Space Combat

[Graham Kennedy]

Why would they have a higher thrust to weight ratio? Both ships and fighters will be using similar engine technology, unlike modern fighters and ships.

Like I said, we can only speculate. But fighters almost by definition will need to carry much smaller life support systems, food, fuel, ammo, etc etc. With less of all that to carry around it's almost inevitable that the thrust to weight ratio will be higher. I'm not suggesting that physics will dictate that fighters will always have higher acceleration, but as a practical matter it's all but inevitable.

[Captain Seafort]

Like I said, we can only speculate. But fighters almost by definition will need to carry much smaller life support systems, food, fuel, ammo, etc etc. With less of all that to carry around it's almost inevitable that the thrust to weight ratio will be higher. I'm not suggesting that physics will dictate that fighters will always have higher acceleration, but as a practical matter it's all but inevitable.

Fighters would also mount far smaller engines, meaning less thrust.

[sunnyside]

Like I said, we can only speculate. But fighters almost by definition will need to carry much smaller life support systems, food, fuel, ammo, etc etc. With less of all that to carry around it's almost inevitable that the thrust to weight ratio will be higher. I'm not suggesting that physics will dictate that fighters will always have higher acceleration, but as a practical matter it's all but inevitable.

Fighters would also mount far smaller engines, meaning less thrust.

And they have less mass, meaning more thrust to weight, meaning more acceleration. And, in space, acceleration is all you really have. You shut the engines off if you just want to go straight ahead at your current speed.

The bigger question with fighters in my mind, is why are you sending out a fighter instead of a missile? Of course the question of whether either could survive approacing ship with direct fire weapons may mean neither is especially viable.

[Captain Seafort]

And they have less mass, meaning more thrust to weight, meaning more acceleration.

No, meaning about the same thrust to mass meaning you're right back where you started.

The bigger question with fighters in my mind, is why are you sending out a fighter instead of a missile?

Exactly.

Of course the question of whether either could survive approacing ship with direct fire weapons may mean neither is especially viable.

Possibly, although that's dependent on how many missiles you send, how many PD weapons the target has, and how quickly they can switch targets.

[sunnyside]

No, meaning about the same thrust to mass meaning you're right back where you started.

I think it's fairly agreed upon that almost by definition a space fighter doesn't have to have the same level of amnities and possibly more importantly the endurance of the main ship. Of course endurance in terms of space is a little different in that you can just let inertia take you from point A to point B, but you still have to feed people, power systems and so on. Also the main ship may have done much of the work for the fighters in getting them going the right direction just by taking off and heading toward the destination, if not more elaborate launching systems.

Still, I think the bigger difference will be in how things scale. Fussion engines my simply not scale down to "fighter" sizes, leaving them with using chemical or fission based propellents. Various sorts of stealth may work on fighters but not scale up practically. etc.

Possibly, although that's dependent on how many missiles you send, how many PD weapons the target has, and how quickly they can switch targets.

I still contend that the biggest distinction is that you need not only rely on point defense. Free of the atmosphere, lasers, tiny projectiles traveling at relativistic speeds, and such could start engaging incoming missiles at great distances. This not only gives you much much more time to fire at the things, but also you need only damage them to prevent a hit, instead of point defenses where inertia will often carry the warhead into or close to the target even if you hit the sensors, guidance, or propulsion system.

What I'm saying is that in such a situation, missiles could be a lot like a bunch of natives with war clubs charging a distant gunline at the top of a steep hill. Yes, in principle you can overwhelm them. But it isn't how you'd want to design your military.


And since missiles inherantly need to course correct, I don't see how they could have the stealth properties to prevent detection unless their emissions are hidden by celestial phenomina behind or in front of them.

[Coalition]

I think it's fairly agreed upon that almost by definition a space fighter doesn't have to have the same level of amnities and possibly more importantly the endurance of the main ship. Of course endurance in terms of space is a little different in that you can just let inertia take you from point A to point B, but you still have to feed people, power systems and so on. Also the main ship may have done much of the work for the fighters in getting them going the right direction just by taking off and heading toward the destination, if not more elaborate launching systems.

