Sikorsky H-19 Chickasaw

{{Short description|Family of utility helicopters}} {{Other uses|H19 (disambiguation)}} {{Use dmy dates|date=December 2022}} {{Use American English|date=December 2022}}  {{Infobox aircraft |name = H-19 Chickasaw / S-55 |image = File:Sikorsky S-55 inflight (altered).jpg |caption = An Army UH-19D Chickasaw |type = [[Utility helicopter]] |manufacturer = [[Sikorsky Aircraft]] |designer = |first_flight = 10 November 1949 |introduction = 16 April 1950 (U.S. Air Force) |retired = 26 February 1969 (U.S. Navy) |status = |primary_user = [[United States Army]]  |more_users = [[United States Air Force]]<br/>[[United States Navy]]<br/>[[United States Coast Guard]]  |produced =  |number_built = 1,728<ref name=archives>{{cite web|title= S-55/H-19/HO4S/HRS Helicopter |last1= Devine |first1= Vinny |url= http://www.sikorskyarchives.com/S-55.php |date= November 2012 |website= Sikorsky Product History |publisher= Igor Sikorsky Historical Archives |access-date= 7 July 2015}}</ref> |variants = [[Westland Whirlwind (helicopter)|Westland Whirlwind]] |developed_into= [[Sikorsky H-34]] (S-58 / Wessex) }}

The '''Sikorsky H-19 Chickasaw''' (company model number '''S-55''') is a multi-purpose piston-engined [[helicopter]] that was used by the [[United States Army]] and [[United States Air Force]]. It was also license-built by [[Westland Aircraft]] as the [[Westland Whirlwind (helicopter)|Westland Whirlwind]] in the United Kingdom. [[United States Navy]] and [[United States Coast Guard]] models were designated '''HO4S''', while those of the [[United States Marine Corps|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.

The H-19 pioneered the use of a nose-mounted [[radial engine]] powering a single [[Helicopter rotor#Fully articulated|fully articulated]] main rotor located above the cabin, which helped maintain a proper [[Center of gravity of an aircraft|center of gravity]] under varying loading conditions without requiring ballast to maintain [[longitudinal stability]] as with prior Sikorsky designs. This layout gave the H-19 series a characteristic bulbous-nosed appearance and made it one of the first truly successful single-rotor [[utility helicopter]]s, leading to a number of derivative designs including the [[Sikorsky H-34]], which was produced in even greater numbers. The H-19 had a long military career worldwide in the late 20th century, and proved popular with civil operators.

==Development== [[File:Sikorsky HRS-1 130252 HMR-161 (15542730881).jpg|thumb|left|HRS-1 of the USMC, on display at a museum, 2014]] 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.<ref name=archives/>

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 [[Korean War|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.<ref name=archives/>

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, [[SNCASE]] in France and [[Mitsubishi]] in Japan.<ref name=archives/>

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

In 1954 the [[U.S. Marine Corps]] tested an idea to enhance lift in [[hot and high|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.<ref>[https://books.google.com/books?id=sdwDAAAAMBAJ&dq=1954+Popular+Mechanics+January&pg=PA97 "Helicopter Gets Power Boost from Rockets."] ''Popular Mechanics'', November 1954, p. 94.</ref> Although tests of the system were considered successful, it was never adopted operationally.<ref name=archives/>

==Design== [[File:Front three-quarter view of the Sikorsky H-19 Chickasaw at the National Museum of the Air Force near Dayton Ohio.jpg|thumb|Front three-quarter view of the Sikorsky H-19B Chickasaw helicopter at the [[National Museum of the United States Air Force]] showing the engine]] 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 [[Helicopter rotor#Fully articulated|flapping hinges]] located {{convert|9|in|spell=in}} from the center of the rotor, and the use of [[Aircraft flight control system#Hydro-mechanical|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 [[Center of gravity of an aircraft|aircraft center of gravity]], making it easier to maintain [[Center of gravity of an aircraft#Incorrect weight and balance in helicopters|proper weight and balance]] under differing loading conditions.<ref name=archives/> 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.<ref name=heli-archives>{{cite web |title= Sikorsky S-55/H-19 – History and technical description |last1= Bazzani |first1= Mario |url= http://www.heli-archive.ch/en/helicopters/in-depth-articles/sikorsky-s-55h-19/ |date= October 2011 |website= heli-archive |access-date= 10 July 2015 |archive-date= 10 July 2015 |archive-url= https://web.archive.org/web/20150710103910/http://www.heli-archive.ch/en/helicopters/in-depth-articles/sikorsky-s-55h-19/ |url-status= dead }}</ref>

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.<ref name=archives/><ref group=note>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.</ref>

[[File:Milestones-h19-070919-03-16.jpg|thumb|right|UH-19B rotor head, with main rotors folded]] 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 [[Helicopter flight controls#Cyclic|cyclic control]].<ref name=archives/>

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.<ref name=heli-archives/>

Early H-19 and HO4S variants were powered by a [[Pratt & Whitney R-1340|Pratt & Whitney R-1340-57]] radial rated at {{Cvt|600|hp}} 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 {{Cvt|700|hp}} [[Wright R-1300|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 (mechanics)|transmission]] and rotors.<ref name=archives/>

Early civilian and military S-55 models offered a folding {{convert|400|lb|adj=on}} capacity [[hoist (device)|hoist]] above the starboard main cabin door, while later models could be equipped with a more capable and reliable {{convert|600|lb|adj=on}} 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 {{convert|8|ft|9|in|adj=on}} [[tail rotor]] in place of the earlier {{convert|8|ft|8|in|adj=on}} unit.<ref name=archives/>

