GB874845A - Means for controlling the stability of an aircraft - Google Patents

Abstract

874,845. Controlling aircraft. HISPANO AVIACION S.A. Oct. 15, 1957 [March 7, 1957], No. 32190/57. Class 4. Means for controlling the stability of an aircraft comprises an auxiliary aerofoil provided on an aircraft at a point removed from the centre of gravity of the aircraft and means to vary automatically the angle of attack of the aerofoil, in accordance with variations in the lift force acting on the aerofoil and accelerations acting on the aircraft transverse to its longitudinal axis, to apply lift to, or to simulate the application of weight, at that point to obtain a virtual shift in a desired direction of the centre of gravity of the aircraft. The auxiliary aerofoil is preferably located at the forward end of a fuselage whereby adjustment of the angle of attack of the aerofoil produces an aerodynamic force equivalent to the one which would be obtained with a weight placed in the same position on the fuselage as the auxiliary aerofoil, this being stated to cause a virtual shift in the centre of gravity of the aircraft. The aerofoil 5 is mounted for pitch adjustment about an axis 6 upon a rod 7 mounted in bearings for axial movement, the aerofoil being adjusted for pitch by an actuator 4 controlled by a comparator 3 which receives signals from an accelerometer 1, which detects accelerations transverse to the longitudinal axis of the aircraft, and a unit 2 which detects, by movement of rod 7, the magnitude and direction of the aerodynamic force acting upon the aerofoil 5. In one embodiment rod 7 is balanced in a neutral position by springs and it carries a valve body, the movable piston of which is actuated by a spring-balanced mass responsive to accelerations on the aircraft, the valve controlling the operation of actuator 4. Other embodiments are described comprising linkages for supporting the aerofoil in which the angle of attack of the aerofoil may be adjusted by either making the aerofoil rigid with one element of the linkage or by adjusting the whole linkage by an actuator.