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Wessex

The Westland Wessex is a British turbine-powered version of the Sikorsky S-58 "Choctaw", developed under license by Westland Aircraft (later Westland Helicopters), initially for the Royal Navy, and later for the Royal Air Force (RAF). The Wessex was built at Westland's factory at Yeovil in Somerset.

 

Design and development

An American-built Sikorsky HSS-1 was shipped to Westland in 1956 to act as a pattern aircraft. It was re-engined with a Napier Gazelle turboshaft engine, and first flew in that configuration on 17 May 1957. The first Westland-built Wessex XL727, designated a Wessex HAS.1, first flew on 20 June 1958, and they entered anti-submarine duties in 1961 with the Royal Navy Fleet Air Arm. The Royal Navy's anti-submarine examples (HAS.1, HAS.3) also used the Gazelle engine.

The design was adapted in the early 1960s for the RAF, and later Royal Marines, to become a general-purpose helicopter capable of troop-carrying, air ambulance and ground support roles. In contrast with the HAS.1, it used twin Rolls-Royce Gnome engines. These marks (HC.2, HCC.4, HU.5) had a single large exhaust on each side of the nose, the Gazelle-powered examples having a pair of smaller exhausts on either side.

 

Operational history

The Wessex was first used by the RN, the RAF first used the helicopter in 1962, and did not finally retire until January 2003, being the main transport helicopter until the introduction of the Aérospatiale Puma. The bright yellow RAF machines used for air-sea or mountain rescue duties became especially famous and saved many lives.

The Navy pressed the development of the HAS.1 into the improved HAS.3, coming into service in 1967. It saw embarked service on the County class destroyers. The HAS.3 could be identified by a dorsal radome and strake extending behind the "hump".

Wessex helicopters were also used by the Queen's Flight of the RAF to transport VIPs including members of the British Royal Family, from 1969 to 1998. Those Royal helicopters were designated HCC.4 and were essentially similar to the HC.2 but with an upgraded interior, additional navigation equipment and enhanced maintenance programmes. A later version used by the Royal Marine Commandos was the HU.5.

 

Counter-insurgency operations

A crisis arose in 1962 as Brunei was not included in the newly formed Federation of Malaya and Indonesia threatened confrontation, including a continuation of the effort started by the North Kalimantan Liberation Army. By February 1964, RAF and Royal Navy Helicopters including some Westland Wessex operating from bases in Sarawak and Sabah to assist Army and Marine detachments fighting guerilla forces infiltrated by Indonesia over its one thousand mile frontier with Malaysia. In Borneo, the helicopter played a major role in fortifying the frontier and maintaining the frontier strong points by airlifting supplies in. The last Wessex HU MK5 in Borneo were operated by 845 Naval Air Commando Squadron (NACS) "B Flight" in Bario and Sepulot and were withdrawn in early October 1966 to Labuan and were embarked on HMS Bulwark en route to Australia.[citation needed]

Wessex were also used in Oman to support British operations in Dhofar. Three of them transported SAS reinforcements in the Battle of Mirbat.

 

General characteristics

Crew: Two pilots (civilian type 60 Wessex cleared for single pilot operation)

Capacity: 16 troops or 8 stretchers

Length: 65 ft 10 in (20.07 m)

Rotor diameter: 56 ft 0 in (17.07 m)

Height: 15 ft 10 in (4.83 m)

Disc area: 2,463 ft² (229 m²)

Empty weight: 8,340 lb (3,767 kg)

Loaded weight: 13,500 lb (6,136 kg)

Powerplant: 2 × Rolls-Royce Gnome H.1200 Mk.110/111 turboshaft, 1,350 shp (1,007 kW) (limited to 1,550 shp (1,156 kW) total) each

 

Performance

Maximum speed: 132 mph (115 knots, 213 km/h)

Cruise speed: 122 mph (106 knots, 196 km/h)

Range: 310 mi (270 nmi, 499 km) with standard fuel

Service ceiling: 12,000 ft (3,660 m)

Rate of climb: 1,650 ft/min (8.4 m/s)