Outsider Ground War

[discord]

daelyte: a third issue is that as you want to achieve higher velocity the acceleration goes up...guestimate here, but it should be some kind of square of the velocity you want, basically the acceleration goes up fast as bloody hell.

example guestimate.
take a 2km long barrel, and you want to accelerate a 1kg slug to .1c, you will need to exert force on that slug in excess of the event horizon of a black hole...i think, it's silly high anyway.
lesse, .1c travels 2km in 1 15000th of a second, but since it is accelerating it takes twice as long'ish.
acceleration time, 0.00013 seconds. speed to achieve, 30000km/s then we just apply division of these and see what we get....225000000km/s/s or about 750 times the gravitic pull of the event horizon....give or take a tad bit.


whatever, as you can see you need to take time in the barrel into the equation to get a accurate picture of how silly relativistic mass drivers are.

hmm, 5km long track and 2190km/s....
5/2190=0.0023
*2=0.00456
2190/0.00456=473040km/s/s which is only 50% or so above the event horizon of a black hole.....

now, if someone more secure in their math and physics skills could check my numbers and see if i have fucked up somewhere i'd appreciate it, never even finished junior high and that was ages ago, but it seems to be in the right ballpark area....

[Just a Crazy-Man]

sounds like your on to something.

[fredgiblet]

daelyte: a third issue is that as you want to achieve higher velocity the acceleration goes up...guestimate here, but it should be some kind of square of the velocity you want, basically the acceleration goes up fast as bloody hell.

It's squared when you DON'T count efficiency loss, which is likely to be very rapid.

[daelyte]

The first problem is how to subject any projectile to that much energy without vaporizing it.

That depends not only on the velocity but also on the efficiency of the coil gun, and on the material the projectile is made of. If a material with a higher specific heat and/or melting point can be used, the efficiency can be lower, and likewise if the projectile includes some kind of heat sink or can be cooled somehow.

A faction that has neutral particle beams, particle cannons, antimatter containment, antigrav and inertial dampers is probably well acquainted with advanced magnetic fields, and high energy systems. If something other than magnetism can be used to propel a slug, then heat due to magnetic turbulence may not even be a problem at all. It could be an antigrav gun, for example.

99.93% efficiency would keep my first example below melting point of iron. The second example would need 99.999% efficiency to avoid melting an iron slug.

How much heat do ships have to vent while sustaining 30g acceleration for several minutes?

Getting an 800 kt ship up to 3000 km/s velocity would take 3,600,000,000,000 terajoules of energy, which at 99.93% efficiency (combined efficiency of powerplant and drive) would get the whole ship up to a temperature of 3152 K, enough to melt iron. Better have good air conditioning.

The second is how you accurately aim a 5km-long barrel at a moving target.

Depends on how fast the target is moving, and how far. For a spaceship moving 1 light second away at a speed of 3000 km/s, you would only need to adjust your aim by less than 1/10 of a degree. That's not a lot of rotation compared to typical maneuverability for Outsider spaceships.

@discord:
480,000 km/s/s actually but that's acceleration not velocity.

I based my calculation on the same total energy as an 800 kt ship sustaining acceleration at 600 m/s.

[Just a Crazy-Man]

What else?

[GeoModder]

Hitting a target over a distance of a lightyear?

[discord]

daelyte: that was the idea, the 'pull' on matter at the event horizon should be pretty much c/s which should translate to about 300000km/s/s acceleration....again, both my math and physics are less then perfect, which is why i asked for a second opinion.

oh, and i did remove some excess precision when i printed it out, but not when i calculated it....difference is probably there, yup, that's it, almost 2% error...still silly numbers.

and on the huge space gun of doom(tm) it still has the problem that during the 137 seconds it takes for the projectile to get to the target, it could be 41km away in just about any direction from where you aimed it....and just a question, how exactly do you propose to create a GUIDANCE system that can survive the sudden acceleration greater than the pull of a bloody black hole.....well, greater then the threshold for it becoming a black hole anyway, that should be about as subtle as whacking it with...well itself, so before this round works, one of the criteria is that it can take the hit of itself hitting it....and still function?

again, i state silly.

[Just a Crazy-Man]

So orbital artillery to intercept incoming fleets. But smaller ships can use there speed to slip through.

[daelyte]

@GeoModder:
Thanks for catching that. I meant a light second. Fixed

@discord:
The event horizon doesn't create a black hole, it's the other way around.

"A misconception concerning event horizons, especially black hole event horizons, is that they represent an immutable surface that destroys objects that approach them."

