Su-57’s “distributed radar” must radiate electromagnetic waves outwards to work, equivalent to a person walking at night with flashlights all over his body, making it easier to be spotted.
Restricted by backward microelectronics technology, Russian radar has been wandering in the field of the passive phased array for a long time, and its active phased array radar has been unable to get rid of the state of experimentation. As early as 15 years ago, MiG-29 has equipped with Beetle AE phased array radar, but it is still not fully practical. But Su-57 finally reversed this trend. It was not only equipped with phased array radar but also installed five at once.
The five radars are the N036 forward-looking X-band main fire control radar with the nose nicknamed “Squirrel”, two N036B X-band side-looking radars on both sides of the nose, and two N036Ls on the movable leading-edge flaps. Type L-band phased array radar. The introduction of five radars onboard Su-57 just exposed Russia’s lack of confidence in its stealth capabilities.
Without powerful computers and software, there will no data fusion to assist pilots in situational awareness. There is no helmet-mounted display for Su-57 either. In short, a pilot has to look at five different instruments to figure out whether his/her aircraft has been targeted by adversary EW equipment or missiles.
The N036 radar antenna is elliptical, 0.9 meters long and 0.7 meters wide, and has more than 1,500 T/R components. The total power is 18,000 watts based on the power of 12W for each antenna. However, considering that the active phased array radar has the advantages of high efficiency and low loss, its power should not be lower than that of the “Snow Leopard”-E radar. The theoretical maximum detection range of N036 also exceeds the latter, up to 250 kilometres. But 1,500 transceiver units are not as many as the F-35 APG81, and its detection range for fighter-type targets will not exceed 200 kilometres.
The N036B side-view radar has a hexagonal shape, with an antenna length of about 0.5 meters and a width of 0.3 meters. It integrates 358 T/R radar components. Although its visual range is far lower than that of the N036, it can significantly broaden the field of view. Through a pair of radars on both sides, the Su-57’s field of view along the axis can reach ±135°.
There are two N036 L-band phased array radars on the movable leading-edge flaps. Their detection range is equivalent to that of the N036 main fire control radar, and the wider-wavelength L-band has a stronger ability to detect targets than the X-band. However, because of the wide wavelength, the L-band radar has low accuracy and can only provide the approximate coordinates of the target.
N036L can only detect the target’s range and azimuth information as a flap radar but cannot measure the height. In other words, after the N036L radar finds the target, the X-band radar on the nose still needs to search by itself.
The purpose of Su 57’s design of a large number of radars is to spot the opponent’s fifth-generation aircraft first and make up for the disadvantages of its stealth capabilities. This “distributed radar” is in sharp contrast with the mainstream omnidirectional situational awareness mode of the F-22 and F-35 “distributed optoelectronics”.
But the shortcomings of Su-57’s “unusual way” style are also undeniable, which are mainly manifested in the following four aspects:
First, the five radars have significantly increased the difficulty of signal processing. The five radars of the Su-57are separate systems; they are independent.
Although the signals received by each radar must be integrated and summarized by the N036UVS central processing unit, data fusion is still difficult. For example, the side-view radar found and tracked a target, but then the target entered the main fire control radar field of view. At this time, if the information cannot be shared in time or the signal processing is not fast enough, the main fire control radar has to be correct. The same item is repeatedly searched and tracked, and it cannot be quickly locked. It can be seen that the multi-radar design of Su-57 is still very different from China’s KLJ-7A three-dimensional array radar.
The fire control processing capabilities of Russian fighter jets have always been relatively limited, and it is quite challenging to maximize the detection effect of the five radars.
Second, the radar stealth capability of the fifth-generation aircraft is generally stronger than the infrared stealth capability. The detection effect of the Su-57 “distributed radar” is not as good as the F-35 distributed aperture system (DAS).
At present, the radar stealth of the fifth-generation aircraft is mainly aimed at the X-band, and its wave-absorbing paint and sawtooth design are all different. In this case, the X-band radar detection effect of the Su-57 will be greatly reduced. Although the L-band detection effect is relatively good, the accuracy is too poor, and the X-band radar must fuse the information it provides to complete the lock-in attack to be valuable. Still, Russa needs to produce a good computer and software to become a reality for pilots.
Third, Su-57’s “distributed radar” must radiate electromagnetic waves outwards to work, equivalent to a person walking at night with flashlights all over his body, making it easier to be spotted.
The F35’s AN/ASQ239 integrated electronic warfare system can passively detect radio frequency signals up to 482 kilometers, and can accurately locate the enemy’s radio frequency sensors at a distance of 217 kilometers, which is enough to guide anti-radiation missiles to strike.
The ten 4-band conformal antennas of the AN/ASQ-239 system are embedded in the front and rear edges of the F-35 main wing and the rear edge of the tail wing, which can provide 360° omnidirectional full-band signal monitoring and collection functions. That is to say, Su-57, who turned on the radar, had not discovered the F-35, and he was exposed or even locked.
Fourth, the energy consumption, heat dissipation, weight gain, and reliability degradation caused by the five radars are all significant problems. The energy consumption and cooling requirements of the five Su-57 radars are much higher than that of a high-power active phased array radar, and each radar must have its own transmission, reception, processing and cooling system. This will greatly increase complexity, reduce reliability, and weight will remain high. No matter how strong Russia’s system integration capabilities are, it is difficult to solve so many problems that have arisen simultaneously by introducing five radars into one aircraft with coordination of these radars.
In addition, the gallium arsenide components of the active phased array radar used by the Su-57 are still produced in South Korea. Not long ago, the exporter Seoul Semiconductor Corporation of South Korea, under pressure from the United States, has announced that it would stop selling high-performance gallium arsenide semiconductor equipment to Russia.
The export ban will affect the production of the Su-57’s radar and other types of equipment such as Su-35’s radar.
Although the N036 radar manufacturer Tikhomirov Instrument Manufacturing Scientific Research Institute announced in 2019 that the transceiver components of the N036 radar can be produced in Russia, it is not easy to get through the entire industrial chain from raw materials to production lines, especially The problem of high scrap rate is not so easy to solve. There is still a considerable distance between production and mass supply. Russia is yet to manufacture a production variant AESA radar for Su-57 or any other aircraft. Otherwise, Russia will not purchase from South Korea.
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