Wikipedia has the first tethered test flight in late '54. It didn't fly untethered until 55, in 56 the US Army took over testing but this vehicle has no Army ma

Wikipedia has the first tethered test flight in late '54. It didn't fly untethered until 55, in 56 the US Army took over testing but this vehicle has no Army markings and is untethered. 1955 seems fairly likely. https://en.wikipedia.org/wiki/De_Lackner_HZ-1_Aerocycle#Testing https://en.wikipedia.org/wiki/De_Lackner_HZ-1_Aerocycle#Test...