Relativity

It makes no sense to be firing missiles if you have not localized the spider. They have terrible sensors and space is very very big.

kzt wrote:It makes no sense to be firing missiles if you have not localized the spider. They have terrible sensors and space is very very big.

You must have at least a rough idea of where it is. How rough will depend on what your missiles can do when they arrive nearby.

ThinksMarkedly wrote:

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.

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.

Your equation is INCORRECT, see http://hyperphysics.phy-astr.gsu.edu/hb ... trans.html . Thus the factor, at .8c, is the inverse of .6 rather than the inverse of .36.

Note:
I first opened this can of worms about ramming in the Battle of Spindle thread. There is an appalling number of MK23-E control missiles wasted per massive launch.

Somewhere over in the thread, the .8c rad-shield limitation imposed on a missile's accel is the impetus behind my conception of a MAN missile using a different design which allows it to use 100% of its missile's accel. I called it a burst mode. Since the MA will be potentially launching from very short, unprecedented distances then they should be able to guide the missile to it's target without the need to expose it's sensors. Indeed, without the need for the missile to even rely on sensors. Because the LD is so close, it can guide the missile to it's target, thus, also circumventing light speed limitations. Even if traditional missiles are launched from RF ships at maximum range it can pass control to the much closer LD.

That is the logic behind my post anyway, whether it has merit or not.

The notion about using the many orphaned control missiles to ram an LD is confined to any situation which becomes one of Providence where the possibility simply happens to present itself. Like the rare chance Scotty was presented opportunity to sneak in a nuke. Or out of necessity, like if the last remaining launch is headed downstream when the location of the LD becomes known.

Also related to that notion is the reality that an LD has to be concerned with occluding stars. Well, the 23E's are sharing snapshots of the battle field, and they're already using insanely capable computers. If they can analyze all of their views of the heavens, the proper algorithm may be able to detect missing stars, in their FOV. (Field of View)

ThinksMarkedly wrote:

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.

Even without a wedge the impact will destroy the ship. And note that to save the ship the point defense must actually shove the missile aside somehow, merely "destroying" it isn't enough unless they can zig out of the way of the plasma cloud it left behind. That plasma cloud will be just about as deadly as the intact missile.

ThinksMarkedly wrote:

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.

If part of the missile goes on through it's kinetic energy isn't liberated. I'm talking about that kinetic energy of whatever is stopped (and I think that will be the whole missile, especially if it can do something like turn sideways before impact.)

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?

Yup. The kinetic energy at MDM burnout is similar to the rest mass of the missile. The biggest booms we have seen were in the low gigatons. A missile ram exceeds a teraton.

(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.

There is--the dazzlers are spent as they enter the defense zone, but they soak up defensive shots anyway.

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.

But said 1000km spread when they are engaging from 50,000km away still puts them in a very narrow piece of the sky. All are coming in at just about the same angle.

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.

But fleets stay close together so their defenses cover each other.

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.

It's not an off chance--it's quite likely. If the defender still has shots left the missile wouldn't have been allowed to reach detonation range. The fact that it is there at all either means the defenses are dry or that multiple shots have missed.

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.

The SLN also has the problem that none of it's defenses were engineered to deal with missiles with that kind of closing velocity. I don't think there's anything a missile realistically can do to avoid being shot down, but a better seeker is less likely to be spoofed.

Robert_A_Woodward wrote:Your equation is INCORRECT, see http://hyperphysics.phy-astr.gsu.edu/hb ... trans.html . Thus the factor, at .8c, is the inverse of .6 rather than the inverse of .36.

Gah, sorry, the radical disappeared from the text. I made two mistakes then. Should've just written "sqrt."

I'm going to sit in a corner for a while so you don't take my nerd membership card away.

The analysis is valid, though off by a factor of 2 to 3.

cthia wrote:Somewhere over in the thread, the .8c rad-shield limitation imposed on a missile's accel is the impetus behind my conception of a MAN missile using a different design which allows it to use 100% of its missile's accel.

