from Chengdu-Huangtianba air eld has
almost dried up.
The current status of both the J-10 and
J-20 programs is ultimately unknown
— there are no details of aircraft built in
recent months, nor numbers delivered.
In the meantime, it seems as if China’s
still-active community of ‘spotters’ has
found a way to circumvent the ban on
publishing photos. New developments
are no longer posted as photographs
but as sketches or ‘comic strips’. The
rst examples of these generally fairly
detailed drawings showed the WS-10B-
powered J-20A prototypes, serials ‘2021’
and ‘2022’, long before the rst photos
appeared. The TVC J-10B testbed was
depicted several times. Most recently,
these sketches revealed a new J-20
prototype tted with a long pitot boom
similar to the J-10B and yellow/black
calibration markings.
Finally, on April 6, an artist posted a
‘cartoon’ on his Weibo account — the
Chinese equivalent of Twitter. This
depicted a ‘conversation’ between the
J-10B and this J-20 testbed. The J-10B
welcomes the J-20A with, ‘Hey brother,
the new engine has been tested for you; it
feels powerful’. To which the J-20 replies:
‘Oh, nice! But let me install one rst.’
Reportedly, the J-20A completed its
maiden ight with the new engine one
day earlier.
If all these reports are correct, then
Chengdu is currently testing not only two
di erent variants of the WS-10 engine —
one tted with a ‘simple’ stealth nozzle
with serrated feathers and one tted
with a TVC nozzle — but these engines
have been tted to two di erent aircraft
types. All in all, this may be evidence that
China’s troubled ghter engine program
is now on its way to full
independence.prominent saw-tooth edges. Although
super cially similar to the nozzles
used by other low-observable aircraft
to improve their rear-aspect stealth
characteristics, these ‘petals’ are not of
a single-piece design but feature an
unusual double-feathered mechanism.
The TVC design di ers from the
technology used in the Su-35 and its
NPO/Saturn izdeliye 117S turbofan,
in which the whole base of the nozzle
rotates to control direction. The J-10B
system is more akin to that tested in
the F-16 VISTA, where the exhaust is
vectored using paddles. It also shares
some remarkable similarities with Salyut’s
AL-31FU concept that was tested on
a Su-27. Given the close co-operation
between the Russian Salyut factory and
Chengdu, this might hint at a possible
closer relationship.
There have been rumors that Chengdu
showed great interest in Salyut’s TVC
technology and that company personnel
made frequent visits to Salyut for
consultations before Shenyang Liming
began building the engine. Salyut
provides the AL-31FN used by the
J-10B/C and J-20. Whatever the truth, it
seems the chosen design could provide
a greater range of nozzle geometry
and increased de ection angle. It may
also provide better control over the
convergent/divergent functions of thenozzle at di erent de ection angles and
might even result in reduced thrust loss.
Otherwise, the TVC J-10B — which is
externally similar to a late-production
J-10C — features a redesigned vertical tail
n base with part of the bottom of the
brake chute housing removed. This is likely
to allow the TVC nozzle to rotate upwards
without damaging the tail. Final features
are mounting points for an additional,
larger brake ‘chute related to spin testing
— this has already been seen on other
J-10 prototypes but is not yet installed.
Based on latest reports, the TVC testbed
is based on the modi ed fourth J-10B
prototype, serial ‘1034’.
Despite this apparent breakthrough, the
author doesn’t expect production J-10s to
feature TVC any time soon. Most likely, the
results of these tests will inform the J-20A
program and help develop a nozzle for the
de nitive WS-15, currently in development
for Chengdu’s ‘ fth-generation’ ghter.J-20 and TVC
It’s possible that Chengdu allowed the
image of the TVC J-10B to leak as a way of
con rming that a J-20 is now ying with
thrust-vectoring engines. A single J-20
prototype allegedly began ying with the
same TVC version of the WS-10B in early
April. Regrettably, for around a year now,
much stricter internet security rules mean
that the previous ow of news and imagesAbove: A grainy
image of the
TVC-equipped
J-10B shows a
few important
modifi cations.
The exhaust
nozzle is not
thought to
feature a single-
piece design
but instead
an unusual
double-feathered
mechanism.
Below: A J-10
fi tted with the
standard WS-10
engine.EYE ON THE EAST // CHINESE THRUST-VECTORING
26 July 2018 //^ http://www.combataircraft.net
EYE ON THE EAST //
25-27 Eye on the East C.indd 26 20/05/2018 11:34