Relativity

cthia wrote:

Jonathan_S wrote:There's another thing that would make me toss my sliderule. We already discussed the time it takes a huge ship to roll. But it is easy for it to out roll incoming missiles charging in at a significant fraction of light - from various angles launched from several or more ships. Even though they roll ahead of time, many are reaquiring. And again, they are coming in from different angles, having been launched from different ships.

Against missiles coming in a significant fraction of the speed of light the ship has over 6-8 minutes to see which direction they're coming from, and a missile that's spent 5 minutes building up one vector can't exactly turn on a dime to make it through a 90 km or less gap.
So the ship doesn't need to be very handy to deny a clean shot.

If we take an SD the abreast the ship the wedge height varies from 114.75 km to 115.25 km. That gives a total approach angle from which a projectile could see, and theoretically hit, the ship of 75° (+/- 37.5° from the plane of the ship). So a roll of less than 40° completely denies any one missile a flyable path to the target. (And some unknown, but lesser, degree of roll will bring the missile too close to the lip of the SD's wedge and cause it to be vaporized)


Now in theory a missile could diverge even further from the direct path so it is significantly climbing or diving at the enemy such that it would only have a path should the ship roll. But that's unlikely because doing so would shorten the missile's linear range (waste more of its range deviating from and returning to the plane of engagement) and consequently lower its terminal velocity. Or a pair (or more) of missiles could come in on mirrors paths above and below the plane so the ship would have to roll further to deny both a path since rolling away from one would be rolling towards the other. But a 90° roll effectively make the ship invulnerable from missile ramming attacks - they'd have to go so far out of their way to get the necessary approach vector their terminal velocity would be nearly halved and they'd be sitting ducks for point defense.

And all the rolling issue is assuming that it's only the ship's maneuvers that protect it - but the more the missiles try for the unlikely ramming hit the slower their terminal velocity and the longer the defenses have to shoot them down.


Now if a Mk23E or dazzler or dragons tooth missile happens to have a straight on shot at a warship after it's main mission of guiding or covering attack missiles is over then by all means try to ram. But given the unlikelihood of success the most it's likely to accomplish is forcing a bit higher priority of defensive fire directed its way; which might make things a little easier for the next wave of attack missiles. But it wouldn't be worth reducing it's primary mission effectiveness by sticking near the attack missiles by maneuvering early to line up a ramming - the slightly increase on the infinitesimal chance of success isn't worth any measurable decrease in the help it's giving the attack missiles that are vastly more likely to score damage.

Jonathan_S wrote:(OTOH nukes in "burn" mode are hitting the sidewall with a focused plasma burst; which is far more similar to what a relativistic impact would do to a physical object - so I'm not sure what magic keeps a .25c impact - even one likely disintegrated a couple hundred microseconds before - from doing more damage than a, say, gigaton warhead in "burn" mode when the missile should have about 45 times the energy)

Yup, even SDMs should blow a sidewall.

But normally the survivability of sidewalls in the face of high relativistic impacts is theoretically because it's nearly impossible for a missile to pull that off. It's just to easy for the ship to either kill it before it gets that close or roll so it has no angle.

That's what I was figuring--allocating the control missiles to ram is such a threat that they must honor it by rolling--and that reduces the effectiveness of their defenses. If the attacking missile can't ram then the laser clusters can't engage until the missile clears the wedge and lightspeed very well might render that ineffective.

Jonathan_S wrote:Now in theory a missile could diverge even further from the direct path so it is significantly climbing or diving at the enemy such that it would only have a path should the ship roll. But that's unlikely because doing so would shorten the missile's linear range (waste more of its range deviating from and returning to the plane of engagement) and consequently lower its terminal velocity. Or a pair (or more) of missiles could come in on mirrors paths above and below the plane so the ship would have to roll further to deny both a path since rolling away from one would be rolling towards the other. But a 90° roll effectively make the ship invulnerable from missile ramming attacks - they'd have to go so far out of their way to get the necessary approach vector their terminal velocity would be nearly halved and they'd be sitting ducks for point defense.

It's worse than that--the missile would first have to accelerate away then towards the ship.

Now if a Mk23E or dazzler or dragons tooth missile happens to have a straight on shot at a warship after it's main mission of guiding or covering attack missiles is over then by all means try to ram. But given the unlikelihood of success the most it's likely to accomplish is forcing a bit higher priority of defensive fire directed its way; which might make things a little easier for the next wave of attack missiles. But it wouldn't be worth reducing it's primary mission effectiveness by sticking near the attack missiles by maneuvering early to line up a ramming - the slightly increase on the infinitesimal chance of success isn't worth any measurable decrease in the help it's giving the attack missiles that are vastly more likely to score damage.

I would say that even a shipkiller that found itself in ramming configuration should go for it.

The point is not to ram, the point is to ensure the defender hides behind his wedge and degrades his defenses.

Loren Pechtel wrote:The point is not to ram, the point is to ensure the defender hides behind his wedge and degrades his defenses.

The ship has other evasion techniques besides rolling. It can shift its acceleration vector randomly, which makes entry into the wedge nearly impossible. Its position inside the wedge is also impossible to predict from a distance, and can be changed. And can you see through the sidewalls to tell where the ship is, except from very close distances?

