⏩ Stealth of Chengdu beaten by Sukhoi – Learn how
A Sukhoi Su-30MKI (NATO reporting name Flanker-C) of the Indian Air Force reportedly managed to detect the latest Chinese Chengdu J-20 jet fighter, which is supposed to be a top-of-the-line stealth aircraft operated by the People’s Liberation Army Air Force (PLAAF), reports Indian Defence Research Wing. According to the outlet, when the new Chinese jets were conducting flight training over Tibet, Indian pilots on Russian-made Su-30MKIs managed to detect and track them from Indian airspace.
“The Sukhoi’s radar can see them. The new Chinese jets are not so invisible after all. No special technology is required to detect the J-20, as it can be detected by ordinary radar stations,” Indian Air Force commander Arup Shaha said.
👉How does Su-30MKI detects J-20 Chengdu ?
Stealth aircraft like J-20 Chengdu boast of being able to avoid detection using a variety of stealth technologies that reduce reflection and emission of radar, infrared, visible light, radio frequency spectrum and audio. But stealth is not a cloak of invisibility, rather the technology simply delays detection.
Firstly, if Chengdu would be carrying an external fuel tank or any other device fitted on the ventral side, it would be easily detected. Secondly, any aircraft with empennage surfaces such as two tail wings including F-22, not just Chengdu would not be invisible. Thirdly, Su-30 MKI takes into account the heat, sound and other emissions as well as physical characteristics of the aircraft to locate it.
Essentially, a stealth aircraft must be optimized to defeat higher-frequency bands. The low observable signature of the aircraft will cause a resonance effect once the frequency wavelength exceeds a certain threshold. The Thumb Rule is that this occurs when a feature on the aircraft, such as a tail-fin is less than eight times the size of a particular frequency wavelength. Radar Absorbing paints do the rest.
Now achieving this optimisation of features is tricky business, because you have to keep the aircraft aerodynamically stable as well.
Tactical Air radars that employ low frequency are almost sure to detect stealth fighter jets like F-22, F-35 or Chengdu. Aircrafts like B-2 Spirit which do not employ resonance features do better against these radars. However there is a twist here too. These low-frequency radars do not provide enough detailed coordinates to guide a missile onto target.
Many countries are developing advanced UHF and VHF band early warning radars that use longer wavelengths to cue their radars on a stealth fighter’s approximate approach direction. Though Su-30 MKI already comes with very good BARS radar, but even these could have been further upgraded as was reported in the plans sometime back, which may largely have been kept confidential.
Chengdu J-20, to have reduced radar and thermal detection should satisfy a list of conditions which ultimately will decide the success of the aircraft. These include reduced thermal emission from thrust, altered and optimised physical characteristics of the general configuration (such as minimal radar cross section), decreased detection when the aircraft opens its weapons bay and lesser degree of infra-red and radar detection during adverse weather conditions.
Conclusion : Su-30MKI finally detects Chengdu J-20 due to either or both of these two reasons.
1. Chinese have not been successful in optimising one or more features of Chengdu.
2. Radars of Su-30 MKI have been further enhanced.