RuAviation

The Ka-25 helicopter made its first flight on 20 June 1961. It was in service with the Soviet Navy for about 30 years and was also widely used for civilian purposes. The Ka-25 was created in the late 1950s at the Helicopter Design Bureau under the supervision of aircraft designer Nikolai Kamov.

Nikolay Ilyich Kamov (1902-1973) graduated from the Tomsk Institute of Technology in 1923. In 1924-1927 he worked at Dobrolyot workshops and later joined the design bureau of D.P. Grigorovich. In 1929 N.I. Kamov together with N.K. Skrzhinsky designed the first gyroplane KASKR-1 “Red Engineer” – an aircraft, similar to a helicopter, which used to create lift capacity by spinning freely in autorotation mode of the main rotor. In 1940 N.I. Kamov was appointed chief designer of the helicopter design bureau that was later named after him.

Ka-25 was a deck-based helicopter with coaxial main rotors. It was equipped with two 900 hp GTD-3F gas-turbine engines developed by the Omsk Engine Design Bureau. Eventually, the power of these engines was recognised as insufficient and from 1972 onwards helicopters were equipped with 1000 hp GTD-3M engines. The Ka-25 helicopter was capable of landing on the deck of a ship in 10° and 3° pitch and roll respectively in 18 m/s wind speed. Besides, it could land on water with the help of multi-section cylinders installed in the undercarriage legs which were filled with compressed air from cylinders in a few seconds.

The helicopter had the following characteristics: take-off weight – 7200 kg, cruising speed – 195 km/h, maximum speed – 220 km/h, flying range – up to 650 km, practical ceiling – 4000 m. Crew included two pilots, payload – 12 passengers or 1300 kg of cargo.

Ka-25 was serially produced in 1965-1973 at Ulan-Ude Aviation Plant No 99. Totally about 460 machines were produced in 18 modifications. The basic model was the Ka-25PL (anti-submarine). It was intended for search and destruction of nuclear submarines of the enemy.

Besides that, the USSR Navy was armed with the Ka-25C target designation helicopter. An all-around radar station (radar) and automatic data transmission system were installed in its nose cowling. This model could patrol the water area at a distance of up to 200 km from the base ship and carry out radar reconnaissance and target search at a distance of up to 250 km. This modification was also used for fixing the coordinates of falling heads during tests of intercontinental ballistic missiles.

The Ka-25BT (trawl tugboat) was used to clear water areas of various mines by trawling. In 1974-1975, after the end of the Arab-Israeli war, the Soviet Ka-25BT participated in the international mine clearance operation of the Suez Canal.

The Ka-25 helicopters have also been widely used for civilian purposes. To move various loads in hard-to-access, forested and swampy terrain the “aerial crane” – the Ka-25K – was created. In the nose of the aircraft from below there was a special cabin for the loading pilot operator. Using a cable attachment and release system, the Ka-25K could transport large-size cargoes weighing up to two tonnes on the external sling and up to 1.5 tonnes inside the fuselage.

In addition, modifications of the Ka-25 were used in agricultural operations. An ambulance helicopter that could transport up to four casualties in prone position was also created.

Ka-25 helicopters have also served the cause of space exploration. In 1968-1970, four Ka-25PS (search and rescue) were involved in the search in the Indian Ocean landers unmanned spacecraft “Probe-5” and “Probe-8”, returned to Earth after flying around the moon.

Nikolay Kamov was awarded the State Prize of the USSR for the creation of the Ka-25 helicopter. Later on Ka-25 was the basis for development of a multifunctional civil Ka-26 helicopter, and for the Navy – a new antisubmarine Ka-27.

S.H. Shamsutdinov,
Russian State Archive of Scientific and Technical Documentation