The maiden test flight in January of
China's J-20 stealth fighter prototype is an
important strategic milestone in several different
respects, and is part of an ongoing effort by
China to develop advanced military technology.
The J-20 is the first combat aircraft
developed by China that qualifies as
"state-of-the-art" by Western measures. It also
shows that China has mastered "stealth shaping"
technology - the essential prerequisite for
developing stealth aircraft. Finally it shows that
China has managed to integrate its strategic
planning with the functional definition of a
modern combat aircraft. Once fully developed, the
J-20 has the potential to alter the regional
balance in the Asian air power strategic game, by rendering
nearly all regional air
defense systems ineffective.
The People's
Liberation Army (PLA) has yet to disclose any of
the intended performance parameters of this
fighter aircraft, or its intended avionic systems
and weapons fit. As a result, analysts are left
with one choice only, which is to apply analytical
criteria such as size, shape and configuration to
draw an estimate of the aircraft's
characteristics. If applied with rigor, this
technique can produce highly accurate results.
Scaling the dimensions of the J-20 against
proximate ground vehicles of known types in
photographs does yield very accurate dimensions,
showing that the J-20 is a large fighter, in the
size class of the United States F/FB-111 family of
aircraft, or the proposed but never built FB-22A
"theater bomber".
This in turn indicates
an empty weight in the 40,000-50,000 lb class,
depending on construction technique used in the
design, and an internal fuel load of up to 35,000
lb. Inevitably, this yields subsonic combat radius
figures in the 1,000-1,500 nautical mile class,
subject to the thrust specific fuel consumption of
the production engine in subsonic cruise. The J-20
is therefore a fighter built for reach, and would
be competitive in range performance against the
F/FB-111 series, the F-15E Strike Eagle series,
and the new Russian Su-35S Flanker series. The
implications of this will be discussed further.
J-20 capability assessment The
shaping of the J-20 prototype has important
implications from the perspectives of aerodynamic
performance and stealth.
The delta canard
configuration of the J-20 design is common to the
earlier Chengdu J-10, the European Eurofighter
Typhoon, the French Rafale and the prototype of
the Russian MiG I.42 super cruise fighter. This
configuration provides for high supersonic
performance, excellent supersonic and transonic
turn performance, and better short field landing
performance than conventional delta wing designs.
If equipped with suitable engines, a J-20
would be very efficient in supersonic cruise
regime, with excellent close combat maneuver
performance. The intended engine fit has not been
disclosed, although there has been speculation
that the prototype may be fitted with imported
Russian Al-41F1S or Item 117S engines common to
the Su-35S and T-50 PAK-FA prototypes. The Al-41F1
is an evolution of the supersonic cruise engine
developed for the MiG I.42, with a more powerful
Item 129 engine in development for the production
T-50.
There has been some media
speculation about an indigenous engine for the
J-20, designated the WS-15, but no substantial
official disclosures to date.
The detail
airframe stealth shaping design of the J-20 is
clearly based on shaping design rules developed by
the United States, and employed primarily in the
F-22A Raptor, but with an engine inlet design
closer to the F-35 Joint Strike Fighter. This is
important insofar as most radar signature
improvement in stealth designs is a result of
shaping, with radar absorbent materials and detail
design employed primarily to "clean up" unwanted
reflections that could not be suppressed by
shaping.
Qualitative and quantitative
analysis performed by the author indicates that
the J-20 has the potential to yield much better
stealth performance from the front and sides than
the F-35 Joint Strike Fighter, and possibly as
good as the F-22A Raptor, should Chinese designers
master materials and detail design techniques
adequately.
The design has only two
apparent weaknesses, which are the curvature in
the slab side shaping, which provides broader
reflection lobes than necessary, and the circular
exhaust nozzle, a weakness common to the F-35 and
T-50. Both may be artifacts of the prototype and
may not be features of a future production
aircraft.
The shaping design will be
highly effective against radars operating above
the 1 GigaHertz L-band, but much less effective
below this band. This band coverage encompasses
most surface based and airborne search,
acquisition and fire control radars used by the
United States and its allies in Asia.
A
survey of 26 unclassified English-language Chinese
research papers on radar absorbent materials
indicates a high level of research effort in the
area, but mostly for materials not suitable for
aircraft applications. Research in this area is
usually not published in the West and there is no
reason to believe China would do differently.
The available data support the proposition
that the J-20, once fully developed, will be a
high performance stealth aircraft, arguably
capable of competing in most cardinal performance
parameters (ie speed, altitude, stealth, agility)
with the United States F-22A Raptor, and superior
in most if not all cardinal performance parameters
against the F-35 Joint Strike Fighter.
The
intended role of the J-20 has not been disclosed
officially, and widely varying views have been
expressed by various observers.
The
suitability of this design for various roles will
depend primarily on what engines are installed,
and whether faceted stealthy exhaust nozzles
modeled on the F-22 design are employed, the
latter being important for deep penetration
through air defense systems.
If the
engines deliver 40,000-50,000 lb class thrust
performance, the J-20 will be viable as an air
combat fighter, air defense interceptor and deep
strike fighter. If thrust performance falls below
this benchmark, the aircraft would lack the
agility for close air combat, but still be very
effective as an interceptor or bomber.
What this suggests is that if Chinese
engine technology has not matured enough by the
latter half of this decade, when IOC is planned
for the J-20, early variants could be employed as
strike aircraft, or interceptors, with later
variants "growing" into the air combat role as
more powerful engines become available.
