Is the large Missile Destroyer/Cruiser becoming obsolete?

Scratch said:

Actually, water vapor is really effective at absorbing IR wavelengths. (And least effective in the visual spectrum.) And I would think that especially close to an ocean surface, there is an increased amount of water vapor.

IR seekers are used in BMD because they provide a higher resolution / accuracy then RF seekers due to the shorter wavelength, wich is crucial at the high closing speeds involed. I also don't think that the range of RAM outperforms it's IR sensor.

Yet, I do believe that at least for the close in defense a IR seeker is the best solution, esp. when backed up by passive RF.

I also think a multi sensor approach in attack missiles has it's merits, exploitung the full spectrum. One may not even have to have multiple sensors on one missle, but have many missiles with different seekers and have those missiles communicating with each other.

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The trend in the west is to put multiple sensors on each missile, such as one finds on SLAMER and Kongsberg's Naval Strike Missile. The electronics are small enough now to make this practical.
Longer wavelength IR, 8-12 microns, penetrates clouds or haze with greater intensity than visible light. Some supersonic missiles also have such a strong IR plume the IR sensors can often detect them before the ship's radar, while the missile itself is still below the horizon and navies are adopting IRST's on ships to aid detecting these. Still, the missile's own seeker is usually the first clue something is headed your way. A ship's ECM, such as the SLQ-32 will pick up the inbound missile's emissions and cue the RAM to launch. The RF detector is supposed to guide the missile until the IR sensor locks, but RAM can home using IR from launch if the IR plume is sufficient. Block 2 has twice the propellant as previous versions, so a range increase is certain, but there is no open source data. IR is interesting, those dark tinted looking lenses on IR missiles are actually more transparent to IR than clear glass or plastic.

Ambivalent said:

No, not really. If, for example, your ship is engaged by the anti-radiation homing version of C-802 the IR seeker is crucial. The missile itself will have no RF emissions on which the ship's missile can home in on. Likewise, supersonic missiles such as 3M80 and Kh-31 are very hot due to skin friction, making IR homing very reliable when engaging these. This is why RAM relies primarily on IR homing but has an RF back up guidance, integrating information from both for a guidance solution.
Btw, notice most US missiles used to counter ballistic missiles, such as THAAD, SM3 use IIR guidance. It is most reliable in space.

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It is used in space, not because of "space" but because of orbital velocities. When you reach a certain speed, radar doesn't have the precise resolution to track the speeding object as good as infrared with the level needed for a direct kinetic hit.

RAM has an RF seeker to allow intercepts at greater range than the IR seeker has, allowing what appears to be a lock on after launch capability for this missile's IR seeker. Notice RAM Block 2 has a much larger rocket motor than previous versions had.
In space however, IR and IIR seekers have outstanding performance and have become the preferred seeker for the BDM mission.

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RAM uses passive interferometers. It basically locks against the target's own RF emissions, which has the frontal view against the rear emissions of the infrared.

crobato said:

It is used in space, not because of "space" but because of orbital velocities. When you reach a certain speed, radar doesn't have the precise resolution to track the speeding object as good as infrared with the level needed for a direct kinetic hit.



RAM uses passive interferometers. It basically locks against the target's own RF emissions, which has the frontal view against the rear emissions of the infrared.

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RAM Blocks 0 and 1 use those and a reticle IR seeker based on the seeker from Stinger. RAM Block 2 uses a staring focal plane IIR seeker.