Newtonian Aurora

[chrislocke2000]

Well, you improved a lot that may come back here, didn't you.
I only fear that NA might turn out to be totally unplayable, what with setting dozen of waypoints to spread out a force of small ship.

Agree this could be a lot of additional management but one that could be quite well managed through a revist of the TG detachments process. Having pre-set formations and spreads could help an awful lot on this.

[Steve Walmsley (OP)]

Well, you improved a lot that may come back here, didn't you.
I only fear that NA might turn out to be totally unplayable, what with setting dozen of waypoints to spread out a force of small ship.

You won't need dozens of waypoints. You can just use the existing escort function. One of the reasons btw that NA uses FTL rather than jump travel is so you don't have to compress formations to enter JPs.

Steve

[swarm_sadist]

...
If you could achieve near parity in numbers, and had an advantage in achieving intercepts, you could win.  But you may still lose economically.  You will likely have to destroy far more of their vessels to equal the loss of just one or two of your battleships.  They will likely be able to replace their losses faster than you also.  If it is a battle for their homeworld, it wouldn't matter.  If this turns into a battle over several systems, battleships might bankrupt you.
...

Not really. A battleship would save you money over time with maintenance (larger ships are historically and intrinsically easier to maintain), and would have a large amount of shields protecting it.

Wars have almost always been decided by who can shoot the farthest and hit what they are aiming at.  May that always be in your favor...

Hence a doctorine of many ships firing from different points and with different course/velocities.  This will rob an opponent of opportunities to manuever that will not be creating high momentum impacts.

Not really. The amount of vectors you would need to be firing from would be prohibitive. Since your trying to hit the target, they would all cross near the target anyways. Plus, a 45-90 degree flank attack would require a lot of fuel. Unless of course you used fighters as the flank attack.

I do see laser and rail guns being assured kills in close.  Lasers will likely have a slight edge, but it will be more of a 'I got to see my weapon destroy my target before his kinetic rounds vaporized me...' sort of edge.  If both sides have them, it will likely be MAD.  Particularly with railguns as both may be able to effectively target all of an opponents ships before their ordinance reaches you.  Hence the doctorine of not putting all your eggs in one basket.  I have a feeling in NA that combat in space will be a lonely thing.  You will be a long ways from anyone friendly as you trade death across the long dark....

While this may be possible in NA, there are many practical reasons why this would never happen. First, the energy required to move an object exponentially increases at relativistic speeds, meaning you would need a more powerful gun. Second, the material's strength determines the maximum pressure you can place upon it from acceleration, capping acceleration. You can of course bypass this by creating larger guns, but then you'll run into the problem of having large capital ships with kilometres of internal spinal mounts. Smaller ships would not be able to have these larger guns and would therefor always be outgunned and outranged. Finally, if you could design a weapon capable of withstanding the extreme heat of a laser, or the pressures involved with railguns, you could make armour out of that same material and get relatively good protection.

According to the Harvard Study On Hypervelocity Impacts From Space Debris, the amount of energy required for catastrophic failure (on a satellite) is about 10,000 Mt Joules, with Mt being mass of target in kilograms. A 2.8 ton satellite requires 28 MJ of energy for catastrophic failure (this is dependent on impact angle, with anything over ~30% drastically spreading the damage out. While this only deals with small objects like satellites, it basically means that MAD outcomes will be doubtful, unless the math is simplified to k=1/2mv^2. An armoured battleship would be able to shrug off anything lower than battleship sized weapons, and probably 6-10 rounds of railguns.

[jseah]

According to the Harvard Study On Hypervelocity Impacts From Space Debris, the amount of energy required for catastrophic failure (on a satellite) is about 10,000 Mt Joules, with Mt being mass of target in kilograms. A 2.8 ton satellite requires 28 MJ of energy for catastrophic failure (this is dependent on impact angle, with anything over ~30% drastically spreading the damage out. While this only deals with small objects like satellites, it basically means that MAD outcomes will be doubtful, unless the math is simplified to k=1/2mv^2. An armoured battleship would be able to shrug off anything lower than battleship sized weapons, and probably 6-10 rounds of railguns.

Some time earlier...

