Aeronautics and astronautics – Aircraft – heavier-than-air – Helicopter or auto-rotating wing sustained – i.e. – gyroplanes
Patent
1975-10-16
1977-01-25
Blix, Trygve M.
Aeronautics and astronautics
Aircraft, heavier-than-air
Helicopter or auto-rotating wing sustained, i.e., gyroplanes
416 31, 416500, 244 76R, B64C 1144
Patent
active
040047571
ABSTRACT:
A rotorcraft is subject to a rocking motion when on the ground, which is called ground resonance, and in the air which gives the fuselage a waddle type of motion about its center of gravity. both are a form of aeromechanical instability. This fuselage motion is coupled with and accompanied by bending oscillations of the blades with respect to the hub of the rotor of the rotorcraft. An oscillation damper is described which damps the oscillations of the aircraft and thereby eliminates or substantially reduces the rocking and waddle motion of the fuselage. The damper includes a seismic device having a mass-spring combination tuned to the frequency of the rocking motion which will typically be one half or approximately one half of the rotor revolutions per minute at cruising speed and is positioned laterally of and spaced from the center of gravity of the fuselage. The movement of the weight in response to fuselage motion operates a control and the control operates a motor which expands and contracts in response thereto. The motor is connected with the swash plate to change the pitch of the blades of the rotor in proper phase relation with the hub oscillation and thereby provide a vector force which damps the oscillations. The control particularly illustrated is a pair of fluid valves and the motor is a fluid motor.
REFERENCES:
patent: 2568401 (1951-09-01), Lynn et al.
patent: 2687856 (1954-08-01), Doman
patent: 2743071 (1956-04-01), Kelley
patent: 2919081 (1959-12-01), Schon
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patent: 3477665 (1969-11-01), Legrand
patent: 3533425 (1970-10-01), Hannan
patent: 3795375 (1974-03-01), Lemnios
patent: 3938762 (1976-02-01), Murphy
Barefoot Galen L.
Blix Trygve M.
Gallagher William
Montstream John M.
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