The Kamov Ka-31 (NATO reporting name 'Helix') is a military helicopter developed by Kamov Joint Stock Company (then, Kamov DB) for the Soviet Navy and currently in service in Russia, China and India in the naval airborne early warning and control role. The main mission of the helicopter is long-range detection of threats, including airborne threats such as fixed-wing aircraft and helicopters.
Surveillance, target tracking and transmission of the target data to the command posts is carried out onboard the helicopter. The early provision of hostile target information increases the combat efficiency of naval, air defence and land forces.
As with all Kamov helicopters except the Ka-60/-62 family, the Ka-31 has co-axially mounted contra-rotating main rotors. The airframe of the Ka-31 is based on the Kamov Ka-27. Originally this helicopter was known as the Ka-29RLD (Radiolokatsyonnogo Dozora, or radar picket helicopter).
Development
The Kamov Ka-31 series of medium-lift navalized helicopters was born out of a Soviet Navy need for an interim Airborne Early Warning platform while resources went to the proposed dedicated Antonov An-71 "Madcap". The An-71would have operated directly from the flight decks of the limited Soviet carrier force but was cancelled when interest fell to the Yakolev Yak-44 solution. The Yak-44 itself would have been another fvixed-wing design launching from Soviet carriers but the fall of the Soviet Empire led to a cancellation in its development. Three An-71 prototypes were completed whilw only a full-scale mockup of the Yak-44 ever saw light of the day. This upheaval then paved the way for modified form of the trusted-and-true Kamov Ka-27 "Helix" shipborne, twin-rotor,anti-submarine helicopter series known as the "Ka-29". design work began in 1980. The radar development took time and it was not until 1987 the first flight took place. The production version of the Ka-29RLD/-31 was very different from the Ka-29 from which it was derived. The development and trials began in 1987 in earnest, but they were plagued by the political turmoil and the defense budget cuts in the late 1980s and the early 1990s. Finally the aircraft entered service in very limited numbers with the Russian Navy in 1995 with its Admiral Kuznetsov class aircraft carrier and Sovremenny class destroyers.
The Ka-31 naval helicopter, as in all Kamov helicopters except the Ka-60 and 62 family, has co-axially mounted contra-rotating main propellers. The airframe of the Ka-31 is based on the proven and highly successful Ka-27; one visually distinctive feature of the Ka-31 is the large antenna of the early warning radar, which is either rotating or folded and stowed under the fuselage.
The landing gear retracts in order to prevent interference with the radar.
The early warning radar, E-801M Oko ('Eye'), was developed by the Nizhny Novgorod Radio Engineering Institute. The 6m² radar antenna is stowed flat against the underside of the fuselage until deployed. The TA-8Ka APU (Auxiliary power unit) is added to provide power for the radar and C4ISR
The navigator switches on the radar system and the antenna extends, turning through 90° from the horizontal to the vertical plane. In operation the antenna rotates at 6rpm. Once the navigator has switched the radar system to operational mode, the system works autonomously without operator control. The navigator monitors the target observation on a display.
The radar has 360° azimuthal coverage. The surveillance range against a fighter aircraft size target is up to 150km.
The surveillance range against a surface ship is typically 100km to 200km. The radar is capable of simultaneously tracking 30-40 targets. Helicopter has a datalink to transfer the target tracking data to the command post (land base or mother ship). The Ka-31 is fitted with GPS and digital terrain mapping systems.
When the radar surveillance phase of the mission is completed the antenna is retracted to the storage position. The antenna is fitted with explosive bolts enabling it to be jettisoned quickly in an emergency, such as in preparation for a forced landing.
The flight deck of the Ka-31 naval helicopter is wider than that of the Ka-27, with 2 additional MFDs and accommodates two crew, the pilot and the navigator. The cockpit is armour protected.
The navigation suite includes a Kronstadt Kabris 12-channel global positioning system, digital terrain mapping, ground-proximity warning and obstacle approach warning. 16-channel digital communication gear with range up to 250 miles (400 km).
Armament
Four-barrel Gatling-type GShG-7.62 7.62mm machine gun, with 1,800 rounds, flexibly mounted behind down ward-articulated door on starboard side of nose; four pylons on outriggers, for two four-round packs of 9M114 Shturm (AT-6 'Spiral') ASMs and two UV-32-57 57 or B-8V20 80mm rocket pods. Alternative loads include four rocket packs, two pods each containing a 23mm gun and 250 rounds, or twn ZAB 500 incendiary bombs. Internal weapons bay for torpedo or bombs. Provision fur 30mm Type 2A42 gun above port outrigger, with 250-round ammunition feed from cabin.
Klimov TV3-117VMAR turboshaft engines
The helicopter is powered by two Klimov TV3-117VMAR turboshaft engines, rated at 1,633kW each. The fuel tanks are filled with a fire suppressant low-density polyurethane foam material, which prevents the build up of an explosive fuel and air mix and will also suppress fuel loss in the event of severe combat damage.
Power for the radar and antenna is provided by an auxiliary power unit, type TA-8Ka, installed above the rear section of the engine bay. A flight recorder is installed in the tailcone fairing.
KA-31 performance
The Ka-31 has a maximum take-off weight of 12,200kg. The operating altitude is up to 3,500m. The helicopter flies on patrol at 100km/h and the operational range with the antennas in the stowed position is 600km. The mission duration is two hours 30 minutes.
The Indian Navy ordered four Ka-31 radars in 1999, and a further five in 2001. Full-scale volume production of the helicopter started in 2002. The first batch of four entered service with the Indian Navy in April 2003. The second batch were delivered in 2005.
With the Indian Navy becoming a one carrier navy, it not only operated the helicopters from aircraft carriers and destroyers, but also from its shore-based naval air stations. The operation with the Indian Navy revealed a major drawback of the aircraft, its limited endurance/range, the chief element of a Taskforce/Battlegroup. So, HAL was commissioned to experiment and possibly adapt a helicopter-to-helicopter refuelling system. Also, in the Indian service, the aircraft received Abris GPS system featuring a 12-channel receiver and option to employ Differential GPS references, designed by the Kronstad itself.[5]
The later batches featured navigational equipment for digital terrain maps, ground-proximity warning, obstacle approach warning, auto-navigation of pre-programmed routes, flight stabilization and auto homing onto and landing at the parent carrier/base and information concerning the helicopter's tactical situation.
Chinese PLA navy official publication revealed Ka-31 helicopter in Feb 2013. It is reported Chinese Ka-31s are based in naval base in eastern China. Intense training is being conducted to ensure these helicopters will be able to provide service when the first Chinese aircraft carrier enters service.
Specifications (Ka-31)
General characteristics
Crew: Two (Pilot+NSO)
Length: 12.5m
Rotor diameter: 2x 14.50 m (2x 47 ft 7 in)
Height: 5.6m
Max. takeoff weight: 12,200kg
Powerplant: 2 × Isotov TV3-117VMAR turboshaft, 1633 kW (2217.7 hp) each
Performance
Maximum speed: 250 km/h (135 knots, 166 mph)
Cruise speed: 205 km/h (110 knots, 126 mph)
Range: 600 km (324 nautical miles)
Service ceiling: 3500 meters (11,483 feet)