Hard Sci-fi and ship based weapons.

[Mr Bean]

Realistically, missiles would likely be using chemical rockets, because nuclear doesn't scale down well. They'd have higher accelerations than the nuclear rocket powered ships, but lower delta Vs, so they'd have a definite range limitation, though exactly what it would be depends on the precise speed and orientation of the opposing ships and what acceleration they're capable of.

That assumes you don't use multi-stage rockets, they won't slow down after all. You kick in a main stage with a powerful booster to get the KPS up as high as possible with a smaller more fiddly engine with better handling abilities once it gets X miles away.

Also as noted you have the possibility of putting mass drivers in your ships to give the missiles a high initial speed the engine will only boost.

*Edit the main issue with missiles is how smart you can make them. After 100k miles your talking about light-speed delays for commands from the base ship.

[Darth Wong]

If the ships are "hard sci-fi" apart from their FTL, they probably can't build up a lot of sublight velocity. Not if they expect to be able to decelerate, go into orbit, and land troops on the planet.

An invasion fleet would either have to drop out of FTL very close to the target planet or accept that it will take months to approach the target planet once they drop into the system from a greater distance.

Just something to keep in mind. This ain't Star Trek, where a ship drops out of FTL near Mars and shows up at Earth in minutes.

[Mr Bean]

Except that there an enormous number of factors that influence this and it's effectiveness. First of all it's pretty much useless without knowing how fast ships can change direction and what speeds they can accelerate their rounds to. How much armor do they have? What's the approach angle? Can the gun fire fast enough to limit the enemies maneuvering options? Does the bullet carry any sort of warhead? What kind of thermal/kinetic resistance does their armor have? How fast can they throw a railgun shell? How good is their laser focusing? How visible are the rounds on incoming sensors? How good is their tracking software at generating a firing solution? How fast is the firing ship going?

Well let me break it out for you.

Simple physics time!
If we have two ships doing lets say 10 Kilometers a second(Escape velocity from earth being 11ish kps.

Ship A and Ship B are doing the same speed, they are flying towards each other since that's the easiest targeting range, they start one million kilometers apart. Just for refrence FYI the Apollo space-craft could do this, mounting weapons on them would be hard but if we wanted to sling them into space and return them back we could send then out that far.

Both ships will not be building up speed to make the math easy. Both are doing 10 Kps steady. Lets say both are armed with 80 KpS railguns, add in the ships velocity we get a nice 100 KPS speed as either ship fires at the other. Note we don't have any railguns that fire that fast yet, but we could get missiles that fast.

Ok, at one million kilometers it would take 166.6 minutes for a projectile to travel between the two ships. At which point both ships would have moved 100,000 kilometers and would be 200,000 kilometers closer to the enemy ship.

At that range(One million kilometers) a one centimeter drift in any direction would result in the ship being (One centimeter for every 10 kilometers it moves) it would be one kilometer off it's initial X grid position by over a kilometer, so even with a one centimeter drift it would be over a kilometer out of position when it was fired at.

That's one centimeter what if it was 138 centimeters(IE human walking speed?) well it would be over 1380 kilometers off it X's position.

Starting to get a grasp of how hard it is to hit a ship that's has ANY ability to dodge at those ranges?


Ok lets make things easier, it's been hours since the ships started out, now they are only 50,000 kilometers apart. Now Ship A fires at ship B, it takes 500 seconds for the projectile to fly towards the target ship which will move 5000 kilometer closer. Again lets see if it walks out of the way, it will be .69 kilometers out of it's X or Y position just going 138 centimeters a second in some direct(walking speed)

Ok how about 10,000 kilometers
Now we are down to 100 seconds, 138 meters or .138 kilometers out of it's X position.

How about 2,000 kilometers? Now we are talking now it just has enough time to walk 27.6 meters out or range, you might get a hit then if you spray enough rounds. However by the time you've fired the ships will be in knife fighting range(IE less than 500 kilometers) and if you've not hit him by now you have another five odd seconds of firing before he's past you.