==Operational history== {{More citations needed section|date=July 2015}} [[File:İstanbul 5411.jpg|thumb|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 (USMC) 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 2 September 1951 with 15 HRS-1 helicopters. The new helicopter squadron started operations upon arrival. On 13 September 1951, during Operation Windmill I, HMR-161 transported {{convert|18848|lb|t|1}} of gear and 74 Marines onto a ridge in the [[Punchbowl (Korean War)|Punchbowl]] area. A week later HMR-161 shuttled 224 recon company marines and {{convert|17772|lb|t|1}} of supplies to a remote hilltop in the same area. Their performance continued to improve and in Operation Haylift II on 23–27 February 1953, HMR-161 lifted {{convert|1.6|e6lb|t}} of cargo to resupply two regiments. Although HMR-161 helicopters were operating in "hot" landing zones near enemy troops, they did not lose any helicopters to enemy fire. HRS-1 helicopters were also used to relocate rocket launcher batteries; the rockets created a dust cloud when fired, making the launcher a target for [[counter-battery fire]], so 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 {{cvt|18|in|cm|0}} of main rotor blade to a tree. HMR-161 reported 90% aircraft availability.<ref>{{cite web|url=http://www.sikorskyarchives.com/S-55.php|title=Sikorsky Archives – S-55|website=sikorskyarchives.com|access-date=13 January 2018}}</ref>

The success of helicopter operations with the USMC prompted the service to seek a [[military light utility vehicle]] that the HRS could lift, leading to the development of the aluminum-bodied, {{cvt|1,700|lb}} [[M422 Mighty Mite]] in the early 1950s. However, developmental issues delayed deployment of the M422 until 1959, by which time the HRS was being replaced by utility helicopters capable of lifting standard U.S. light utility vehicles, rendering the M422 unnecessary and{{snd}}due to its unique design{{snd}}a [[supply chain]] liability. The Mighty Mite was only produced in small numbers and was mostly withdrawn from service by the late 1960s.<ref>{{cite web |last=Allen |first=Jim |title=Backward Glances: 1960 AMC M-422 Mighty Mite |url= https://www.motortrend.com/features/1804-backward-glances-1960-amc-m-422-mighty-mite/ |work=Motor Trend |date=16 April 2018 |access-date=13 September 2024}}</ref>

The U.S. Air Force (USAF) 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.<ref name=NMUSAF>[https://www.nationalmuseum.af.mil/Visit/Museum-Exhibits/Fact-Sheets/Display/Article/196103/sikorsky-uh-19b-chickasaw/ "Sikorsky UH-19B Chickasaw."] ''National Museum of the US Air Force.'' Retrieved: 13 September 2015.</ref>

[[File:Sikorsky_S-55_rescue_hover_bw.jpg|thumb|left|USAF HH-19 in a publicity photo purported to show the rescue of U.S. [[North American F-86 Sabre|F-86]] ace [[Joseph C. McConnell]]; the actual rescue was conducted using a different H-19.<ref name=Werrell/>]]

A notable rescue involving a USAF H-19 occurred on 12 April 1953 when a [[North American F-86 Sabre]] flown by leading American [[flying ace]] [[Joseph C. McConnell]] was riddled with cannon fire from an enemy [[MiG-15]] during a patrol over [[MiG Alley]]. McConnell was able to turn and shoot down the attacking MiG, but his F-86 was badly damaged and began losing engine power. Realizing he could not make it back to base, McConnell headed for the USAF rescue base at [[Chodo Airport|Cho-do]], spotting an H-19 below him. H-19 pilots Joe Sullivan and Don Crabb, alerted that two damaged Sabres were headed towards them, saw McConnell's F-86 and changed course to parallel it. McConnell [[ejection seat|ejected]] over the [[Yellow Sea]] near the helicopter and was pulled from the water within two minutes by H-19 medic Arthur Gillespie; McConnell later told his sister "I barely got wet." Seeking favorable publicity for its ace pilots in Korea, the USAF circulated a rescue photo which was widely published in U.S. newspapers; however, Sullivan, Crabb, and Gillespie were flying a different H-19 without rescue markings that day. Historian Kenneth P. Werrell writes that the misleading, staged photo was likely a ruse to conceal the fact that the H-19 was not originally on an air rescue mission but was instead supporting [[special operations]] in the Cho-do area.<ref name=Werrell> {{cite book | last = Werrell | first = Kenneth P. | date = 2005 | title = Sabres over MiG Alley: The F-86 and the Battle for Air Superiority over Korea | location = Annapolis, Maryland | publisher = Naval Institute Press | pages = 115–116 | isbn = 1-59114-933-9 }}</ref>

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 [[West Germany]].<ref name=heli-archives/>

France made aggressive use of helicopters in Algeria, both as troop transports and gunships. [[Piasecki H-21]] and [[Sud Aviation|Sud]]-built [[Sikorsky 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-23]]s and 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 H-21 and H-34. The H-19 was originally fitted with a 20mm cannon, two rocket launchers, two 12.7mm machine guns, and a 7.5mm 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|reason=No source given|date=July 2015}}

[[File:Envol bruyant et poussiéreux de l'hélicoptère du point d'appui de Muong Khoua.jpg|thumb|French Sikorsky H-19 helicopter taking off from a forward operating base during the Indochina war]] 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 H-34.<ref>Mesko, Jim. ''Airmobile: The Helicopter War in Vietnam'', pages 4-6. Carrollton, Texas: Squadron/Signal Publications, 1984. {{ISBN|0-89747-159-8}}</ref>

