Patent GB-898975-A (GB)
Title: Indicating instruments
Inventor: ARKELL BASIL HENRY
IPC: G01C19/32
Filed: 1957-06-17
Abstract: 898,975. Aircraft instruments. SPERRY GYROSCOPE CO. Ltd. Sept. 8, 1958 [June 17, 1957], No. 18964/57. Class 4. [Also in Group XIX] An aircraft instrument comprises a visible element of arcuate form pivotally mounted for rotation about an axis parallel to the chord of the arc, and mounted for bodily movement in such a manner that the chord is displaced parallel to itself, the two movements of the element being independently controllable. In Fig. 11, the arcuate element 24 which may be a curved wire or a segmental plate, is located in an instrument face 12 and mounted in bearings 22 on rods 20 secured to a shaft 16 rotatable in bearings 14 by a motor 18 in response to signals from a sensing device S1. The element 24 has a crank 26 connected by link 28 to a crank 30 on a shaft 32 coaxial with shaft 16 and rotatable by a motor 34 in response to signals from a sensor S2. The bearings 14 and motors 18, 34 are mounted on a plate 92 secured to a shaft 94 rotatable by a motor 580 in response to signals from a sensor S4. The sensors may be gyroscopes, pitot tubes, capsules detecting rate of change of static pressure, or radio receivers. Preferably sensor S1 detects rate of climb, horizontal speed, or vertical deviation from a radio beam or otherwise defined flight path, and switching means may be provided to connect motor 18 to any one of three sensors each responsive to one of these variables, which then controls vertical bodily movement of the element 24. Sensor S2 is responsive to the angle of pitch, or the pitch attitude of the tip path plane of a rotary wing aircraft rotor, and controls the rotation of element 24 about its chord line c. Sensor S4 is responsive to angle of roll, and controls the inclination of the chord line c to the aircraft OY axis. A vertical bar (not shown) may be provided, being movable parallel to itself across the instrument face by a motor and sensor (not shown) responsive to the aircraft lateral velocity or to lateral deviation from a prescribed flight path. Alternatively, the bearings 14 and motors 18 and 34 may be fixedly mounted in the instrument, and the angle of roll shown by rotation of the normally vertical bar about the aircraft XO axis. One way of doing this is shown in Fig. 2, wherein fixed bearings 36 support a shaft 38 having rigid rods 42 supporting a long bearing 44 for a shaft 46 to which a rod 48 is secured. A crank 50 on shaft 46 is connected by link 52 to a crank 54 on a shaft 56 rotatable within shaft 38 by a motor 58 and sensor S4 responsive to angle of roll, which is thus indicated by rotation of rod 48 about the axis of shaft 56. Shaft 38 is rotatable by a motor 40 and sensor S3 responsive to lateral velocity or lateral deviation from a prescribed flight path, which is indicated by bodily movement of rod 48 across the instrument face. Another form is shown in Fig. 10, where the shaft 56 driven by motor 58 supports a yoke 76 having bearings 74 mounting a shaft 72 having arms 70 connected to the ends of rod 48. A crank 78 on shaft 72 is connected by link 80 to a horn 82 on a collar 84 slidable on shaft 56. Fences 86 on the collar are engaged by a forked arm 90 on the shaft 380 of motor 40. Motor 58 can thus rotate rod 48 about the axis of shaft 56, and motor 40 can move rod 48 parallel to itself across the instrument face. According to the Provisional Specification, one sensor may comprise an arm rotated uniformly in a horizontal plane, e.g. by attachment to a rotor head. A relative airspeed sensor on the end of the arm provides electrical signals fed to an analyzer which deduces the airspeed and the angle of side slip, the latter controlling motor 40.