Whay would real-life war spacecraft look like?

[1greywind]

It's absolutely stupid.

Suppose you have large country (realy large, so large that you can't afford to build more than one railroad line crossing it in east-west direction). And you need to protect it from short time global nuclear strike. How many options do you have? Build thousands silos for 30-miter sized missiles? Dedicate multipli million-square-kilometers regions to host road-mobile ISBM's? Put armed ISBM's on rails and move them around on civil railroad network? Considering all that USSR have done to protect itself, military station on orbit is practical and sane.

[megatiger78]

Like this..

http://img2.wikia.nocookie.net/__cb20131108160442/starwars/images/7/72/DeathStar1-SWE.png

A Dyson sphere surrounding a white dwarf would have enough energy to move itself and burn entire worlds...

yes 10char

[Nibb31]

Suppose you have large country (realy large, so large that you can't afford to build more than one railroad line crossing it in east-west direction). And you need to protect it from short time global nuclear strike. How many options do you have? Build thousands silos for 30-miter sized missiles? Dedicate multipli million-square-kilometers regions to host road-mobile ISBM's? Put armed ISBM's on rails and move them around on civil railroad network? Considering all that USSR have done to protect itself, military station on orbit is practical and sane.

The idea is so idiotic, I don't know where to start.

- Building thousands of silos and SSBNs is cheaper, safer, and more redundant than building a single orbital space station.

- What's the advantage of a wingless space shuttle when you have purpose built FGB or DOS spacecraft?

- Why wingless?

- Why would you want to put nukes inside BOR spaceplanes that are easy to intercept and provide ample time to retaliate when you have fast re-entry MIRVs?

- Why launch the nukes from space shuttles when you can launch them from the station?

- Why build a massive highly-vulnerable multi-core space station when you can have lots of smaller redundant ones?

- Why build a space station at all when all you need is to put the MIRVs on orbit with a retromotor to deorbit them when needed?

- How does this give you a faster response time than suborbital ICBMs launched from a fleet of SSBNs?

[1greywind]

@Nibb31? Have you actually read the text on link?

1

Building thousands of silos and SSBNs is cheaper, safer, and more redundant

It isn't. Mostly because in space you don't need to protect your silos from cruise missiles strikes.

2

Combat modules are based on Buran becouse Buran's superrior propolution unit (>2000 m/s of dV), robotic arm and cargo-bay are much more suitable as platform for space-based nuclear platform than small DOS or FGB bodies. DOS based laser (áúøф) and missile (ÚðÑÂúðô) payloads were included in system and are delivered into orbit by Buran orbiter.

3

Becouse you don't need wings then you don't have stupid "launch into polar orbit and land at same base" condition on mission list.

4

Because this gives hypersonic maneuverability, lower angle of attack and higher precision comparing to free-falling reentry vehicle.

5

Becouse area of total destruction on enemy territory should be wider, then single station orbital track projection. Also station is place for weapon and combat modules maintenance by kosmonauts.

6

Becouse many-to-one is generaly cheaper then many-to-many architecture becouse you can distribute duplicated functions (diagnostics, maintenance, refueling, etc) between combat moudles and station.

7

Becouse it is easy to pretend that you perform "asymmetric protection measures" in face of other countryies if you have all weapons on single orbit under kosmonauts eye.

8

It is not matter of faster response time. It is matter of more first strike proof nuclear retalation platform. Soviet nuclear war doctrine was build around "uncounterable retaliation" in face of american "disarming first strike".

[Nibb31]

Building thousands of silos and SSBNs is cheaper, safer, and more redundant

It isn't. Mostly because in space you don't need to protect your silos from cruise missiles strikes.

It is. Proof is, the USSR actually built thousands of silos, but only built one space station and only could only fund a single Buran flight.

Silos only cost concrete and manpower. Those were cheap commodities in the Soviet Union.

Combat modules are based on Buran becouse Buran's superrior propolution unit (>2000 m/s of dV), robotic arm and cargo-bay are much more suitable as platform for space-based nuclear platform than small DOS or FGB bodies. DOS based laser (áúøф) and missile (ÚðÑÂúðô) payloads were included in system and are delivered into orbit by Buran orbiter.

Why would it need so much delta-v? Even if you did, you are better off designing a specialized spacecraft around the propulsion system than to adapt an existing design into something it wasn't designed for in the first place. Or just stick Buran's engines on an FGB shell.

Becouse you don't need wings then you don't have stupid "launch into polar orbit and land at same base" condition on mission list.

Then why use a Buran in the first place? You don't need the robotic arm, cargo bay doors, fuselage, cockpit, landing gear, TPS... All those things are useless weight on a spacecraft that is designed to stay in space. They serve no purpose. Why spend so much effort modifying Buran when it would be easier to design a dedicated spacecraft from scratch?

Because this gives hypersonic maneuverability, lower angle of attack and higher precision comparing to free-falling reentry vehicle.

No it doesn't. There is no hypersonic maneuvrability. It comes down in a straight line on a highly predictable trajectory and much slower (and easier to detect and shoot down) than a traditional MIRV. It's also heavier and more expensive, which means fewer warheads and a much smaller total yield.

Becouse area of total destruction on enemy territory should be wider, then single station orbital track projection. Also station is place for weapon and combat modules maintenance by kosmonauts.

Why would the area of destruction be wider than a conventional ICBM attack? You could just launch the MIRVs and re-entry vehicles in different directions at different times with their own guidance and propulsion system. You can reach any point from orbit. There is no need for the "BOR launcher Burans".

Becouse many-to-one is generaly cheaper then many-to-many architecture becouse you can distribute duplicated functions (diagnostics, maintenance, refueling, etc) between combat moudles and station.

That's wrong. A single shot could disable your only space station. And you can just design your system so that it doesn't need maintenance and refueling. The Soviet Union was perfectly capable of building unmanned spacecraft and reentry vehicles.