Are you forgetting that ship speeds are on the order of a thousand km per second or so?
Even plasma is not particularly healthy, with armour at 100s of MJ and shells starting at GJ all the way up to TJ ranges. 

A projectile vapourizing on your whipple shield is like a nuke going off right next to you.  And we all know what happens when one does that. 

[procyon]

Not really. A battleship would save you money over time with maintenance (larger ships are historically and intrinsically easier to maintain), and would have a large amount of shields protecting it.

Problem is, your battleships with a lot of expensive systems/munitions/fuel can still be destroyed by a single nuke from a cheap 'figher/FAC'.  You will have to destroy many of the attackers, where as only one of them has to get lucky.

Not really. The amount of vectors you would need to be firing from would be prohibitive. Since your trying to hit the target, they would all cross near the target anyways. Plus, a 45-90 degree flank attack would require a lot of fuel. Unless of course you used fighters as the flank attack.

I don't think you are grasping the concept.

You won't be facing a fleet all coming from a single point with a single vector that then tries to break up and manuever.
You will be facing a group that starts in a wide variety of locations.  As an example deployment in Sol -  A couple around Earth's orbit.  More stationed in the Jovian/Trojans.  More from Neptune/trans Neptune.   All set on differing points in the orbits/vectors.  The shots/missiles coming at you will be originating from a large number of angles.  Manuevering in any direction to avoid some will increase your closing speed with others.  Unless you are coming in from way out system you will not be able to keep them from closing off your available vectors of manuever.  And if I can limit your manuever options, you are going to end up becoming a simpler target to fix/destroy.

While this may be possible in NA, there are many practical reasons why this would never happen. First, the energy required to move an object exponentially increases at relativistic speeds, meaning you would need a more powerful gun. Second, the material's strength determines the maximum pressure you can place upon it from acceleration, capping acceleration. You can of course bypass this by creating larger guns, but then you'll run into the problem of having large capital ships with kilometres of internal spinal mounts. Smaller ships would not be able to have these larger guns and would therefor always be outgunned and outranged. Finally, if you could design a weapon capable of withstanding the extreme heat of a laser, or the pressures involved with railguns, you could make armour out of that same material and get relatively good protection.

We have already discussed at length the issues with what it will take for a material to survive the posited rail guns.  I was/am a big opponent of any guided rail munitions due to the stress involved in firing.  I'm not going to rehash that.  
And for the 'if it can survive launch, it makes great armor' thought, this can be true - to a point.  But modern materials used in cannons, etc can withstand firing and when used as armor tend to fail against a weapon made with the same materials given sufficient energy.  In fact they fail against materials of lesser integrety with adequate energy involved.  Copper penetrators do a fine job punching through our tanks overseas...

According to the Harvard Study On Hypervelocity Impacts From Space Debris, the amount of energy required for catastrophic failure (on a satellite) is about 10,000 Mt Joules, with Mt being mass of target in kilograms. A 2.8 ton satellite requires 28 MJ of energy for catastrophic failure (this is dependent on impact angle, with anything over ~30% drastically spreading the damage out. While this only deals with small objects like satellites, it basically means that MAD outcomes will be doubtful, unless the math is simplified to k=1/2mv^2. An armoured battleship would be able to shrug off anything lower than battleship sized weapons, and probably 6-10 rounds of railguns.

jseah already adequately dispelled this issue...

[swarm_sadist]

PART ONE: SHIPS' WEAPON SYSTEMS IN THE TERAJOULES RANGE
Well let's figure this out. A 30.0 kg projectile will be fired at a velocity of 570,000m/s, giving a muzzle energy of (Ek=0.5mv^2) Ek=0.5(30.0)(570000)^2=4.8735E12 Joules, or 4.87 TJ. This I figure is a nice TJ number for this thought exercise. First off, we need to figure out the maximum acceleration of the round, the distance of the barrel, the power requirements and the rate of fire.

We need to figure out how fast a round may be fired out of a railgun. If the initial velocity is 0 m/s and the final velocity is 5.7E5 m/s, then we can find the length of the barrel. Distance round must travel is equal to (final velocity minus initial velocity divided by 2) times the duration of acceleration. Now we need the time in the barrel.

