Comments on Librium Universe Infodump thread

[Cynical Cat]

Missile swarms are certainly possible. You should keep in mind that the Honorverse missile swarm of doom exists soley because the author cheats like a motherfucker to allow it to exist. Whether you want to cheat as badly as Weber does or want more realistic missile swarms is up to you.

[frigidmagi]

Wouldn't a multi-megaton railgun shell just punch clean through the ship without transferring much of its energy to it?

Blowing a hole through a ship is usually considered worthwhile damage.

But, it also begs the question of how the launching ship fired this beast of a shell in the first place.

Very carefully but still a point. Would gravitional control help at all with recoil? Some sort of inerta damper? Or would it be best to abandon the use of rail guns and stick to energy weapons?

[Comrade Tortoise]

Wouldn't a multi-megaton railgun shell just punch clean through the ship without transferring much of its energy to it?

But, it also begs the question of how the launching ship fired this beast of a shell in the first place. Our buddy Newton would have something to say about that.

Yes. Which is why it is safer for the ship to be unarmored so as not to even try stopping the penetration. Internal bulkheads would be used for damage control.

As for the railguns, it is easier to dissipate recoild in one spot purpose built for it than to try and do it using armor plating on every square millimeter of hull surface

[rhoenix]

No. Ablative armor would have to be explosive reactive armor in order to fend off a kinetic impact. It works against energy weapons by absorbing and boiling off the high-specific heat armor, but to nullify a kinetic impact it would have to explode with enough force to neutralize the impact, which has the same crew-killing problem.

Point taken. Well, scratch that idea, then.

The reason reactive armor works on modern tanks is because they are concerned with penetration of the armor and subsequent explosion IIRC

I was about to argue this point, but I realized that for an enemy ship, killing the crew without having to tear apart the ship would be preferable, since then you have a relatively serviceable ship you can take back home for parts and research.

Alright, scratch my ablative armor idea, then.

[frigidmagi]

Okay, CT?

A hole throughout the entire ship will cause cumulative damage and chaos through out it. It is worth doing in my opinion even if it's just a small hole.

[Comrade Tortoise]

Okay, CT?

A hole throughout the entire ship will cause cumulative damage and chaos through out it. It is worth doing in my opinion even if it's just a small hole.

Certainly, the explosive decompression alone will make sections of the ship unusable. However, while punching a hole through the ship is damaging, one crew-killing impact is preferable for the attacking side. Which is why the ships would not be armored. It is better to have a hole in the hull and have some of your ship being functional, than to have the crew turned into a paste

[The Silence and I]

I've got some thoughts on making missile swarms effective.

If energy shields are especially effective against EM radiation (seems to me the most obvious kind of hostile energy found in hyperspace) then this will cripple the range of even the best lasers, since spot size is directly related to range and also damage potential. Likewise any particle weapon, which will already have less range than a laser, should be easy enough to defeat with shielding--a strong magnetic field will do wonders--so the longer ranged direct fire weapons won't have much effect at maximum range, which brings the overall range of direct fire weapons down and forces closer engagements.

Whats left then are KE weapons and missiles (and fighters, ish). KE cannot realistically approach cee so its range will always be less than some tens of thousands of km (ish)--maneuvers will be too effective beyond that. So direct fire range is probably not more than 100,000 km or so, and we can cook up mildly implausible missiles that can cross that distance without taking hours to do so.

[The Silence and I]

Wouldn't a multi-megaton railgun shell just punch clean through the ship without transferring much of its energy to it?

LOL
In a word: "no" Any ship-to-ship-weapon-sized object containing several megatons of KE will simply flash vaporize itself and a good chunk of its target upon any significant impact. There won't be a ship to have a hole in.

But, it also begs the question of how the launching ship fired this beast of a shell in the first place. Our buddy Newton would have something to say about that.

Quite. I find the idea rather silly.

[Cynical Cat]

The cheats to enable the Honorverse missile swarm of doom:

1) Shields that give invulnerability to in universe direct fire weapons at long range (the wedge), but can be circumvented by missile fire (striking for the sidewalls)

2) A missile only drive that allows them to have an insane acceleration compared to ships. This drive won't work for ships.