China has deployed or developed a range of
new guided weapons suitable for internal carriage
by the J-20. While no imagery as yet exists
showing the configuration of the J-20 internal
bays, the aircraft layout could permit a similar
arrangement to the F-22A, but with a longer and
deeper fuselage bay capable of carrying larger
bombs, or even more weapons.
Richard
Fisher at the International Assessment and
Strategy Center has detailed a number of Chinese
5th Generation Air-Air Missiles, including evolved
variants of the PL-12, modeled on the United
States AIM-120 AMRAAM, the ramjet powered "PL-13"
modeled on the European MBDA Meteor, and the agile
thrust vectoring PL-ASR/PL-10, modeled on the
A-Darter and Iris-T missiles.
Guided bombs
suitable for strike against surface targets are
also abundant. At the Zhuhai and CIDEX 2010 arms
expos, Luoyang/CASC (China Aerospace Science and
Technology Corporation) displayed a range of new
guided bomb designs.
These include the
"Lerting" (Thunderbolt) LT-3, which is modeled on
the US GBU-55/56(V)/B Laser JDAMs, the FT-1, FT-3
and FT-5 modeled on the US GBU-32/35/38 JDAM
satellite aided bombs, and the winged FT-2, FT-4,
FT-6 and LS-6 planar wing glide bomb variants,
broadly modeled on the Australian JDAM-ER glide
bomb family. The LS-6 family also includes 50 kg
and 100 kg small bombs, modeled on the US Small
Diameter Bomb series, but with cruciform strakes
rather than planar wings.
The heavy
emphasis placed by Luoyang/CASC on glide bombs is
important, as these can be released by stealth
aircraft from ranges well outside the detection
range of the aircraft itself, which can thus
remain unseen through the whole delivery maneuver,
effecting complete surprise.
The strategic
impact of a mature production J-20, even if
limited to strike roles alone, would be profound.
With sufficiently good stealth performance to
defeat air defense radars in the L-band through
Ku-band, the aircraft could easily penetrate all
air defense systems currently deployed in Asia.
Even should the aircraft be tracked by a
counter-stealth radar, the high altitude
supersonic cruise penetration flight profile makes
it extremely difficult to engage by fighter
aircraft and Surface to Air Missiles. The only
fighters deployed in the Pacific Rim with the raw
performance to reliably intercept a supersonic
J-20 are the F-22A Raptor and Russian MiG-31
Foxhound.
The size of the J-20 and
resulting fuel fraction indicate that the aircraft
will be able to cover the "First Island Chain"
without aerial tanker support, and with tanker
support, reach targets across the "Second Island
Chain" on subsonic cruise profiles. Nearer targets
would be accessible on supersonic cruise profiles.
The impact of the J-20 There
can be no doubt at this time that a mature
production J-20 with fully developed stealth and
supersonic cruise capability would qualify as a
"game changer" in the Asia-Pacific region.
The J-20's combination of stealth and
supersonic cruise - the cardinal design feature of
the F-22A Raptor - provides the capability to
defeat nearly all extant Integrated Air Defense
Systems. Defeat is effected by denying detection,
and should detection occur, by kinetically
defeating launched missiles, which cannot close
with the target before it exits radar tracking
range.
Even without stealth, high-altitude
supersonic aircraft are challenging targets for
all but the largest and longest ranging
surface-to-air missiles. Interceptor aircraft
without a capability for sustained supersonic
flight are typically ineffective against
high-altitude supersonic targets.
The
development of the J-20 around the combination of
stealth and supersonic cruise results in a design,
which will be undetectable at range by almost all
air defense radars operated by the United States
and its numerous allies in the Asia-Pacific
region. In practical terms, this results in the
"block obsolescence" of most Asian air defense
systems.
Another important consideration
is that the J-20 is a large fighter and therefore,
if flown on fuel efficient subsonic cruise
profiles, will be able to reach targets at ranges
of around 1,000 nautical miles without aerial
refueling tanker support.
If flown from
PLA airbases along the eastern seaboard of
mainland China, the J-20 will thus be able to
comfortably reach any target within China's "First
Island Chain", unrefueled. These targets include
airfields in Japan, South Korea, and former US Air
Force airbases in the Philippines.
With
modest aerial refueling support, the J-20 will be
able to reach most targets situated along China's
"Second Island Chain", including the strategically
critical Guam facilities.
The strategic
choices available to the United States and its
allies for dealing with the J-20 are very limited;
such is the potency of all aircraft combining
stealth and supersonic cruise capabilities.
These distill down to the deployment of
large numbers of F-22A Raptor fighters in the
region, and the development and deployment of
"counter-stealth" radars operating in the HF, VHF,
and UHF radio-frequency bands. Funding for the
production of the F-22A was stopped in 2009,
following an intensive political effort by
Secretary of Defense Robert Gates. There is no
program to fund the development and volume
production of "counter-stealth" radars.
The incumbent US administration has thus
committed itself politically to a path in
developing air power for the US armed services and
allied air forces, predicated wholly on future
opponents operating obsolete Soviet-era air
defense weapons and fighters. The unveiling of the
Russian T-50 PAK-FA and Chinese J-20 over the past
two years has not produced any significant changes
in US planning, which may challenge the United
States and its Pacific Rim allies' strategic
advantage in conventional air power.
Carlo Kopp, PhD, is head of
capability analysis with the Air Power Australia
think-tank, a research fellow in regional military
strategy at the Monash Asia Institute, and an
active researcher in computer networking,
satellite navigation and radar theory at the
Monash Faculty of IT in Melbourne, Australia. He
is a leading authority on Russian and Chinese
weapons technology.
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