Scaling is an important detail, as smaller engines might be more efficient engines. The max power of a reactor will be limited to what the reactor walls can handle. So if you build an engine twice as wide, tall, and long, it will mass twice as much, but only have four times the surface area. This means the engine will only put out four times the power. This allows smaller reactors to run with more power per unit mass.

Of course the fun part is when you get into the various halving weights of radiation shielding, so you could double the output of a reactor, but only increase the radiation shielding by 10%. This gives an advantage to larger reactors.

For life support, you have a linear scale for food up to 5 months, then after that you use gengineered algae for your food. 5 months is pretty much the break point where the life support for the algae and recycling system is equal in mass to stored food. I don't know what the break point for life support is for recylcing vs compressed O₂ and/or oxygen candles.

Still, I think the bigger difference will be in how things scale. Fussion engines my simply not scale down to "fighter" sizes, leaving them with using chemical or fission based propellents. Various sorts of stealth may work on fighters but not scale up practically. etc.

If all you have is chemical thrusters for your smaller vessels, then they are going to be effectively useless against a nuclear engined opponent. The mass fraction needed for fuel will mean the warhead will be very small relative to the overall missile. A 1st generation Orion drive from 1959 is eight times stronger than the theoretical max for chemical rocketry. The 2nd Generation Orion is three time stronger than the 1st Generation. Here is a sample engine list.

I still contend that the biggest distinction is that you need not only rely on point defense. Free of the atmosphere, lasers, tiny projectiles traveling at relativistic speeds, and such could start engaging incoming missiles at great distances. This not only gives you much much more time to fire at the things, but also you need only damage them to prevent a hit, instead of point defenses where inertia will often carry the warhead into or close to the target even if you hit the sensors, guidance, or propulsion system.

Ah, the Purple/Green debate.

And since missiles inherantly need to course correct, I don't see how they could have the stealth properties to prevent detection unless their emissions are hidden by celestial phenomina behind or in front of them.

There is no stealth in space. They will know you are coming for weeks or months beforehand.


This is a fun thread, let's keep going.

[sunnyside]

There is no stealth in space. They will know you are coming for weeks or months beforehand.


This is a fun thread, let's keep going.

Hmmm. I'm not entirely sure about that.

There are three sources of detection. The ship itself, the propellant trail, and active sensors or which radar is all that is coming to mind at the moment for long range.

The propellant trail seems unmanageable. However your site lists fission engines accelerating hydrogen. The trail normally would emit photons which could be detected. However if you, say, stripped off elections and alternated firing protons and electrons, I think the particles may just leave as fairly nice simple waves, and not have an excited state to come down from. Thus the emission trail is invisible. And in any case you don't have to keep burning as you travel, you could even use a stage to get the ship going with an engine for deceleration and than go quite. Or have a mix where a high energy engine gets the ship going, and the stealthy but lower energy and possibly inefficient engine provides for some stealthy jinks

For the ship you could simply have something like a large disk in front. It's a reflector on the ships side, and to the other side it is a simple black body radiator of the appropriate temperature. Or something even more elaborate. Obviously this works best if you know the direction your enemy is looking from, but that might not be so unreasonable.

As for active sensors. Radar reflective/absorbing materials can be of great use. Sufficiently low frequency radar can be a problem, but I'm given to understand the dipole like response of the target makes active cancellation easier. And in any case the great distances and problems with managing low frequency radar may make it not so useful anyway.

And in any case with active sensors you have the submarine problem of the target having a better idea of where you are than you do of where they are, and they'll know it a little earlier too, putting you at a tactical disadvantage.

So if I'm right about those things, stealth could pan out as an option.


One other thing. There was all that talk about having to dump heat energy with lasers. However if a given hard science ship has a signficant percentage of it's mass taken up by propellent, is there any reason why the heat couldn't be dumped into a pre-heater for the hydrogen? Or, if you have propellant to lose, allow it to be used for evaporative cooling?