Note this was based on two ships that could only make slight X/Y/Z changes.

Even slight slowing down and speeding up by just a few centimeters is enough to dodge anything over 50,000 kilometers almost by accident at lower speeds you can still walk away. And if you can do a few meters in any direct you can dodge up until you hit 5,000 kilometers.

If your ship can do anything over twenty meters a second in any direction (45 Mph or 72 KpH) it can dodge all the way up to 1,000 kilometers most likely unless you get luckily. After which hits become possible.

FYI, 3-4g's is all you'll take from a 20 meter/second burn so easily survivable without any kind of internal compensator.








I'm not arguing that a projectile weapon is going to have a longer accurate range than a laser.

I'll repeat that again, today with OUR technology if we wanted to put two space-craft into deep space, it would be possible with 2008 sensor technology to fight at ranges exceeding two thousand miles. With the best super-fast rail gun in existence today at those ranges it would take minutes between firing your unguided projectiles and when you would hit.

And with the best laser we have today how much damage could we do at that range?

Be serious people bullets in space are useless, the ranges are simply to great to make any non-guided or C weapons useful. And FYI if you put little motor's on bullets to make them self guiding guess what? It's a missile now, might as well simply build it as a missile to begin with.

And what about the issues of missiles in space? This all assumes after all his drive can be miniaturized sufficiently, carry sufficient propellant both for the trip and any adjustments in course, and still be cheap enough to be expendable.[/quote]

[Mr Bean]

So lets review, two Appollo space craft armed some-how with rail guns and perfect targeting could not engage each other effectively beyond 5,000 kilometers not because they can't aim well but because even the lowly Apollo can walk out of the way at those ranges. A "advanced" space craft can most likley dodge all the way up to 2,000 kilometers at such ranges. Faster speeds only make things harder since at that speed, while there is less travel time, slowing down or simlpy not thrusting as much randomly makes it very hard to hit you unless you can fire DIRECTLY at them, instead of firing at an angle(however slight) towards them.

Un-powered projectiles are damn worthless in space unless you shooting at something that can't dodge.

Like a planet.

Unless you make the projectiles very fast(IE close to C) and any sufficently powerful system that can launch KKV's at speed close to would be better served being used to power a laser, a laser which starts out as fast as it gets to begin with as noted unlike a rail-gun which would have issues at 5,000 kilometers a Laser is still-instant hit all the way up to 100,000 kilometers.

[Junghalli]

That assumes you don't use multi-stage rockets, they won't slow down after all. You kick in a main stage with a powerful booster to get the KPS up as high as possible with a smaller more fiddly engine with better handling abilities once it gets X miles away.

The problem isn't getting the missile up to speed. The problem is that the kind of drives a fast spacecraft is likely to use just don't scale down well; you're unlikely to be able to fit one in a missile and have something small enough that a warship can carry the hundreds of missiles needed to get past enemy point defense. So you'll end up using less fuel efficient (probably chemical) drives for the missiles, which means your range is limited by the point where your missile can't out-accelerate the enemy and have enough delta V left over to compensate for his evasive manuevers through the whole trip.

Also as noted you have the possibility of putting mass drivers in your ships to give the missiles a high initial speed the engine will only boost.

Again, the issue is that a fuel-efficient nuclear engine would probably be prohibitively massive. Although giving the missiles a boost would extend their effective range.

*Edit the main issue with missiles is how smart you can make them. After 100k miles your talking about light-speed delays for commands from the base ship.

I don't think that would be a problem. The missile's programming would only need to be something like this: "you see that giant infrared source? Ram it. If it attempts to evade compensate at a slightly higher acceleration." Probably child's play for today's computer technology, let alone centuries more advanced.

[Ender]

I like how we are comparing lasers of today with railguns 4-6 years off and engines that aren't even on the drawing board yet.

