[4][5] The Hiller HOE-1 became the first production ramjet helicopter, and the Army and Navy flew a small number of these aircraft for a short time to test and evaluate the technology.

[6] The Hiller HJ-1 Hornet was an early attempt to build a jet-powered helicopter using ramjets, with work beginning in 1948.

In the event of power loss, autorotation was found to be difficult due to the drag from the ramjet nacelles.

The tests were successful in proving the viability of the helicopter as a weapons platform, but due to marginal performance, no further conversions or orders were placed.

[1] Also, versions were sent to the U.S. Army's DRC to be evaluated in one of their contests involving the research and development of a light weight, air droppable helicopter for air rescue and reconnaissance, and for a portable, easily put together, and fuel efficient 1 man observation and transport copter.