Kamov Ka-25

Kamov
Industry	Aerospace, Defense
Founded	1958
Headquarters	USSR
Products	Kamov Ka-25 naval helicopter

Template:Infobox aircraft

The Kamov Ka-25 (known by its NATO reporting name as "Hormone") is a naval helicopter created specifically for the Soviet Navy in the USSR beginning in 1958.

Design and development

During the late 1950s, there was a pressing requirement for anti-submarine helicopters capable of operating from newly commissioned vessels featuring helicopter decks within the Soviet Navy. Kamov’s compact design was selected for production in 1958. To accelerate development, Kamov constructed a prototype to validate the cabin layout and dynamic components; this model, designated the Ka-20, lacked mission-specific equipment, corrosion protection, and shipboard operational systems. The Ka-20 was publicly exhibited at the 1961 Tushino Aviation Day.

The finalized Ka-25 prototypes included mission apparatus and structural corrosion resistance. The rotor system featured aluminium alloy blades filled with nitrogen to detect cracks, lubricated hinges, hydraulically powered controls, alcohol-based de-icing, and an automatic blade folding mechanism. Propulsion came from two free-turbine engines mounted above the cabin with electrically de-iced air intakes and simple side exhausts without infrared countermeasures. These engines drove the main gearbox directly, which was cooled by a fan along with hydraulic oil coolers located aft. The airframe utilized stressed skin construction made of duralumin with flush riveting, supplemented by bonding techniques and honeycomb sandwich panels.

The cabin measured 1.5m by 1.25m by 3.94m and featured a sliding door on the port side; the flight deck was positioned forward of the cabin. Fuel tanks located beneath the floor were refueled via a pressure nozzle on the port side. At the rear of the cabin, a short boom supported a central vertical fin and twin inward-angled fins at each end of the tailplane, primarily aiding autorotation. The landing gear consisted of two fixed main wheels with sprag brakes mounted on parallel 'V' struts connected to the fuselage, each equipped with an angled shock absorber to absorb landing impacts. Two castoring nose wheels on straight shock-absorbing legs were attached beside the cockpit; these folded rearward to minimize RADAR interference. All wheels were fitted with emergency rapid inflation flotation collars.

Flight controls operated through the coaxial rotors: pitch, roll, and collective inputs functioned similarly to those on a conventional single rotor helicopter. Yaw control was achieved via differential collective pitch, which also influenced torque. An automatic mixer ensured total rotor lift remained constant during yaw maneuvers to enhance handling during deck landings. Optional equipment included foldable seating for twelve passengers, a rescue hoist, external auxiliary fuel tanks, or containers designed for cameras, flares, smoke floats, or beacons.

Variants

Ka-25BSh: (NATO reporting name 'Hormone-A') These variants serve primarily in the anti-submarine warfare capacity, outfitted with radar, a dipping sonar system, a towed MAD, and armed with torpedoes along with either nuclear or conventional depth-charges.
Ka-25BShZ: A mine-clearing variant, with a total of eight units produced.
Ka-25C: An obscure upgrade with limited available information.
Ka-25F: A proposed assault helicopter competing against the Mi-22 and the larger Mi-24. It features a glazed nose, a cargo area accessible through four doors, an under-fuselage turret mounting a GSh-23L, and capability to carry up to six 9M17 Phalanga anti-tank missiles, or six UB-16 rocket launchers, each loaded with 16 S-5 rockets, or bombs.
Ka-25Ts: (NATO reporting name 'Hormone-B') Designed for Over The Horizon targeting, this version transmits data to cruise missiles launched from both surface vessels and submarines. Its anti-submarine gear, Electronic Surveillance Measures, and weapons bay were removed to accommodate a larger radar scanner/reflector housed within a prominent radome beneath the nose. Distinguishing features include semi-retractable landing gear and a small cylindrical data-link antenna located under the rear fuselage.

File:Kamov Ka-25K CCCP-21110 Le Bourget 03.06.67 edited-2.jpg

Kamov Ka-25K in Aeroflot livery at the 1967 Paris Air Show

Ka-25K: A civilian flying crane helicopter equipped with a gondola mounted beneath an extended nose for managing slung loads up to 2,000 kilograms (4,400 lb). It includes electrically de-iced rotor blades and optional seating for 12 passengers. Only one prototype (SSSR-21110) was flown in 1966.
Ka-25PS: (NATO reporting name 'Hormone-C') This search and rescue plus transport variant lacks a weapons bay but retains the radome found on the Ka-25BSh. Standard equipment includes seating for 12 personnel, a rescue winch, stretcher accommodations, and auxiliary fuel tanks. Optional fittings include a homing receiver, Electronic Surveillance Measures, searchlight, and loudspeaker system. Typically, Ka-25PS units were painted in red and white.
Ka-25T: (NATO reporting name 'Hormone-B') Possibly an incorrect or misapplied designation referring to the Ka-25Ts Over The Horizon targeting relay aircraft.
Ka-25TL: A missile tracking model also known by the designations Ka-25TI and Ka-25IV.