Sikorsky H-19

For other uses of "H19" see H19 (disambiguation).

The Sikorsky H-19 Chickasaw, (also known by its Sikorsky model number, S-55) was a multi-purpose helicopter used by the United States Army and United States Air Force. It was also license-built by Westland Aircraft as the Westland Whirlwind in the United Kingdom. United States Navy and United States Coast Guard models were designated HO4S, while those of the U.S. Marine Corps were designated HRS. In 1962, the U.S. Navy, U.S. Coast Guard and U.S. Marine Corps versions were all redesignated as H-19s like their U.S. Army and U.S. Air Force counterparts.

Design and development
The H-19's first flight was on 10 November 1949 and it entered operations in 1950. Over 1,000 of the helicopters were manufactured by Sikorsky for the United States. An additional 550 were manufactured by licensees of the helicopter including Westland Aircraft, the SNCASE in France and Mitsubishi in Japan.

The helicopter was widely exported, used by many other nations, including Portugal, Greece, Israel, Chile, South Africa, Denmark and Turkey.

In 1954 the Marines tested an idea to assist the rotors lift better in hot or high climates and if the helicopter was overloaded, by installing a rocket nozzle at the tip of each rotor blade with the fuel tank located in the center above the rotor blade hub. Enough fuel was provided for seven minutes of operation.

Operational history
The H-19 Chickasaw holds the distinction of being the US Army's first true transport helicopter and, as such, played an important role in the initial formulation of Army doctrine regarding air mobility and the battlefield employment of troop-carrying helicopters. The H-19 underwent live service tests in the hands of the 6th Transportation Company, during the Korean War beginning in 1951 as an unarmed transport helicopter. Undergoing tests such as medical evacuation, tactical control and front-line cargo support, the helicopter succeeded admirably in surpassing the capabilities of the H-5 Dragonfly which had been used throughout the war by the Army.

The U.S. Air Force ordered 50 H-19A's for rescue duties in 1951. These aircraft were the primary rescue and medical evacuation helicopters for the USAF during the Korean War. The Air Force continued to use the H-19 through the 1960s, ultimately acquiring 270 of the H-19B model.

France made aggressive use of helicopters in Algeria, both as troop transports and gunships, Piasecki/Vertol H-21 and Sud-built Sikorski H-34 helicopters rapidly displaced fixed-wing aircraft for the transport of paras and quick-reaction commando teams. In Indochina, a small number of Hiller H-23s and Sikorsky H-19s were available for casualty evacuation. In 1956, the French Air Force experimented with arming the H-19, then being superseded in service by the more capable Piasecki H-21 and Sikorsky H-34 helicopters. The H-19 was originally fitted with a 20-mm cannon, two rocket launchers, plus a 20-mm cannon, two 12.7-mm machine guns, and a 7.5-mm light machine gun firing from the cabin windows, but this load proved far too heavy, and even lightly armed H-19 gunships fitted with flexible machine guns for self-defense proved underpowered.

The H-19 was also used in the early days of the Vietnam War before being supplanted by the Sikorsky H-34 Choctaw, which was based on the H-19.

