The Sikorsky H-19 Chickasaw (company 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.
For other uses, see H19 (disambiguation).
Family of utility helicopters
H-19 Chickasaw / S-55
An Army UH-19D Chickasaw
Role
Utility helicopter
Type of aircraft
Manufacturer
Sikorsky
First flight
10 November 1949
Introduction
16 April 1950 (U.S. Air Force)
Retired
26 February 1969 (U.S. Navy)
Primaryusers
United States Army United States Air Force United States Navy United States Coast Guard
Development of the H-19 was initiated privately by Sikorsky without government sponsorship. The helicopter was initially designed as a testbed for several novel design concepts intended to provide greater load-carrying ability in combination with easy maintenance. Under the leadership of designer Edward F. Katzenberger, a mockup was designed and fabricated in less than one year.[1]
The first customer was the United States Air Force, which ordered five YH-19 aircraft for evaluation; the YH-19's first flight was on 10 November 1949, less than a year after the program start date. This was followed by delivery of the first YH-19 to the U.S. Air Force on 16 April 1950 and delivery of the first HO4S-1 helicopter to the U. S. Navy on 31 August 1950. A U.S. Air Force YH-19 was sent to Korea for service trials in March 1951, where it was joined by a second YH-19 in September 1951. On 27 April 1951, the first HRS-1 was delivered to the U.S. Marine Corps, and on 2 May 1951, the first S-55 was delivered to Westland Aircraft.[1]
1,281 of the helicopters were manufactured by Sikorsky in the United States. An additional 447 were manufactured by licensees of the helicopter including Westland Aircraft, the SNCASE in France and Mitsubishi in Japan.[1]
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 enhance lift in hot and high and/or heavily loaded conditions 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.[2] Although tests of the system were considered successful, it was never adopted operationally.[1]
Major innovations implemented on the H-19 were the forward placement of the engine below the crew compartment and in front of the main cabin, the use of offset flapping hinges located nine inches (229mm) from the center of the rotor, and the use of hydraulic servos for the main rotor controls. These features yielded an aircraft that was far more capable in a transport role than previous Sikorsky designs.
The forward engine location placed the main cabin essentially in line with the main rotor's rotational axis and close to the aircraft center of gravity, making it easier to maintain proper weight and balance under differing loading conditions.[1] The impetus for this design choice was the recent rejection of the Sikorsky XHJS by the U.S. Navy in favor of the tandem rotor Piasecki HUP Retriever; the Navy had strongly objected to the necessity to use ballast in the cabin-forward XHJS to maintain proper weight and balance, prompting Sikorsky to seek single-rotor design alternatives that did not require this.[3]
Another benefit of this engine location was ease of maintenance, as the engine could be readily accessed at ground level through dual clamshell-style doors; the entire engine could be changed in only two hours, and the radial engine was oriented backwards relative to a typical airplane installation, allowing more convenient access to engine accessories.[1][note 1]
UH-19B rotor head
The offset flapping hinges and hydraulic servos gave more positive flight control under differing loading conditions, isolated the flight controls from vibration, and lessened control forces; the H-19 could be flown with only two fingers on the cyclic control.[1]
The YH-19 prototypes featured a blunt aft fuselage and a single starboard-mounted horizontal tailplane with a small vertical fin at its outboard end. Initial production models added a large fillet-like fin behind the fuselage and under the tailboom, and the tailplane configuration was changed to an inverted "V" shape.[3]
Early H-19 and HO4S variants were powered by a Pratt & Whitney R-1340-57 radial rated at 600hp (472kW) and used a centrifugal clutch that automatically engaged the main rotor when a preset engine speed was reached. However, the HO4S was deemed underpowered in U.S. Navy service with this powerplant, so the aircraft was re-engined with a 700hp (522kW) Wright R-1300-3 radial which the U.S. Navy found to be adequate in an air-sea rescue role; the H-19B, HO4S-3, HRS-3, and subsequent models would use this powerplant. The R-1300 models also used a single horizontal tailplane in place of the early inverted "V" style, and a new hydro-mechanical clutch gave smoother and more rapid rotor acceleration during clutch engagement and allowed the engine to be started and operated at any speed while disengaged from the transmission and rotors.[1]
Early civilian and military S-55 models offered a folding 400lb (181kg) capacity hoist above the starboard main cabin door, while later models could be equipped with a more capable and reliable 600lb (272kg) capacity unit. Starting with the introduction of the S-55C in October 1956, the tailboom was inclined three degrees downward to provide more main rotor clearance during hard landings; models equipped with the inclined tail also used an 8ft 9 in (2.67 m) tail rotor in place of the earlier 8ft 8 in (2.64 m) unit.[1]
Operational history