[Tyyr]

The propellant trail seems unmanageable. However your site lists fission engines accelerating hydrogen. The trail normally would emit photons which could be detected.

Actually its not light, its the thermal signature that will be the dead give away.

However if you, say, stripped off elections and alternated firing protons and electrons, I think the particles may just leave as fairly nice simple waves, and not have an excited state to come down from. Thus the emission trail is invisible.

Again, it's the thermal properties of the trail, the fact that it's hotter than the surrounding space, that'll give it away. I'm not even sure you could actually make an engine that used both protons and electrons. With the volume you'd need to move a combat ship around at any appreciable acceleration you'd have some interesting goings on in your exhaust stream.

And in any case you don't have to keep burning as you travel, you could even use a stage to get the ship going with an engine for deceleration and than go quite. Or have a mix where a high energy engine gets the ship going, and the stealthy but lower energy and possibly inefficient engine provides for some stealthy jinks

Except that there is no stealthy engine and secondly your opponent would be able to track the first stage engine to know you're coming.

For the ship you could simply have something like a large disk in front. It's a reflector on the ships side, and to the other side it is a simple black body radiator of the appropriate temperature. Or something even more elaborate. Obviously this works best if you know the direction your enemy is looking from, but that might not be so unreasonable.

Unless your opponent doesn't just have sensors in one location but in several which would be a very logical thing to do. It also doesn't help when you have to swing around and decelerated lest you overshoot your target.

One other thing. There was all that talk about having to dump heat energy with lasers. However if a given hard science ship has a signficant percentage of it's mass taken up by propellent, is there any reason why the heat couldn't be dumped into a pre-heater for the hydrogen? Or, if you have propellant to lose, allow it to be used for evaporative cooling?

Well, if you're worried about detection the last thing you want to do is make your exhaust trail hotter or put more hot material out of the space craft where it can be detected. As for dumping heat with lasers, I'm pretty sure thermodynamics says that's impossible, especially since lasers aren't more than 100% efficient at converting energy into a beam.

[sunnyside]

Actually its not light, its the thermal signature that will be the dead give away.

The thermal signature IS light, and it's what I was talking about.

Again, it's the thermal properties of the trail, the fact that it's hotter than the surrounding space, that'll give it away.

That would be true of whole atoms or molecules. But the "thermal properties" you are referring to relates to the release of photons due to excited energy states between the subatomic particles in the atom, molecule, or groups of either.

However for a single isolated subatomic particle, I don't think it releases those photons. In fact the concept of "temperature" as opposed to velocity gets awfully fuzzy in such cases.

I'm not even sure you could actually make an engine that used both protons and electrons. With the volume you'd need to move a combat ship around at any appreciable acceleration you'd have some interesting goings on in your exhaust stream.

To be clear engines that could do it exist today. You'd just have to have some tweak on an ion thruster. Now how well you can scale that up is a different question. Thoretically it wouldn't be a problem, but practically it might.

Still one should be able to produce small amounts of thrust this way. So long as this is a slow manuvering engine instead of the 'main' engine you're fine.

your opponent would be able to track the first stage engine to know you're coming.

That's true only if they can see and resolve the launch , but that again comes to the issue of the second stealthy engine. They may know you're coming. But they wouldn't know exactly where you are.

Unless your opponent doesn't just have sensors in one location but in several which would be a very logical thing to do. It also doesn't help when you have to swing around and decelerated lest you overshoot your target.

Well you would have to swing around to some degree. If a stealth capability is important and you're in war, priority should go to targeting the sensors that are behind your ship.

Well, if you're worried about detection the last thing you want to do is make your exhaust trail hotter or put more hot material out of the space craft where it can be detected. As for dumping heat with lasers, I'm pretty sure thermodynamics says that's impossible, especially since lasers aren't more than 100% efficient at converting energy into a beam.

Well, the stealth thing is a seperate discussion. Though you could parhapse gett close stealthly and than throw stealth aside as you open up.

