Patent GB-805947-A (GB)
Title: Gyroscopic artificial horizons
Inventor: GLENNY ARTHUR PHILIP
IPC: G01C19/44
Filed: 1956-04-27
Abstract: 805,947. Gyroscopic apparatus. SPERRY GYROSCOPE CO., Ltd. April 10, 1957 [April 27. 1956 (2)], Nos. 13029/56 and 13030/56. Class 97(3) In a gyroscopic artificial horizon of the kind in which the means for moving the lever carrying the horizon bar includes a slot with parallel straight sides formed in the lever between its pivot and the horizon bar, extending longitudinally of the lever, and having its end nearer the horizon bar open, and a member or members rigidly secured to the rotor casing on the side of the rotor casing pivot nearer the lever pivot, which member lies within the slot when the rotor casing is in a neutral position and moves the lever in an approximately linear manner in response to angular motion of the rotor casing with respect to the gimbal ring until the angular position of the rotor casing departs to a predetermined extent from the neutral position whereupon the member comes out of engagement with the slot and the horizon bar becomes ineffective to indicate further angular motion away from the neutral position, the width of the slot and the corresponding dimension of the member or members engaging the sides thereof are notably increased beyond the dimensions determined by obvious design considerations so that the relative motion between the sides of the slot and the member or members engaging them is increased in relation to the angular motion of the rotor casing. As shown in Fig. 1, the artificial horizon includes a rotor casing I and is provided with a ball erector 3, of the kind described e.g. in Specification 633,95<SP>4</SP> The rotor casing is pivoted about a pitch axis 4 in the gimbal ring 5, and the gimbal. ring is pivoted about a roll axis 6 to a case 7 closed at one end by a transparent window 7a. The window 7a carries a reference indication, not shown, preferably representing a rear view of an aeroplane, and a horizon bar 8 which is mechanically connected to the rotor casing moves relative to the reference mark to indicate the angle of roll through a range extending for 80 degrees in each direction, and angle of pitch through a range extending between plus and minus 15 degrees. A disc 9 secured to the gimbal ring provides a background against which the horizon bar 8 can be seen clearly. The horizon bar 8 is formed at the end of the lever 10 pivoted to the gimbal ring about an axis 11. Additional means are provided for indicating in a very sensitive manner a range of climbing and guiding angles up to 80 degrees. For this purpose a graduated drum 15 is pivoted to the gimbal ring 5 about an axis 16 and is connected to the gyroscope casing 1 by alink 17. The lever 10 is formed with parallel surfaces 21, 22 on opposite sides of a very short slot which embrace a cam 20 carried by the rotor casing 1. When the aircraft containing the instrument goes into a dive, the rotor casing appears to turn with respect to the instrument casing 7 about the roll axis 4. As a result, the cam member 20 bears against the surface 21 the cam member 20 moves against the surface 21 raising the horizon bar 8 with respect to the reference mark on the window 7a. As the angle of dive increase, the horizon bar moves upwards until the angle of dive reaches a value of 15 degrees. At this point, the lever 10 is held against stops (not shown) by the cam member 20 which now bears on a circular portion 23 of the lever 10. The angle of dive is now indicated only on the drum 15. When the aircraft climbs. the cam 20 bears on the surface 22 of the lever 10, and becomes disengaged when the angle of climb reaches a value of 15 degrees, and the lever 10 engages further stops (not shown). Specification 555,177 also is referred to.