Becouse it is easy to pretend that you perform "asymmetric protection measures" in face of other countryies if you have all weapons on single orbit under kosmonauts eye.

No it isn't. A space station like this is ridiculously vulnerable. There are dozens of ways the enemy could disable it. A "Starfish Prime" explosion 50km below it would fry its electronics and kill everyone on board. And there is no way you could stop such an attack. A salvo of ASAT missiles would kill it too.

And then there's the risk of something going wrong on the station. Mir had dozens of faults and malfunctions. If it had been a military station, it would only have been operational 50% of the time, at best. If you have only one of these battle stations, you have no redundancy. You would be better off with multiple Salyut-type stations.

It is not matter of faster response time. It is matter of more first strike proof nuclear retalation platform. Soviet nuclear war doctrine was build around "uncounterable retaliation" in face of american "disarming first strike".

How is it "first-strike-proof"? It would be under constant observation and the first target to be destroyed.

[Frozen_Heart]

It is. Proof is, the USSR actually built thousands of silos, but only built one space station and only could only fund a single Buran flight.

While I do agree that the silos would be cheaper and more effective, saying that an organisation with 50 times the budget of ROSCOSMOS can do more than them as evidence isn't great logic.

If you had swapped the budget of the Russian military with that of their space agency then they could have built much more than one station.

[Tex_NL]

...

No it isn't. A space station like this is ridiculously vulnerable. There are dozens of ways the enemy could disable it.

...

Why not simple create a shrapnel cloud in a retrograde orbit at the proper altitude. Unless you have some kind of scifi shielding it would be nearly impossible to avoid being hit by thousands of shrapnel pieces travelling at a relative velocity of over 50.000 kph.

[RainDreamer]

Why not simple create a shrapnel cloud in a retrograde orbit at the proper altitude. Unless you have some kind of scifi shielding it would be nearly impossible to avoid being hit by thousands of shrapnel pieces travelling at a relative velocity of over 50.000 kph.

Because we can't control it and may very well be hit by the same thing?

[1greywind]

"Those were cheap commodities in the Soviet Union", "There is no hypersonic maneuvrability", "just stick Buran's engines on an FGB shell", "A salvo of ASAT missiles".

Oh, I see.

[Nibb31]

While I do agree that the silos would be cheaper and more effective, saying that an organisation with 50 times the budget of ROSCOSMOS can do more than them as evidence isn't great logic.

If you had swapped the budget of the Russian military with that of their space agency then they could have built much more than one station.

The problem is that by the time the Soviet Union was flying Buran and Mir, they already had those thousands of silos, mobile launchers, long-range bombers, and SSBNs. There was never any purpose for a manned orbital nuclear launch platform, because it has no strategic benefit over the other cheaper and more reliable delivery methods. Both the Americans and the Russians knew that.

Edited November 29, 2014 by Nibb31

[EzinX]

If the principal weapons are frequently firing direct-fire weapons, such as guns or lasers, ships should be cheap and small. Lanchester's square law applies in such combat: an n-fold advantage in quantity is equivalent to an n²-fold advantage in quality, with 'quality' meaning the rate at which a ship can destroy or disable enemy firepower.

I'm rather curious as to what this means for the age-old weapons vs armor/defensive weapons tradeoff. Or, http://en.wikipedia.org/wiki/Salvo_combat_model

You have a choice with your space battlewagon. Say you have a fixed amount of payload capacity (everything else is fuel/engines/heat radiators/etc). Do you install 1 long range weapon and use the remaining mass for armor, or do you fit as many long range weapons as you have payload for?

Let's flesh out a theoretical space battle a bit more.

First of all, scaling laws apply to warship weapons and engines.

Weapons :

A 5 meter laser mirror has twice the range of a 2.5 meter laser mirror. (it can create a spot of given area at double the distance)

A railgun that launches projectiles of a fixed mass at 10 kilometers/second has 4 times the mass of a railgun that launches them at 5 kilometers/second.

Enemy antimissile defenses mean that there is a minimum "volley size" before you do more than 0 damage using missiles to another warship.

Engines :

Orion drives are more efficient using bigger nukes, also the pusher plate has a minimum mass and a minimum thickness to work at all.

Nuclear salt water engines have a minimum size, or there won't be enough fuel in the reaction chamber for a critical mass

Nuclear-electric engines need a nuclear reactor, which is also more efficient if it is larger and has a minimum size.

So, there's a minimum size for a space warship for it to be an effective combatant, and it's probably pretty large in order to fit those 5-10 meter + laser mounts, etc.

Why not "go big or go home" and put all your resources into a single gigantic space warship?

Too big, and you get diminishing returns from longer range laser beams because at a certain distance the speed of light lag means you won't be able to hit an enemy ship that is random walking.

Also, no matter how big a space warship is, a single direct hit (warhead punches through the hull detonating inside) from a nuclear bomb will destroy it. (unless it's ludicrously large, but that's another discussion)

So there's probably an optimal size in the middle.

How might a battle go?

2 space warships, equal mass, equal technology, they are fighting over empty space for the Lulz.

At extreme ranges (interplanetary distances), one warship could simply fire a volley of nuclear missiles (robot spacecraft set to ram) and head home. It's all or nothing - either the defending warship has enough anti-missile guns to shoot down the entire volley or it gets blown up.

Assume both warships determine the other has too much point defense and they save their missiles.

Tens of thousands of kilometers : both warships are beginning to get spot sizes with lasers that are small enough to at least not waste most of the laser energy to space.

This is where armoring is important : you could make the part of the spacecraft hull that faces the enemy have a layer of liquid sodium heat pipes to carry the heat from the enemy laser weapon to your radiators. Until the beam intensity is high enough to just start sublimating your hull to gas, lasers would be ineffective.

This is also where an interesting tradeoff emerges. A laser mirror for a high intensity beam has to be a http://en.wikipedia.org/wiki/Dielectric_mirror or it will not be reflective enough. Apparently, 5 megawatts/square centimeter is achievable. However, the dielectric mirror only works for a narrow frequency range, and the coating itself has a thickness equal to the wavelength of the light used. (so just 475 nanometers for blue light).

