Patent GB-833738-A (GB)
Title: Improvements in or relating to aircraft training instruments for simulating attitude gyroscopes
IPC: G09B9/24
Filed: 1957-07-02
Abstract: 833,738. Grounded aircrew trainers. CURTISSWRIGHT CORPORATION. July 2, 1957 [July 9, 1956], No. 20907/57. Class 4. A grounded aircrew trainer has apparatus for simulating an attitude gyro comprising means responsive to simulated roll and bodily supporting an indicator member, means for rotating the member according to simulated pitch, and means manually operable by the trainee for sequentially positioning the supporting means and the member to represent mechanical resetting of the gyro. Fig. 1 is a horizontal section and Fig. 2 a partly broken away side elevation of the instrument which comprises a casing 1 with a fixed end plate 3 providing one bearing 4 for a shaft 5, the other bearing 4a being supported from the casing 1. The shaft 5 supports a yoke 6 with arms 6a, 6b, which support a shaft 8 to which a sphere 7 is fixed. The shaft 5, yoke 6 and sphere 7 are rotated about the longitudinal axis of the instrument by a flight computor servomotor (not shown) in accordance with the simulated angle of roll. A servomotor 9 mounted on the yoke 6 is energized in accordance with the simulated angle of pitch, and drives the sphere 7 and shaft 8 through gearing 10, bevel gears 44, 45 and a friction clutch 46, 48. A horizon bar 11 is pivoted to the yoke at 11c, 11d and is rotated by the sphere 7 through a pin and slot coupling, (Fig. 12 not shown), such that the bar rotates on its pivots in the opposite sense to the sphere, and its displacement is limited to the edges of the instrument face, Fig. 7. A datum representation of an aircraft 55 on the face can be adjusted relatively to fixed data 55a by a knob 56. The instrument thus represents a conventional gyro-controlled attitude indicator. To simulate mechanical resetting or erection of the gyro prior to flight, the trainee pulls a knob 15 connected through an adjustable shaft 16, 16a to a carriage 17 slidable on rods 17b, 17c fixed to the plate 3. A roller 21 on the carriage contacts a cam 22 on shaft 5, and rotates the cam to centre the shaft, rendering the yoke 6 and horizon bar 11 horizontal. To avoid electrically misaligning the roll servomotor, the drive from this to shaft 5 is taken through a friction clutch which slips when roller 21 drives cam 22. When shaft 5 is centred, roller 21 is free to pass through a slot in cam 22, and the carriage continues moving to the left (as shown). The yoke arm 6b contains a slot 35 engaged by a roller 19 on the carriage, locking the yoke horizontal during the remainder of the resetting process. A roller 18 on carriage 17 contacts a recess 18a in a cam plate 26 axially movable on yoke arm 6b. The cam plate moves to the left ; stressing a spring 27, and a cam slot 28 moves a pin 29 extending through the yoke arm 6b to apply a shoe brake to the drive shaft of motor 9. On further movement of cam plate 26, a roller 36 thereon contacts a cam 37 on shaft 8, and centres the cam, and thus also the sphere 7 and horizon bar 11. The clutch 46, 48 slips during this operation owing to the brake on motor 9, preventing electrical misalignment between the motor and its energizing apparatus. Resetting is then complete. The mechanical force required for resetting is simulated principally by a compression spring 24 acting on shaft 16, and to a lesser extent by the forces required by the actual operation.