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U.S. Air Force photo TSgt Brandon Shapiro
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October 30, 2017
Since early 2011, China has been testing the large multirole J-20
strike fighter/interceptor. According to the 2011 Pentagon report on Chinese
military power, China was attempting to introduce stealth, advanced avionics,
and supercruise capability to the J-20, which would give it an increased
ability “to strike regional air bases, logistical facilities, and other
ground-based infrastructure,” as well as giving “the PLA Air Force a platform
capable of long range, penetrating strikes into complex air defense
environments.” The 2016 edition of the Pentagon report stated that the J-20 had
“modern avionics and sensors that offer more timely situational awareness for
operations in network-centric combat environments, radars with advanced
tracking and targeting capabilities, protection against enemy electronic countermeasures,
and integrated EW systems.” China’s state media have recently confirmed press
reports that the J-20 is operational.
General
Based on photographs available, the J-20 appears to be larger than
the U.S. Air Force F-22, which is larger than the F-35. According to aviation
journalist Piotr Butowski, the J-20 design “indicates the priority of speed and
range over maneuverability.” 1 It
appears optimized for a speed of Mach 1.2 to Mach 1.8. The wing area of the
J-20 is about
25 percent less than the F-22 , with wing loading almost
identical to the F-35. 2 Apparently,
it does not have a gun. Aviation journalist Andreas Rupprecht states that its
maneuverability is at least comparable to the Chinese J-11B (a Su-27/Su-33
Flanker derivative). 3 This
implies it has good fourth generation maneuverability and may be more
maneuverable than the F-35, which was not designed to be more maneuverable than
the F-16 or the F-18. Absent a gun, an advantage in maneuverability is less
important, although its ability to carry the Chinese version of the Sidewinder
internally is a significant advantage in close range combat.
The J-20 should have long range, particularly when its current
engines are replaced. Former head of the Russian Air Force Colonel General
Alexander Zelin, says its combat radius is approximately 1,250 miles. Photographs
of the J-20 show it carrying four large external fuel tanks and dropping them
and their pylons, giving it the potential to increase range or loiter time
substantially and allowing it to reconvert to stealth mode in flight.
Weapons
The J-20 is reported to carry a long-range air-to-air missile that
could hit aircraft at ranges up to 180 miles. A photograph shows it being
carried externally, and at some point such a missile could be carried
internally. The J-20 clearly represents a threat to AWACS, tanker aircraft, and
fourth-generation fighters. In large numbers, it could be a threat against the
F-22 and F-35. Its large bomb bays could allow it to launch air-to-ground or
antiship missiles beyond the detection range of U.S. systems.
Aviation Week reports that one of the J-20’s missions appears to be
maritime reconnaissance and targeting for antiship ballistic missiles and in
support of ship-launched cruise missiles. Its large weapon bays will enhance
its ability as a strike-fighter, making it a serious long-range threat to land
and naval targets. It reportedly can be armed with a precision air-to-surface
missile with a 600-mile range. 4
Stealth
Like the Russian Pak FA, the J-20 apparently lacks some attributes
of a 5th generation fighter. Mikhail Pogosyan, president of Russia’s United
Aircraft Corporation and Sukhoi Company, commented, “As for the development of
a genuine 5th generation combat aircraft, China obviously has a long way to
go.” 5 This
is an apparent reference to China’s problems developing advanced engines and
avionics.
Lieutenant General David Deptula, U.S. Air Force (Retired), said
that the J-20 appears to be more advanced than Russia’s Pak FA and “it may have
some significant low-observable capabilities on the front end, but not all
aspects—nor is it built as a dogfighter.” The J-20 has been characterized as
having medium stealth with its best performance from the front and the worst
from the rear. Business Insider quotes a senior scientist at Lockheed Martin as
saying, “It’s apparent from looking at many pictures of the aircraft that the
designers don’t fully understand all the concepts of LO [low observable]
design.” 6 John
A. Tirpak, executive editor of Air Force Magazine, wrote that the J-20 “may, in
fact, be a stealthy strike platform, designed to be just stealthy enough to get
close to a target, launch missiles, and retreat quickly.”
