Range in Space Combat
- Thread starter Zenopath
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Space combat at extreme ranges is probably not realistic. Yes, the physics say I can shoot you at Mars from Earth, this can be completely nullified with a computer's random number generator tied to the flight control system. Since WW1, fighter pilots use random maneuvers commonly referred to as Jinking. If ships suspect combat, flip a switch and your ships if making minor variations to movement destroying targeting from all but close range attacks. Doing so would be fuel intensive, so wouldn't be enabled all the time.
Here is an example of what you are talking about, i think?
https://en.wikipedia.org/wiki/M982_Excalibur
looking it up, https://en.wikipedia.org/wiki/Orders_of_magnitude_(acceleration) suggests that our current tech allows electronics to survive;
152 210 m/s2 15 500 g Rating of electronics built into military artillery shells[26]
a slug acelerated at that gee force, across the length of a typical naval gun barrel, would hit a final speed of, um, yeah the exact formula escape me.
Thankfully I can google it, and muzzle velocity of artilery shell is 770m/s. Which in space would be pathetically slow. So we would need to provide same accelleration across a much larger barrel or longer time with a railgun, maybe, dunno. Most likely modern electronics would not survive being accelerated to 30,000,000m/s (10% speed of light) no matter how long your rail gun barrel is,
Remember that if your accel is 152,000 m/s2, and you apply that force for a full 0.1 seconds, then in 0.1 seconds, that shell already crossed 7500 meters, which would be pretty tough to fit in a warship, and would still only be traveling 15,200 meters per second, or about 1/20,000th the speed of light.
If we are speaking of missiles, they have the capability to accelerate at a slower rate over a longer distance though.
Yes, that would be the point of a missle, lol.
Actually a missile with a sustained 15,000g's of acel would be amazing and would have no problems hitting things several light minutes away, because it could hit half the speed of light in only 1000 seconds or 16 and 2/3rd minutes. So you could expect it to hit a target several light minutes away in under an half an hour, if it keeps to 0.5c cruising speed for better final approach accuracy.
(edit) a missile with acel like that would have no need of a warhead, any impact at higher than 0.1c would probably destroy anything, if we are talking about a 1 ton missile.
(edit 2) The person I replied to was asking about a rapid luanch system, like, firing a missile from a naval gun.
I was just giving him an example of what electronics can survive today, if you added a rocket engine to the above artillery shell, it it would be a naval gun launched cruise missile, which would benefit from a 770m/s head start before igniting its engines.
But, I suspect that the components of a rocket engine are not rated at 15,000g's in our current tech, the liquid would pop any kind of tank, so you would be forced to use some very sturdy solid rocket fuel in very creative ways for it not to explode at launch. But then again, if your missile has 15,000g's of acel, a rapid launch system would be redundant at best.
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Hell, anything greater than 500kg moving at .2+C would destroy most anything, unless it was very, very large. That energy of impact is equivalent to 213.67 megatons.
@Zenopath thanks, that was exactly what I was aiming at, accelerating a solid mass of ultra-dense material (your typical railway slug) is one thing, if you add something for the projectile to steer itself, that must also survive the acceleration. Electronics of course, though also the actual propulsion units, whatever they maybe, as well as the sensor suit. So having unguided ballistic rounds sounds somewhat plausible if they are to rely on sheer velocity and are accelerated by the ship.
Remember also that gravity/acceleration has an inverse (maybe inverse squared) relationship to mass and size. So the smaller you are, the less gravity and acceleration affect you. If the electronics were very small, quite likely in the future, accelerations impact on them would be negligible until you got to impossible to achieve levels. I'm talking electronics on the nano-scale and accelerations around 30000+Gs.
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There is also a big difference in being rated to survive a very very short duration burst of 15,000g's and a sustained accel of 15,000g's. To an artilery shell, the explosion that gives it it's speed happens very very quickly, so the electronics don't have a lot of time to deform from the stress. Under sustained g forces like that, the material would probably facture, not from its own weight, per say, but from the pressure of the material around it would exert on it.
It's worth mentioning that a railgun, working with magnetic forces would put enourmous stress on objects, but if you use a gravity based system, then you wouldn't give nearly same stresses. If you manage to avoid problems with tidal forces (providing an even gravity gradient rather than a point source of artificial gravity) then you could accellerate even squishy humans at ridiculous gee's and they would never feel it. I am pretty sure that is how impulse thrusters work, anyways.
I am confused, I thought it only mattered how much acceleration energy an object receives per unit of time, is this not the case?
It matters because of deformation. Like, if you bend a piece of metal it wont bounce back, because you applied a sustained amount of force to it. But if you used exactly the same amount of force on the piece of metal by giving it a brief blow, same gee force over a tiny amount of time; It would not get bent, the material would resist a brief impact but not a long period under same amount of force. In building materials this becomes important because while concrete for example can shrug off a lot of compression force from a brief strain, like an earthquake, keeping same amount of force on it for a long time will eventfully cause it to fail.
It is the case, but it also matters how many units of time the acceleration goes on for. See above.
Despite the longer, weaker force expending the same amount of energy on the object as the shorter, stronger force?
its not the same amount of energy, if you applied 15,000g of force for 0.0001 seconds, thats the same as appling 1.5g for 1 second, in terms of energy
its why a mantis shrimp can do 10,000g's of force with its punch, because the force is applied for a very tiny amount of time. Getting hit by a mantis shrimp might sting, but it wont kill you, because its not actually that much energy.
