Honorverse ramblings and musings

Jonathan_S wrote:

cthia wrote:From the location of the missile launchers, courtesy of MaxxQ, that doesn't seem plausible. The much larger Honorverse missiles have to clear the much larger external dimensions of Honorverse ships before reversing direction -- at least in consideration of reversing direction.

Also, my post was a bit unclear err inaccurate. There is a difference in net acceleration per unit time of the two broadsides. The off-bore launch has a negative acceleration of one vector component, which is momentarily, quite possibly, opposite the target.

In that worst case, 180° off bore, as Weird Harold said the facing launchers would most likely use delayed start to synchronize the salvos.

The worst case missile that might be used for this backwards firing attack would be a single drive extended range missile (ERM/LERM). The common ones of those have a 75/225 second burn (though I think the RMN's is better, but we'll got with the 225 at half power for the calculation).

1 second of burn away gets the missile out to 230 km away from the enemy, more than enough to clear the wedge. Another 0.75 seconds burning vertically will add 129 km of elevation, coming above (or below) the wedge. By this point the missile has moved 575 km away from the enemy. It'll take 2.871 seconds accelerating back towards the target to make up that distance.

But call it a total of 6 seconds lost, to allow for turning times and killing the vertical vector. The missile will have a net velocity of 861 kps towards the enemy when it passes the launching ship, and the remaining 219 seconds on its drive will let it reach 11,219,515 km, with 101,601 kps terminal velocity.

That little U-turn cost it 3.6% of its range and 1.8% of its terminal velocity. [11,219,515 km @ 101,601 kps vs 11,643,750 km @ 103,500 kps]. The missiles launched directly towards the enemy would need to delay spinning up their drives about 4.2 seconds in order to synchronize the 2 halves of the salvo.


The longer the missile's powered endurance the lower, proportional, the impact of 6 second U-turn would be. However even in this worst case scenario it seems well worth paying a few percent reduction in range to double the size of a salvo. (And, if you wanted less impact, you could point your nose or tail at the target so both broadsides need just a 90° turn)

I believe we've been told that EDMs (with 2nd gen offbore tech) can only be f1red ~135 degrees offbore. This is sufficient to cover the adjacent firing arcs, but not the opposite arcs. MDMs and DDM, with 3rd gen offbore, can fire 180 degrees offbore so can cover the opposite firing arc.

I think the capability is all in the engine burn times, with EDMs having the extra power to overcome their initial vector and reorient onto target, and MDMs having power to spare.

Theemile wrote:I believe we've been told that EDMs (with 2nd gen offbore tech) can only be f1red ~135 degrees offbore. This is sufficient to cover the adjacent firing arcs, but not the opposite arcs. MDMs and DDM, with 3rd gen offbore, can fire 180 degrees offbore so can cover the opposite firing arc.

I think the capability is all in the engine burn times, with EDMs having the extra power to overcome their initial vector and reorient onto target, and MDMs having power to spare.

Now that you say that it does ring a bell. Ah well, even as a theoretical demonstration it shows that starting off going the wrong way shouldn't be a major impact on ERM/DDM/MDM missile range or performance.

Jonathan_S wrote:

Theemile wrote:I believe we've been told that EDMs (with 2nd gen offbore tech) can only be f1red ~135 degrees offbore. This is sufficient to cover the adjacent firing arcs, but not the opposite arcs. MDMs and DDM, with 3rd gen offbore, can fire 180 degrees offbore so can cover the opposite firing arc.

I think the capability is all in the engine burn times, with EDMs having the extra power to overcome their initial vector and reorient onto target, and MDMs having power to spare.

Now that you say that it does ring a bell. Ah well, even as a theoretical demonstration it shows that starting off going the wrong way shouldn't be a major impact on ERM/DDM/MDM missile range or performance.

I would suspect that offbore missiles reorient the seeker after launch and before before they light off their drives, giving a wide sweeping flightpath, while onbore firing is offset automatically to allow a time on target attack. The timing variance is probably automatically accounted for by the firecontrol software whenever offbore settings are used.

Jonathan_S wrote:

cthia wrote:From the location of the missile launchers, courtesy of MaxxQ, that doesn't seem plausible. The much larger Honorverse missiles have to clear the much larger external dimensions of Honorverse ships before reversing direction -- at least in consideration of reversing direction.

Also, my post was a bit unclear err inaccurate. There is a difference in net acceleration per unit time of the two broadsides. The off-bore launch has a negative acceleration of one vector component, which is momentarily, quite possibly, opposite the target.

In that worst case, 180° off bore, as Weird Harold said the facing launchers would most likely use delayed start to synchronize the salvos.

