|Sikorsky H-34 / S-58|
|First flight||8 March 1954|
|Status||out of production, still in civilian service|
|Primary users||United States Army|
United States Navy
United States Marines
|Developed from||H-19 Chickasaw|
The Sikorsky H-34 Choctaw (company designation S-58) is a piston-engined military helicopter that was originally designed by American aircraft manufacturer Sikorsky for the United States Navy for service in the anti-submarine warfare (ASW) role. It has seen extended use when adapted to turbine power by the British licensee as the Westland Wessex and Sikorsky as the later S-58T. Various H-34s 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, in roles such as 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.
The Sikorsky S-58 was developed as 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 through 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 to a lack of spare parts and maintenance.
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 U.S. Marine Corps 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.
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.
France bought 134 Choctaws in parts from the United States and assembled by Sud-Aviation. A further 166 were manufactured later locally for the French Army, Navy and Air force, these again produced by Sud-Aviation.
The H-34 was the primary VNAF helicopter until replaced by the Bell UH-1 Huey.
The S-58 flew combat missions after the end of the Six Days War, mainly against Palestinians infiltrating Israel or against their bases in Jordan. On 21 March 1968, they participated in the Battle of Karameh, bringing Israeli troops in and out as well as evacuating the wounded. This was the last operation of the S-58 as it was retired shortly later, replaced by the Bell 205 and Aérospatiale Super Frelon.
- The H-34's lift capacity was just sufficient to lift a Mercury space capsule. In 1961, the hatch of Mercury-Redstone 4 was prematurely detached and the capsule was filled with seawater. The extra weight was too much for the H-34 and the capsule, Liberty Bell 7, was emergency released and sank in deep water.
- In the 1990s, an S-58ET called Miss Piggy from "New York Helicopter" flew passengers from JFK International Airport to East 34th Street Heliport, New York.
- H-34 have been used by forest firefighting contractors in Ontario.
- At least one S-58 was purchased for civilian use by Oregon-based Columbia Helicopters in the 1960s.
- In 1968, an S-58 was used to remove the wreckage of a Bell 47 G2 helicopter from the top of Uluru (Ayers Rock) in central Australia.
- The 1980s television series Riptide featured an S-58T called "The Screaming Mimi". The special turbine engine cowling, together with a "face" paint scheme was used to good effect.
- U.S. Army version of the HSS-1 powered by a 1,525 hp R-1820-84, re-designated CH-34A in 1962, 359 built and 21 transferred from the U.S. Navy.
- Designation for H-34A used for weapon tests.
- Staff transport conversions of H-34A.
- H-34As converted with detail changes, became CH-34B in 1962.
- H-34B design with detail changes converted from H-34As, became CH-34C in 1962.
- Designation for CH-34C used for weapon tests.
- Staff transport conversions of CH-34C.
- Designation applied to aircraft given USAF serials to be transferred under MAP and MDAP.
- HUS-1L re-designated in 1962
- HUS-1 re-designated in 1962 and 54 new build.
- HUS-1Z re-designated in 1962
- HUS-1A re-designated in 1962
- HUS-1G re-designated in 1962
- YHSS-1 re-designated in 1962
- HSS-1 re-designated in 1962
- HSS-1F re-designated in 1962
- YHSS-1N re-designated in 1962
- HSS-1N re-designated in 1962
- SH-34J without ASW equipment for cargo and training purposes.
- Ex-USN UH-34Js operated by the U.S. Air Force
- Staff transport conversions of SH-34J.
- XHSS-1 Seabat
- Three Sikorsky S-58s for evaluation by the U.S. Navy, re-designated YHSS-1 then YSH-34G in 1962.
- HSS-1 Seabat
- Production Anti-Submarine model for the U.S. Navy, re-designated SH-34G in 1962, 215 built
- HSS-1F Seabat
- One HSS-1 re-engined with two YT-58-GE as a flying test bed, re-designated SH-34H in 1962.
- YHSS-1N Seabat
- One HSS-1 converted as the HSS-1N prototype, re-designated YSH-34J in 1962.
