Arjun Subramanian P
The initiation of the programme in the late 1990s to develop a stealth fighter was a very bold attempt by the Chinese aeronautical complex given that it was a just a decade after the initiation of the military modernisation programme. The Chinese aeronautical industry was not very mature at that time. However, China picked up quickly and the phase of advancement of its aerospace industries have been astonishing. A very strong government backing in addition to the heavy financing of the development projects is the recent behind the success.
Assisted by the Chinese government in every way from acquiring dual use technology, military industrial espionage and bringing in the overseas Chinese talent pool, the Chinese aviation industries managed a rapid progress. The development of the aviation industry was a systematically planned endeavour by the Chinese leadership. Those efforts has now culminated into making China the second country to indigenously develop and induct a stealth fighter aircraft.
The People’s Liberation Army Air Force (PLAAF) has inducted the J-20A stealth fighter into active service and the platform has reportedly gone into initial low rate production. Reportedly three fighters were inducted into service. With this China becomes the second nation after United Stated to indigenously develop a stealth fighter aircraft and operationalize it. The aircraft made its first appearance in 2011 and had since remained in news as multiple prototypes were built during its development phase. The aircraft made its last public appearance in the Zhuhai air show in November 2016. The aircraft is believed to be built on stolen stealth technology from the west. The development timeframe of the aircraft can be said to be extremely short going by the complexity of technology involved.
The J-20 is supposed to be the rival to the US built F-22A Raptor. It however has a number of shortfalls at present in terms of matching up to the US stealth aircraft. While the US stealth fighter is a true fifth generation fighter, the J-20A is not. Further, the F-22A is a designated air superiority fighter, but the actual role of the J-20 is not yet known. However, the development cycle of the J-20 was relatively fast probably due to the availability of the technical knowhow of stealth design obtained through clandestine means added up by massive indigenous efforts. Open source data suggest that the aircraft was in development since the late nineties.
The process of development can be said to be incremental through numerous refinement to the various features of the aircraft. Some of the improvements to the avionics were the direct result of the technological advancement made in the field of aviation electronics, airframe and indigenous radar development. In its development timeframe, a total of eight prototypes were built, with each incorporated with improved electronics, design and refinement in RCS reduction over the previous prototype.
The first prototype coded ‘2001’ made its maiden flight in January 2011 and continued to conduct multiple test flights. The second prototype coded the ‘2002’, which was later repainted as the 2004, was revealed in mid-2012 which was speculated to contain a different and possibly advanced radar based on relocation of the pitot tube. The third prototype (code ‘2011’) that was revealed in early 2014 were given a number of significant improvements over the previous 2002 model. The notable changes were a completely redesigned nose and air intake section, new dielectric panels in the front fuselage, redesigning of the landing gear section, modified tail/rudders and a shortened exhaust section. All these redesigns were done to reduce the radar cross section. The redesign of the air intake was a major attempt at reducing RCS.
A significant improvement to the sensor package was the addition of the Electro Optical targeting System (EOTS) attached below the nose. The fourth prototype (code ‘2012’) was also spotted later in the same year, however, no externally visible modification was observed and was believed to be for speeding up the testing and trials by using two machines of the same version. Towards the end of the year two more prototypes were revealed with the code ‘2013’ and ‘2015’ in the month of November and December respectively. The important addition that was noticed on the sixth prototype coded 2015 was the enlarged tail boom speculated to be hosting a rear radar for 360 degree coverage for better situational awareness.
By September 2015 the seventh prototype marked ‘2016’ was rolled out. There were further changes to reduce RCS. The divertless supersonic inlet (DSI) was enlarged to reduce the radar waves that would be reflected off the engine intake area. The change in the DSI also gave way to speculations on the use of an improved engine with higher thrust. In this variant, significant attempts to improve stealth at the aft section can be noticed. The entire engine body was completely tucked inside the fuselage and serrated nozzle was noticed. The shape of the trapezoidal boom at the rear was changed to reduce aft RCS or for the use of a new ECM or radar equipment. This prototype was the pre-production version.
The last and the eighth prototype was rolled out in the end of 2015 and was the version close to the production version. The major externally visible improvement was the redesigning of the canopy enabling better rear view for the pilot. The roll out function was marked with unusual celebration which indicated that this version would go for the initial low rate production after testing. And as expected several of this design was produced with airframe markings ‘2101’-‘2104’ throughout 2016. All these prototypes were sent to the China Flight Test Establishment (CFTE) for testing.
Speculations on the J-20 entering service started by the end of 2016 itself. However, only in March 2017 the state run CCTV announced the induction of the aircraft into PLAAF but added that the machine had not yet entered serial production as there were a series of problems yet to be addressed like control systems, stealth coatings, hull materials, infrared sensor as well as the indigenous engine. In September this year, China’s military spokesperson confirmed that the aircraft has officially entered service. However, it is not known if all the problems stated earlier that year had been resolved.
The aircraft was primarily being tested with a Russian AL-31 engine though at times few photographs of the J-20 showed it with the indigenous Chinese WS-10 power plant. Though China has made key advancement in indigenous engine design and development like manufacturing and production line standardisation, single crystal blade with high melting point powder metallurgy rhenium-nickel super alloy, it is still struggling to bring out a reliable aero engine. Nevertheless, overtime, the Shenyang-Liming has managed to improve and fine tune its WS-10 Taihang engines.
