If ever there were an aircraft that should grow in capability,
China's newly flown Y-20 airlifter would be it. The prototype that took
to the air on Jan. 26 mates what looks like a modern airframe with
obsolete 1960s-technology engines. Together, they probably represent no
more than a serviceable design standard, offering only modest advances
in capability over the Ilyushin Il-76 that China already operates.
a better engine is under development for the Y-20. If and when China's
technologically challenged aero-engine industry can get that high-bypass
turbofan ready, then the airlifter should surge in performance. More
distantly, a truly modern engine under development for the Comac C919
airliner could also be available.
Successful development of the
Y-20 airframe is in itself an important accomplishment for the Chinese
industry, which in more than six decades of Communist history has been
only slowly and haltingly weaning itself from copying foreign types,
mostly Soviet-era Russian designs. Underscoring this point, the Y-20 is
the largest indigenous Chinese aircraft built so far, exceeding the
unsuccessful Y-10 airliner tested in the early 1980s.
will not enter service before 2017, according to two Chinese military
academics, Zhang He and Li Wei, writing in China Youth Daily, a major
national newspaper. They also say that the Y-20 airframe incorporates
composite materials (although most of it appears to be aluminum) and a
“supercritical” wing. It is not clear whether the objective is to have a
new engine ready by service entry.
The Y-20 is an entirely new
design, even though it is close in size and shape to the Il-76, which
uses the same Saturn D-30KP medium-bypass engine as the Chinese
airlifter's prototype. Compared with the Il-76, the Y-20 has a shorter
wingspan and a shorter, but slightly wider, fuselage. The Y-20 is larger
than the Airbus A400M and has about the same fuselage diameter, but is
much smaller than the Boeing C-17.
Specifications estimated by
Aviation Week (see table) and including dimensions determined
photometrically, vary from figures quoted by Zhang and Li. The academics
say the Y-20's span is 45 meters (148 ft.), length 47 meters, height 15
meters, gross weight “over 200 tons” and payload 66 tons. They give no
source, but their figures could be preliminary numbers estimated in
2006, when the project was launched after about 15 years of study.
Comparison with the Il-76 suggests that the published weight and payload
figures are too high for a version fitted with the D-30KP.
late 2009, Hu Xiaofeng, the general manager of Avic Aircraft—the
large-airplane specialist subsidiary of aeronautics group Avic—said the
Y-20 was in the “200-ton class” and would be unveiled at the end of that
year. But it was not unveiled then, suggesting that the airframe or
engine program had hit trouble. The Xian Aircraft plant is building the
Y-20, which was rolled out in December 2012.
The Y-20 follows the configuration set by the Lockheed C-141, with a
high-mounted wing, moderately swept to combine good low-speed
performance with reasonable cruising speed, fuselage-mounted landing
gear and a T-tail. (Since the C-141, all successful jet airlifters have
used that configuration, except the An-124, which has a low tail.) The
Y-20's wing has full-span slats and triple-slotted trailing-edge flaps,
the latter comprising two articulated segments with a fixed vane on the
forward surface. The engines are hung low as on the Il-76—in its current
form at least, the Y-20 does not use externally blown flaps in the same
way as the C-17.
The ailerons can also droop to increase lift
at low speeds, and large spoilers are fitted for roll control and lift
dumping. Like the C-17, the Y-20 has a four-piece rudder, with upper and
lower double-hinged segments. This provides both redundancy and the
ability to use higher deflection on the lower half than on the upper
rudder panels, reducing loads on the vertical tail.
comparison with the Il-76, a smaller cockpit for just three crew members
should have helped designers to increase cargo volume. Chinese media
stress that the aircraft is fatter than the Il-76, the skinniest of the
strategic airlifters now in service, though the difference may not be
great. Extra diameter should help in stowing outsize items such as
helicopters and engineering vehicles, but the Y-20's cargo bay is
shorter than the Il-76's.
The landing gear looks similar in
layout to the A400M's, with three separate twin-wheel units on each
side. Operating jet airlifters from truly unimproved surfaces is more
spectacular than practicable, but the Y-20 should be as good as any of
its contemporaries in this regard. Zhang and Li say it can operate from
“relatively simple” fields. The nose wheel can pivot 90 deg., they add,
giving a detail that suggests they have been well-briefed. (Zhang is on
the faculty of the Command College of the Second Artillery and Li is of
the National Defense University.)
The Y-20's overall size and
weight are such that it could be an effective aircraft with D-30KP
engines, which China already imports for its H-6K cruise-missile
carrier. At least 20% more thrust will probably be available from the
Chinese turbofan that Avic Engine is developing at Shenyang, possibly
under the name WS-20. It is believed to be a derivative of the WS-10
Taihang fighter engine.
In contrast to the medium-bypass D-30KP,
it will have a high bypass ratio, making it comparable with the CFM56,
to which it may be related (AW&ST Nov. 7, 2011, p. 28). The Y-20
must have entered flight testing with the D-30KP because the Chinese
engine was not ready—perhaps not fully developed or maybe just not
trusted for early flights.
A more distant prospect is the
CJ-1000, which Avic Commercial Aircraft Engines is developing for the
Comac C919 airliner as an alternative to the CFM Leap-1 and with the aim
of matching the performance of that Franco-U.S. engine. CJ-1000
development faces great technical challenges but is probably being well
funded. With abundant thrust and, it is hoped, world-class efficiency,
the CJ-1000 would transform the performance of the Y-20.
prospective use of the Y-20 raises a contradiction that has become
familiar as the Chinese navy has developed its amphibious assault
capability and commissioned an aircraft carrier. China's government
consistently downplays its interest in power projection. And, like all
authoritarian states, it strongly promotes the principle of
non-intervention in the internal affairs of other countries. No wonder,
then, that state media stress the humanitarian and disaster-relief role
of the Y-20. Those will undoubtedly be prominent roles of the Y-20,
internationally as well as domestically, helping China's image abroad.