Attacking Darius:

tlb wrote:What you are missing is that during the time that "those signals took" "to get to the torpedo" the ship can move; what the torpedo sees is not the present image of the ship, but a view of it from the lapsed time ago. So overall the effect is that aiming has to allow for movements based on the round-trip time, not the one-way time. That mistake may be why you discount that the missiles primary sensors are looking at the wedge, with only secondary sensors that might be looking at the light speed image of the target.

ThinksMarkedly wrote:Not exactly. The torpedo always sees where the ship was a single-way-time ago. From the point of view of the ship, the torpedo reacts to its evasions at round-trip-time.

The primary sensors can indeed see the wedge in FTL, but the torpedo has seen that wedge for the past half hour already. But that doesn't tell the torpedo where precisely the ship is within the volume it determined the wedge to be. Assuming the torpedo can generate an intercept with that wedge, it still needs to clear the wedge in order to see the ship.

To traditional missiles, GA ships would indeed have rolled their wedges, presenting the worst scenario from the missile's point of view: perpendicular to their base velocity vector. This is where my calculations are correct: once the sensor clears the wedge, it can pinpoint where the ship was single-way-time ago. The ship will continue to move, which is why said warhead must either have multiple beams to bracket all positions or it must be close enough that it can swing the beam to a position the ship must occupy within that time.

For a torpedo, we have to assume the ship will not have seen the torpedo coming until far too late. I maintain that the shell of Ghost Riders will see something, but by the time the torpedo is within 15 seconds from target. They'd need to see the threat earlier to interpose the wedge completely.

The calculation I made assumed the worst case scenario for the torpedo, which is unlikely. It calculated the minimum distance or maximum velocity the torpedo could be at so it can fire full 3 seconds at where it has seen the ship or predicted it will be, in that perpendicular case.

There is no reason, of which we are currently aware, to think that Ghost Rider will see the spider drive torpedo before it shoots. But that is an argument for another day and maybe by then you will be correct.

You seem to say that you know that light travels from the ship to the missile in an amount of time (so the missile sees that ship as it was that time ago) and you seem to say that you know the graser beam will take about the same time to travel from the missile back to the calculated position of the ship. So I do not understand why you say "not exactly", when I say that very thing.

In the Honorverse, I am not sure that there actually is this optical step that you want to add. A missile of any type reads the wedge to know its position and orientation and tries to fire through the openings in the front or back (failing to get such a shot, it will target the sidewall). The laser head missile has multiple aimed rods to maximize its chances of hitting something within the space defined by the wedge. The graser headed torpedo will have to use vibration and rotation to swing the beam through the enclosed space to achieve the same thing. Since we agree that the position of the ship within the wedges is not well known (without your optical step); that means this process might get that "magic BB" hit, but it is much more likely that large number of missiles targeting one ship is needed to cause significant damage. Why do I believe this? Because this matches how every missile fight that we have seen has played out.

tlb wrote:

tlb wrote:What you are missing is that during the time that "those signals took" "to get to the torpedo" the ship can move; what the torpedo sees is not the present image of the ship, but a view of it from the lapsed time ago. So overall the effect is that aiming has to allow for movements based on the round-trip time, not the one-way time. That mistake may be why you discount that the missiles primary sensors are looking at the wedge, with only secondary sensors that might be looking at the light speed image of the target.

ThinksMarkedly wrote:Not exactly. The torpedo always sees where the ship was a single-way-time ago. From the point of view of the ship, the torpedo reacts to its evasions at round-trip-time.

The primary sensors can indeed see the wedge in FTL, but the torpedo has seen that wedge for the past half hour already. But that doesn't tell the torpedo where precisely the ship is within the volume it determined the wedge to be. Assuming the torpedo can generate an intercept with that wedge, it still needs to clear the wedge in order to see the ship.

