7
$\begingroup$

Maneouvrability is a potentially significant advantage in almost any battle. But, the maneouvrability of a spacecraft with inhabitants is limited by the inhabitants's tolerance to accelerational forces. Humans generally can't tolerate high g-forces for a long time. Even to horizontal g-forces, which are more tolerable than vertical g-forces, untrained humans can tolerate 20 g for less than 10 seconds, to 10 g for 1 minute, and 6 g for 10 minutes (Source : Wikipedia). The limits for trained humans may be higher, but not much higher.

Considering that, I put forth a system, where most battleships are remotely controlled from specialised control ships, where the crew are. A crew member sits in front of a computer, controlling what he is in charge of. He sees what he needs to see, and not too much else (e.g. a gunner sees his field of fire, whereas the admiral sees the entire battlefield).

Obviously, in such a system, the most valuable targets would be the control ships, much like the generals were in historical battles. The loss of a control ship means that all the ships controlled from it lose some degree of control (not necessarily all control, since the other control ships can take it over; but they only have basic control such as "move there", "fire the forward guns", "self-destruct", etc.). The loss of all control ships means that the battle is lost. Because of that, control ships are generally the most well-shielded.

Details on FTL travel:

  • Ships can travel to the battle site faster than light but can only battle at subluminal speeds.

  • Faster-than-light travel is done through "hyperspace" and has a 15 minute recharge time, ship time (after emerging from hyperspace, ships need 15 minutes before being able to activate FTL again)

  • FTL travel speeds vary from 10,000 to 40,000 times the speed of light, with the average being 20,000 c.

  • A ship retains its direction of movement when entering hyperspace, and upon leaving hyperspace its speed reverts to the speed before the FTL travel. For example, if a ship travels at 0.001 c and enters the hyperspace, upon leaving it its speed would be 0.001 c. Corollary : If a battleship were to travel FTL in a direction it's not heading towards, it either uses the subluminal propulsion system to adjust its direction then actiivate FTL, or activate FTL first, emerge in a relatively safe location, adjust its direction while waiting the 15 minutes, and activate FTL.

  • A control ship can travel FTL, but if it's not travelling FTL, its acceleration is limited by the crew's tolerance.

  • FTL communication without FTL travel is available, but the transmission and reception facilities needed is too large to be put in a ship. Such faclities are generally built on planets. Therefore, ships in a battlefield communicate at no more than c.

Details on combat capabilities:

  • Ships only battle (fire guns, launch fighters, etc.) at subluminal speeds. Guns can be fired in hyperspace, but why waste ammunition?

  • Battles are conducted at a range of about 1,000 km ("close quarters") to 300,000 km ("long range").

  • Battleships and control ships have shields; shields deplete as energy (including kinetic energy but not including the $E=mc^2$ mass-energy) is thrown to it.

  • Shields stop only incoming projectiles etc.; shots from inside are practically unaffected.

  • A ship generally can take 20,000 hits from "standard-issue" guns (which are the most numerous of the guns), a large battleship can take 30,000, a control ship can take 40,000. Missiles are about 10 times more effective, but 20 times fewer. Battleship main armaments can take down a control ship with only 40 hits. A control ship can usually be destroyed with a 200 MT of TNT weapon.

  • Most of the weapons used are subluminal; projectiles travel at around 20,000 m/s.

My question:

How far from the other ships would the control ships be located? What distance is a good compromise between response time and safety?

Edits:

  • The ships travel as fast as needed (and tolerable, for control ships). Remember, this is space, there's no atmosphere to slow you down. So acceleration is more important. Control ships are usually capped at 1 g, but can accelerate to 6 g for a short time. Other ships can reach 100 g on average, with the range being 40 g (heavy battleships) to 250 g (fast, small ships). Fighters can reach 400 g.

  • Control ships are about 750 m long, heavy battleships 1,500 m to 2,000 m, fast cruisers 500 m.

  • Let's say communications technology has developed to the point the equipment is resistant to being disabled, and that communications can't be intercepted nor faked (one side can't control an enemy ship).

  • You can't just disguise a control ship as a controlled ship; sensors are available which can detect shield strength.

  • A shield extends to hyperspace forming an "umbrella". Trying to emerge on or near a shielded ship results in prompt, utter destruction of the attacking ship, and little damage to the attacked ship almost regardless of the previous speed of the attacker. (But yes, if the ship's shield is down, an FTL attack can take down the ship.) The umbrella is about 15-20 km in diameter.

  • If a fighter starts from zero speed and uses all its fuel to accelerate in a straight line, it can reach 5 MT of TNT equivalent.

  • Fighters can't travel FTL. The smallest ships which can are about 300 m in length.

