Whay would real-life war spacecraft look like?

[kerbiloid]

50 minutes ago, magnemoe said:

An torpedo boat would make sense, an fighter is designed for an short duration mission 6 hour or shorter, life support and crew facilities as in an seat is designed for this. 

... and limited fuel, limiting its maneuverability with closest orbits.

This means that you would either permanently support numerous gunboats on different orbits with crew and supplies,
or several gunboats could perform only peripheral tasks on several orbits, still eating and needing support.

Taking MOL/Almaz/Mir/ISS as default, you would send a crew+supply mission every three months.
In a year the total mass of supply ships will be greater than the gunboat itself.
Several years later you would realize that you've already sent an order of magnitude more mass of supplies than a gunboat weights itself.

And then would be asking yourself: why not just launch ten gunboats on demand (say, 9 were hit on ground, but 1 survived and started), rather than spend a whole fleet of supply ships to support them.
And if send them on demand, their orbital life will last for 1-2 hours, and who needs that overcomplicated gunboat.

Problem is not in gunboats, problem is in their support. Much easier to support 1-2 big stations, than several tens independent gunboats, each requiring a separated launch of supplies.

Also don't forget that after a 3-month flight the crew needs, say, a year of medical procedures to resurrect. 
(Rather than RL spacenauts, they should perform tens of flights per career and stay healthy all the time).

This means that if a gunboat has a crew of 3, you should have at least 15 crewmen per gunboat in total: 3 onboard and 4x3 on ground.
For 20 gunboats you need about 500 space pilots, while their firepower is not very significant.

Edited July 5, 2017 by kerbiloid

[magnemoe]

4 minutes ago, kerbiloid said:

... and limited fuel, limiting its maneuverability with closest orbits.

This means that you would either permanently support numerous gunboats on different orbits with crew and supplies,
or several gunboats could perform only peripheral tasks on several orbits, still eating and needing support.

Taking MOL/Almaz/Mir/ISS as default, you would send a crew+supply mission every three months.
In a year the total mass of supply ships will be greater than the gunboat itself.
Several years later you would realize that you've already sent an order of magnitude more mass of supplies than a gunboat weights itself.

And then would be asking yourself: why not just launch ten gunboats on demand (say, 9 were hit on ground, but 1 survived and started), rather than spend a whole fleet of supply ships to support them.
And if send them on demand, their orbital lifetime will last for 1-2 hours, and who needs that overcomplicated gunboat.

Problem is not in gunboats, problem is in their support. Much easier to support 1-2 big stations, than several tens independent gunboats, each requiring a separated launch of supplies.

Yes, however any setting with maned warships demand better drives.drives is also an limiter, if you use orion pulse nuclear you can just as well build an batleship. 
Various fusion types would work for an gunship. And out past the gas giants mission times will be to long for them. 
Might be useful as an destroyer screen but that can also be done unmanned as it will stay close to the mothership 

[kerbiloid]

With fusion drives - of course, that's another tale. I meant near future.

[DDE]

6 hours ago, magnemoe said:

fire control closer to target

That's not an issue you need to worry about. The Earth-Moon system is all within a few light-seconds.

5 hours ago, kerbiloid said:

With fusion drives - of course, that's another tale.

They're not.

Torchdrive-class fusion rockets with militarily useful thrust are.

[ouion]

The Short Answer: We don't know until a space war breaks out

The long Answer: We could guess,right?

On the side note, The Expanse presents a not bad representation of a spacecraft built for war

For Real Life:

Size: It depends on whether there is a crew or not. If there is a crew, then the spacecraft will be designed to have life support and crew living quarters and ample amount of space for maximum crew comfort. A unmanned spacecraft would be even smaller, probably equivalent to satellite, of course with weapons. You could even go smaller to nano meter sizes. Think of swarms of nano machines in space fighting other nano machines or destroying whole planets. It would be more logical to have  a unmanned spacecraft to fight our wars. 

I'am also thinking of hitting planets with projectiles accelerated to a near the speed of light instead of having spacecraft fight in space.

