Attacking Darius:

We see a number of squadron/task force/ fleet evasive maneuvers over the course of the series and similarly we see engagement maneuvers. Typically this is when something changes in what is actually going on in a system before (or during or after an initial engagement) and the fleet is maneuvering to either engage the original enemy force or a new one has just appeared OR it is attempting to NOT ENGAGE a force which it doesn't want to fight- usually because the expected outcome is that it will result in damage (usualy a lot of it) to no advantage to yourself. So you change your vector (up to and including reverse and accelerate back along your inbound track to first stop closing the distance to the impending problem and then try to start accelerating away from it.
These are always shown (except for the decelerate and run the other direction) described as curving trajectories where your force intends to run for the hyper limit at best speed and point such that the opponent never gets withing missile range of your ships.

With all the conversation about speed capability (relatively low compared to starships speeds) of a spider drive graser torpedo, the ability to shape a course change to "probably" avoid GTs once you have an indication they are there, should be somewhat better than to try and avoid missile or energy engagement with enemy ship(s). Then there is the question of reorienting your ships to present a wedge forward in the the direction of travel into the possible GTs. You can't see they anyway but neither do we actually have any information of wether or not a GT can reorient its ENERGY Weapon in the time nessisary to engage with a passing shot (over or under etc) at a ship the way a modern missile with a laser head warhead is shown to do. Unless there is a lot I don't understand, you would have an interesting shaped GT with a lot of lensing and gravitational control equipment IN FRONT of the graser emitter for what is essentially an off-bore shot at much closer ranges. The GTs at Manticore are described as slewing around to move their beams though targets (which they have been creeping up to -relative to what the ballistic weapons were making for speed)- which are in known orbits around planets, not hammering along at several hundred g accelerations on top of what their existing speed is.
So, just wondering

kzt wrote:Nope. Everybody starts in energy range. And they shoot first as the RMN is doing the usual RMN 'here we are with our wedges down relaxing...' in the assembly area. Like they did at the Beowulf WH terminus in a recent book.

After all, it's not like the RMN leadership at Beowulf knew they faced a foe who can invisibly position energy weapons within 100,000 km of the most critical and heavily guarded bases of the RMN, right?

Weren't they at low-power wedge, but wedge nonetheless, for station-keeping? We've seen low-power wedge be sufficient for stealth all the way back to SVW at least (I don't think the PNS Sultan had wedge up during First Yeltsin). The question was only of how close one can get before sensors burn through the stealth.

SLN sensors were myopic and at this time the RMN knew exactly how good they were. They knew how far they needed to stay in order to not be observed from the SLN.

Against MAN sensors, those bets were off. A good MAN ship could have seen the RMN ships hiding in low-power wedge. Could it have manoeuvred a weapon asset to strike at them while they were in this condition, taking opportunity to make up-the-kilt or down-the-throat shots? That's basically a Silver Bullet and the RMN should have assumed this could happen. The mitigation would have been the amount of time spent in this state, to avoid the opportunity if someone did observe the ships transiting and bring in assets.

Brigade XO wrote:With all the conversation about speed capability (relatively low compared to starships speeds) of a spider drive graser torpedo, the ability to shape a course change to "probably" avoid GTs once you have an indication they are there, should be somewhat better than to try and avoid missile or energy engagement with enemy ship(s). Then there is the question of reorienting your ships to present a wedge forward in the the direction of travel into the possible GTs. You can't see they anyway but neither do we actually have any information of wether or not a GT can reorient its ENERGY Weapon in the time nessisary to engage with a passing shot (over or under etc) at a ship the way a modern missile with a laser head warhead is shown to do. Unless there is a lot I don't understand, you would have an interesting shaped GT with a lot of lensing and gravitational control equipment IN FRONT of the graser emitter for what is essentially an off-bore shot at much closer ranges. The GTs at Manticore are described as slewing around to move their beams though targets (which they have been creeping up to -relative to what the ballistic weapons were making for speed)- which are in known orbits around planets, not hammering along at several hundred g accelerations on top of what their existing speed is.
So, just wondering

I think we ought to assume the GTs can reorient themselves to fire through the wedge's opening on a turtled ship. All Haven Sector missiles can do that; we don't know if everyone else's missiles can, but MAN missiles probably do. So if they have this capability on missiles, I don't seem them skimping on the torpedoes.

It's more difficult because the torpedo has a larger mass and longer body and therefore a larger moment of inertia resisting that slew. But I don't think it's insurmountable a challenge.

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.

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.