  • Each crew computer has a toggle for "automatic mode", in which it takes general orders (such as "fire at that ship every 10 seconds") and executes them automatically. But, the operator can override it or disable it altogether.

$\endgroup$
  • 1
    $\begingroup$ Nice question. What speeds are fighters and other ships typically traveling at during a battle? Also, I'm guessing that you don't have to destroy a control ship to make it useless; you just need to disable its communication systems. Oh, and how large are the various ships? $\endgroup$ – HDE 226868 Jan 14 '18 at 15:36
  • $\begingroup$ Since everything takes place in inertial space, a one light second distance (roughly the distance from the Earth to the Moon) provides a good compromise between response and safety. However, since most realistic space weaponry will be capable of firing effectively to one light second, you now have at least a 2 second delay built into the loop (i.e one second to locate the target and one second to relay this back to the control ship). Given processing time to understand what you are seeing and send orders, you could have a 5+ second delay between sensing and shooting. $\endgroup$ – Thucydides Jan 14 '18 at 15:37
  • 1
    $\begingroup$ @Thucydides You can write a full-fledged answer if you want. $\endgroup$ – user_194421 Jan 14 '18 at 15:44
  • 1
    $\begingroup$ Have you figured out why the ships don't fight independently? Fully AI controlled spaceships seem easier to build than FTL propulsion. $\endgroup$ – Erik Jan 14 '18 at 19:39
  • 1
    $\begingroup$ You do realise that your projectiles would take 50 seconds to reach "close quarter" target or 4 hours and 10 minutes to reach "long range" target? Assuming stand-off with 0-relative velocity, anything further away than 18000km can recharge FTL before any incoming fire reaches it. With 40g acceleration, in 50 seconds, heavy BB can reach any point within 500km of point of origin. Assuming they are 2km*2km you need 200.000 shots to guarantee >>1<< hit. For long range it's 44000000km and 1.520.000.000.000.000 shots for >>1<< guaranteed hit. I don't think you thought your numbers through. $\endgroup$ – M i ech Jan 15 '18 at 11:09
6
$\begingroup$

Time

Light travels at 300,000 km/s. In the largest battles, you'd want to station your control ships on the edge of the fighting. Let's say that each one is responsible for controlling ships in a sphere with radius 150,000 km. This means that if a fighter detects something and needs to avoid it, it has to send a signal to the control ship (which will take half a second). Someone on that ship needs to make a decision; let's say they make an evasive maneuver within one second. The signal then takes a half second to travel back to the fighter.

This adds an extra second - which can be critical with projectiles and ships traveling so fast. You said projectiles can travel at 20 km/s; if a ship can send a guided missile of sorts at that speed from 10 km away, it will hit the target in half a second - and the control ship won't have been able to do anything. Most shots will likely be fired at closer ranges, which gives even less time to react. That's also bad enough, but having a control ship half a light-second away makes thinks worse.

You need to reduce the distance of the control ships drastically. Ideally, transmission should happen both ways in less than half a second, maybe less. So that puts you maybe four times closer to the ships - and also puts you in range of enemy attackers. I would say that, in terms of timing alone, you'd want to be less than 40,000 km away from the section of the battle you're controlling.

How to attack a control ship

Say an enemy fighter can travel, in battle, at a kilometer each second. That means that it would take 40,000 seconds traveling at that speed to reach the control ship, from the thick of the fighting. That is, give or take, half a day. Even if you increase this by a factor of ten, it would take an hour. That's not feasible. You'd be detected long in advance and destroyed with ease. You can't surprise the control ships.

The alternative? Jump through hyperspace. On an attack run, a fighter picks up speed, then jumps to about 10 km away from a control ship. If their pre-jump speed was 1 km/s, they've got 10 seconds to start their attack, and the control ship has 10 seconds to respond. If the fighter does things just right, and aims properly, they'll be able to get in a strafing run or two.

A big problem could be suicide attacks. Increase your speed to 10 km/s pre-jump and aim just for the center of the control ship, the bridge, the engines, or the communications structures. Assuming you did it right, you'll hit your target in 1 second, and the control ship won't have time to move away.

So, how do you guard against these? I don't have great ideas here. You could have the control ship be constantly moving, but it can't turn too quickly - it's got humans aboard! It's defending against an attacker that has the ultimate element of surprise, and can be there in an instant, once the shields are knocked down.

So here's the problem: The enemy will always bring the battle to the control ship. They might try an attack plan like the following:

  • If there's a different primary attack target - a flagship, a moon base, a space station - send one quarter of the fleet to that target.
  • Send another quarter of the fleet to attack the control ship and bring down the shields.
  • Once the shields are down, use data from the ships already there to let the other half of the fleet know the control ship's position and velocity.
  • Take it down via suicide attacks (or by jumping to hyperspace and launching a missile when the attackers come out).