As forthe rest I mean dumping heat from a laser to the propellent. I.e. excell heathas

[Tyyr]

The thermal signature IS light, and it's what I was talking about.

It's electromagnetic radiation of various wavelengths. You don't typically refer to thermal radiation as photons.

However for a single isolated subatomic particle, I don't think it releases those photons. In fact the concept of "temperature" as opposed to velocity gets awfully fuzzy in such cases.

I'm fairly certain that it does. First you can't get such an exhaust stream as discrete protons and electrons, you start expelling them in sufficient quantities to accelerate a large space ship in a militarily useful time frame and they will recombine into an ionized gas at the very least. On top of this photons are emitted from other events that don't involve energy level transitions in atoms. Hell, synchrotron radiation can be emitted from electrons moving through strong magnetic fields, aka ion engines.

To be clear engines that could do it exist today. You'd just have to have some tweak on an ion thruster. Now how well you can scale that up is a different question. Thoretically it wouldn't be a problem, but practically it might.

That's my point. I know about ion thrusters. However they tend to function with only one charge. They don't flip back and forth between emitting positively and negatively charged particles. It'd take some more research but you'd likely wind up with a pulse engine that would emit one charge, wait, then emit another just to avoid constantly pulling your own exhaust back and canceling any thrust.

That's true only if they can see and resolve the launch , but that again comes to the issue of the second stealthy engine. They may know you're coming. But they wouldn't know exactly where you are.

Any kind of direct approach though will unlikely be hidden though. You can work out orbits quite easily that allow you to hide your launch and use close approaches to planets to alter your course to where you want to go but then you're talking months or even years to get where you're going. That's fine for probes but I doubt the military will want to send its ships out on multi-year trips like that in the middle of a shooting war.

Well you would have to swing around to some degree. If a stealth capability is important and you're in war, priority should go to targeting the sensors that are behind your ship.

They don't even have to be behind. They can be to the side and again, since you're going to have to decelerate at some point you're going to point your engines right at your target or pretty damn close to it. You can shoot down every sensor your opponent has, especially since if they're most will be passive and set up in such places as to avoid easy detection.

Well, the stealth thing is a seperate discussion. Though you could parhapse gett close stealthly and than throw stealth aside as you open up.

Obviously that's an option and you'd really have to eventually anyways but I just doubt you could approach stealthily to begin with.

As forthe rest I mean dumping heat from a laser to the propellent. I.e. excell heathas

Yes, you can use propellant as a heat sink. The problem is that lasers are typically inefficient at converting power to a laser beam. For every three watts in you get one watt of laser out. Those other two watts become heat. You're going to very quickly heat your propellant up using it as a heat sink. If you're using something that can convert to a gas at a lower temperature then you're in real trouble as your propellant tanks will have to be designed to be far stronger than if you just used them to store a slush like material.

[sunnyside]

You don't typically refer to thermal radiation as photons.

I don't know about that. In any case, that's what it is made up of and we understand each other now in any case.

I'm fairly certain that it does. First you can't get such an exhaust stream as discrete protons and electrons, you start expelling them in sufficient quantities to accelerate a large space ship in a militarily useful time frame and they will recombine into an ionized gas at the very least. On top of this photons are emitted from other events that don't involve energy level transitions in atoms. Hell, synchrotron radiation can be emitted from electrons moving through strong magnetic fields, aka ion engines.

Obviously you don't release them at the same time. As electrons are generally easier to store I'd say you start with accelerated hydrogen, strip the electrons, eject protons for a bit. Than stop and eject the stored elections. Than start stripping more hydrogen.

Obviously this requires more equipment and slows the process however a militarily useful time may be months for hard science space travel. By the time you're trying to jink out of the way of missiles or gauss rounds the jig is up. And you're probalby kidding yourself in any case.

Sychrotron radiation wouldn't be a factor for the exhaust except in very rare and specific instances. The point is you need some sort of interaction to produce the energy different required for photon creation, and in the simple case of a lone proton, I don't think there is any interaction involved.

