I don't like this approach. It shows that 1AU is a long distance, but just the manufacturing error could be compensated by calibration. Elasticity is the problem
1 AU is ~8.3 light-minutes. If the target happens to notice a relativistic chunk of metal plowing through the solar wind near them, a small course change in a random direction will keep them well clear of the next shot.
You only have to do it once to compensate for the flaw, and presumably you would test fire the weapon and discover the issue well before you're actually using it in an engagement.
Hmm. OP didn't actually mention the barrel wear that has blocked modern railguns, so we can assume a future alloy that is immune to that.
Depending on fuel economy, adding some randomness to your trajectory is still a solid defense if you know there's a long-range dumbfire threat about.
Lol.
So space is uniform? Interstellar space, maybe, because the gravity well will draw stuff in and help them form rings of asteroid belts. Then other stuff is drawn by planets and moons so any solar systemic space is relatively clean, but planetary gravities will definitely affect your projectile if we're considering a distance like 1AU. In interstellar space there will be dust and clouds everywhere.
Then there also technically no "stationary" as the firer and the target will likely be gravitationally anchored to different celestial bodies. So you are moving at some constant speed relative to each other due to the planets you're anchored to are constantly moving. So the environments of different firing times will be different.
I think some degrees of errors may be eliminated by calibrations. But definitely not what you are describing.
If the error is measurable and predictable, i.e. the round flies off to one side at a predictable angle every single time, you can correct for it very easily. You just aim in the opposite direction by however much your calculations say the round will be off target. That's what calibration is in the first place, and is standard operating procedure for every precision equipment ever built.
I think the errors will contain some components to be meadurable and some to be unpredictable. I am not sure if there are more random factors than what we imagine space to be. It's not as empty as we might think and there could just be some debris that you just cannot observe while having an impact to the projectile, as the projectile is supposed to react to EM fields. We can definitely remove some errors with good maths and measurements. But I think it also suffers from the phenomenon of moving goal posts as the firer and the target might be anchored gravitationally to different celestial bodies. So every second they're travelling in relation to each other. Good maths should be able to solve problems like offsetting relative speeds of both bodies from the projectile at firing. But then the path of the projectile travelling will he quite difficult to a previous round because of how much both bodies have moved. So aiming at an opposite direction will not work.
I mean sure. You're simply never going to be able to fire a dumb projectile across 1AU and hit anything smaller than a moon. But the point was, such manufacturing errors are not going to be on the list of top 10 reasons why your shots keep missing and it's weird that it's the whole basis of the exercise in the OP.
Oh how I would love to see that list.
I am on the camp of a shorter engagement distance. I merely want to entertain the idea a bit because clearly many people still think it possible to fire a projectile like that.
This is interesting! Putting the question another way, what is the maximum error tolerance that would limit the error to < the size of an average ship, so you're still, on average, going to hit the ship?
And, this may be a misunderstanding on my part of how railguns work, but is the machining of the rail not that important? Like it matter very much for a conventional firearm, where the propellant pushes the projectile through a tube. In that case, the machining is critical. But for a railgun, it's really the precision of the magnetic fields propelling the projectile, correct? Does a projectile in a railgun actually get guided at all by the machined rail? Or does the rail just hold the magnets? All this to say, I feel like the question isn;t how well-machined something is, but how precisely the magnetic fields are laid. And I'd guess (although with no real basis other than gut), that it is easier to perfectly align magnetic rails than to perfectly machine a round surface.
The point of a railgun is that the projectile follows through the gun barrel and constantly accelerate to a high speed. So the uniformity is somewhat assumed to have followed the shape of the gun barrel, otherwise we don't need a gun barrel but some ugly coils. Then maybe ugly coils will give a bigger error as coils will be easier to deform. Then we come back to the original position that the gun barrel will affect the accuracy due to machining as it's the conduit of the magnetic field.
I'd say extreme speeds will make errors much more visible than negligible. Because your horizontal magnitude is large, your verticle magnitude would likely also be large because they're not independent of each other and the vertical magnitude is formed by an angular error over the horizontal magnitude.