So if your warship uses a different frequency for your lasers than the enemy, you could aim your laser weapons right at their mirror, burn just a few atoms of that delicate dielectric coating, and their mirror would now be junk and they would have to stop firing or burn up their own mirror.

But then again, both warships could hide their mirrors behind armored shutters and essentially play a game of chess where one warship exposes a mirror, the other counters by firing on that mirror, the other counters the counter by firing on THAT mirror and so on.

Once the 2 warships are done playing "the blinding game", and presumably one warship is out of mirrors but the other has a few left, they can move a bit closer and open fire on each other with railguns/coilguns.

Kinetic cannon shots will have to contain miniaturized rocket engines and guidance systems because this battle is still happening at ranges of thousands of kilometers. If both ships have orion or nuclear salt drives, each one will try to outrun incoming fire from the other, and orion drives and nuclear salt water engines are more efficient than the tiny chemical thrusters you could fit into a kinetic cannon shot. So there is a maximum range at which the kinetic cannon shot has expended it's delta V and can no longer chase after the target warship.

Both ships could also defend against incoming fire using defensive railgun/coilguns or even chemical guns to shoot down incoming kinetic rounds. This is another case where armoring matters : it would not be practical to build armor to stop an incoming slug traveling at 10 km/second or more, but you could have armor using whipple shields to block hypervelocity shrapnel from destroyed incoming rounds or fragmentation rounds that blow up before they hit your ship.

At this range, the warship who has remaining laser mirrors will have an advantage because it can either use the lasers to shoot down incoming kinetic rounds or use it to burn holes in the enemy ship to disable important systems. A science fiction, but plausible, technology that would somewhat counter this would be a nanotechnology repair system that could resurface a laser mirror in a few minutes so that the ship that lost mirrors could repair the minor damage to their surfaces and resume firing.

The shooting continues until either one warship or another surrenders, or the winning warship kills the radiators or nuclear reactors powering the loser (which stops the losing warship from being able to continue firing weapons like railguns/coilguns/lasers because he no longer has the enormous electrical power supply needed). Once the loser cannot shoot back, the winner could careful snipe all the anti-missile defenses on the losing warship and finish it off with a single nuclear warhead tipped missile. Note that radiators can be protected if they are liquid droplet radiators because you can armor the booms and even have spare booms to extend when the main ones are destroyed (since the booms are relatively small and light compared to the mass of the ship)

Honestly, this doesn't sound boring. There's quite a lot of interacting systems, and different design philosophies in the opposing warships could greatly change the outcome of the battle. It might make for a decent space simulator game, even...

[jwenting]

If by "combat spacecraft" you're thinking of Star Wars or Buck Rogers style warfare, it simply won't work.

Ditto Star Trek.

What can work is ships designed for orbital bombardment of planets, ships designed to change the orbits of asteroids and other rocks to crash onto planets, and those planets employing energy weapons or interceptor rockets (SAMs...) to engage those.

[khyron42]

Regarding armed space stations - the military of both the USSR and US were originally very interested in the Moon. There were plans under way well before Apollo for moon missile bases. The reason? The same as any cold war project - Mutually Assured Destruction.

The thinking among army and air force was, I'll put my missiles where the other guy can't attack them without giving lots of advance warning. My missiles also are so far away that they can't be used as a first strike weapon any more, but they're a guaranteed retaliatory strike. Now the other guy will never attack, because he knows he'd die too.

In the meantime, the navy came up with the ballistic missile submarines, which gave the same retaliatory strike benefit without the 3-day flight time, were much cheaper overall, and also could be used for a possible first-strike weapon. And all of a sudden, the space race was a purely civilian endeavor.

[FishInferno]

wow, I never expected this thread to attract that many people!

[Hary R]

I'm rather curious as to what this means for the age-old weapons vs armor/defensive weapons tradeoff. Or, http://en.wikipedia.org/wiki/Salvo_combat_model

You have a choice with your space battlewagon. Say you have a fixed amount of payload capacity (everything else is fuel/engines/heat radiators/etc). Do you install 1 long range weapon and use the remaining mass for armor, or do you fit as many long range weapons as you have payload for?

Let's flesh out a theoretical space battle a bit more.

First of all, scaling laws apply to warship weapons and engines.

Weapons :

A 5 meter laser mirror has twice the range of a 2.5 meter laser mirror. (it can create a spot of given area at double the distance)

A railgun that launches projectiles of a fixed mass at 10 kilometers/second has 4 times the mass of a railgun that launches them at 5 kilometers/second.

Enemy antimissile defenses mean that there is a minimum "volley size" before you do more than 0 damage using missiles to another warship.

Engines :

Orion drives are more efficient using bigger nukes, also the pusher plate has a minimum mass and a minimum thickness to work at all.

Nuclear salt water engines have a minimum size, or there won't be enough fuel in the reaction chamber for a critical mass

Nuclear-electric engines need a nuclear reactor, which is also more efficient if it is larger and has a minimum size.

So, there's a minimum size for a space warship for it to be an effective combatant, and it's probably pretty large in order to fit those 5-10 meter + laser mounts, etc.

Why not "go big or go home" and put all your resources into a single gigantic space warship?

Too big, and you get diminishing returns from longer range laser beams because at a certain distance the speed of light lag means you won't be able to hit an enemy ship that is random walking.

Also, no matter how big a space warship is, a single direct hit (warhead punches through the hull detonating inside) from a nuclear bomb will destroy it. (unless it's ludicrously large, but that's another discussion)

So there's probably an optimal size in the middle.

How might a battle go?

2 space warships, equal mass, equal technology, they are fighting over empty space for the Lulz.

At extreme ranges (interplanetary distances), one warship could simply fire a volley of nuclear missiles (robot spacecraft set to ram) and head home. It's all or nothing - either the defending warship has enough anti-missile guns to shoot down the entire volley or it gets blown up.

