Sci-fi Military Tactics and Strategy

The crux of the problem is : the fuel reserves limits the delta-v available to the missile. The duration between detection and impact (or miss) limits the delta-v available to the target. If the missile has more delta-v, it hits ; if the target has more delta-v, it evades.

Now I'm thinking it would be a good idea to shoot the missiles out of a railgun. Free delta-v is always nice. Note also than packing more fuel than should be necessary is good if the missile is a kinetic ; if you don't expend it entirely it still contributes to the damage done.

On the target's side, early detection and tracking of the missiles is crucial. If you only start evading when the missile is halfway to your position, you've lost three-quarters of your response time.

edited 17th Jul '15 7:58:43 AM by Aetol

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Of course, if point defense is strong (at whatever tech level the two sides are using) then evading at all may be a mistake. Save your fuel and rely on your weapons instead.

edited 17th Jul '15 8:03:49 AM by DeMarquis

Lasers offer better range and accuracy than railguns but aren't very efficient or powerful. You might only be able to destroy guidance and control systems rather than destroy it outright. At that point the missile is ballistic and even slight maneuvers would be enough.

On the other hand, a railgun round would turn even a well armored kinetic kill missile to fine powder with a single hit.

How good can point defense be against a kinetic weapon ? If you disable it, it stills hit you (and it's too close, too fast for you to dodge). If you blow it up, you still get a face full of shrapnel. Armor may help against that, but it hurts your maneuvering.

The number one problem I see with lasers is heat. Lasers are inefficient. And radiators can and will be shot off.

And about turning a kinetic kill missile into fine powder... that powder will still have a velocity in the 10⁴ m/s. You don't want to be in the path of that.

(Wait, with all those edits I said the same thing twice.)

edited 17th Jul '15 8:33:55 AM by Aetol

Worldbuilding is fun, writing is a chore

So no matter what you do you're still driving a serpentine and dodging debris.

On the other hand, would it make more sense to rush a missile focused ship while under the cover of point defense or would it be better to wait until a missile carrier is out of ammo to close into railgun range?

Waiting for the missile carrier to run out of ammo means it's free to do whatever it came for. And then it will make a run for it, so your chances of catching it are slim. Not a good tactic.

I'd recommend tossing missiles back, under the cover of defensive ships a few 100 km forward. If it tries to shoot through them, the missile will get disabled/destroyed and you'll have a few seconds to dodge. If it tries to shoot them first, then you have free reins to shoot it unchallenged.

Though if you do manage to get a point-defense ship at "knife-fight" range of an enemy ship, you'd definitely ruin its day. But getting there is tricky.

edited 17th Jul '15 8:45:21 AM by Aetol

Worldbuilding is fun, writing is a chore

I really don't like the idea of only retaliating with missiles alone. If the enemy has the same point defenses you have then it's a stalemate at best.

It occurs to me that the threat of a knife fight might be more effective than an actual knife fight. I could send in a force of point defense ships into the enemy walls (not lines, walls), scattering them as they try to stay out of railgun range. Of course, this force would probably take heavy casualties but it would mean that I can pick off the enemy piecemeal.

edited 17th Jul '15 11:18:54 AM by Belisaurius

Sorry but no, delta-V is important, but even if the ship has 500 m/s^2 total delta-V but can only thrust at 1 m/s^2, then it can still be slagged by a missile with a delta V of 100 m/s^2 sends if it can thrust at 5 m/s^2.

Point defence is not perfect, and a missile doesn't have to carry only an explosive payload, I could easily imagine a large missile carry cluster munitions, solid impactors à la grapeshot, or a bomb-pumped laser.

That's assuming you survive contact with the enemy picket-wall, which will probably be made up of similar sorts of ships. Also, lasers can be used to leave you blind.

edited 17th Jul '15 12:18:31 PM by MattII

If you know a missile is coming at you, I'm thinking that its better to manuver early, forcing the missile to expend its fuel, even if you end up expending your own, because a ships weapons are very likely to be better than the missile, if its even carrying any. There are advantages to being larger.

Yes, if you try to get your point-defense ships in close, you'll have to deal with the enemy's screen of point-defense ships before you can reach his missile carriers. Knife-fight between ships that all excel at close combat ? It's gonna be a massacre.

Though what should evasive maneuvers be, is an interesting question.

If you're the Fragile Speedster type, I think you should try to get away from the missile. Even if the missile out-speeds you, you only need to outrun it until it runs out of fuel ; then you just step out of the way. Though I would rig the missile to explode when that happen, because a big expanding ball of debris is more difficult to dodge than a slug.