The acceleration itself is ok so long as it's applied evenly in a linear direction, but whatever you use to accelerate the projectile may create turbulence. That turbulence costs you energy (inefficiency) and the tensions heats up the projectile (waste heat). If it gets hot enough, it will melt or even vaporize. If your launcher is very efficient there will be less turbulence, and less heat. This can be calculated based on the whole velocity rather than the acceleration.

Making the barrel longer would proportionally reduces the amount of acceleration needed. Make it 50 km and you "only" need 48,000 km/s/s acceleration to reach the same velocity. If your overall efficiency is the same this would heat up the projectile just as much and cause the same problems.

and on the huge space gun of doom(tm) it still has the problem that during the 137 seconds it takes for the projectile to get to the target, it could be 41km away in just about any direction from where you aimed it....

If you go the hybrid route, a 50/50 hybrid could maneuver sideways at half the speed of a full missile, with 70% of the forward velocity of a full slug so it still gets there in about 193 seconds.

Also like I said you'd want to shoot a lot of these to increase the chances of a hit, sort of like an AA gun.

how exactly do you propose to create a GUIDANCE system that can survive the sudden acceleration

That shouldn't be a problem, but if the projectile heats up due to magnetic (or gravitic) turbulence, the guidance system and drive/propellant would have to be able to survive that.

So orbital artillery to intercept incoming fleets. But smaller ships can use there speed to slip through.

Exactly, a fighter ship would probably have a higher drive to mass ratio and a narrower profile so these slugs would have a much harder time hitting them. You'd have to rely on other weapons for those, I think.

At closer range you could switch that same power output to lasers and plasma cannons for higher velocity intercepts. Those could more easily be on turrets to deal with wider arcs of fire, and the advantage of that orbital platform would now be higher energy output and continuous rate of fire.

At much longer ranges (light minutes maybe), the slugs could coast without having to expend any energy, until they're close enough to start maneuvering for the final chase. If they can sneak up to relatively close range before the targets realize they should evade, they might have a chance to hit something. I'm not sure how worthwhile this would be.

[Just a Crazy-Man]

Very interesting.

[discord]

daelyte: so, something can't be destroyed by acceleration as long as the force is evenly applied in a linear direction, interesting.

<stupid redneck mode>
and no, the 'event horizon' is not what creates a black hole, i aint THAT stupid, but if it does not have one it can't BE a black hole, now can it?
</stupid redneck mode>

you are aware that sudden impact is just a rapid deceleration, right? combine that with differential density which would be needed by ANY form of engine i can think of and the force would not be 'evenly applied' even in a theoretically perfect scenario.

the effect of that sudden acceleration would be significantly less then compared to dropping it from orbit and the 'rapid deceleration' of hitting the ground, it would over a longer time at least(hitting the ground that is).

and with those kinds of forces a solid steel slug would probably deform rather badly, without any heating involved, heck softer metals already do that in ordinary firearms, and those only apply very small forces in comparison, at the levels you are proposing steel would probably be liquid, or maybe go straight to plasma state....i dunno, but apply huge amounts of force on things in a very short amount of time and interesting things happen.

what i am saying is at that kind of acceleration simple inertia would be like running into a wall.

[daelyte]

you are aware that sudden impact is just a rapid deceleration, right?

Deceleration is not the problem, compression is. Sudden impact causes compression, and usually does so unevenly. Compress something enough and you can squeeze out all the other particles until you get neutronium, compress it some more and you get a singularity. It doesn't matter whether you do it quickly or slowly.

combine that with differential density which would be needed by ANY form of engine i can think of and the force would not be 'evenly applied' even in a theoretically perfect scenario.

To the extent that force is applied unevenly, it would heat up the object and possibly cause distortions.

Of course no scenario is perfect, the question is how close does it have to be, how evenly does the force have to be applied.

If you're using magnets there will be turbulence because the magnets and the ferromagnetic object are imperfect. Superconductors for the magnets and projectiles made with advanced materials would be better, but still probably not good enough for this much velocity IRL. Whatever Outsider uses for antigrav and inertial dampers might be better than any kind of magnet, and might be able to affect materials that are not ferromagnetic.

and with those kinds of forces a solid steel slug would probably deform rather badly, without any heating involved, heck softer metals already do that in ordinary firearms

The force in firearms is not applied very evenly at all.

at the levels you are proposing steel would probably be liquid, or maybe go straight to plasma state....i dunno, but apply huge amounts of force on things in a very short amount of time and interesting things happen.

The amount of distortion and heat depends on how evenly the force is applied, and that depends on how much imperfection there is in whatever fields and materials you're using.