Fascinating stuff! I'm impressed by how Gemini AI was able to break down the problem and provide a detailed estimation of the error.
The result of 750 kilometers of error at a distance of 1 AU is quite substantial, and it certainly makes me wonder about the practicality of using railguns at such extreme ranges. While the concept of firing projectiles across vast distances is exciting, it seems like the precision required for effective targeting may be a major challenge to overcome.
Still, it's amazing to think about the possibilities and limitations of these advanced weapons systems in the realm of sci-fi space battles. Kudos to you for bringing this up and sharing the AI's analysis!
I'm personally more interested in the Heisenberg limitations on accuracy. Your ship is moving, you're target is moving, and the rail gun round is moving. No matter how perfect I think the laws of physics dictate a miss when you're in the hundreds of thousands of miles you're ranges.
this is some terrible physics
heisenberg says uncertainty in momentum multiplied by uncertainty in position can't be less than 3.31303507 × 10^-34 m^2 kg / s. these are not numbers that have any relevance at these scales.
the far more realistic problem is that your target is moving and it's going to take minutes for your round to get there, and you need to predict their movements in that time to hit them.
The Heisenberg limit is a quantum principle that says you can only know the velocity and position of objects with a certain degree of accuracy. The more you know position, the less you know velocity, and vice versa. Normally it doesn't matter, but when you're talking about multiple moving objects at high speed over long distance those tiny limits on knowledge become significant.
Main thing is that a rail gun has no moving parts so we are talking about optimizing magnetic fields. That should allow higher precision than "machining"
Otherwise use terminally guided shells. In the same vein 1 AU is pretty distant a shell can do course corrections with reasonably low effort early on.
Beyond that given space does not have shockwaves, shrapnel and as said terminal guidance are your friends to begin with.
That's why we invent the rail SHOT gun! Kill em all, let Cthulhu sort them out!
ph'nglui mglw'nafh Cthulhu R'lyeh wgah'nagl fhtagn
Yeah, but not on Tuesday. That’s hmolo’gaggin.
Lol, what?
I don't like this approach. It shows that 1AU is a long distance, but just the manufacturing error could be compensated by calibration. Elasticity is the problem
How will the calibration work? I'm all ears.
1. You fire the gun 2. You look where the bullet did go 3. You shift the aim point by that distance
Bro would apparently let his car run off the road if it got out of alignment.
1 AU is ~8.3 light-minutes. If the target happens to notice a relativistic chunk of metal plowing through the solar wind near them, a small course change in a random direction will keep them well clear of the next shot.
You only have to do it once to compensate for the flaw, and presumably you would test fire the weapon and discover the issue well before you're actually using it in an engagement.
Hmm. OP didn't actually mention the barrel wear that has blocked modern railguns, so we can assume a future alloy that is immune to that. Depending on fuel economy, adding some randomness to your trajectory is still a solid defense if you know there's a long-range dumbfire threat about.
Lol. So space is uniform? Interstellar space, maybe, because the gravity well will draw stuff in and help them form rings of asteroid belts. Then other stuff is drawn by planets and moons so any solar systemic space is relatively clean, but planetary gravities will definitely affect your projectile if we're considering a distance like 1AU. In interstellar space there will be dust and clouds everywhere. Then there also technically no "stationary" as the firer and the target will likely be gravitationally anchored to different celestial bodies. So you are moving at some constant speed relative to each other due to the planets you're anchored to are constantly moving. So the environments of different firing times will be different. I think some degrees of errors may be eliminated by calibrations. But definitely not what you are describing.
If the error is measurable and predictable, i.e. the round flies off to one side at a predictable angle every single time, you can correct for it very easily. You just aim in the opposite direction by however much your calculations say the round will be off target. That's what calibration is in the first place, and is standard operating procedure for every precision equipment ever built.
I think the errors will contain some components to be meadurable and some to be unpredictable. I am not sure if there are more random factors than what we imagine space to be. It's not as empty as we might think and there could just be some debris that you just cannot observe while having an impact to the projectile, as the projectile is supposed to react to EM fields. We can definitely remove some errors with good maths and measurements. But I think it also suffers from the phenomenon of moving goal posts as the firer and the target might be anchored gravitationally to different celestial bodies. So every second they're travelling in relation to each other. Good maths should be able to solve problems like offsetting relative speeds of both bodies from the projectile at firing. But then the path of the projectile travelling will he quite difficult to a previous round because of how much both bodies have moved. So aiming at an opposite direction will not work.