That's my point. I know about ion thrusters. However they tend to function with only one charge. They don't flip back and forth between emitting positively and negatively charged particles. It'd take some more research but you'd likely wind up with a pulse engine that would emit one charge, wait, then emit another just to avoid constantly pulling your own exhaust back and canceling any thrust.

Actually existing ion thrusters just dump the electrons back into the positive ion stream, because it's simply and they have no reason not to. Actually, if constant thrust is your thing, you could simply route the low massed electrons into some electron guns that fire them off in different directions to the proton stream. That would add very little weight to an ion thruster and cause very little reduction in thrust.

Any kind of direct approach though will unlikely be hidden though. You can work out orbits quite easily that allow you to hide your launch and use close approaches to planets to alter your course to where you want to go but then you're talking months or even years to get where you're going. That's fine for probes but I doubt the military will want to send its ships out on multi-year trips like that in the middle of a shooting war.

It's basically the same route as any other craft would take. You just apply a little lateral motion to put yourself a few hundred kilometers off the beaten path.

They don't even have to be behind. They can be to the side and again, since you're going to have to decelerate at some point you're going to point your engines right at your target or pretty damn close to it. You can shoot down every sensor your opponent has, especially since if they're most will be passive and set up in such places as to avoid easy detection.

Presumably you'd have utilized your weapons systems prior to major deceleration. And "places as to avoid easy detection" are the sort of "brown waters" where you'd probably already be able to fire on a primary target, or be screwed by a weapon system hiding in the same place. In any case it really is an entirely different situation compared to deep space combat.

Yes, you can use propellant as a heat sink. The problem is that lasers are typically inefficient at converting power to a laser beam. For every three watts in you get one watt of laser out. Those other two watts become heat. You're going to very quickly heat your propellant up using it as a heat sink. If you're using something that can convert to a gas at a lower temperature then you're in real trouble as your propellant tanks will have to be designed to be far stronger than if you just used them to store a slush like material.

I suppose you could run the math. But we're talking about a heat sink that makes up most of the mass of the vessel. With a preheater to the accelerator you are litterally dumping the excess energy out the back of the ship while still getting full thrust out of the propellant. And you do retain the option to just vent superheated propellant steam out the thrusters to dump even faster if you have to.

[Coalition]

It's basically the same route as any other craft would take. You just apply a little lateral motion to put yourself a few hundred kilometers off the beaten path.

A few hundred kilometers is not enough. A human being in a space suit can be detected by current technology at ~1 light-second, aka ~300,000 km. Current technology on a dedicated satellite would be able to do a sky sweep for hot spots in ~4 hours.

Presumably you'd have utilized your weapons systems prior to major deceleration. And "places as to avoid easy detection" are the sort of "brown waters" where you'd probably already be able to fire on a primary target, or be screwed by a weapon system hiding in the same place. In any case it really is an entirely different situation compared to deep space combat.

So you are going to remove the sensors that are on your approach path? Sounds like you might have the defenders asking themselves this:
http://www.schlockmercenary.com/d/20010525.html

Seriously, if you are destroying the sensors on the way to your target, then they are going to know you are hostile. Without sensors, they will likely tell a ship in orbit to take a look before they decide how large the reception needs to be.

Here is the stuff for stealth in space (even a ship with engines off will be detected easily):
http://www.projectrho.com/rocket/rocket ... #nostealth

Here is why decoys won't work (short version, their engines won't match the acceleration used for the ship):
http://www.rocketpunk-manifesto.com/200 ... dered.html

Here is a set up for why coolant lasers wouldn't work (short verson, you are breaking even):
http://www.projectrho.com/rocket/rocket ... #radiators

[sunnyside]

A few hundred kilometers is not enough. A human being in a space suit can be detected by current technology at ~1 light-second, aka ~300,000 km. Current technology on a dedicated satellite would be able to do a sky sweep for hot spots in ~4 hours.

Obviously don't bother if you aren't doing the stealth thing.