Time in barrel is equal to final velocity divided by acceleration. Now we require acceleration. We shall use F=mass*acceleration. F=30kg*m/s-2. Using the pressure formula (Pressure=Force/Area) and the force formula, we get (Pressure=(mass * metres)/(Area * seconds^2)). Steve says that 10m^3 = 1 ton, so 0.03kg * 10 = 0.3m^3. Cube root that and you get 0.66943295 metres. Assuming a square round, the area of one side is 0.448140475m^2. Now we have area and mass, but require pressure to get the final acceleration. For this I will use adamantine (5GPa) and assume that the gun will fire the round at maximum pressure. (5E9 Pa * ~0.45 m^2) / 30.0 Kg = 74,690,000 m/s-2. With final velocity (570,000m/s) divided by acceleration (~75,000 km/s^2), we get 0.007631536 seconds in the barrel.

With the final velocity (570,000m/s) averaged against the initial velocity (0 m/s), we get (285000m/s) times the time in the barrel, we get a 2,175 metre long barrel. The length of the barrel seems reasonable, as does the time in barrel and acceleration. A spinal mount can be mounted inside a ship the size of a star destroyer fairly easily, and most spinal mounts in different universes can take up 40-85% of the ships length. With tempered steel today reaching ~2GPa with special treatment, I think this is reasonable as well.

Now this is where things start to go bad for Terajoule weapons. Steve's rules show a MJ to ton constant for weapons, with what I think is TL4 being 12 MJ/Ton. This would make the 4.87 TJ gun have a mass of 406,125 Tonnes at TL4 [1]. The power requirement would be 4.87 TJ / Efficiency. With Steve's listed 35% (which I'm guessing is TL2), the gun would require 13.9 TJ of energy to fire.

The rate of fire is dependant upon the radius of the gun compared to it's mass, and the heat dissipation rate (we shall assume TL5? 0.6 MJ/s per m^2 of surface area. If the gun has a mass of 4.06E5 Tonnes, then the volume is [2] 40,613 metres cubed. If this is a circle, then the radius would be (3*40613/(4*pi))^(1/3)=21.323516207 metres. The surface area would be area = 4 * pi * 21.32^2 = 5714 metres squared. The gun may radiate 5714 * 0.6 = 3428 MJ of heat a second. This gives a fire rate of 4870000 MJ/ 3428 MJ/s = 1420.65 seconds, or ~23 minutes. [3]

For smegs and giggles, if the gun were counted as a cylinder instead of a circle, with the gun length being 2175 metres long. We already calculated the bore to be 0.67 metres in diameter, so we can estimate the size and mass of the gun itself (and not the power capacitors, wiring, etc) as 3067 metres cubed and 30,673 tonnes respectively (lol, 7.5% gun). The surface area is 9159 metres squared, giving a heat lose and fire rate of 5495.4 MJ and 886.20 seconds, respectively. This could be further enhanced by the volume to surface area ratio, taking into effect the conduction of heat through the material being faster. The sphere is ~0.14 surface/volume, while the cylinder is ~2.99 surface/volume. You of course then have to worry about the mass ratio getting out of control as you try to increase surface area (length) while decreasing volume (bore). I just find the ~15 minute firing time to be more reasonable, so ignore this whole section if you want.

Power requirements to power a gun in 1420.65 or 886.20 seconds will require a reactor capable of producing 9.8 GW or 15.7 GW of power for the entire recharge cycle. As I don't know how much energy sorium has, I'm not sure if this is a good number to go by or not. If you compare the total power when dealing with heat radiating(IE factor in efficiency for recharge time), then you get a recharge time of 4059.01 seconds.[3]

CONCLUSION:
-That weapons in the TJ range will be useless except for late game, and will always be more inefficient than a bunch of smaller guns.
-That the range you gain will limit your ability to fight multiple attackers, and make misses more deadly for you.
-That larger ships will be the only ones capable of fielding GJ weapons until far later in the game.
-That Steve's designs hint at high MJ to low GJ range for basic ship armaments.
-That efficiency will make or break your design.
-That DPS through high rate of fire may be more useful than fielding large, ship killing weapons.
-That a person with no social life will find errors in anything.