Pakistan ordered eight S-55s in 1956 to equip [[search and rescue]] squadrons of the [[Pakistan Air Force]]. They saw service during the [[1965 Indo-Pakistani War]], flying various missions including [[counterintelligence]] operations at Karachi in co-operation with the [[Pakistan Army|Army]]. They were retired from service in 1971.<ref>{{Cite web |url=https://armstransfers.sipri.org/ArmsTransfer/TransferRegister |title=Arms transfers database |website=[[Stockholm International Peace Research Institute]]}}</ref><ref>{{Cite book |title=Battle for Pakistan |last=Fricker |first=John |publisher=[[Ian Allan Publishing]] |year=1979 |isbn=0711009295 }}</ref><ref>{{Cite book |title=History of the Pakistan Air Force, 1947-1982 |last1=Hussain |first1=Shabbbir |year=1982|url=https://opac.nlp.gov.pk/index.php?p=show_detail&id=142534&keywords= |last2=Quraishi |first2=Tariq}}</ref>

The H-19 left U.S. military service when the CH-19E was retired by U.S. Navy squadron [[HSC-25|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]] or OHA) 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.<ref group=note>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.</ref> [[Turboshaft]] conversions were also offered by aftermarket modification companies.<ref name=archives/>

[[File:S-55MidCanadaLine.JPG|thumb|right|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.]]

A novel civil conversion of the H-19 by OHA was the '''Heli-Camper''', a [[campervan]]-like conversion—featuring a built-in mini-kitchen and sleeping accommodations for four.<ref name=archives/> In the late 1970s, OHA 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 aircraft|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.<ref name=Winnebago>{{cite web|url=https://www.smithsonianmag.com/air-space-magazine/the-flying-winnebago-3672/ |title=The Flying Winnebago |last=Chiles |first=James R. |work=Air & Space Magazine |date=January 2012 |access-date=28 July 2022}}</ref>

In the mid-1980s, the U.S. Army sought an economical helicopter to simulate the sound and [[radar signature]] of the Soviet [[Mil Mi-24]] during exercises. OHA sold the Army fifteen modified '''S-55/Mi-24'''s with a new five-bladed rotor system, which was quieter than the original three-bladed rotor and made the aircraft sound similar to an Mi-24. The piston engines and original Sikorsky tail rotors were retained.<ref name=QT>{{cite web |url=https://verticalmag.com/features/remaking-a-classic-html/ |title=Remaking a classic |publisher=Vertical Mag |website=verticalmag.com |date=8 April 2011 |last=Robinson |first=Skip |access-date=26 June 2024}}</ref>

OHA also produced the '''S-55QT Whisper Jet''', an extra-quiet civil conversion based on the five-bladed S-55/Mi-24, but using an {{convert|840|hp}} [[Garrett TPE331]] derated to {{convert|650|hp}} from the S-55T, which lowered the aircraft's empty weight by {{convert|900|lb}}. The aircraft were also outfitted with special intake and exhaust silencers, [[carbon fiber]] noise-absorbing engine compartment doors, and a transparent [[Plexiglas]] floor. Five aircraft were built in 1999 to comply with strict [[National Park Service]] noise limits for [[Grand Canyon]] aerial tours; however, the aircraft were only used in this role for two years because it was difficult for pilots in the high-mounted cockpit to communicate with tourists in the main cabin. After being retired from sightseeing, the helicopters were used in utility and lift roles.<ref name=QT/>

===Pre-1962 USAF designations=== ;YH-19 :Five early production S-55s for evaluation ;H-19A :USAF version of the YH-19 powered by a {{Cvt|600|hp}} 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 {{Cvt|700|hp}} [[Wright R-1300|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 :U.S. Army version of the H-19A, redesignated UH-19C in 1962, 72 built. [[File:Sikorsky S-55 inflight c.jpg|thumb|H-19D (S-55) of the U.S. Army]] ;H-19D :U.S. Army version of the H-19B, redesignated UH-19D in 1962, 301 built.

===Pre-1962 US Navy, Marine Corps and Coast Guard designations=== ;HO4S-1 :US Navy version of the H-19A, ten built. ;HO4S-2 :Air-sea rescue version with R-1340<ref name=USCG-2G>{{cite web|title= Sikorsky HO4S-2G / 3G; HH-19G "Chickasaw" |url= http://www.uscg.mil/history/aviation/Sikorsky/Sikorsky_HO4S.pdf |work= U.S. Coast Guard Aviation History |access-date= 30 June 2015 }}</ref> [[derating|derated]] to {{Cvt|550|hp}}, three built for [[Royal Canadian Navy|Royal Canadian Navy (RCN)]], both surviving aircraft subsequently converted to HO4S-3.<ref name=RCN>{{cite web|title= Canada Aviation Museum Aircraft – Sikorsky HO4S-3 (S-55) Horse – Royal Canadian Navy (RCN) |last1= Murray |first1= Robert |url= http://jproc.ca/rrp/rrp3/ho4s3_r_murray.pdf |work= Canada Aviation Museum |access-date= 30 June 2015 }}</ref> ;HO4S-2G :US Coast Guard version of HO4S-2, seven built.<ref name=USCG-2G/> ;HO4S-3 :Re-engined US Navy and RCN air-sea rescue version with {{Cvt|700|hp}} Wright R-1300-3 engine, 79 built. ;HO4S-3G :US Coast Guard version of HO4S-3, 30 built. ;HRS-1 :US Marine Corps version of HO4S for eight troops, {{Cvt|600|hp}} R-1340-57 engine,<ref name=archives/> 60 built.<ref>[https://books.google.com/books?id=ytwDAAAAMBAJ&dq=1954+Popular+Mechanics+January&pg=PA97 "Here Comes the Leathernecks!"] ''Popular Mechanics'', April 1952, p. 97.</ref> ;HRS-2 :HRS-1 with equipment changes, 101 built. ;HRS-3 :HRS-2 with {{Cvt|700|hp}} R-1300-3 engine, 105 built and conversions from HRS-2. ;HRS-4 :Project for HRS-3 with a {{Cvt|1025|hp}} [[R-1820]] radial engine, not built.

