Relativity

Jonathan_S wrote:

cthia wrote:It is impossible to change the attitude of a missile traveling over 93% of light speed enough for something to be targetable. Especially when that something is more maneuverable.

I'd agree if you'd said the vector of the missile.
But the attitude is just the direction it's pointing. It's no harder to change the attitude of a missile moving at .93c that it is to change one at rest.

Well, at least in the missiles reference frame. Time dealation would make it look somewhat more sluggish to an outside observer.
Still, if the target ship would see a missile at rest take, say, 5 seconds to rotate 90 degrees then I think it'd see it take about 7 seconds to make that same rotation at .93c.


The difference is that the higher your base velocity the less deflection you achieve for the same amount of lateral acceleration. The acceleration produces the same lateral velocity and so the same lateral deflection over any given interval. But that gives a far different "slope" when the base velocity is so much higher.

Agreed. I meant to change that to reflect the sentiment in my original post upstream. This post grew way too long, and the follow up was lost while editing. Editing snafus caused by my editor being jealous of my present company.

It would be impossible to change vectors. And every case of reacquiring would only be possible if a ship flew right in its wake. A point that also got left out of the replacement post.

The bit about the attitude which was left out while editing had to do with engagement times afforded by a missile traveling over 93 % of light being able to target a maneuvering ship with an optimum blast of its beams. Lacs only get one shot?

You may disagree, but those pills are going in my medicine cabinet.

Other notions which were lost in that post is a mention about the lensing system - which might simply be a result of my misunderstanding. It has to be an internal structure of the missile which is spinning to orient itself for an optimum shot. The missile itself can't spin, or it wouldn't be able to stop on a dime. An internal structure can stop against the missile body. But then, the missile is already spinning. To be honest, without Apollo (and even then) I don't know how the Peeps or the RMN ever hit the broad side of a barn.

At any rate, this spinning and targeting has to be accomplished during the short engagement times. Granted, missile standoff range compensates some for accuracy. But we're talking about targeting, correcting attitude, altering vectors, and readjusting attitude within the engagement window of a .93c flyby. BTW, crossing the T? Slipsticks - the notorious slide rules - have no place within a parsec of a sc-fi novel.

cthia wrote:Other notions which were lost in that post is a mention about the lensing system - which might simply be a result of my misunderstanding. It has to be an internal structure of the missile which is spinning to orient itself for an optimum shot. The missile itself can't spin, or it wouldn't be able to stop on a dime. An internal structure can stop against the missile body. But then, the missile is already spinning. To be honest, without Apollo (and even then) I don't know how the Peeps or the RMN ever hit the broad side of a barn.

At any rate, this spinning and targeting has to be accomplished during the short engagement times. Granted, missile standoff range compensates some for accuracy. But we're talking about targeting, correcting attitude, altering vectors, and readjusting attitude within the engagement window of a .93c flyby. BTW, crossing the T? Slipsticks - the notorious slide rules - have no place within a parsec of a sc-fi novel.

Why does the missile have to stop on a dime?. At the engagement point the missile throws the laser rods out and they adjust to point at the target, then the warhead explodes to pump the lasers. This can be done while spinning.

cthia wrote:Other notions which were lost in that post is a mention about the lensing system - which might simply be a result of my misunderstanding. It has to be an internal structure of the missile which is spinning to orient itself for an optimum shot. The missile itself can't spin, or it wouldn't be able to stop on a dime. An internal structure can stop against the missile body. But then, the missile is already spinning. To be honest, without Apollo (and even then) I don't know how the Peeps or the RMN ever hit the broad side of a barn.

At any rate, this spinning and targeting has to be accomplished during the short engagement times. Granted, missile standoff range compensates some for accuracy. But we're talking about targeting, correcting attitude, altering vectors, and readjusting attitude within the engagement window of a .93c flyby. BTW, crossing the T? Slipsticks - the notorious slide rules - have no place within a parsec of a sc-fi novel.

I don't think the missile itself is spinning as it flies; nor do I think it spins itself to point its nose at the target. The lasing rods appear to be free flying sub-munitions that move from their stowage position out to the needed spot for firing; and the grav plate the missile forms to better focus the blast towards them presumably doesn't need its emitters rotated around to place the warhead physically between them and the lasing rods.


If the missile's target is rolled behind it's wedge then the missile is basically going to have to take a blind snapshot as it clears the wedge and hope the shotgun effect of the multiple lasing rods lets it score a lucky hit. Basically aim at center of the intrawedge volume and hope the ship isn't far from there, because the missile's not going to have time in the ~0.0006 seconds were it can see the target as it flashes past the broadside opening of the wedge to adjust it's aim.

But if the target isn't rolled then the missile has something of a view of it through the sidewall (or a better view through the throat or kilt of a target in a chase scenario) before it enters attack range - and so it doesn't have to guess as much about where to aim its several lasing rods.