[SylasGaunt]

Why not use the systems astroid belt and slap an engine on any handy chunk of rock? It's not like you need to use your own.

How many spare space craft are going to be carrying a spare engine around with them they can afford to slap on an asteroid? And that leaves aside the fact that if the enemy has the same tech level and active ships they can attempt and intercept.

[Darth Wong]

Interesting side-note: if you can force a realistic spacecraft to maneuver too many times and accelerate too quickly, you'll use up so much of its fuel that it cannot complete its mission. In an extreme situation, you could effectively disable a ship by simply forcing it to maneuver enough times, because it will run out of maneuvering fuel (it must have used most of its energy just getting to the point of attack anyway), thus leaving it a helpless drifting mass.

By that same token, planetary attack missions would be one-way missions in a realistic sci-fi setting. There's no way the ships would have enough fuel to fight their way to a target planet and then fail to take it. If they take it, they can use its resources to refuel their ships and build new ones. If they don't, they're fucked. They can't even go back home.

[Ender]

Interesting side-note: if you can force a realistic spacecraft to maneuver too many times and accelerate too quickly, you'll use up so much of its fuel that it cannot complete its mission. In an extreme situation, you could effectively disable a ship by simply forcing it to maneuver enough times, because it will run out of maneuvering fuel (it must have used most of its energy just getting to the point of attack anyway), thus leaving it a helpless drifting mass.

By that same token, planetary attack missions would be one-way missions in a realistic sci-fi setting. There's no way the ships would have enough fuel to fight their way to a target planet and then fail to take it. If they take it, they can use its resources to refuel their ships and build new ones. If they don't, they're fucked. They can't even go back home.

Depends on the engine type. Some kind of AM ramscoop could do it - the mass of fuel reactant relative to fuel is sufficiently small that it can carry enough and the ramscoop could get the fuel to expell.

[SylasGaunt]

Starting to get a grasp of how hard it is to hit a ship that's has ANY ability to dodge at those ranges?

Yes but when has anyone been suggesting that any of these ships are going to be engaging at those ranges? Again you seem to be working under the assumption I am saying a projectile will have an easier time hitting things at extreme ranges than a laser.

Of course why you seem to be assuming the railguns would possess a uselessly low velocity and all fights will take place at stupendous ranges while the lasers apparently won't suffer any problems at all from diffraction is a mystery.

Then there's still the issue of bracketing fire to prevent the enemy from shifting position.

[Junghalli]

With a good inertial confinement fusion drive, like Project Daedalus would use, you could get to Saturn and back in a little over a month, with a spacecraft that's 40% fuel by mass.

I don't think being able to do a two-way mission is neccessarily impractical.

[Ender]

With a good inertial confinement fusion drive, like Project Daedalus would use, you could get to Saturn and back in a little over a month, with a spacecraft that's 40% fuel by mass.

I don't think being able to do a two-way mission is neccessarily impractical.

Realistically, yeah it probably is. All the serious talk of interstellar travel has slowly shifted to externally powered interstellar ships since the early-mid 90s when Zubrin published about the ramscoop and Francis started talking about particle beam engines. Now most of the really serious stuff I've seen for moving anything more then a handful of people looks at externally powered stuff. However, we are granting tech that allows for war here, so in that scenario I don't think granting ramscoops, Valkerye, or AIMStar to work is out of line.

[Ender]

It occurs to me that nay really serious invasion would include with it some kind of logistics ship. Something that would let them make things on site rather then shipping guns and tanks between the stars. Attaching a few hoses, pumps and compressors wouldn't be tough, drop it off at a gas giant on your way in, and return to it to refuel later if you need to retreat.

[Themightytom]

Interesting side-note: if you can force a realistic spacecraft to maneuver too many times and accelerate too quickly, you'll use up so much of its fuel that it cannot complete its mission. In an extreme situation, you could effectively disable a ship by simply forcing it to maneuver enough times, because it will run out of maneuvering fuel (it must have used most of its energy just getting to the point of attack anyway), thus leaving it a helpless drifting mass.

