Issues on Intercepting Hypersonic Missile.

IronsightSniper said:

Here's a post I made on another forum in regards to CIWS v.s. Supersonic seaskimmers:
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Gun-based CIWS will all fail, Russian, Chinese, American, against anything moving at Mach 2 at 10 meters altitude or lower.

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I believe you pull "facts" from that article that aren't facts after all.

First, when the article sais target track started at 7.3km, I think it means that the threat was detected before that by the search radar of Phalanx, that it cued the gun & the tracking radar and then it started to track already.
These are also just small radars that just have a short range anyway, because it's all they need.
If you're 5m above the waterline, looking at an object at the same hight, you'll se it at almost 16km away before it disappears behind the horizon. So Phalanx won't have difficulties engaging real sea skimmers at the same distance.
Unless of course there's bad weather conditions, but these will be even more challanging for the AShM.

Second, it's not a fault of the system that destruction of the threat only happens a few hundred meters away. Phalanx already is a last ditch, "close in" defense. Better there then not at all.

I have no hint at all that a Moskit has TVC. Do you have more than your exspectation that it has?

Finally, I believe that people are overstretching the advantage that an end-game maneuvering missile has against a defender, by a large margin, sometimes.

Especially with the speeds involved, turn radii will become really big, and a big, heavy missile also can only pull so many Gs.

If I got my stuff right, the picture looks roughly as follows:
A missile traveling at 815m/s (almost M2.5) in a level turn (20Gs) has a turn radius of close to 3.400m and turns almost 14 degrees per second. In the end, however, it still has to fly towards a rather small point in space, the ship. So it's maneuver options are rather limited.

In the pic below from the 3sec to impact point to the 1sec point, with the target traveling at 30kts against the missile turn, the angular difference from a gun on the ship between the two points is 12°. That means the CIWS mount has to turn at 6°/s to stay on target.

Taking a 530m/s (M1.6) missile at 20G, the radius shrinks to 1400+m and the missile turns a good 21°/s. From the 4sec to the 1sec to impact point the angle changes by 49° with the same assumptions as above. For the gun that means moving 16,5°/s.
Up & down truns will change the radii a bit, and all maneuvers will change speed (=slow down), wich in turn changes radii again.
But the # sound absolutely possibly. So (gun based) CIWSs do have their legitimacy to intercept leakers in the last moment.

I don't think physically turning the turret and barrel is the hard part. It is predicting the location of the missile 0.5~1.5 seconds into the future (for engagements at 400+meters) that is difficult for a turning missile. What the system has to do is aim a "fire hose" at a quickly and probably randomly turning fast-moving object. You can point the firehose quickly, but the water "lags" behind the pointing by the speed of the water. The object is moving at a speed which is on the same order of magnitude as the water in the fire hose. If the object turns quickly enough so that it gets out of the kill zone of the stream of water within the time it takes the water to reach it, then it comes down to luck.

Scratch said:

I believe you pull "facts" from that article that aren't facts after all.

First, when the article sais target track started at 7.3km, I think it means that the threat was detected before that by the search radar of Phalanx, that it cued the gun & the tracking radar and then it started to track already.
These are also just small radars that just have a short range anyway, because it's all they need.
If you're 5m above the waterline, looking at an object at the same hight, you'll se it at almost 16km away before it disappears behind the horizon. So Phalanx won't have difficulties engaging real sea skimmers at the same distance.
Unless of course there's bad weather conditions, but these will be even more challanging for the AShM.

Second, it's not a fault of the system that destruction of the threat only happens a few hundred meters away. Phalanx already is a last ditch, "close in" defense. Better there then not at all.

I have no hint at all that a Moskit has TVC. Do you have more than your exspectation that it has?

Finally, I believe that people are overstretching the advantage that an end-game maneuvering missile has against a defender, by a large margin, sometimes.

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1. I agree, the target was probably seen on the radars far before the Gun started to track. And yes, being 5 meters above the sea level will reduce the radar horizon to about 25 km and the Visual horizon just a few km less than that. That means that no matter how powerful your radar is, it won't be able to see over that horizon. The thing is too, that because the Moskit, Klub, or Brahmos have terminal supersonic speeds, that 25 km will be covered in less than a minute. In that time, a Gunbased CIWS might be able to shoot down 1 missile, but I have no doubt that 2 or more missiles fired in a volley will overcome a Gunbbased CIWS.

2. Of course it's not the systems fault, but being destroyed at a couple hundred meters doesn't help a ship when more than 1 missiles are fired.

3. It was more or less of a guestimation. TVC would make it easier for a Moskit to do said maneuvers, but I really wouldn't have any proof as to that.

