Sikorsky S-55 / Chickasaw / H-19 / HO4S / HRS
Westland WS.55 Whirlwind
Orlando Helicopter Airways Inc OHA-S-55 Bearcat
Sud-Est Elephant Joyeuse
S-55
On 1 May 1949, Sikorsky's technical department was tasked to create a new helicopter in seven months, which would be capable of carrying ten passengers in addition to a crew of two.
The H-19 was of all-metal pod-and-boom construction, had quadricycle wheeled landing gear, and carried its single piston engine in its nose. The engine was linked to the gear drive of the three-bladed main rotor by a long extension shaft, and was easily accessible via two large clamshell doors. The arrangement of powerplant and drivetrain allowed the placement of a large and unobstructed box-like passenger/cargo cabin directly below the main rotor blades, thus ensuring that loads of varying sizes and composition would not adversely affect the craft's centre of gravity. The H-19's two-man cockpit was placed above and slightly forward of the passenger/cargo cabin, with the seats placed one either size of the drive shaft, and offered excellent visibility to the front and sides. The craft's high-set tailboom carried a vertical tailplane and a two-bladed anti-torque rotor, and was faired into the rear of the fuselage by a triangular fin.
Special attention was paid to the maintenance. The main parts were easily dismantled in an average of 12-15 hours and were all designed for ease of access (the engine, for example, could be changed in two hours, even without special equipment, and daily inspections took a maximum of 15-20 minutes). The S-55 had a monocoque metal fuselage with aluminum and magnesium light alloy bulkheads and skin. Except for the chrome-molybdenum steel-tube rotor pylon, structure is of aluminium and magnesium semi-monocoque construction. The three-blade main rotor had long-life metal blades (they demonstrated a life of over 20000 hours in lab tests). The main rotors are nitrogen-filled with a hub mounted integral meter. The fuel was contained in two crash resistant tanks situated beneath the cabin in the lower part of the fuselage and had a total capacity of 700 liters. Each leg of the quadricycle undercarriage had its own shock absorber for maximum stability during take-off and landing and manoeuvres on the ground. Wheel track 3.35m. Floats could also be fitted to the legs for emergency landings on water, or the undercarriage could be replaced by permanent metal amphibious landing gear or permanently inflated rubber bag flotation gear. For use with the normal wheels, 'doughnut' pontoons were available which are stowed deflated on each wheel axle and can be inflated in under 5 seconds, when needed for landing on water.
The pilot's compartment above main cabin seats two side by side with dual controls. Cabin located below main lifting rotor may seat from 7 (commercial) to 10 (military) passengers, the 10 passengers being seated three against front and rear walls and two on each side, all facing inwards. Up to six stretchers may be carried, which can be loaded by optional hydraulic power-operated hoist while aircraft is hovering. Pilot's compartment may be entered from the outside or from the cabin so that co-pilot may act as attendant.
Engines were one Pratt & Whitney R-1340 S3H2 Wasp radial air-cooled engine rated at 410kW at 1,525m and with 447kW available for take-off at 915m, or one Wright R-1300-3 radial air-cooled engine rated at 522kW at 2,222m and with 596kW available for take-off at 1,675m. Engine on angular mounting in nose of fuselage with sloping shaft drive to rotor gear box below head. With the R-1300 engine, a hydromechanical clutch with free wheel system is used in the drive to the main transmission, and the drive-shaft from the free wheel unit to the main transmission has flexible rubber couplings on each end. Large clamshell doors in nose of fuselage allow complete accessibility to engine from ground level. Internal fuel capacity 700 litres.
In 1948 Sikorsky received a contract for five Sikorsky S-55 utility helicopters for US Air Force evaluation under the designation YH-19. 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 410kW Pratt & Whitney R-1340-57.
In 1951 the US Air Force purchased fifty H-19A production machines, fitted with the same 447kW / 550hp Pratt & Whitney R-1340-57 engine as the prototypes.
Near the end of 1951 the Air Force accepted the first of an eventual 270 more powerful and slightly modified H-19B aircraft, and at the same time loaned a single H-19A to the Army for operational evaluation in the utility transport and aeromedical evacuation roles.
