Original sentence: Igor Sikorsky ranks just short of the Wright brothers themselves as an aviation pioneer, and although he is often claimed to be the first person to achieve volume helicopter production and other helicopter milestones, some evidence exists that this honour should go to Anton Flettner of Germany.The VS-300 was not the first successful rotary-wing aircraft to fly, but it was the first of the single-rotor configuration that became the world standard
Edited sentence: Although Igor Sikorsky ranks just short of the Wright brothers themselves as an aviation pioneer, he is best remembered as the first person to achieve volume helicopter production, a milestone his company accomplished in World War II.Although Sikorsky manufactured over 100 helicopters by wars end, Flettner and Focke-Achgellis helicopters were first in the world to enter mass production.Although Sikorsky's achievements are to be lauded, many common claims regarding Sikorsky's priority in helicopter development are incorrect and should more accurately be attributed to German helicopter pioneers Anton Flettner and Heinrich Focke who achieved many helicopter milestones and records before Sikorsky's first prototypes left the ground.However years earlier, Flettner flew the first single rotor helicopter with anti torque vertical rotor, the Fl 185.The VS-300 was not the first successful rotary-wing aircraft to fly, but it was the first of the single-rotor  with anti torque rotor mounted on the tail configuration that became a post war standard