Assume both warships determine the other has too much point defense and they save their missiles.

Tens of thousands of kilometers : both warships are beginning to get spot sizes with lasers that are small enough to at least not waste most of the laser energy to space.

This is where armoring is important : you could make the part of the spacecraft hull that faces the enemy have a layer of liquid sodium heat pipes to carry the heat from the enemy laser weapon to your radiators. Until the beam intensity is high enough to just start sublimating your hull to gas, lasers would be ineffective.

This is also where an interesting tradeoff emerges. A laser mirror for a high intensity beam has to be a http://en.wikipedia.org/wiki/Dielectric_mirror or it will not be reflective enough. Apparently, 5 megawatts/square centimeter is achievable. However, the dielectric mirror only works for a narrow frequency range, and the coating itself has a thickness equal to the wavelength of the light used. (so just 475 nanometers for blue light).

So if your warship uses a different frequency for your lasers than the enemy, you could aim your laser weapons right at their mirror, burn just a few atoms of that delicate dielectric coating, and their mirror would now be junk and they would have to stop firing or burn up their own mirror.

But then again, both warships could hide their mirrors behind armored shutters and essentially play a game of chess where one warship exposes a mirror, the other counters by firing on that mirror, the other counters the counter by firing on THAT mirror and so on.

Once the 2 warships are done playing "the blinding game", and presumably one warship is out of mirrors but the other has a few left, they can move a bit closer and open fire on each other with railguns/coilguns.

Kinetic cannon shots will have to contain miniaturized rocket engines and guidance systems because this battle is still happening at ranges of thousands of kilometers. If both ships have orion or nuclear salt drives, each one will try to outrun incoming fire from the other, and orion drives and nuclear salt water engines are more efficient than the tiny chemical thrusters you could fit into a kinetic cannon shot. So there is a maximum range at which the kinetic cannon shot has expended it's delta V and can no longer chase after the target warship.

Both ships could also defend against incoming fire using defensive railgun/coilguns or even chemical guns to shoot down incoming kinetic rounds. This is another case where armoring matters : it would not be practical to build armor to stop an incoming slug traveling at 10 km/second or more, but you could have armor using whipple shields to block hypervelocity shrapnel from destroyed incoming rounds or fragmentation rounds that blow up before they hit your ship.

At this range, the warship who has remaining laser mirrors will have an advantage because it can either use the lasers to shoot down incoming kinetic rounds or use it to burn holes in the enemy ship to disable important systems. A science fiction, but plausible, technology that would somewhat counter this would be a nanotechnology repair system that could resurface a laser mirror in a few minutes so that the ship that lost mirrors could repair the minor damage to their surfaces and resume firing.

The shooting continues until either one warship or another surrenders, or the winning warship kills the radiators or nuclear reactors powering the loser (which stops the losing warship from being able to continue firing weapons like railguns/coilguns/lasers because he no longer has the enormous electrical power supply needed). Once the loser cannot shoot back, the winner could careful snipe all the anti-missile defenses on the losing warship and finish it off with a single nuclear warhead tipped missile. Note that radiators can be protected if they are liquid droplet radiators because you can armor the booms and even have spare booms to extend when the main ones are destroyed (since the booms are relatively small and light compared to the mass of the ship)

Honestly, this doesn't sound boring. There's quite a lot of interacting systems, and different design philosophies in the opposing warships could greatly change the outcome of the battle. It might make for a decent space simulator game, even...

Yep ,that is where I was going.

It just a speculation but for me, that ideal size is the size of our current warship, small enough to be hard to target(from very , big enough to get the useful payload of armor, radiator, weapon/defense system life support, fuel...

It might make for a decent space simulator game, even...

That's already in conception mode in my mind. If only I have someone to help me developing it. And i'm serous here.

Edited December 1, 2014 by Hary R

[dansmithers]

Everybody that I've seen in this thread seems either to be advocating cannons powered by explosives, or lasers. Neither of these is particularly practical compared to a rail/coilgun:

• Cannons release clouds of hot gas from the muzzle,which is basically a big "I'm right here, shoot me" sign for the enemy. Not to mention the fact that cannon shells carry their propulsion with them, and are therefore heavier.
  
• Lasers(at least ones with a high enough energy to cause damage) require truly huge amounts of electricity, which makes your ship a bigger target. Not to mention that , unlike kinetic weapons which can keep going(theoretically) forever, a laser actually has a limited range!
  

As for powering the railgun, a super capacitor could provide power storage, as it is unlikely such a weapon would need to fire continuously.​

A microwave based directed energy weapon might also work, though with the same drawbacks as a laser.

[cicatrix]

Everybody that I've seen in this thread seems either to be advocating cannons powered by explosives, or lasers. Neither of these is particularly practical compared to a rail/coilgun:

• Cannons release clouds of hot gas from the muzzle,which is basically a big "I'm right here, shoot me" sign for the enemy. Not to mention the fact that cannon shells carry their propulsion with them, and are therefore heavier.
  
• Lasers(at least ones with a high enough energy to cause damage) require truly huge amounts of electricity, which makes your ship a bigger target. Not to mention that , unlike kinetic weapons which can keep going(theoretically) forever, a laser actually has a limited range!
  

As for powering the railgun, a super capacitor could provide power storage, as it is unlikely such a weapon would need to fire continuously.​

A microwave based directed energy weapon might also work, though with the same drawbacks as a laser.

What concerns revealing yourself to the enemy due to clouds - put your mind at rest. It's safe to assume that all your drones/satellietes are known. You can't really hide anything from ground radars that can detect a metal footbal half the hemisphere away.

As for the rail gun - just imagine the weight of the coils you will need to fire it, also the weight of capacitors. (also some anti-recoil system too, but that goes with ordinary guns as well). Basicly, you'll need as much weight as you will need with lasers. And if we take modern technology it would still be a question which would be heavier - a gun with ammunition or lasers/microwave/railguns.