[discord]

daelyte: not to forget, if you use gravitic forces to move the projectile, since magnetic is obviously not acceptable, i must point out that the gravitic force needed is greater then that at the event horizon, that means some hellishly focused gravitic forces, since if even a millionth part not perfectly contained would probably distort your cannon....now that i think about it, the same is true for magnetic.


but seriously, at that kind of acceleration simple inertia would probably tear it apart, since even a single effing molecule out of balance would probably be enough for it to 'unevenly apply force'.

<edit>
starting to think you might be trolling here...but i will give you some nice words to think about.
"in theory there is no difference between theory and real life, in real life there is difference."
what you are talking about MIGHT be theoretically possible, although i doubt it, but in reality? not gonna happen, that kind of precision can't be done even under laboratory conditions, much less on a weapon platform, not without going to lensman style superscience.
</edit>

[Just a Crazy-Man]

You also have to count that we don't know everything.

[discord]

crazy guy: we also have a pretty good idea of how to manage superluminal travel(FTL speeds), there is a step we don't know about, which is how to create spatial curving, some current theoretical stuff should lower the energy requirements from absolutely silly to perhaps doable, still need to figure out how to do this space curving thing though....

using a similar technique for munitions might work, but then it is very much a guided missile, not a projectile.

this is bleeding edge stuff, and would not apply to a hyper velocity mass driver anyway, the physics of making stuff go faster are pretty well understood already.

point is, inertia(you know the effect that stuff does not want to change direction nor velocity) would make even a solid steel slug just squish with that kind of pressure, heck, the energy is probably enough to disassociate molecular bonds creating a frigging cloud of particles, talk about scattergun....and how to transfer such enormous amount of energy in such a short time....it's silly.

[daelyte]

@discord:
Out of sequence, but figured this bit should be first to put this discussion in perspective...

what you are talking about MIGHT be theoretically possible, although i doubt it, but in reality? not gonna happen, that kind of precision can't be done even under laboratory conditions, much less on a weapon platform, not without going to lensman style superscience.

Well duh. We're speculating about a superweapon in a soft scifi universe.

There's plenty of stuff in Outsider that's unlikely to ever be possible in reality.

In real life, an iron projectile from a high tech coilgun with superconductors might be able to reach 550 km/s with an efficiency of 99% and avoid melting it, but that's as far as foreseeable technology can take us. If we had the kind of tech available in Outsider, higher efficiency might be possible, but it's likely to remain scifi for a long time either way.

if you use gravitic forces to move the projectile, since magnetic is obviously not acceptable

If magnetic technology is more mature than gravitic technology, it might actually be the better choice for more stable fields and higher velocity. The downside is that a magnetic gun would somewhat restrict what you can use for a projectile, since magnets have no effect on some materials, whereas a gravitic gun would have more options.

i must point out that the gravitic force needed is greater then that at the event horizon, that means some hellishly focused gravitic forces, since if even a millionth part not perfectly contained would probably distort your cannon...

Maybe not a millionth part, and the projectile might vaporize at lower imperfections than would be required to damage the gun itself, but yes I agree this is the main problem. That's also the main thing holding back fusion power IRL, not to mention matter/antimatter power, because it takes much more precise control than making a bomb with it.

at that kind of acceleration simple inertia would probably tear it apart, since even a single effing molecule out of balance would probably be enough for it to 'unevenly apply force'.

I don't think so. We can probably already manufacture a projectile good enough for that, and it would be even easier in microgravity. It does mean we couldn't just use raw ore or outsource the manufacturing to some low tech slave planet.

I think the quality problem lies less with the projectile, and more with the gun itself. It has to apply a total force of 2.4 terajoules of kinetic energy in a fraction of a second, without more than 0.07% ending up as turbulence or it will melt the projectile. That's very accurate no matter what kind of force fields. If the powerplants and magnets can't handle that, you'd need a lower acceleration and a longer gun to reach the same muzzle velocity, and your rate of fire would be slower as well.

inertia(you know the effect that stuff does not want to change direction nor velocity) would make even a solid steel slug just squish with that kind of pressure, heck, the energy is probably enough to disassociate molecular bonds creating a frigging cloud of particles, talk about scattergun....and how to transfer such enormous amount of energy in such a short time....it's silly.

Inertia is not pressure. Applying pressure to the back of a projectile would move some molecules before others, causing compression. Even if the internal stress isn't enough to distort the projectile it would turns into heat, and if there's enough heat it would eventually melt or vaporize the projectile.

That's where a coilgun (or gravgun) could be different. The kinetic energy needed to move something at 2192km/s (or any speed) wouldn't dissociate molecular bonds so long as they're all moving together, because they are in the same position relative to each other so there's no internal stress. Imperfections in the fields or how they apply to the projectile would cause some stress, but there's a tolerance based on the mass of the projectile and what it's made of. For iron that tolerance is sufficient to handle 0.07% of the total energy needed to move its mass at 2192 km/s, but you might want to cool it a bit before it meets point defenses...