4. I never stretched those maneuvers. Moving at Mach 2+ at 3-10 meters above sea level is what I usually advocate.

Overwhelming the CIWS would then, however, also inlcude that the missiles arraive at the engagement envelope at the exact same time. If they arrive spaced just a few seconds apart, I think the CIWS can run through additional engagement cycles. And taking into account the dynamic nature a moving ship has as a target, simultaneous arrivel of the AShMs can be achieved by coincidence if you can launch enough. But even with good attack planing it won't be easy to get there. So I believe in practice a gun based CIWS will be able to intercept more than one missile even in a volley attack.
Of course, a RAM like system will be even better, extanding the envelope a bit and allowing to more precisely allocate interceptors to targets.

Correct flight path prediction of the AShM will be the most daunting task, for sure. But then again, I still believe that such a missile is indeed limited in it's possible choices if, in the end, it still want's to hit a ship.
I'm also questioning if these big missiles really do jink agressively, or if they just make quick, hard, but stable turns. It seems kind of unnatural that a one or two ton missile would do these wild jinks just a few meters above the waterline at M2+ and still maintain the stability to hit the target. More conventional, although quick, agressive turns, would still be easier to predict.

IronsightSniper said:

True that most CIWSs manufacturers have not provided proof of the downing of a Supersonic seaskimmer like the Klub, however, I'd argue that'd be because the majority of AShM threats out there are posed by cheap, subsonic, missiles, such as a Termit or a Silkworm or an Exocet to a Harpoon.

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Then what do you call GQM-163A Coyote? It is a Mach 2.5 solid fuel ramjet target that flies at sea skimming altitudes. These are shot down with both SM-2 and RAM in exercises with regularity. Before that we used old Talos rounds, a liquid fueled ramjet of equal speed, converted into Vandal targets.

IronsightSniper said:

China also has Supersonic AShMs. But yeah, generally, we Westerners don't want Supersonics.



Yeah, me and a Russian fan boy had this argument a long time back, and we eventually concluded that if you want the maximum ranges for your missile, test them in Space! :nana:

But generally, not every missile intended for Point Defense is going to be mounted on a Mach 2 flying Fighter cruising at 20 km to try to get it's maximum range. They're usually fired low altitude (from a Ship-like platform) so generally, I take the ranges of SAMs as they are.



Of course, that is why Missile based CIWSs, in particular, the RIM-116 have more than one modes of operation, either SARH or IR, the former for bad weather conditions and BVR tracking, and the latter for terminal guidance.

Hybrid CIWSs (as far as I know, I'm actually just referring to the Kashtan/Palma), achieve what I'd say to be an above average Kill ratio by combining multiple forms of Point Defense (12 barrels on 2 guns and a missile) when compared to singular forms of Point Defense.

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Uh, no on both counts. Passive RF homing on RAM gets the missile out of the tube and in the vicinity of the incoming enemy missile so the IR or IIR seeker can acquire the target. The cover over the tube is not ejected until immediately before the missile is launched so there is no opportunity to lock a target before launch. IR or IIR, however, is far more accurate for terminal maneuvers during the end game.
Kashtan has a huge limitation. Each mount can engage only a single target at one time, as the same radar must be used for the duration of the missile engagement and then any subsequent gun engagement. It cannot engage with both missiles and guns simultaneously. RAM, meanwhile, is independent of any shipboard system, although Mk 23 TAS can cue it. Each RAM missile launched can engage different targets simultaneously, something Kastan or HQ-8 for example cannot do.

harishkumar09 said:

Bltizo has given the answers which I wanted to give. Brahmos is already deployed, mating it to SU-30 MKI should be done by the end of 2011, I don't think it is such an insurmountable technological challenge. And SU-30 MKI can fly low (30m ASL) and launch the Brahmos in lo-lo mode. It might also take out the observation helos, prior to launching and so while you can guess a salvo of Brahmos is on its way, you wont know which direction and won't have targeting data until it is very close.

When I am contesting the ability of SeaRAM or its Chinese equivalent to knock out a salvo of 40 Brahmos, I am not talking about the superiority of my weapons or downgrading the capabilities of the AEGIS or the Chinese destroyer.

I am just looking at it from the engineering perspective. Is technology mature enough to handle such a salvo? We know the maths and physics (which itself was contested by the person who began this thread), I am asking does the engineering capability exist, assuming we have 120 SeaRAMs on board ready to be launched. What are the challenges we will face? At least the RAMs have to be initially guided to their acquisition baskets before their IR seekers can lock on, plus can they maintain their lock when so many missiles interweave and criss-cross their path. This does not require swarm intelligence of any kind. They can be programmed to independently do it, though it can sometimes result in fratricide.