===Post-1962 Tri-Service designations=== ;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 :US HO4S-3 redesignated in 1962. (RCN/[[Canadian Armed Forces|CAF]] aircraft retained HO4S-3 designation.)<ref name=RCN/> ;HH-19G :HO4S-3G redesignated in 1962.

===Royal Navy designations=== ;Whirlwind HAR21: HRS-2 for Royal Navy, ten delivered. ;Whirlwind HAS22: HO4S-3 for Royal Navy, 15 delivered. Later marks of [[Westland Whirlwind (helicopter)|Whirlwind]] were built under licence.

===Thai designations=== ;H.3: ({{langx|th|ฮ.๓}}) [[Royal Thai Armed Forces]] designation for the S-55.<ref>{{Cite web |title=Thai Military Aircraft Designations |url=https://designation-systems.net/non-us/thailand.html |access-date=2025-03-20 |website=designation-systems.net}}</ref>

===Civil variants=== ;S-55: Commercial version with {{Cvt|600|hp}} R-1340 engine. ;S-55A: Commercial version with {{Cvt|800|hp}} R-1300-3 engine. ;S-55B: New designation given to civilian kit conversions of military surplus H-19s with R-1300-3 engine.<ref name=archives/> ;S-55C: S-55A with a {{Cvt|600|hp}} R-1340 engine. ;S-55T: Aircraft modified by [[Aviation Specialties]] and produced and marketed by [[Helitec]] with a {{Cvt|650|hp}} [[Garrett AiResearch TPE-331]]-3U-303 turboshaft and updated equipment. ;S-55/Mi-24: Orlando Helicopter Airways (OHA) conversion for U.S. Army to simulate the [[Mil Mi-24]]. Used newly-designed five-bladed rotor assembly with piston engine. Fifteen converted.<ref name=QT/> ;S-55QT: OHA conversion. Ultra-quiet helicopter for sightseeing flights over the Grand Canyon. S-55T with five-bladed rotor from S-55/Mi-24 and additional sound-reducing equipment. Five converted.<ref name=QT/> ;OHA-S-55 Heli-Camper/Winnebago Heli-Home: OHA conversion marketed by Winnebago.<ref name=archives/><ref name=Winnebago/> ;OHA-S-55 Nite-Writer: Commercial conversion. Aerial advertising helicopter, fitted with a 12.2 m × (40 ft × 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. ;VAT Elite: Highly modified S-55 from Vertical Aircraft Technologies Inc., powered by a {{cvt|522|kW}} [[Garret TSE311]] driving a 5-bladed rotor.

==Operators== [[File:H-55 Sikorsky S-55 Chilean Airforce (7322311282).jpg|thumb|S-55 of the Air Force of Chile on display at a museum]] {{Main|List of Sikorsky H-19 operators}}

==Notable accidents== * 17 January 1975 – In what remains the deadliest helicopter accident in Icelandic history, an [[1975 Kjalarnes helicopter crash|S-55B crashed in Hvalfjörður, Iceland]] due to severe winds, killing all five passengers and both crewmembers on board.<ref name="seven">{{cite news |title=Sjö fórust |url=https://timarit.is/page/3259862 |accessdate=8 August 2021 |work=[[Vísir]] |date=17 January 1975 |page=1 |language=Icelandic}}</ref><ref>{{cite news |title=Flugmanni varð ekki á stórkostleg vangá |url=https://timarit.is/page/2473179 |accessdate=8 August 2021 |work=[[Dagblaðið Vísir]] |date=2 March 1983 |page=4 |language=Icelandic}}</ref>

==Aircraft on display== See [[Westland Whirlwind (helicopter)#Surviving aircraft|Westland Whirlwind museum examples]] for examples of the British license-built S-55. [[File:Sikorsky HRS-3 (CH-19E) Chickasaw US Marines 130252 HR1 (7402551900).jpg|thumb|Sikorsky HRS-3, later renamed the CH-19E, of the US Marine Corps at museum]] [[File:Spanish Sikorsky Westland S-55.jpg|thumb|S-55 of Spain]] ;Argentina * H-04 – S-55 on display at the [[Museo Nacional de Aeronáutica de Argentina]] in [[Morón, Buenos Aires]].{{Citation needed|date=March 2016}} * 0371/55-633 – S-55 on display at the Museo de la Aviacion Naval in [[Bahia Blanca|Bahia Blanca, Buenos Aires]].<ref>Padín & Cicalesi (2003), pag.26</ref>

;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|date=June 2019}}

;Canada * 55822 – S-55 on static display at [[The Hangar Flight Museum]] in [[Calgary, Alberta]]. It was operated by Associated Airways in Canada's north and is fitted with a 550 hp Pratt & Whitney Wasp R-1340-S1H2 engine.<ref>{{cite web |title=Sikorsky S-55 Horse (H-19, H04S) |url=http://www.thehangarmuseum.ca/our-collections/sikorsky-s-55-horse-h-19-h04s |website=The Hangar Flight Museum |access-date=17 July 2023}}</ref> * 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.<ref>{{cite web |url=http://www.shearwateraviationmuseum.ns.ca/exhibits/horse.htm |title=Sikorsky HO4S-3 "Horse" |publisher=Shearwater Aviation Museum |access-date=21 October 2014 |archive-date=13 October 2006 |archive-url=https://web.archive.org/web/20061013223845/http://www.shearwateraviationmuseum.ns.ca/exhibits/horse.htm |url-status=dead }}</ref>