Also, since all the shield tech seem to line up with weapon tech, a ship capable of fielding a 400,000 ton railgun will certainly be able to equipped a large amount of shields to go with it, as well as smaller cannons around itself.

[1] Does the initial tech level count as TL1 or TL0?
[2] Hull section says 10 tonnes per cubic metre, weapons section says 1 ton per cubic metre???
[3] Shouldn't fire rate use the total power required instead of muzzle energy? Doesn't the inefficiency of the gun count as HEAT?!?

Yes, I kind of just proved my point on no instant kill weapons while at the same time disproving the use of battleships in space combat.

#I understand that if I worked backwards from the volume and mass to get pressure and gun length that I would have gotten a more accurate answer. I also apologize in advanced to errors, as it is 11:00pm local time on a weekday. I also understand I choose a rather poor level in efficiency, but that was the only example I could find in the same section.

Part two, attacks from multiple vectors and the myth of envelopment in space, even if space is 2D. I'm doing this one tomorrow though as I am very tired.

[jseah]

It has nothing to do with the speed of the launch and everything to do with the speed of the ship. 

Again, I quote:

Are you forgetting that ship speeds are on the order of a thousand km per second or so?

Emphasis mine. 

The idea was to mount a railgun with 10-100km/s muzzle velocity (MJ range), onto a ship with ~30 000km/s total delta-v.  With some leftover for maneuvering and depending on tactical situation, ship closing speeds could vary from nearly 0 to over 10 000km/s. 
I'm sure you could do the equations for a 1kg ball of metal flying at 5kkm/s?

And this sort of delta-v is around the tech level of the example ships posted.  Aka. quite early indeed. 

With widely spaced attack and defence groups, ala the situation described by Procyon, it will be impossible to be "at rest" relative to all groups.  You will have high relative velocity to some groups, and that is enough to kill you. 

Fragmentation missles are the same, but worse.  Missiles have 4x the delta-v of ships for the same fuel since they aren't going to slow down (although they are less efficient, so it's not quite 4x).  Their speed and accel will always be higher than any ship can feasibly acheive, given roughly similar tech levels, and even standard overtaking speeds will be on the order of thousands of km/s relative. 



You don't need to have a big ass railgun to dump rocks out the hatch.  And yes, yes, rocks WILL kill you when they are going that fast. 

[swarm_sadist]

Let us consider two ships of the same design. 2000 tons total, 6 layers of armour, using the example weapon and engines. For this we shall consider the ship to have unlimited range against static or predictable opponents and will always hit.

The ship will look like:
Example ship
2,214 tons
Acceleration: 6.78 m*s-2 (0.69g)
Armor 6cm/70 (125 MJ per cm)
Maximum Shield Strength: 24,000 MJ
Point Shield Strength: 1,144 MJ

Magneto-plasma Drive
Thrust: 12.5 MN     Base Fuel Consumption per MN: 188.1 litres per hour
Base Acceleration: 50 mp/s (5.1G)
Fuel Use at Full Burn: 2351 litres per hour
Engine Size: 250 Tons    Engine HTK: 2
Thermal Signature: 125     Exp Chance: 12
Cost: 62.5    Crew: 8
Materials Required: 15.625x Duranium  46.875x Gallicite
Development Cost for Project: 625RP

2x 2400 MJ Railgun
Muzzle Energy: 2400 MJ     Muzzle Velocity 69,282 m/s    Cooldown Period: 24 seconds
Power Requirement per shot: 6,857 MJ    Energy Efficiency: 35%
Mass Ratio: 200k    Energy Efficiency Penalty: 0%
Railgun Size: 200 tons    Surface Area: 165.4    Projectile Mass: 1 kg
Cost: 24    Crew: 20    HTK: 2
Materials Required: 24x Vendarite
Development Cost for Project: 240RP

Shield Generator
Size: 200 tons HTK:2 <-I just guessed with that.
MJ/T: 100 MJ/T (20,000MJ) +20% (24,000 MJ)
Recharge Rate per ton: 0.25 MJ/s per ton (50MJ/s) [1]
Point strength: (200/4194)*24,000=1144 MJ/200m^2

We shall also assume 40% fuel, 10% crew, bridge, etc and 150 tons of fire control and reactors. HTK 31 in total, if fuel is armoured. Otherwise, 15.

