GB800046A - Improvements in and relating to aircraft rate of climb indicating instruments - Google Patents

Abstract

800,046. Aircraft instruments. SPECIALTIES, Inc. Jan. 27, 1956 [Jan. 28, 1955], No. 2794/56. Class 4. [Also in Group XIX] A rate of climb indicator for aircraft comprises a barometric capsule 19 housed within a closed container 18, the base 19a of the capsule being fast with the container and having a connection 20 with a static pressure line 21. The interior of container 18 communicates with static pressure air through a capillary opening 22 so that movement of diaphragm 19b of the capsule gives an indication of the rate of climb of the aircraft. Such indication, however, lags behind the instantaneous rate of climb due to the metering effect of capillary 22 and to overcome this disadvantage the signal from the capsule 19 is combined in an adding device 24 with a further signal from an accelerometer 10, the combined output from device 24 being used to operate a rate-of-climb indicator 26. The accelerometer comprises a vertically movable mass 10, balanced by a spring 11 and damped by a dashpot 15. In operation, during a climb, the mass 10 will be caused by the vertical acceleration of the aircraft to move downwardly which results in an immediate output, representative of rate of climb, fed to adding means 24. The signal so derived is transient, but before it decays the aircraft will have moved upwardly into relatively less dense atmosphere so that a further signal will be derived from the capsule 19 to complement the decaying signal from mass 10. When the aircraft levels off a negative acceleration will be present in mass 10 which will reverse its signal to means 24 and cancel the enduring erroneous signal from capsule 19. Embodiments are described wherein the coupling between mass 10 and capsule 19 is pneumatic and provision is made to cancel erroneous signals resulting from the effect of sustained accelerations experienced in turns. Further, a gyroscope may be incorporated in the instrument to furnish signals, which are functions of pitch and bank angles of the aircraft, to control the movements of mass 10. In a further embodiment the capsule 19 and mass 10 are mounted in a common housing mounted in the aircraft for banking movement under the control of a servo motor and follow up unit energized by a gyroscope whereby movement of the housing with reference to the instrument panel of the aircraft provides an indication of bank angle.