Now an industry leader with unmatched name recognition, Bell Helicopter was the first to obtain certification for a commercial helicopter. Over its rich history, Bell Helicopter has delivered more than 35,000 aircraft to our customers around the world.
http://www.bellhelicopter.com/company/history
History of Helicopters. The first successful rotorcraft was a gyroplane, designed by Sr. Juan de La Cierva in Spain and flown on 17th of January, 1923. His success created much interest world wide and led to the development of the first successful helicopter, the Focke-Wulf, Fw 61 which was first flown in June of 1936 in Germany. In 1933, the Focke-Wulf Co. built Cierva C.19 and C.30 gyroplanes under license. Click here to see Fl 282 in flight.
http://www.scientistsandfriends.com/helicopters.html
Igor I. Sikorsky (1889-1972) invented America’s first practical helicopter – the VS-300. It was also the first successful helicopter in the world to pioneer the now familiar single main rotor with torque-compensating tail rotor design.
http://www.autospeed.com/cms/article.html?&title=The-First-Helicopter&A=111533
In 1938, Igor Sikorsky’s proposal to develop a helicopter to test his theories was accepted by United Aircraft, parent corporation of Sikorsky Aircraft since 1929. The VS-300 was designed in the spring of 1939 and built that summer.
http://www.autospeed.com/cms/article.html?&title=The-First-Helicopter&A=111533
The History of Bell Helicopter. Founded in July, 1935 by Larry Bell as Bell Aircraft Corporation, today's Bell Helicopter continues to set the pace for the industry and expand the scope of vertical lift - but in those early days...
http://www.bellhelicopter.com/company/history
She was the most remarkable pilot in the world: first woman airline captain, first woman to fly a helicopter, first woman to fly a rocket aircraft, first woman to fly a jet and one of the best glider pilots who still set glider record flights at the age of 75.
http://www.scientistsandfriends.com/helicopters.html
The principal designer of the VS-300 was Igor lvanovich Sikorsky, born May 25, 1889, in the Russian city of Kiev. At the age of twelve, he made a rubber band powered flying model of a helicopter.
http://www.autospeed.com/cms/article.html?&title=The-First-Helicopter&A=111533
After the attachment of rubber pontoons, the VS-300 made the world’s first helicopter water landings on April 17, 1941. On May 6, Igor Sikorsky piloted the VS-300 to establish the International Helicopter Endurance record of 1 hour, 32 minutes and 26 seconds.
http://www.autospeed.com/cms/article.html?&title=The-First-Helicopter&A=111533
...In just six months, the team designed and constructed the first Bell helicopter, designing and fabricating parts as they went and solving problems with the use of mathematics, model experiments, intuition and trial-and-error. The first helicopter was officially designated the Model 30... The fuselage was made partly of plywood beams. The original tail cone, which was made at the Buffalo factory, was of riveted magnesium. The rotor blades were a composite of fir and balsa wood, with a steel reinforcement bar down the leading edge.
http://www.bellhelicopter.com/company/history
Construction of the Vought-Sikorsky-300 VS-300 began in late March of 1939. This first configuration had a three-bladed main rotor, 28 feet in diameter, and was powered by a four cylinder, air-cooled, 75 hp Lycoming engine.
http://www.autospeed.com/cms/article.html?&title=The-First-Helicopter&A=111533
when was the first helicopter invented
The first helicopter was invented in 1939. The first helicopter was invented in 1939.  