Chengdu J-XX [J-20] Stealth Fighter Prototype

Chengdu J-XX [J-20] Stealth Fighter Prototype A Preliminary Assessment Technical Report APA-TR-2011-0101

by Dr Carlo Kopp, SMAIAA, SMIEEE, PEng, Peter Goon, BE (Mech), FTE (USNTPS) 3rd January, 2011 Text © 2011 Carlo Kopp, Peter Goon

Elevated head on view of Chengdu prototype, December, 2010 (Chinese Internet).

Introduction Technical Observations on the Prototype Design General Conclusions Multi-Role Options and Production Numbers Endnotes/References: Prototype Imagery and Multimedia

Introduction In late December, 2010, imagery of what is claimed to be China's new stealth fighter has emerged on a range of Chinese Internet sites. There have been no official Chinese disclosures as yet, so many of the claims about the aircraft appearing in the media may only be speculation presented as fact. The aircraft may be a technology demonstrator or a prototype for a mass production fighter aircraft. The latter is however much more likely, given that the Deputy Chief of Air Staff PLA-AF Gen. He Weirong claimed an IOC between 2017 and 2019, in a November, 2009, public disclosurei. The following is a preliminary assessment only and subject to revision. APA will produce a more complete assessment at a future date, once more technical material and the detailed analysis of same becomes available.

Technical Observations on the Prototype Design The J-XX/J-20 is a large fighter, similar in size to an F-111. This first-of-type aircraft presents with a large dihedral canard-delta wing configuration; with a pair of outward/rearward canted all moving combined vertical/horizontal tails; and, similarly large, outward canted ventral fins/strakes which, if all moving like the tails and retained on any production version, will make for some quite advanced capability options in the areas of controllability and manoeuvrability. There is little doubt this configuration is intended to provide good sustained supersonic cruise performance with a suitable engine type, and good manoeuvre performance in transonic and supersonic regimes. The stealth shaping is without doubt considerably better than that seen in the Russian T-50 PAK-FA prototypes and, even more so, than that seen in the intended production configuration of the F-35 Joint Strike Fighter. The J-XX/J-20 design appears to be largely built around the stealth shaping design rules employed in the F-22A Raptor: The chined J-XX/J-20 nose section and canopy are close in appearance to the F-22, yielding similar signature performance in a mature design. The J-XX/J-20 trapezoidal edge aligned engine inlets are closest to the F-22, though appear to be larger and employ an F-35 style DSI (Diverterless Supersonic Inlet) design, obviously intended to improve on F-22 inlet edge signature. The J-XX/J-20 wing fuselage join, critical for beam and all aspect stealth, is in shaping and angle very similar to the F-22, and clearly superior to both the Russian T-50 PAK-FA prototypes and the F-35 Joint Strike Fighter. The J-XX/J-20 flat lower fuselage is optimal for all aspect wideband stealth, and emulates the F-22 design closely. Planform alignment of the J-XX/J-20 is impossible to fully assess until in-flight imagery becomes available. The J-XX/J-20 nose and main undercarriage doors employ X-band optimised edge serration technology, based on F-117A and F-22 design rules. The aft fuselage, tailbooms, fins/strakes and axi-symmetric nozzles are not compatible with high stealth performance, but may only be stop-gap measures to expedite flight testing of a prototype. The airframe configuration and aft fuselage shape would be compatible with an F-22A style 2D TVC nozzle design, or a non-TVC rectangular nozzle designed for controlled infrared emission patterns and radio-frequency stealth. The airframe configuration is compatible with ventral and side opening internal weapon bays, and large enough to match or exceed, by some degree, the internal weapons payload of the F-22A Raptor. Internal fuel fraction is also likely to be high, given the fuselage configuration and large internal volume of the big delta wing. This indicates an intent to provide a sustained supersonic cruise capability, in the manner of the proposed FB-22. The PLA have not disclosed the engine type. There are claims that the Russians supplied supercruise capable 117S series engines, though, subject to the overall efficiency of the aircraft’s aerodynamics, these would likely not be sufficient to extract the full performance potential of this advanced airframe. The intended sensor suite remains unknown. China has yet to demonstrate an AESA radar, or an advanced indigenous Emitter Locating System (ELS). However, these could become available by the time this airframe enters production. Suitable Russian hardware is currently in late development and/or test.

The J-XX/J-20 is a large fighter, similar in size to an F-111 (Chinese Internet). (US DoD)

Above, below: Histograms of distances between PLA-AF and PLA-N fixed basing along the eastern seaboard of mainland China and US airfields at Kadena AFB on Okinawa and Andersen AFB on Guam. The J-XX/J-20 is well sized to hold both of these bases at risk (Kopp, 2005).

