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INHERENT STABILITY CONTROL VERSUS CONTROLLING INHERENT STABILITY
In the early 1950’s research was conducted by the NACA, (the National Advisory Committee on Aeronautics), precursor to the National Aeronautics & Space Administration or (NASA), on the feasibility of a one-man flying platform for combat use. Initial tests involved pilots "flying" tethered platforms. An NACA engineer named Charles H. Zimmerman based the concepts investigated in these tests on the theory that if the rotors of a helicopter were placed along the longitudinal axis of the aircraft the aircraft would have inherent stability. Mr. Zimmerman called this concept “kinesthetic control”. (CLICK HERE TO LEARN MORE ABOUT PRECESSIONAL CONTROL: PRIMER ON GYROSCOPICS AND PRECESSION) It was hoped that kinesthetic control would allow a pilot to fly such platforms with little training, which proved very successful.
Historically the Hiller VZ-1 Pawnee Flying Platform seen above was the first ducted fan VTOL aircraft ever to fly carrying a man in un-tethered, free flight out of ground effect. While the Hiller machines demonstrated the merits of Zimmerman’s "kinesthetic control“, it was this "natural" tendency to "right" it’s self, like a gyro, that persuaded Army decision makers to moth ball the aircraft as having "TOO" little control because of "TOO" much stability.
Airborne Autonomous Systems' experiments have shown that when two propellers, with the proper mass relative to the gross weight of the aircraft, are placed along the longitudinal axis of an aircraft, like the HOVTOL, and are counter rotated, precession causes rolling moments to translate to pitching moments by 90 degrees. This inherent gyroscopic precession control thus greatly simplifies flight control of the HOVTOL in hover and VTOL transitions without complex thrust vectoring for rolling moments. An example of this gyroscopic precession roll control phenomenon can be seen in the attributes of a toy called the "TUBE GYRO" which can be seen or purchased for verification experiments at the following link: http://www.gyroscopes.co.uk/
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