The worst case missile that might be used for this backwards firing attack would be a single drive extended range missile (ERM/LERM). The common ones of those have a 75/225 second burn (though I think the RMN's is better, but we'll got with the 225 at half power for the calculation).

1 second of burn away gets the missile out to 230 km away from the enemy, more than enough to clear the wedge. Another 0.75 seconds burning vertically will add 129 km of elevation, coming above (or below) the wedge. By this point the missile has moved 575 km away from the enemy. It'll take 2.871 seconds accelerating back towards the target to make up that distance.

But call it a total of 6 seconds lost, to allow for turning times and killing the vertical vector. The missile will have a net velocity of 861 kps towards the enemy when it passes the launching ship, and the remaining 219 seconds on its drive will let it reach 11,219,515 km, with 101,601 kps terminal velocity.

That little U-turn cost it 3.6% of its range and 1.8% of its terminal velocity. [11,219,515 km @ 101,601 kps vs 11,643,750 km @ 103,500 kps]. The missiles launched directly towards the enemy would need to delay spinning up their drives about 4.2 seconds in order to synchronize the 2 halves of the salvo.


The longer the missile's powered endurance the lower, proportional, the impact of 6 second U-turn would be. However even in this worst case scenario it seems well worth paying a few percent reduction in range to double the size of a salvo. (And, if you wanted less impact, you could point your nose or tail at the target so both broadsides need just a 90° turn)

Theemile wrote:I believe we've been told that EDMs (with 2nd gen offbore tech) can only be f1red ~135 degrees offbore. This is sufficient to cover the adjacent firing arcs, but not the opposite arcs. MDMs and DDM, with 3rd gen offbore, can fire 180 degrees offbore so can cover the opposite firing arc.

I think the capability is all in the engine burn times, with EDMs having the extra power to overcome their initial vector and reorient onto target, and MDMs having power to spare.

lyonheart wrote:In some Apollo attacks, the last stage is switched to 'quick' mode lasting only a minute yet travelling over 11 M km to reduce target reaction time.

Seems akin to my notion of a 'sprint mode' missile, proposed in the Sprint drive thread.

Which also supports another dangling part-a-sipple...

Query:As far as there being no way that Barricade's missiles could reach Tamaguchi, why? Textev states that Manty missiles have a lower acceleration than the Cataphracts but a much longer burn time.

Since Barricade's missiles were launched at an even lower acceleration than possible, does that not increase burn time?

The notion also seems to be supported by...

Theemile wrote:I believe we've been told that EDMs (with 2nd gen offbore tech) can only be f1red ~135 degrees offbore. This is sufficient to cover the adjacent firing arcs, but not the opposite arcs. MDMs and DDM, with 3rd gen offbore, can fire 180 degrees offbore so can cover the opposite firing arc.

I think the capability is all in the engine burn times, with EDMs having the extra power to overcome their initial vector and reorient onto target, and MDMs having power to spare.

It may also support the notion that copious amounts of drive time wasted does not have to be accepted.

cthia wrote:Query:As far as there being no way that Barricade's missiles could reach Tamaguchi, why? Textev states that Manty missiles have a lower acceleration than the Cataphracts but a much longer burn time.

Since Barricade's missiles were launched at an even lower acceleration than possible, does that not increase burn time?

The notion also seems to be supported by...

Theemile wrote:I believe we've been told that EDMs (with 2nd gen offbore tech) can only be f1red ~135 degrees offbore. This is sufficient to cover the adjacent firing arcs, but not the opposite arcs. MDMs and DDM, with 3rd gen offbore, can fire 180 degrees offbore so can cover the opposite firing arc.

I think the capability is all in the engine burn times, with EDMs having the extra power to overcome their initial vector and reorient onto target, and MDMs having power to spare.

It may also support the notion that copious amounts of drive time wasted does not have to be accepted.

Further reductions in acceleration apparently can produce modest increases in powered time, but it's usually counter-productive to do so.

Short Victorious War - Naval Weaponry wrote:A missile's effective powered flight envelope can be increased by setting it for a lower rate of acceleration, which delays burnout time on its small but powerful impeller drive. Eighty-five thousand gravities represents the maximum attainable acceleration, used for snapshots at closer ranges in order to achieve the shortest possible flight times. At this acceleration rate, the missile has a maximum powered endurance of sixty seconds, which restricts it to a powered engagement envelope (assuming target and firer were at rest relative to one another at the moment of fire) of approximately 1,500,000 kilometers and a terminal velocity of approximately 50,000 KPS. By setting the drive down to 42,500 gravities, time to burnout can be extended to 180 seconds, producing a maximum powered engagement range of 6,755,000 kilometers and a terminal velocity of 75,000 KPS. Lower accelerations are possible, but the maximum range and velocity actually begin to drop as acceleration is further reduced, and most navies adopted hardwired minimum settings in the vicinity of 42,500 g. The RMN, however, had not, as it believed there were instances in which absolute engagement range and velocity were less important than powered flight time to follow an opponent's maneuvers. All of these attack envelopes, of course, can be radically extended or reduced by the relative velocities and accelerations of the ships engaged.

