Sikorsky S-55 / Chickasaw / H-19 / HO4S / HRS
![]() S-55
In 1948 Sikorsky received a contract for five Sikorsky S-55 utility helicopters for US Air Force evaluation under the designation YH-19 (49-2012 to 49-2016). The first of these flew on 10 November 1949 and was characterized by a blunt-ended fuselage, which lacked the broad, triangular fillet connecting the fuselage to the tail boom which distinguished all the later series aircraft. Another characteristic of the YH-19 was the horizontal stabilizer applied to the starboard side of the tail, which was replaced in the production aircraft by two anhedral tail surfaces. These was powered by a 550hp Wright R-1340-S1H2.
![]() Sikorsky YH-19 49-2012
In 1951 the US Air Force purchased fifty-five H-19A production machines (51-3846/3895, -17662/17666), fitted with 447kW / 550hp Pratt & Whitney R-1340-57 engine as the prototypes. Some were converted to Air-Sea Rescue SH-19A and HH-19A after 1962.
Near the end of 1951 the Air Force accepted the first of an eventual 270 more powerful and slightly modified H-19B aircraft (51-3896/3968, 52-7479/7600, -10991/10994, 53-4404/4464, -4878/4885, 56-6673/6674), and at the same time loaned a single H-19A to the Army for operational evaluation in the utility transport and aeromedical evacuation roles
.
![]() Sikorsky H-19B 51-3961
The H-19B had a 522kW / 700hp Wright R-1340-3 engine and a larger diameter main rotor. The total included the SH-19B version for use as a transport aircraft. Many were converted to Air-Sea Rescue SH-19B and HH-19B with rescue hoists after 1962. Redesignated as UH-19B in 1962.
In the fall of 1951 the Army ordered the first batch of an eventual seventy-two H-19C aircraft (serials 51-14242 through -14313). The Army's H-19C was essentially identical to the Air Force H-19A and, like that aircraft, was powered by a 600hp R-1340-57 engine and had two small fins fitted to the lower rear of the tailboom in an inverted 'V’.
They were subsequently nicknamed "Chickasaw" and redesignated UH-19C in 1962. Both variants remained in Army service well into the mid-1960s.
In late 1952 orders were placed for the first of some 336 examples of the more capable H-19D variant (52-7601/7625, 54-1408/1437, 55-3176, -3183/3228, -4937/4944, -4462/4504, -5235/5240, 56-1519/1568, -4246/4283, 57-1616/1641, -2553/2558, -5926/5982), sixty-one of which were transferred to friendly nations under various military assistance programmes.
The H-19D was the Army's version of the Air Force -B model and shared that aircraft's more powerful 700hp engine, downward-sloping tailboom, repositioned horizontal tail fins, and smaller-diameter tail rotor. Redesignated UH-19D in 1962. Versions of the S-55 were also acquired by the US Navy, which signed its first contract on 28 April 1950. Between August 1950 and January 1958, the US Navy received 119 helicopters, including ten HO4S-1 (125506 to 125515, equivalent to the H-19A) and 61 HO4S-2, redesignated as UH-19F in 1962 (based on the H-19B, 30 of these were built as HO4S-3G for the US Coast Guard (1252 to 1258, 1281, 1298 to 1310, and 1323 to 1331, redesignated as HH-19G in 1962).
The 1953 HRS was a USN transport helicopter version of the S-55. First production was sixty as HRS-1; 127783 to 127842. Minor equipment changes were in the HRS-2. 101 were built (129017 to 129049, and 130138 to 130205), of which several were converted to HRS-3 standards. They were redesignated as CH-19E in 1962.
The HRS-3 were powered by a Wright R-1300-2 engine. Twenty-seven were upgraded HRS-2, four were transferred from the USAF, and 103 production were built (130206 to 130264, 137836 to 137845, 140958 to 140961, 141029, 141230, 142430 to 142436, 144244 to 144258, 144268 to 144270, 144666 to 144668, 146298 to 146302, and 146439), of which sixteen went to Spain. They were redesignated as CH-19E in 1962.