To traditional missiles, GA ships would indeed have rolled their wedges, presenting the worst scenario from the missile's point of view: perpendicular to their base velocity vector. This is where my calculations are correct: once the sensor clears the wedge, it can pinpoint where the ship was single-way-time ago. The ship will continue to move, which is why said warhead must either have multiple beams to bracket all positions or it must be close enough that it can swing the beam to a position the ship must occupy within that time.

For a torpedo, we have to assume the ship will not have seen the torpedo coming until far too late. I maintain that the shell of Ghost Riders will see something, but by the time the torpedo is within 15 seconds from target. They'd need to see the threat earlier to interpose the wedge completely.

The calculation I made assumed the worst case scenario for the torpedo, which is unlikely. It calculated the minimum distance or maximum velocity the torpedo could be at so it can fire full 3 seconds at where it has seen the ship or predicted it will be, in that perpendicular case.

There is no reason, of which we are currently aware, to think that Ghost Rider will see the spider drive torpedo before it shoots. But that is an argument for another day and maybe by then you will be correct.

You seem to say that you know that light travels from the ship to the missile in an amount of time (so the missile sees that ship as it was that time ago) and you seem to say that you know the graser beam will take about the same time to travel from the missile back to the calculated position of the ship. So I do not understand why you say "not exactly", when I say that very thing.

In the Honorverse, I am not sure that there actually is this optical step that you want to add. A missile of any type reads the wedge to know its position and orientation and tries to fire through the openings in the front or back (failing to get such a shot, it will target the sidewall). The laser head missile has multiple aimed rods to maximize its chances of hitting something within the space defined by the wedge. The graser headed torpedo will have to use vibration and rotation to swing the beam through the enclosed space to achieve the same thing. Since we agree that the position of the ship within the wedges is not well known (without your optical step); that means this process might get that "magic BB" hit, but it is much more likely that large number of missiles targeting one ship is needed to cause significant damage. Why do I believe this? Because this matches how every missile fight that we have seen has played out.

As I posited a few salmon strokes upstream, a 3-second-firing graser represents a lot of missiles, if it can get the lion's share of that hellfire on target.

cthia wrote:As I posited a few salmon strokes upstream, a 3-second-firing graser represents a lot of missiles, if it can get the lion's share of that hellfire on target.

I think the current disagreement is over what precisely is meant by "on target". I am positing that missiles may well be firing (whether laser or graser head) at the point when the missiles computes that the beams will go through the openings; even though it can not yet see (by light speed sensors, if any) into that opening. That is simply a result of the distances and/or speeds involved.

Then if computes that the opening will not be available, it targets the sidewalls instead; trying to open a way for the follow up missiles.

Theemile wrote:Side walls also block precise line of site to the ship generating them - So a ship with sidewalls and bucklers should keep a torp from getting a good location of the actual ship's position relative to the wedge - however it should be able to get a decent reading on the location of the wedge itself.

Though bucklers seem to cover only a very small range of angles, all quite close to dead ahead or dead astern. It presumably has the same 10 km standoff distance as normal sidewalls; and we're told that it's less than twice the diameter of the ship's maximum beam. So for an SD that'd put it at less than 404 m across (and less than 101 meters wider than the ship's maximum beam at its hammerheads). 404 m at 10 km means a bow buckler is only protecting the entire ship from observation (or fire) coming from within ±0.51° of directly ahead - (The bow, being closer to it, is protected up to about ±0.58° off angle)

Now if they accepted less standoff protection and cut the distance in half (5km) they'd get better coverage; up to ±0.91°

And if they cut it in by 3/4 (2.5 km) they'd be up to ±1.5°.

But any of those closer locations means it's less effective at bending away, or dispersing, incoming fire that does hit the buckler than a conventional sidewall of the same strength -- so it's a definite trade-off between coverage and damage reduction.


For contrast the vulnerable angle down the 'trench' formed by projecting the sidewalls the length of the wedge is ±1.9°, and vertically the angle between the wedges is ±17.5° fore or ±3.8° aft.