This section needs additional citations for verification. (July 2015)
Sikorsky H-19 Chickasaw in Istanbul Aviation Museum (İstanbul Havacılık Müzesi), Istanbul, Turkey, with downward-inclined tailboom typical of later models
The H-19 Chickasaw holds the distinction of being the U.S. 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 frontline 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. Marine Corps made extensive use of the H-19 in the Korean War. It was designated as the HRS in USMC service. Marine Squadron HMR-161 arrived in Korea on September 2, 1951 with 15 HRS-1 helicopters. The new helicopter squadron started operations upon arrival. On September 13, 1951, during Operation Windmill I, HMR-161 transported 18,848 pounds (8.5t) of gear and 74 Marines onto a ridge in the Punchbowl area. A week later HMR-161 shuttled 224 recon company marines and 17,772 pounds (8.1t) of supplies to a remote hilltop in the same area. Their performance continued to improve and in Operation Haylift II on February 23–27, 1953, HMR-161 lifted 1.6million pounds (730t) of cargo to resupply two regiments. Although HMR-161 helicopters were operating in hot landing zones they did not lose any helicopters to enemy fire. HRS-1 helicopters were also used to relocate rocket launcher batteries. Because rockets create much visible dust when fired they make an easy target for enemy artillery. To reduce their exposure, launchers and crews were moved twice a day. Each HRS-1 helicopter carried four rocket launchers and extra rockets as external cargo, with the crew in the cabin. The HRS-1 helicopter proved to be durable and reliable in Korean service. One reportedly flew home after losing 18in (46cm) of main rotor blade to a tree. HMR-161 reported 90% aircraft availability.[4]
Sikorsky UH-19 at the Canadian Museum of Flight in 1988, painted as it would have looked while working on the construction of the Mid-Canada Line. This aircraft has the early-style straight tailboom.
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.[5]
On 1 September 1953, Sabena used the S-55 to inaugurate the first commercial helicopter service in Europe, with routes between Rotterdam and Maastricht in the Netherlands and Cologne and Bonn in Germany.[3]
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, 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.[citation needed]
The H-19 was also used by the French forces in the First Indochina War. A small number of war-worn H-19s were given to the Republic of Vietnam Air Force in 1958, when the French military departed. These saw very limited service in the early days of the Vietnam War, before being supplanted by the more capable Sikorsky H-34 Choctaw.[6]
The H-19 left U.S. military service when the CH-19E was retired by U.S. Navy squadron HC-5 on 26 February 1969. Surplus H-19s were sold on the open market, and civil interest was sufficient that Sikorsky (and later Orlando Helicopter Airways) offered conversion kits allowing a military surplus H-19 to be commercially operated under a standard Federal Aviation Administration type certificate as an S-55B.[note 2]Turboshaft conversions were also offered by aftermarket modification companies.[1]
A novel civil conversion of the H-19 by Orlando Helicopter was the Heli-Camper, a campervan-like conversion—featuring a built-in mini-kitchen and sleeping accommodations for four.[1] In the late 1970s, Orlando participated in a joint effort with popular American recreational vehicle (RV) manufacturer Winnebago Industries to market the aircraft, now renamed the Winnebago Heli-Home. A larger version based on the Sikorsky S-58 was also developed, and optional floats were offered for amphibious operations. The aircraft were featured in several American popular magazines and reportedly drew large crowds at RV shows and dealerships, but their high purchase price together with rising 1970s fuel prices resulted in very limited sales; production is not well documented, but is estimated at only six or seven of the S-55 and S-58 versions combined.[7]
Variants
UH-19B, USAF MuseumA U.S. Navy HO4S stationed at NAF El Centro. Inverted "V" tailplane is typical of early models with R-1340 engine.A USMC HRS-2 of HMR-161 in Korea, 1953An HO4S of the Royal Canadian Navy
YH-19
Five early production S-55s for evaluation.
H-19A
USAF version of the YH-19 powered by a 600hp (472kW) R-1340-57 engine, redesignated 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 700hp (522kW) 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, ten built.
HO4S-2
Air-sea rescue version with R-1340[8] derated to 550hp (410kW), three built for Royal Canadian Navy (RCN), two surviving aircraft subsequently converted to HO4S-3 standard.[9]
HO4S-2G
United States Coast Guard version of HO4S-2, seven built.[8]
HO4S-3
Re-engined US Navy & Canadian version with 700hp (522kW) Wright R-1300-3 engine, US Navy aircraft redesignated UH-19F in 1962 (RCN/CAF aircraft retained HO4S-3 designation[9]), 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, 600hp (472kW) R-1340-57 engine,[1] 60 built.[10]
HRS-2
HRS-1 with equipment changes, 101 built.
HRS-3
HRS-2 with 700hp (522kW) R-1300-3 engine, became CH-19E in 1962, 105 built and conversions from HRS-2.
HRS-4
Project for HRS-3 with a 1,025hp (764kW) 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 600hp (472kW) R-1340 engine.
S-55A
Commercial version with 800hp (596kW) R-1300-3 engine.