That sentence makes no physical sense. The 0.8 or 0.9c limitation of the particle shields applies to top speed, not accel. It doesn't matter how fast you get to that speed, you can't pass it.

Are you proposing an acceleration mode that burns the impeller in less than 60 seconds, but achieves much more acceleration? Say, 200,000 gravities? I remember this part of the thread, and my arguments is that it's not fast enough, unless said missile can achieve ludicrous speeds.

I called it a burst mode. Since the MA will be potentially launching from very short, unprecedented distances then they should be able to guide the missile to it's target without the need to expose it's sensors. Indeed, without the need for the missile to even rely on sensors. Because the LD is so close, it can guide the missile to it's target, thus, also circumventing light speed limitations. Even if traditional missiles are launched from RF ships at maximum range it can pass control to the much closer LD.

That short range is not less than 1 light-second. Even then it would be dangerously close to an enemy with good sensors or any formation of ships where you couldn't take all of them out in one shot.

At 2 light-seconds away, a missile accelerating at 200,000 gravities would need 12 seconds to strike. At 300k gravities, it's still 10 seconds. To get it under 5 seconds, you need more than 1.2 million gravities, which is 10x more than the the current fastest CM missile known. And it is moving at only 0.2c at the end of this run.

And without sensors? Do you expect the missile to fly in a straight line, like a beam? That makes interception far easier.

And why would the MAN use FTL for this? Note that even the state-of-the-art RMN requires a missile dedicated to being the FTL platform. Even if the MAN can replicate the technology and miniaturise it sufficiently to fit in a missile body, they'd still have to do something like Apollo and send a control missile for every N shipkillers, and all this would achieve is reduce the control loop from 6 seconds to 2.06 (the baseline 2 seconds is the time lag of the sensors). They would need not only an Apollo, but also a Ghost Rider, with sufficient stealth to get much closer than 1 light-second.

Summarising, you're positing that the MAlign achieves:

• An acceleration breakthrough of about 10x
• Sufficiently miniaturised FTL comms to fit a drone and a missile
• Stealth that would allow the drone to close to less than 150,000 km of RMN ships

And all of this still assumes that the LD can generate an intercept course with its targets. I've said this time and again: aside from a fixed location where the ships must go to, that's nearly impossible for ships that are slower than their targets. And for fixed locations, there'll be active radar and ready defences.

Also related to that notion is the reality that an LD has to be concerned with occluding stars. Well, the 23E's are sharing snapshots of the battle field, and they're already using insanely capable computers. If they can analyze all of their views of the heavens, the proper algorithm may be able to detect missing stars, in their FOV. (Field of View)

The sky isn't filled with stars; there's a lot of empty space, or at least where the background object being occluded is sufficiently faint that missiles and ships would not be carrying instruments to detect them.

cthia wrote:Somewhere over in the thread, the .8c rad-shield limitation imposed on a missile's accel is the impetus behind my conception of a MAN missile using a different design which allows it to use 100% of its missile's accel.

ThinksMarkedly wrote:That sentence makes no physical sense. The 0.8 or 0.9c limitation of the particle shields applies to top speed, not accel. It doesn't matter how fast you get to that speed, you can't pass it.

It applies indirectly to top speed because of the duration the missile would be able to maintain that accel. Textev frequently includes the enemy's musings "If the missile maintains that accel..."

Plus, I'm positing top speed reached in very short time frames within much shorter engagement ranges of the enemy. Resulting in a missile arriving at .9c from half the normal engagement ranges or less. Equivalent to a sports car's faster 0-60 mph rating.

ThinksMarkedly wrote:Are you proposing an acceleration mode that burns the impeller in less than 60 seconds, but achieves much more acceleration? Say, 200,000 gravities? I remember this part of the thread, and my arguments is that it's not fast enough, unless said missile can achieve ludicrous speeds.

I'm proposing an acceleration that may burn "GA" impellers in less than sixty seconds, but requires much shorter distances to reach the same .9c.

