Patent GB-1224981-A (GB)
Title: Improvements in or relating to aircraft instruments
Inventor: NEWPORT STANLEY BERNARD
IPC: G01D7/00
Filed: 1967-03-03
Abstract: 1,224,981. Aircraft landing computers. SMITHS INDUSTRIES Ltd. 1 March, 1968 [3 March, 1967], No. 10119/67. Addition to 1,102,781. Heading G4G. In a computing apparatus for aircraft overshoot control in landing approach, an incidence sensor 1 comprising, e.g. pressure-sensitive orifices or deflectable vanes, applies an electric signal representing the angle of incidence α to a summation amplifier 2 subtracting it from a limited signal (a + c DV) derived in summation circuit 8 from a potentiometrically controlled signal representing a and a potentiometrically controlled signal representing c.DV, derived from an acceleration sensor 10 producing a signal representing forward acceleration DV. The output of 2 is limited and subtracted in summation amplifier 4 from a signal representing b 6 derived potentiometrically from the output of a gyro 7 representing pitch angle #. The output of 4 representing D(#)d=(α+b#)# (a+c DV) the demanded pitch rate is limited and subtractively combined in summation amplifier 13 with a signal representing pitch rate (D#) of the aircraft derived from gyro 7 or a differentiating network 14 having transfer function to give an output signal representing the difference between actual and demanded pitch rates, which is indicated at pilot's instrument 15; a, b, c, # 1 , # 2  being constants. Various flight procedures for landing approach and overshoot using the apparatus are discussed (Figs. 2, 3, not shown). In a modification (Fig. 4), summing amplifier 28 combines signal representing a from a potentiometer 31 coupled to the wing flaps 30 over a lag network 29, and also a signal from a potentiometer unit 32 energized over shaping network 38 having transfer function from a summation amplifier 35 receiving from pendulum accelerometer 33 a signal representing (DV+g sin #) from which is subtracted a cancelling signal representing g# from potentiometric unit 34 and pitch gyro 27. A signal representing is added from airspeed sensor 37 over potentiometric unit 36, so that the combined signal represents c.DV. The output from 28 is limited and subtractively combined with a signal representing α from 21, limited, and subtractively combined with a signal representing b# from 27 and potentiometric unit 26; the combination representing (a+c DV)#(α+b#), which is applied to a summation amplifier operating indicator 42 over normally open switch 41 ganged with normally closed switch 43 connecting the amplifier additive input to its subtractive input across capacitor 44. Operation of the switch at overshoot discharges the capacitor across resistor 45 and connects the indicator, so that the latter rises exponentially to the difference signal over a time interval. The indicator may be a director-horizon or centre zero instrument, or a display of the kind described in Specification 853,034 or 886,136 and the terms of the difference may be separately displayed. The difference signal may be applied directly to aircraft control equipment The following abridgments are included in this series since the Specifications were, through an error, not allotted to this Group. References to them will be found in the indexes to this volume.