New Eyes For The Super Hornet

That is why Boeing and the US Navy have engaged Lockheed Martin to provide up to 150 IRST systems, which, uniquely, will be mounted in the front of a Super Hornet centreline external fuel tank. Development work is jointly funded by Boeing and Lockheed Martin, and will see the 1820 litre tank design modified to incorporate the IRST in the front third of the tank, with the rear two-thirds remaining available for 1250 litres of fuel.

The US Navy is expected to provide over US$500m (A$530m) to fund further development and acquisition of the Super Hornet IRST in the next few months. The first production deliveries are expected in 2012 and initial operating capability (IOC) planned for 2013.

Irst Described

An IRST can passively detect and track another aircraft via its infrared signature, which is typically produced by engine exhaust, airflow across a wing’s leading edge, or even a sunlight reflection from a cockpit canopy or unpainted surface. IRSTs generally lack the accuracy of radar as they are affected by atmospheric distortion of infrared light and are restricted by bad weather, but their passive nature means an IRST equipped aircraft need not radiate energy in order to detect hostile or friendly aircraft in contested airspace.

This can be particularly useful in multi-axis offensive scenarios when being directed by AEW&C or ground based controllers (GCI), especially when operating against low observable aircraft which give minimal radar returns.

Current generation infrared targeting pods, such at the Litening AT and ATFLIR as used by the RAAF’s Hornets and Super Hornets respectively, do have some air-to-air applications, but these are limited due to the pod’s inability to automatically search for and detect, let alone track, an airborne target, and because their sensor apertures are generally optimally positioned for the air-to ground mission.

Older IRSTs such as those fitted to early US ‘Century Series’ fighters and Russian MiG-23s, MiG-29s and Su-27s don’t really have a search function, are mostly forward looking, and due to their high magnification, the use of these systems was described as being similar to looking through a drinking straw for a target. But modern systems such as those used by the Su-30/35, MiG-35 and that planned for the Super Hornet and Eurofighter can autonomously scan designated segments of airspace, alert the pilots to the presence of and keep track of multiple targets, and if sufficiently integrated with the aircraft’s other systems, can provide targeting data such as range, azimuth and bearing to air-to-air weapons such as the AIM-9X and planned AMRAAM NCADE.

IRSTs can also detect the approach of a passive missile’s heat plume and can be integrated with the aircraft’s electronic warfare and countermeasures suites to initiate warnings or automated self protection measures.

The system designed for the Super Hornet weighs 71. 3kg not counting the tank, and features a 23cm diameter sensor head which gives a field of regard of ±70 deg in azimuth and in elevation.

Irst For The Raaf?

There is currently no formal plan to incorporate the IRST into the RAAF’s Super Hornet fleet, but it remains an option.

The system is state-ofthe- art, is based on that used on the F-14D Tomcat in the 1990s and early 2000s, but also incorporates some ‘backend’ elements developed for the F-35’s EOTS (electrooptical targeting system).

“IRST is yet another addition to the Super Hornet Block II arsenal, and it will truly change the nature of the air-to-air fight,” claimed CAPT Donald Gaddis, the US Navy’s F/A-18E/F and EA-18G program manager in a recent statement. “Sensorfused data from IRST, AESA, ALR-67(v)3 digitally cued receiver and off-board information will ensure the Super Hornet Block II dominates and survives against the most challenging air threats well past 2024. ” The IRST will offer the Super Hornet a passive first look, first shoot capability; inertial tracking with a large field-of-regard search volume; programmable scan modes; hands on throttle and stick (HOTAS) pilot interface; is immune to electronic attack and RF counter‑measures; has weapons quality passive ranging; and perhaps most importantly, means there is no loss of a weapons station and a minimal loss of auxiliary fuel. The only real capability trade-off is that the IRST is not compatible with the Super’s centreline refuelling pod.

The IRST system will not yet be operational with the US Navy by the time the RAAF takes delivery of its 24 F/A-18Fs in 2010 and 2011, but should be available as an option at the RAAF’s first scheduled software/hardware Block upgrade, expected to be undertaken in 2014. It would certainly further enhance the situational awareness of RAAF Super Hornet crews who will already be benefiting from AESA, Wedgetail AEW&C and datalinking.