;Denmark * S-883 - S-55C C/N 55-1031, on static display at Danmarks Tekniske Museum in [[Helsingør]] * S-884 – S-55C C/N 55-1032, on static display at the [[Danmarks Flymuseum]] in [[Skjern, Denmark|Skjern, Ringkøbing-Skjern]].<ref>{{cite web|url=http://flymuseum.dk/fly?id=225:sikorsky-s-55c&catid=34 |title=Danmarks Flymuseum – Sikorsky S-55C |publisher=Flymuseum.dk |access-date=23 October 2012}}</ref>

;Germany * 53-4458 – H-19B on static display at the [[Deutsches Museum]] in [[Munich, Bavaria]].<ref>{{cite web|url=http://www.deutsches-museum.de/en/collections/transport/aeronautics/helicopters/sikorsky-s-55/|title=Deutsches Museum: Sikorsky S-55|author=Deutsches Museum|work=deutsches-museum.de|access-date=7 September 2015|archive-date=17 September 2015|archive-url=https://web.archive.org/web/20150917061046/http://www.deutsches-museum.de/en/collections/transport/aeronautics/helicopters/sikorsky-s-55/|url-status=dead}}</ref><ref>{{cite web|title=Airframe Dossier – Sikorsky S-55 / H-19 / HRS / HO4S / Whirlwind, s/n 53-4458 USAF, c/n 55-0845|url=http://aerialvisuals.ca/AirframeDossier.php?Serial=28154|website=Aerial Visuals|publisher=AerialVisuals.ca|access-date=22 October 2016}}</ref>

;India * IZ1590 – S-55C C/N 55-1077, on static display at the [[Indian Air Force Museum, Palam|Indian Air Force Museum]] in [[Palam|Palam, Delhi]].<ref>{{cite web|title=Airframe Dossier – Sikorsky S-55C, s/n IZ1590 IAF, c/n 55-1077|url=http://aerialvisuals.ca/AirframeDossier.php?Serial=147017|website=Aerial Visuals|publisher=AerialVisuals.ca|access-date=22 October 2016}}</ref>

;Israel * 03 – H-19 on static display at the [[Israeli Air Force Museum]] in [[Hatzerim|Hatzerim, South District]].<ref>{{cite web|title=Airframe Dossier – Sikorsky H-19D-4-SI Chickasaw, s/n 03 IDF, c/n 55-0992|url=http://aerialvisuals.ca/AirframeDossier.php?Serial=136533|website=Aerial Visuals|publisher=AerialVisuals.ca|access-date=22 October 2016}}</ref>

;Japan * JG-0001 – H-19C on static display at the [[Tokorozawa Aviation Museum]] in [[Tokorozawa, Saitama]].<ref>{{cite web|title=Experience Exhibits|url=http://tam-web.jsf.or.jp/contxe/modules/tinyd3/index.php?id=2|website=Tokorozawa Aviation Museum|access-date=22 October 2016|url-status=dead|archive-url=https://web.archive.org/web/20160314120633/http://tam-web.jsf.or.jp/contxe/modules/tinyd3/index.php?id=2|archive-date=14 March 2016}}</ref><ref>{{cite web|title=Airframe Dossier – Sikorsky H-19C Chickasaw, s/n 40001 JASDF, c/n 55.690|url=http://aerialvisuals.ca/AirframeDossier.php?Serial=151835|website=Aerial Visuals|publisher=AerialVisuals.ca|access-date=22 October 2016}}</ref> * 40012 – H-19C in storage at the [[Kawaguchiko Motor Museum]] in [[Narusawa, Yamanashi]].<ref>{{cite web|last1=Thompson|first1=Paul|title=Aviation Museums|url=http://www.j-hangarspace.jp/aviation-museums#kawaguchiko|website=J-Hangar Space|publisher=J-HangarSpace|access-date=22 October 2016}}</ref>

;Norway * 56-4279 – H-19 D-4 on static display at the [[Norwegian Armed Forces Aircraft Collection]] in [[Gardermoen|Gardermoen, Akershus]].<ref>{{cite web|last1=Kjærnes|first1=Erling|title=Sikorsky H-19 D 4 Chickasaw|url=http://forsvaretsmuseer.no/Luftforsvarsmuseet/Flyene/Forsvarets-Flysamling/Sikorsky-H-19-D-4-Chickasaw|website=Forsvaret|access-date=21 October 2016|date=26 September 2011}}</ref>

;Portugal * 9101 – UH-19 at the [[Museu do Ar]] on [[Sintra Air Base]] near [[Lisbon]].