What I was saying is that the electronics probably can only survive 15,000g for about as long as it takes gunpowder to explode, a tiny fraction of a second. Same force applied for longer, like a missle doing sustained 15,000g thrust for minutes on end, would be tougher to survive. Most materials we have today would turn into a pancake under that much force for any length of time longer than a fraction of a second.
(edit) Think hydraulic press. If you tapped it on for less than a second, you might not do any damage. If you leave it on, it will gradually crush things flat.
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kinetics could still be used, remember we're talking about sci-fi empires with FTL drives, i don't think any ammo being fired whether it's missile or ballistic based would be dumb rounds.
you can ballistically fire an object toward your target and then have it use torque wheels to orient itself and then explode sending the true intended projectile into the enemy. the electronics could be using inertial dampeners, if we're even still using metallic computing at that point.
the reason i think smart ammo would be so prevalent even though the ammo itself seems expensive, is because it will raise the odds of hitting objects significantly from much farther away, meaning you'd outrange your enemies who don't use it by potentially 10s of times.
ballistic smart ammo would have the advantage over missiles in that, if point defence starts trying to shoot at it, it won't potentially change course due to internal damage, such as an engine being hit or fuel exploding, if you're using lasers to cook the material flying at you, it will just get hotter for when it potentially hits you, instead of detonating and spreading most of the energy in the wrong direction.
we might also have ammo extending large nets of extremely tough material and if it touches anything ,it;s designed to anchor and pull the warhead into it as well.
I don't think shotgun ammo could work, as you;d just be able to have the fleet move in a more sparse formation.
you can ballistically fire an object toward your target and then have it use torque wheels to orient itself and then explode sending the true intended projectile into the enemy. the electronics could be using inertial dampeners, if we're even still using metallic computing at that point.
the reason i think smart ammo would be so prevalent even though the ammo itself seems expensive, is because it will raise the odds of hitting objects significantly from much farther away, meaning you'd outrange your enemies who don't use it by potentially 10s of times.
ballistic smart ammo would have the advantage over missiles in that, if point defence starts trying to shoot at it, it won't potentially change course due to internal damage, such as an engine being hit or fuel exploding, if you're using lasers to cook the material flying at you, it will just get hotter for when it potentially hits you, instead of detonating and spreading most of the energy in the wrong direction.
we might also have ammo extending large nets of extremely tough material and if it touches anything ,it;s designed to anchor and pull the warhead into it as well.
I don't think shotgun ammo could work, as you;d just be able to have the fleet move in a more sparse formation.
Thanks, that's how I thought it works.
The issue would be whether smart rounds would be feasible or if they would need to be much slower than dumb rounds, due to the parts needed for making the projectile smart being unable to survive the mot extreme forces of acceleration. Seems to be that a solid mass of dense matter should be able to be much stronger than anything less solid or with moving parts.
Regarding the shotgun approach, I think the idea is less trying to hit multiple ships, but to try to hi a single ship with a whole volley of projectiles.
if they have FTL they at least have technology to allow people to survive the acceleration to FTL
and a solid brick can't have even close to the accuracy. so assuming their technology that allows FTL travel, can also be made to make rounds go close to the speed of light, or even 0.1c as was mentioned earlier, you'd probably stay accurate to multiple of 10 over a dumb round, being able to attack someone for potentially minutes before they can fire back is too good of an advantage to just leave open.
on shotguns, what i mean, is to reduce the chance you don't miss by just filling the enemy space with rounds, so that you're at least hitting something, maybe not with all of the mass, but some of it, anything moving at close to superlative speeds will be effectual. however, it isn't something that can compensate for dumb rounds. space is just too big, when the space between ships can easily be 1000x it's length, dumb scattershot will not be effective. basically shooting a ton of small rounds at a single target to try to saturate all of it;s escape vectors will simply be significantly less effective than firing smart ammo (ballistic or missile based) to basically do the same thing.
In fact, i had an idea where instead of an explosive on a missile you have a high energy beam weapon that uses the electricity you generate from thrust engines to power itself. you send a missile when it gets close it turns toward the enemy ship and unloads all of it;s fuel into firing the laser instead of thrust.
more or less, i think suicide fighters manned by AI are how combat is going to work more or less. you launch something that doesn't need to return to fight the ship before it's destroyed by PD or rams into the target.
because of how dangerous PD will be against smaller craft, i see an emphasis on high alpha strike weapons, as they'll likely survive being in effectual range of their weapons for a very short time.
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I'm not sure where 15,000 gravities of acceleration for a missile or kinetic slug got its start in this whole conversation, but it honestly should just end. A missile does not need to generate more than a couple dozen gravities of acceleration to be effective over space battle distances (at the time scales shown in Stellaris), and a slug would need to be accelerated WAY over a BILLION gravities to exit a barrel at anywhere near 10% of the speed of light (e.g., 1 kg slug, 100 meter barrel, 10% c = around 460B gravities over 6.7 microseconds, 30 million Newtons of net force). Virtually any moderately robust RL-modern mechanical or electronic system can survive the missile's acceleration, but you'd have to get into some fantastically exotic materials to have anything beyond an inert slug deal with being shot out of that kind of cannon (and still do anything afterward).
If we have unlocked FTL travel, we will have some pretty exotic materials. Not to mention that you could also just integrate control circuits into the materials of the rounds via 3-D printing and other means of manufacturing, like crystal growth chambers. Use an ultradense material like tungsten alloys or depleted uranium isotopes and write the circuits with an insulator around them. Building such rounds would be trivial in an age where we've broken the Universal Speed limit.
At some point this discussion turns into "well we can just fit jump drives into our missiles and have them go inside enemy ships".
What're the baseline givens for this discussion in the first place?
What're the baseline givens for this discussion in the first place?