Terminal guidance question

Just recalled something from Honorverse. During the course of the series, numerous times missiles were diverted from the target by warship's countermeasures systems, decoys, ect.

But I could not recall any instance, when the missile, that penetrated anti-missile defenses - missed the ship with its laser warhead.

Which represent sort-of a problem. We knew that missiles could be fooled, diverted (in short, soft-killed) by ECM's during their cruise flight. But it seems that as soon as missile get close enough to hit ship with its laser warhead - which is LONGER than the usual hit distance, because the distance is determined by the warhead ability to burn through sidewalls - ECM's suddenly stopped to work at all. And only hard-kill systems remains.

Which is strange, because missiles, as I mentioned above, could be soft-killed while cruising. And during cruising, the missile goal is pretty simple - to get near the ship - and thus must be pretty ECM-resistant (in fact, during cruising the missiles should not be susceptible to ECM's at all - because they knew where is their parent ship and should just ignore anything that didn't come in tight beams from exactly that direction).

But during the terminal guidance, the missile is forced to solve MUCH more complex problem - to hit the fast-moving target, half-obscured behind the sidewall, while being near-relativistic. Not only the microsecond delay would led to an absolute and clear miss, if the missile is moving at 0,83c, but all the missile own systems are slowed down more than twice because of time dilation. And yes, the missile have only a very limited time to aim & burst, or defense lasers would took it out.

So why no one is trying to soft-kill the missile at terminal stage? By confusing her rangefinders, for example? If the missile would made a slightest mistake in calculating the target exact position, it would miss the target completely.

It could be as simple as the author choose not to write about misses because it's more interesting to read about the hits.

Misses are described fairly often, most recently in Uncompromising Honor, during the battle for the Prime-Ajay terminus. Furthermore, the whole point of the laser head missile is that many - even most - of the laser heads will miss, but you're generating more attacks that the aggregate hit probability is decent.

Joat42 wrote:It could be as simple as the author choose not to write about misses because it's more interesting to read about the hits.

Well, possibly) But frankly, the number of missiles, that missed/get soft-killed at terminal stage must be MUCH bigger than number of missiles that were soft-killed during cruise.

Duckk wrote:Misses are described fairly often, most recently in Uncompromising Honor, during the battle for the Prime-Ajay terminus. Furthermore, the whole point of the laser head missile is that many - even most - of the laser heads will miss, but you're generating more attacks that the aggregate hit probability is decent.

Frankly, it wouldn't work like that. Not on near-relativistic velocity. Your "laser shotgun" either aimed correctly as whole, or in would miss entirely. We are talking about near-relativistic velocities. Besides, having several laser rods just make situation more complex for guidance system, because it is forced to make SEVERAL absolutely correct prediction while working under time dilation effects.

Dilandu wrote:

Duckk wrote:Misses are described fairly often, most recently in Uncompromising Honor, during the battle for the Prime-Ajay terminus. Furthermore, the whole point of the laser head missile is that many - even most - of the laser heads will miss, but you're generating more attacks that the aggregate hit probability is decent.

Frankly, it wouldn't work like that. Not on near-relativistic velocity. Your "laser shotgun" either aimed correctly as whole, or in would miss entirely. We are talking about near-relativistic velocities. Besides, having several laser rods just make situation more complex for guidance system, because it is forced to make SEVERAL absolutely correct prediction while working under time dilation effects.

Nonetheless, that is exactly what is described numerous times in the novels. Each independent laser rod has an aiming system separate from the others such that they're all aimed roughly by the missile's terminal bus but then fine-tuned by the laser rod sensors. At a typical 30k km standoff range, the difference between hitting a ship and missing by a kilometer is less than 0.002 degrees, or less than a millimeter difference in aiming at the laser rod end.

Dilandu wrote:But I could not recall any instance, when the missile, that penetrated anti-missile defenses - missed the ship with its laser warhead.

In almost every battle, there is a detailed count of missiles fired, missiles destroyed, missiles wasted against wedges, x-ray beams diverted by sidewalls, near misses, and solid hits.

Joat42 wrote:It could be as simple as the author choose not to write about misses because it's more interesting to read about the hits.

And IIRC some of them are described as being bent by the sidewall; but I don't recall whether or not we ever had a complete miss described.

But as others pointed out a laserhead is usually aiming 5-10 lasing rods at the most probably locations the ship might be. If the ECM was totally ineffective every one of those lasers would score. Often though only 1 or 2 from a laserhead seem to hit.