3) Free energy from hyperspace so the missiles can power that continious high acceleration. In other words, free fuel and it doesn't have to worry about cooking itself from the heat of its drive.


A more realistic missile swarm is going to have a much more limited range. It will have to worry about dumping heat so it doesn't cook its computer brain and it will have only so much fuel. It will arrive at its target much later than a beam weapon, but it possesses the advantage of being able to correct its course and carrying a massively destructive warhead. Of course point defence will be a bitch. Depending on FTL system and the universe's power sources, the Dread Empire Falls relativistic missile swarm ambush might be possible.

[frigidmagi]

f energy shields are especially effective against EM radiation (seems to me the most obvious kind of hostile energy found in hyperspace) then this will cripple the range of even the best lasers, since spot size is directly related to range and also damage potential. Likewise any particle weapon, which will already have less range than a laser, should be easy enough to defeat with shielding--a strong magnetic field will do wonders--so the longer ranged direct fire weapons won't have much effect at maximum range, which brings the overall range of direct fire weapons down and forces closer engagements.

Whats left then are KE weapons and missiles (and fighters, ish). KE cannot realistically approach cee so its range will always be less than some tens of thousands of km (ish)--maneuvers will be too effective beyond that. So direct fire range is probably not more than 100,000 km or so, and we can cook up mildly implausible missiles that can cross that distance without taking hours to do so.

Damn if I don't like this. I really do like this explation and move to adopt it as the framework for space combat. Any supporting votes or objections?

[Comrade Tortoise]

I can get behind that proposal

[rhoenix]

I like this idea, but have a question before I'd fully vote for it.

What about particle beams? Unless I've missed something, they still technically fall under particle impact, though they travel very close to c. If this is the case, then some factions would likely use them as long-range strike weapons at the least.

[Cynical Cat]

Extra potency against EM weapons is jumping the gun and will also nerf nukes (although you might want that and halve the hypervelocity kinetic penetrator swarm of doom warhead). You need to determine weapon yield before you can say that. How powerful are your ship to ship lasers?

[frigidmagi]

Likewise any particle weapon, which will already have less range than a laser, should be easy enough to defeat with shielding--a strong magnetic field will do wonders--

[Destructionator XV]

An all out battle in the real world will happen in orbit where less fuel is needed and every combatant has a reason to be present.

If the Martians are coming to attack Earth, they have a reason to be in the space in between - they are passing through. The defenders would also have a reason to intercept them - to stop the attack.

Most likely you'd need unrealistic engine assumptions to accomplish that.

Yes, I agree there. However, the drive by shooting just requires you to sprinkle ball bearings in the attacker's path. He might be going 30 km/sec: those little chunks will really mess up his day.

To avoid being hit, the attackers will have to burn fuel to go around it, and then burn fuel to get back on course.

Most realistically though, those would be laid by a one way remote controlled or preprogrammed robot rather than a manned warship. I suppose it wouldn't be a battle in the normal sense, but more like on demand mining.

The defenders, if manned ships, once completing their flyby, might go on to attack the attacker's homeworld too, probably ending in a relatively boring MAD standoff.

Attackers need to get to speed once, reduce speed once, and have spare for maneuvers.

This is assuming the attackers don't want to get home.

It has used twice the delta vee of the attackers and it has to hope against hope that nobody gets past the single salvo because they ain't getting home before surviving attackers get there.

They might just be a single wave hoping to thin the attackers out for the home batteries and fleets to finish them off.

If you armor a ship fitted with real-world rocketry (modern or future) you will reduce its delta vee,

Delta-v is dependent on the fuel to mass ratio, not raw mass. If you add mass for armor, you would have to add mass for fuel as well, but you could maintain the same delta-v.

Of course, this is assuming that the armor mass grows slower than the fuel mass, but geometry gives up hope here: volume of the tanks would grow faster than the surface area of them.

Definitely makes the ships far more expensive though.

[and armor will reduce] its acceleration.