So a graser torp that manages to get a mostly ahead, or astern, position actually seems quite unlikely to have its view impeded by the buckler as it's covering only a small minority of the angles open fore/aft between the sidewalls and the wedge (especially in the vertical).

Note: Those angles are somewhat approximate. On the one hand we don't know how much less that twice the maximum beam the buckler covers; so I just used 2x the max beam. On the other hand I didn't adjust for the widest points being in somewhat from the hull ends, so I just calculated the triangle as if the aft hammerhead's widest spot was at the absolute stern. However they at least give the ballpark of the narrowness of angle being covered

Loren Pechtel wrote:

ThinksMarkedly wrote:Or maybe not. Maybe the regular missiles themselves aren't reorienting, only the warheads are. We know that during attack, the missile ejects the grav lensing before the body detonates to produce the energy that will be channelled into the X-Ray laser. We know the GA has independently-focusing lenses, multiple ones in each missile. So maybe the missile itself isn't reorienting, only those lenses do.

That's how I see it, also. The rods and associated equipment are ejected before detonation, the missile is ballistic at that point and there's no reason the rods can't turn to point at whatever they want. The missile never points.

In which case a 3-second graser may not be able to do it.

I don't think this will be relevant in the story, even if so.

If it can't point it's useless.

Any missile that is fired as part of a salvo has to be able to somehow aim its beam. Otherwise they would simply destroy each other. As for g-torps, I imagine it would be as fatal as wedge fratricide. Beam fratricide?

.

ThinksMarkedly wrote:

Loren Pechtel wrote:
And those signals took time to get to the torpedo.

ThinksMarkedly wrote:Not really. We're not talking about radar or lidar, meaning it's a round-trip for the signal. Passive sensors can see the photons that were already on the way from the ship and simply got intercepted by the torpedo.

Yes, they did. But the point is that they were underway to the position the torpedo will be before the torpedo got there. So the time it took them is irrelevant to the calculation. But it does match the time the gamma-ray photons the torpedo will fire will take to get back.

Hence, single-way light lag, not round-trip.

No. Lets say it's 300,000km out for convenience.

At t=0 the missile clears the wedge and can see the ship. However, it sees where the ship was at t=-1 and it's beam hits at t=+1. Thus the ship has two seconds of evasion and at Honorverse accelerations that's enough to make the hit probability pretty small.

Loren Pechtel wrote:At t=0 the missile clears the wedge and can see the ship. However, it sees where the ship was at t=-1 and it's beam hits at t=+1. Thus the ship has two seconds of evasion and at Honorverse accelerations that's enough to make the hit probability pretty small.

That's exactly correct. The point is that at t=0 the warhead can see the ship. Until that point, it couldn't, so it couldn't know where to fire to strike the ship. It's indeed where the ship was at t=-1, but that's enough information to discard all other possible positions where the ship hadn't been seen at t=0. It's also sufficient to estimate where the ship can be at t=+1, so it can aim the multiple beams.

That's all I've been trying to say.

However, minding what tlb said:

tlb wrote:I think the current disagreement is over what precisely is meant by "on target". I am positing that missiles may well be firing (whether laser or graser head) at the point when the missiles computes that the beams will go through the openings; even though it can not yet see (by light speed sensors, if any) into that opening. That is simply a result of the distances and/or speeds involved.

A missile with millisecond-range beams may not be firing at the sidewall, but a 3-second graserhead might. The moment it has an opening onto the sidewall and has a reasonable certainty that it'll swing over a direct line-of-sight to the actual target, it should begin firing.

I'd need to do the math, but I suspect that even in the worst case (perpendicular wedge), the warhead could begin firing at twice the distance. That means it could come in twice as fast or twice as close.

tlb wrote:There is no reason, of which we are currently aware, to think that Ghost Rider will see the spider drive torpedo before it shoots. But that is an argument for another day and maybe by then you will be correct.

We will indeed discuss what you're thinking of another day, but I was making a reference to a calculation I made earlier in this very thread, before TEiF came out and gave us some more data to make speculations on.

