Quite Special And Not At All Boring


Bragging is not a Swedish character trait. Indeed, self-deprecation is a national pastime. Where else would a pop lyric begin: 

I'm nothing special. In fact I'm a bit of a bore. 

According to this tradition, Saab has let information out in dribs and drabs about the next-generation Gripen, now dubbed JAS 39E, since the existence of the Demo program was revealed in 2006. Last week's media briefings in Linkoping answered a few questions. The fighter's airframe and most of the hardware is all new. On the other hand, there are no dramatic external radar-cross-section (RCS) related external changes (as had been speculated from time to time). And while the latest media briefings went into detail about the engineering discipline that is expected to reduce development costs by at least 40 percent, relative to the rather simpler JAS 39C/D program, there was little said about the new cockpit, or the electronic warfare system. However, the much enlarged wingtip antenna/launch rail assemblies indicate big changes in that area. 

It took a Scot, Selex-ES' Bob Mason, to make one of the most dramatic claims, confirming on the record what's been talked about quietly for a few years: state-of-the-art infrared search and track (IRST) systems can detect and track stealthy aircraft at the kind of ranges associated with beyond-visual-range engagements, whether or not they are using afterburner. 

IRST has a spotty history. F-4s and F-106s were equipped with primitive units and Russia included IRST on the MiG-29 and Su-27 families. The U.S. Navy developed IRST for the F-14D Super Tomcat, mainly as a counter to the formidable jamming system on the Tu-22M Backfire. The same hardware was slated for F-22 but discarded in an early budget scrub. In the West, that left Typhoon (Selex) and Rafale (Thales, built into the front sector optronics unlt) as the standard-bearers. More recently, the U.S. Navy has started working on IRST for the Super Hornet, initially with optical hardware from the F-14D days, and Aggressor F-16s have been seen with IRST pods. Selex and others have developed surface-to-air IRSTs.

Early systems had limited range. This had less to do with basic physics and IR technology than with false alarm rates: the IR world is a noisy one, and if the system gain is turned up too high it will detect birds, the sun reflecting off clouds, ground vehicles and everything else. Faster processing and the ability to record and analyze a great deal of IRST data has gradually whittled away at the problem -- and progress in the last few years (according to Eurofighter and other sources) has been rapid.

Hiding from IRST is difficult for anything flying much above 300 knots. There have been isolated reports that the F-22 uses an active cooling system to deal with hot-spots at high speed, but that raises problems -- the heat has to go somewhere. 

Like Russia's work on advanced VHF radars, IRST does not mean that stealth is dead. However, it does raise the bar for stealth, particularly in an air-to-air engagement. It makes it more difficult for a low-RCS fighter to engage its adversary without being detected itself -- if both are using IRST, detection may be mutual. (At the same time, the much better electronic warfare systems on modern flighters have redefined "low probability of detection" for a stealth attacker's radar.) 

The F-35's electro-optical targeting system (EOTS) is described as having an IRST function. However, like other air-to-ground targeting sensors, it operates in the IR mid-wave band; IRST uses long-wave IR, which is better at long range. Neither is it optimised for the kind of very rapid "step-stare" scanning that an IRST uses to cover a wide area. 

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