Yes, indeed. But, is acceleration really relevant? It probably isn't going to help you dodge laser beams for long anyway.* Missiles would out-accelerate any ship, and kinetics would take so bloody long to cross the gap that they are easily avoided even with pathetic acceleration.

*Dodging laser beams would be randomly moving about so the enemy ship can't get a good reliable targeting path on you. This is going to burn gobs of delta-v, meaning you won't be able to pull it off for long in any ship. To avoid sure hits, you would want enough acceleration to change your vector enough that your new profile by the time the enemy's beam arrives is entirely different than what he saw when he targetted.

Mathematically, you would want d = 9.8/2 a*t^2 to work out so d is your ships radius and t is twice the distance between you and your enemy, in light seconds (well, it is actually the time from observation to weapon impact, but that is what it would be for a laser). a is your minimum needed acceleration, in gees. This assumes instant rotation for the evading ship and the laser turret. Solve for a: a = d * 2 / 9.8 / t^2.

At half a light second, about one third the way to the moon, say your ship has a profile radius of 40 metres. a = 40 * 2 / 9.8 / 1 = 80 / 9.8 = ~8 gees. With or without armor, that is pretty nuts. This scales linearly: a radius of 20 meters requires 4 gees. 10 requires 2.

This would have to be constant and random to really throw off an enemy laser gunner. At longer range, you have a lot more time to use: double the distance, require 1/4 the acceleration. But you also need a laser reliable at this increased distance and a reason for your ships to be that far away (a perfectly valid reason would be interplanetary ships that start blasting from far away).

I think a more realistic combat range would be one or two light seconds. At one light second: 40 * 2 / ~10 / 2^2 = 80 / 10 / 4 = 8 / 4 = 2 gees. This is much more realistic, but still hard, and the fuel limitations would still hit eventually.

But, from this, it is my conclusion that trying to dodge is futile, so you had better be prepared to take a few hits and keep on ticking. Thus, I lean toward at least some armoring.


Long trips to the outer planets just require enough acceleration to fight the sun's gravity, which isn't much. After that, slow and steady works just as well.

[rhoenix]

Likewise any particle weapon, which will already have less range than a laser, should be easy enough to defeat with shielding--a strong magnetic field will do wonders--

Ah, thank you - I obviously managed to miss that.

In that case - I like the proposal, and I'd vote for it, if my vote counts.

[Destructionator XV]

LOL
In a word: "no" Any ship-to-ship-weapon-sized object containing several megatons of KE will simply flash vaporize itself and a good chunk of its target upon any significant impact. There won't be a ship to have a hole in.

This is probably the result of my own brain-bias: I always imagine railgun shells used for battle as being little bullet sized things, which would have insane speed with that much kinetic energy. My mind sees it like punching a fast needle through a piece of paper.

I have no idea though; I'm probably still wrong even with a small mass.

[The Silence and I]

Extra potency against EM weapons is jumping the gun and will also nerf nukes (although you might want that and halve the hypervelocity kinetic penetrator swarm of doom warhead). You need to determine weapon yield before you can say that. How powerful are your ship to ship lasers?

I am being very basic here but my general assumption is that if you can pump x energy into a KE impactor with a mass driver then you can pump approximately x into a laser, making them roughly equivalent in yield (but of course the KE weapon is far more destructive if it can breach the shields).

Warheads could be just about anywhere, no one's really commented here, other than megatons are thrown about--it doesn't describe relative weapon strengths.

[The Silence and I]

LOL
In a word: "no" Any ship-to-ship-weapon-sized object containing several megatons of KE will simply flash vaporize itself and a good chunk of its target upon any significant impact. There won't be a ship to have a hole in.

This is probably the result of my own brain-bias: I always imagine railgun shells used for battle as being little bullet sized things, which would have insane speed with that much kinetic energy. My mind sees it like punching a fast needle through a piece of paper.

I have no idea though; I'm probably still wrong even with a small mass.

Look up a whipple shield.

[Comrade Tortoise]

But, from this, it is my conclusion that trying to dodge is futile, so you had better be prepared to take a few hits and keep on ticking. Thus, I lean toward at least some armoring.