Its important to know that space is not a ocean.

Space fighters will probably be space planes firing anti-spacecraft missiles, they probably will be on a suborbital trajectory. Its very likely they would be unmanned,

Weapons:  It depends on the time period, in the cold war. The USAF has a plan for a Orion nuclear spacecraft armed with a nuclear warhead and 3 inch naval guns for self-defense. People mostly think of lasers and rail guns to be on spacecrafts in war. Why not include a traditional naval gun probably with ECT(Electro-Chemical Technology) and other improvements? Something like the CIWS would be important on spacecraft for shooting down missiles or space fighters. I think of two types of missiles: One for close range and for long range. The close range would be something like the AIM-9 sidewinder that launch in close range. A long-range missiles would be like a probe or a nuclear missile that target other spacecraft far away or not in reach.

Appearance:  Think of a NASA proposed Orion nuclear powered spacecraft or Constellation Mars transfer vehicle combined with a tank. Its very unlikely, they would be built like ships on Earth. For projectile protection; something like a wipple shield or spaced armor to stop rail gun rounds or angular armor like a tank to increase thickness and chance of round ricochet.

 

 

 

[DDE]

3 hours ago, ouion said:

One for close range and for long range. The close range would be something like the AIM-9 sidewinder that launch in close range. A long-range missiles would be like a probe or a nuclear missile that target other spacecraft far away or not in reach.

I highly suspect that the need for terminal maneuverability will bring back liquid-fuelled missiles. A Sidewinder is basically a guided bullet after its solid motor burns out.

3 hours ago, ouion said:

chance of round ricochet

At railgun velocities this is basically hopeless. Note how modern tanks are in many cases giving up sloped armour.

[SaturnianBlue]

War spacecraft would probably be pretty pointy to deflect enemy shells and increase the effective armor thickness. I don't know if it would work for particularly high velocity weapons, but maybe for conventional guns strapped on drones they would definitely work.I'd imagine most of the armament would be forward-mounted to increase protection and firepower at once. Missiles would also be pointed shaped so that oncoming fire would get deflected. 

[Confused Scientist]

At its basic core, the same as any military vehicle: tons of fuel, tons of bombs, and only basic amenities for the crew (because no matter how long we argue, there will be a crew on something someday.) Also, I think instead of armor, spacecraft would take extreme evasive maneuvers and tons of them would be blown up by tiny stuff. So, we just build some more! Hey, what happened to all of the government's money?

'Two birds with one stone' idea: Project Orion, where you put your enemy 180 degrees away from where you want to go.

[RoadRunnerAerospace]

a space battleship? Unrealistic. Largest thing out there would be a corvette, why consolidate all of ye`s forces into one massively vulnerable ship that can`t maneuver+has terrible deltaV? With a bunch of smaller ships, you can maneuver around/out of the way easier, and have overlapping CIWS (is that right?) coverage. now, with lazers, they can all focus on a point (mentioned earlier in the thread), causing more condensed/critical damage than 1 large lazer that dissipates.... Not to mention, if one ship is destroyed, there are more ships to continue the fight. 

[Joseph Kerman]

Just now, RoadRunnerAerospace said:

a space battleship? Unrealistic. Largest thing out there would be a corvette, why consolidate all of ye`s forces into one massively vulnerable ship that can`t maneuver+has terrible deltaV? With a bunch of smaller ships, you can maneuver around/out of the way easier, and have overlapping CIWS (is that right?) coverage. now, with lazers, they can all focus on a point (mentioned earlier in the thread), causing more condensed/critical damage than 1 large lazer that dissipates.... Not to mention, if one ship is destroyed, there are more ships to continue the fight. 

Correct. There is no point in building a Star Destroyer with our current technologies. The best we could do would be a VASIMR-powered probe fighter with 12 WWII HVAR's (Sidewinders are pretty much the same as that in space anyways) and maybe a 50 kW infrared laser powered by solar and fission energy. In fact, we could have 12 of those by 2055.