Very recently image of the latest design variant of the aircraft circulating on the internet was found to be equipped with an improved WS-10 turbofan engine. The engine, according to some analysts appears to have thrust vectoring capability. Further, the nozzle petals were observed to be pointed like the F-35’s F-135 turbofan engine which would reduce the RCS at the nozzle end. Despite this, the initial production variants will be powered by the Russian AL-31FN engine forcing China to depend on Russia for power plants until the indigenous engines are available.
China is also said to have purchased 24 Su-35 fighters for $2 billion most probably to harvest its engine technology which could be used to address the problems with the Taihang engine. The Su-35’s Al-41F1S (117S) engines delivers far greater thrust and it has thrust vectoring capability. The recent testing of the J-20 with a modified WS-10 engine might have been the result of the detailed studying of the Su-35’s engine as Russia has already delivered a couple of Su-35s’ as per the purchase contract.
Certain reports also mention that the actual engines to power the J-20 are the WS-15 with an intended 180KN thrust capability. The WS-15, as claimed, is being designed with super cruise capability. However, the exact status of the power plant is not known at present. With super cruise and thrust vectoring, the stealth fighter will have significant edge in within Visual Range air-to-air combat and longer combat radius.
The J-20 now having entered service, will be evaluated by the PLAAF and a new training regimen will also be formulated to train combat pilots to man the aircraft. Transition to the aircraft will be mostly from top slot of the fighter jocks who currently fly either the J-11B or the J-10 fighters. However, what is still a speculation is the role of the aircraft. Is it primarily an air superiority fighter or a ground attack aircraft? Perhaps looking at the characteristic of the fighter in its current form might throw some light.
The fighter in the current configuration
The aircraft has excellent frontal aspect stealth compared to the aft section. But over its development phase, some attention was also given to the aft section stealth by way of modifying the radar reflective indexes of surfaces near and around the engine exhaust area. Most of the rivet joints have been given saw-tooth shape to reduce fuselage RCS. Radar absorbent paint coating covers the entire aircraft and the canopy has also been given radar deflecting coating. The stealth aspect of the fighter has been improved a lot compared to its initial variant, though not much information is available on the avionics and sensor suit of the aircraft. However, the external modification of the nose section observed over the years leads to an understanding that the aircraft might have been equipped with an AESA radar.
There is also the clear presence of an electro optical targeting system. Various apertures around the aircraft indicate the presence of a distributed aperture system to enable better situational awareness for the pilot. The aircraft, in comparison to the F-22A, is larger in size and will be able to carry more fuel giving it longer range. The aircraft is found to contain four adaptors in its main internal weapons bay and hence can carry four BVR air-to-air missiles or two ground attack bombs. In addition the two side bay can hold a short range air-to-air missiles each.
With the longer range and supersonic capability the aircraft could be used as a long range interceptor. With very low RCS, the fighter is likely to have an edge at first look and first shoot in BVR combat. However, in close air combat the fighter might be at a serious disadvantage as its aerodynamics and lower engine thrust might put it down in a high G turning fight. At present, the J-20 does not sport an engine capable of thrust vectoring which is another drawback in WVR combat.
Even in a non-visual close combat, the opposing aircraft’s IRST might easily pick the J-20 as there appears to be very little attempt at IR signature reduction particularly at the engine exhaust. Hence, the J-20’s key air combat philosophy might be BVR combat. Particularly, it might prove to be exceptionally good in a coordinated combat sweep supported by an AWACS aircraft against fourth generation fighters.
With an excellent frontal stealth aspect much like the F-35, the J-20 could be the right choice to kick the door open in any conflict. The aircraft might be used to good effect to take out the highly dangerous ground based air defence targets and other high value targets. With the horizontal canards at the front, the J-20 would possibly have good flight stability and ease of handling at low altitudes. Against lethal air defence units the aircraft would have to take out the target in the first pass as it could be engaged by the SAM due to the not so efficient aft RCS.
As evident from the images of the aircraft and as mentioned above, some attention has been devoted by the developers to reduce aft section RCS. This might have been done with an intention of enabling the aircraft for ground attacks. However, the unsuppressed IR signature might make it vulnerable to optical sensors and IR homing missiles. The aircraft, as estimated by analysts can carry a few CM-506KG PGMs in its main internal weapons bay. Given its stealth and flight characteristics, though it can perform ground attack, it might primarily be used as an air superiority fighter most likely in combination with AWACS support. Ground attack may be resorted in case of precision bombing of high value or air defence targets.
The J-20 is obviously a big leap for the PLAAF as it gives it, at least in the near future, immense edge in air combat over its neighbours. But all of China’s powerful neighbours are already in the stealth race with the Russians not too far away in fielding their aircraft with a far superior engine in comparison with the J-20. India is also working on its stealth fighter in collaboration with Russia, yet by all likelihood might end up buying the Russian designed single seat stealth fighter. Japan is quite far compared to the others in the region in fielding one, but it is a known fact that the US has already deployed their F-22’s in the Okinawa airbase. Yet considering the cost factor and its indigenous capability, China might field higher number of stealth fighters and maintain an edge in the number game. In the near future, PLAAF most likely would order limited number of J-20A’s in favour a future improved variant of the fighter which can be expected to fill the majority of the stealth regiments.