2017/02/22

Cooperative engagement capability and ARH missiles

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I wrote for years about how a radar (even a radar of an AEW aircraft) can be used to direct a missile launched from a remote platform (ground vehicle, ship, aircraft) to the vicinity of a hostile aircraft where the missile's own sensor locks on the target and guides the missile during the terminal homing phase.

Now, somewhat belatedly, I noticed that I never really told readers about the terminology for this.

One relevant keyword is "Cooperative Engagement Capability" (CEC), and the more general buzzword is of course "network-centric warfare" (NCW).

The entire thing rests heavily on digital datalinks (typically "Link 16"), but analogue systems to guide manned interceptors to the vicinity of bombers existed already back in the 1940's and were quite sophisticated by the 1950's. Early digital systems appeared in the 1960's (example; Swedish "STRIL 60"). I was astonished when I learned that the U.S. Navy didn't test some early kind of CEC ability with missiles guided by another platform than the launch platform until well into the 1990's, for I had simply assumed that this had been a feature of AEGIS since the 80's. It seemed to be a no-brainer to me that illumination radars of multiple ships should be available for missile terminal homing guidance.

Readers might have noticed that I often do not suppose that sensor and weapon need to be united on one platform or in one battery. Artillery began to give this up prior to the First World War, when it detached forward observers who communicated with howitzer batteries via field telephone (cable). Warships did this a little later, with aircraft observing fall of shot (particularly in coastal bombardments).
It still feels intuitive and self-evident that a surface-to-air missile system needs to have a matching sensor (radar) to form a battery with launcher+control cabin+sensor, but it's not self-evident at all.

The availability of lock-on after launch (LOAL) sensors on missiles enables us to use somewhat imprecise sensors that do not need need to deliver very exact vectors to and of the target vehicle. The 'footprint' of the missile's seeker can find the target if only the missile is directed to fly approximately to the target and arrives in its vicinity for its own sensor to take over.

Another important step was to leave semi-active radar homing (SARH) behind; this required powerful radar emitters that "illuminated" the target, so the missile with its passive radar seeker could track the target by the reflections. The switch to active radar homing (ARH) and passive (usually infrared) homing seekers allows to get rid of the huge illuminating radar.
Fighters can now turn and run away after launching their missiles at the target. This way they run away from the target's missile shots and the friendly missiles may still get midcourse updates (from other fighters, even if those are too far away fro SARH illumination) to find the target by another fighter that didn't turn. 1990's and later fighters (Gripen, Typhoon, Rafale) tend to have this kind of cooperation capability.

The good news are
  • we don't need to spend as much on land-based and warship radars any more
  • our SAM batteries aren't easily suppressed or knocked out by attacks on their radars any more since they may not even have a radar
  • warships without anti-air warfare specialisation may now still be hugely capable in AAW
while the bad news with all this are
  • air war depends even more on radio communications (datalinks) than before
  • missiles are more expensive because ARH is expensive
  • we should spend more on survivable AEW assets (and should find a better acronym than "AEW")
  • opposing forces' area air defences may also be highly resilient if designed to function without and organic emitting radar

related:

external links:
Under the NIFC-CA ‘From the Air’ (FTA) construct, the APY-9 radar would act as a sensor to cue Raytheon AIM-120 AMRAAM air-to-air missiles for Boeing F/A-18E/F Super Hornets fighters via the Link-16 datalink. Moreover, the APY-9 would also act as a sensor to guide Raytheon Standard SM-6 missiles launched from Aegis cruisers and destroyers against targets located beyond the ships’ SPY-1 radars’ horizon via the Cooperative Engagement Capability datalink under the NIFC-CA ‘From the Sea’ (FTS) construct. In fact, the Navy has demonstrated live-fire NIFC-CA missile shots using the E-2D’s radar to guide SM-6 missiles against over-the-horizon shots—which by definition means the APY-9 is generating a weapons quality track.





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