The great return of IRST
A passive and discrete detection system par excellence, based on the simple search for long-distance heat sources by low-frequency thermography, Infra-Red Search and Tracking System (IRST) infrared watch is not really a novelty Combat aircraft. Invented by Texas Instruments, subsequently upgraded by Hughes, and used for the first time in Vietnam from 1967 by the US Air Force (and apparently not very effective due to a technology of semi -conductors then stammering) first on the Convair F-102A missile interceptors deployed on this theater, then shortly after on F-8 Crusader and F-4B and C Phantom II fighter aircraft, it is currently, and half a century Later, a strong comeback on current versions of the most prominent fighter planes, such as the Eurofighter, the Rafale, the F-35, the ultimate versions of the F-15, the Su-27/30 (J- 11) and other MiG-29/35 ... and recently on the new Gripen E and the new Chinese hunters (J-10/20). The main players today are Selex and Thales / Safran (formerly Sagem SAT) in Europe, Lockheed Martin and Northrop Grumman Electronic Systems in the United States, or UOMZ / Ekaterinburg in Russia.
It must be said that the technology in IR sensors and algorithmic signal filtering has made enormous progress since then, the current multi-band IR monitoring systems perceiving the heat waves much further and on a much wider spectrum Around the aircraft (or even on a 360 ° bearing with the DAS of the F-35). The IRST, without ever revealing the presence and position of an attacker, silently detects and tracks any target in short- and medium-range flight (about 100 km). Can be accompanied by an electro-optical assembly and a laser rangefinder (as on Rafale), the IRST is in the form of a translucent ball mounted permanently on the nose of the plane, just in front of the canopy Of the pilot above or below the radar, but also now as a point of a removable nacelle that can be carried under the fuselage. Associated with new generation radars, an IRST system adds greatly to the capabilities of a combat aircraft, its IR information can be merged with that of other sensors present on the cell to give the pilot an overall vision likely to be Directly projected on the helmet visor (Helmet Mounted Display), to give him the best capabilities of action and reaction in air combat.
They are called SkyWard (on Gripen E), Pirate (on Eurofighter), OSF (on Rafale) OLS-UE (on MiG and Sukhoi) or AN / AAQ-37 DAS (on F-35) IRST now seem inescapable on the most prominent combat aircraft of the moment, particularly because they are efficient and insensitive to electromagnetic interference. As a complement to a radar that sees further - and gives information on the speed of a target by the Doppler effect - these highly improved IR monitoring systems are also undeniable marketing tools when it comes to For an aircraft manufacturer to sell its hunters abroad. The new AN / AAS-42 "Tiger Eyes" from Lockheed Martin, now on the F-15E Strike Eagle export versions (F-15QA, F-15SG, F-15K, F-15SA) Or at the front tip of the F / A-18F Super Hornet ventral reservoir or in the form of the "Legion pod" (the size of a 250 kg bomb ) Adaptable to any type of fighter - in the manner of a nacelle of laser designation or recognition.
Paradoxically in France, it seems that the choice was made by the DGA to renounce, on the future variant F4 of the Rafale, the fixed IR track as successfully used on the current OSF. Based on the experience gained from operations carried out in recent years by Rafale Air and Marine and the evolution of weapon systems elsewhere in the world, it is with the future Talios High Resolution Multifunctional Laser Designation Platform ( TArgeting Long-range Identification Optronic System) of Thales, which is currently being tested and scheduled to enter service next year, that it will be possible in the future for a Rafale to pursue targets in IR mode as well Although to acquire them in air and air-to-ground mode and to complete their identification at a great distance by means of a color TV HD channel, in addition to the OSF IT that will replace the current OSF. The DGA has already ordered Thales twenty of these nacelles, out of a total envisaged forty-five pods for the Air Force and the Navy.