The HRS-4 was a planned version for Wright R-1820 engines, none was built.
![]() Sikorsky HO4S-3G 1300
Seventy-nine HO4S-3 were built for the USN (133739 to 133753, 133777 to 133779, 138494 to 138529, and 138577 to 138601) and two US Army H-19B transfers (150193 to 150194).
The Marines troop and assault transport versions were designated HRS-1 and HRS-2 (99 built), similar to the HO4S-1, 151 of which were delivered from April 1952. Eighty-four HRS-3 helicopters with Wright R-1300-3 engines were also built. The aircraft assigned to the SAR divisions of the MATS and US Army Aviation arrived in Korea in January 1953 with the 6th Transportation Company, whereas the Marines were able to test their HRS-1s for rapid assault operations which anticipated full-scale landing operations. MATS Air Rescue versions were designated SH-19B and became HH-19B.
Powered by a Pratt and Whitney engine of 600 h.p. or a Wright engine of 800 h.p., the H-19 has a "brochure" capacity of eight troops, six litters, or a maximum of 1,500 lb of cargo, which can be carried over a distance of some 100 miles at a conservative gross weight of 6,835 lb. The maximum useful load is 3,033 lb, which gives a range of 400 miles, or 1,000 miles with extra tankage. The normal cruising speed is 80 to 86 m.p.h., with a fuel consumption of 31 Imp. gal/hr. ![]() HRS-3
![]() Sikorsky S-55
The S-55 received American civil type approval on 25 March 1952 and the model with the Pratt & Whitney R-1340 engines became the S-55A, while the version with the Wright engine was designated S-55B.
The first S-55 in commercial use in the world went into service in British Columbia to build the Alcan project in Kitimat, where the building of power lines by helicopter was another first. In 1952, the helicopter became the first rotary wing craft to be used for commercial links in Europe; it was then flown by the Belgian airline Sabena between the chief towns in Belgium and Lille, Rotterdam, Bonn and Cologne, starting on 1 September.
![]() Sabena S-55
For a time BEA ran regular services with two Sikorsky S-55 between London Airport at Hounslow, Middlesex, and Waterloo in the centre of the city.
![]() BEA S-55
The Whirlwinds were equipped with exterior emergency floatation gear.
![]() UH-19
The RCAF included six H-34 transports for service with No.108 Comuniation flight in duties connected with construction of the Mid-Canada radar line on the 55th parallel.
![]() RCAF No.108 Comuniation flight H-34
Sikorsky manufactured a total of 1,281 S-55's in ten years of continuous production commencing in 1949 and another 547 were built under licenseby Mitsubishi, Sud Aviation, and Westland. It was used by many military services including the RCAF (as the UH-19 and by the RCN (as the HO4S-3) on ‘plane guard’ duties with aircraft carriers.
Licence-production was undertaken by SNCA du Sud Est in France as the Sud-Est Elephant Joyeuse, in Japan by Mitsubishi, and by Westland in the UK, the latter developing versions with the Alvis Leonides Major piston engine and with the Bristol Siddeley Gnome turboshaft under the family name Whirlwind. 2.HIBM in Turkey assembled the H-19 Chickasaw under licence from Sikorsky during 1958. When Westland began producing the S-55, it specified that the American engine would be used until a more suitable British powerplant was available. To meet this requirement, Alvis developed a double radial called the Leonides Major, which delivered 882hp derated to 750hp. The re-engined Whirlwind flew in 1955. It was followed in 1956 by the Mk.7 version intended to replace the old Fairey Gannet antisubmarine aircraft.
The Series 1 and 2, powered respectively by a Pratt & Whitney R-1340 or Wright R-1300 engine or the 755hp Alvis Leonides Major 755.
