Chinese J-20 Stealth Fighter Not So Advanced After All

The initial concern over China's stealth fighter may have not been warranted according to this report.

China’s newest combat aircraft prototype, the J-20, will require an intense development program if it is going to catch up with fast-moving anti-stealth advances.

In fact, anti-stealth will bring into question all stealth designs: How much invulnerability will current low-observability techniques offer as air defense systems adopt larger and more powerful active, electronically scanned array (AESA) radars? From the early days of AESA development, a key goal was to build a radar that could detect very small objects—such as a cruise missile at a distance great enough to target and shoot it down—or a larger object like a fighter with a very low-observable treatment.

Airborne detection of stealth aircraft may already be an operational capability. In a series of tests at Edwards AFB, Calif., in 2009, Lockheed Martin’s CATbird avionics testbed—a Boeing 737 that carries the F-35 Joint Strike Fighter’s entire avionics system—engaged a mixed force of F-22s and Boeing F-15s and was able to locate and jam F-22 radars, according to researchers. Raytheon’s family of X-band airborne AESA radar—in particular, those on upgraded F-15Cs stationed in Okinawa—can detect small, low-signature cruise missiles.

Moreover, Northrop Grumman’s lower-frequency, L-band AESA radar on Australia’s Wedgetail airborne early warning and control aircraft is larger and potentially more capable of detecting stealth aircraft at longer ranges.

Lockheed Martin also hinted at a JSF anti-stealth capability in 2009 in a reference to combat with sophisticated, foreign aircraft. “The F-35’s avionics include onboard sensors that will enable pilots to strike fixed or moving ground targets in high-threat environments, day or night, in any weather, while simultaneously targeting and eliminating advanced airborne threats,” said Dan Crowley, then-executive vice president and F-35 program general manager.

Better images emerging from China point clearly to the J-20’s use of stealth technology, but major uncertainties and questions remain unresolved.

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The biggest uncertainty about the Chinese design concerns the engine exhausts, which as seen on the prototype are likely to cause a radar cross-section (RCS) peak from the rear aspect. One possibility is that a stealthier two-dimensional nozzle will be integrated later in the program; however, the nozzles on the current aircraft show some signs of RCS-reducing sawtooth treatment, suggesting that the People’s Liberation Army has accepted a rear-aspect RCS penalty rather than the much greater weight and complexity of 2D nozzles.

By: Shelldrake