There is inertial compensation through artifical gravity that can handle this, so there is no reason to suspect that this level of acceleration is not possible. Additionally, we are not talking about a stationary ship vs a non-stationary ship. These ships will be accelerating relative to eachother. Additionally, there is shielding. If the shields go down, you ARE fucked.

[The Silence and I]

NOTE: This reply is assuming real-world engines.

If the Martians are coming to attack Earth, they have a reason to be in the space in between - they are passing through. The defenders would also have a reason to intercept them - to stop the attack.

Yes, but also no. There is no particular reason the two fleets would meet inside a region of space anyone would call "small." So, catching is required, and this leads to a game of tag (sort of--they are rushing towards each other) and the one with less delta vee is likely to loose.

Yes, I agree there. However, the drive by shooting just requires you to sprinkle ball bearings in the attacker's path. He might be going 30 km/sec: those little chunks will really mess up his day.

To avoid being hit, the attackers will have to burn fuel to go around it, and then burn fuel to get back on course.

What's good for the goose... also if the defenders can intercept and then return then the attackers will have a consumption advantage here (they don't have to leave the planet they attack on their own power).

If they don't win they won't be in condition to leave anyway, they only need enough fuel to get there. If they win they can take more fuel.

Delta-v is dependent on the fuel to mass ratio, not raw mass. If you add mass for armor, you would have to add mass for fuel as well, but you could maintain the same delta-v.

Of course, this is assuming that the armor mass grows slower than the fuel mass, but geometry gives up hope here: volume of the tanks would grow faster than the surface area of them.

Yes, this is why missiles don't work as well as people like to think. But every time you increase your size (the only way to add armor without sacrificing delta vee) you decrease your strength to mass ratio, and you won't be able to handle accelerations if you push that ratio too far. To have a reasonable amount of armor you need a considerably larger ship and it will have inferior acceleration just because it is big (thrust per square meter of engine is constant, your mass will outgrow your thrust, and your structural strength too) and this does not allow you to dictate engagement terms.

Yes, indeed. But, is acceleration really relevant? It probably isn't going to help you dodge laser beams for long anyway.* Missiles would out-accelerate any ship, and kinetics would take so bloody long to cross the gap that they are easily avoided even with pathetic acceleration.

Acceleration is relevant I think. You cannot out accelerate a missile, but you will have more delta vee. At any sort of long range you will have enough spare delta vee to run the missile's tanks dry--but only if you have enough acceleration to take advantage. Acceleration is also vital for dictating engagement terms. Dodging lasers is slightly silly, yes, but even there EM warfare can give you an advantage. You just have to fuddle the sensors to where the enemy isn't really sure where you ever were. You don't have to move your entire bulk either, and a realistic vessel might be cylindrical. The idea is to reduce hits, but yes it would have to work at long range only, if ever (fuel consumption is definitely a huge problem).

I think a more realistic combat range would be one or two light seconds. At one light second: 40 * 2 / ~10 / 2^2 = 80 / 10 / 4 = 8 / 4 = 2 gees. This is much more realistic, but still hard, and the fuel limitations would still hit eventually.

But, from this, it is my conclusion that trying to dodge is futile, so you had better be prepared to take a few hits and keep on ticking. Thus, I lean toward at least some armoring.

Dodging lasers will never be all that practical, but with enough acceleration you have a chance against missiles (because you have more delta vee) and you always want to out maneuver your opponent--particularly if combat takes place around obstacles as I think it usually will.

[Destructionator XV]

On the weapon yields:

2: Hyperspace is currently imagined as a place where you need to be able to absorp Kilotons worth of energy per hour or die. Hence to overload or puch through the shields low double digits megatons work best for weapons

With the new proposal for shields being very good at taking care of EM radiation but not so great on kinetics, this one can be knocked off.

It might take megaton or gigaton weapon yields to punch through the shields directly, but you can sidestep them entirely with kinetics, so they wouldn't need to be as powerful while still being effective.

3: I thought the word megaton was cooler then Gigaton or Kiloton. Yes I know Gigaton is bigger, so what?

