Relativity

Loren Pechtel wrote:Actually, at 0.8c, the Lorentz factor reaches 25 = 1 / (1-0.8²). So the relativistic mass of the missile is 25x its rest mass.

Check your math.[/quote]

Oops. Thanks to you and Robert for pointing out. My intuition was telling me the value was too high but I wasn't seeing where the error was.

Anyway, the formula above was actually correct, it's the calculation I'd made before writing the text that was wrong (I calculated 1/(1-0.8)²). Anyway, the Lorentz factor at 0.8c is only 2.777, so the missile's relativistic mass is comparable to its rest mas, as you'd first said.

My point is: bringing up antimatter here is highly misleading. It could be equivalent to the energy release of a few picograms of antimatter annihilating matter, for all we know.

The mass of the debris in question.

That's not how collisions work. I trust you've played billiards before, or at least seen how it plays out. There's no energy release equivalent to the mass of the colliding objects.

Collision with an active wedge could be something different. We don't know what the formula for that was. But my whole point was that the collision that could disable a missile without obliterating it would be against the body of the missile, not the wedge. Depending on what that piece of debris is, it could punch clean through the missile body and emerge on the other side. The tunnel it bore through the body could be across some critical components.

That's not how I understand them to work. It's not that they can only be fired every .125s, but that that's the average firing rate. As the missiles cross the laser basket in less time than the recharge time each laser gets one shot and that's independent of what the others are doing.

You're probably right, but against a capable opponent, you can't expect them to expend all their shots at long range. If the target is capable enough to pick out real shipkillers from decoys and pen-aids and has a volume of fire sufficient to defend itself, then the volume of fire probably has some left over for anything it couldn't get.

If the ship was overwhelmed in the first place and had to fire everything it had, then some missiles will remain. At that point, they can just fire their warheads. No need to ram.

If they're from one ship they're in one plane.

No, they're not. There's no reason to stay in a single plane, which makes interception easier. Missiles spread themselves in 3D during flight, especially during the final million km, so they can't be targeted from long-range. They have to evade and they have to take all possible vectors, not restrict to to left and right.

They can and should attack from multiple angles, so as to make sure even ships that rotated a little or a lot to interpose the wedge get attacked.

I think you're ascribing more to the missiles than they have. I think they simply detonate as instructed. Once again, we have a situation where the technology changed the battlefield and it wasn't noticed--while some missiles need to detonate at max standoff range you'll be more effective if you let a decent number get closer.

Indeed one of the instructions that the OSO/TAO will do is decide how close the missiles should try to get before attempting to attack. This is done based on prior experience against this type of enemy: their training, their hardware, etc. Missiles can't know that. A solution that would work against the RHN is complete overkill against the SLN: it would make bigger salvos fire from further away, wasting missiles. Conversely, a solution that works against the SLN would fall flat against the RHN: waiting to get too close with too few missiles means they all get intercepted before they fire.

But if you're completely right and the missile simply follows preprogrammed instructions and has nothing close to an AI to make decisions on-the-fly, it would never ram. There's no way the TAO controlling the missiles would know ahead of time that ramming is possible.

I do think they have some intelligence. And the RMN missiles the most/best of all.

ThinksMarkedly wrote:As for ramming an LD, I don't see why it would be more successful than a graser shot from 25000 km away. Remember an LD has no wedge, so it can be successfully attacked from all angles. There's no wedge or sidewall to obscure the position either; its defence is the sheer amount of CM launchers and PDLCs it can have on its huge hull and its stealth. IF the stealth is defeated somehow, the missiles have the upper hand without the need to ram.

Well if the missile survived to bring its wedge into contact with the LD (there's no sidewalls to prevent that) it'd do orders of magnitude more damage than punching a few laserhead holes through the ship. The kinetic energy of the relativistic missile is irrelevant at that point thanks to the destructive power of the wedge.

A single missile wedge can shred half an SD, while you need hundreds of laserhead hits to batter one out of commission.

However the probability of contact may be too low, depending on the LD's point defense, to be worth gambling for - so going for the less damaging but higher probability standoff attacks might still be a far better option.