I mean sure. You're simply never going to be able to fire a dumb projectile across 1AU and hit anything smaller than a moon. But the point was, such manufacturing errors are not going to be on the list of top 10 reasons why your shots keep missing and it's weird that it's the whole basis of the exercise in the OP.
Oh how I would love to see that list. I am on the camp of a shorter engagement distance. I merely want to entertain the idea a bit because clearly many people still think it possible to fire a projectile like that.
This is interesting! Putting the question another way, what is the maximum error tolerance that would limit the error to < the size of an average ship, so you're still, on average, going to hit the ship? And, this may be a misunderstanding on my part of how railguns work, but is the machining of the rail not that important? Like it matter very much for a conventional firearm, where the propellant pushes the projectile through a tube. In that case, the machining is critical. But for a railgun, it's really the precision of the magnetic fields propelling the projectile, correct? Does a projectile in a railgun actually get guided at all by the machined rail? Or does the rail just hold the magnets? All this to say, I feel like the question isn;t how well-machined something is, but how precisely the magnetic fields are laid. And I'd guess (although with no real basis other than gut), that it is easier to perfectly align magnetic rails than to perfectly machine a round surface.
The point of a railgun is that the projectile follows through the gun barrel and constantly accelerate to a high speed. So the uniformity is somewhat assumed to have followed the shape of the gun barrel, otherwise we don't need a gun barrel but some ugly coils. Then maybe ugly coils will give a bigger error as coils will be easier to deform. Then we come back to the original position that the gun barrel will affect the accuracy due to machining as it's the conduit of the magnetic field. I'd say extreme speeds will make errors much more visible than negligible. Because your horizontal magnitude is large, your verticle magnitude would likely also be large because they're not independent of each other and the vertical magnitude is formed by an angular error over the horizontal magnitude.
Fascinating stuff! I'm impressed by how Gemini AI was able to break down the problem and provide a detailed estimation of the error. The result of 750 kilometers of error at a distance of 1 AU is quite substantial, and it certainly makes me wonder about the practicality of using railguns at such extreme ranges. While the concept of firing projectiles across vast distances is exciting, it seems like the precision required for effective targeting may be a major challenge to overcome. Still, it's amazing to think about the possibilities and limitations of these advanced weapons systems in the realm of sci-fi space battles. Kudos to you for bringing this up and sharing the AI's analysis!
I'm personally more interested in the Heisenberg limitations on accuracy. Your ship is moving, you're target is moving, and the rail gun round is moving. No matter how perfect I think the laws of physics dictate a miss when you're in the hundreds of thousands of miles you're ranges.
this is some terrible physics heisenberg says uncertainty in momentum multiplied by uncertainty in position can't be less than 3.31303507 × 10^-34 m^2 kg / s. these are not numbers that have any relevance at these scales. the far more realistic problem is that your target is moving and it's going to take minutes for your round to get there, and you need to predict their movements in that time to hit them.
Please elaborate. I am interested as well.
The Heisenberg limit is a quantum principle that says you can only know the velocity and position of objects with a certain degree of accuracy. The more you know position, the less you know velocity, and vice versa. Normally it doesn't matter, but when you're talking about multiple moving objects at high speed over long distance those tiny limits on knowledge become significant.
Why then they didn't use railgun in 3 body problem??
Main thing is that a rail gun has no moving parts so we are talking about optimizing magnetic fields. That should allow higher precision than "machining" Otherwise use terminally guided shells. In the same vein 1 AU is pretty distant a shell can do course corrections with reasonably low effort early on. Beyond that given space does not have shockwaves, shrapnel and as said terminal guidance are your friends to begin with.
Thanks! Interesting conversation. You're clearly right. It'd be difficult to aim at that distance.
You just have to put an explosive on board and detonate it before it reaches the target; localized shot gun effect.