[Raukk]

What concerns revealing yourself to the enemy due to clouds - put your mind at rest. It's safe to assume that all your drones/satellietes are known. You can't really hide anything from ground radars that can detect a metal footbal half the hemisphere away.

As for the rail gun - just imagine the weight of the coils you will need to fire it, also the weight of capacitors. (also some anti-recoil system too, but that goes with ordinary guns as well). Basicly, you'll need as much weight as you will need with lasers. And if we take modern technology it would still be a question which would be heavier - a gun with ammunition or lasers/microwave/railguns.

The Traditional guns would be great for point defense and knife fight range given the reduced weight you mentioned, but the much higher velocity of a rail-gun would win out for long ranges, even at 100km you would need crazy high speed to get to the target in under 10 seconds, and 100km is short range for space. Rail-guns and lasers have the same downside, tons of mass to support the huge power budget and radiate the heat, which makes the cost for damage ratio high.

I'd personally prefer Missile volleys, the enemy knows that a few have nukes and the rest are traditional, but intercepting all of them would be hard, also shrapnel could damage or disable point defenses. The downside is the long flight time required to reach the target.

[EzinX]

Everybody that I've seen in this thread seems either to be advocating cannons powered by explosives, or lasers. Neither of these is particularly practical compared to a rail/coilgun:

• Cannons release clouds of hot gas from the muzzle,which is basically a big "I'm right here, shoot me" sign for the enemy. Not to mention the fact that cannon shells carry their propulsion with them, and are therefore heavier.
  
• Lasers(at least ones with a high enough energy to cause damage) require truly huge amounts of electricity, which makes your ship a bigger target. Not to mention that , unlike kinetic weapons which can keep going(theoretically) forever, a laser actually has a limited range!
  

As for powering the railgun, a super capacitor could provide power storage, as it is unlikely such a weapon would need to fire continuously.​

A microwave based directed energy weapon might also work, though with the same drawbacks as a laser.

A maser is just a laser that uses microwave frequency light. Unfortunately, longer wavelengths are fundamentally harder to focus to a small spot at long ranges - this is why one of the posters in this thread was advocating for X-ray lasers, even though X-rays are very difficult to focus at all.

What you are saying here is assumption dependent. I somewhat agree with you : if you had a given amount of mass available for weapons on your ship, you would do more DPS, essentially, by putting that mass into railgun/coilguns. The TLDR reason for that is the an FEL has a lot of heavy components, and a semiconductor laser heats itself up, while the superconducting magnets in a coilgun do not. So you'd probably have more kinetic energy in the coilgun/railgun shots per kilogram of weapon mass, and then physical impacts fundamentally do more damage for the same energy delivered.

The advantage lasers have is :

1. You cannot intercept incoming laser fire

2. Laser beams travel much faster than practical railgun/coilgun slugs

3. At extreme ranges, lasers can take out lasers due to the weaknesses inherent in dielectric mirrors.

The advantage hot gas cannons have is that they do not need huge quantities of electrical power to run, and they are much lighter and smaller than railguns/coilguns (with the drawback that their ammo is heavier). Their drawback is poor muzzle velocity, but they might be useful for intercepting incoming projectiles.

TLDR : I suspect there would be legitimate reasons for all of the physically plausible, practical weapon systems in a space warship using near to mid future technology. Of course, once someone works out a way to build 1 million ton x-ray laser cannons that have ranges of 1 AU are more, all bets are off.

[EzinX]

[quote name=Raukk;1571800

I'd personally prefer Missile volleys' date=' the enemy knows that a few have nukes and the rest are traditional, but intercepting all of them would be hard, also shrapnel could damage or disable point defenses. The downside is the long flight time required to reach the target.

A hybrid weapon is possible. It would be a railgun slug that has a small rocket motor. Essentially, it would be a golf ball sized slug, and the rocket motor might be a series of solid rocket propellant "pits" drilled into the slug. Electrical igniters under control of a tiny computer would set off these pits. The slug would use crude sensors to detect a carrier beam coming from the launching ship that would orient it in space and tell it course corrections in flight.

The reason to do it this way is that a railgun/coilgun is not itself subject to the rocket equation. It could send the slugs at 10-20 kilometers/second (the slugs heat up when in the armature of a railgun or barrel of a coilgun, so the limit to how fast the slugs can be launched would depend on heating among other problems) without the slugs needing to carry 20 kps worth of delta-v onboard. And that's the other problem : rocket engine designs exist that have large delta v, but those engines are things like orion drives and nuclear salt engines and nuclear electric engines. All those engines are huge : scaling laws means they cannot be miniaturized.

So missiles, by necessity, either are something that will run out of fuel quickly while chasing a target running away on orion drive, or they are essentially robot spacecraft the size of a modern day rocket or bigger that you are throwing away.

Also, you could shoot down an incoming missile the size of a falcon 1 with a railgun or coilgun slug the size of a golf ball. It hurt's the missiles delta V greatly if it tries to evade. If the missile is incoming at 20 kilometer/second, and you intercept it 500 kilometers away with a railgun/coil/laser beam, then your spacecraft has 25 seconds to get out of the missile's shrapnel cloud. If your spacecraft has an orion drive or nuclear salt thruster able to accelerate at 10 m/s^2, then it could "dodge" by 3 kilometers and avoid the big pieces from the missile's debris cloud. (and a whipple shield could soak up the paint chip sized flecks of missile that would probably be in that debris cloud as well)

Of course, you could give the missile point defense cannons to shoot down incoming railgun/coilgun slugs bound for it, but then you could still shoot the missile down (by shoot it down, I mean put a hole in it to disable it's ability to maneuver and/or blow it up, obviously there is no down in space) with laser beams. Of course, then you could stick laser beams on the missile to snipe enemy laser beams...

TLDR, the missile ends up being the size of an entire warship, and you are using the strategy Ramming Always Works. Truth in television, indeed.

