably not a worrisome amount.

Inverse-square proportional. But I think you knew that, because your math uses that.

Also, that wasn't the best of examples, because with the parameters specified the aircraft laser would not reach to the horizon. So there's going to be some engineering tweaking going on here. But it gets the basic idea across.

Originally Posted by mlangsdorf

If high efficiency nuclear reactors can't be miniaturized to reasonable aircraft, is there space for surface ships in a world of beam relay lasers? A lack of fission/fusion air-rams doesn't just invalidate hypersonic aircraft, it invalidates aircraft with loiter times measured in days, which means carrying your aircraft with you is still viable. But are aircraft viable in an environment where your aircraft can be zapped by unreasonably powerful lasers as soon as they appear on the horizon?

As far as I can figure, it works both ways. The aircraft can be zapped, but so can the surface-based beam emitters. So you probably have one or more layers of screening aircraft, and when your screening aircraft can see the other guy's screening aircraft the battle starts. Eventually, one side wears away the other sides air escorts, and then you get contact between the base/ship and the attacking aircraft. This gives the base/ship one last chance for survival, but if its beam emitters get blown up before it blows up the enemy aircraft it will be left vulnerable.

This simplified analysis is neglecting other issues that might end up being important, such as electronic warfare, missiles, guided railgun projectiles, and so forth, but it gives an idea of how these things might play out.

Originally Posted by mlangsdorf

Submarines for water transport (assuming you need water transport) are looking more and more appealing to me, because 15-20 yards of water between your ship and the air makes a pretty good defense against relayed lasers and hypersonic missiles.

Again, it works both ways. That 15 to 20 meters of water means the sub cannot shoot the other guy even when it is protecting him from being shot. Once the sub surfaces, it is exposed and can be hit. This might not be a problem for hypersonic missiles - the sub pops up, gets a lock, launches its missiles, and sinks before the other guy's missiles can reach it. But for speed of light lasers the sub can be engaged as soon as it can engage.

So this leads to the issue of detection. If the sub can stealthily surface and get off a first shot, it has an advantage. The advantage is diminished if the aircraft work in swarms - the sub gets a first shot and takes out one of the aircraft, but then one of its twenty buddies takes out the sub's beam pointer (or one of them, anyway - the sub might have several just for this purpose). I have seen some analyses that with current TL8 tech a drone swarm with image recognition AI tips the stealth side of the equation away from the submarines, and the submarine can expect to be detected as it is surfacing if not before. On the other hand, these are the sorts of intellectual exercises which often prove to be very wrong when it comes to actual implementation, so I don't know how it will be at TL 10.

Luke

[RogerBW]

Originally Posted by lwcamp

Again, it works both ways. That 15 to 20 meters of water means the sub cannot shoot the other guy even when it is protecting him from being shot. Once the sub surfaces, it is exposed and can be hit. This might not be a problem for hypersonic missiles - the sub pops up, gets a lock, launches its missiles, and sinks before the other guy's missiles can reach it. But for speed of light lasers the sub can be engaged as soon as it can engage.

I read that as: the sub pops a missile, which floats up, gets a lock, and launches. It may be bobbing around on the surface while it tries for a lock, but it's a smaller and more expendable target than the whole submarine, which is heading off somewhere else.

[mlangsdorf]

Depending on how fiber optics or advanced replacements for them work, the sub might send up some tethered drones that pop up, zap a couple of planes, and get destroyed. As the drones are fairly small - a fiber optic coil, a small propeller and engine, and the beam emitter - the sub can carry a lot of them.