[1]

And, while not so explicitly stated, it appears you don't get useful increases in drive endurance until you're down to that magic 50% setting. Even for shots well within the 6.5 - 7 million km range of an SDM we've never seen a higher power setting used; not until you get all the way down to the 1.5-1.6 million km range of a full power shot.

Also it's not possible to "overdrive" a missile wedge, you can't take it past 100% power no mater how close a target you're engaging.[2] So on a current RMN MDM you can't 'sprint' the final drive to an acceleration of more than 92,000 gees.[3]

So at most missile ranges you're going to have to live with wasted drive time.

------
[1] Since SVW the full power for most missiles has crept up to 92,000 gees, so half power is now 46,000. But the 60/180 second endurance per drive has not changed for most missiles - ERMs have obviously managed to increase it to at least 75/225 but again dropping below 50% power apparently still produces reductions in range, you lose from acceleration faster than you gain in drive endurance

[2] Well, for a given tech level a CM drive is overpowered, but the tradeoff to get that robustness is you can't adjust power settings -- it'll always be its 100%.

[3][size=75](Note the 4 drive Apollo based RMN system defense missiles have a CM derived 4th drive which will be quicker, but as mentioned above you can't lower it's accel to increase endurance)

cthia wrote:Query:As far as there being no way that Barricade's missiles could reach Tamaguchi, why? Textev states that Manty missiles have a lower acceleration than the Cataphracts but a much longer burn time.

Since Barricade's missiles were launched at an even lower acceleration than possible, does that not increase burn time?

The notion also seems to be supported by...

Theemile wrote:I believe we've been told that EDMs (with 2nd gen offbore tech) can only be f1red ~135 degrees offbore. This is sufficient to cover the adjacent firing arcs, but not the opposite arcs. MDMs and DDM, with 3rd gen offbore, can fire 180 degrees offbore so can cover the opposite firing arc.

I think the capability is all in the engine burn times, with EDMs having the extra power to overcome their initial vector and reorient onto target, and MDMs having power to spare.

It may also support the notion that copious amounts of drive time wasted does not have to be accepted.

Jonathan_S wrote:Further reductions in acceleration apparently can produce modest increases in powered time, but it's usually counter-productive to do so.

Short Victorious War - Naval Weaponry wrote:A missile's effective powered flight envelope can be increased by setting it for a lower rate of acceleration, which delays burnout time on its small but powerful impeller drive. Eighty-five thousand gravities represents the maximum attainable acceleration, used for snapshots at closer ranges in order to achieve the shortest possible flight times. At this acceleration rate, the missile has a maximum powered endurance of sixty seconds, which restricts it to a powered engagement envelope (assuming target and firer were at rest relative to one another at the moment of fire) of approximately 1,500,000 kilometers and a terminal velocity of approximately 50,000 KPS. By setting the drive down to 42,500 gravities, time to burnout can be extended to 180 seconds, producing a maximum powered engagement range of 6,755,000 kilometers and a terminal velocity of 75,000 KPS. Lower accelerations are possible, but the maximum range and velocity actually begin to drop as acceleration is further reduced, and most navies adopted hardwired minimum settings in the vicinity of 42,500 g. The RMN, however, had not, as it believed there were instances in which absolute engagement range and velocity were less important than powered flight time to follow an opponent's maneuvers. All of these attack envelopes, of course, can be radically extended or reduced by the relative velocities and accelerations of the ships engaged.

[1]

And, while not so explicitly stated, it appears you don't get useful increases in drive endurance until you're down to that magic 50% setting. Even for shots well within the 6.5 - 7 million km range of an SDM we've never seen a higher power setting used; not until you get all the way down to the 1.5-1.6 million km range of a full power shot.

Also it's not possible to "overdrive" a missile wedge, you can't take it past 100% power no mater how close a target you're engaging.[2] So on a current RMN MDM you can't 'sprint' the final drive to an acceleration of more than 92,000 gees.[3]

So at most missile ranges you're going to have to live with wasted drive time.

------
[1] Since SVW the full power for most missiles has crept up to 92,000 gees, so half power is now 46,000. But the 60/180 second endurance per drive has not changed for most missiles - ERMs have obviously managed to increase it to at least 75/225 but again dropping below 50% power apparently still produces reductions in range, you lose from acceleration faster than you gain in drive endurance

[2] Well, for a given tech level a CM drive is overpowered, but the tradeoff to get that robustness is you can't adjust power settings -- it'll always be its 100%.