Installation of Wright R-1300 engines produced the Whirlwind Mk 3 in 1953, followed by the Mk 4 with new P&W R-1340 engines for use in the tropics; then Alvis Leonides Major engine. The RAF also ordered this helicopter for transport and rescue missions: the Whirlwind HAR Mk.2 (the same as the naval version except for some differences in equipment) joined the Transport and Coastal Command Units from 1955. With Wright R.1300 engines, the Whirlwind Mk.3 went into production for the Royal Navy in 1953 and operated for many years from both ship and shore bases. The subsequent RAF HAR Mk.4 version was modified for use in the tropics and fitted with a new variant of the Pratt & Whitney R-1340. It was used in Malaysia.
![]() WS.55 Whirlwind HAR.3
The turbine-powered S-55 made its first flight as the Whirlwind Series 3 in February 1959, powered by a General Electric T58 and introduced a new nose profile which offered better visibility. At the end of the year a Series 3 flew with a 1050shp Bristol Siddeley Gnorne free-turbine - the licence-built version of the T58. The new turboshaft engine was lighter and more powerful than the piston engine it superseded and offered improved performance and reliability.
The Royal Navy ordered a substantial number for anti-submarine duties under the designation Westland Whirlwind HAS.7. Deliveries began in May 1957.
![]() Westland HAS.7
A total of sixty-eight new air-sea rescue HAR10 and transport HC10s were manufactured by Westland and a number of Whirlwind HAR2 and HAR4 piston-engined helicopters were subsequently re-engined.
Like the S-55, the Series 3 has a single door on the left side. The pilot and co-pilot sit above and behind the engine which places their cabin directly under the centreline of the main rotor. The rotor is hydraulically operated for both cyclic and collective pitch controls. Forward vision for landing was not ideal in earlier versions of the Whirlwind since the engine housing was in the nose. The turbine version was better since, though the nose was longer, it was at a more raked angle. Unlike the US turbine-powered S-55, the Whirlwind Series 3 has its engine exhaust on the left side almost immediately above the forward wheel, which can make cargo loading slightly hazardous if the engine is running or the exhaust hot. The turbine engine can be retrofitted to Series 1 and 2 machines.
![]() Whirlwing HR.5
The first RAF unit to employ the HAR10 was No.225 Squadron, Transport Command, which became operational with the aircraft on 4 November 1961.
Used by the RAF in Europe, the Mediterranean and the Far East, the last squadron to be equipped with the aircraft Cyprus based No.84 Squadron converted to the Westland Wessex in March 1982.
Westland built a total of 364 S-55s under licence between 1953 and 1966, including 68 WS-55 civil aircraft. Most turbine-powered WS-55 Series 3s were converted from piston-engined Series 1s and 2s.
In 1964 Orlando Helicopter Airways Inc, of Sanford, Florida, was founded by Fred P. Clark to support, and in some cases, re-start production of Sikorsky helicopters no longer built by the parent company. In addition to a huge spares resource, Orlando Helicopters now holds the FAA type certificates for all H-19 and S-55 models. Several versions of the S-55 have since been developed by the firm. These include the OHA-S-55 Hen-Camper, a fully fitted out VIP version seating four passengers. New equipment includes a shower, wash-basin and toilet, air conditioning, carpeting and sound-proofing. An optional hydraulic winch, cargo sling or exterior spot-light can also be fitted. The Heli-Camper is powered by an overhauled and reconditioned 596kW Wright-Cyclone R-1300-3D engine.
H-19A / SH-19A
Engine: Pratt & Whitney R-1340-57, 600 hp
Rotors: 3-blade main; 2-blade tail
Rotor diameter: 53' 3"
Fuselage length: 41 ft 8.5 in
Loaded weight: 6,835 lb
Max speed: 115 mph
Cruise: 90 mph
Ceiling: 12,900 ft
Typical range: 440 miles at 90 mph
Seats: 2 crew+13-10 passengers
H-19B / SH-19B / UH-19B
1951
Engine: Wright R-1300-3 Cyclone radial, 596kW / 700 hp
Rotor diameter 16.16m / 53'0"
Length: 12.88 m / 42'3"
Height: 4.06 m
Disc Area: 204.95 sq.m
Empty weight: 2381 kg
MAUW: 3583
Useful load: 2650 lb
Top Speed: 180 km/h / 112 mph
Cruise Speed: 146 km/h / 91 mph
Range: 579 km / 360 mi
Crew: 2
Payload: 10 troops or six stretchers.
