GB690985A - Improvements in or relating to aircraft navigational aid apparatus - Google Patents

Abstract

690,985. Radio navigation. SPERRY CORPORATION. March 15, 1949 [March 16, 1948], No. 7062/49. Class 40 (vii). [Also in Group XXXIII] A navigational aid apparatus for aircraft comprises an indicator displaceable from a reference position to provide a first signal when the craft is travelling in a direction divergent from a predetermined direction, such signal constituting a measure of the rate of displacement across the predetermined path, and to provide a second signal when the craft is turning, and constituting a measure of the rate of turn, the indicator being actuated in response to the algebraic sum of the signals according to the sign convention that the second signal is taken as positive if the rate of turn is one that results in a lateral displacement of the craft in a sense that gives rise to a positive first signal, whereby a zero indication may be provided if the direction of travel diverges from the predetermined path, provided the craft is turning towards such path. The arrangement enables an asymptotic approach path to be flown when the aircraft is alighting. As shown, a cross-pointer meter 10 is provided, the vertical pointer 11 being connected to a directional radio beam receiver 32, localizer receiver 33, which may be of the type described in Specification 646,702, magnetic compass 16, which may be as described in Specification 638,971, (Group XXXVIII], and roll-indicating element of gyro 22, while the horizontal pointer 12 is connected to a pitch-indicating gyro element 50, glide path receiver 55 and an altitude control unit 42, which may be of the type described in Specification 663,913, [Group XXXVIII]. For an instrument approach with a localizer beam, receivers 33, 55 are included in the system with the compass 16 and gyro elements 22, 50. As regards heading, the first or lateral displacement rate signal is derived from the compass 16, rate of displacement being proportional to the sine of the angle of divergence, which for small angles is substantially proportional to such angle, the second or rate of turn signal being obtained from the gyro 22 indicating the angle of bank. In the case of the glide path, the signals are derived from the glide path receiver 55 and pitch-indicating gyro 50. The pilot controls the aircraft in such a manner as to maintain both pointers 11, 12 at their zero positions. For a radio-controlled approach using the directional receiver 32, the altitude control 42 is included in the system, receivers 33,. 55 being excluded. When used as an attitude indicator in cross-country flight the instrument is made responsive to the vertical gyro and compass, the altitude control being optional. The altitude control system forms the subject of Specification 691,029, [Group XXXVIII]. Specification 496,521, [Group XXXVIII], also is referred to.