By that same token, planetary attack missions would be one-way missions in a realistic sci-fi setting. There's no way the ships would have enough fuel to fight their way to a target planet and then fail to take it. If they take it, they can use its resources to refuel their ships and build new ones. If they don't, they're fucked. They can't even go back home.

I feel like that would actually MAKE an awesome story,

[Junghalli]

Realistically, yeah it probably is. All the serious talk of interstellar travel has slowly shifted to externally powered interstellar ships since the early-mid 90s when Zubrin published about the ramscoop and Francis started talking about particle beam engines. Now most of the really serious stuff I've seen for moving anything more then a handful of people looks at externally powered stuff.

I wasn't talking about interstellar voyages, just interplanetary. I base this on the impression that Knife's universe uses a set-up sort of like hyperspace-era Known Space: you have rockets for getting around solar systems and some kind of handwavium FTL method for between them. In which case for purposes of delta V calculations you can basically treat the whole universe as one solar system, more or less, depending on whether there's a "hyperlimit" you have to get outside of and where it is. The OP creator can correct this if I am wrong.

BTW you could do a return mission with a laser lightsail, but I doubt this would be very viable for a military mission. Way too easy for the enemy to just blow up the vulnerable sail stages.

[Sea Skimmer]

Interesting side-note: if you can force a realistic spacecraft to maneuver too many times and accelerate too quickly, you'll use up so much of its fuel that it cannot complete its mission.

That’s a major factor for real life air defenses. Simply by firing on an enemy you can often force him to jettison drop tanks and bombs to maneuver to escape.

By that same token, planetary attack missions would be one-way missions in a realistic sci-fi setting. There's no way the ships would have enough fuel to fight their way to a target planet and then fail to take it. If they take it, they can use its resources to refuel their ships and build new ones. If they don't, they're fucked. They can't even go back home.

That depends on what you need as fuel and propellant. If you only need hydrogen for example you might well be able to find a source in the system. Bringing along a means of fuel extraction seems just logical for the massively logistical effort involved in attacking and invading a planet. The USN built whole floating naval repair bases and supply depots to accompany its advance across the Pacific in WW2.

You’d have to be strong enough to defend yourself against counter attacks while you gather up that fuel, but you figure, even if you did fail to take a planet you probably would have still inflicted massive damage, leaving the enemy in a poor state to counter attack.

[Knife]

By that same token, planetary attack missions would be one-way missions in a realistic sci-fi setting. There's no way the ships would have enough fuel to fight their way to a target planet and then fail to take it. If they take it, they can use its resources to refuel their ships and build new ones. If they don't, they're fucked. They can't even go back home.

'Twas pretty much what I was thinking. Each 'assault ship' would pretty much have what it took for a round trip and that's it. Assaults are massive undertakings with millions of personnel and thousands of ships.

[Ariphaos]

Outside of an incredibly dense asteroid field of some sort (Saturn's B ring, possibly) or near an atmosphere, projectile weapons are only useful against nearly immobile targets in a hard sci-fi setting, and their worth becomes somewhat dubious even then.

There's a limit to how fast a coilgun can accelerate a projectile (still trying to work through Kuroneko's math on that when I get the time...), and eventually all of your tricks making railguns and chemical explosives work reaches a limit - the prospect of actually taking a planet in a system that controls the resources of its star is pretty daunting. Without some form of serious magitech or free-range FTL (a la Star Trek or Star Wars), it's nearly impossible.

[Minischoles]

By that same token, planetary attack missions would be one-way missions in a realistic sci-fi setting. There's no way the ships would have enough fuel to fight their way to a target planet and then fail to take it. If they take it, they can use its resources to refuel their ships and build new ones. If they don't, they're fucked. They can't even go back home.

