YingJi-91 (Kh-31P) Anti-Radiation Missile

The Kh-31P (NATO reporting name: AS-17C Krypton-C) is the anti-radiation missile (ARM) developed by the Russian Zvezda Bureau, based on the Kh-31A (AS-17A) supersonic anti-ship missile. The PRC obtained some examples of the Kh-31P in the late 1990s, and is reportedly producing the missile locally as YingJi-91 (YJ-91). It is not known whether the YJ-91 production has been licensed by Russia. However, other sources suggested that the PRC imported some Kh-31P missiles from Russia between 2002 and 2004, possibly due to the delay in the YJ-91 development.

The PRC reportedly obtained several non-flying examples of the Kh-31P in the late 1990s for testing and study. This was confirmed by a photo published anonymously on Chinese Internet, showing a Kh-31P missile in a Chinese factory. It was reported that the PRC was developing YJ-91, a licensed copy of the Kh-31P, though the claim was denied by the Zvezda Bureau. During 2002~2004, the PLA reportedly purchased an unknown number of the Kh-31P missiles from Russia to arm its Su-30MKK fighters, which contradicts the previous report that an indigenous copy was being produced.

Nevertheless, either Kh-31P or its Chinese copy YJ-91 has been serving with the PLAAF since 2003~04. The missile provides the PLAAF with an advanced medium-range standoff anti-radiation strike capability, which was not previously possessed by the force. The Kh-31P was originally developed for the Soviet Air Force specifically against the U.S. Patriot air defence missile system. The missile is capable of suppressing enemy air defence systems and make its early warning ‘blind’ by striking their radar. Zvezda Bureau is also developing an improved 200km-range model which can directly attack enemy AEW or AWACS systems.

Design

The Kh-31P features a long slim cylinder body with a sharp nose, with four rocket boosters attached at the rear half of the missile. There are four clipped delta wings and four smaller tail surfaces of similar shape organised in cruciform configuration around the fuselage. Internally the L-112E radar seeker (D~F band) is in the nose with the guidance system, batteries and radio altimeter in the remainder of the front compartment, and the 87kg HE warhead immediately behind. A fuel tank, presumably with a kerosene-type fuel, occupies the area to the leading edges of the wing and the area almost to the rear edges is occupied by the ramjet. Much of the rear of the missile is occupied by a solid propellant booster through which runs the ramjet nozzle. Actuators are to be found below the tail surfaces.

Propulsion

The Kh-31P features a unique dual propulsion system designed by the Soyuz Design Bureau in Turayevo near Moscow. First the missile is accelerated by its solid-fuel rocket engine to a speed of Mach 1.8, then the engine is discarded and the interior of the missile is converted into the combustion chamber of the missile's jet engine. The latter accelerates the missile to a speed of almost Mach 4.5, while four air intake holes on the sides of the missile body open up.

Specifications

Length: 5.21m
Diameter: 0.36m
Wingspan: 1.15m
Weight: 600KG
Warhead: 87Kg HE
Propulsion: Ramjet + integral solid rocket boosters
Max speed: Mach 4.5
Max effective range: 110km
Guidance: L-112E passive radar homing, D~F band

Last update: 20 October 2008