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Are space fighters really impossible in realistic Sci Fi?

  1. Sep 28, 2018 #1
    TL;DR at bottom


    It'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.
     
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  3. Sep 28, 2018 #2

    CWatters

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    How would he know it was coming?
     
  4. Sep 28, 2018 #3

    CWatters

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    On my space craft I will have a diverging beam laser so I only have to point it in the general direction of the enemy to score a hit. Delivering enough power over such a large area won't be a problem becuse this is fiction.
     
  5. Sep 28, 2018 #4

    Drakkith

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    So install the laser in a weapon's bay or pod that is longer than 10 meters and move the entire pod/bay. That way you have a longer lever arm to work with. Or use a lens with a variable refractive index that can alter the direction of the laser beam without physically moving. Or use a lens with a variable shape that does the same thing. Or... well, you get the idea.

    Also keep in mind that a laser beam expands as it travels, so your targeting systems don't need to be nearly as accurate as you've calculated.

    I don't know how you calculated this kind of limit on the precision, but it's almost certainly wrong. The airborne laser system was already used to destroy targets with a diameter comparable to the size of your fighters from hundreds* of kilometers away.

    *I was unable to quickly find the range-to-target during one of its tests, but the advertised range has consistently been 300+ km. The tests almost certainly would have been at ranges far greater than 9 miles though.
     
  6. Sep 28, 2018 #5
    It's just some basic trig. But honestly, I would need to see a source on that.

    Yeah, this is the sci fi forum.
     
  7. Sep 28, 2018 #6

    Drakkith

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    I don't have a single link, but a quick google search should turn up plenty of articles on the airborne laser.

    On a related note, the U.S. military has already tested a smaller scale air-to-ground laser that was able to hit a 3x3 ft target. They don't give the actual range for this test (advertised range for the project was 20km), but it will have to be at least several miles since the operating aircraft is going to be flying several miles high. Given that current laser weaponry is still in the early prototype phases, I see no reason to think that a drastic increase in power, accuracy, and range is possible. Especially in space where the atmosphere doesn't muck things up.

    Links for the above: http://www.nydailynews.com/news/wor...dvanced-tactical-laser-plane-article-1.317841
    https://en.wikipedia.org/wiki/Advanced_Tactical_Laser
     
  8. Sep 28, 2018 #7

    Drakkith

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    Just to clarify, I don't subscribe to the view that fighters are useless in realistic sci-fi. Space combat is so far into the future that I don't think it makes sense to rule them out. Who knows what kind of technology we'll have by then.
     
  9. Sep 29, 2018 #8
    My frank opinion is that the whole laser-mania is actually very ridiculous and so far away from our actual knowledge that 'realistic' space warfare based on lasers can only be about faiths.
    BTW I found the solid projectile based weaponry in the new BSG series quite well 'designed'. With fighters included.
     
  10. Sep 29, 2018 #9

    CWatters

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    I asked because the target can't see or detect it coming. That would require faster than light communication.
     
  11. Sep 29, 2018 #10

    Bandersnatch

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    I believe the idea is that the crafts would approach one another already performing evasive manoeuvres. The defender 1 light-second away detects the attacking fighter in a second-old position, shoots, and the shot arrives a second later for a total of 2 seconds delay (or 2.5 in the example mentioned by the OP) during which the target can manoeuvre out of the way.

    The 2.5 seconds is already doubled from the 1.25 light-second distance. The shooter doesn't have to wait 5, or even 2.5 seconds to update firing solutions - they can do so continuously, with each shot fired at 2.5 s delayed target.
    A sensible approach from the defender's perspective would be to spray the solid angle of the target area with repeated shots, each targetted at a different possible evasion path. There's only so far a craft of a given size can move to in 2.5 seconds, and the defender has a lot of time to keep trying to score a hit.
    Same with kinetic weapons - rather than firing a single slug, spray the area with small projectiles.

    In order to make a fighter survivable, one has to introduce some additional, arbitrary constraints. E.g. the laser can only fire every so often, and we can only have one laser, etc.