Seriously, if you are destroying the sensors on the way to your target, then they are going to know you are hostile. Without sensors, they will likely tell a ship in orbit to take a look before they decide how large the reception needs to be.

Here is the stuff for stealth in space (even a ship with engines off will be detected easily):
http://www.projectrho.com/rocket/rocket ... #nostealth

Here is why decoys won't work (short version, their engines won't match the acceleration used for the ship):
http://www.rocketpunk-manifesto.com/200 ... dered.html

Here is a set up for why coolant lasers wouldn't work (short verson, you are breaking even):
http://www.projectrho.com/rocket/rocket ... #radiators

Alright. The fundamental issue here is that you (and they) can't get off the requirement that stealth has to be something like a Romulan cloack where you're invisible to all aspects at all times. Well, as noted, that won't work.

But being stealthy to a cone of space? I see no reason why that wouldn't be fairly easy to do.

However as noted, if there is a sufficiantly vast sea of sensors systems on the way in than the ship(s) in front are just going to have to blaze a trail. You might not even bother with having the front ships be stealthy at all. Maybe just equiped with very long range but otherwise unimpressive sensor busting weapons.

It's the wave afterwards that's a threat. (well, aside from the cost of the large number of sensors.)


I'm also curious where the comments on coolant lasers come from. I was talking about dumping the heat into the propellant.


Another bizzare thing about the sight you reference is their belief that radiators aren't an option because they are "vulnerable and will be shot off". Now, I'm not arguing that radiators would be vulnerable. However the very premis of that argument is that, in contrast to the radiators, the rest of the ship is soaking up hit after hit.

If you have armor technology where you can slam a dozen missiles into the thing and it keeps coming that you're verring into battleship territory as armoring up is obviously effective vs the missiles.

If, however, a missile will kill the ship, than it really doesn't matter if your radiators are out or not now does it?

[Coalition]

Obviously don't bother if you aren't doing the stealth thing.

Lost parts watch, Dutchman duties, and general search routine. Lost parts will still have a faint heat signature, so you don't have to worry about a lost screwdriver going through someone's forward hull. Dutchman watch in case someone stepped outside and got loose, and their coms aren't working. General search is along the same lines of why airports have radar on even when there are no known planes around.

A heat watch satellite is a simple set of sensors, a computer, and a program. Given that there is extensive orbital infrastructure in place, launching one of these would be a high school project from an orbital school.

Alright. The fundamental issue here is that you (and they) can't get off the requirement that stealth has to be something like a Romulan cloack where you're invisible to all aspects at all times. Well, as noted, that won't work.

But being stealthy to a cone of space? I see no reason why that wouldn't be fairly easy to do.

However as noted, if there is a sufficiantly vast sea of sensors systems on the way in than the ship(s) in front are just going to have to blaze a trail. You might not even bother with having the front ships be stealthy at all. Maybe just equiped with very long range but otherwise unimpressive sensor busting weapons.

It's the wave afterwards that's a threat. (well, aside from the cost of the large number of sensors.)

The shuttle's main engines can be detected past Pluto. Its maneuvering engines can be sen from the asteroid belt. Does that tell you what sort of range you need for your anti-sensor weaponry? Also, given that the locals have a high level of orbital technology, replacing those sensors will be a minor project. Those new sensors will likely get tossed out at right angles to your path, so you have to chase them down if you want to hide your main force.

Your entire fleet is going to be seen, unless they start so far out that they will need multi-year missions to succeed. The defenders can use a sensor of some kind (optical, thermal, or other EM) to measure how bright the total exhaust is. A pair of sensors in orbit (or the same sensor, on the other side of its orbit) provide parallax and a baseline to get range. Doppler shift of your exhaust tells me how fast it is heading towards or away from me. Brightness, range, and Doppler shift gives me the total mass of your force, along with using a telescope to measure their acceleration.