We're told that the MAN suspects its stealth is good up to 1 light-second. I'm saying it's pretty easy to create a shell of Ghost Riders no more than 1 light-second from each other and 1 or 2 million km from the nucleus of the Grand Fleet, so that nothing slips by them undetected, regardless of angle of interception. As White Haven put it, "saturate with Ghost Riders so we can walk over them."

No stealth is perfect. Burning through it is a matter of energy: either more energy or a shorter distance will, eventually, get the job done. What the GA doesn't know is how much of it is needed or if there are any weaknesses in the torpedo frames or the spider drives that can allow detection in a simpler way. So they will back some back-of-the-envelope calculations, based on assumptions for a worst-case scenario until data comes in.

Unfortunately for the subject of this thread, if the objective is to attack Darius, then there won't have been any data before the attack launches. On the other hand, if the MAlign is using their torpedoes in actions across the Galaxy, they'll be giving data to the GA.

In the Honorverse, I am not sure that there actually is this optical step that you want to add. A missile of any type reads the wedge to know its position and orientation and tries to fire through the openings in the front or back (failing to get such a shot, it will target the sidewall). The laser head missile has multiple aimed rods to maximize its chances of hitting something within the space defined by the wedge. The graser headed torpedo will have to use vibration and rotation to swing the beam through the enclosed space to achieve the same thing. Since we agree that the position of the ship within the wedges is not well known (without your optical step); that means this process might get that "magic BB" hit, but it is much more likely that large number of missiles targeting one ship is needed to cause significant damage. Why do I believe this? Because this matches how every missile fight that we have seen has played out.

A missile wants to hit the ship, not the sidewall. So if it is coming to the wedge in such a geometry that the sidewall is partially obscured and the ship is not visible at all, will it fire?

A regular laserhead missile has one shot. If it fires on the sidewall, it will not fire on the ship, even if its trajectory later takes it to a position where it can see where the ship is (or was, light-time lag). A missile is never flying alone, not since Travis' time anyway, so firing on the sidewall is probably a gain, so long as at least one missile fires on the ship. Are the missiles networked so that they take a vote (read: run an algorithm) and elect some of their members to hold fire until they can precisely pinpoint the ship?

Or, instead, will they do what you seemed to suggest: that they all fire at the most likely locations where the ship can be and hope that at least one of them can score a hit?

On the other hand, a 3-second graserhead is quite different. As I said above, reacting to your later post, it could begin firing before it can precisely pinpoint the ship and still swing its aiming rods to where the ship is or within a volume of that.

Theemile wrote:Of course this is the same as localizing New Jersey from the Moon. (or worse)

More like, having localised New Jersey while standing on the Moon, you want to hit the Newark Airport. Because that'll be a gain for everyone: no one wants to go to EWR (they just have to). If you're like me, you've heard of the airport or even transited through it, but I've never looked at a map of New Jersey and couldn't say where in that the airport is.

That's not a bad analogy. The size of New Jersey is probably comparable to the opening of the wedge; while the airport is probably 5x as big as the ship in linear dimensions (so 25x as big in area), the starting position on the Moon is probably 10x as far too.

ThinksMarkedly wrote:

Theemile wrote:Of course this is the same as localizing New Jersey from the Moon. (or worse)

More like, having localised New Jersey while standing on the Moon, you want to hit the Newark Airport. Because that'll be a gain for everyone: no one wants to go to EWR (they just have to). If you're like me, you've heard of the airport or even transited through it, but I've never looked at a map of New Jersey and couldn't say where in that the airport is.

That's not a bad analogy. The size of New Jersey is probably comparable to the opening of the wedge; while the airport is probably 5x as big as the ship in linear dimensions (so 25x as big in area), the starting position on the Moon is probably 10x as far too.

Actually, to take it further, the Airport is probably the region a ship "could be in" relative to the wedge, where as the actual location of the ship is one of the terminals.