6 stamps, pen and ink sketch, dark blue on khaki matting
The concept of rotating wing as seen in the helicopter is as old as man's attempts to fly. Sketches by da Vinci in 1483 that shows an "aerial-screw" machine. In fact the derivation of the word Helicopter is from the two Greek words heliko and pteron, meaning helical and wing respectively. The concept was thought by many to be the best solution in the quest to fly, and vast numbers of designs were tested unsuccessfully before the Write brothers flew their fixed wing airplane in 1903. Ironically, it was only then that the helicopter was successfully flown and refined resulting in Igor Sikorsky's model R-4B in 1942.