'Twas pretty much what I was thinking. Each 'assault ship' would pretty much have what it took for a round trip and that's it. Assaults are massive undertakings with millions of personnel and thousands of ships.

Even if they are only an assault force you've got to assume they'd bring some kind of logisitical support along as well, carrying spare parts for the ships (even if the ships are near perfectly engineered odds are they're going to need spares at some point), a resupply of ammo and fuel, perhaps even a giant extraction/refinery ship if they do need more fuel, and a factory ship as well (i'm assuming if its a race advanced enough to build spaceships they're at least up to mounting asteroid capture missions for clean resources) that can manufacture basic parts and weapons.

[MichaelFerrariF1]

What are the limits on your FTL? Can you revert to sublight in orbit over the target planet, or do you have to revert outside the system and slowly make your way to the target?

It seems to me that that determines your combat range. If you can emerge in orbit over the planet, combat will probably take place at ranges of hundreds of kilometers or less. If not, you can expect extreme long range combat as defending fleets try to stop your invasion.

[Darth Wong]

The ability to bring along logistical support only increases your non-fuel mass, thus creating more problems. Now in theory, it means you can fabricate more stuff if you need it, but it's a matter of time. Loitering in an enemy star system means that you're in a race to replenish your supplies and rebuild equipment before your enemy can, and he has the planet. He has the established infrastructure. Unless you absolutely smash his infrastructure, he should be able to build more missiles, more weapons, more ships, and supply more fuel much faster than you can.

In a realistic sci-fi universe, you don't really get two kicks at the can. Your mission either succeeds, or it fails.

[Junghalli]

I'm going to give a brief critique of some of your essay's points here...

No problem, I appreciate constructive criticism, and it may be helpful to others.

First, you immediately say that stealth is impossible, therefore suprise attack is impossible. But, you didn't define the setting entirely. If you have a setting like my own where most the action takes place in Earth orbit, the rules change a little. In fact, they change a lot.

Stealth isn't really possible still, but surprise attacks certainly are - everyone is within everyone else's firing range, so all you have to do is hit the trigger. You can also possibly build ships in secret, entirely inside habitats. Someone following the money would probably put it together, but it would take accountant spies (or maybe traditional human spies on the inside) rather than telescopes to figure it out.

No disagreement here.

Kinetics at a range like this would be less useful, since most everyone are barely moving relative to everyone else.

Possibly, though you don't really need to be moving very fast for kinetics to be effective. Anything going at 3 km/s packs the equivalent energy of its own weight in TNT. I doubt many realistic ships are going to like being hit by something sizable going at, say, 8-10 km/s. Moreover, if the ships are only designed to putter around in Earth orbit they probably won't have much more delta V than the missiles, which eliminates one of the main disadvantages of missiles (unless you can put a high-performance nuclear rocket in one they will have a limited range beyond which the enemy ship can just get out of the way). On the other hand orbit would probably be a very hostile environment for missiles, because a missile moving at only a few km/s is a very easy target for a nearby laser. Orbit would likely be an arena in which lasers dominate.

You mentioned the difficulty of matching speeds to make dogfights not happen, but this also expands to something else: your ships don't have much of an option to go off course. Suddenly aborting an interplanetary mission may be impossible; once you go, you're going all the way.

Quite true. If possible I think you would give warships, at least, enough fuel for a two-way mission, probably with some extra for manuevering. But how feasible this is depends on what sort of drive and what sort of transfer orbit you're using.

In earth orbit, your high delta-v engine will never achieve its max speed; the distance is simply too short to let it run. Here, high acceleration is probably optimal; the d-v you need is pretty small anyway, so trading it off for acceleration is probably a reasonable deal. On the other hand, like I said above, if you weapons tech is good enough, everyone is in everyone else's firing range anyway, which makes acceleration go back to being less important.

Agree with this.

It still could be for civilian transit though.