Jonathan_S wrote:Well if the missile survived to bring its wedge into contact with the LD (there's no sidewalls to prevent that) it'd do orders of magnitude more damage than punching a few laserhead holes through the ship. The kinetic energy of the relativistic missile is irrelevant at that point thanks to the destructive power of the wedge.

I don't agree it's orders of magnitude more. We don't know how wedge annihilation works and, more importantly, we also don't know how wedges and spiders interact. We do know the spiders can be used as very local point-defence mechanisms. But a perfectly-placed graser shot through the reactor cores is very effective.

And if the ship is disabled but doesn't blow up? That's even better. More debris to collect! (see other thread)

Now, if you swap your shipkiller missiles for CM-like ones that don't have warheads but instead attack by using oversized wedges, that's a different story. Since the LD has no wedge, it could be vulnerable to this type of attack. So a long-range swarm of CM-like missiles could be both cheaper and more effective. But this is a different type of missile completely.

However the probability of contact may be too low, depending on the LD's point defense, to be worth gambling for - so going for the less damaging but higher probability standoff attacks might still be a far better option.

That's my argument.

ThinksMarkedly wrote:As for ramming an LD, I don't see why it would be more successful than a graser shot from 25000 km away. Remember an LD has no wedge, so it can be successfully attacked from all angles. There's no wedge or sidewall to obscure the position either; its defence is the sheer amount of CM launchers and PDLCs it can have on its huge hull and its stealth. IF the stealth is defeated somehow, the missiles have the upper hand without the need to ram.

One laser hit with no defenses is nasty but not ship-destroying. One ramming missile will make a fusion bottle explosion look like a toy.

ThinksMarkedly wrote:That's not how collisions work. I trust you've played billiards before, or at least seen how it plays out. There's no energy release equivalent to the mass of the colliding objects.

Collision with an active wedge could be something different. We don't know what the formula for that was. But my whole point was that the collision that could disable a missile without obliterating it would be against the body of the missile, not the wedge. Depending on what that piece of debris is, it could punch clean through the missile body and emerge on the other side. The tunnel it bore through the body could be across some critical components.

You're thinking of low energy collisions. It's not going clean through, it's quickly stopped, liberating vast amounts of energy in the process. (A high speed projectile will be brought to a stop by displacing mass equal to it's own. Going faster doesn't change this.)

You're probably right, but against a capable opponent, you can't expect them to expend all their shots at long range. If the target is capable enough to pick out real shipkillers from decoys and pen-aids and has a volume of fire sufficient to defend itself, then the volume of fire probably has some left over for anything it couldn't get.

If the ship was overwhelmed in the first place and had to fire everything it had, then some missiles will remain. At that point, they can just fire their warheads. No need to ram.

Firing the warhead--damage the ship. Ram--destroy the ship. If the geometry permits it go for the latter option. And if there are lasers left unfired there won't be missiles in a position to make the decision. (Note, however, that having the EW birds ram means the defenders have to shoot them down if they have a ramming solution--once again, degrading their defenses. I don't see ramming as a tactic that will actually be successful, but as a tactic they must degrade their defenses to counter.)

If they're from one ship they're in one plane.

No, they're not. There's no reason to stay in a single plane, which makes interception easier. Missiles spread themselves in 3D during flight, especially during the final million km, so they can't be targeted from long-range. They have to evade and they have to take all possible vectors, not restrict to to left and right.

They'll spread a bit but spreading a lot burns up a lot of delta-v and makes them not time-on-target.

Indeed one of the instructions that the OSO/TAO will do is decide how close the missiles should try to get before attempting to attack. This is done based on prior experience against this type of enemy: their training, their hardware, etc. Missiles can't know that. A solution that would work against the RHN is complete overkill against the SLN: it would make bigger salvos fire from further away, wasting missiles. Conversely, a solution that works against the SLN would fall flat against the RHN: waiting to get too close with too few missiles means they all get intercepted before they fire.

But if you're completely right and the missile simply follows preprogrammed instructions and has nothing close to an AI to make decisions on-the-fly, it would never ram. There's no way the TAO controlling the missiles would know ahead of time that ramming is possible.