[Kryten]

17 hours ago, RoadRunnerAerospace said:

a space battleship? Unrealistic. Largest thing out there would be a corvette, why consolidate all of ye`s forces into one massively vulnerable ship that can`t maneuver+has terrible deltaV? With a bunch of smaller ships, you can maneuver around/out of the way easier, and have overlapping CIWS (is that right?) coverage. now, with lazers, they can all focus on a point (mentioned earlier in the thread), causing more condensed/critical damage than 1 large lazer that dissipates.... Not to mention, if one ship is destroyed, there are more ships to continue the fight. 

Why would a large spaceship be any less maneuverable than a small one?

[SaturnianBlue]

28 minutes ago, Kryten said:

Why would a large spaceship be any less maneuverable than a small one?

I suppose that people can't help but think in terrestrial analogues, where bigger generally means less maneuverable. For that matter, why would it have terrible delta-V? 

I had an idea for a group of ships that would piggy-back aboard a large supply ship, and would use higher thrust but possibly lower Isp engines. They'd be fairly expendable and could attack larger ships, before retiring to the supply ship and restocking. The main problem I can see with this is the huge dependence on the supply ship.

[RoadRunnerAerospace]

 

 

1 hour ago, SaturnianBlue said:

I suppose that people can't help but think in terrestrial analogues, where bigger generally means less maneuverable. For that matter, why would it have terrible delta-V? 

According to many-a-sources (aerospace engineering textbooks, etc.) you would want to have a larger engine bell to increase Isp, correct? larger engine bell=more mass not to mention all of the weapons systems consolidated on one ship would require that nuclear reactor to be the size of, like, texas to provide enough power to the lazers, and if it is hit, the entire ships goes with it, requiring more armor to protect it, requiring more deltaV to get around, requiring a higher Isp. More ships with one or two lazers take advantage of "concentrating all firepower" on the enemy fleet, thus focusing more (again, earlier in the thread), and being more accurate, and powerful. the only way I can think of getting around the engine bell problem is to have lots of smaller engine bells (N-1 kinda thing). I will admit that I forgot about space`s spacy-ness, and went to "terrestrial analogues" though....

[Casualnaut]

Phhhh!

The Russians attached a fighter-jet cannon to their space station, and it worked. 

[SaturnianBlue]

11 minutes ago, RoadRunnerAerospace said:

 

 

According to many-a-sources (aerospace engineering textbooks, etc.) you would want to have a larger engine bell to increase Isp, correct? larger engine bell=more mass not to mention all of the weapons systems consolidated on one ship would require that nuclear reactor to be the size of, like, texas to provide enough power to the lazers, and if it is hit, the entire ships goes with it, requiring more armor to protect it, requiring more deltaV to get around, requiring a higher Isp. More ships with one or two lazers take advantage of "concentrating all firepower" on the enemy fleet, thus focusing more (again, earlier in the thread), and being more accurate, and powerful. the only way I can think of getting around the engine bell problem is to have lots of smaller engine bells (N-1 kinda thing). I will admit that I forgot about space`s spacy-ness, and went to "terrestrial analogues" though....

Definitely true for chemical engines—not sure about more advanced ones like fusion though. I suppose you could get around the issue of needing reactors by using mostly missiles and kinetic weapons, though of course the former can be shot down and the latter takes rather noticeable amounts of time to reach the target. As for delta-V, ships could just carry drop tanks with them, and drop them—they might make the ship vulnerable, but they would probably be used for an intercept burn only. Having multiple engine bells would also make the ship more redundant, which would be very important in combat, where the ships would be unable to repair quickly enough. 

As for lasers, couldn't the ships just mount two or more? 

Edited July 19, 2017 by SaturnianBlue

[RoadRunnerAerospace]

True, missiles would be the dominant close range combat (100 miles or so, where enemy's can`t react, but still get enough "oompf"), but at farther ranges, they are basically useless, they`re too easy to dodge/destroy with CIWS. Drop tanks have one major problem in space combat, they are combustible, and hinder a ship`s maneuverability (who wants drop tanks riding a freaking roller coaster?! They could break something!) the best option is to drop them as far away from the combat as possible, and fetch them later, leaving they`re precious fuel vulnerable (I think space combat would have a lot of depletion warfare (i cant think of its name)), and you cant choose when you`re attacked. 