We shall also assume there are four types of damage being inflicted: No damage, light damage, mission destruction and total destruction. Total destruction only occurs when an explosion happens, or if all crew members were killed.

Damage: 2400 MJ - 1140 MJ = 1260 MJ - 750 MJ = 510 MJ. Since the diameter of the ship before armour is 34m and the armour section has a size of 10m^2, I shall consider the area damaged as 340m^3 out of a total of 20,000m^3 before armour. A total area of 1.7% of the ship is damaged. My guess is that the round would find nothing powerful enough to fully stop it, and would continue out the other side of the ship. Since I have no idea how Steve is handling internal damage, I shall give my own idea.

First idea, mass provides the chance that a component will be hit. Since the engine takes up 12.5% of internal mass, and it's the only component that can explode#1#, I'll look at that first. Each m^3 of damage has a power of 1.5 MJ. Since the lowest sized component on this ship is 50 tons, that means that each component has a minimum size of 500m^3. The largest size, the fuel tanks has 800 tons (8,000m^3). The engine is 2,500m^3, so only 13.6% of the engine room would be effected.

The chances of the engines being hit is 12.5%, the chance of hitting something vital (HTK) I shall assume has something to do with how much area is effected. There is a 13.6% chance for one of the HTK being hit, and a 1.8% chance of both being hit. Each HTK gives a 12% chance to explode (which I assume would be a critical death), so both being hit results in 24% chance of total death. Both exploding gives a 1.4% chance. In total, the chance of an instant death is 0.2%, per hit. This does not include chance to hit.

This is also assuming the round would remain intact and continue through the ship. If the round detonated into plasma, then you could simply keep the armour layers a few centimetres apart to reduce the damage sustained over a large amount of empty space.

This is not even considering evasion, interception or retaliation. The amount of damage possible against a ship will be dependent upon the amount of energy that can be transfered to it's surroundings. A penetrator will be best at moving through defences, but will also penetrate the area it must damage as well. An explosive or round designed to fragment into shrapnel or plasma will do great against internal sections, but would spread it's damage out over a larger shield/armour section. You would also have to take into account plasma cooling over the layers of armour, and heat conduction through the metal of the ship, which would both reduce the final energy that reaches the ship systems.

[1] Would the size efficiency help shield recharge rates as well?

Edit:
#1#Yes, I noticed I have a reactor in there that may explode as well, but since I don't have a reactor example in NA:Rules, I have left that out. There would be 2 reactors with a total of 100 tons in this design, with an Explosion chance of 5% each (I would guess), if anyone wants to figure it out.

[jseah]

Take your example ship. 

2214 tons dry weight
40% fuel = 3690 full load = 1476 tons fuel = 1 476 000 litres
Total burn time assuming 1 engine: 7847 (0d.p.) hours = 28 248 803 s (0d.p.)

Max delta-v assuming pushing full load (I'm lazy and it errs on the low side, consider the excess lost to evasive maneuvers): 95 693 (0d.p.) km / s

Take 1/20th delta-v as standard combat velocity: 4784 km / s (0d.p.) combat speed
Railgun muzzle velocity as portion of combat velocity: 1.4%


Assuming our enthusiastic Kapitan decides to do a demonstration strike on the moon, we can expect a railgun round to travel at 4784 km / s. 

Projectile mass: 1kg
Projectile kinetic energy: 11 TJ (2s.f.)
 - Wikipedia tells me this is about 1/6th the yield of the hiroshima nuke

The moon gains a new crater that astronomical enthusiasts can spot with a telescope. 


In other news, an unwary patrol frigate is caught by a swashbuckling pirate who decides to fire a "shot across his bow".  The gunner misaims and hits the ship instead. 
Shields - 20GJ
Armour - 70 x 6 x 125 MJ = 52.5 GJ

The "warning shot" blows down all the shields, all the armour, and is still has 11 TJ left to go (decimals absorbed the rest...)

The shell will almost certainly vapourize upon contacting the shield or armour.  The expanding ball of plasma blows a hole in the armour and proceeds to knock a hole all the way out the other side of the ship.  Assuming the projectile leaves only 1% of it's energy on the ship, that's still enough to vapourize everyone on board. 