[cicatrix]

The Traditional guns would be great for point defense and knife fight range given the reduced weight you mentioned, but the much higher velocity of a rail-gun would win out for long ranges, even at 100km you would need crazy high speed to get to the target in under 10 seconds, and 100km is short range for space.

Put some physics to this. 10 km/second for a 1 kg slug results in momentum of 10 KN*s. According to Newton's second law you will need to compensate the equal retrograde force. Same for guns, as I said. When your slug starts to move the vector of its movement MUST be precisely on the prograde vector and precisely on the center of mass of the launching vehicle - a tiniest deviation of the target (or of the launching vehicle which seems very likely due to recoil and angular momentum if your rail gun is off the center of mass) and you'll miss.

Besides, you ALREADY fly at 8.9 km/s in LEO. Adding 10 km/s of dV will put your slug on an escape trajectory and since your slug is not controlled - it is firing at the skies...

Railguns are probably the MOST ineffective way of fighting a war in orbit.

Add this:

Rail-guns and lasers have the same downside, tons of mass to support the huge power budget and radiate the heat, which makes the cost for damage ratio high.

And finally:

I'd personally prefer Missile volleys, the enemy knows that a few have nukes and the rest are traditional, but intercepting all of them would be hard, also shrapnel could damage or disable point defenses. The downside is the long flight time required to reach the target.

We come to a conclusion that guided/homing missiles are the most cost-effective, reliable, and powerful weapon available in orbit.

Edited December 2, 2014 by cicatrix

[EzinX]

We come to a conclusion that guided/homing missiles are the most cost-effective, reliable, and powerful weapon available in orbit.

Cicatrix, the wall of text located directly above yours explains the reason why guided/homing missiles are not necessarily the best.

Regarding Newton's second law : that is an issue but it is in principle possible to build a railgun aiming system that compensates for that, or to mount your railgun in line with the center of mass of the ship. You can think of the movement of the ship as you fire as adding an unwanted velocity vector to the shot. Subtract that unwanted velocity vector from your intended velocity vector, and you have the new velocity vector you want your railgun system to impart to the projectile. Then have your aiming system calculate an angle and a switching sequence to deliver that vector.

The new firing "plan" as it were (a plan would be a series of settings for the railgun weapon system, such as switch timings, how much the capacitors are charged, and of course the angular settings of the servos controlling the barrel) you then have to evaluate again against your dynamics model of your ship to find out what the new unwanted velocity vector is (it's different now since you changed things). You iterate until the shot is "close enough" to hitting the target that rocket motors in the railgun round itself can provide the teensy bit of correction needed for a direct hit.

[cicatrix]

About the accuracy - 0.1 mm difference off-axis at 1 meter will result in a 1 meter miss at 1 km and 100 meters miss at 100 km. Can you provide such a precision? And why should you?

P.S. Even if you can provide that (which I doubt) you should also think of your coils - they should form completely uniform and even magnetic field distribution along the firing vector. Moreover, the slug itself should be made of metal with ideal atomic mesh structure. A slight defect in one cable leading to a coil or a tiny impurity of metal might cause that tiniest inclination necessary for you to miss.

P.P.S. As for 'rocket powered slugs' - I don't see any advantages versus the good old missile. The complexity and expensiveness of the launch platform will negate all possible benefits. Missile can be slow, but it can maneuver.

Edited December 2, 2014 by cicatrix

[EzinX]

About the accuracy - 0.1 mm difference off-axis at 1 meter will result in a 1 meter miss at 1 km and 100 meters miss at 100 km. Can you provide such a precision? And why should you?

P.S. Even if you can provide that (which I doubt) you should also think of your coils - they should form completely uniform and even magnetic field distribution along the firing vector. Moreover, the slug itself should be made of metal with ideal atomic mesh structure. A slight defect in one cable leading to a coil or a tiny impurity of metal might cause that tiniest inclination necessary for you to miss.

P.P.S. As for 'rocket powered slugs' - I don't see any advantages versus the good old missile. The complexity and expensiveness of the launch platform will negate all possible benefits. Missile can be slow, but it can maneuver.

I think I've established the benefits. If you can get a railgun muzzle velocity of 20 kps (I can link you to patents that describe how to build one on paper), then here's your tradeoff :

Missile case : chemical engine ISP of 400. Good ole rocket equation says to hit 20 kps you need to throw away 94% of the mass. Not to mention tank mass, and you're going to probably want stages. Want a nuclear engine? Then the minimum size of your missile becomes gigantic because nuclear reactions require a critical mass, I was estimating a nuclear engined missile at the size of a Falcon 1.

Railgun Case : You essentially launch the kinetic interceptor package at the very top of the missile used in the missile case in the railgun. Kind of like this one, but with radical design changes to tolerate the incredible g forces at launch.

In a battle against an enemy vessel who has defenses and the ability to maneuver rapidly with large dV reserves (aka various fission drive variants), you're going to need a sustained barrage of fire to destroy them. If you have a railgun/coilgun, you can haul at least 33 times as many munitions.

Also, surprisingly, I think both vessels would be surprisingly hard to kill, despite being spacecraft and very lightweight. Laser weapons that can disable enemy laser weapons but lack the firepower to do significant damage to the enemy hull (essentially, anti-laser lasers) are lighter than offensive laser mounts. Incoming missiles, especially big ones like you advocate for, could be disabled by using small railgun/coilguns to fire golf ball sized hypervelocity slugs. Just 1 hit from a slug at 20 kps will kill any plausible missile.

Honestly, it could easily turn out that all the systems we have mentioned aren't all that effective and that the only way to go is something like a fission bomb pumped X-ray laser.

Edited December 2, 2014 by EzinX

[Mazon Del]

I enjoy this topic for a lot of reasons, so I figured I'd toss in my side of things.

In a space fight, you want one of two things. The enemy destroyed, or the enemy incapable of performing their mission. These two are not necessarily the same thing, but are equally as effective.