I do think they have some intelligence. And the RMN missiles the most/best of all.

The missiles certainly have some local computing--they can watch their target and compute the aiming for the laser rods (which is actually an incredible feat of engineering!!) but evaluating what the defenses are like requires a big-picture view I don't think they can possibly have.

Loren Pechtel wrote:One laser hit with no defenses is nasty but not ship-destroying. One ramming missile will make a fusion bottle explosion look like a toy.

I'll grant you that, especially a wedge-powered missile against a wedge-free target.

But as Jonathan put it, "However the probability of contact may be too low, depending on the LD's point defense, to be worth gambling for - so going for the less damaging but higher probability standoff attacks might still be a far better option."

There's no way to know that except for trying. The MAN might know due to bench testing, but they're not going to publish that to Jayne's. So absent an accidental ramming, I don't see the GA getting sufficient data to conclude ramming is an effective solution in the first place.

At least until they get sufficient pieces of a spider to do their own bench testing. If they then conclude the spiders have no chance against missiles screaming in at 0.85c, they may design a special missile for the specific purpose of killing LDs through wedge contact.

You deploy the bubble. Splat. It's not like you are revealing anything, if some can get a collision course they know exactly where you are.

Loren Pechtel wrote:You're thinking of low energy collisions. It's not going clean through, it's quickly stopped, liberating vast amounts of energy in the process. (A high speed projectile will be brought to a stop by displacing mass equal to it's own. Going faster doesn't change this.)

I think I get what you're saying: the missile added 1.777x its own mass as relativistic kinetic energy and, upon ramming, this energy has to go somewhere. Even if half of the missile does continue through the ship and out the other side, 0.833 times its mass was liberated as energy.

I was thinking of the missile's mass converting to energy, which is not the case. The mass is still there somewhere, in the expanding cloud of plasma. You were talking about the kinetic energy.

Is that it?

(Note, however, that having the EW birds ram means the defenders have to shoot them down if they have a ramming solution--once again, degrading their defenses. I don't see ramming as a tactic that will actually be successful, but as a tactic they must degrade their defenses to counter.)

That I can accept too: manoeuvre to ram, even if the chance of actually getting there is negligible. The target ship can't ignore the threat.

That assumes there's something left of the EW and pen-aid missiles left after executing their functions to actually manoeuvre.

They'll spread a bit but spreading a lot burns up a lot of delta-v and makes them not time-on-target.

Over a 30 to 60 million km run, adding 1000 km separation in a random vector is negligible. In fact, due to imprecisions in each missile's wedge power, it's quite possible that the missiles do already add lateral separation so as to remain T-o-T. A ±0.1% imprecision over 30 million km means missiles are up to 600,000 km away from each other, or 2 light-seconds or 2.4 seconds' flight time. They'd have to get to 10 ppm or less to reduce the interval to 24 ms.

In a missile salvo fired from multiple ships, they probably need to do that anyway, so as to correct for each ship's straight-line distance to the target. So my guess is that this type of correction is built-in.

The advantage is that if they can get 1000 km separation, they can converge on target using a hemispherical spread, instead of just semi-circular. There's no rotation the ship can make that would completely interpose its wedge. If instead they come on a plane, the ship can rotate so the wedge faces the direction of the missiles and the kilt/throat openings are perpendicular to the plane of the missiles. That leaves the sides open for attack as the missiles fly by, but those are protected by sidewalls (whether those are sufficient protection is another story).

The missiles certainly have some local computing--they can watch their target and compute the aiming for the laser rods (which is actually an incredible feat of engineering!!) but evaluating what the defenses are like requires a big-picture view I don't think they can possibly have.

I agree, partially. This is also why I don't think any shipkiller missile would waste a firing opportunity, on the off-chance that the target ship is out of shots and thus unable to intercept a ramming missile. EW and pen-aids is a different story and depends on whether they can still manoeuvre.

But I think they do have some intelligence. That would mostly explain why RMN missiles are so much more lethal, not just from the bigger warhead delivering a stronger graser beam. The war with the SL has shown that the SLN had really poor intercept ratio and I don't think it was just because of Dazzlers and Dragon's Teeth.