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Where to begin. The E-2 will see any attack aircraft long before they reach their launch points and have defending F/A-18's on the way. It is extremely doubtful a launch aircraft could get inside the carrier's air wing to the launch point of any high supersonic missile without having to fight their way through the air wing first. The E-2's would have to be shot down as well to deprive the CSG the ability to see those missiles and their launch aircraft.
AEGIS was designed to deal with a Soviet massed missile attack coming from submarines, surface shooters and Backfire/Blackjack bombers from several points on the compass at once, and can handle literally hundreds of intercepts at one time, providing mid course corrections to hundreds of outgoing SM-2's and ESSM's. The switch from SARH for the endgame of SM-2 to fully active final guidance for SM-6 greatly enhances the abilities of AEGIS as the Mk-99 GFCS will no longer be needed for the final second of the endgame, at least with Standard shots. For now at least ESSM will still require illumination of targets for the last second of the intercept.

harishkumar09 said:

I understand the division in labour in terms of frequency bands, but I was just thinking there are too few illuminators onboard the destroyers escorting the CVBG. Perhaps an AESA or PESA in the X-band could terminally illuminate more number of missiles simultaneously than all the MK99 illuminators put together.

Or alternatively go for ARH missiles, but even here we would need multiple beams to guide several of them to their acquisition baskets.

There may be a place for Mach-3 and even the Mach-5 Brahmos 1 and 2 for certain tactics in the battlefield, both land and sea, but I think India should also earnestly begin developing subsonic cruise missiles for both the land and sea roles.

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Here is how on illuminator can handle four intercepts simultaneously. Keep in mind AEGIS is data linking to these missiles as they fly out using a data link capability built into the AN/SPY-1 radar itself.
First, the four intercepts have to be in close physical proximity in azimuth and elevation, within the width of the SPG-99's narrow beam. In a mass attack that is possible. Second, each of the four missiles will be looking for reflections on different frequencies and different codes. The missile only needs illumination for 25% of the end game to get close enough for the proximity fuse to detect the target and for the warhead to take out the target. Close enough works for this. The target illumination radar can rapidly switch between up to four freqs each coded uniquely for each intercepting missile, such that each missile homes on the correct target and one illuminator can thus provide terminal illumination for more than one target at a time.
Also keep in mind that with AEGIS, the SM-2 is flying out on inertial nav to a waypoint in space fed to it from AEGIS, and updated in flight as necessary by the data link feature of AEGIS. It is only the final second or so of the flight that requires illumination of the target.
With SM-6, no target illumination will be necessary, leaving the SPG-99's free to support ESSM's at closer range to take care of the leakers.

Well, as I said in one of my posts before, the Vandal shot down (at least by Raytheon) was indeed a Mach 2.5 missile, however, it was diving and not sea skimming. As for the Coyote, I honestly don't have enough information on them to actually print a picture, but it's not as if it was doing S maneuvers :3

harishkumar09 said:

But Ambivalent, aren't missiles with active terminal homing capability very costly? Isn't it better to use target illumination from main radars? Also PESA's themselves should be capable of switching rapidly from scanning to illuminating targets, more so the AESA's and I think that is cheaper.

If Mk-99 can illuminate more than one target, and that too only when they are closely spaced, then certainly the CVBG is vulnerable to saturation attacks.

The P-700 Granit is capable of sharing information, and if they can also share information about radar reflections, they can eliminate the false positives created by decoys and more will get through. I wonder how Mk-99s with their limited capability are going to handle saturation attacks. I think AESA will be the cheap and best alternative, however, terminal active homing is even better, but very costly.




Thats where differential calculus comes in with its concept of infinitesimals. As the time intervals become shorter and shorter until they approach zero, you get the differential at that point. Therefore the interception missile always knows in advance where the initiator will be, by analyzing its rate of turn. It can then calculate in advance, and compensate for the fact it is the reactor, by turning even further. These calculations happen every instant, and thats what derivatives are all about.

The mathematics behind two intercepting missiles was figured out by Sir Isaac Newton and Libnitz some 300 years ago. So also the physics. The problems we face are purely related to engineering. How many missiles can be detected successfully, how many can we deal with simultaneously?

The way to successfully disable/destroy a CVBG would be to avoid detection and saturation.

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First off, SM-6 is coming to the fleet in about a year. It uses an AMRAAM seeker so the cost is within reason for the capability gained. SM-2 will be replaced in it's entirety with SM-6. I don't know if the existing SM-2's will be converted to SM-6 spec or sold to foreign customers. I would guess that once SM-6 reaches the fleet, they will begin looking at putting that same seeker on ESSM. Also keep in mind that AMRAAM forms the basis for the Army and Marines new ground based air defense system, SLAMRAAM. This seeker is in mass production.
Btw, Small Diameter Bomb uses a tri-mode seeker, with the semi-active laser and imaging infrared seekers sharing portions of the same optics and a millimeter wave radar similar to that in Longbow behind the optics. Brimstone 2 has a dual mode seeker with semi-active laser and millimeter wave radar integrated into one guidance and control section. Similar dual and tri-mode seekers are to follow as costs and component sizes both decrease dramatically. Multi-mode seekers will make effective countermeasures orders of magnitude more difficult.
Learn how proportional navigation works. Your calculus is interesting ( I have enough calc and diffy-Q to understand it ) but it's not remotely close to how intercepts are calculated. It is much simpler, striving to keep the angle between the interceptor and intercepted object constant at all times, adjusting the direction of flight as necessary to keep this constant angle.