Internal fuel capacity: 700 lt
H-19C / UH-19C
1952
Engine: 600hp R-1340-57
Useful load: 2705 lb
Max speed: 101 mpg
Cruise: 85 mph
Range: 450 mi
Ceiling: 10,500 ft H-19D / UH-19D
1952
Engine: Wright R-1300-3 Cyclone radial, 596kW / 700 hp
Rotor diameter: 53 ft (16.2 m)
Fuselage length: 42 ft 3 in (12.9 m)
Overall height: 14 ft 8 in (4.5 m)
Empty weight: 5,250 lb (2381 kg)
Maximum weight: 7,900 lb (3583 kg)
Useful load: 2650 lb
Maximum speed: 112 mph (180 km/h)
Cruise: 91 mph
Range: 385 mi
Ceiling: 12,500'
Crew: 2
Payload: 10 troops or six stretchers
Internal fuel capacity: 700 lt
HO4-1
U.S. Navy anti-submarine
Engine: Wright R-1820, 1,025 hp
HO4-2
U.S. Navy anti-submarine
Engine: Wright R-1820, 1,025 hp
HO4S
Engine: P&W R-1340-57
Main rotor: 53'3"
Length: 42'1"
Max speed: 115 mph
HO4S-1
Engine: Pratt & Whitney R-1340 S3H2 Wasp radial, 447kW / 550 hp
AUW 3,263kg
Crew: 2
Internal fuel capacity: 700 lt
HO4S-2
Engine: Pratt & Whitney R-1340 S3H2 Wasp radial, 447kW / 550 hp
AUW 3,263kg
Crew: 2
Payload: 10 troops or six stretchers
Internal fuel capacity: 700 lt
HO4S-2G
Engine: Pratt & Whitney R-1340 S3H2 Wasp radial, 447kW / 550 hp
HO4S-3 / UH-19F
Engine: Wright R-1300-3 Cyclone radial, 596kW / 700 hp
Rotor diameter 16.16m
AUW 3,900kg
Vne: 115 kt
Crew: 2
HO4S-3G / HH-19G
HRS
Engine: P&W R-1340-57
Main rotor: 53'3"
Length: 42'1"
Max speed: 115 mph
HRS-1
HRS-3 / HU-19E
HRS-4
U.S. Marine assault transport
Engine: Wright R-1820, 1,025 hp
Westland Whirlwind H.A.R. Mk. 1
F.A.A.
Engine: Wright R-1340
Westland Whirlwind H.A.R. Mk. 2
R.A.F
Engine: Wright R-1340
Westland WS-55 Whirlwind HAR2
Westland Whirlwind H.A.R. Mk. 5
F.A.A.
Engine: Alvis Lconides Major, 850 hp
Westland WS-55 Whirlwind HAS.7
Engine: 1 x Alvis Leonides Major Mk.155, 750 hp
Rotor diameter: 53 ft
Main rotor disc area: 2206 sq.ft
Main rotor: 3 blade
Fuselage length: 41 ft 8.5 in
Height: 13 ft 3 in
Empty weight: 5580 lb
MAUW: 7800 lb
Fuel capacity: 170 gal
Max speed: 109 mph at SL
Cruise speed: 86 mph
Service ceiling: 13,800 ft
Range: 400 mi
Tail rotor: 2 blade
Westland Whirlwind H.A.R. Mk. 21
Westland Whirlwind H.A.S. Mk. 22
Engine: Wright R-1820, 1,025 hp
Westland WS-55 Whirlwind HC10 Helitec Corporation S-55-T
1971
Engine: 1 x 840 hp AirResearch TSE-331-3U-303
S-55-GW
Engine: 700hp Wright R-1300
Whisper Jet Inc S-55QT
Sud-Est Elephant Joyeuse
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