Supposition 1: The craft in question has a limited amount of fuel.

Supposition 2: The craft has enough fuel to make it from a starting orbit around its home, to the target planet/moon/etc, enter an orbit around said target, return home, orbit home, some extra amount for maneuvering/fighting.

Supposition 3: Standard drive technologies in use (basically chemical, NERVA, ION, whatever. But no Q-Thruster type systems. [Enjoy that Kerikbalm ])

Supposition 4: Head radiating ("cooling") technology works roughly as well as it does now.

Supposition 5: The craft will be manned.

Supposition 6: Both sides know the fight is coming or are already at war. IE: No surprise attacks.

Supposition 7: Both sides have multiple ships.

Supposition 8: Excluding when part of a fleet or in orbit near an inhabited location, a ship without engines will be unlikely to receive aid.

Given these 8 suppositions and a basic understanding of physics one can extrapolate out a great many things about the ships.

Extrapolation 1: Bigger ships will require more fuel to accelerate/maneuver to the same degree as smaller ships.

Extrapolation 2: The greater the physical requirements of the weapons, the greater the ship will mass.

Extrapolation 3: Ships will generally require engines capable of endurance burns (planet to planet travel), but also burst burns ('dodging').

Extrapolation 4: The direction that projects the maximum firepower of a ship will also present a minimum of risk to the engines.

Extrapolation 5: The direction that projects the maximum firepower will endeavor to minimize the visible footprint of the ship.

Extrapolation 6: To some extent the ship will provide protection to the engines from the side.

Extrapolation 7: The fuel storage requires at least as much protection as the engines, preferably more.

Extrapolation 8: The thermal radiators will require some level of protection.

As a result of these extrapolations I believe it is fair to state that a likely warship design ends up being something resembling a cone (there are pros and cons for making this a longer or shorter cone) with a bit of a "bowl" area in the rear. The engine(s) will be largely embedded within the bowl area in the back, and the fuel storage will be in the center of the ship, just forward the engines. The main thermal radiators will likely be focused in the rear of the ship in either the main 'bowl' or in their own similar enclosures. Expendable/stowable radiators will be on the cone itself, minimizing footprint to enemy, but not impeding ship systems. The usual assortment of thrusters for orientation/dodging will exist on the hull, likely with several backups. If the ship is expected to be going on a heavy war footing, then there would additionally be hardpoints to mount 'disposable' systems. IE: Increased fuel, heavy missiles, possibly things like SRBs, all things that can/will be tossed once used up for mass reasons. There will be 1 forward facing engine, for specific instances requiring large reverse thrust.

Reason 1: Any weapons on the outer surface of the cone can face forward, providing a maximum firepower orientation.

Reason 2: With the cone pointed towards the target, a minimal footprint of the ship is presented (less area for the enemy to target).

Reason 3: With the cone pointed towards the target, the maximum effective mass of the ship is between the enemy and the fuel/engine section.

Reason 4: This shape presents an angled surface to the front and to perpendicular directions. Sloped armor provides additional defense from any hit not perpendicular to the slope.

Reason 5: In the event that the tactic of rolling the ship is necessary (preventing a laser from holding its spot?), you are still presenting a sloped surface to physical munitions.

Reason 6: In all but the most up-the-skirt style shots, the engine bell(s) are not exposed, indeed the shape of this location may provide a slight extra thrust boost as it could act as a larger bell.

Reason 7: The thermal radiators will be protected and in cases where no risk of damage from the side exists, they could extend backwards to increase efficiency (less radiating onto the ship itself).

Reason 8: More radiators is pretty much always going to be better than less (only mass/stealth [hah] constraints are really going to restrict these).

Now onto weapon systems.

The most likely load out for these ships is going to have a relatively heavy complement of lasers/masers, a few railguns (2 minimum for full coverage), a bay for a limited assortment of small missiles.

Assuming the war footing mentioned, the ship would likely launch with several heavy missiles (3-5) attached the external hardpoints as well as some extra fuel tanks and a couple SRBs. In a scenario of a fight between say Mars and Earth, the ship assigned to defend Mars would likely utilize the SRBs alongside the main drive to get it the initial high thrust kick out of Mars orbit and on its way to intercept an attacking Earth ship. Once something approximating an intercept (at least insofar as the ships will be entering each others weapons ranges [note: YES railguns have a "range", this is determined by the dV they can impart on the shots. Not enough and they cannot reach their target's orbit.]) was assured the Mars ship's opening move is the launch of the external missiles. All fuel utilized by the ship will be from the drop-tanks. Detaching can happen to increase maneuverability, decrease footprint, or because they are empty. At this point I need to pause to explain the tactics of the Mars ship.

Going back to the beginning, a destroyed ship cannot complete its mission. This is desirable. A ship can be made incapable of completing its mission without being destroyed. This is also desirable. If you can incapacitate the crew, the combat ability of the ship is vastly decreased, namely in that repairs cannot be made. If you can destroy the ships engines, then you have removed their primary method of changing vector. This LIKELY means that the crew is going to die. Without another ship capable of intercepting it physically to transport repair materials or to offload the crew, the ship will never change vector and will either hit something, or likely enter some abysmal solar orbit far from help. Additionally, if the ship cannot execute large vector changes, it becomes that much easier to target for eventual destruction. The same eventuality occurs if the fuel supply is lost or expended.

The plan of the Martian ship is to force the Earth ship to maneuver itself into uselessness. Those missiles of yours will likely spread out a nice distance to both minimize the chances of being hit by the crossfire, but also to allow a greater chance that one of them will be in position to strike at the Earth ship. They will occasionally need to exert course changes in order to meet up with the Earth ship. The Earth ship has a choice, if it wants to, it can spend fuel dodging around in the hopes of forcing the missiles to waste too much of their fuel to allow for an intercept. Or, he can not care and just hope for the best. Note: The Earth ship has the advantage against the missiles. It knows the missiles want to hit it, so it knows where the missiles will try to put themselves. But the missiles don't know where the ship will try to put itself. Given this, the Earth ship can be imagined to have nigh-instant knowledge of what the missiles are doing and roughly when. If it shifts up, the missiles will need to shift up. Due to the light lag the missile has no way to tell if a 1 second up burn is going to stop at one second or not until that time has passed. If the Earth ship fires the main engines up for one second, then slams on the reverse engine (told you it would have a use) for 10 seconds, and the ships are at a range of 10 light seconds, it has executed a relatively massive vector change before the missiles even saw it happened. The missiles will begin reacting to the first burn before needing to react to the second. Meanwhile they don't know where the ship might be going to next.