S-55B
New designation given to civilian kit conversions of military surplus H-19s with R-1300-3 engine.[1]
S-55C
S-55A with a 600hp (472kW) R-1340 engine.
S-55T
Aircraft modified by Aviation Specialties and produced and marketed by Helitec with a 650 shp (485kW) 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/Winnebago Heli-Home
Commercial conversions carried out by Orlando Helicopters; marketed by Winnebago.[1][7]
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
HO4S-3 for Royal Navy, 15 delivered. Later marks of Whirlwind were built under licence.
VAT Elite
Highly modified S-55 from Vertical Aircraft Technologies Inc., powered by a 522kW (700hp)Garret TSE311 driving a 5-bladed rotor.
17 January 1975 – In what remains the deadliest helicopter accident in Icelandic history, an S-55B crashed in Hvalfjörður, Iceland due to severe winds, killing all five passengers and both crewmembers on board.[11][12]
0371/55-633 – S-55 on display at the Museo de la Aviacion Naval in Bahia Blanca, Buenos Aires.[13]
Guatemala
S-55 on display in the traffic circle at the main gate of Air Force Headquarters, Aeropuerto Internacional La Aurora, Guatemala City.[citation needed]
Canada
55885 – HO4S-3 on static display at the Shearwater Aviation Museum in Shearwater, Nova Scotia. It is painted in Royal Canadian Navy Sqn. No. 7 colors as used by Anti-Submarine Squadron HS-50 and Utility Squadron HU-21.[14]
55822 Sikorsky S-55 Horse (H-19, HO4S) on static display at The Hangar Flight Museum in Calgary, Alberta, was operated by Associated Airways in Canada's North. It is fitted with a 550hp Pratt & Whitney Wasp R-1340-S1H2 engine.[15]
130151 – CH-19E on static display at the National Museum of Naval Aviation in Pensacola, Florida. It is displayed in a US Coast Guard paint scheme.[33][34]
130252 – HRS-3 on static display at the Flying Leatherneck Aviation Museum in San Diego, California. It is painted with the unit markings of HMR-161.[35]
52-7537 – UH-19B on static display at the Pima Air and Space Museum in Tucson, Arizona. It is painted as a rescue helicopter with the 534th Air Defense Group.[38]
The accessories for a radial engine were traditionally located on the side of the engine opposite the crankshaft; in a prop-powered airplane that used the more commonplace tractor configuration, the accessories were typically buried inside a cowling or nacelle, resulting in less convenient access than the reversed orientation used in the H-19.
Military aircraft typically do not receive type certificates and thus cannot lawfully be operated commercially, except in certain special cases, such as a civil transport being adopted for military service without significant modifications.
Citations
Devine, Vinny (November 2012). "S-55/H-19/HO4S/HRS Helicopter". Sikorsky Product History. Igor Sikorsky Historical Archives. Retrieved 7 July 2015.
"Rotary Wing". armyaviationmuseum.org. 29 October 2016.
Harding 1990, p. 231.
Bibliography
Duke, R.A., Helicopter Operations in Algeria [Trans. French], Dept. of the Army (1959)
Elliott, Bryn (January–February 1999). "On the Beat: The First 60 Years of Britain's Air Police". Air Enthusiast (79): 68–75. ISSN0143-5450.
France, Operations Research Group, Report of the Operations Research Mission on H-21 Helicopter Dept. of the Army (1957)
Harding, Stephen. U.S. Army Aircraft Since 1947, Shrewsbury, UK: Airlife Publishing (1990). ISBN1-85310-102-8.
Riley, David, French Helicopter Operations in Algeria, Marine Corps Gazette, February 1958, pp.21–26.
Shrader, Charles R., The First Helicopter War: Logistics and Mobility in Algeria, 1954–1962, Westport, Connecticut: Praeger Publishers (1999)
Sonck, Jean-Pierre (January 2002). "1964: l'ONU au Congo" [The United Nations in the Congo, 1964]. Avions: Toute l'Aéronautique et son histoire (in French) (106): 31–36. ISSN1243-8650.
Sonck, Jean-Pierre (February 2002). "1964: l'ONU au Congo". Avions: Toute l'Aéronautique et son histoire (in French) (107): 33–38. ISSN1243-8650.
Spenser, Jay P., Whirlybirds: A History of the U.S. Helicopter Pioneers, Seattle, Washington: University of Washington Press (1998)
Further reading
Núñez Padin, Jorge Felix; Cicalesi, Juan Carlos (2011). Núñez Padin, Jorge Felix (ed.). Sikorsky S-55/H-19 & S-58/T. Serie en Argentina (in Spanish). Vol.6. Bahía Blanca, Argentina: Fuerzas Aeronavales. ISBN978-987-1682-13-3. Archived from the original on 27 August 2014. Retrieved 24 August 2014.
External links
Wikimedia Commons has media related to Sikorsky S-55.
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