The Sikorsky S-58 was developed as essentially a lengthened and more powerful version of the Sikorsky (model S-55) or UH-19 Chickasaw, with a similar nose, but with a tail-dragger rear fuselage and landing gear rather than the high-tail 4 post pattern. It retained the nose-mounted piston engine with the drive shaft passing the cockpit placed high above the cargo compartment.
The aircraft first flew on 8 March 1954. The first production aircraft was ready in September and entered in service for the United States Navy initially designated HSS-1 Seabat (in its anti-submarine configuration) and HUS-1 Seahorse (in its utility transport configuration) under the U.S. Navy designation system for U.S. Navy, United States Marine Corps (USMC) and United States Coast Guard (USCG) aircraft. The U.S. Army and Marine Corps, respectively, ordered it in 1955 and 1957. Under the United States Army’s aircraft designation system, also used by the United States Air Force, the helicopter was designated H-34. The U.S. Army also applied the name Choctaw to the helicopter. In 1962, under the new unified DoD aircraft designation system, the Seabat was redesignated SH-34, the Seahorse as the UH-34, and the Choctaw as the CH-34.
Roles included utility transport, anti-submarine warfare, search and rescue, and VIP transport. In it standard configuration transport versions could carry 12 to 16 troops, or eight stretcher cases if utilized in the MedEvac role, while VIP transports carried significantly fewer people in significantly greater comfort.
A total of 135 H-34s were built in the U.S. and assembled by Sud-Aviation in France, 166 were produced under licence in France by Sud-Aviation for the French Air Force, Navy and Army Aviation (ALAT).
The CH-34 was also built and developed under license from 1958 in the United Kingdom by Westland Aircraft as the turbine engined Wessex which was used by the Royal Navy and Royal Air Force. The RN Wessex was fitted out with weapons and ASW equipment for use in an antisubmarine role. The RAF used the Wessex, with turboshaft engines, as an air/sea rescue helicopter and as troop transporter. Wessexes were also exported to other countries and produced for civilian use.
French evaluations on the reported ground fire vulnerabilities of the CH-34 may have influenced the U.S. Army’s decision to deploy the CH-21 Shawnee to Vietnam instead of the CH-34, pending the introduction into widespread service of the Bell UH-1 Iroquois. U.S. Army H-34s did not participate in Vietnam, and did not fly in the assault helicopter role, however a quantity were supplied to the Army of the Republic of Vietnam. These saw little use due lack of spare parts and maintenance.
The USMC continued to use the H-34 pattern, even after the U.S. Army had phased it out. Even after the USMC adopted their own version of the UH-1, the UH-1E, the CH-34s continued to be used up to and for a period after the Tet Offensive in 1968. They were often armed, with a machine gun on a flexible door mount or window mount, initially a Browning 7.62 millimeter later replaced by the lighter 7.62 millimeter M60. Armor was also eventually added to protect the engine and crew.
Its higher availability and reliability due to its simplicity compared to the newer helicopters led Marines to ask for it by name. The phrases “give me a HUS”, “get me a HUS” and “cut me a HUS” entered the USMC vernacular, being used even after the type was no longer in use to mean “help me out”.
USMC H-34s were also among the first gunship helicopters trialled in theatre, being fitted with the Temporary Kit-1 (TK-1), comprising two M60C machine guns and two 19 shot 2.75 inch rocket pods. The operations were met with mixed enthusiasm, and the armed H-34s, known as “Stingers” were quickly phased out. The TK-1 kit would form the basis of the TK-2 kit used on the UH-1E helicopters of the USMC.
On August 18, 1969, the last Marine UH-34D in Vietnam was retired from HMM-362 at Phu Bai. During that period, enemy action and accidents downed 134 helicopters. Most of the twenty surviving CH-34 helicopters were turned over to the South Vietnamese during the course of the war, though a few were ultimately reclaimed by the Army prior to the final collapse of the Saigon Government.
The H-34 remained in service with United States Army and Marine Corps aviation units well into the late 1960s, and was standard equipment in Marine Corps Reserve, Army Reserve and Army National Guard aviation units until replaced by the UH-1 Iroquois utility helicopter. Sikorsky production ceased in 1968, with 1,821 built. On 3 September 1973, the last flight of a USMC UH-34 occurred as bureau number 147191 was flown to MCAS New River. All H-34 helicopters were retired from service in the U.S. military by the early 1970s.
The Sikorsky H-34 Choctaw (Company designation S-58) was a piston-engined military helicopter originally designed by American aircraft manufacturer Sikorsky for the United States Navy for service in the anti-submarine warfare (ASW) role.
Sikorsky H-34s have since served mostly as medium transports on every continent with the armed forces of twenty-five countries — from combat in Algeria, the Dominican Republic, Nicaragua, and throughout Southeast Asia, to saving flood victims, recovering astronauts, fighting fires, and carrying presidents. As one of the last piston-powered helicopter designs before its replacement by turbine-powered types such as the UH-1 Huey and CH-46 Sea Knight, it would see a remarkably long run of 2,108 H-34s produced between 1953 and 1970. It would see extended use when adapted to turbine power by the British licencee as the Westland Wessex and Sikorsky as the later S-58T. The British did not retire the Wessex until 2003 as the main transport helicopter; it was replaced by the Aérospatiale Puma.
|Capacity:||16 troops or 8 stretchers|
|Length:||56 ft 8.5 in (17.28 m)|
|Rotor diameter:||56 ft 0 in (17.07 m)|
|Height:||15 ft 11 in (4.85 m)|
|Disc area:||2,463 ft² (228.85 m²)|
|Empty weight:||7,900 lb (3,583 kg)|
|Max. takeoff weight:||14,000 lb (6,350 kg)|
|Powerplant:||1 × Wright R-1820-84 radial engine, 1,525 hp (1,137 kW)|
|Maximum speed:||123 mph (107 kn, 198 km/h)|
|Range:||293 km (182 mi)|
Various (See Main Article: U.S. Helicopter Armament Subsystems)