- HSS-1N Seabat
- Night/Bad weather version of the HSS-1 with improved avionics and autopilot, re-designated SH-34J in 1962, 167 built (an addition 75 HSS-1 airframes were built to CH-34C standard for West Germany).
- HUS-1 Seahorse
- Utility transport version of the HSS-1 for the U.S. Marine Corps, re-designated UH-34D in 1962, 462 built
- HUS-1A Seahorse
- Forty HUS-1s fitted with amphibious pontoons, re-designated UH-34E in 1962.
- HUS-1G Seahorse
- United States Coast Guard version of the HUS-1, re-designated HH-34F in 1962, six built.
- HUS-1L Seahorse
- Four HUS-1s converted for antarctic operations with VXE-6, re-designated LH-34D in 1962.
- HUS-1Z Seahorse
- Seven HUS-1s fitted with VIP interior for the Executive Flight Detachment, re-designated VH-34D in 1962.
- Commercial designation for basic cargo variant
- Commercial designation for improved cargo variant
- Commercial passenger transport/airliner version
- Commercial airliner/freighter version
- Commercial conversion to turboshaft power by Sikorsky, Orlando Helicopter, and California Helicopter. Kit uses Pratt & Whitney Canada PT6T-3 Twin-Pac turboshaft with special nose cowling featuring distinctive twin rectangular air intakes.
- S-58 Heli-Camper
- Commercial conversion, fitted with a Wright Cyclone R-1820-24 engine.
- Orlando Airliner
- Commercial conversion. 18-seat passenger transport helicopter.
- Westland Wessex
- Licence production and development in the United Kingdom.
- United States Air Force
- United States Army
- United States Marine Corps
- United States Navy 
- United States Coast Guard
Accidents and incidents
- 27 July 1960 Chicago Helicopter Airways Flight 698 a S-58C registered N879 crashed into Forest Home Cemetery, Forest Park, Illinois, United States with the loss of 11 passengers and two crew. The investigation concluded that the helicopter became uncontrollable as a result of structural disintegration in flight caused by a fatigue failure of the main rotor blade.
- 13 March 2011 Sikorsky S-58ET, N33602, suffered an engine failure, descended and veered off the side of an office building in El Segundo, California, while lifting an external load from the roof. The commercial pilot was seriously injured, the helicopter was substantially damaged and consumed by a post-impact fire. The helicopter was registered to Heli Flight, Inc., and operated by Aris Helicopters.
Aircraft on display
- UH-34D Seahorse on display on the flight deck of the USS Yorktown (CV-10) at the Patriot's Point Naval and Maritime Museum in Charleston, South Carolina.
- S-58T, H4K-64/30 / 20117 (cn 58-1117) at the Royal Thai Air Force Museum, Bangkok, Thailand.
- UH-34D Seahorse (S-58A) 150556 (cn 58-1683) at Royal Thai Air Force Museum, Bangkok, Thailand.
- H-34C Choctaw, s/n 054496, 1954, located at Carolinas Aviation Museum in Charlotte, North Carolina.
- UH-34J Sea Bat BuNo 145694, 1958, at the Wings of Freedom Aviation Museum, Naval Air Station Willow Grove, Willow Grove, Pennsylvania
- UH-34D Seahorse Serial BuNo 15055, 1963, is on display on the hangar deck of the USS Hornet (CV-12) at Alameda, California.
- UH-34D, BuNo 150227, is on display at the National Museum of Naval Aviation at Naval Air Station Pensacola, Florida.
- UH-34D is on display at the Smithsonian National Air and Space Museum's Udvar-Hazy Center.
- LH-34D Seabat (s/n 145717) is on display at the New England Air Museum, Bradley International Airport, Windsor Locks, CT 
- SH-34J Sea Horse, is on display at Pueblo Weisbrod Aircraft Museum, Pueblo, Colorado, next to Pueblo Airport.
Specifications (H-34 Choctaw)
- Crew: 2
- 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)
- Service ceiling: 4,905 ft (1,495 m)
- Sikorsky H-19
- Westland Wessex
- Piasecki PA-97
- Mil Mi-4
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