They must have seemed like a good idea at the time and many millions of dollars were spent researching them. However, these ten aircraft, although they made it off the drawing board, didn't get much further. From our perspective some were obvious errors but for a few they look like amazing opportunities lost.
Reconnaissance is important in the field and the US Army wanted, in the 1950s, to have a simple personal helicopter that could be operated by pilots with limited flight experience and with a small amount of instruction. It was seen as a potential motorcycle of the air and, certainly, the early tests showed quite a lot of promise. However, once further studies had been conducted it was discovered that the HZ-1 was too difficult to control in untrained hands.
From the Upcoming ueue, submitted by taliesyn30.