2009/03/20

ARM in anti-ship combat

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The German navy operated a wing of Tornado IDS multi-role combat aircraft until 2005. The wing had a dedicated maritime mission; maritime reconnaissance, anti-ship combat and attacks on harbours if I remember correctly.


The transfer of this mission to the Luftwaffe (air force) was not unanimously greeted, one concern was that the training for the maritime missions would suffer and the competence for this mission decline.

This resulted in an interview of the last wing commander in a civilian journal. Such interviews are usually a lot of blablabla with next to no really interesting information. This interview was different. In order to make his point (the need for dedicated maritime raining of aircraft crews) he described the anti-ship attack tactic, and that was interesting for a change. It's thus now OK to write about this publicly.

The tactic included three munitions;
1) the Kormoran2 anti-ship missile (quite comparable to Exocet, Sea Eagle, Harpoon and most other Western anti-ship missiles).
2) The AGM-88 HARM anti-radiation missile
3) bombs

He claimed that it takes all three to sink a ship and that a very challenging synchronized attack with the subsonic anti-ship missile and the smaller supersonic anti-radiation was necessary to overwhelm the defence for a firepower kill. The bombs were just meant to deliver the killing blow.

This is indeed a rather difficult profile (especially the timing), and apparently well-suited for the limited quantity of available munitions (the attack would not have a whole squadron vs. a destroyer, of course).


This begs the question why there's (officially) no anti-radiation missile component in anti-ship attack capabilities of surface combatants and submarines (which can also launch special versions of Harpoon and Exocet)?

The typical armament is like four Exocets or eight Harpoons per surface combatant, and a submarine will not be able to launch more than six Harpoon or Exocet in a short time either.

Anti-ship missiles of the dominant design (radar + subsonic + sea skimming) have been in service since the 1970's - all modern navies had plenty time to introduce proper countermeasures and major changes occurred only in the electronics (addition of home-in jam, better manoeuvring, smarter target ID and choice).
The NSM missile from Norway (infra-red sensor instead of radar, like the old Penguin missile family) and the Hsiung Feng2 missile from Taiwan (IR sensor additional to radar) are rare exception to the rule.

There's no equivalent combination of ARM and AShM (anti-radiation missile and anti-ship missile)

Anti-ship missiles like Harpoon are much slower and longer-ranged than anti-radiation missiles. It could be impossible for surface combatants to launch both against the same target.

This begs another question: Why not combine both?

The ARM could become a submunition of the larger AShM; to be dropped a few nautical miles ahead of the target area to suppress the target's radar. A variable thrust ARM would be quite good for this - just like in other SEAD (suppression of enemy air defences) situations.

The anti-ship missile armament of surface combatants looks quite neglected to me, not really well-designed to do the job. Neither quantity nor quality of the missiles are fully convincing to me. It's almost as with anti-submarine warfare; the effort seems to concentrate on air-delivered munitions, with rather mediocre offensive capability built into the ship itself.

S O

P.S.:
Hsiung Feng 2's approach of dual sensors makes a lot of sense, too - but that's just about proper targeting, not so much about survivability (although an anti-ship missile that locks on one decoy after another while being shot at by a nearby ship's close-in weapons is likely unable to survive long enough to do its job!).
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4 comments:

  1. I like the idea of an ARM piggy-backed onto a longer range anti-ship missile. Is the idea of the ARM to destroy targeting systems for anti-ship missile defences?

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  2. An ARM (the relatively light Shrike) has hit a U.S. warship in the Vietnam war (an accident) and did considerable damage to the radars (total firepower kill for hours if I remember correctly).
    More modern ships should be designed to be less badly hurt, but ARMs are still the weapon of choice to hit or destroy radar.

    Their utility lies more in suppression (force the radar operator to shut the radar off for a while) than in destruction, though.

    The ARM/AShM combination was meant to increase the hit chance of the AShM, mostly by suppressing the defender's radar. That doesn't do much to infrared sensor-based close-in weapon systems (especially RAM), though.

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  3. For launching an ARM, you need a direct view on the targeted radar and that this radar is on. This can only happens at very short range between 2 ships. Anti-ship missiles are more flexible because they don't rely on the good will of the target to keep its radar on. Moreover, modern anti-ship missile usually rely on a deported sensor for acquisition, usually the frigate's helocopter. Anti-ship missile can cruise at low altitude and thus make surprise attack at wave heigth. On the contrary an ARM will have to use a high altitude trajectory to see the target radar. The target has thus a lot of time to react to intercep it or turn its radar off.

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  4. I believe you didn't get why the combination of ARM and AShM is effective.

    "The target has thus a lot of time to react to intercep it or turn its radar off."

    That's the point. interception is difficult because ARMs are faster and smaller due to a smaller warhead AND shutting the ships' radar off is the point of the exercise.
    An inactive radar doesn't help against the near-simultaneous approach of the AShM any more.


    So you don't need a LOS to the ship or an active ship radar for the ARM employment at all. Instead, there is (assuming the ARM is faster than AShM; not necessarily true with the Alarm ARM) only one requirement: You need to have a good idea about the distance to the target. The knowledge about the distance allows the computing of the required delay between the AShM and ARM launch.

    A combination (ARM as daughter of the AShM) would delete even this requirement, for only the combination missile needs to know the distance in time.

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