The Kamov Ka-27 Helix naval helicopter was developed as a direct successor to the aging Kamov Ka-25 line in service with the Soviet Navy - both were primarily used to fulfill the Anti-Ship (AS) role but were eventually branched out to undertake other roles as needed including Search and Rescue (SAR), Anti-Submarine Warfare (ASW), and general over-water transport to serve Soviet Navy ships. As seen in previous Kamov helicopter designs, the Ka-27 did not showcase a conventional tail rotor but was instead driven through two counter-rotating, three-bladed main rotors, one seated atop the other - this action counteracted the torque generated by one rotor assembly over the other.
The Ka-27 shares the same overall dimensions as its Ka-25 predecessor which means that very little in the way of onboard ship storage was revised to accommodate the Ka-27 upon acceptance into the Soviet Navy role. The Helix was crewed by three standard operating personnel that included the pilot, a "tactical coordinator", and an Anti-Surface Weapons Coordinator. There was also seating for up to sixteen passengers which lent the Ka-27 Helix well for the transport role when the interior is equipped as such (Ka-29TB).
The Ka-27 saw a first flight on December 24th, 1973 and was formally introduced during 1982 and some 267 examples were ultimately realized. These went on to serve both Soviet and Russian navies as well as the Ukrainian and Indian navies overseas. One of the Ka-27s offshoots became the modern Ka-31 which arrived in 1995 and serves in the Airborne Early Warning (AEW) role.
Variants of the Ka-27 were led by the Ka-25-2 prototype. The Ka-27K served as the ASW prototype which produced the Ka-27PL ("Helix-A") ASW production model. The Ka-27PS ("Helix-D") became a dedicated SAR model and the Ka-27PV was its armed form. The PL was exported as the Ka-28. The Ka-29TB was developed as an assault transport with seating for sixteen passengers. A civilian market form became the Ka-32 and various sub-variants of this mark were later released.
Military operators (beyond the Soviet Union/Russia) of the Ka-27 have gone on to include Algeria, China, India, Portugal, Syria, Ukraine, Vietnam, South Korea, and the former Yugoslavia. Civilian operators have been recognized in Brazil, Canada, Switzerland, Japan, and Portugal.
The base Ka-27 is powered by 2 x Isotov TV3-117V turboshaft engines delivering 2,230 horsepower each. Performance includes a maximum speed of 170 miles per hour, a cruising speed in the 130 mph range, a service range of 610 miles, and a service ceiling of up to 16,400 feet.
Typical armament has been 1 x torpedo while the helicopter can also dispense depth charges and sonobouys as required.