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This page is dedicated with upmost respect to
The Sikorsky S-55: On May 1, 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 November 7, 1949. It was characterized by a blunt-ended fuselage which lacked the broad, triangular fin connecting it to the tail boom that distinguished all of the later S-55s. Another characteristic of the YH-19 is the horizontal stabilizer on the starboard side of the tail cone which was replaced in the production aircraft with one on both sides. The S-55 is an all metal pod-and-boom construction with quadricycle wheeled landing gear and carries its single piston engine in its nose which is easily accessible via two large clamshell doors. The engine is connected to the main transmission by a 45 degree drive shaft. This innovative arrangement of power plant and drive train allows the placement of a large and unobstructed room-like passenger/cargo cabin directly below the main rotor blades, thus ensuring that loads varying in sizes and composition will not adversely affect the helicopter's center of gravity. The S-55's two-man cockpit is placed above and slightly forward of the passenger/cargo cabin with the seats placed on either side of the drive shaft which offers excellent visibility to the front and sides. The high-set tailboom carries a vertical tailplane and a two-bladed anti-torque rotor and was connected into the rear of the fuselage by a triangular fin. Special attention was also paid to ease of maintenance. The dynamic components are easily dismantled in an average of 12-15 hours and are all designed for easy access (the engine, for example, can be changed in two hours even without special equipment and daily inspections take a maximum of 15-20 minutes). The S-55 has a fuselage made of aluminum and magnesium light alloy bulkheads and skin. The fully articulated rotorhead has three aluminum blades that have demonstrated a life of over 20,000 hours in lab tests. The fuel is contained in two crash resistant tanks situated beneath the cabin in the lower part of the fuselage and have a total capacity of 190 gallons. Each leg of the landing gear has its own shock absorber for maximum stability during take-off, landings and maneuvers on the ground. Floats can also be fitted to the legs for emergency landings on water. 
Various techniques and roles were first tested with the S-55 in the Korean War which were later to form the basis of the new military doctrine, such as landing operations behind enemy lines, troop support, recovery of damaged vehicles and their capacity for counterattack and engagement. The Marines were able to test their HRS-1s for rapid assault operations. The Army's H-19 Chickasaw holds the distinction of being the Army's first true transport helicopter and 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 war (having arrived in Korea in January 1953 in the hands of the 6th Transportation Company), and went on to serve in Southeast Asia during the first years of the Vietnam War and remained in Army service well into the mid-1960s. Another primary task of the helicopter was casualty evacuation and the rescuing of pilots who had come down behind enemy lines. In the ambulance role the S-55 could carry up to six stretchers.
The above oil was painted by Robert Moore in 1953. Sikorsky commissioned him on three pieces that ran in publications like The Saturday Evening Post, Life and Time. This painting is of Marine Squadron HMR-161 and helicopter HR-11. That squadron was highly decorated and was the first in the world to take troops behind enemy lines using helicopters. HMR-161 originated techniques that are still used in the military today.
Saturday Evening Post Ad (1953)
In the 80's Orlando Helicopters also did many conversions on S-55's. They built an S-55 Heli-Camper, a propane-powered conversion, agriculture conversions, restorations and mock-ups of the Mil Hind helicopter for the U.S. government that were made remote control and shot down by different artillery. That is when the 5-bladed rotor system was invented that Whisper Jet uses today.
Some of the World Records established by the Sikorsky S-55:
* First scheduled helicopter service (1953)
http://www.globalsecurity.org/military/systems/aircraft/h-19.htm
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