But whether it's got a view of the target, or making a snap blind-fire shot, I'd assume that several seconds before reaching attack range the missile would strike its wedge, kick the lasing rod assemblies out to align themselves towards the target spot, and bring up the grav plate ready to focus the blast into the lasing rods. So everything should be pointed exactly at the spots the missile wants to hit just before it reached the attack point and detonates.

Jonathan_S wrote:I don't think the missile itself is spinning as it flies; nor do I think it spins itself to point its nose at the target.

Whether or not spinning is a normal behavior of a missile, we know that it can do it based on the short story The Service of the Sword.

tlb wrote:

Jonathan_S wrote:I don't think the missile itself is spinning as it flies; nor do I think it spins itself to point its nose at the target.

Whether or not spinning is a normal behavior of a missile, we know that it can do it based on the short story The Service of the Sword.

A spinning missile could probably avoid counter-missiles easier. Instead of a predictable cone of movement when maneuvering you can have a cone that's corkscrewing since the wedge is also spinning with the missile, and the wedge geometry determines how you can maneuver.

tlb wrote:

Jonathan_S wrote:I don't think the missile itself is spinning as it flies; nor do I think it spins itself to point its nose at the target.

Whether or not spinning is a normal behavior of a missile, we know that it can do it based on the short story The Service of the Sword.

Can I suggest we find a more descriptive term than "spinning?"

I think some others were, like me, thinking this meant "rotating along the longitudinal axis" like a bullet does, probably because we were thinking of "spinning like a top." This is useless for targetting, since it doesn't change the direction of the warhead. It could help with defence, because the wedge is also rotating and thus covering the sides, but that's only useful against PDLCs, so in a very terminal phase of engagement.

Rotating along the two other axes (yawing and pitching) are probably what the missile does when targetting the enemy ship. If the wedge is still active at this time, then either rotation will also change the acceleration vector.

tlb wrote:

Jonathan_S wrote:I don't think the missile itself is spinning as it flies; nor do I think it spins itself to point its nose at the target.

Whether or not spinning is a normal behavior of a missile, we know that it can do it based on the short story The Service of the Sword.

Well... technically... that story was about a drone, not a missile.
But yes, the drone in SofS was able to spin - presumably to simulate a notional light warship like a DD or CL trying to make snap energy shots between interposing its wedge; rather than trying to simulate a notional missile.


Still, I've no reason to doubt that a missile could spin like a top around its longitudinal axis should it ever want to. Mind you, doing so at any significant RPM would probably lead to degradation of what its sensors could see - since they cover a fair bit of the nose and so different parts would be moving at different linear velocities in such a spin. (And it also approaches its target from nose on - so rotating the wedge like that doesn't provide any protection from defensive energy fire as that's coming 'down the throat' at it)

ThinksMarkedly wrote:

Loren Pechtel wrote:A hit with a piece of antimatter won't vaporize it?!?! Because the debris might as well be antimatter for the damage it will do.

Where would the antimatter come from? This is not Starfire, there are no AMBAMMs in the Honorverse. I'm sure they have the technology for it, but it is probably still expensive enough to make antimatter that it's not economically viable. Energy is cheap and plentiful via fusion and hyperspace.

The missile has kinetic energy similar to it's rest mass. That makes collisions the equivalent of low-speed collisions with antimatter, except all the boom is directed inwards.

Of course. The shipkillers would deploy normally. It's just if they have clear sailing the might decide to ram. I've already pointed out that it's very unlikely they will face any defensive fire as they close.

I disagree with that. The defence systems will prioritise any missiles that are close enough and have a free shot, which is required for ramming. A missile that fails to shoot at 24,000 km but instead continues to approach at 0.8c would still need 0.3 seconds before it could ram. That's a lot of time. A PDLC cluster with 16 lasers can fire each one every 2 seconds, which means it fires every 0.125s. So in the time it takes the missile to close the distance for ramming, the PDLC can fire twice. And there are multiple PDLCs.

But these days it doesn't fire every .125s, all of those 16 shots will have been expended before the missiles reached standoff range, there will be none left if a missile doesn't fire at standoff range. Figuring one shot per .125s made sense in the old days where the lasers got multiple shots at each missile, it doesn't apply to MDMs.

More importantly, the missiile can miss an opportunity that won't come again. If it has a clear shot at the hull, it has to take it. It won't know whata jinks the ship will take in the next two or three hundred milliseconds. If the flight line was already not perfect, like coming close to the edge of the wedge, it can become impossible if the ship executes an evasive manoeuvre. The missiles more likely to be able to execute the ramming are also those that have the best shot for their payload.

Why would they waste the opportunity?

It could still fire if the solution starts to degrade. However, it's got a booster far superior to the ship, it can match any maneuver other than rolling.

Of course it can't--but it doesn't need to. It's got the feed from those other missiles, it knows where the target is.

Up until the moment that the shipkillers fire and stop existing. From that point on, the ACM is on its own. Since it's behind the others, the position of the ship becomes uncertain, though I'll grant you it's minimal (the ACM is probably in the order of 200 km away, which means only 0.83 ms).

Once the shipkillers fire they are no longer blocking the view.