If you're more a Mighty Glacier, meaning you can't really avoid being hit but might be able to take it, then you should try to minimize its energy. Evade laterally, so the missile has to turn to follow you and expends its delta-v to change direction instead of increasing its speed. When you're hit, the missile should have expended most of its mass and did not reach a very high speed, so the impact will be minimal.

And then there's the case when the ship won't evade, for example because it's shielding something. For example, a point-defense ship stationed between you and an immobile space station. If you fire a missile at it and it evades, it will leave the station completely undefended. If it doesn't... well, as I said before, point defense don't works really well for yourself.

edited 17th Jul '15 2:13:23 PM by Aetol

Worldbuilding is fun, writing is a chore

A head to head engagement with an enemy picket-wall would be a stalemate at worst. At best, it's a matter of managing engagement times. Get you're ships going at a good clip of say 20 Km/s and assuming that the pickets have a weapons range of 100 Km or so a ship just needs to last 20 seconds. It helps that this tactic forces a large number of ships over a small space. The typical response would be to reform the picket into an envelopment but that still destroys the formation. In order to catch the attacking force the picket line would need to accelerate back towards their own lines. However, this thins the interception zone.

Being blinded with lasers is less of an issue in this case than usually. The ships are close enough to network point defenses together with tight beam comms.

We're talking about ships armed to intercept passerby missiles going much faster. Remember that you're trying to do the exact same thing to the missile carriers, behind. It wouldn't be so much a "stalemate" as "most ships on each side are FUBAR". You'd need numerical superiority to get enough ships through, and even then you're throwing a lot away.

Now, if you can flank the enemy formation^note (No stealth in space, I know. Hide behind the planet you're orbiting or something, be creative.) then you're going to have a field day.

edited 17th Jul '15 2:51:33 PM by Aetol

Worldbuilding is fun, writing is a chore

100 Kilometers!? We were talking about ranges up 100,000 kilometers. That'l take more than 20 seconds to cross. Unless this is taking place in a battle space crowded with civilian ships, like a planetary orbit.

If they then end up in a situation where they will close in 20 seconds, then it becomes a "high-speed pass" sort of battle, like certain high-speed fighters in late WWII. There may actually few casualities on either side in any single pass. If there is a planetary body nearby, the two fleets could swing around and take another swack at each other.

As for the type of manuver to wear down the missile, so that point defenses have an easier time taking it out- that will depend on the relative trajectories when the launch takes place. If the target ship was moving away from the launching ship, then it can do just as you say. But if the two ships were moving toward each other at a relatively fast combined speed, then it may be impossible to get away. A spiral pattern of approach might be the best way to run down the missile's fuel.

edited 17th Jul '15 3:00:47 PM by DeMarquis

@Aetol

Hence a pseudo-wedge formation. If you can't fix and flank you need to pierce the enemy lines. Still, if you succeed you've decamated the enemy's missile ships and if you fail you've exchanged looses with the enemy front line. It's win or draw and I like those odds.

@De Marquis

We're talking railgun focused ship against railgun focused ship combat. 100Km is arguably generous.

edited 17th Jul '15 3:21:57 PM by Belisaurius

Why should battles happen at ranges of 100,000 km ? If this is too far away for any kind of weapon to hit anything, then obviously the fleets will move in to closer ranges before opening fire.

Now, until then I've had imagined mostly static battles, with the missile carriers taking potshots at each other and maybe some point-defense ships trying to get in knife fight range. If the fleets are zipping past each other at high speed in a series of short passes, this changes a lot of thing.

For one, the missiles can use the relative speeds of the ships to do damage. They just needs to maneuver to put itself right in front of their targets — in other words, all the fuel can be dedicated to interception. Evasion will be much more difficult.

Knife fights may or may not happen, depending on whether each fleet is seeking them (putting themselves in the other fleet's path) or avoiding them (moving to the side to avoid getting too close). The damages inflicted on each pass would indeed be less severe than in the previous case, if the speed involved are much higher.

Though I have a question : why would a space battle not happen in the vicinity of a planet (or moon, or Lagrange point) ? Fleets can't really chance upon each other in the immensity of space.

edited 17th Jul '15 3:27:32 PM by Aetol

Worldbuilding is fun, writing is a chore

100,000 km? Space is big. 100,000 km is practically knife-fight range, relative to how big the "battlefield" is.

New Survey coming this weekend!