I called it a burst mode. Since the MA will be potentially launching from very short, unprecedented distances then they should be able to guide the missile to it's target without the need to expose it's sensors. Indeed, without the need for the missile to even rely on sensors. Because the LD is so close, it can guide the missile to it's target, thus, also circumventing light speed limitations. Even if traditional missiles are launched from RF ships at maximum range it can pass control to the much closer LD.

ThinksMarkedly wrote:That short range is not less than 1 light-second. Even then it would be dangerously close to an enemy with good sensors or any formation of ships where you couldn't take all of them out in one shot.

At 2 light-seconds away, a missile accelerating at 200,000 gravities would need 12 seconds to strike. At 300k gravities, it's still 10 seconds. To get it under 5 seconds, you need more than 1.2 million gravities, which is 10x more than the the current fastest CM missile known. And it is moving at only 0.2c at the end of this run.

And without sensors? Do you expect the missile to fly in a straight line, like a beam? That makes interception far easier.

And why would the MAN use FTL for this? Note that even the state-of-the-art RMN requires a missile dedicated to being the FTL platform. Even if the MAN can replicate the technology and miniaturise it sufficiently to fit in a missile body, they'd still have to do something like Apollo and send a control missile for every N shipkillers, and all this would achieve is reduce the control loop from 6 seconds to 2.06 (the baseline 2 seconds is the time lag of the sensors). They would need not only an Apollo, but also a Ghost Rider, with sufficient stealth to get much closer than 1 light-second.

Summarising, you're positing that the MAlign achieves:

• An acceleration breakthrough of about 10x
• Sufficiently miniaturised FTL comms to fit a drone and a missile
• Stealth that would allow the drone to close to less than 150,000 km of RMN ships

And all of this still assumes that the LD can generate an intercept course with its targets. I've said this time and again: aside from a fixed location where the ships must go to, that's nearly impossible for ships that are slower than their targets. And for fixed locations, there'll be active radar and ready defences.

The LD would be controlling the missile. I'm also allowing for traditional ships of the RFN launched on GA positions and the LD doubling as a very stealthy GR drone leading the missile to target. Same as GR does.

Also related to that notion is the reality that an LD has to be concerned with occluding stars. Well, the 23E's are sharing snapshots of the battle field, and they're already using insanely capable computers. If they can analyze all of their views of the heavens, the proper algorithm may be able to detect missing stars, in their FOV. (Field of View)

ThinksMarkedly wrote:The sky isn't filled with stars; there's a lot of empty space, or at least where the background object being occluded is sufficiently faint that missiles and ships would not be carrying instruments to detect them.

There might also be an occlusion of other ships. Or an occlusion of another control missile if a net of 23-Es or GR drones are launched to blanket certain areas, as I also proposed in that other thread. Expensive, yes. But warships and people are more expensive.

ThinksMarkedly wrote:

cthia wrote:Somewhere over in the thread, the .8c rad-shield limitation imposed on a missile's accel is the impetus behind my conception of a MAN missile using a different design which allows it to use 100% of its missile's accel.

That sentence makes no physical sense. The 0.8 or 0.9c limitation of the particle shields applies to top speed, not accel. It doesn't matter how fast you get to that speed, you can't pass it.

Plus the 0.8c limit is on rad shielding in ships to protect humans. Missiles already exceed that. Even as far back a Flag in Exile, when talking about ballistic attacks on Grayson's forts / stations (should Honor hold the GSN back under their protection) we got this nugget - "if the Peeps launched at .8 c, their birds' drives would boost them to .99 c before burnout." There was no indication that the missiles couldn't do that, or that their laserheads would be non-function when they reached attack range. (They definitely wouldn't be going for kinetic kills; not with the planet Grayson floating behind most of the targets)

That missile velocity is obviously far easier to reach with a MDM since you don't need anywhere near as much base velocity from the launching ship for the missile to exceed 0.8c. (Heck, in theory an MDM could do so from a standing start; but only in the last several seconds before 3rd stage burnout -- so in practice it's only likely to exceed that if the ship has build up some noticeable velocity before launch)