Kinda interesting: https://en.wikipedia.org/wiki/Soyuz_P

[kerbiloid]

7 hours ago, Kryten said:

Why would a large spaceship be any less maneuverable than a small one?

1.Moment of inertia ~mr². Required power grows faster than size. While the power itself is more or less proportional to mass (r³). 

2. Also for the same maneuverability this means greater waste heat per mass and a problem with radiators which have to have greater size and stronger construction (so, in turn, the hull must be more massive).

3. If in a fighter cabin (turn radius = several meters) the pilot feels like a cowboy lying under a horse, in a battleship, with same angular velocities and with the turn radii ten times greater, he would have his brains squished out.

Spoiler

The maneuverable battleship crew would have nickname "Popeye sailor". Not only for braveness, but (mostly) for eyes popped out .

 

Edited July 19, 2017 by kerbiloid

[Joseph Kerman]

Honestly, starting with LEO dogfights, scramjets with insertion and retro thrusters with reaction control nozzles would be sufficient. How to rendezvous? Time it right, since you only really have one orbital period (of enemy craft) to act onto.

Edited July 20, 2017 by Joseph Kerman

[DDE]

On ‎21‎.‎07‎.‎2017 at 1:52 AM, Joseph Kerman said:

Honestly, starting with LEO dogfights, scramjets with insertion and retro thrusters with reaction control nozzles would be sufficient. How to rendezvous? Time it right, since you only really have one orbital period (of enemy craft) to act onto.

Scramjets can handle only about a third of requisite dV.

[Joseph Kerman]

6 minutes ago, DDE said:

Scramjets can handle only about a third of requisite dV.

Well how would you propose during atmospheric ascent? 

[tater]

Any talk of space warfare and realism needs to very explicitly set the parameters.

What time frame?

What laws of physics are broken?

What is the context that reasonably produces the need for such craft?

 

In any foreseeable future, we're talking about satellites in Earth orbit shooting at other satellites or ballistic missiles. Manned warships are not a thing. Conflict past Earth? Not a thing.

In a distant future with exploitation/colonization of space? I don;t think warfare is a thing. Killing everyone is too easy---wehn conventional weapons act like nukes, people will use them as often as we use nukes, which is to say not at all.

Break a law of physics and add FTL? Now you can have people expanding in such a way that while resources are functionally infinite for living in cans, good planets are very rare, and perhaps result in conflict. To talk about those fights, we'd need very specific parameters on what is possible in that universe technologically, then we can see what the warfare might look like.

[DDE]

1 hour ago, Joseph Kerman said:

Well how would you propose during atmospheric ascent? 

A kerolox rocket engine is a lot more efficient than any chemical airbreathing system, even if used as just the first stage. With non-chemical airbreathing systems, you move into very vague territory, so see

1 hour ago, tater said:

Any talk of space warfare and realism needs to very explicitly set the parameters.

What time frame?

What laws of physics are broken?

What is the context that reasonably produces the need for such craft?

And as to @tater,

1 hour ago, tater said:

To talk about those fights, we'd need very specific parameters on what is possible in that universe technologically, then we can see what the warfare might look like.

Or what time period the authors are into.

 

Edited July 22, 2017 by DDE

[kerbiloid]

10 hours ago, tater said:

What laws of physics are broken?

Discovered.

10 hours ago, tater said:

Break a law of physics and add FTL?

And time machine.

All wars of Far Future are already finished billions years ago, when the time troopers of the Sacred Order of Lime Tentacle successfully turned the evolultion to the present way,

[tater]

Most SF break some physics. Postulating any new discovery should make the author of the scenario chase down the repercussions as well as they can. Look at drives with huge Isp and decent thrust alone, that makes creating world-killers (extinction level events) pretty easy.

[Green Baron]

Looking at my shaver i think it was designed after a real life space warship (or war spaceship ?) whatever ...

:-)