GB893313A - Roll-yaw presentation device - Google Patents

Abstract

893,313. Aircraft instrument systems. LEAR Inc. Dec.14, 1959 [Dec.24, 1958], No. 42355/59. Class 40 (1). An aircraft instrument system provides first and second signals each indicating deviation about the roll axis, a third signal indicating deviation about the yaw axis and a fourth signal indicating deviation about the pitch axis ; the indicator can be switched to receive either the first signal or a combination of the second and third signals modified in accordance with the fourth signal. In the Figure a vertical gyro 20 is mounted in gimbals 22 and 23, and has its axis stabilized in the vertical by means not shown, while a directional gyro 21 is mounted in gimbals 25, 26 and 27, and has its axis stabilized in the horizontal by means not shown. The outer gimbals of the gyros are suspended from a common gimbal 29, the long axis of which is fore-and-aft so that rolling of the craft is detected by a pick-off 44 to provide the first signal. A second roll signal is obtained from a pick-off 38 on the vertical gyro and passed to one of the coils of the rotor 33 of a resolver. A yaw signal is applied to the other coil of the resolver rotor from a pick-off 41 on the outer gimbal of the directional gyro. The rotor is turned by a motor 34 in accordance with a pitch signal from a pick-off 35 on the outer gimbal of the vertical gyro. The output of the stator 32 is connected to a switch 46 as an alternative input to the roll signal from the pick-off 44. One of these signals is passed to a motor 51 which rotates a sphere 10 about the axis 16, so that roll information is displayed to the pilot in the form of angular displacement of a mark 18 on the frame 12 of the sphere relative to a fixed mark 19. Normally, the switch 46 passes the roll signal from pick-off 44 to the indicator, and at the same time a ganged switch 47 is open. When the aircraft is climbing or descending, this roll information is inaccurate on account of the roll axis not being parallel to the surface of the earth, and the inaccuracy increases as the flight approaches vertical. To enable the wings to be kept level and the pitch axis parallel with the surface of the earth it is then necessary to modify the roll signal, and switch 46 is put into its alternative position, thus closing switch 47. By the action of the resolver 33 the roll signal from pick-off 38 is progressively replaced by the yaw signal from pick-off 41 as the pitch of the craft increases so that the presented information will be correct. At the same time, the roll signal from pick-off 44 is passed to a torquemotor 30 to lock the common gimbal 29 to the frame of the craft.