I think that this is a reaction to something that was perceived as lacking with current US fighter sensor suites.

F/A-18E/F To Get New Air Combat Sensor (Subscription Required)

Aviation Week & Space Technology
06/04/2007, page 30

Andy Nativi
St. Louis

Enhanced electronic warfare systems drive U.S. Navy to improve F/A-18E/F sensor suite

Printed headline: Bug Eyes

The U.S. Navy wants to upgrade its F/A-18E/Fs with an infrared search-and-track system out of concern that increasingly sophisticated electronic jamming systems could thwart the fighter’s radar system, leaving pilots “blinded” in air-to-air combat.

While the Russians have had these for decades, and they are part of the standard fit on both the Typhoon and Rafale, I believe that there have been only two combat aircraft so equipped in the US inventory, the F-106, and the F-14.

This is a recognition of the fact that our potential adversaries are aware of this.

Although the service has been upgrading the fighter’s radar, and the latest version (the APG-79 with active electronically scanned array) should have enhanced ability to nullify hostile jamming, Navy officials are worried about the proliferation of X-band electronic countermeasures systems, which could degrade radar performance. In particular, China’s expansive spending on electronic warfare equipment is being carefully monitored. The service fears this build-up could compromise their own freedom to operate in the Pacific.

Boeing would modify an external fuel tank to fit the F/A-18E/F with a centerline-mounted IRST. Lockheed Martin would provide the critical optics.Credit: BOEING CONCEPTS>

More than China, see below.

The addition of an infrared search-and-track system (IRST)–already standard on many Russian and western European fighters–would provide “spectral diversity” to the Navy. ……

As I’ve said, we are late to this game.

Boeing would modify an external fuel tank to fit the F/A-18E/F with a centerline-mounted IRST. Lockheed Martin would provide the critical optics.Credit: BOEING CONCEPTS

F/A-18 prime contractor Boeing has chosen Lockheed Martin to provide the sensor. A first prototype is set to be tested on a Super Hornet early next year through a company-funded risk reduction and capabilities demo effort. Enhanced versions of the AAS-42 electronics and optical units used on the F-14 (already available on South Korea’s F-15K) will be repackaged in a modified 480-gal. fuel tank. The equipment will also feature an off-the-shelf thermal control unit.

The fact that the South Koreans requested it for the F-15K implies that they are concerned about this very issue with North Korea.

My guess is that someone had done some analysis, and determined that if you put out a lot of power without a lot of sophistication, you can muddy the radar picture.

Boeing opted for a podded solution to save money. “Originally, we considered integrating the IRST into the aircraft fuselage, on the upper nose, or on the gunbay doors, but these solutions required significant structural, electrical and cooling system modifications and, in both cases, called for relocating existing antennas,” says Chris D. Wedewer, Boeing’s F/A-18E/F IRST program manager. “We also investigated the possibility of putting an IRST pod on the right fuselage station, opposite the fuselage-mounted Raytheon [Advanced Targeting Forward-Looking Infrared] targeting pod, but this option came with too many operational limitations in terms of field of view,” in particular when weapons are being carried, he adds.

Those limitations drove the decision to place the sensor on the centerline weapon station, traditionally the spot for the fuel tank. Since a fuel tank has already been cleared for that station, using such a device to house the IRST was seen as the next logical step. The IRST will also function as a fuel tank, with a part of a pod still able to accommodate 330 gal., Wedewer notes.

It is a fairly neat package for what I think is perceived as an immediate need.

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