Transferring such enormous amount of energy in such a short time is one of the key problems, the other is doing so without melting the projectile due to turbulence in your fields, and both of those together would limit the muzzle velocity and miniaturization that can be attained at any specific tech level.

[Trantor]

Well duh. We're speculating about a superweapon in a soft scifi universe.

IMHO discord referred to the "usual" gap between theory and practice, and since this gap is kinda "universal law" it would appear in a SF world, too.
Otherwise i would suspect the level and pattern of perfection disturbing...

Maybe not a millionth part, and the projectile might vaporize at lower imperfections

...

the other is doing so without melting the projectile due to turbulence in your fields

Maybe here´s not only the problem, but also the key to solution: Partly "ablative armor" as heat sink? And/or creating a "plasma channel" against atmosphere?

[Just a Crazy-Man]

Just to ask what about a mobile super mass driver?

[Dragoon]

Going from past history Super Guns tend to be woefully wasteful in terms of resources and manpower. The "Schwerer Gustav" and Dora guns in WWII, as well as the aborted V-3 "London Guns" were massive sinkholes which millions of dollars, tons of resources, and literally thousands of troops were poured down.

"Schwerer Gustav" took over 250 to assemble the gun, 2,500 to lay track and dig embankments. 2 Flak battalions to protect the gun from air attack. which basically tied up an entire division to support a weapon that fired one shell every 30-45 minutes. Yes it was a very big, very powerful round but in the final analysis the guns were a waste of effort on the part of the Nazis

The V-3 project was cancelled mainly due to the fact that the RAF bomber the construction sight to rubble every time the German military tired to build the thing.

The last attempt at a super gun Was Project Babylon by one Gerald Bull. it was immobile, required more materials and men to build than a couple hundred conventional artillery pieces. and led to it's designer stopping bullets with his head, chest, face...etc....( seems someone didn't want that project finished and was very willing to kill the person behind it.)

Now we can draw a few conclusions based on history, It seems that technology and the raw power of a weapon are not the deciding factors in whether or not it's effective. If it requires more resources than a division of regular forces. and requires specialized transport, support facilities, and highly specialized crews. then it is likely not to be very effective. ( See "Schwerer Gustav" and Dora.)


If a super weapon has the potential to defeat an enemy or cause significant damage to their war plans. then they will resort to drastic measures to make sure the weapon is not completed, or destroyed before it can be put into use. ( see Bull gun and The V-3)

]
So we can "guestimate" that similar factors would limit the Loroi and Umiak ability to manufacture deploy and make full use of any ground based super weapons. Similarly Using a mobile super weapon, ( See Bismark, Tirpitz, Graff Spee, Yamato, Musashi..and the Death Star)

instead I am of the opinion that the best defense is simply to try to keep the enemy over the horizon with limited planetary defense weapons, of smaller more practical sizes, and preferably mobile enough to avoid easy detection and destruction ( See V-3).
Keeping the enemy from simply parking over your head and bombarding you to dust is about all you can hope for. If your lucky you can force the enemy to make a costly and difficult assault using land and air forces, which gives the ground defenders a real edge.

[daelyte]

Just to ask what about a mobile super mass driver?

A mobile platform has to be smaller and lighter or it will require huge engines to move it, and a lot of manufacturing to make those. Because of this, mobile mass drivers would be noticeably less super.

Shorter coilgun leaves less time for acceleration, and less powerplants / heatsinks would provide less power for both projectile acceleration and higher mass projectiles. Don't forget to keep some energy for life support, propulsion, other weapons, etc.

All of which means mobile mass drivers would probably have to fire smaller and slower projectiles than a coilgun mounted on a (relatively) static platform. They could still be useful for point defense, or to kickstart missiles, neither of which requires amazing velocity.

Going from past history Super Guns tend to be woefully wasteful in terms of resources and manpower.

That's why you don't see me talking about a 3476 km coilgun built right through the diameter of the moon. It could (field efficiency aside) accelerate something to 0.19c for the same power consumption as a cruiser, or get something to 2192 km/s for 1/250th the power of a cruiser at a semi-reasonable 1920km/s2 acceleration. The problem is that a 3476 km coilgun would be a lot of work to build, and it's only good for that one emplacement. Why use a moon when an average asteroid will do?

Instead I am of the opinion that the best defense is simply to try to keep the enemy over the horizon with limited planetary defense weapons, of smaller more practical sizes, and preferably mobile enough to avoid easy detection and destruction ( See V-3).

These would not prevent the enemy from using planetary bombardment from high orbit or beyond. All it would do is prevent them from using more surgical strikes, and make it difficult for them to invade.