Current Air Force Chief of Staff General David Goldfein has
compared the J-20 to the F-117, which reportedly had a radar cross section of
.269 square feet. 7 If
true, the J-20 stealth level is first generation. Andreas Rupprecht writes “The
J-20 is most likely no match for the F-22 and the F-35… On the other hand, it
is surely far stealthier than most other types of aircraft operational in the
Asia-Pacific area.” 8
By comparison, the official description of the stealth level of the
F-35 is that of a metal golf ball. Aviation Week reports that the F-35 RCS is
-30 dBsm or .001 square meters. 9 The
F-35 is reported to be stealthier than the F-22 from the front, although it is
generally said to have a less uniform RCS than the F-22. If true, the F-35
probably has a one-to-two order of magnitude advantage in stealth over the
J-20, giving it a first shot/kill advantage in a one-on-one confrontation. This
does not consider the F-35’s networking, data fusion, and electronic warfare
capabilities, which likely increase its advantage considerably.
Engines
The 2014 Pentagon report on Chinese military power observed, “China
faces numerous challenges to achieving full operational capability, including
developing high-performance jet engines.” The flight characteristics of the
J-20 are limited by inadequate engines because of delays in the development of
the Chinese WS-15 engine, which is supposed to have about 40,000 pounds of
thrust and thrust vectoring. The prototypes of the J-20 seem to be equipped
with Russian AL-31FN engines, which lack thrust vectoring or adequate power to
achieve supercruise speed or high maneuverability. 10
To compensate for the WS-15 problems, China is procuring the
Russian Su-35 fighter to get its 117S engines, the most advanced Russian
fighter engines. The sale of Su-35s to China was long delayed by Russia’s
concern about Chinese reverse engineering. The Russian engine, however,
reportedly will not have enough thrust to give the J-20 supercruise capability,
though it will improve aerodynamic performance and provide thrust vectoring.
Lockheed Martin says the F-35 has a limited supercruise capability
(150 miles at Mach 1.2.) giving it an advantage over the current J-20. If the
F-35 thrust is increased through engine improvements, this should increase its
supercruise potential and give it an advantage even over a J-20 equipped with
the Russian engines.
Sensors
The J-20’s sensor capabilities appear to be impressive. In addition
to its active electronically scanned array (AESA) radar, the Chinese appear to
have copied the stealthy electro-optical targeting system sensor housing from
the F-35. The J-20 reportedly also has a 360-degree optical counterpart to the
F-35s distributed aperture system. Just because it looks the same does not mean
that it works the same. While the J-20’s AESA radar probably gives it enhanced
detection against low RCS targets (compared to passive array or mechanically
scanned radars), not all AESA radars have the same power and capabilities,
including stealth, electronic protection, and electronic warfare capability.
According to press reports, the F-35’s APG-81 radar operates “in LPI (low
probability of intercept) and LPD (low probability of detection) modes that
minimize the aircraft’s signature to comply with its low observable (LO)
requirements. The radar is optimized for agility, very low noise, high
efficiency, and fully supports the LO nature of the aircraft.” 11Since
the J-20 radar is an early Chinese AESA, it is unlikely to be in the same class
as the radar on the F-35. Moreover, it is unlikely China can match the “flying
super computer” capabilities of the F-35, including sensor integration and
networking to improve pilot situational awareness.
Assessment
In 2015, then-chief of the F-35 joint program office Lieutenant
General Christopher Bogdan, U.S. Air Force, commented, “I’d put this airplane
up against any airplane in the world today, tomorrow and for the next 20 or 30
years, and we will come out ahead.” The Air Force says the F-35 achieved 110
“kills” against “adversary aircraft” in Exercise Northern Lightning and
achieved a 20-to-1 kill ratio in the early 2017 Red Flag exercise. Marine
F-35Bs reportedly suppressed SAM sites without being targeted.
Overall, the J-20 is likely to be a serious threat to U.S.
aircraft, ships, and bases for the foreseeable future. While the F-35 has
better stealth and sensor capability and the J-20 may not be a matchup
one-on-one, the Chinese may be able to put more of them in the sky. In 2017,
General Herbert Carlisle, Commander Air Combat Command, stated that in the
South China Sea the threat may be “10 squadrons of J-20s, plus Su-35s…and
Su-30s and J-10s and J-11s.” So, while not as good as the F-35, the J-20 does
not have to be as stealthy or have sensor parity to have an impact on the Far
East military balance.
Original post: realcleardefense.com
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