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ChengduJ-XX[J-20]StealthFighterPrototype
A Preliminary Assessment

Technical Report APA-TR-2011-0101

Dr Carlo Kopp,SMAIAA, SMIEEE, PEng,
PeterGoon,BE (Mech), FTE (USNTPS)

3^rd January,2011
Updated 11th, 12th, 13th, 15th January, 2011
Updated April, 2012
Text©2011CarloKopp, Peter Goon

First flight of Chengdu J-XX[J-20]prototype, 11th January, 2011 [click to enlarge]. Note the planformalignment and lower fuselage shaping, optimised for all aspect Very LowObservable performance. The nozzles include serrated joins and nozzlerim (Chinese Internet).

Introduction

In lateDecember, 2010, imagery of what is claimed to be China's new stealthfighter has emerged on a range of Chinese Internet sites.

Therehave been no official Chinese disclosures as yet, so many of theclaims about the aircraft appearing in the media may only bespeculation presented as fact.

Theaircraft may be a technology demonstrator or a prototype for a massproduction fighter aircraft. The latter is however much more likely,given that the Deputy Chief of Air Staff PLA-AF Gen. He Weirongclaimed an IOC between 2017 and 2019, in a November, 2009, publicdisclosure^ⁱ.

The following is a preliminary assessment only and subject to revision.APA willproduce a more complete assessment at a future date, once moretechnical material and the detailed analysis of same becomesavailable.

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

TechnicalObservationsonthePrototypeDesign

The J-XX/J-20 is a large fighter, similar in size to anF-111. This first-of-type aircraft presents with a large dihedralcanard-delta wing configuration; with a pair of outward/rearward cantedall moving combined vertical/horizontal tails; and, similarly large,outward canted ventral fins/strakes which, if all moving like the tailsand retained on any production version, will make for some quiteadvanced capability options in the areas of controllability andmanoeuvrability. There is little doubt this configuration is intendedto provide good sustained supersonic cruise performance with a suitableengine type, and good manoeuvre performance in transonic and supersonicregimes.

The stealth shaping is without doubt considerably betterthan 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-35Joint Strike Fighter.

The J-XX/J-20 design appears to be largely built around thestealth shaping design rules employed in the F-22A Raptor:

The chined J-XX/J-20 nose section and canopy are close inappearance to the F-22, yielding similar signature performance in amature design.

The J-XX/J-20 trapezoidal edge aligned engine inlets areclosest to the F-22, though appear to be larger and employ an F-35style DSI (Diverterless Supersonic Inlet) design, obviously intended toimprove on F-22 inlet edge signature.

The J-XX/J-20 wing fuselage join, critical for beam and allaspect stealth, is in shaping and angle very similar to the F-22, andclearly superior to both the Russian T-50 PAK-FA prototypes and theF-35 Joint Strike Fighter.

The J-XX/J-20 flat lower fuselage is optimal for all aspectwideband stealth, and emulates the F-22 design closely.

Planform alignment of the J-XX/J-20 shows exact angularalignment between canard and delta leading edges, and exact crossed(starboard to port, port to starboard) angular edge alignment betweencanard and delta trailing edges. Leading edge sweep is ~43°, clearlyintended for efficient supersonic flight.

The J-XX/J-20 nose and main undercarriage doors employX-band optimised edge serration technology, based on F-117A and F-22design rules.

The aft fuselage, tailbooms, fins/strakes and axi-symmetricnozzles are not compatible with high stealth performance, but may onlybe stop-gap measures to expedite flight testing of a prototype.

The airframe configuration and aft fuselage shape would becompatible with an F-22A style 2D TVC nozzle design, or a non-TVCrectangular nozzle designed for controlled infrared emission patternsand radio-frequency stealth.

The airframe configuration is compatible with ventral andside 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 thefuselage configuration and large internal volume of the big delta wing.This indicates an intent to provide a sustained supersonic cruisecapability, in the manner of the proposed FB-22.

The PLA have not disclosed the engine type. There areclaims that the Russians supplied supercruise capable 117S seriesengines, though, subject to the overall efficiency of the aircraft’saerodynamics, these would likely not be sufficient to extract the fullperformance potential of this advanced airframe.

The intended sensor suite remains unknown. China has yet todemonstrate an AESA radar, or an advanced indigenous Emitter LocatingSystem (ELS). However, these could become available by the time thisairframe enters production. Suitable Russian hardware is currently inlate 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 distancesbetween PLA-AF and PLA-N fixedbasing along the eastern seaboard of mainland China and US airfields atKadena AFB on Okinawa and Andersen AFB on Guam. The J-XX/J-20 is wellsized to hold both of these bases at risk (Kopp, 2005).