EDIT:
In practice, the pirate or Kapitan won't be getting perfect delta-v shots.  The actual damage will swing widely from twice the speed (4x the power) to something like your scenario, depending on the geometry of the combat. 

[swarm_sadist]

The easiest way to remedy that situation is to create a cage armour around the ship, which would therefor make the round expand into a spray of plasma early. Or, you could fire a small round at the round. If the round is turned to plasma far enough away, then the shields can absorb most of the damage. After all, the plasma will lose energy exponentially the farther away it is. My guess is a CIWS that shoots at targets 1-10km away would work perfectly. Another problem is that, because the round is exploding instead of penetrating, the explosion would radiate in all directions, not only against the ship. A shield would more than likely reflect most of the damage away from the ship, if that were simulated. After all, a nuclear resistant armour is not new. The Orion drive was designed to survive multiple nuclear blasts near it.

While yes, the velocity of the railgun is only a small part of the velocity you can achieve, there is the small problem of not being able to fire, except for a very limited arc. The round maintains the momentum and velocity it was traveling, +/- the railgun's launch velocity. If you needed to shoot behind you or to the side, you would not be able to hit anything.

While a railgun shot at high speed is great, it wont work against a moving target. A target that sees you can simply veer lazily at an AOB of 90 or 270. At high speed the attacking ship would not be able to change the momentum of the ship fast enough. Not only that, but now the defending ship can fire a round or two in the direction of the attacker, and that round will have the same amount of damage as the attacker's.

Finally, I have my doubts that the round would continue going if it detonated into plasma. Either it penetrates or detonates, it can't do both without major changes to physics.

[jseah]

My guess is a CIWS that shoots at targets 1-10km away would work perfectly.

This would work.  The others... not.  Anything that makes the projectile explode closer than one to two hundred meters or so will not work, the dispersed plasma still all hits your ship and your ship still explodes.  At higher tech levels, this can maybe go to a full km. 

The problem with CIWS comes with fragmentation missiles which split into hundreds of projectiles, each with higher relative velocity and higher weight than a standard railgun round.  Can't get them all. 

The question of whether the round goes through the ship or not is academic.  It has TJ range energy.  Your ship is dead. 

While a railgun shot at high speed is great, it wont work against a moving target. A target that sees you can simply veer lazily at an AOB of 90 or 270. At high speed the attacking ship would not be able to change the momentum of the ship fast enough.

It will work.  Assuming the approaching ship has already achieved a lethal velocity, all it has to do is match the fleeing ship's accelerations and then net change to relative velocity is zero.  If your target is in your firing arc... well then! 

A missile will have necessarily higher accel than a ship.  In which case, a ship can never escape a fragmentation missile's cone of debris, plus the missile still gets to evade and still gets to gain delta-v. 

Of course, accelerating on a closing vector at any distance will be treated as hostile act, for this very reason. 
EDIT: obviously, I don't mean that all the time.  Good reasons exist for closing vectors.  But meeting an unknown ship out in the darkness?  If it turns to chase you, it's probably hostile. 

[swarm_sadist]

This would work.  The others... not.  Anything that makes the projectile explode closer than one to two hundred meters or so will not work, the dispersed plasma still all hits your ship and your ship still explodes.  At higher tech levels, this can maybe go to a full km. 

The problem with CIWS comes with fragmentation missiles which split into hundreds of projectiles, each with higher relative velocity and higher weight than a standard railgun round.  Can't get them all. 

If the projectiles can be considered like shrapnel or space caltrops, then we can view the missile as a dispersion machine. At these speeds your talking about, the dispersion would have to be from far away or very fast. If fast, then explosives must be used to separate the missile and fragments apart, thus reducing some of the mass (and kinetic energy) before even reaching the target. If done from far away, then the fragments will be spread out more and will be like micrometeorite impacts, which I'm sure something like a spaceship would be able to defend itself against. There is always some cost and con to every weapon system.

The question of whether the round goes through the ship or not is academic.  It has TJ range energy.  Your ship is dead. 
It will work.  Assuming the approaching ship has already achieved a lethal velocity, all it has to do is match the fleeing ship's accelerations and then net change to relative velocity is zero.  If your target is in your firing arc... well then! 