How do you like 'megajoule'? Consider the advantages to lower energy levels: you could take many hits from them and keep on ticking (if a ship takes a megaton hit without shields, it is dead, plain and simple) while still taking internal damage for excitement without making up shield bleedthrough or something. You could stick to a plain old power plant and chemical warheads on your anti-ship guns (which I irrationally love) or your fighters. You would avoid the pickle I brought up about huge railgun recoil above entirely.


I think that would be pretty cool.



The Silence and I, I should respond to your latest post tomorrow. It is late and I am tired so I probably won't get to it tonight.

[Hotfoot]

Put it this way, even if the armor itself is not penetrated, the kinetic impact of a multimegaton railgun shell is going to be absorbed by the crew, if the ship is not destroyed, the crew will become a blood mist inside.

Way I read it, Frigid was talking about megaton nukes, not megaton railguns. I'm fine with the former, the latter I have some issues with.

Way I see things, I want to see missiles flying, cannons blasting, etc., so how about this?

Lasers are good for smaller craft. They have decent range and don't have the nasty downside of recoil in space. This is also good for long patrol ships, as it removes specific ammo from the supply line (in lieu of capacitors and such, but oh well). Scaling up the arrays may peter out, since you have to continually pump more power through a smaller aperture. This could mean that lasers are more used as point defense and fighter weapons than as main ship guns, though some races could use them for their big ships. Defenses could include energy shields if we want to go that route, or superconductive armor.

Railguns are a good possibility for heavy firepower. Slower than lasers, but capable of scaling up nicely to larger ships, this could be good mid-level firepower, and so long as we work out an appropriate muzzle velocity, we can get good effective combat ranges. Add to the fact that you can have multiple types of ammo, and you're good to go.

Missles are the longest range and highest firepower option. Realistically, missiles would be the kings of space combat by and large, so I see no reason to end this trend if we want to have missiles. I'm not entirely sold on missile swarms, but here's the thing: we don't need megatons of firepower. There's no need to get into pissing contests for the sake of versus debates. If a 10KT nuke can slag half a ship, that's just fine, especially if we can make it cheap and in bulk.

Let's look at what we want the role of missiles to be. Lasers and railguns are obvious, punch a hole in the enemy ship, do damage to internals, and cause the ship to lose function through loss of the internal systems. The limit of power comes from the limit of power generation aboard the ship. Missiles are big, nasty weapons that can hold warheads in excess of 20 megatons using even modern tech. However, we are still limited by the availability of weapons grade fissionable material. Nukes, while plentiful on Earth at the moment, still have a maximum limit to the number that can ever be created. Ships firing off hundreds of multimegaton nukes in any given engagement would result in some serious degradation of the overall stocks available. Conventional explosives, however, are much more plentiful for obvious reasons.

Now, if we have really good point defense, the smaller, less powerful missile swarms become more viable because the idea would be to overwhelm the defender with numerous, cheaper missiles, but I'm beginning to babble. Anyway, long story short, it would make sense to have some bigger missiles and some smaller ones, but it would help to have a clearer idea on how missiles are intended to be used in combat along with everything else.

Also, I'm not against energy shields at all, but we may want to consider making missiles largely useful for battering down shields at range so that railguns can do their jobs. Or something. You'll have to forgive me, at this point I'm tired and essentially flailing at the keyboard going blah blah blah, so take this all with some kilotons of salt.

[frigidmagi]

Huh Hotfoot, hyperspace is a kiloton environment, so the shields are designed to withstand that. So yeah a megaton nuke would be the easiest way to do it in my opinion.

[Hotfoot]

There's nothing saying we can't lower that value as needed. I honestly don't recall the bit where hyperspace did kilotons of damage when you entered, so that never entered into my mind. Where was that put forward? I mean, if this is the case, the hyperspace relays become much less feasible, since they'd have to have constant refuelings to maintain shields, which of course would be nearly impossible to do with shields up, meaning either armor capable of turning back kiloton level attacks for a prolonged period, or taking the entire array out of hyperspace.