China’s heavy stealth fighter-interceptor, the J-20, has rapidly matured over the last half decade, with some reports stating the jet may have reached limited initial operating capability. That term can mean very different things in the Russian and Chinese aerospace and defense communities than it does to their western counterparts. Fielding hardware early on, with minimal capabilities, and developing it in a spiral manner over time by using the operational community as a kind of testing ground, invites higher risk and less than fully vetted capabilities to front-line units. Yet it also offers more immediate results and can be strategically important not just in terms of fielded new capabilities, but also in terms of “optics” both for internal and external consumption.
Regardless of its operational state, the J-20 concept represents a potential threat as it was designed—along with other emerging Chinese aerial weaponry—to exploit weaknesses in American forces’ order of battle and combat doctrine. But the jet also represents a massive leap in Chinese aerospace and manufacturing capabilities and still holds many mysteries—maybe the most pressing among them is the maturity and intended abilities of its integrated avionics suite.
Now an image has emerged that shows how the Chinese are grabbing yet another play right out of modern western fighter development—using a surrogate airliner to act as a flying integrated avionics testbed for their new 5th generation fighter.
China's J-20 avionics testbed seen at the Yanglian flight test center:
The highly modified Russian-built Tupolev Tu-204C looks like a clone to Boeing’s 757-200 prototype turned F-22 integrated avionics testbed—better known as “The Catfish” due to its unique and highly modified nose profile. The Catfish has worked for nearly two decades to test and perfect the F-22’s ever evolving avionics suite.
Boeing's Catfish sits on the ramp at its home at Boeing Field in Washington (Clemens Vasters/Wikicommons):
Built primarily around the Raptor’s APG-77 AESA radar and its equally important ALR-94 electronic support measures suite—but also including its low-probability of intercept data-link, AAR-56 IR/UV missile approach warning system and secure communications systems, among other tactical subsystems—the F-22’s sensor suite and its powerful mission computers were unprecedented in their complexity and capability for their time.
Today the system is rivaled only by the one on the F-35. Much of the development that allowed for all these systems to work together reliably in an automated fashion was done aboard the Catfish. The aircraft features not only the iconic nose profile of the Raptor, but also the aircraft’s swept wing leading-edges, in which conformal antennas are buried. Inside the aircraft, computer workstations, server racks and even a recreation of the F-22 cockpit allow for testing in real flying conditions, including recreating tactical and environmental scenarios F-22 pilots may see in real life.
Catfish was by no means the first avionics testbed. Quite the contrary actually. Surrogate aircraft were used to test avionics, and especially radars, all the way back to World War II. But where the F-22 differed was in its level of “sensor fusion,” that was brought about by deep integration of its various sensors, computers, and communications systems. Before it, fighter avionics were largely “federated,” or systems of their own within a large package of individual systems. As such, Catfish represented a new level of surrogate testbed that was necessary to tackle the huge job of making all the F-22’s systems work together, as if by magic, in an actual airborne environment.
Here is Boeing’s press release from Catfish’s first flight in 1999:
“SEATTLE, March 11—Boeing today began testing the F-22 Raptor's integrated avionics on board its 757 Flying Test Bed. The 757 took off from Boeing Field and tested navigation and sensor emitter management functions.
Testing the Raptor's advanced avionics aboard the company's test bed will help reduce risk, as well as cut back on future F-22 flight test hours by enabling extensive in-flight testing, evaluation and troubleshooting before full avionics suites are installed on F-22 fighters.
The first avionics package, Block 1, which includes the radar and mission software, will be tested on the 757 between March and August 1999. Raptor 4004 will be the first aircraft to fly with its integrated avionics installed, and is scheduled to make its first flight in 2000.
Bob Barnes, Boeing vice president and F-22 program manager, said the
initial test flight went extremely well, adding that testing aboard the
757 will allow early delivery of a better developed avionics package.
"Avionics testing on other fighters has taken 4,000 to 6,000 hours," Barnes added. "We should be able to cut the hours on the F-22 by about 50 percent using our test bed.”
The test avionics are operated from a simulated F-22 cockpit, which has been installed in the test-bed cabin. The cockpit has primary and secondary F-22 displays, as well as a throttle and stick. There is room on the aircraft for up to 30 software engineers and technicians to evaluate the avionics during testing.
Additional modifications to the test bed include installation of an F-22 forward fuselage section to the nose of the plane, and installation of a sensor wing on the plane's crown. The sensor wing was designed and built to simulate the same wing sweep and orientation as an F-22 wing. Additionally, communication, navigation and identification sensors will be mounted directly on the wing to simulate sensor positioning on the F-22's wings.
Boeing is teamed with Lockheed Martin, Pratt & Whitney and the U.S. Air Force to develop the F-22. Boeing supplies the F-22's aft fuselage, wings, radar, 70 percent of the mission software, avionics integration and testing, training and life support systems.”
Since the F-22 became operational over a decade ago, Catfish has continued to play a vital role in supporting upgrades to the jet’s hardware and software, as well as in tactics development to some degree. From time-to-time it will migrate down to Edwards AFB or Nellis AFB for development work, and will even fly alongside other integrated testbeds, like the F-35’s Cooperative Avionics Testbed—nicknamed the CATbird—or those used by Northrop Grumman, Raytheon and other for cross-platform integration.
Knowing all this, it's easy to see why Chinese aerospace firms involved with the J-20’s development have chosen to take an almost identical, and highly proven, route for developing the J-20’s integrated avionics suite. I mean, it’s not like China has any problems with lifting proven designs and aerospace concepts from the US. And just because this testbed aircraft is just now emerging, it doesn't mean it hasn't existed for some time. In fact, most indications point toward the aircraft being fitted with J-20's radar for at least a year—if not two. Nor does it give any indication as to how far along the J-20’s avionics suite, and particularly its radar, is developmentally.
Contact the author: Tyler@thedrive.com