The H-19B had a 522kW / 700hp Wright R-1300-3 engine and a larger diameter main rotor. The total included the SH-19B version for use as a transport aircraft. Many of which were fitted with rescue hoists.
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 and UH-19D in 1962. Both variants remained in Army service well into the mid-1960s.
In late 1952 orders were placed for the first of some 301 examples of the more capable H-19D variant, 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.
July 1952 saw the world's first transatlantic helicopter crossing when two USAF H-19s traveled from the USA to Wiesbaden (Germany) with stops in Labrador, Greenland, Iceland, Scotland, and the Netherlands on their way. Total flight time was about 52 hours, but because of stops the trip took 21 days.
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 (equivalent to the H-19A) and 61 HO4S-2 (based on the H-19B, about 30 of these were built as HO4S-3G for the US Coast Guard).
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.
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.
In actual service, the H-19 could be relied upon to bring a mean of two tons into the front line for each hour that the aircraft was at work. Of the 20 aircraft assigned to a company, 12 (or 57 per cent) were normally available at any time.
During operational missions, the average daily flight time was four hours per aircraft, a quarter-hour more than in the service of New York Airways, who operated civil S-55s.
The employment of cargo helicopters in Korea was not, of course, limited to the U.S. Army; the Air Force and, in particular, the Marine Corps, have had such aircraft in that theatre for over two years. An especially notable operation was carried out by Army and Marine Corps' helicopters flying side-by-side, in which over 6,000 neutral Indian troops were "trucked" from a carrier in Inchon harbour to the Parimunjoin area. The H-19s were limited to 1,000 lb per lift.
The helicopter requires approximately three hours of maintenance after one day's work. Refuelling time is approximately five minutes.
HRS-3
The 1,000th Sikorsky-built helicopter of the basic S-55 type was delivered to the US Marine Corps in mid-1956. The H-19 Chickasaw holds the distinction of being the 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 Chickasaw made its combat debut during the last stages of the Korean War, and went on to serve in Southeast Asia during the first years of the Vietnam War.
Various techniques and roles were first tested with the S-55 in Korea which were later to form the basis of new military doctrine, such as landing operations behind enemy lines, troop support, recovery of damaged vehicles and their capacity for counterattack and engagement. Another primary task of the helicopter was casualty evacuation or the rescuing of pilots who had come down behind the enemy lines. In the ambulance role, the S-55 could carry up to six stretchers, five of which could be hoisted on board using a mechanical winch fixed outside the cabin. The spacious cabin was designed to accommodate various seating arrangements or freight; it could take up to ten men or a load of approximately 1300kg.
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.
On commercial versions with the R-1300 engine, the tailcone has been sloped down approximately 3.5 degrees to increase clearance of the main rotor in a rough landing.
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.
For a time BEA ran regular services with the Sikorsky S-55 between London Airport at Hounslow, Middlesex, and Waterloo in the centre of the city.
UH-19
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 license. 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.
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.
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.
The OHA-S-55 Nite-Writer is an unprecedented aerial advertising helicopter fitted with a 12.2m x 2.4m array of computer-controlled lights which can display messages and graphics, visible over a distance of 3.2km. More in demand is the OHA-S-55 Bearcat, for which Orlando has developed a quick-change hopper and spray system for crop and fertiliser spraying or seed spreading. Certified in 1991, the Bearcat is powered by a Pratt & Whitney R-1340 engine, which can run on automotive fuel, is fitted with a 'quiet' exhaust, and sold for US$300,000.
