Back in the 1500’s there was a renaissance man named Leonardo Di Vinci, this man was the first man to develop and draw the idea of a machine that is capable of vertical flight, which we now know as a helicopter. His design would have worked, but only theoretically. Many others tried but were missing two things, the understanding the nature of lift, and an engine.
At the end of the nineteenth century, the internal combustion engine made it possible for the development of full sized models with a power source. But had many problems with the torque: the effect produced by the rotor to force the fuselage to rotate in the opposite direction than the engine. Starting the 20th century, they were taking one step forward and two steps back in their advancement’s. They had problems with dissymmetry of lift: the action that tended to cause the early designed copters to flip over. This had baffled them. Then the swashplate was invented with cyclic pitch control, which allowed the rotor blade angles to be altered so that the lift would be equal on each side of the central shaft. But there were still problems with any one individual helicopter.
November 13, 1907 a French man named Paul Cornu, lifted a twin rotor helicopter into the air without any assistance for a few seconds. No greater advancements were made in till a German prof. Heinrich Focke and engineer Gerd Achgelis started a design in 1932, and then introduced the Focke-Wulf Fw 61 with its maiden flight in 1936. Which had won the world record. Duration: 1hr 21min
Ceiling: 3427m or 11423ft
Average Speed: 123km/h or 76.4mph
Igor Sikorsky had made his first helicopter by 1940, after refining his design he started production by 1941 of the R4. Then by 1943 he had developed the R5, which was still only 2 seater but more capable than the R4. They were produced in substantial numbers and were very limited with the payload. Several hundred of the R5 had seen military service during WW2.