[3][size=75](Note the 4 drive Apollo based RMN system defense missiles have a CM derived 4th drive which will be quicker, but as mentioned above you can't lower it's accel to increase endurance)

Duly noted Jonathan. Thanks. To be sure we're on the same page, is that to say that Barricade's missiles -- traveling with less than maximum acceleration -- could not have been boosted to max., after their deed was done?

cthia wrote:[
Duly noted Jonathan. Thanks. To be sure we're on the same page, is that to say that Barricade's missiles -- traveling with less than maximum acceleration -- could not have been boosted to max., after their deed was done?

Not unless they’d accomplished the Barricade intercept using n-1 of their drives.

If the Barricade's missiles are running at a less than maximum power setting, they are going to have a much longer burn time even if they don't reach the theoretical max speed possible.
Tamaguchi is heading directly at the Barricade weapons at a really good speed.
Given that Tamaguchi and the RMN weapons were on reciprical courses, they are going to bring the weapons into engagement range of Tamaguchi.
Presuming the weapos have any power left to maneuver, even if it is only to re-orient the warheads and tigger the laser-heads-(it doesn't have to put new velocity on the missles)- Tamaguchi is going to fly into that engagement range just by continuing to chase Tremaine.
If the Barricade missils don't have any flight time left on them or even if they "only" shut down their drives, if his tactical systems isn't tracking them as potential threats, he would be going to have a rude shock when the next time he is notified of their presence is warheads going off, probaby ripping chunks out of his ships.
We don't see anything about Tremaine doing anything with the Barricade missles after the fly-through with the SLN volley but presuming he (or his tactical section) knows he will have at least passing shots at Tamaguchi at some point, why wouldn't he set that up? Any warhead you get withing engagement range of an enemy target should be used to best effect. This isn't to say that he didn't have that as part of the operation, but it is POSSIBLE that the Barricade weapos would not have gotten to Tamaguchi before the "demonstration" volley against the one BC and once Tamaguchi had surrendered the Barricade shots could have been scuttled before they engaged him.

Brigade XO wrote:If the Barricade's missiles are running at a less than maximum power setting, they are going to have a much longer burn time even if they don't reach the theoretical max speed possible.
Tamaguchi is heading directly at the Barricade weapons at a really good speed.
Given that Tamaguchi and the RMN weapons were on reciprical courses, they are going to bring the weapons into engagement range of Tamaguchi.
Presuming the weapos have any power left to maneuver, even if it is only to re-orient the warheads and tigger the laser-heads-(it doesn't have to put new velocity on the missles)- Tamaguchi is going to fly into that engagement range just by continuing to chase Tremaine.
If the Barricade missils don't have any flight time left on them or even if they "only" shut down their drives, if his tactical systems isn't tracking them as potential threats, he would be going to have a rude shock when the next time he is notified of their presence is warheads going off, probaby ripping chunks out of his ships.
We don't see anything about Tremaine doing anything with the Barricade missles after the fly-through with the SLN volley but presuming he (or his tactical section) knows he will have at least passing shots at Tamaguchi at some point, why wouldn't he set that up? Any warhead you get withing engagement range of an enemy target should be used to best effect. This isn't to say that he didn't have that as part of the operation, but it is POSSIBLE that the Barricade weapos would not have gotten to Tamaguchi before the "demonstration" volley against the one BC and once Tamaguchi had surrendered the Barricade shots could have been scuttled before they engaged him.

I share your logic completely and I simply cannot figure out why Barricade's missiles weren't reused. They had everything going for themselves. No need for me to restate the obvious, as you've done a fine job.

Also, if Barricade's missiles would have been pressed for drive time, after passing through the SLN launches, couldn't they have gone ballistic themselves after revectoring? Then their drives could have been brought back up at max. accel?

lyonheart wrote:Was it Honor or Mike who was thinking about how clever Scotty and Horace had been?

Thanks for reminding me of this lyonheart. ISTRI2. Can anyone pinpoint the coordinates of this reference?

I would imagine that Honor is going to discuss the reuse of Barricade's missiles with him at a later date. As well as projecting any advantages of its use in conjunction with Keyhole II.

.

Off-bore launches from Pearls of Weber.

A real life counterpart...

Start of the 21st century missiles such as the ASRAAM use an "imaging infrared" seeker which "sees" the target (much like a digital video camera), and can distinguish between an aircraft and a point heat source such as a flare. They also feature a very wide detection angle, so the attacking aircraft does not have to be pointing straight at the target for the missile to lock on. The pilot can use a helmet mounted sight (HMS) and target another aircraft by looking at it, and then firing. This is called "off-boresight" launch. For example, the Russian Su-27 is equipped with an infra-red search and track (IRST) system with laser rangefinder for its HMS-aimed missiles.