Would it be effective against armour? Yes. Would it destroy the ship? Probably. Would it be cool? Yep. Would the ship exploded into fiery bits? The universe loves to disappoint people. And your firing arc in your example is +/- 0.83 degrees.

I suppose the question to ask is what happens at contact to the round? Will it: remain intact, break into fragments, turn into molten shards, turn into plasma or vaporize. In that order, the density of the energy decreases to the point of you being able to resist it with ablative armour. If it remains intact, unlikely at 5000k km/s, then the round would make a big hole in the armour, go in a straight line through the ship and come out the other side. I doubt it would pass any more energy to the ship besides the energy required to get through the armour, although the molten bits of armour would continue with the round and exit out the other side.

Again, not as awesome as the round leaving a trail of space debris into the next ship, but the universe does have rules in place that prevent ever increasing energy. Eventually you'll reach a point where more energy and more velocity is a bad thing.

A missile will have necessarily higher accel than a ship.  In which case, a ship can never escape a fragmentation missile's cone of debris, plus the missile still gets to evade and still gets to gain delta-v. 

Of course, accelerating on a closing vector at any distance will be treated as hostile act, for this very reason. 
EDIT: obviously, I don't mean that all the time.  Good reasons exist for closing vectors.  But meeting an unknown ship out in the darkness?  If it turns to chase you, it's probably hostile. 

Well you don't start evading when the missile has exploded, you start evading the instant the guy fires. If you can make him miss, you just have to turn opposite his movement and start speeding up. He'll overshoot you before he gets a chance to fire another shot and will take him hours to days to change direction and follow.

[UnLimiTeD]

That is interestingly enough the point.
Kinetic rounds will be fatal, but extremely hard to hit with.
Maximum accuracy at long ranges is probably up to missiles, preferable fragmentation mirvs and Laser Rod Warheads.

I recommend this thread for more info, especially the Article about the ravioli.

[jseah]

If the projectiles can be considered like shrapnel or space caltrops, then we can view the missile as a dispersion machine. At these speeds your talking about, the dispersion would have to be from far away or very fast. If fast, then explosives must be used to separate the missile and fragments apart, thus reducing some of the mass (and kinetic energy) before even reaching the target. If done from far away, then the fragments will be spread out more and will be like micrometeorite impacts, which I'm sure something like a spaceship would be able to defend itself against. There is always some cost and con to every weapon system.

I was thinking something like a 5 ton missile (same tech level as your proposed ship), max accel 10 times of the ship, max delta-v around 1/10th to 1/20th of the ship's.  It's about 70% fuel (technically, for best energy, the fuel fraction should be 2.71 times of the warhead). 
Plus, the missile STILL gets the firing ships' velocity (ala railgun), and still gets to accelerate even more. 

The 1.5 ton warhead then separates into 500 chunks ranging from 1 to 5 kg each.  Say 20% is in the separation charge. 

That's not micrometeorite impacts.  A 1 gram chunk at 10kkm/s?  Ok, your ship can survive that.  1 kg?  No way. 

Even if the chunk plasmarizes on your shield, the plasma ball contains the same momentum it originally did.  If it doesn't get to spread out enough, and a hundred meters isn't enough at the speed its going at, your ship is dead. 
Sure, every panel of armour takes less damage, the density of the energy decreases.  But when 1% of the chunk has enough energy to vapourize ALL your armour, that doesn't help at all.  Those armour columns are going to receive a hundred GJ in plasma, each. 


Furthermore, whether you can generate a miss from a missile fired within it's powered envelope (the max distance the missile can travel at full burn) can be calculated.  In the standard case of a ship firing a missile at a target somewhere in front of it (front being the direction the ship is moving in), the target ship cannot make it miss. 
The missile has higher accel than ships, thus it matches the ship's accel and uses the excess to build delta-v or course correct.  This makes missiles have ridiculous firing arcs compared to railguns, especially since a 2.71 fuel ratio missile will have a long burn and massive powered envelope. 

[procyon]

I like the discussion.
This is why I love NA.  People actually have to think in real term.  Not just rule lawyering to try and come up with a good design in a game.

