- #1
Jetro
- 18
- 4
TL;DR at bottomIt's a somewhat accepted convention that in realistic scifi space fighters should be impossible to use effectively. In general they are regarded as being easy targets that, at interstellar ranges would be unable to survive in a battlefield that employs current plausible scifi weaponry such as laser and railguns. At a glance this would seem like a reasonable assumption. Lasers travel at light speed and would only have to point at the target and at shorter distances rail projectiles move fast enough that dodging becomes impossible. But is that all there is to it? I'd take the unpopular opinion that the picture of warfare for a fighter/drone wouldn't be as bleak and clear cut as the raw science makes it seem once you start considering the realities of how those kinds of weapons might perform in real world conditions. I'd even go so far as to say that fighters/drones might actually be vital in scifi settings that are trying to accurately portray space warfare. Here's my reasoning.
The target is very small. Your gun is very big.
In Future War Stories, the author cites that a fighter craft at a range of ~239,000mi would have about 2.5 seconds to dodge an incoming laser. As such it wouldn't have enough time to evade enough shots to make it closer to a target. I think there's two problems with this suggestion. Firstly, the laser that's firing can only determine a shot based on trajectories that are 2.5 seconds old. If the fighter is always altering it's course this estimate will always be wrong and it will take 5 seconds for the firing computer to even confirm whether or not it made a hit to update it's firing solutions and try again.
Secondly, even if the fighter were traveling is a predictable straight line, would the computer be able to hit it anyways? That might seem like a simple yes, but it really isn't once you consider how far away such a small target actually is. So a laser fires at a fighter 3 yards tall 239,000mi away. Let's make it easy and say the fighter is traveling upwards at 90 degrees to the laser so the computer can use really simple trig. The fighter is also moving really slow, only 1.2m/s relative to the laser. The laser is In order for that laser to hit the target, it needs to adjust the firing mechanism on it's laser by 4X10^-7 degrees or 4 ten millionths of one degree. If the laser were 10 meters long, it would have to raise it's barrel by 4.5 x 10^-11 or 4.5 hundred trillionths of a mile, which I'm not going to covert, but it's smaller than a picometer adjustment. And that's only for adjust aim up/down.
And that's the main problem. At those ranges, the projectile isn't the limiting factor, it's the weapon firing it. At a certain point you can't make the weapon anymore precise. Even if it can adjust it's aim to ten thousandths of a degree couldn't be expected to hit a target at those ranges, even if the target was standing still relative to the gun. It doesn't matter how precise the targeting computer is at calculating since the gun will be limited by physics.
So then we have to ask, at what ranges could a large laser be expected to hit a target reliably. So let's assume it's 10 meters long, and can adjust by as little as 1/10,000 of a degree/second. At 20,000 miles which Future War Stories cited as a realistic engagement range for fighters, the gun needs to adjust by 5 millionths of one degree. Still too inaccurate.
Let's try 5,000 miles. You need to adjust by 2 hundred-thousandth of a degree.
500 miles. You're right about there at 2 ten-thousandths of a degree.
TL:DR With an incredibly ridiculously precise laser gun, firing at the easiest moving target imaginable without account for other issues, like ship vibrations, thermal expansion of the the weapon, the presence of a gravity well, and no third dimension you'd only have an effective range of ~5,000 miles. This would give fighter/drones armed with missiles a very distinct advantage as they could close distances with a larger ship from a variety of angles and fire a very large number of missiles that the targeting computer would have to deal with in addition to the fighters themselves.
And to be frank I wouldn't really expect any weapon large enough to shoot down a fighter to be reasonably expected to have more than 1/100th a degree of precision at the very most, which is just 9 miles effective range. If you can only get one-tenth a degree of precision for the weapon, you'll be able to see Luke Skywalker in his cockpit at less than a mile. At one degree of precision, an A-Wing may crash into your bridge, since your effective range is now 4700 feet.
The target is very small. Your gun is very big.
In Future War Stories, the author cites that a fighter craft at a range of ~239,000mi would have about 2.5 seconds to dodge an incoming laser. As such it wouldn't have enough time to evade enough shots to make it closer to a target. I think there's two problems with this suggestion. Firstly, the laser that's firing can only determine a shot based on trajectories that are 2.5 seconds old. If the fighter is always altering it's course this estimate will always be wrong and it will take 5 seconds for the firing computer to even confirm whether or not it made a hit to update it's firing solutions and try again.
Secondly, even if the fighter were traveling is a predictable straight line, would the computer be able to hit it anyways? That might seem like a simple yes, but it really isn't once you consider how far away such a small target actually is. So a laser fires at a fighter 3 yards tall 239,000mi away. Let's make it easy and say the fighter is traveling upwards at 90 degrees to the laser so the computer can use really simple trig. The fighter is also moving really slow, only 1.2m/s relative to the laser. The laser is In order for that laser to hit the target, it needs to adjust the firing mechanism on it's laser by 4X10^-7 degrees or 4 ten millionths of one degree. If the laser were 10 meters long, it would have to raise it's barrel by 4.5 x 10^-11 or 4.5 hundred trillionths of a mile, which I'm not going to covert, but it's smaller than a picometer adjustment. And that's only for adjust aim up/down.
And that's the main problem. At those ranges, the projectile isn't the limiting factor, it's the weapon firing it. At a certain point you can't make the weapon anymore precise. Even if it can adjust it's aim to ten thousandths of a degree couldn't be expected to hit a target at those ranges, even if the target was standing still relative to the gun. It doesn't matter how precise the targeting computer is at calculating since the gun will be limited by physics.
So then we have to ask, at what ranges could a large laser be expected to hit a target reliably. So let's assume it's 10 meters long, and can adjust by as little as 1/10,000 of a degree/second. At 20,000 miles which Future War Stories cited as a realistic engagement range for fighters, the gun needs to adjust by 5 millionths of one degree. Still too inaccurate.
Let's try 5,000 miles. You need to adjust by 2 hundred-thousandth of a degree.
500 miles. You're right about there at 2 ten-thousandths of a degree.
TL:DR With an incredibly ridiculously precise laser gun, firing at the easiest moving target imaginable without account for other issues, like ship vibrations, thermal expansion of the the weapon, the presence of a gravity well, and no third dimension you'd only have an effective range of ~5,000 miles. This would give fighter/drones armed with missiles a very distinct advantage as they could close distances with a larger ship from a variety of angles and fire a very large number of missiles that the targeting computer would have to deal with in addition to the fighters themselves.
And to be frank I wouldn't really expect any weapon large enough to shoot down a fighter to be reasonably expected to have more than 1/100th a degree of precision at the very most, which is just 9 miles effective range. If you can only get one-tenth a degree of precision for the weapon, you'll be able to see Luke Skywalker in his cockpit at less than a mile. At one degree of precision, an A-Wing may crash into your bridge, since your effective range is now 4700 feet.
