This week Saab do Brasil announced yet another campaign involving F-39 Gripen fighters from Brazilian Air Force (FAB), this time testing the IRST (Infra Red Search and Track) system. During evaluations at Anápolis Air Base, Gripen registration number 4100 – used for testing and certification of the model – participated in simulated aerial combat against the veteran F-5 Tiger II and two other Gripens.
But after all, what is the IRST and what is it for? Why simulate combat just to test the equipment? These four letters, which have already become the subject of controversy within the Gripen subject at the FAB, represent modern equipment that has never been seen before in Brazilian fighter aviation.
As explained before, IRST is the acronym in English for Infra Red Search and Track, or Infrared Search and Track in free translation. This is a type of 'thermal radar', which, in a basic definition, uses infrared signature (heat) to identify and track a target, in the air or on the ground.
The great advantage of the IRST is that it is a ive sensor, that is, it does not emit any signal, unlike radars (the main sensor used in fighter aircraft) and laser rangefinders. This way, it is possible to accurately find an aircraft in the sky, without it knowing that it is being tracked. In addition to its use against aircraft, the IRST also serves to assist navigation through imaging functions. Although not a recent invention, IRST has become increasingly common in fighters, either through installation on the aircraft or through pods/pods carried externally at weapons stations.
A brief history
The IRST initially appeared in the 1950s, installed on F-101 Voodoo fighters, F-102 Delta Dagger, F-4 Phantom II and other models from the United States, mainly used to the use of the main radar, but quite limited by technology at the time, whose computers prevented them from being able to process so much information. Thus, the West preferred to invest more in the development of radar technologies and the IRST began to play a more secondary role.
But on the other side of the Iron Curtain, the view was different. The Soviets continued to install the IRST on several fighter aircraft such as the MiG-23, MiG-31 and most notably the MiG-29 and Su-27, which continued to use the sensor in newer and more current versions, such as the MiG-29M2, Su -35, Su-30 and MiG-35.
In recent years, the United States has invested in integrating IRST into legacy fighters, which never received such a system. Through the IRST-21, a pod-shaped solution, F-15, F-16 and F/A-18 were given the ability to ively track aerial targets through IR radiation. The more modern F-35 already came with the ‘factory’ sensor, in the form of the AN/AAQ-40 Electro-Optical Targeting System – EOTS.
The Europeans, in turn, have already incorporated the systems into their fighters, without the need for pods. This is the case of the Dassault Rafale, Eurofighter Typhoon and the Saab Gripen E itself, which is also the first fighter aircraft in Brazil to have this sensor. In fact, IRST in South America only in Brazil, Venezuela (Su-30MKV) and Peru (MiG-29).
Although the system has the great advantage of detecting without exposing the hunter, it also has disadvantages. The ability to clearly find and track a target can drop dramatically depending on weather conditions. Factors such as clouds, altitude and temperature affect IRST and this is always taken into by pilots using the equipment.
Gripen's IRST
The F-39 Gripen is equipped with the IRST Skyward-G, manufactured by the Italian group Leonardo. Installed in front of the windshield, the equipment weighs around 40 kilos and, according to the manufacturer, “offers state-of-the-art features […] and is based on our extensive experience in the area of IRST for airborne and naval systems.” Skyward finds targets in the air and on the ground, being able to track up to 200 different targets in Track While Scan mode, and also having other operating modes.
IRST vs FLIR
It is common to confuse IRST with FLIR (Forward Looking Infra Red), the latter being more popular and also used in civilian environments. Both are technologies based on infrared radiation. FLIR produces images of the target/object of interest to the operator and are typically used for target identification and surveillance. It is common for pods to also incorporate other equipment, such as designators and laser rangefinders.
The IRST has its information presented to the operator in the same way as a radar, through the information display. Newer IRSTs are capable of producing IR images like FLIR, favoring visual identification of targets. The same applies to more modern FLIRs, which also have IRST capability.
With information Millennium 7*, technomilitary, The War Zone