Exactly. That's less than half the distance to the Moon. Detection isn't a problem even at millions of kilometers. With missiles, distance isn't really a barrier. They cruise until close enough and then engage their engines.

With kinetic munitions (including railguns)? They would work at almost any range provided the enemy being fired at isn't aware- in other words a surprise attack. Otherwise, yes, there's some limit on distance determined by flight time and the amount the target can change course by then (much as Tom and Tuefel have been saying).

Hmm, seems to me that missiles are the only reliable long range weapon in most tactical situations.

Even missiles won't work at very long ranges if the target is aware it's being shot at. You can save fuel by cruising for most of the distance, but that implies the target isn't changing course as soon as you fire the missile.

Surprise attacks can happen at really long ranges. Pitched battles, not so much.

Worldbuilding is fun, writing is a chore

Didnt we just go over all this? It's all down to whichever had the most Delta-V. If it's the missile, it doesnt matter in the slightest when the target detects it, or what manuvers they pull. They better have good point defense, because that missile is going up their butt.

Yes it matters, because the delta-v available to the target is limited by time. The missile's delta-v budget is fixed by the fuel it packs, but the target's delta-v budget increases as you launch your missile from further away. Past a certain range, your missile can't hit, unless it can avoid detection long enough.

edited 17th Jul '15 7:42:09 PM by Aetol

Worldbuilding is fun, writing is a chore

Any missile design of the future is going to hone in on a ship like white on rice. Evasive maneuvers" only works on atmospheric settings.

If it fires, it's going to hit its target unless it's shot out of the metaphorical sky

New Survey coming this weekend!

@Aetol I imagine it's because you're trying to keep a fleet away from a planet or orbital habitat. If you're fighting near a planet the enemy can take shots at you're cities and bases.

@De Marquis

However, a spaceship is inevitably going to have more dV than a missile. Missiles are cheap. They're one shot weapons regardless of how they're used. There's no point putting a high efficiency engine or enough fuel for interplanetary travel. All you need is enough fuel for that initial boost and then course corrections. If you fire far enough out the target could slip out of the missile's engagement envelope entirely by accident making a routine course correction you didn't see coming.

On those really long distances for kinetic or impact oriented weapons. Yeah missiles are pretty much the only option. The number of shots you would need to dump to achieve a meaningful hit on a target with dumb weapons makes it impractical. Sure if they hit they will likely smack the shit out of the target the problem is hitting at those ranges.

I can think of one trick to goose up the velocity of a kinetic impactor but it has two draw backs. A nuclear propelled kinetic impactor as an attack stage. The two draw backs is you don't want this going off anywhere near the parent vessel which is fine since we are talking those really long ranges. The second draw back is once the shot is fired it is pretty much linear. If you are already pushing something 50km/s when this goes off that projectile will be going like a bat out of hell. It will either hit and obliterate the target and itself in the process or it will miss and do it almost in the blink of an eye.

Who watches the watchmen?

That's assuming you know the missile is coming. Also, how do you know that incoming object is a missile and not simply a decoy to let the enemy judge how well you can manoeuvre?

That's all assuming the enemy is willing to take you all out with active defences, rather than just laying a shrapnel minefield and letting you eviscerate your force on it trying to get into close range.

How well do those coms work in the face of enemy jammers?

He's talking strictly about railguns, so a range of 100 km isn't too bad a guess.

The earlier you start manoeuvring however, the less fuel the missile has to use to counter each manoeuvre.

However, if you launch a missile with magnetics (basically a rail-gun writ large), and it coasts in that dramatically reduces the amount of fuel, and makes it difficult for the enemy to track.

A ship has more delta-V, but it can use it much less quickly, which may or may not play a role.

Since a kinetic missile will be nothing more than a powerful engine and big fuel tanks, what would a "decoy" be ?

Not true. The earlier you start maneuvering, the further away you'll get from the missile's initial trajectory. The missile has to match all your accelerations to hit you, regardless of distance. If the missile is coming at you along the X axis and you try to evade by moving at 1 km/s along the Y axis, then the missile must add the same 1 km/s along Y to its velocity to hit you.

So as I said, your missile needs to stay undetected until it's close enough. Basically, the missile's properties (fuel reserves, exhaust velocity, cruise speed...) and the target's maximal acceleration determine a range inside which the missile is all but guaranteed to hit. You do not necessarily need to shoot within this range, as long as you can be sure the missile won't be detected before getting into that range.

edited 18th Jul '15 5:28:48 AM by Aetol

Worldbuilding is fun, writing is a chore