In October 1985 the company signed an agreement with China's Guangzhou Machinery Tool Company to licence-build OHA-S-55 Bearcats. Under a 20-year joint venture Guangzhou Orlando Helicopters would first assemble American-built parts before progressing to manufacturing entire units. For carrying heavy external loads, such as logging or construction work, Orlando has developed the OHA-S-55 Heavy Lift which can deal with underslung weights of up to 1361kg. The company has also moved into a unique military market through modifying its S-55s for the US Army Missile Command. As QS-55 Aggressors they have been extensively modified to resemble Mil Mi-24 'Hind-E's as flying targets. The Aggressors can be flown by a pilot or as drones (with dummy pilots in their cockpits) and have a new five-bladed main rotor, extensively redesigned nose, stub wings, and chaff and flare dispensers. A second, more aggressive military version is the armed OHA-AT 55 Defender, design of which began in 1990. Re-engined with a Garrett TPE331-3 turboshaft or a Wright R-1330-3 radial, the Defender also features a stub wing with pylons capable of carrying up to 500kg of weapons, and a five-bladed rotor. Capable of carrying up to 10 fully-equipped troops, the Defender can also be fitted out to accommodate six stretchers and two attendants.
In January 1971 Aviation Specialties Inc received certification for a turbine-powered conversion of Sikorsky S-55 helicopter powered with 1 x 840 hp AirResearch TSE-331, designated S-55-T. Aviation Specialties became Helitec Corporation in 1976.
Whisper Jet Inc produced a modified version of the S-55. The S-55QT is powered by a 650 shp Garrett Air Research TSE331-1OUA-511SW and fitted with a 5 blade main rotor head. Flown by a single pilot, the S-55QT can carry 9 passengers.
Gallery
Versions:
S-55:
Engine: Pratt & Whitney R-1340 S3H2 Wasp radial, 447kW / 550 hp
S-55A
Engine: Pratt & Whitney R-1340 S3H2 Wasp radial, 447kW / 550 hp
Internal fuel capacity: 700 lt
S-55B
Engine: Wright R-1300-3 Cyclone radial, 596kW / 700 hp
Rotor dia: 16.15m
Internal fuel capacity: 700 lt
Cruise: 85 kts
Vne: 115 kts
Pax cap: 10
Crew: 2
S-55C
Engine: Pratt & Whitney R-1340 S3H2 Wasp radial, 447kW / 550 hp
YH-19
Engine: Pratt & Whitney R-1340 S3H2 Wasp radial, 447kW / 550 hp
H-19A
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
H-19A
Engine: Pratt & Whitney R-1340-57, 600 hp
Rotors: 3-blade main; 2-blade tail
Rotor diameter: 49 ft.
Fuselage length: 41 ft 8.5 in
Loaded weight: 6,835 lb
Max speed: 105 mph
Ceiling: 12,900 ft
Typical range: 440 miles at 90 mph
Seats: 2 crew+13-10 passengers
H-19B / SH-19B
Engine: Wright R-1300-3 Cyclone radial, 596kW / 700 hp
Rotor diameter 16.16m
Length: 12.88 m
Height: 4.06 m
Disc Area: 204.95 sq.m
Empty weight:: 2381 kg
MAUW: 3583
Top Speed: 180 km/h
Cruise Speed: 146 km/h
Range: 579 km
Crew: 2
Payload: 10 troops or six stretchers.
Internal fuel capacity: 700 lt
H-19C / UH-19C
Engine: Pratt & Whitney R-1340 S3H2 Wasp radial, 447kW / 550 hp
Maximum speed: 112 mph (180 km/h)
Empty weight: 5,250 lb (2381 kg)
Maximum weight: 7,900 lb (3583 kg)
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)
Crew: 2
Payload: 10 troops or six stretchers
Internal fuel capacity: 700 lt
H-19D / UH-19D
Engine: Wright R-1300-3 Cyclone radial, 596kW / 700 hp
Maximum speed: 112 mph (180 km/h)
Empty weight: 5,250 lb (2381 kg)
Maximum weight: 7,900 lb (3583 kg)
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)
Crew: 2
Payload: 10 troops or six stretchers
Internal fuel capacity: 700 lt
HH 19 Chickasaw
Engine: Wright R-1300-3 Cyclone radial, 596kW / 700 hp
Length: 42.257 ft / 12.88 m
Rotor diameter: 52.986 ft / 16.15 m
Max take off weight: 7900.5 lb / 3583.0 kg
Weight empty: 5261.1 lb / 2386.0 kg
Max. speed: 97 kts / 180 km/h
Cruising speed: 79 kts / 146 km/h
Range: 313 nm / 580 km
Crew: 2
Payload: 10 Pax
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-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
Engine: Wright R-1300-3 Cyclone radial, 596kW / 700 hp
Rotor diameter 16.16m
AUW 3,900kg
Vne: 115 kt
Crew: 2
HRS-1
Engine: Pratt & Whitney R-1340 S3H2 Wasp radial, 447kW / 550 hp
AUW 3,263kg
Crew: 2
Payload: 8 troops
Internal fuel capacity: 700 lt
HRS-2
Engine: Pratt & Whitney R-1340 S3H2-57 Wasp, 550 hp
Rotor dia.: 53 ft
Weight: 6,835 lb
AUW 3,263kg
Max. Speed: 105 m.p.h.