Now I can continue on the logic, counter logic, etc, of missile vs ship combat. But in the end the result is that the ship is going to be spending fuel, probably whole lots of it. Now those of you who favor missiles are probably asking what the point of the rest of the weapons are when you have those missiles. Remember, while your missiles are on their way, you don't really have much to do. Adding more missiles won't really change what is happening. More missiles only means that you can repeat this process after the first have hit or missed. But more missiles with useful amounts of dV means you get much heavier, and thus less capable of dodging the enemy and HIS missiles. Now, while the enemies ship is bandying around in its fuel based chess match with the missiles, it is time for the lasers to make an appearance. Your lasers are not designed to burn through the enemy ship, no, that is certainly silly at these ranges. Your lasers are simply designed to dump as much heat as possible into the enemy ship. Remember all those radiators? You need them because YOU will be generating quite a lot of heat firing these beams, but also because you are going to likely be hit BY the enemy beams as well. You both are going to be sitting there trying to cook each other. You have an advantage over your missiles. While you still have the same light lag as they do (worse, since they are approaching the enemy at a faster rate than you, they are closer at any given instance of time and thus have less lag to deal with), you have the advantage that the Earth ship cannot tell where you are positioning your shots. Oh, like with the missiles, he can assume that your beams are going to be bracketing his ship (say 40% across the forward arc, 30% across the rear arc, 10% incase he translates 'up' and 10% for 'down', and 10% straight at him. While you may or may not have 10 lasers to fire, this rough distribution is probably the best to start with if they are being particularly dodgy, but of course adjust as necessary), so it really doesn't matter much which way he picks, he'll run into your flash-light beams of heat and pick up some for himself. Now, this isn't totally a very efficient exchange rate of heat generated vs heat deposited. At this point in the combat, that is perfectly fine. The more heat he picks up from your lasers (especially from running the engine as well) the better. As he heats up, he is going to need some method of dumping the heat that is faster than just radiators (especially because any radiators you are managing to hit with your beams, are losing their efficiency). Assuming that the fuel of both ships in question ends up being not a monopropellant, then you are both going to do the same thing. You are going to flush your ships in fuel to boil off the heat.

Let's assume you are both working with good old chemical rockets. Flush your radiators, engines, and weapons with some of that liquid/gaseous hydrogen and boil it off into space. Chances are the heat in your ship has been building up pressure in your fuel tanks, since you have to vent it anyway, might as well have it take as much heat as possible. Starting with those external tanks you might still have of course. The hydrogen isn't dangerous until it comes into contact with the oxygen. Which you will of course use "last" considering that if you'd lost life support, you'd rather have a bunch of extra oxygen than a bunch of hydrogen lying around. But once the fuel levels start getting unbalanced enough, switch over until they are equal again, then go back to hydrogen. Now what is this doing? Its making your enemy dump fuel! During this whole exercise, do not bother firing the railguns. They will generate heat you do not have the thermal budget for, for zero gain. The enemy ship is ALREADY dodging missiles (and technically your lasers), your railgun rounds are just going to miss and they get no utility out of causing him to waste extra fuel. This is because at the distances you are still fighting on, the Earth ship is not going to be anywhere near where you targeted the railgun rounds by the time they reach him. Bracketing him is worthless at these ranges since the necessary bracket size would have you quickly deplete your ammo stores. What you are going to want your railguns for at this point in time, is missile defense. You have the magic knowledge of where the missiles are going to be and what they are doing before the light of this event reaches you. Remember, they have to hit you, so they MUST react to you. You know what they have to do to hit you, so you can predict what they are doing. Sure they might not follow this prediction, but its a safe bet they will.

In the end though, lets assume that all the missiles have missed or otherwise been destroyed. While you are still at these absurd ranges, the fight will stick mostly with the lasers. You will occasionally potshot at/around the Earth ship, but this is mostly just to verify his fears that he needs to occasionally burst just a tiny bit from his thrusters/engines to change position to dodge. More fuel waste. Meanwhile the whole time, you two are lazing each other, dumping fuel for heat purposes, and maybe executing a major dodge to get a couple seconds reprieve (if your engine's heat efficiency is that good). Eventually though, assuming one crew hasn't managed to broil the other alive yet or surrendered, the ships will enter into railgun range. Where the cost of bracketing the enemy ship isn't very high. Now is when any last trump cards you have for heat come into play. The closer range means both that the railguns matter a lot (if you hole their engine or fuel source, they are out), but that lasers will hit more accurately, but now everybody needs to use their engines to dodge. At this point its a grudgematch to the death, play all the games you want with rotating ships, beam/railgun sprays. The victor will be determined most likely by who entered with the larger capacity to suck more heat. If not, it was then determined mostly by luck of the draw.

At this point you might ask why bother having those small missiles that I had mentioned earlier? Simply because there are some situations your warship might find itself in that lend itself towards missiles rather than railguns or lasers. These situations are generally speaking only when the ships are at obscenely close ranges for space ships, such as in the same orbit as each other. They likely wouldn't have the dV necessary to perform an intercept on an interplanetary intercept. Lets say you need a nuke for some reason, these missiles at least let you have that without the expense of a full on system missile.

Now of course the whole darn thing changes if Q-Thrusters ARE real...no fuel requirements, absurd accelerations (and thus closing speeds), fuel-less missiles, etc.