The first prototype of the S-55, first flown on 10 November 1949. The S-55 was the first successful single-rotor helicopter capable of transporting significant loads. The key was to put the big piston engine in the nose, and the changeable payload and fuel in the centre of gravity. Initially 49-2012 had a half horizontal tailplane with endplate on this side instead of the two canted fins seen here. Print stamped June 1952.

To our surprise the black S-55 in this nice photo is an early YH-19, one of two tested in Korea. Perhaps the helo is seen in its last hours, since Joe Baugher's website reports: 'With 3rd ARS, crash landed in mudflats near Inchon, South Korea May 2, 1952 after engine failed while returning from evacuation mission. All 3 crew survived and were rescued.' The helicopter did not survive. Photo from: National Archives at College Park, Maryland

Of the five YH-19s, two were tested in Korea from 23 March 1951. They were 49-2014 and 49-2016. 49-2014 to N68634 in 1970. Photo from: US Air Force