Indeed. I think passenger spacecraft, for instance, will probably use chemical rockets rather than electrical ones, because nobody wants to wait a month to go from LEO to GEO. Of course, I think in a well-developed orbital infrastructure most shipping will be done through a rocketless "highway" system of rotorvators and space elevators.

You said the max range of lasers is about one light second due to targetting concerns. This depends on the size (and acceleration) of the target's side that is facing you - you might be able to hit a 200 meter wide battleship from farther out than a 10 meter wide scout. The solar panels I love would be prime targets if you see them on the wide side, even from a long distance.

True, it's more of a rule of thumb than anything else.

On defense, again, that depends on your setting. If you are in Earth orbit, there is no need for the magic fusion torch, so not all ships need to be WMDs.

Nuclear salt water rockets, D-He3 fusion, and ICF fusion are actually pretty hardish drive systems, I'm not sure if I'd call them magic. But yes, if you're only moving around the vicinity of a planet yes, you don't need such advanced drive systems, chemical, electrical, solar thermal etc. will be used. That said a massive object hitting a city at orbital velocity could still be fairly nasty, though most spacecraft would probably end up breaking apart on the way down and not doing much damage.

Even interplanetary doesn't if you use things like laser stations to move ships around. The ships themselves are just boxes on mirrors - they are propelled by lasers at controlled facilities. Of course, these lasers can also make potential interplanetary death beams...

Oh yes, the simple fact is moving a massive object between planets in a short timescale involves harnessing quantities of energy that would do very nasty things if used as a weapon. Jon's Law.

All in all, I thought it was a good essay, but some of your setting assumptions weren't as clear as they probably should be.

Thank you, and yes I admit it could have discussed a wider variety of scenarios. I was actually planning on doing sections on planetary invasions and interstellar warfare with no FTL, but I thought the thing was getting too damn long already.

[Ender]

The ability to bring along logistical support only increases your non-fuel mass, thus creating more problems.

The thought was that the logistics ship would be a separate vessel. That makes it no more challenging then creating a war ship as your design replaces missiles, armor, and guns with machine shops. You also will do less maneuvering, have less a need to accelerate at a higher rate, etc. Really, without knowing more specifics you can't say which would entail more design problems. In fact if you take the position of being totally from scratch the logistics ship would be easier because you will have already designed most of its machinery and stuff when you were building the infrastructure that let you build the warships in the first place and can recycle the designs, whereas you need to design the weapons systems anew.

Heck, the logistics ship would be easier to design then the ships that carry enough to let you invade in one go for the very reason you cite. I can move a 100,000 ton factory ship and make unlimited tanks, or bring 10,000 tanks for the invasion and have the same design issues. If you want to argue that you can transport the tanks in smaller groups then there is no reason you can't bring the logistics depot in parts as well - we did it with the ISS after all.

Now in theory, it means you can fabricate more stuff if you need it, but it's a matter of time. Loitering in an enemy star system means that you're in a race to replenish your supplies and rebuild equipment before your enemy can, and he has the planet. He has the established infrastructure. Unless you absolutely smash his infrastructure, he should be able to build more missiles, more weapons, more ships, and supply more fuel much faster than you can.

He is welcome to the planet, I'll take the rest of the system. I can always get the planet at my leisure so long as I control the rest. It represents more resources, more power, more space, and more options.

Of course if you are willing to commit what would likely be defined as war crimes there would be no need for the logistics ship. Shoot the orbital infrastructure with a charged particle beam or a dispersed x-ray or gamma laser and kill everyone on board, send in your own robots to operate the space infrastructure there.

In a realistic sci-fi universe, you don't really get two kicks at the can. Your mission either succeeds, or it fails.

How hard do you want to go here? If we assume an absolute hard scifi there isn't going to be much in the way of interstellar war, the distances make it impractical. A book idea of mine is the only way you would see what we recognize as war today - two planets tried to colonize the same system, and one got there before the other. In that case both would be coming with infrastructure to build things on their slowboats, and that is how the war would come about. Other then that it is basically genocide the natives or assimilate the invaders.