;Serbia * 11714 – S-55 on static display at the [[Museum of Aviation (Belgrade)|Museum of Aviation]] in [[Surčin|Surčin, Belgrade]].<ref>{{cite web|title=Sikorsky / Westland / Soko S-55 Mk-5|url=http://www.muzejvazduhoplovstva.org.rs/eksponati.php?jez=eng&id=24|website=Aeronautical Museum Belgrade|publisher=Aeronautical Museum-Belgrade|access-date=21 October 2016}}</ref>

;Thailand * H3-3/97 – Type 3 on display at the [[Royal Thai Air Force Museum]] in [[Bangkok|Bangkok, Bangkok]].<ref>{{cite web|title=Building 5:Helicopters and last propeller fighter|url=http://www.rtaf.mi.th/MUSEUM/BLDG5-2.HTM|website=Royal Thai Air Force Museum|access-date=29 October 2016|archive-url=https://web.archive.org/web/20131026164825/http://www.rtaf.mi.th/MUSEUM/BLDG5-2.HTM|archive-date=26 October 2013}}</ref><ref>{{cite web|title=Airframe Dossier – SikorskyS-55 / H-19 / HRS / HO4S / Whirlwind, s/n H3-3/97 RTAF, c/n 55-0757|url=http://aerialvisuals.ca/AirframeDossier.php?Serial=5771|website=Aerial Visuals|publisher=AerialVisuals.ca|access-date=29 October 2016}}</ref>

;Turkey * 52-7577 – UH-19B on static display at the [[Istanbul Aviation Museum]] in [[Istanbul|Istanbul, Istanbul]].<ref>{{cite web|title=UH-19B Chickasaw|url=http://www.hho.edu.tr/muze/600/uh-19.htm|website=Hava Kuvvetleri Muzesi|access-date=21 October 2016|language=tr|url-status=dead|archive-url=https://web.archive.org/web/20161021200631/http://www.hho.edu.tr/muze/600/uh-19.htm|archive-date=21 October 2016}}</ref><ref>{{cite web|title=Airframe Dossier – Sikorsky UH-19B Chickasaw, s/n 52-7577 THK, c/n 55-714|url=http://aerialvisuals.ca/AirframeDossier.php?Serial=164797|website=Aerial Visuals|publisher=AerialVisuals.ca|access-date=21 October 2016}}</ref> [[File:Historic Aviation Memorial Museum August 2018 18 (Sikorsky HO4S-1).jpg|thumb|Sikorsky HO4S-1 on display at the [[Historic Aviation Memorial Museum]]]]