Crew: 2
Payload: 10 troops
Internal fuel capacity: 700 lt
HRS-3
Engine: Wright R-1300-3 Cyclone radial, 596kW / 700 hp
Rotor diameter 16.16m
AUW 3,900kg
Crew: 2
Payload: 10 troops or six stretchers.
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
Engine: Bristol Siddeley Gnôme, 1036 shp
Westland WS-55 Whirlwind HAR.3
Engine: Wright R-1300-3 Cyclone radial, 596kW / 700 hp
Rotor diameter 58 ft
Fuselage length 41 ft 8.5 in
Mauw 7500 lb
Cruise speed 90 mph
Westland WS-55 Whirlwind Mk 4
Engine: Pratt & Whitney R-1340 S3H2 Wasp radial, 447kW / 550 hp
Westland WS-55 Whirlwind HAR4
Engine: Bristol Siddeley Gnôme, 1036 shp
Westland Whirlwind H.A.R. Mk. 5
F.A.A.
Engine: Alvis Lconides Major
Westland WS-55 Whirlwind HAS.7
Rotor diameter 58 ft
Fuselage length 41 ft 8.5 in
Mauw 7500 lb
Cruise speed 90 mph
Westland WS-55 Whirlwind HAR.9
Rotor diameter 58 ft
Fuselage length 41 ft 8.5 in
Mauw 7500 lb
Cruise speed 90 mph
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
Engine: Bristol Siddeley Gnôme, 1036 shp
Westland WS-55 Whirlwind HAR10
Engine: Bristol Siddeley Gnôme, 1036 shp
Westland WS-55 Whirlwind HCC.12
Rotor diameter 58 ft
Fuselage length 41 ft 8.5 in
Mauw 7500 lb
Cruise speed 90 mph
Orlando Helicopter Airways OHA-S-55 Hen-Camper
Engine: 596kW Wright-Cyclone R-1300-3D
Passengers: 4
Orlando Helicopter Airways OHA-S-55 Nite-Writer
Orlando Helicopter Airways OHA-S-55 Bearcat
Engine: Pratt & Whitney R-1340 S3H2 Wasp radial, 447kW
Orlando Helicopter Airways OHA-S-55 Heavy Lift
Slung load: 1361kg
Orlando Helicopter Airways QS-55 Aggressors
Flying target
Main rotor: five-blade
Orlando Helicopter Airways OHA-AT 55 Defender
Engine: Garrett TPE331-3 turboshaft or Wright R-1330-3 radial
Main rotor: five-blade
Warload: 500kg
Passangers: 10 fully-equipped troops or six stretchers and two attendants.
Aviation Specialties S-55-T
Engine: 1 x 840 hp AirResearch TSE-331
Helitec Corporation S-55-T
Engine: 1 x 840 hp AirResearch TSE-331
Whisper Jet Inc S-55QT
Engine: 650 shp Garrett Air Research TSE331-1OUA-511SW
Main rotor: 5 blade
Gross wt: 7700 lb
Service ceiling: 14,100ft
Max range: 365 miles
Max cruise: 98mph
Capacity: 9 passenger
Sud-Est Elephant Joyeuse