ThinksMarkedly wrote:

Brigade XO wrote:With all the conversation about speed capability (relatively low compared to starships speeds) of a spider drive graser torpedo, the ability to shape a course change to "probably" avoid GTs once you have an indication they are there, should be somewhat better than to try and avoid missile or energy engagement with enemy ship(s). Then there is the question of reorienting your ships to present a wedge forward in the the direction of travel into the possible GTs. You can't see they anyway but neither do we actually have any information of wether or not a GT can reorient its ENERGY Weapon in the time nessisary to engage with a passing shot (over or under etc) at a ship the way a modern missile with a laser head warhead is shown to do. Unless there is a lot I don't understand, you would have an interesting shaped GT with a lot of lensing and gravitational control equipment IN FRONT of the graser emitter for what is essentially an off-bore shot at much closer ranges. The GTs at Manticore are described as slewing around to move their beams though targets (which they have been creeping up to -relative to what the ballistic weapons were making for speed)- which are in known orbits around planets, not hammering along at several hundred g accelerations on top of what their existing speed is.
So, just wondering

I think we ought to assume the GTs can reorient themselves to fire through the wedge's opening on a turtled ship. All Haven Sector missiles can do that; we don't know if everyone else's missiles can, but MAN missiles probably do. So if they have this capability on missiles, I don't seem them skimping on the torpedoes.

It's more difficult because the torpedo has a larger mass and longer body and therefore a larger moment of inertia resisting that slew. But I don't think it's insurmountable a challenge.

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.

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.

That description of how the laser-head works is not correct: the grav-lensing is not ejected, instead it stays with the nuclear charge to change the radiation blast from omnidirectional to focused on the laser rods. It is the laser rods that are ejected forward of the missile and they can be rotated to point in the direction of the target. There have been pictures published in the books, but I cannot find one.

As to whether the graser is fixed in the torpedo body (so the entire body has to rotate or it is in a flexible mounting that can point independent of the torpedo body; I do not think we know specifically. However the independent mount would likely be better, in my opinion.

tlb wrote:That description of how the laser-head works is not correct: the grav-lensing is not ejected, instead it stays with the nuclear charge to change the radiation blast from omnidirectional to focused on the laser rods. It is the laser rods that are ejected forward of the missile and they can be rotated to point in the direction of the target. There have been pictures published in the books, but I cannot find one.

As to whether the graser is fixed in the torpedo body (so the entire body has to rotate or it is in a flexible mounting that can point independent of the torpedo body; I do not think we know specifically. However the independent mount would likely be better, in my opinion.

Thanks for the correction. I had the wrong terms, but the idea remains that there are independent focusing elements that can orient on the target or targets.

I think there's some information on the graserheads in TEiF which are relevant here.

tlb wrote:As to whether the graser is fixed in the torpedo body (so the entire body has to rotate or it is in a flexible mounting that can point independent of the torpedo body; I do not think we know specifically. However the independent mount would likely be better, in my opinion.

Except it's described as a CL's graser. That's going to be more probably over 8 meters long (too lazy to go try to find a more exact reference) so it seems unlikely to me that you'd be able to put it on any kind of flex mounting. (Though the grav lens can probably adjust the beam pointing by at least a few degrees off of dead ahead)

I suspect if a GT is going to make a snap shot as it overflies a target it's going to need to stop acceleration a little while before and pivot its entire body so it coasts past the target with its nose already pointed at the target's most probable location. That way it can start firing the moment it clears the wedge's edge; and try to correct onto target as it goes. (Though depending on its closing speed it may get only fractions of a second to react, so it might have no more chance to correct for a bad guess than a laser-head would. At high relativistic closing speeds it could clear one wedge, and then be blocked by the other in less time that it takes to see the target and react)

Jonathan_S wrote:I suspect if a GT is going to make a snap shot as it overflies a target it's going to need to stop acceleration a little while before and pivot its entire body so it coasts past the target with its nose already pointed at the target's most probable location. That way it can start firing the moment it clears the wedge's edge; and try to correct onto target as it goes. (Though depending on its closing speed it may get only fractions of a second to react, so it might have no more chance to correct for a bad guess than a laser-head would. At high relativistic closing speeds it could clear one wedge, and then be blocked by the other in less time that it takes to see the target and react)

That's something we can calculate.

Perls of Weber: Wedge Geometry lists for an SD:

• throat: 190 km
• kilt: 40 km
• width: 300 km

If the ship is dead centre in the wedge and the torpedo passes it exactly atop and perpendicular to the wedge, we'll get average values. That is to say: the ship will not be dead centre and the torpedoes will not pass exactly perpendicular, but since the throat is wider than the after aspect, we can calculate what missiles will see, on average, passing by an arbitrary SD.

From the centre of the wedge, the distance from floor to ceiling is (190 + 300) / 2 = 245 km. That means from the ship, the floor or ceiling is 122.5 km away in the altitude direction and the edge of that wedge is another 150 km away in the lateral direction. We don't need to calculate the angle (it's simple trigonometry, though). We can just use triangle similarity.