[Sea Skimmer]

The ability to bring along logistical support only increases your non-fuel mass, thus creating more problems.

Your invading a planet. Logistical support will be massive or else you’d be idiotic to even think about trying. Establishing some kind of advanced base, even if it doesn’t try to make fuel, will be essential to success just as it was in the Pacific War. You would easily have 3-5 support ships, many of which would simply be conversions of civilian vessels, for every significant warship. Seriously now, in WW2 a destroyer steaming at economical speed could still barely cross the Pacific one way, and merchant ships took several months to do so, but we still managed to support a fleet steaming at high speed off Japan. By mid 1944 the USNs service force ships (these are the ships which directly replenished naval units underway, and at the most advanced of bases) numbered more then 450 major vessels. A couple thousand more ships sailed from the US west coast to replenish the service force.

A single fast carrier task group with 3-6 carriers would have as many as two dozen oil and AVGAS tankers in direct support, plus another dozen ammunition ships, provision ships, hospital ships and general cargo vessels. Dozens of escort carriers did nothing but ferry planes out to replace of losses on the fleet carriers.

No one before or since has matched this massive seaborne supply chain, but its what you’d need for interplanetary warfare. If you can’t mount that kind of effort, and your enemy can’t either to come attack you then you’d have little reason to even try to fight a war.

Now in theory, it means you can fabricate more stuff if you need it, but it's a matter of time. Loitering in an enemy star system means that you're in a race to replenish your supplies and rebuild equipment before your enemy can, and he has the planet. He has the established infrastructure. Unless you absolutely smash his infrastructure, he should be able to build more missiles, more weapons, more ships, and supply more fuel much faster than you can.

That assumes the enemy planet is actually able to build advanced weapons, most targets would be lightly developed owing to the massive effort required to actually invade and occupy a highly developed world. Centers of strong resistance would be bypassed, or simply bombarded from orbit, ground based weapons will never be able to compete with orbital weapons in the absence of some kind of energy shield. If you can even think about attacking a planet with say the development of modern earth then your resources should be so overwhelming that sending out fuel tankers is no big deal.

Anyway, if you cant mount the proper logistical effort to attack another planet, then why even try? The enemy probably cant attack you either, and its pointless fighting over the mere void of space. A truly realistic space war would probably last for decades with a battle between tiny unmanned patrol vessels every five years or so.

[Alyrium Denryle]

By that same token, planetary attack missions would be one-way missions in a realistic sci-fi setting. There's no way the ships would have enough fuel to fight their way to a target planet and then fail to take it. If they take it, they can use its resources to refuel their ships and build new ones. If they don't, they're fucked. They can't even go back home.

'Twas pretty much what I was thinking. Each 'assault ship' would pretty much have what it took for a round trip and that's it. Assaults are massive undertakings with millions of personnel and thousands of ships.

If that is the case then static planetary defense systems become a workable solution. Armed satellites could, in theory, fire off enough missiles, that would force ships to either maneuver (thus using fuel) or be destroyed. At the very least it would increase the costs of undertaking an invasion, and increase the vulnerability of the logistics train to pre-assault counterattack.

As for ship to ship combat and weaponss, I am rather fond of Coyotes idea, to use solar collectors to power weapons. Also bear in mind, that without handwavium FTL sensors, ships will be restricted to various types of light collection. Light Telescopes, IR, Radio, and Gamma wave sensors would be how ships are detected, making stealth, in addition to maneuver and power use very important.

One thing fleet ships (destroyers and the like) would want to do in combat is keep the solar collectors to one side (toward the local star) to avoid them being shot off, while also keeping themselves from being detected, and keep themselves in a good firing position.

Were you to write out combat, fleet captains would be playing a very dangerous, and if written correctly, interesting game. And also bear in mind, a planet's defensive fleet would have to be taken out, or you risk your logistics train during a planetary invasion and would be forced to withdraw.