No shipkiller would do that. Any shipkiller that is in position to ram is in position to fire directly at the ship. So any shipkiller that would find itself in ramming position would have long before (hands of hands of microseconds) acquired a firing solution and fired, disintegrating itself.

The Mk23E might be able to do that, but do you want a glancing blow to cripple the missile beyond its ability to self destruct, and thus be recoverable by the enemy? Secrecy probably involves the Mk23E and most other missiles to explode to very, very tiny pieces.

Loren Pechtel wrote:
Even vaporized a hit would be deadly.

'It is so written.' The sidewalls and wedge are part of the obligatorily magic you need to accept.

ThinksMarkedly wrote:

Loren Pechtel wrote:The point is not to ram, the point is to ensure the defender hides behind his wedge and degrades his defenses.

The ship has other evasion techniques besides rolling. It can shift its acceleration vector randomly, which makes entry into the wedge nearly impossible. Its position inside the wedge is also impossible to predict from a distance, and can be changed. And can you see through the sidewalls to tell where the ship is, except from very close distances?

No shipkiller would do that. Any shipkiller that is in position to ram is in position to fire directly at the ship. So any shipkiller that would find itself in ramming position would have long before (hands of hands of microseconds) acquired a firing solution and fired, disintegrating itself.

I'm saying that so long as it has a ramming solution it should hold off on detonating. A ram will do far more damage.

The Mk23E might be able to do that, but do you want a glancing blow to cripple the missile beyond its ability to self destruct, and thus be recoverable by the enemy? Secrecy probably involves the Mk23E and most other missiles to explode to very, very tiny pieces.

Even the tiniest of glancing blows will vaporize it.

Loren Pechtel wrote:I'm saying that so long as it has a ramming solution it should hold off on detonating. A ram will do far more damage.

Except that the chance of getting stopped cold by the wedge of a CM goes up exponentially as you get closer to the ship. The whole reason missiles moved from "burn" mode warheads, with a standoff range of 5,000 km, to laserheads, with a standoff range of 30,000 km (later 50,000), was the extra 25,000 km distance drastically improved the percent that survived long enough to detonate.

Going for a ram (even if you have a perfect angle, even if a ram actually will do more damage to a sidewall[1]) instead of detonating as soon as the laserhead is in range is making an extremely low odds (but potentially high payoff) gamble.


[1] Which apparently isn't actually the case for, reasons. (aka authorial fiat)

Loren Pechtel wrote:I'm saying that so long as it has a ramming solution it should hold off on detonating. A ram will do far more damage.

My argument is the same as Jonathan's argument above.

The Mk23E might be able to do that, but do you want a glancing blow to cripple the missile beyond its ability to self destruct, and thus be recoverable by the enemy? Secrecy probably involves the Mk23E and most other missiles to explode to very, very tiny pieces.

Even the tiniest of glancing blows will vaporize it.

On the sidewall, sure. What if it impacts debris coming from the ship or the ship itself? There are several dozen missiles firing in the same 10-millisecond interval, so any one of the others or a combination thereof can bring the sidewalls down. That would make the Apollo missile able to strike directly at the hull... and it could miss.

Anyway, this summarises as the risk vs reward ratio. The risk is too high, the probability of success too low, while the success ratio of other less risky techniques is much higher. There is such a thing as overkill.

Jonathan_S wrote:

Loren Pechtel wrote:I'm saying that so long as it has a ramming solution it should hold off on detonating. A ram will do far more damage.

Except that the chance of getting stopped cold by the wedge of a CM goes up exponentially as you get closer to the ship. The whole reason missiles moved from "burn" mode warheads, with a standoff range of 5,000 km, to laserheads, with a standoff range of 30,000 km (later 50,000), was the extra 25,000 km distance drastically improved the percent that survived long enough to detonate.

In the old days I would agree. Now, though, I don't think the missile will face any defensive fire in that last tenth of a second of flight. Missiles crash through the defense zone fast enough every defensive unit gets only one shot, and since the missiles are arriving as a salvo all the defenses will have already engaged and be reloading/recharging. You can't make every missile ram because then the defenders will hold their lasers until the missiles are closer, but having a reasonable percentage try for it if the geometry permits would be a good idea.

Going for a ram (even if you have a perfect angle, even if a ram actually will do more damage to a sidewall[1]) instead of detonating as soon as the laserhead is in range is making an extremely low odds (but potentially high payoff) gamble.


[1] Which apparently isn't actually the case for, reasons. (aka authorial fiat)

I do agree he got it wrong on missile vs sidewall. I hadn't realized it until this thread, I thought he just hadn't realized the MDM changed the game, but now I realize even the old missiles rammed far harder than a boom setting.

ThinksMarkedly wrote:

Loren Pechtel wrote:Even the tiniest of glancing blows will vaporize it.

On the sidewall, sure. What if it impacts debris coming from the ship or the ship itself? There are several dozen missiles firing in the same 10-millisecond interval, so any one of the others or a combination thereof can bring the sidewalls down. That would make the Apollo missile able to strike directly at the hull... and it could miss.

Anyway, this summarises as the risk vs reward ratio. The risk is too high, the probability of success too low, while the success ratio of other less risky techniques is much higher. There is such a thing as overkill.

A clean miss and it can self destruct. Even tiny debris will vaporize it--it's hitting with antimatter-level energy.