- The J-20 -
The J-20 (K/JJ20?) #2001 prototype/technology demonstrator made its maiden flight on January 11, 2011 over the city of Chengdu, wearing a distinctive dark green color scheme (RAM coating applied?) and powered by two indigenous WS-1X turbofan engines. The prototype features a pair of all-moving tailfins and Russian 1.44 style twin ventral stabilizing fins and tail booms, which shield the engine nozzles but might increase RCS. Also there are four large underwing actuator fairings which might not be stealth optimized. It also features an F-22 style forward fuselage, including adjustable Caret inlets but with DSI bumps installed at the upper inner corners, as well as a one-piece frameless canopy. Small LERX are installed between the canards and main wings in order to generate vortex together with the canards at high AoA. Two small dark diamond shaped windows can be seen on both sides of the nose, which could house certain EO sensors, such as MAWS and/or IRST. Two additional windows are seen underneath the rear fuselage, plus two more on top of the forward fuselage above the canard wings, suggesting a distributed situational awareness system similar to the EODAS onboard American F-35 was installed providing a full 360° coverage. Besides a large belly weapon bay for short/long-range AAMs (up to 6 PL-10, PL-12C/D & PL-21), two smaller lateral weapon bays have been identified behind the air inlets for short-range AAMs (up to 2 PL-10). The 2001 prototype appears to fly without an internal gun, which is expected to be installed on later ones. First disclosed by US Office of Naval Intelligence (ONI) in 1997 as XXJ, J-20 (Project 718) is a 4th generation heavy air superiority fighter to enter the service with PLAAF between 2016 and 2018, a timeframe much faster than the one (>2020) anticipated by the western military analysts. Since early 90s both CAC/611 Institute and SAC/601 Institute had been working their own designs to bid for a twin-engine heavy fighter with stealth capability and maneuverability comparable to American F-22. It was speculated that 601 Institute was working on a "tri-plane" design (J-18?) based on canard/conventional layout/V-shape tailfin while 611 Institute working on a design based on canard/tailless delta wing/V-shape tailfin/lateral DSI/bump inlet layout. All designs were expected to feature a belly internal weapon bay to reduce RCS, which has been speculated to be <0.05m2 (head-on). J-20 also incorporates an advanced FBW (or FBL?) system fully integrated with the fire-control and the engine systems. Its fire-control radar is expected to be AESA (Type 1475/KLJ5?) based on the less powerful model being tested onboard J-10B, both are developed by the 14th Institute. The radar is thought to be comparable to American APG-77. The next generation secure datalink is believed to be installed as well which provides secure networking with other J-20s and KJ-200/2000 AWACS. The aircraft also features a "pure" glass cockpit (two large color LCDs plus a few smaller ones and a wide-angle holographic HUD). Many of these subsystems have been tested onboard J-10B to speed up the development (see above). A dorsal receptacle might be installed to reduce RCS instead of a nose probe for IFR purpose. The exact type of engine powering prototypes is uncertain, even though a Chinese or Russian turbofan engine including AL-31F (13t class) and enhanced WS-10 (WS-10X?) (14t class) has been speculated. The enhanced WS-10X turbofan is capable of generating a higher thrust by sacrificing the engine life. Therefore this particular type of engine is for the J-20 prototype only and not for production models. Leaked images suggest that two types of engines were installed (separately on two 2001 prototypes?) but only one type was used for the maiden flight. One is AL-31F, the other is thought to be WS-10X featuring a silver color "stealth" nozzle with saw tooth edges to reduce RCS and IR emission. However the nozzle has yet to demonstrate an axisymmetric TVC capability. It was reported in November 2006 that a 17-18t class T/W=9.5-10 turbofan (WS-15/"large thrust") with a TVC nozzle is being developed and will eventually power J-20s in production. J-20 appears slightly longer and slimmer than both F-22 and T-50, suggesting a compromise between achieving high speed/maneuverability and the less powerful engines available. Therefore currently the J-20 prototype still lacks the supercurise capability until the planned WS-15 turbofan enters the service. Russian assistance was also speculated in terms of software support for calculating the RCS and aerodynamics of various designs. The overall performance of J-20 is thought to be superior to that of Russian T-50 (maneuverability & supercruise) but still inferior to that of American F-22 (electronics & stealth). In August 2008 it was reported that 611 Institute was selected to be the main contractor for the development of J-20 and 601 Institute as the sub-contractor. Subsequently a full-scale metal mockup was built at CAC. One rumor in May 2010 claimed that 611 Institute started to construct the first prototype, which was expected to fly by the end of 2010, even though the full configuration version won't fly until a few years later. Two prototypes have been constructed and the first low-speed taxi trial by 2001 took place on November 4, 2010. Once entering the service, J-20 could pose a significant impact/challenge to the air balance in eastern Asian and western Pacific region.
