Patent GB-807233-A (GB)
Title: Method and means for producing visual display in grounded aircraft trainers
IPC: G09B9/30
Filed: 1955-09-21
Abstract: 807,233. Flight training apparatus. LINK AVIATION Inc. Sept. 21, 1955 [Sept. 21, 1954], No. 27027/55. Class 4. Flight training apparatus wherein an image of terrain over which a simulated flight is made comprises optical apparatus for projecting the image, which may be adjusted by means responsive to at least one simulated control member in the fuselage 1. The preferred embodiment relates to training apparatus for helicopters. A dummy fuselage 1 is pivotally mounted in a yoke 2 which may be rotated in a bearing 5 by a jack 10 to create rolling movements. An arm 11 fast with yoke 2 carries a jack 12 which applies pitching movements about bearings 3 to the fuselage 1. An inclined screen 20 is mounted beneath and in front of the fuselage and it is surmounted by a projection apparatus 27 which projects an image 101 on to screen 20. The image as viewed at 15 appears in perspective as would a rectangular image disposed in a horizontal or simulated ground plane as represented at 102, an anamorphic lens 86 being provided to give the necessary lateral distrotion of the image. In place of projector 27 a translucent screen may be illuminated by a back projector 160. As shown in Fig. 2, the projector 27 includes a hollow cylinder 30 having an annular flange 31 supported between rollers 32 which are carried by a spider member 34 whereby the cylinder may be rotated about its axis by a motor 35 through gearing 36, 37. Motor 35 is energized by a heading computor (not shown) responsive to signals from the rudder bar mechanism 18. The cylinder 30 and spider 34 are movable vertically on a frame 39 by a motor 40 operating through rack and pinion gearing 41, 42. The motor 40, with a motor 63 to be described, is energized by an altitude computer (not shown) responsive to signals from the collective pitch control 17. A pair of guide bars 47 welded to the lower end of cylinder 30 provide a mounting for a slidable film carriage 53 carrying a representation of the terrain which is moved through a screw and nut mechanism by a reversible motor 49 to provide lateral movement of the film (not shown). The motor 49 and the motor 10, Fig. 1 are both energized by a roll and lateral position computer (not shown) responsive to signals generated by lateral movement of the control column 16. Longitudinal movement of the film is achieved by a motor 52 which, with motor 12, Fig. 1, is energised by a pitch and fore-and-aft position computer (not shown) responsive to signals generated by fore and aft movement of the control column 16. Current to the various motors is fed through slip rings and brushes 54-61. Mounted beneath the film carriage 53, on pivots 66, is a panel 65 which carries the optical projection lens 85. The panel 65 is spring-urged into contact with a slide 506 which is operated by a rack and pinion device 504, 505 operated through a belt drive by the motor 40 to change the angle of the plane of lens 85 simultaneously with changes in the elevation of film carriage 53. A motor 63, previously referred as operated in conjunction with motor 40, is mounted on panel 65 to vary, through gears 82, 84, the focal length of lens 85 simultaneously with elevation of the film carriage 53. An alternative embodiment is described, Fig. 5 (not shown) in which variable magnification of projected images to simulate changes in altitude may be achieved without the use of a variable focal length projection lens. The screen may be curved and the film may be replaced by a three dimensional transparent model of an aerodrome. The anamorphic lens 86 may be dispensed with provided the film or transparancy forming the image for projection displays the appropriate lateral distrotion. Specifications 740,056 [Group XL(c)] and 753,096 are referred to.