ThinksMarkedly wrote:The advantage is that if they can get 1000 km separation, they can converge on target using a hemispherical spread, instead of just semi-circular. There's no rotation the ship can make that would completely interpose its wedge. If instead they come on a plane, the ship can rotate so the wedge faces the direction of the missiles and the kilt/throat openings are perpendicular to the plane of the missiles. That leaves the sides open for attack as the missiles fly by, but those are protected by sidewalls (whether those are sufficient protection is another story).

I don't think they'd go for a fully hemispheric envelopment against ships with a wedge. (They may eventually reprogram missiles to act differently against a spider drive ship).

But against a ship with a wedge a hemispheric attack means guaranteeing a bunch of the missiles have zero chance to engage (which missiles would depend on whether/how it maneuvered). I worked out based on wedge geometry from RFC post over in the pearls than a missile can't have an angle of more then +/- 35 degrees above/below the centerline of the target ship and still have an angle to shoot between the wedge and hit the target.
For RMN missiles with a 50k standoff range than means they can be no more than about 28,000 km above/below that centerline level when they detonate. Anything further up/down will just be firing into the wedge.

(Okay, that's not 100% accurate - the wedge opens steeply enough towards its leading edge that missiles also attacking from somewhat ahead can deviate more in elevation; while those attacking from somewhat behind can deviate less. But I couldn't be bothered to work out the shape of the entire vulnerable zone)

Jonathan_S wrote:But against a ship with a wedge a hemispheric attack means guaranteeing a bunch of the missiles have zero chance to engage (which missiles would depend on whether/how it maneuvered). I worked out based on wedge geometry from RFC post over in the pearls than a missile can't have an angle of more then +/- 35 degrees above/below the centerline of the target ship and still have an angle to shoot between the wedge and hit the target.

Indeed, which is why I think against a capable enemy they have to come in at least an enveloping formation: up, down, left, right, and centre. Better to have some missiles with no chance of striking and some retaining it, than no missiles having a chance aside from through sidewalls.

What's more, Manticoran design philosophy is that they prepare to engage the best. And the best is themselves, who have the ability to rotate and still retain CM capability. So the missiles must have the ability to envelope the target, even if the OSO decides not to use it every time.

For RMN missiles with a 50k standoff range than means they can be no more than about 28,000 km above/below that centerline level when they detonate. Anything further up/down will just be firing into the wedge.

(Okay, that's not 100% accurate - the wedge opens steeply enough towards its leading edge that missiles also attacking from somewhat ahead can deviate more in elevation; while those attacking from somewhat behind can deviate less. But I couldn't be bothered to work out the shape of the entire vulnerable zone)

Indeed, and this is also a reason why ramming is difficult.

In a traditional ship-to-ship engagement, the target ship will either have rotated to present the wedge to the oncoming missiles or to present the broadside it definitely won't present the throat). Against an interposed wedge, the missiles have no chance to ram. Even SDMs would be moving at a quarter light-speed relative to the ship at this point. If the missile is coming at the midpoint of the wedge, using the values from the infodump, the ship will be on average 150 km deep and 115 km from the wedge. That's an angle of 37.5°, which is how much deflection against its baseline of motion the missile would need to achieve.

Against a non-rolled target, still presenting broadside, ramming is possible. And as I was preparing this argument, I realised that an LD lacking a wedge has a major weakness against missiles: the missiles can rotate, pitching up or down, to come at the ship wedge-first. This has two advantages: first, the missile is invulnerable against PDLCs and second, it sweeps a much bigger area. That bigger area helps account for the imprecision on the location of the target ship, due to its stealth.

The two disadvantages are that the missile is blind and coasting, plus it presents a much bigger area for CMs to hit wedge-to-wedge. The solution for that is to make missiles that have wedges as strong as a CM, so it is the one that survives the encounter.

The LD will also want to avoid firing CMs as much as it can, relying on lasers. Lasers can't be seen, unless you're in the direct path of it, at which point you "see" it by blowing up, but that doesn't give a vector to your comrades. But CMs can be seen, so a ship firing missiles with wedges can be pinpointed from a distance, allowing the trailing missiles and the mothership to improve their accuracy.