Mitigation

Like I said before, you can't guard against this sort of a strategy too well. You have to hope you can keep your shields up long enough to fend off the attackers (or if the control ships are on the offensive, hit your targets). Now, I said I didn't have great ideas about how to fight this. But I have a couple:

  • Use redundancy. Have each fighter be able to be controlled by two control ships. One control ship will take on additional fighters if another is hit.
  • Jump to hyperspace. You can do this once every 15 minutes. In a pinch, do this as a last resort . . . assuming you can't be tracked this way.
  • Give the fighters some AI. This is a good option, if you have the tech. It can have basic functions - evasive actions, some weaponry control, etc. Also, you could have intermediate-level ships have the ability to command fighters in the near vicinity.

A note on communications structures

Every large enough sci-fi vessel has some sort of vulnerability, buried deep down (according to tropes, at least). Barring that, there's some critical part of its infrastructure that needs to be protected. For the Death Star, it was a womp-rat sized target in a trench; for the second Death Star, it was the shield generator on a moon below.

The thing is, you don't need to destroy a control ship entirely. You just need to knock out its communications arrays. It doesn't matter if it still has weapons or fighters; it can't control the rest of the fleet if it can't transmit data. This means you need additional layers of shielding, just for those sections. The alternative to shielding, of course, is to remove the control ship far from the battle. But as I wrote before, that makes it ineffective.

$\endgroup$
  • $\begingroup$ 1 km/s might be quite low for space battle, as you'd need 8 km/s to stay on Earth's orbit. The distance to control ship might be greatly increased if FTL communication is viable. If not: send FTL messenger bots! $\endgroup$ – Oleg Lobachev Jan 14 '18 at 17:05
  • 1
    $\begingroup$ @OlegLobachev I'm talking about relative speeds here - and, in general, battles farther from planets. So when I say 1 km/s, I mean relative to a local orbital frame. Also, yes, FTL communication is a good idea, but it would necessitate a lot of bots, which could get shot down or destroyed pretty quickly if they only had minimal shielding, $\endgroup$ – HDE 226868 Jan 14 '18 at 17:08
6
$\begingroup$

How far from the other ships would the control ships be located? What distance is a good compromise between response time and safety?

@HDE 226868 is right: if they can, the enemy will always bring the battle to the control ship. A control ship close enough for effective realtime subluminal communication will be quickly detected and hit by remotely controlled attacks jumping FTL to the site of the control ship. Not really suicide attacks if they are remote controlled.

Side note: subluminal communication is presumably electromagnetic lightspeed radiation of some sort. This cannot be faked (per OP) but can be easily interfered with by massive noise generators. Although that would cut both ways.

My proposition: Pony Express.

Your FTL communication requires stuff too big to put on ships. But your ships can go FTL. If vehicles can move faster than light, send your communications on the vehicles. A relay of small jumping vessels can bring communications near the site of the battle, recharge the FTL and then jump back with fresh updates from the front. Around a battle at any given time would be a large number of droneships (none concentrated in any one spot) which blink into space in the vicinity of the fight and transmit communication to the nearby drone fighters. After recharging they pick up communication from the fighting drones just before blinking back. There would be enough of these to make communication continuous. With more you could also make communication redundant.

With the FTL pony relay, your control ships can be arbitrarily far away. They cannot be traced unless you can track the FTL pony ships somehow when they return.


A seemingly clever trick would be to put a locator beacon on one of the returning ponies and detect its signal when it blinked out of FTL near the command ship. Some slick scifi: the locator beacon is detected and destroyers are sent to the vicinity of the locator beacon. There is nothing there but an long-abandoned planetary base. Someone had come up with the same idea some decades before and when no signal was received from the locator, decided that it did not work. But it did work. Light is just slow.

$\endgroup$
  • 1
    $\begingroup$ Then won't the enemy attack the communications? $\endgroup$ – user_194421 Jan 14 '18 at 22:35
  • $\begingroup$ Oh, and activating FTL conserves your direction, so they know what direction you're jumping. $\endgroup$ – user_194421 Jan 14 '18 at 23:13
  • $\begingroup$ If communications are a fair target then they are at just as much risk coming from a distance than from up close pony ships. But OP says "can't be intercepted or faked". If by attack the communications you mean attack the ponies sure they can do that. They are small and numerous and they unload their message as soon as they appear. Then they wiggle around. Re "conserve your direction"; there is a lot of space in any given direction. This pony scheme would not work if FTL drives are large and expensive but then FTL fighters might not exist either. $\endgroup$ – Willk Jan 15 '18 at 0:59
  • 1
    $\begingroup$ Since "normal space" velocity and direction are preserved on FTL jumps (per "For example, if a ship travels at 0.001 c and enters the hyperspace, upon leaving it its speed would be 0.001 c") - the ponies can be sent at insane speeds, so unless they hit something, they just jump in, transmit payload, and zoom out of the battle zone way before anything can harass them. $\endgroup$ – G0BLiN Sep 4 at 15:29
  • 1
    $\begingroup$ On the other hand - the same may be used for swarms of missiles, appearing at very close range and imparting a lot of kinetic energy to the target or its shields... $\endgroup$ – G0BLiN Sep 4 at 15:31
3
$\begingroup$

