It's past five o'clock so the Vertol 107 prototype has probably just returned from its amphibious demonstration on a nearby lake. The same aircraft also visited Europe in 1959. On the rear fuselage it reads: 'Prototype of US Marine HRB-1 - Swedish Hkp4'. The HRB-1 designation was changed into CH-46A. Photo by: Joop van Bilsen / Nationaal Archief (Netherlands)