;United States * Unknown ID – UH-19F on static display at [[Kirtland Air Force Base]] in [[Albuquerque, New Mexico]].<ref>{{cite web|title=Airframe Dossier – Sikorsky UH-19F Chickasaw, s/n 138499|url=http://aerialvisuals.ca/AirframeDossier.php?Serial=42445|website=Aerial Visuals|publisher=AerialVisuals.ca|access-date=31 October 2016}}</ref> * 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.<ref>{{cite web|title=HO4S|url=http://www.navalaviationmuseum.org/attractions/aircraft-exhibits/item/?item=ho4s|website=National Naval Aviation Museum|publisher=Naval Aviation Museum Foundation|access-date=21 October 2016|archive-url=https://web.archive.org/web/20140713183325/http://www.navalaviationmuseum.org/attractions/aircraft-exhibits/item/?item=ho4s|archive-date=13 July 2014}}</ref><ref>{{cite web|title=Airframe Dossier – Sikorsky CH-19E Chickasaw, s/n 130151 USN, c/n 55-0208|url=http://aerialvisuals.ca/AirframeDossier.php?Serial=64066|website=Aerial Visuals|publisher=AerialVisuals.ca|access-date=21 October 2016}}</ref> * 130252 – HRS-3 on static display at the [[Flying Leatherneck Aviation Museum]] in [[San Diego, California]]. It is painted with the unit markings of [[VMM-161|HMR-161]].<ref>{{cite web|title=Aircraft Listing|url=https://www.flyingleathernecks.org/wp-content/uploads/2013/10/Aircraft_Listing.pdf|website=Flying Leathernecks|publisher=Flying Leatherneck Historical Foundation|access-date=21 October 2016|archive-date=4 March 2016|archive-url=https://web.archive.org/web/20160304030559/http://flyingleathernecks.org/wp-content/uploads/2013/10/Aircraft_Listing.pdf|url-status=dead}}</ref> * [[File:StevenUdvarHazy-YH19Static.jpg|thumb|Sikorsky YH-19A as shown at the [[Steven F. Udvar-Hazy Center]]]]49-2012 – YH-19 on static display at the [[Udvar-Hazy Center]] of the [[National Air and Space Museum]] in [[Chantilly, Virginia]]. This airframe was the first S-55 built.<ref>{{cite web|title=Sikorsky YH-19|url=http://airandspace.si.edu/collection-objects/sikorsky-yh-19|website=Smithsonian National Air and Space Museum|access-date=21 October 2016|archive-date=22 October 2016|archive-url=https://web.archive.org/web/20161022040420/https://airandspace.si.edu/collection-objects/sikorsky-yh-19|url-status=dead}}</ref><ref>{{cite web|title=Airframe Dossier – Sikorsky YH-19A Chickasaw, s/n 49-2012 USAF, c/n 55-0001, c/r N2797|url=http://aerialvisuals.ca/AirframeDossier.php?Serial=23009|website=Aerial Visuals|publisher=AerialVisuals.ca|access-date=21 October 2016}}</ref> * 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]].<ref>{{cite web|title=CHICKASAW|url=http://www.pimaair.org/aircraft-by-name/item/sikorsky-uh-19b-chickasaw|website=Pima Air & Space Museum|publisher=Pimaair.org|access-date=21 October 2016|archive-date=21 October 2016|archive-url=https://web.archive.org/web/20161021194138/http://www.pimaair.org/aircraft-by-name/item/sikorsky-uh-19b-chickasaw|url-status=dead}}</ref> * 52-7573 - H-19B on static display at the [[Connecticut Air & Space Center]] in [[Stratford, Connecticut]].<ref>{{cite web|title=Chickasaw|url=https://www.ctairandspace.org/s-55|url-status=dead|access-date=30 July 2023|archive-date=30 July 2023|archive-url=https://web.archive.org/web/20230730043107/https://www.ctairandspace.org/s-55}}</ref> * 52-7587 – UH-19 on static display at the [[National Museum of the United States Air Force]] in [[Dayton, Ohio]]. It is painted as ''Hopalong'', one of the helicopters to make the first transatlantic flight.<ref>{{cite web|title=Sikorsky UH-19B Chickasaw|url=https://www.nationalmuseum.af.mil/Visit/Museum-Exhibits/Fact-Sheets/Display/Article/196103/sikorsky-uh-19b-chickasaw/|website=National Museum of the US Air Force|access-date=21 October 2016|date=5 May 2015}}</ref> * 52-7602 – H-19D on static display at the [[Evergreen Aviation & Space Museum]] in [[McMinnville, Oregon]]. It is painted in U.S. Army scheme.<ref>{{cite web|title=Helicopters|url=http://www.evergreenmuseum.org/helicopters|website=Evergreen Museum Campus|publisher=Evergreen Museum|access-date=21 October 2016|archive-date=31 May 2017|archive-url=https://web.archive.org/web/20170531024716/http://www.evergreenmuseum.org/helicopters|url-status=dead}}</ref><ref>{{cite web|title=Airframe Dossier – SikorskyS-55 / H-19 / HRS / HO4S / Whirlwind, s/n 52-7602 USAF, c/r N55233|url=http://aerialvisuals.ca/AirframeDossier.php?Serial=27423|website=Aerial Visuals|publisher=AerialVisuals.ca|access-date=21 October 2016}}</ref><ref>{{cite web|title=c/n 55-520|url=http://www.helis.com/database/cn/24652|website=helis.com|access-date=21 October 2016}}</ref> * 53-4426 – H-19B on static display at the [[Strategic Air Command & Aerospace Museum]] in [[Ashland, Nebraska]].<ref>{{cite web|title=H-19B "Whirlwind"|url=http://sacmuseum.org/what-to-see/aircraft/h-19b-whirlwind|website=Strategic Air Command & Aerospace Museum|access-date=21 October 2016}}</ref> * 55-0433 – H-19D in storage at [[Fantasy of Flight]] in [[Polk City, Florida]].<ref>{{cite web|title=Airframe Dossier – Sikorsky H-19D Chickasaw, c/n 55-0433, c/r N111VA|url=http://aerialvisuals.ca/AirframeDossier.php?Serial=20216|website=Aerial Visuals|publisher=AerialVisuals.ca|access-date=21 October 2016}}</ref><ref>{{cite web|title=FAA REGISTRY [N111VA]|url=http://registry.faa.gov/aircraftinquiry/NNum_Results.aspx?NNumbertxt=N111VA|website=Federal Aviation Administration|publisher=U.S. Department of Transportation|access-date=21 October 2016|archive-date=21 October 2016|archive-url=https://web.archive.org/web/20161021131943/http://registry.faa.gov/aircraftinquiry/NNum_Results.aspx?NNumbertxt=N111VA|url-status=dead}}</ref> * 55-3221 – H-19D Chickasaw on static display at the [[United States Army Aviation Museum]] at [[Fort Novosel|Fort Novosel, Alabama.]]<ref>{{cite web |title=Our Collection |url=http://www.armyaviationmuseum.org/our-collection |website=United States Army Aviation Museum |access-date=17 July 2023}}</ref> * 55-4943 – UH-19D on static display at the [[Estrella Warbird Museum]] in [[Paso Robles, California]]. This airframe had previously been on display at the [[Museum of Flight]] in [[Seattle, Washington]].<ref>{{cite web|title=Sikorsky UH-19D Chickasaw|url=http://www.ewarbirds.org/aircraft/uh19.html|website=Estrella WarBirds Museum|access-date=21 October 2016}}</ref> * 57-5937 – UH-19D on static display at the [[Valiant Air Command Warbird Museum]] in [[Titusville, Florida]]. It is painted in a USAF rescue scheme. It was previously on display at the [[EAA AirVenture Museum]] in [[Oshkosh, Wisconsin]].<ref>{{cite web|title=Static Non-Flying Collection|url=http://www.valiantaircommand.com/static-collection|website=Valiant Air Command Warbird Museum|publisher=Valiant Air Command|access-date=21 October 2016|archive-date=21 October 2016|archive-url=https://web.archive.org/web/20161021142642/http://www.valiantaircommand.com/static-collection|url-status=dead}}</ref><ref>{{cite web|title=Airframe Dossier – Sikorsky UH-19D Chickasaw, s/n 57-5937 USAF, c/n 55-1221, c/r N37788|url=http://aerialvisuals.ca/AirframeDossier.php?Serial=245|website=Aerial Visuals|publisher=AerialVisuals.ca|access-date=21 October 2016}}</ref> This aircraft is a former Winnebago Heli-Home.<ref name=Winnebago/> * 59-4973 – UH-19D on static display at the [[Camp San Luis Obispo Museum]] and Historical Site in [[San Luis Obispo, California]].<ref>{{cite web|title=H-19 "Chickasaw"|url=http://californiamilitaryhistory.org/H19.html|archive-url=https://web.archive.org/web/20161029175149/http://californiamilitaryhistory.org/H19.html|url-status=usurped|archive-date=29 October 2016|website=The California Military Museum|access-date=29 October 2016}}</ref><ref>{{cite web|title=Airframe Dossier – SikorskyS-55 / H-19 / HRS / HO4S / Whirlwind, s/n 59-4973 USAF, c/n 55-1277|url=http://aerialvisuals.ca/AirframeDossier.php?Serial=9035|website=Aerial Visuals|publisher=AerialVisuals.ca|access-date=29 October 2016}}</ref>