Unrefuelledcombat radius performance for a Hi-Hi-Hi profile in a fighter in thesize and weight class of the FB-111A typically falls between 1,000 and1,500 nautical miles, subject to a range of assumptions and engine TSFCduring the profile. This map depicts the geographical coverageachievable from Anshan AB, Dachang AB and Foluo Northeast AB withcombat radii of 1,000 and 1,500 nautical miles respectively. Azimuthalequidistant projection centred on Dachang AB (C. Kopp)^vi.

GeneralConclusions

The sizeof the J-XX/J-20 airframe, and the self evident focus on supersonicpersistence, suggests, at a minimum, an intention to provide a longrange interceptor for anti-access operations in the Second IslandChain geography. It is likely any production design J-XX/J-20 willincorporate an aerial refuelling probe to further extend its largeoperating radius.

Astealthy, supercruising, long range interceptor would provide thePLA-AF with the capability to penetrate an opposing IADS to destroyassets like E-3 AWACS, RC-135V/W Rivet Joint, other ISR systems, andimportantly, Air Force and Navy tankers. This would significantlycomplicate if not close down air operations from Andersen AFB andfixed basing in the Ryukyu chain, Japanese main islands, and Koreanpeninsula, during the opening phase of any contingency.

Navaltask forces structured around CVBGs and operating within the 1,000NMI plus radius of the J-XX/J-20 would be at significant risk ofrapidly losing their E-2C/D AEW&C and EA-18G Growler ElectronicAttack coverage during the opening phase of any contingency.

Anynotion that an F-35 Joint Strike Fighter or F/A-18E/F Super Hornetwill be capable of competing against this Chengdu design in aircombat, let alone penetrate airspace defended by this fighter, wouldbe simply absurd. The F-35 Joint Strike Fighter and F/A-18E/F SuperHornet are both aerodynamically and kinematically quite inferior tothe as presented J-XX/J-20 design, and even the shape based VLOcapability in the J-XX/J-20, as presented, will effectivelyneutralise any sensor advantage either type might possess againstearlier Russian and Chinese fighter designs.

Multi-RoleOptionsandProductionNumbers

TheJ-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, ifequipped with internal guided bombs, such as the Luoyang/CASC LT-3Laser / 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 wingkits modelled on the JDAM-ER. CASC displayed compact 250 lb and 125lb variants of the LS-6 at Zhuhai in 2010, these derivative weaponsbeing direct analogues to the US GBU-39/B Small Diameter Bomb,currently being integrated on the F-22A Raptor^ⁱⁱ.

Amature J-XX/J-20, with a full strike capability, would be a directone-for-one equivalent to the proposed dual role FB-22A, which waschampioned by Dr. James G. Roche during his tenure as SecAF, until2005^ⁱⁱⁱ.

ThePLA-AF has not disclosed as yet intended production quantities. Thestated IOC of the J-XX/J-20 directly aligns with the retirement dateof the second tranche of Su-27SK Flanker B and first tranche ofSu-30MKK Flanker G currently in operational service. It is areasonable conclusion that the J-XX/J-20 is intended as an eventualreplacement for PLA-AF Flanker B/G and later PLA-N shore basedSu-30MK2 Flanker G long range multirole fighters. If the J-XX/J-20 isintended to directly replace PLA Flankers, numbers in the order of400 – 500 aircraft are credible.

TheStrategicImpact of China's J-XX [J-20] Stealth Fighter

What China's NewStealth FighterMeans for the F-35 JSF and F/A-18E/F Super Hornet

Endnotes/References

iL.C.RussellHsiao,CHINA’S FIFTH-GENERATION FIGHTERS AND THE CHANGINGSTRATEGIC BALANCE, CHINA BRIEF, VOLUMEIX, ISSUE 23, NOVEMBER 19, 2009, Jamestown Foundation,
URI: .

iiKoppC.,PLAGuided Bombs, Technical Report APA-TR-2009-0808, Air PowerAustralia, URI: .

iiiChristopherBolkcom, Air Force FB-22 Bomber Concept, PDF-A/RS21848, March 21,2005, Congressional Research Service, URI:

iv Bill Sweetman, China'sStealth Striker,Defence Technology International, 27thDecember, 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

vBillSweetman, J-20 - Denial Is Not An Option,Defence TechnologyInternational, 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'sLiberationArmy Air Force and Naval Air Arm Air Base Infrastructure,TechnicalReportAPA-TR-2007-0103,URI:
http://www.ausairpower.net/APA-PLA-AFBs.html

vii Kopp C.,Guam-TipoftheSpear, Defence Today, March 2009, URI:http://www.ausairpower.net/SP/DT-Guam-March-2009.pdf

viiiMillsC.L.,What China's New J-20 Stealth Fighter Means for theF-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

ixKoppC.,MiG'sI.42/44MFI-AFirstLook,AustralianAviation, March,1998, URI:http://www.ausairpower.net/Analysis-MiG-MFI.html.

xKoppC. and Goon P.A., Assessing the Sukhoi PAK-FA,APA Analyses,Vol. VII APA-2010-01, February, 2010, URI:.