Measured thrust divided by observed acceleration gives estimated mass. Once I know the total mass of your force, I can decide if you are a threat or not. If you thrust the entire trip, that estimate will go down as your ships willbe burning up fuel mass along the way. Examination of the exhaust will provide me with the type of engine you use also.

If you try to hide it with one force decelerating brightly, and the second force farther behind, I will notice that the graph of your brightness is not matching the plotted graph based on the forward force.

Even more fun is that as soon as you get close enough, I'll see you even without your engines on.

As to the cost of the sensors, most stuff today in orbit paid a heft price due to having to launch it out of a gravity well. Orbital infrastructure (plus nuclear engines) would bring launch costs down. Bringing a nickel-iron asteroid from the Trojans or the asteroid Belt would solve a lot of the material needs of an orbital civilization.

Another bizzare thing about the sight you reference is their belief that radiators aren't an option because they are "vulnerable and will be shot off". Now, I'm not arguing that radiators would be vulnerable. However the very premis of that argument is that, in contrast to the radiators, the rest of the ship is soaking up hit after hit.

If you have armor technology where you can slam a dozen missiles into the thing and it keeps coming that you're verring into battleship territory as armoring up is obviously effective vs the missiles.

If, however, a missile will kill the ship, than it really doesn't matter if your radiators are out or not now does it?

I'm not sure what you are asking here. Are you asking if radiators are useful? The answer is yes. They provide cooling capacity so that the ship doesn't melt. Are they tactically a problem? Also yes, as you either need to hold down the acceleration to what they can stand (limiting your maneuvering, and making the enemy's job easier), or you make the radiators tougher, using mass that could be used for more missiles instead.

[sunnyside]

Alright, I think maybe there have been too many points of discussion, as ignoring one part is used to justify why others wouldn't work.

part one is that, while low on immediate thrust, an engine that gets it's thrust from a proton steam will, I think, produce a trail that does not emit a thermal signature, nor would it be detectable to telescopes or radar because of the inability of a single proton to absorb a photon.

part two is that while all aspect stealth is impossible, a large dish in front of a ship, one side a reflector and the other creating the image of a black body radiator at the appropriate temperature (or something more sophisticated). This frontal dish would also likely have requirments vs more active sensors. The sides of the ship could also have reflector/black body radiator sets making them hard to see via thermal detectors. The reason why all this doesn't break a law of thermodynamics is that all this reflected light is allowed to freely radiate out the rear of the craft. Making them quite visible to that direction.

Part three is that whatever the cost of the sea of sensors, the requirement that they have to detect the sides of something from part 1 and that they communicate with the home planet means that at the least they should be more expensive than the cost of the coil gun slug that takes them out. Since the fleets would be in battle already if they were in range and the sensors velocity woud likely be constant, shooting at them is simple and convenient.

Feel free to debate these. However it is not a valid line of reasoning to say something like " I don't agree with part 1 and so part 2 wouldn't work. Now that we've established that part 2 doesn't work, it's clear that even if it worked part 1 is meaningless. So the system doesn't work". If you wish to attack something, go after it on it's own merits.

I'm not sure what you are asking here. Are you asking if radiators are useful? The answer is yes. They provide cooling capacity so that the ship doesn't melt. Are they tactically a problem? Also yes, as you either need to hold down the acceleration to what they can stand (limiting your maneuvering, and making the enemy's job easier), or you make the radiators tougher, using mass that could be used for more missiles instead.

As I understand it, the website you directed us to during the earlier radiator discussion is of the opinion that a near deal breaking problem for laser based weapons is that most types of radiators cannot be armored and thus will be "shot off" in battle.

My point was that, especially in regards to missile based opponents, this seems to presume that the rest of the ship can soak up impacts. If the ship cannot, the relative vulnerability of the radiators is a relative non issue.

They had not brought up accleration. However without atmosphere to push against it's simply a matter of the radiator being able to handle the stresses from its own probalby fairly low inertia. This may well create some practical limits even if you use tension cables. Though there are also limits to how fast the ship itself can turn or accelerate due to its own structural intergrity and engine capability.