Kamov Ka-25 Hormone

   Designed to meet a 1957 Soviet navy requirement for a new shipborne ASW helicopter, the first member of the Ka-20/25 family was the Ka-20 Harp, which initially flew during 1960. The production Ka-25BSh Hormone-A was of near identical size and appearance, but was fitted with operational equipment and uprated GTD-3F turboshaft engines (from 1973 these were replaced by GTD-3BMs). It entered service in 1967.

   Although the lower part of the fuselage is sealed and watertight, the Ka-25 is not intended for amphibious operations, and flotation bags are often fitted to the undercarriage for use in the event of a emergency landing on the water. The cabin is adequate for the job, but is not tall enough to allow the crew to sand upright. Progressive additions of new equipment have made the interior more cluttered.

   Primary sensors for the anti-submarine warfare mission are the I/J-band radar (ASCC/NATO Big Bulge), OKA-2 dipping sonar, a downward-looking Tie Rod electro-optical sensor in the tailboom and a magnetic anomaly detection (MAD) sensor, either in a recess in the rear part of the cabin or in a fairing sometimes fitted below the central of the three tailfins. A box-like sonobuoy launcher can also be scabbed on to the starboard side of the rear fuselage. Dye-markers or smoke floats can also be carried externally. Comprehensive avionics, defensive and navigation systems are also fitted as standard.

   Armament is not normally carried, although the helicopter can be fitted with a long coffin-like weapons bay which runs along the belly from the radome back to the tailboom, and small bombs or depth charges can be carried on tiny pylons just aft of the nosewheels. The underfuselage bay can carry a variety of weapons, including nuclear depth charges. When wire-guided torpedoes are carried, a wire reel is mounted on the port side of the forward fuselage.

   It has been estimated that some 260 of the 450 or so Ka-25s produced were Hormone-As, but only a handful remains in Russian and Ukrainian service, mostly fulfiling secondary roles. Small numbers of Ka-25BShs were exported to India, Syria, Vietnam and former Yugoslavia, and most of these aircraft still remain in use.

   The second Ka-25 variant identified in the West was given the NATO reporting name Hormone-B, and is designated Ka-25K. This variant is externally identifiable by its bulbous (instead of flat-bottomed) undernose radome and small datalink radome under the rear fuselage. Ka-25K was used for acquiring targets and providing mid-course missile guidance, for ship- and submarine-launched missiles. On the Hormone-B only, the four undercarriage units are retractable and can be lifted out of the scanning pattern of the radar.

   The final version of the military Ka-25 is the Ka-25PS Hormone-C. A dedicated search and rescue (SAR) and transport helicopter, the Ka-25PS can carry a practical load of freight or up to 12 passengers, making it a useful ship-to-ship or ship-to-shore transport and vertrep platform. A quadruple Yagi antenna (Home Guard) fitted to many aircraft is reportedly used for homing on to the personal locator beacons carried by aircrew. Most Ka-25PSs also have searchlight, and a 300-kg capacity rescue winch. Ka-25PS has largely been replaced by Ka-27.