3. HZ1 Aerocycle

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This has to be one of the most bizarre entries on this list. Not surprisingly, this thing was as dangerous as it looks. The Army scrapped the idea after numerous problems with maneuverability and rotor blades that had a tendency to smash into each other. It may have been a neat idea to have a one-man hover-copter for soldiers to zip around on, but in addition to the technical problems, who would want to ride something like that with blades spinning below you that could chop you up like a salami if you happened to fall off?