Variants
Later marks of Whirlwind were built under licence.
 * YH-19: Five early production S-55s for evaluation.
 * H-19A: USAF version of the YH-19 powered by a 600 hp, (472 kW) R-1340-57 engine, redeisgnated UH-19A in 1962, 50 built.
 * SH-19A: H-19As modified for air-sea rescue, redesignated HH-19A in 1962.
 * H-19B: H-19A with a more powerful 700 hp, (522 kW) R-1300-3 engine, redesignated UH-19B in 1962, 264 built.
 * SH-19B: H-19Bs modified for air-sea rescue, redesignated HH-19B in 1962.
 * H-19C: US Army version of the H-19A, redesignated UH-19C in 1962, 72 built.
 * H-19D: US Army version of the H-19B, redesignated UH-19D in 1962, 301 built.
 * HO4S-1: US Navy version of the H-19A, 10 built.
 * HO4S-2: Project for rescue version for the United States Coast Guard, not built.
 * HO4S-3: Re-engined US Navy & Canadian version with 700 hp, (522 kW) Wright R-1300 engine, redesignated UH-19F (American variant) H04S-3 (Canadian variant) in 1962, 79 built.
 * HO4S-3G: United States Coast Guard version of the HO4S-3, redesignated HH-19G in 1962, 30 built.
 * HRS-1: United States Marine Corps version of the HO4S for eight troops, 60 built.
 * HRS-2: HRS-1 with equipment changes, 101 built.
 * HRS-3: HRS-2 with a 700 hp, (522 kW) R-1300-3 engine, became CH-19E in 1962, 105 built and conversions from HRS-2.
 * HRS-4: Project for HRS-3 with a 1,025 hp, (764 kW) R-1820 radial engine, not built.
 * UH-19A: H-19A redesignated in 1962.
 * HH-19A: SH-19A redesignated in 1962.
 * UH-19B: H-19B redesignated in 1962.
 * HH-19B: SH-19B redesignated in 1962.
 * CH-19E: HRS-3 redesignated in 1962.
 * UH-19F: HO4S-3 redesignated in 1962.
 * HH-19G: HO4S-3G redesignated in 1962
 * S-55: Commercial version with 600 hp, (472 kW) R-1340 engine.
 * S-55A: Commercial version with 800 hp, (596 kW) R-1300-3 engine.
 * S-55C: S-55A with a 600 hp, (472 kW) R-1340 engine.
 * S-55T: aircraft modified by Aviation Specialties and produced and marketed by Helitec with a 650 shp, (485 kW) Garrett AiResearch TPE-331-3U-303 turboshaft and updated equipment.
 * S-55QT: Commercial conversion. Ultra-quiet helicopter for sight-seeing flights over the Grand Canyon.
 * OHA-S-55 Heli-Camper: Commercial conversions carried out by Orlando Helicopters.
 * OHA-S-55 Nite-Writer: Commercial conversion. Aerial advertising helicopter, fitted with a 12.2-m x (40-ft x 8-ft) array of computer-controlled lights.
 * OHA-S-55 Bearcat: Commercial conversion. Agricultural helicopter.
 * OHA-S-55 Heavy Lift: Commercial conversion. Flying crane helicopter.
 * QS-55 Aggressors: Commercial conversion. S-55 helicopters converted into flying targets.
 * OHA-AT-55 Defender: Commercial conversion. Armed military helicopter.
 * Whirlwind HAR21: HRS-2 for Royal Navy, ten delivered.
 * Whirlwind HAS22: H04S-3 for Royal Navy, 15 delivered.

Aircraft on display

 * Fantasy of Flight, Polk City, Florida: S-55 registered as N111VA
 * National Museum of Naval Aviation, NAS Pensacola, Florida: HH-19G, Coast Guard Ser. No. 1258 is displayed in US Coast Guard colors
 * Flying Leatherneck Aviation Museum, MCAS Miramar, San Diego, California: HRS-3 "Chickasaw" of HMR-161, United States Marine Corps – BuNo. 130252
 * National Museum of the United States Air Force, Wright-Patterson AFB, Ohio: UH-19B AF Ser. No. 52-7587 is painted in the colors of one of the helicopters to make the first trans-Atlantic flight
 * Orlando Sanford International Airport UH-19D c/n 55-3197 is in civilian colors (registered as N95487)
 * Smithsonian National Air and Space Museum The first S-55/YH-19 is on display at the Udvar-Hazy Center
 * Pima Air and Space Museum, adjacent to Davis-Monthan AFB, Arizona: UH-19B, AF Ser. No. 52-7537 and civilian registered as N2256G is painted in USAF rescue colors
 * Valiant Air Command Warbird Museum, Space Coast Regional Airport, Florida: UH-19D, AF Ser. No. 57-5937 and civilian registered as N37788 is painted in USAF rescue colors
 * Evergreen Aviation & Space Museum, adjacent to McMinnville Municipal Airport in McMinnville, Oregon: H-19A Army Ser. No. 52-7602 is displayed indoors in U.S. Army colors.
 * Danmarks Flymuseum, Stauning, Denmark: Danish Air Force S-55C S-884.
 * Norwegian Armed Forces Aircraft Collection, Gardermoen, Norway: RNoAF H-19D-4, Ser. No. 56-4279.
 * Strategic Air and Space Museum in Ashland, NE, located near Offutt AFB. Ser. No. 53-4426
 * See Westland Whirlwind (helicopter) for examples of the S55 preserved in UK and elsewhere