And finally most recent missile combat discriptions have involved dozens of laserheads going off nearly simultaneously against a given target. So many dozens of lasers flying around. If a ship takes 10 hits from a salvo where 12 Mk23s reached attack position then its terminal ECM fooled 91.6% of that final attack (110 lasing rods of 120 missed). But the way the combat it written in agrigate it's hard to know how many lasing rods engaged the target vs how many hit. Some missiles were probably totally fooled and every one of their rods was aimed slightly wrong - but it's a numbers game and very hard to fool all the guesses, even with a sidewall obscuring the exact location of the ship, from as close as 30-50,000 km.

Dilandu wrote:Just recalled something from Honorverse. During the course of the series, numerous times missiles were diverted from the target by warship's countermeasures systems, decoys, ect.

But I could not recall any instance, when the missile, that penetrated anti-missile defenses - missed the ship with its laser warhead.

Which represent sort-of a problem. We knew that missiles could be fooled, diverted (in short, soft-killed) by ECM's during their cruise flight. But it seems that as soon as missile get close enough to hit ship with its laser warhead - which is LONGER than the usual hit distance, because the distance is determined by the warhead ability to burn through sidewalls - ECM's suddenly stopped to work at all. And only hard-kill systems remains.

Which is strange, because missiles, as I mentioned above, could be soft-killed while cruising. And during cruising, the missile goal is pretty simple - to get near the ship - and thus must be pretty ECM-resistant (in fact, during cruising the missiles should not be susceptible to ECM's at all - because they knew where is their parent ship and should just ignore anything that didn't come in tight beams from exactly that direction).

But during the terminal guidance, the missile is forced to solve MUCH more complex problem - to hit the fast-moving target, half-obscured behind the sidewall, while being near-relativistic. Not only the microsecond delay would led to an absolute and clear miss, if the missile is moving at 0,83c, but all the missile own systems are slowed down more than twice because of time dilation. And yes, the missile have only a very limited time to aim & burst, or defense lasers would took it out.

So why no one is trying to soft-kill the missile at terminal stage? By confusing her rangefinders, for example? If the missile would made a slightest mistake in calculating the target exact position, it would miss the target completely.

The main reason there is no spoofing a missile once it is on its terminal run is that there is no time to do it!

The terminal run is actually a cone that takes in account 'jinking' to reduce the effectiveness of counter-measures

If you remember counter-measures are two layers with the inner layer being lasers. Once a missile gets to the inner layer there is no time for it to be acquired more than once by a single laser. Up until the missile does its terminal lock it is free to 'jink'. The better missile systems will be designed to not lock up until it is within the inner defense envelope.

Once the missile acquires its terminal lock, its no longer bothering with e-m detection; it has mapped the grav gradients of the target, makes a final course correction to optimize the attack profile, begins orientation rotation of the rods (most likely by rod package release to allow for maximal rod maneuver), then detonates the pump bomb at the optimal time along the trajectory. This literally takes micro seconds. (c = 300,000 km/sec: then .8 c covers .24 km in 1 micro sec or 12 km in 50 micro secs).

In reality one could deploy reactive armor (disperse a particulate cloud around the ship) or ablative armor but the main problem with those is that they have to be 'reset' after use. Plus, with HV physics, what's the point; the wedge, side walls, et al are far superior to material armor and does not have to be reset.

One could conceive of a third counter-measure layer that launches particulate/flak/chaff mortars (bursting charges) but getting the coordination down between the 2nd & 3rd layers would be a real bear and it would complicate munition carrying capacity. My guess is, because it breaks the KISS principle it would be unlikely to be deployed.

-David S.

dsrseraphin wrote:Once the missile acquires its terminal lock, its no longer bothering with e-m detection; it has mapped the grav gradients of the target, makes a final course correction to optimize the attack profile, begins orientation rotation of the rods (most likely by rod package release to allow for maximal rod maneuver), then detonates the pump bomb at the optimal time along the trajectory. This literally takes micro seconds. (c = 300,000 km/sec: then .8 c covers .24 km in 1 micro sec or 12 km in 50 micro secs).

For that, the missile must knew the target exact position (and I'm not sure that target at relativistic velocities even HAVE exact position!) with the very high level of precision, using only missile own sensors while her systems reaction time are slowed by time dilation. There are SO many things that could go wrong...

And again, how exactly the missile pinpointed the ship? I recall that in Infodumps it was stated that ship could shift its position inside the wedge (at least a bit), so the exact characteristics of the wedge would not give the exact location of the ship. So the missile must use some kind of sensors, that might be spoofed a bit (and "a bit" here means "clear miss")