The DH-4 was made in 1954, followed by the HZ-1 in 1956. The video shows N64N in the video, but the N64N-1 didn't have water applications. Sources: https://ab

The DH-4 was made in 1954, followed by the HZ-1 in 1956. The video shows N64N in the video, but the N64N-1 didn't have water applications. Sources: https://abpic.co.uk/pictures/view/1140732 https://abpic.co.uk/pictures/view/1140732 > It is the only surviving HZ-1. The prototype, designated DH-4 ... https://transportation.army.mil/museum/coldwar/index.html https://transportation.army.mil/museum/coldwar/index.html > The HZ-1 was tested at Fort Eustis in 1956. https://archive.org/stream/ArmedForcesFilms1956/ArmedForcesFilms1956_djvu.txt https://archive.org/stream/ArmedForcesFilms1956/ArmedForcesF... > IESM-543 . Released July 1956 ... The Aerocycle is an experimental one man flying machine. http://www.aviastar.org/helicopters_eng/lockner_helicovector.php http://www.aviastar.org/helicopters_eng/lockner_helicovector... > DH-4 first flew in January 1955. https://asc.army.mil/docs/magazine2/armyalt-oct-dec-15.pdf https://asc.army.mil/docs/magazine2/armyalt-oct-dec-15.pdf > In 1954, he proposed that if the rotors of a helicopter were on the bottom, a pilot could use his own weight to steer the vehicle using kinesthetic control, similar to riding a bicycle. https://en.wikipedia.org/wiki/De_Lackner_HZ-1_Aerocycle https://en.wikipedia.org/wiki/De_Lackner_HZ-1_Aerocycle > First flight 22 November 1954 https://www.youtube.com/watch?v=VyBHM1vZLzc https://www.youtube.com/watch?v=VyBHM1vZLzc > The De Lackner DH-4 "Aerocycle", later renamed the HZ-1 Aerocycle