I would consider a beacon system, in which a small beacon floats relatively closer to the battle and uses radar cloaking tech to stay out of view. The pilots of starfighters would be stationed here, and the commanding officers would stay on control ships on the outskirts, as they don't require split second reaction time. With the beacons, the starfighter pilots are close to the fighters so the commands take almost no time to transmit.

$\endgroup$
3
$\begingroup$

Since your remote crew essentially operate the ship as though they were there, we can model the effects of round-trip comm latency as an online game. We'll presume open space with noise not a factor, and hardware effects on latency negligible.

Distances are the sum of distance between the command ship to the remote ship and the remote ship to the enemy (due to sensor latency)

1500km: 10ms Latency. Ace range, crews can operate ship as if in person. Human reflex limits are bottleneck. Probably favoured by your ace gunners etc. Weapons within 75secs of command ship.

2795km: Fighter kill range. Assuming a fighter the weight of a space shuttle (~75 metric tonnes) a fighter can accelerate to 105km/s and 200MT of energy within 26.5 seconds and covering this range. Your command ship should probably be able to swat a target moving at speed in a straight line from at least this far.

7500km: 50ms Latency. Optimal range, where most people can react. Past this point performance starts to decline.

15000km: 100ms Latency. Outer limits of FPS play. Maximum range for gunners, past this point fire control needs to be turned over to automatic systems.

18000km: Outer limits of standard weapons. Assuming 20km/s is a limit for relative velocity (ie. Aiming breaks down past here) past this point a ship can hyperspace quicker than weapons can reach it.

75000km: 500ms latency. Outer limits of third person (say, racing) play. Maximum range for pilots, past this point is autopilot land.

150000km: 1000ms latency. Outer limits of RTS play. Maximum range for tactical control, past this point it's likely only broad strategic control will be practical.

This all, of course, goes out the window if c-fractal hyperspace missiles (kamikaze fighters) are in play. I'd suggest tuning the details of your hyperspace system to prevent such a strategy from being effective. (Maybe you crash into the shield from anything more than N seconds away, making point defence easy? Jumps are predictable? Your call)

To answer the question, about 18000km from the battle would be the safe distance, but would be operationally impractical since a closer command ship would have better performance and outfight your fleet.

Optimal engagement range would place the command ships somewhere between 7500-15000km from the 'front'. They would need to manoeuvre somewhat since they're still 'in range' but their attendant fleets would have a significant advantage against an opposing command ship staging a remote attack.

Bomber command ships and other ships commanding vessels with simple fire control may be able to work out to a good 75000km though the bombers would be pretty vulnerable - though effective if the opposing fleet is tied up.

$\endgroup$
0
$\begingroup$

Use AI compounded with remote control.

As said in user_194421's answer, the battle area is generally too large for light-speed communications to be effective at controlling craft, as there will be a noticeable and possibly life-threatening delay.

The solution is to use less commands. With sufficient technology, an AI can be developed that runs the ship (i.e. directly interfaces with maneuvering and weapons systems), but also takes a higher-level objective from control ships. These "objectives" could be like "Kill enemy ships", "Destroy something" or perhaps just "Patrol the area". The delay will not be as critical as all immediate decisions are being executed onboard.

$\endgroup$
0
$\begingroup$

The problem with shields, in this context

You need to reconcile the Star Trek transporter dilemma wherein having shields up prevents certain high density data signal data transfers, such as transporters. At the end of the day, since the field units are limited to non-FTL communications, they are going to be limited to radio signals. They can be encrypted, they can be intercepted, they can be jammed, they can be drowned out by radiation surges or a strong enough magnetic field, like from a planet or sheild generators. So shields up or continue transmitting?

I imagine that a lot of strategy in this universe will revolve around communication drones to help extend your control network and reduce the visibility of your command ship's EM signature, decoy drones that send out a similar EM signature to a transmitting command ship, and signal jamming / electronic warfare. Unfortunately, ECM is going to evolve at the same pace that your communications technology does - and in this kind of strategic paradigm there's a strong incentive for it to evolve faster. It sounds like the best investment a defending planet or space station could make is in high-power jamming in fact.

$\endgroup$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.