Patent GB-590773-A (GB)
Title: Improvements in navigational apparatus for use on aircraft
IPC: G01C21/20
Filed: 1943-11-09
Abstract: 590,773. Navigational apparatus for aircraft. MAY, W. J. Nov. 9, 1943, Nos. 18580/43 and 495/44. [Class 97 (ii)] [Also in Groups XIX and XXXVIII] In an aircraft, indicating means, remotely controlled by the navigating apparatus, gives a visual signal to the pilot of any divergence from his course or operates an automatic steering control, the navigating apparatus comprising a vector triangle consisting of ground, wind and air members. The device is applied to the coursesteering apparatus described in Specification 145,810, [Class 97 (ii)], in which a vector triangle of air-speed bar 6, wind-speed bar 32 and master track arm 34 representing ground speed is set up, the operative length of the air-speed bar 6 being corrected for altitude. As described in Specification 542,792, [Group XIX], a circular table 40 rotatable on a vertical axis bears a course-marked disc 41 adjustable in uniformity with the compass-graduated disc 18 and showing in the semicircle 45 the destination area on an enlarged scale and the semicircle 46 covering the entire course from the point of - departure near the periphery to the destination near the centre. A supplementary track arm 42 adjustable in unison with the master track arm 34 extends radially across the disc 41 indicating the course which the aircraft is pursuing and if the aircraft is on its predetermined course is aligned with the centre line 44 of the straight-line course indicator 43. If the aircraft leaves the desired course, the contact 50 on the supplementary track arm 42 engages one or other of the contacts 48, 49 and illuminates one or other of the lamps 48a, 49a in the pilot's cabin or if the contacts 48, 49 are replaced by rheostats, the varying resistance in the circuits indicates the degree of divergence on galvanometers. The variable resistances can be adapted to operate the automatic pilot, the movement of the track arm being transmitted through the rotor 53, transmitter 54 and receiver 55 of a selsyn generator to a servomotor device 56 which drives the rudder 59. The contacts 48, 49 may be replaced by light-sensitive cells, the variation in the size of the light slit due to the angular displacement of the track arm 42 controlling the supply of electrical energy to the automatic piloting device. The air-speed bar 6 is adjusted longitudinally for alterations in altitude. Variations of the air-speed indicator 60 are transmitted automatically through the selsyn generator 62 or by a follow-up fluid-pressure device or manually from the control 70 through the selsyn device 67 to the pinion 65 which meshes with teeth 66 on the air-speed bar 6. The supplementary track bar 42 may carry a pointer 71 driven by the motor 72 and flexible drive 73 to inscribe the track of the aircraft on the chart 41. An artificial horizon device 74 controls, by air pressure operated means 75, a pinion 76 adapted to move translatively the body of the rheostat 77, the slide 78 being controlled by the master track bar 34 so that the speed of the motor 72 and pen 71 is varied to allow for climbing and descending of the aircraft. A time and distance calculator as described in Specification 590,771 may be included in the apparatus movement of the slide 78 being transmitted to the ground-speed indicating knobs by the cable 80. The compass disc 47 driven from the master compass of the aircraft with the pointer 48 mechanically connected to the centre support of the chart table 40 and maintained parallel to the supplementary track bar 42 may be used as an alternative navigating device, the pilot manipulating the controls to keep the pointer and the north mark of the disc coincident as described in Specification 590,771. Specification 589,338 also is referred to.