Another HJ-1 Hornet prototype. In Eyerman's photos, dated 1951, another example that looks like N8170H does not wear a registration. N8120H is identified as a HJ-1 by the FAA. Was there really a HJ-1 predecessor called HH-120? Photo by: JR Eyerman / Life

Stan Hiller in an early HJ-1 helicopter, as proposed for the civilian 'commuter' market. N8170H is said to be the machine preserved at the Hiller Aviation Museum. Two other prototypes hover overhead. Further development led to the military YH-32 and HOE-1. Photo probably taken in 1952.

Marked 'YHJ-1', this is the prototype of the YH-32 Hornet, but not the original HJ-1 Hornet model as seen in photo 677702. Testing of the extremely noisy ramjets terrified the neighbourhoods surrounding the Hiller factory. Photo from: Vertical Flight Society

One of the early civil prototypes of the Hiller HJ-1 Hornet ramjet-powered helicopter, flown by Stanley Hiller, with bow tie, and Prince Bernhard of the Netherlands. By the standards of early helicopter marketing they are not even overdressed. Bernhard was rated by his RAF instructors as an exceptional, but overconfident pilot. Photo from: Nationaal Archief (Netherlands)