==Specifications (UH-19C)== [[File:Sikorsky H-19A Chickasaw 3-view line drawing.png|frameless|right|3-view line drawing of the Sikorsky HO4S-2]] [[File:Sikorsky H-19A Chickasaw (amphibious) 3-view line drawing.png|thumb|A 3-view line drawing of a Sikorsky H-19A Chickasaw on floats]] {{Aircraft specs |ref=U.S. Army Aircraft Since 1947<ref name="Harding p231">Harding 1990, p. 231.</ref> |prime units?=imp  |genhide=

|eng1 number=1 |eng1 name=[[Pratt & Whitney R-1340]]-57 |eng1 type=9-cylinder air-cooled radial piston engine |eng1 hp=600 |eng1 note= |rot number=1 |rot dia ft=53 |rot dia in= |rot area sqft=2206 |rot area note=<br/> *'''Tail rotor diameter:''' {{cvt|8|ft|8|in}}  |max speed mph=101 |max speed note= |cruise speed mph=85 |cruise speed note= |never exceed speed mph= |range miles=450 |range note= |combat range miles= |ferry range miles= |endurance= |ceiling ft=10500 |ceiling note= |g limits= |roll rate= |glide ratio= |climb rate ms= |climb rate ftmin= |climb rate note= |time to altitude= |disk loading kg/m2= |disk loading lb/sqft= |disk loading note= |fuel consumption kg/km= |fuel consumption lb/mi= |power/mass=

|more performance=  |armament= }}

==Notable appearances in media==  <!-- Please READ [[Wikipedia:WikiProject Aircraft/page content#Popular_culture]] and [[Wikipedia:WikiProject Military history/Style guide#Popular_culture]] before adding any "Popular culture" items.

Please do not add the many minor appearances of the aircraft. This section is only for major cultural appearances where the aircraft plays a MAJOR part in the story line, or has an "especially notable" role in what is listed. A verifiable source proving the appearance's notability may be required. Random cruft, including ALL Ace Combat, Battlefield, and Metal Gear Solid appearances, and ALL anime/fiction lookalike speculation, WILL BE removed.

If your item has been removed, please discuss it on the talk page FIRST. A verifiable source proving the appearance's notability may be required. If a consensus is reached to include your item, a regular editor of this page will add it back. Thank you for your cooperation.-->  {{Main|Aircraft in fiction#Sikorsky H-19 / Westland Whirlwind}}

==See also== {{aircontent |related= * [[Sikorsky H-34]] – developed from H-19 (by lengthened airframe and upgrading engines) * [[Westland Whirlwind (helicopter)]] – British licensed version of S-55 |similar aircraft= * [[Harbin Z-5]] – Chinese variant of Mi-4 * [[Mil Mi-4]] – similar design and built in response to H-19 |lists= * [[List of civil aircraft]] * [[List of military aircraft of the United States]] * [[List of rotorcraft]] }}

==References==

===Notes=== {{Reflist|group=note}}

===Citations=== {{Reflist}}

===Bibliography=== *Duke, R.A., Helicopter Operations in Algeria [Trans. French], Dept. of the Army (1959) *{{cite journal |last1=Elliott|first1=Bryn|title=On the Beat: The First 60 Years of Britain's Air Police |journal=Air Enthusiast |date=January–February 1999 |issue=79 |pages=68–75 |issn=0143-5450}} *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). {{ISBN|1-85310-102-8}}. *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) *{{cite journal |last1=Sonck|first1=Jean-Pierre|title=1964: l'ONU au Congo |journal=Avions: Toute l'Aéronautique et son histoire |date=January 2002 |issue=106 |pages=31–36|trans-title=The United Nations in the Congo, 1964 |language=fr |issn=1243-8650}} *{{cite journal |last1=Sonck|first1=Jean-Pierre|title=1964: l'ONU au Congo |journal=Avions: Toute l'Aéronautique et son histoire |date=February 2002 |issue=107 |pages=33–38|language=fr |issn=1243-8650}} *Spenser, Jay P., ''Whirlybirds: A History of the U.S. Helicopter Pioneers'', Seattle, Washington: University of Washington Press (1998)

== Further reading == *{{Cite book |last1=Núñez Padin |first1=Jorge Felix |last2=Cicalesi |first2=Juan Carlos |title=Sikorsky S-55/H-19 & S-58/T |year=2011 |editor-first=Jorge Felix |editor-last=Núñez Padin |publisher=Fuerzas Aeronavales |series=Serie en Argentina |volume=6 |language=es |isbn=978-987-1682-13-3 |location=Bahía Blanca, Argentina |url=http://www.fuerzasaeronavales.com/?product=libro-sikorsky-s-55h-19-s-58t-serie-en-argentina-n6 |access-date=2014-08-24 |url-status=dead |archive-url=https://web.archive.org/web/20140827083127/http://www.fuerzasaeronavales.com/?product=libro-sikorsky-s-55h-19-s-58t-serie-en-argentina-n6 |archive-date=27 August 2014 }}

==External links== {{Commons category|Sikorsky S-55}} *[https://web.archive.org/web/20080506193533/http://www.redstone.army.mil/history/aviation/factsheets/uh19.html H-19 US Army Aviation history fact sheet] *[http://hrs-helicopter.com USMC Sikorsky HRS (H-19) Database] *[http://www.helis.com/database/model/19/ HELIS.com Sikorsky S-55 (H-19/HRS/HO4S) Database] *{{Internet Archive film | gov.archives.arc.36696 | Transitional Helicopter Flight Training: Part I – Transition to the H-19 }}

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