It would be right to state that, with the successful flight of the XR-4 in the summer of 1942, the helicopter became a reality in the United States.


The Story of the Winged-S (ed. 1948)

Igor Sikorsky Quotes

It would be right to state that, with the successful flight of the XR-4 in the summer of 1942, the helicopter became a reality in the United States.

It would be right to state that, with the successful flight of the XR-4 in the summer of 1942, the helicopter became a reality in the United States.

It would be right to state that, with the successful flight of the XR-4 in the summer of 1942, the helicopter became a reality in the United States.

It would be right to state that, with the successful flight of the XR-4 in the summer of 1942, the helicopter became a reality in the United States.