PV-1 1940 – Frank Piasecki and his P-V Forum’s first design was to be a single-rotor helicopter with a fan-forced, anti-torque system blowing air through the tail cone, and turned by control vanes in the exit, predating the NOTAR* by several decades. PV-1 was not developed beyond the design stage due to high development risk at the early stage of helicopter design. *Acronym for “No Tail Rotor” technology whereby the tail rotor was replaced as anti-torque control by a swiveling exhaust duct at the end of a hollow tail boom.
All Aero 