    I take the second point about aiming accuracy, but one has to wonder what is the point of sending a fighter anyway? In space projectiles have unlimited range, so there's no need to have a weapons platform deliver ordnance at close quarters. Why not just send missiles right away instead?
     
  12. Sep 29, 2018 #11

    BWV

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    Humans in fighters would be the silly thing, AI would be able to operate the craft and then it could take G forces that would kill a human

    ‘Shotgun’ blasts of small projectiles travelling at relativistic speeds would seem to be an effective weapon

    Also just detonating a 100+ megaton nuke and the associated emp would also be effective
     
  13. Sep 29, 2018 #12

    Drakkith

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    Not really. A nuclear blast in empty space generates a much smaller EMP than you would think. And it is already quite possible to EMP-harden vehicles, aircraft, and facilities.
     
  14. Oct 1, 2018 #13
    Attackers would be coming in behind assorted decoys plus a cloud of chaff and buck-shot, while big target is similarly throwing chaff and buck-shot. Plus small, point-defence missiles, essentially smart rocks...

    You also get a 'battle of algorithms' as target tries to anticipate attackers' evasive manoeuvres, then looses the heavy weapons...

    This is not a scenario for pilot survival...

    IMHO, the only reason to go near an opponent, assuming you can match their high Delta-V, is studying wreckage to gather intel...
     
  15. Oct 17, 2018 #14
    It seems finding a way to hack a system using radio waves or just using EMPs would be more effective and less risky than drones. Until that game is figured out and then everyone starts using their super advanced technology to make massive electormagnetic shields or something.

    I don’t know, but it seems that if two groups have similar technology this far advanced, attacking out right is a lose-lose scenario. And since you can never be sure if you even match your opponent in technology, unless you were desperate how could the risk justify an attack?

    Subterfuge seems the best class of weapon here: establish peaceful contact and then betray.
     
  16. Oct 17, 2018 #15
    I'm no gamer, but I've watched a nephew battling a swarm of 'Almost AI' opponents during a totally hectic single-player 'shoot 'em up'. IMHO, there were several algorithms in play, and scant time to spot cues for which foes would do what...

    He was VERY GOOD, but those opponents could be cranked up to 'insane' numbers and/or speed for teams...

    In fact, the only way to tackle such would be to have similar, scary-fast, 'Almost AI' combat bots and drones on your side.

    As I see it, once your drone-carriers salvo, any wet-ware is out of the loop barring strategic oversight. Micro-management is impossible, there are simply too many ways to hack data streams and command links. Formation turns will be based on bird or bat flocking, based on near-neighbour awareness...

    How could the risk justify the attack ?
    Politics, Ideology, Group-Think, a 'Secret Weapon', a 'First Strike' decapitation, Maskirovka, concentration of forces etc etc etc...
    {Shiver...}
     
  17. Nov 1, 2018 #16

    jbriggs444

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    It is a similar problem faced by world war II bomber pilots navigating over enemy flak at high altitude. The targeting algorithms are aiming for your projected location. You dodge proactively.

     
  18. Nov 1, 2018 #17

    CWatters

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    So I guess we are in a fictional world where we haven't yet invented faster than light travel, or we have invented it but our lasers still go at light speed.
     
  19. Nov 1, 2018 #18

    jbriggs444

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    Maybe there is a cube square relationship that makes it impractical to install a geometroconfabulator on a platform smaller than a fighter. Or the space time curvature present near any mass concentration worth fighting over multiplies the inaccuracies of hyper speed navigation, making accurate FTL targetting impractical. i.e. Whatever the plot requires.
     
  20. Nov 1, 2018 #19

    BWV

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    Again, how could humans flying a space craft compete with robot craft that could withstand, say 10G acceleration that would kill a human pilot?
     
  21. Nov 1, 2018 #20

    CWatters

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    I agree but just for info 10G is survivable for humans. I think it's the limit imposed on Red Bull air racers.
     
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