If the torpedo is passing at 30,000 km away, it's at 200x the distance from the ship as the edge of the wedge is from the ship. That means it a clear shot for a transversal distance of 200 x 245 = 49,000 km. If that missile is moving at a third the speed of light, it's going to have a clear shot for 0.49 seconds. From this, you need to subtract 0.1 seconds light-speed lag for the reaction of the missile once it has cleared the wedge, seen the ship and reoriented. Minus a bit more because the reaction isn't instantaneous.

At the same speed, if it wants to have a shot for 3 seconds, it needs to be 6x further away, so 180,000 km, but that also increases the time-lag reaction to 0.6 seconds, making the shot on target last for 2.4 seconds.

Or, at the same distance, it would need to be moving at one sixth the speed, or a mere 12,500 km/s, to be able to have 3 seconds of opening and only 0.1 second time-lag.

It's simple math to calculate where it needs to be and what speed so it has a full 3 seconds firing time including the time lag to orient itself. Exercise is left for the reader.

But either scenario presents its own problem. On one, the torpedo is far enough away that its energy is attenuated considerably. At 200,000 km, can a graser penetrate an SD sidewall? Plus, the ship will be jinking all the way, so the 0.6 second time-lag is significant to react to the evasions. It's unlikely to be able to maintain the full 3 seconds on target. In fact, it'll be challenged to even hit the ship: this is why multiple lasing rods have an advantage, since they can bracket all the possible locations the ship can be in the time it'll take for the laser to arrive and ensure that at least some beams strike.

On the other scenario, the torpedo is moving very slowly compared to the ship and it's extremely close. More than that, it's already been within 50,000 km from its target for about 0.8 seconds before it cleared the wedge and was able to engage. A Keyhole II-equipped ship will likely be firing at it before it can engage. The ship can patiently wait for the missile to get closer because it can't fire until it's cleared the wedge, so it can spend those 0.8 seconds refining the target and burning through its stealth.

As for the rate of rotation, if my trigonometry didn't fail me, it's 0.45 rad/s ≅ 26 deg/s ≅ 4.3 rpm.

ThinksMarkedly wrote:On the other scenario, the torpedo is moving very slowly compared to the ship and it's extremely close. More than that, it's already been within 50,000 km from its target for about 0.8 seconds before it cleared the wedge and was able to engage. A Keyhole II-equipped ship will likely be firing at it before it can engage. The ship can patiently wait for the missile to get closer because it can't fire until it's cleared the wedge, so it can spend those 0.8 seconds refining the target and burning through its stealth.

Since at Darius (unlike possible spoiler situations) the graser torpedoes will have spider drives; it is not yet clear that targeted ships will have any idea about "refining the target and burning through its stealth". At the moment, the only way we expect the Darius torpedoes to be spotted is by active targeting radar, with the resulting limitations.

tlb wrote:Since at Darius (unlike possible spoiler situations) the graser torpedoes will have spider drives; it is not yet clear that targeted ships will have any idea about "refining the target and burning through its stealth". At the moment, the only way we expect the Darius torpedoes to be spotted is by active targeting radar, with the resulting limitations.

The problem is that they have to be very far or very slow in order to fire that graser for the full three seconds. In one case, its effectiveness is diminished; in the other, its stealth is compromised before it reaches the target. The point-defence in an enemy-held system will be free to act on its own in case it detects a threat, and 0.8 seconds is an eternity.

They could instead operate like a regular missile and fire for less than a tenth of a second, allowing for a 30x times closer and/or faster approach. But that nullifies the biggest gain of the graserhead. It would be best to actually implement something like the Hasta that fires a swarm of regular missiles with millisecond graserheads once it gets close enough.

ThinksMarkedly wrote:The problem is that they have to be very far or very slow in order to fire that graser for the full three seconds. In one case, its effectiveness is diminished; in the other, its stealth is compromised before it reaches the target. The point-defence in an enemy-held system will be free to act on its own in case it detects a threat, and 0.8 seconds is an eternity.

They could instead operate like a regular missile and fire for less than a tenth of a second, allowing for a 30x times closer and/or faster approach. But that nullifies the biggest gain of the graserhead. It would be best to actually implement something like the Hasta that fires a swarm of regular missiles with millisecond graserheads once it gets close enough.

Not really. Typical velocity will be under 30,000 KM/sec, so you can open fire at 90,000 KM and fire for three seconds, then two clouds of plasma pass through each other. Range at which you can burn-through a sidewall is highly unclear due to lack of data.

If you can arrange to engage against the front or rear that would be best. You can also engage against the rear where the range is continually opening as opposed to closing.