General Conclusions The size of the J-XX/J-20 airframe, and the self evident focus on supersonic persistence, suggests, at a minimum, an intention to provide a long range interceptor for anti-access operations in the Second Island Chain geography. It is likely any production design J-XX/J-20 will incorporate an aerial refuelling probe to further extend its large operating radius. A stealthy, supercruising, long range interceptor would provide the PLA-AF with the capability to penetrate an opposing IADS to destroy assets like E-3 AWACS, RC-135V/W Rivet Joint, other ISR systems, and importantly, Air Force and Navy tankers. This would significantly complicate if not close down air operations from Andersen AFB and fixed basing in the Ryukyu chain, Japanese main islands, and Korean peninsula, during the opening phase of any contingency. Naval task forces structured around CVBGs and operating within the 1,000 NMI plus radius of the J-XX/J-20 would be at significant risk of rapidly losing their E-2C/D AEW&C and EA-18G Growler Electronic Attack coverage during the opening phase of any contingency. Any notion that an F-35 Joint Strike Fighter or F/A-18E/F Super Hornet will be capable of competing against this Chengdu design in air combat, let alone penetrate airspace defended by this fighter, would be simply absurd. The F-35 Joint Strike Fighter and F/A-18E/F Super Hornet are both aerodynamically and kinematically quite inferior to the as presented J-XX/J-20 design, and even the shape based VLO capability in the J-XX/J-20, as presented, will effectively neutralise any sensor advantage either type might possess against earlier Russian and Chinese fighter designs.

Multi-Role Options and Production Numbers The J-XX/J-20 design could be employed as a penetrating strike aircraft, in the combat radius class of the F-111 or Su-34 Fullback, if equipped with internal guided bombs, such as the Luoyang/CASC LT-3 Laser / Satellite Aided Inertially Guided Bomb, the FT-1, FT-2, FT-3, FT-4, FT-5 and LS-6 series Satellite Aided Inertially Guided Bombs. These are Chinese analogues to the US JDAM, some including glide wing kits modelled on the JDAM-ER. CASC displayed compact 250 lb and 125 lb variants of the LS-6 at Zhuhai in 2010, these derivative weapons being direct analogues to the US GBU-39/B Small Diameter Bomb, currently being integrated on the F-22A Raptorii. A mature J-XX/J-20, with a full strike capability, would be a direct one-for-one equivalent to the proposed dual role FB-22A, which was championed by Dr. James G. Roche during his tenure as SecAF, until 2005iii. The PLA-AF has not disclosed as yet intended production quantities. The stated IOC of the J-XX/J-20 directly aligns with the retirement date of the second tranche of Su-27SK Flanker B and first tranche of Su-30MKK Flanker G currently in operational service. It is a reasonable conclusion that the J-XX/J-20 is intended as an eventual replacement for PLA-AF Flanker B/G and later PLA-N shore based Su-30MK2 Flanker G long range multirole fighters. If the J-XX/J-20 is intended to directly replace PLA Flankers, numbers in the order of 400 – 500 aircraft are credible. APA NOTAM: What China's New Stealth Fighter Means for the F-35 JSF and F/A-18E/F Super Hornet CASC displayed compact 250 lb and 125 lb variants of the LS-6 at Zhuhai in 2010, these derivative weapons being direct analogues to the US GBU-39/B Small Diameter Bomb (© 2011 Air Power Australia).

Endnotes/References: i L.C. Russell Hsiao, CHINA’S FIFTH-GENERATION FIGHTERS AND THE CHANGING STRATEGIC BALANCE, CHINA BRIEF, VOLUME IX, ISSUE 23, NOVEMBER 19, 2009, Jamestown Foundation, URI:http://www.jamestown.org/uploads/media/cb_009_64.pdf. ii Kopp C., PLA Guided Bombs, Technical Report APA-TR-2009-0808, Air Power Australia, URI:http://www.ausairpower.net/APA-PLA-GBU.html. iii Christopher Bolkcom, Air Force FB-22 Bomber Concept, RS21848, March 21, 2005, Congressional Research Service, URI: http://www.fas.org/sgp/crs/weapons/RS21848.pdf iv Bill Sweetman, China's Stealth Striker, Defence Technology International, 27th December, 2010, URI: http://www.aviationweek.com/aw/blogs/defense/index.jsp?plckController=Blog&plckBlogPage=BlogViewPost&newspaperUserId=27ec4a53-dcc8-42d0-bd3a-01329aef79a7&plckPostId=Blog%3a27ec4a53-dcc8-42d0-bd3a-01329aef79a7Post%3acaf36660-d425-4fbc-a284-008017b2b444&plckScript=blogScript&plckElementId=blogDest v Bill Sweetman, J-20 - Denial Is Not An Option, Defence Technology International, 28th December, 2010, URI: http://www.aviationweek.com/aw/blogs/defense/index.jsp?plckController=Blog&plckBlogPage=BlogViewPost&newspaperUserId=27ec4a53-dcc8-42d0-bd3a-01329aef79a7&plckPostId=Blog%3a27ec4a53-dcc8-42d0-bd3a-01329aef79a7Post%3a1a18ec63-5bf5-471c-9997-9f0bd783d131&plckScript=blogScript&plckElementId=blogDest vi Kopp C., People's Liberation Army Air Force and Naval Air Arm Air Base Infrastructure, Technical Report APA-TR-2007-0103, URI: http://www.ausairpower.net/APA-PLA-AFBs.html vii Kopp C., Guam - Tip of the Spear, Defence Today, March 2009, URI: http://www.ausairpower.net/DT-Guam-March-2009.pdf viii Mills C.L., What China's New J-20 Stealth Fighter Means for the F-35 JSF and F/A-18E/F Super Hornet, APA NOTAM #69, 31/12/2010, URI: http://www.ausairpower.net/APA-NOTAM-311210-1.html

Prototype Imagery and Multimedia

(All imagery via Chinese Internet)

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