Shaanxi ZDK-03 AEW

Pakistan will receive the first of four Shaanxi ZDK-03 airborne early warning and control system aircraft by the end of January 2011.

The other three aircraft are likely to arrive later in the year, says the Pakistan air force.

"The ZDK-03s have been developed to our specifications," says the air force. "It won't be an E-3C Sentry, but it will have the latest electronics and everything an AEW&C aircraft needs."

The Chinese-built aircraft will have an active electronically scanned array radar, and its open architecture electronics will allow for future developments and upgrades.

Shaanxi Aircraft Industry Corporation based at Hanzhong, Shaanxi Province has been developing an airborne early warning (AEW) aircraft under the codename “Project No.5” since the late 1990s. The aircraft was fitted with a linear-shape active electronically steered array (AESA) radar similar to the Swedish Ericsson PS-890 Erieye. An early prototype using the older Y-8F200 airframe made its maiden flight in November 2001. The finalised design known as KJ-200 based on a Y-8F600 airframe first flew in January 2005. However, the only prototype was lost in an air accident on 4 June 2006, putting the whole development project on hold.

In October 2004, a Y-8F200 turboprop transport aircraft was spotted undergoing modification to be fitted with a linear-shape ESA-type airborne early warning radar at Shaanxi. Later it was revealed that the AEW development programme had been in development since the late 1990s, in parallel with the KJ-2000/A-50I AWACS development project at Xi’an Aircraft Corporation (XAC). With the larger, more sophisticated KJ-2000 performing long-range, comprehensive aerial patrolling and control roles, the smaller KJ-200/Y-8 AEW can provide a less expensive platform for tactical AEW and electronic intelligence roles.

‘Balance Beam’ Radar

The AESA radar, nicknamed “Balance Beam” by military observers, appears to be similar in shape and size to the ERIEYE electronically steered phased-array radar introduced by Ericsson Microwave Systems in the late 1990s. Rather than conventional rotodome antenna system, “Balance Beam” has a fixed, dual-sided and electronically scanned antenna mounted on top of the fuselage. This design is particularly suitable for smaller aircraft with limited space and payload. The radar is capable of 360 degree detection and tracking of air (and possibly surface) targets over the horizon.

It is not clear whether the “Balance beam” radar has any connection to the ERIEYE, but much of the ESA radar technology is available in the ‘off-the-shelf’ commercial market nowadays. Should it have similar performance to the Swedish radar, it would provide a maximum search range of 300~450km. As a phased array radar, the system should be capable of ‘spot’ modes as well as wide search modes, enabling it to be used for ground mapping and targeting acquisition.

Y-8F600 Airframe

The finalised variant of the Y-8 ‘Balance Beam’ AEW system is based on the so-called “Category-III Platform” developed by Shaanxi. The Category-I and -II platform refer to the non-pressurised basic variant Y-8 and pressurised Y-8C respectively. The Category-III platform, also known as Y-8F600 in its commercial name, was incorporated with Western avionic technologies and has been in development since the late 1990s with assistance of Ukrainian Antonov Design Bureau.

Improvements on Y-8F600 include:

Replacing the original three-man cockpit with a more advanced two-man cockpit fitted with modernised avionics including U.S. Honeywell navigation system
Replacing the original ‘glass-in’ nose with a solid nose to accommodate mission equipment
Four Pratt and Whitney Canada PW150B turboprop engines with British Dodi R-408 6-blade propellers
Increased take-off weight and range
Mission equipment pods on wingtips, vertical fin tip and nose