Combat aircraft

sensors have been installed. The latest

aircraft display two flush hexagonal-

shaped side fuel/air heat exchangers in

order to reduce RCS. Noticeable too are

two small diamond-shaped windows on

both sides of the nose, which allegedly

house certain electro-optical sensors.

To provide full 360° coverage these are

complemented by two additional sensors

underneath the rear fuselage, as well

as two more located forward and aft of

the cockpit, suggesting a distributed

situational awareness system similar to

the electro-optical distributed aperture

system (EODAS) fitted to the F-35.

Structure-wise, by overall weight the

airframe consists of 20 per cent titanium

or titanium alloys and 29 per cent

composite materials.

Not much is known about the other

systems. The new Type 1475 (KLJ-5) fire

control radar is expected to be an AESA

type under development at the 14th

Institute. The radar is under test on board

a heavily modified Tu-204C airliner acting

as a dedicated radar testbed at the CFTE.

This features the J-20’s front section and

radome as well as several other electronic

warfare and communication systems

in a huge wing-like structure mounted

atop the airliner’s fuselage. A similarly

converted Y-8C assists the testing of

other sub-systems. Reportedly, the

modified J-20A demonstrator ‘2004’ and

the prototypes ‘2013’, ‘2015’ and ‘2016’ are

already equipped with the radar.

Complementing the main radar, the

J-20A has — probably two — additional

side-looking arrays installed underneath

the elongated hexagonal dielectric

fairings on each side of the nose, which

provide improved situational awareness

and extended missile guidance during

a dogfight. Otherwise, the final two

prototypes — ‘2016’ and ‘2017’ — differ

in certain details and represent the final

standard prior to LRIP. Their engines

no longer have the previously typical

silver-metallic sheen and the nozzles now

appear a dark dull charcoal color. The side

weapons bays also seem to be different.

For the record, both ‘2013 and ‘2015’

were transferred to the CFTE at Xi’an-

Yanliang in April 2015, perhaps allowing

the start of weapons tests at the FTTC at

Dingxin. This occurred just prior to the

appearance of the final two aircraft. It is

still not known whether the J-20 has a

gun. There has been much speculation

that an unknown compartment

underneath a panel on the port side of

the fuselage next to the canard wing was

reserved for an internal cannon. This has

not been confirmed, and it seems as if the

LRIP model, at least, has no gun fitted.

Engine mystery

The biggest question surrounding

the J-20 remains its engine. It still

seems as though the definitive WS-15

‘Emei’ is lagging behind the fighter’s

schedule. Based on the most reliable

reports it won’t appear until 2022-24.

Consequently, much has been written

about the issue, and the exact type of

engine used in the aircraft long remained

unclear. There were various rumors —

especially during the early days — of a

redesigned intake, re-profiled vertical

stabilizers and smaller underwing

actuators to further reduce the radar

cross-section (RCS). They also have two

enlarged tail booms — which were

reshaped from ‘2013’ onwards — that

house additional electronic warfare

and self-defense systems, including

two pairs of chaff and flare launchers

to protect the rear hemisphere. Further

modifications include a reshaped canopy

— re-profiled once again with ‘2017’

— featuring an additional inner frame

as well as an electro-optical targeting

system (EOTS) similar to that used by the

F-35, and a retractable in-flight refueling

probe concealed behind a cover on the

starboard side of the cockpit.

The cockpit is a modern ‘glass’ type with

either three large color LCDs or even a

large 24 x 9in touch-screen panoramic

cockpit display (PCD) allegedly controlled

by voice command, like that of the

F-35. There is a smaller LCD between

the pilot’s legs and a prominent wide-

angle holographic head-up display. It is

unknown whether a helmet-mounted

display (HMD) is already operational.

The J-20 is controlled by a sidestick

and throttle. The combination of active

electronically scanned array (AESA) radar,

infra-red search and track, advanced

cockpit design and the potential HMD

further improves the pilot’s situational

awareness by providing the highest

degree of ‘information fusion’.

Externally, the J-20 has a very smooth

surface without any protruding pitot

tubes or inlets, suggesting flush air-data

Below: J-20s

‘2013’ and

‘2015’ together

in a photo that

appeared in

May 2015. From

‘2013’ onwards

the enlarged

tail booms

were subject

to redesign.

These booms

contain self-

defense systems

including

chaff and flare

launchers.

J-20 | FIGHTER FOCUS

55

January 2018 http://www.combataircraft.net

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