On 1 May 1949, Sikorsky's technical department was given a very important task: it was asked to create a new helicopter in just seven months, which would be capable of carrying ten passengers in addition to a crew of two.

The first of the five YH-19 prototypes ordered by the US Air Force for evaluation 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.

In 1951, the US Air Force ordered a batch of H-l9As fitted with the same 550 hp Pratt & Whitney R1340-57 engine as the prototypes. Production continued with the H 19B which had a 700 hp Wright R-1300-3 engine and a larger diameter main rotor; a total of 270 were built for the US Air Force, including the SH-19B version for use as a transport aircraft. From 1952, the Army also ordered the H-19, beginning with 72 H-l9Cs. They were subsequently nicknamed "Chickasaw" and redesignated UH-1 9C and UH-1 9D 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 H045-1 (equivalent to the H-19A) and 61 H045-2 (about 30 of these were built as HO4S-3G for the US Coast Guard). The Marines received 99 HRS-2 and 84 HRS-3, which corresponded to the H045 series and were used as troop transports. The aircraft assigned to the SAR divisions of the MATS and US Army Aviation arrived in Korea when the war was nearly over, whereas the Marines were able to test their HRS-ls for rapid assault operations which anticipated full-scale landing operations.

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 2,866 lbs.

The most distinctive feature of the Sikorsky aircraft was the location of the engine in the nose, to enable the cabin to be placed at the center of gravity, thus allowing for considerable variations in payload without affecting stability. Special attention was also paid to the question of 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. The three-blade main rotor had long-life metal blades (they demonstrated a life of over 20,000 hours in lab tests). 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 1154 gallons.

Each leg of the quadricycle undercarriage had its own shock absorber for maximum stability during take-off and landing and manouvers on the ground. 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.

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. 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.

In ten years, Sikorsky produced 1,067 S-55s in military version for no fewer than 30 operators throughout the world. Another 547 were built under license (notably by Westland in England under the name Whirlwind).

Year: 1952 Engine: 608 hp P&W R-1340-57 Rotor diameter: 53 ft Fuselage length: 42 ft 2 in Overall length:62 ft l in Height : l3 ft 4 in Empty weight: 14.950 lb Gross weight:17,200 lbs Max speed: 100 mph Hover ceiling 6,397 ft Serv ceiling: 10,558 ft Range: 1400 miles Capacity: 10 troops or 12,857 lbs

Guido Van Roy is one of Fiddlersgreen most prolific modelers and he's sent us many, many photos as well as actual new designs.. Shown above, is a beta model of the S-55 and it's important to mention a few minor tweaks that have happened since. The forward landing gear is a little shorter, and the cockpit, above, is a little shorter fore and aft. We've since added a cross-section of the fuselage to show how the sides are quite vertical.

Be sure to visit our 'Fun with Igor Sikorsky" page.