If the projectiles can be considered like shrapnel or space caltrops, then we can view the missile as a dispersion machine. At these speeds your talking about, the dispersion would have to be from far away or very fast. If fast, then explosives must be used to separate the missile and fragments apart,

Nope, no explosives.  Bad idea.  Poor ability to get even predictable dispertion.
If it is designed as a 'shrapnel missile', it has some lateral thrusters able to induce a degree of spin.  It can build this up and then release the preformed fragments to disperse at an easily calculated rate to acheive a set level of saturation on target.  This is already done in several current weapon designs.

Would it be effective against armour? Yes. Would it destroy the ship? Probably. Would it be cool? Yep. Would the ship exploded into fiery bits?

I don't care what victory looks like, smells like, tastes like.
It is victory.

Well you don't start evading when the missile has exploded, you start evading the instant the guy fires. If you can make him miss, you just have to turn opposite his movement and start speeding up. He'll overshoot you before he gets a chance to fire another shot and will take him hours to days to change direction and follow.

Furthermore, whether you can generate a miss from a missile fired within it's powered envelope (the max distance the missile can travel at full burn) can be calculated.  In the standard case of a ship firing a missile at a target somewhere in front of it (front being the direction the ship is moving in), the target ship cannot make it miss.  

This pretty much is drifting in the direction I did months ago.
Kinetic kill.  Needs saturation and predictable target trajectory.
Guided kill.  Needs target defense saturation or fractional engagement times.

Hence why I think a small ship (your huge cage or shields out a long distance from a ship just provides more area to catch bad things...) with a kinetic kill weapon (rail gun or like) with fair ROF and high ordinance carried paired with a few guided weapons (missile with nuke/lase/shrapnel payloads) in dispersed formations.

Those railguns may have a hard time tagging you with individual shots, but several closing from differing vectors may give you little room to manuever.  Depending on how well you can resolve the slugs on your sensors, you may not be able to see them until it is too late.  If your CIWS only has an engagement range of 10km, on a slug closing at 4000km/s, well - you have .0025 seconds to stop it.  Hope there isn't more than one at a time....
Add in missiles and your manuever options may get worse.  A number closing on you that you are manuevering against may chase you right into the railgun rounds you can't see coming.  I also expect single ships to make multiple vector missile courses simply by manueuvering.  No 'launch all at once'.
Launch one with excessive velocity that will overshoot on a wide course and then come back from the far side of a target.  A second with a course to more directly approach a target.  A third targetted to make a particular vector hazardous should the target decide to manuever that direction.
Saturate escape vectors with rail gun rounds.

Now put this all coming in from three or four (or more) different sources, each with several missiles closing on different trajectories, with a minefield of rail gun rounds dispersed within it.

I forsee the player best able to master this as the winner.

I have also stated, and believe, that if the tech allows you to track target ships at interplanetary distances, and the game will track the projectiles over that range, that this is the range these battles will be fought at.  With ships firing from Earth, Jupiter, and Saturn on a target near Mars as an example.  And manuevering against the same problem.

I anticipate lots of caffeine, incredible headaches, terrible frustration with a computer that seems to crawl towards a resolution - and amazing fun !

But until the game actually comes out, it is all just a guess.
But with ships moving at 1000s of km/s speeds, a 1kg chunk of anything is death.
The best defense will be the same as it is now in a gun fight.

DON'T GET HIT.


 


EDIT

I also love seeing people go through the math you did Sw Sad.  Reaffirms my belief that not all folks out there have been swallowed up by video games.
I did the same thing (in a different vein) many pages back in this thread, but came at it from the G's induced by firing and the bearing strength of materials to show that a rail gun slug would become anything but a lump (at best).  Guided railgun rounds even at MJ ranges without ships at least half a klick in length just aren't going to be anything but a crushed molten mass.
I also debated induced occilation/maximum achievable accuracy in the barrel of a rail gun when the possibility of firing 'planetkillers' at Earth from Neptune or past orbits.  Your huge rail gun would be worthless as a ship to ship weapon.    But if you jump in far enough out that hostile weapons may need days to reach you, that 23 minutes (or even an hour) per shot will still give your massive ship a LOT of time to dump death on a world before it turns and jumps out.