Patent GB-896403-A (GB)
Title: Improvements in or relating to ground-based aircraft flight simulators
Inventor: SHELLEY MEVILLE LESLIE
IPC: G09B9/32
Filed: 1958-11-04
Abstract: 896,403. Grounded aircraft trainers. COMMUNICATIONS PATENTS Ltd. Oct. 29, 1959 [Nov. 4, 1958], No. 35368/58. Class 4. An aircraft flight trainer comprises a compartment representing a forward viewing cabin of the aircraft, and means establishing, forward of the compartment, two separate displays pertaining to the same simulated forward view and so disposed that each of two persons who occupy side-by-side viewing positions in the compartment can observe a separate one of the displays. In Fig. 2, the compartment 40 has a window 42, and two screens 46, 56, in front of the compartment, are illuminated with the same scene by closed circuit projection television tubes 44, 54, through mirrors 45, 55, respectively. Screen 46 is viewed by the pilot, whose eye is indicated at 43, and screen 56 by the co-pilot. An opaque shield (not shown) is placed midway between the screens and the mirrors, so that neither pilot nor co-pilot can see the screen intended for the other. By this means, parallax errors in viewing caused by the closeness of a single screen to the personnel, as compared with the distance of the simulated scene are avoided. In place of the two television tubes 44, 54, a single projection type tube may have its optical beam split by a partially silvered mirror or by a composite mirror having two flat surfaces inclined to one another at a small angle, the two resulting beams each illuminating one screen. When a composite mirror is used, it may be transversable, so that the whole of the beam from the tube may illuminate either screen alone. Further television tubes, of the projection or direct viewing type, may present the same scene to the other crew members or an instructor. Further projection screens may be disposed on each side of the compartment to display simulated sideways views. In alteratives, the tubes 44, 54 may be above the compartment 40, and illuminate the screens without mirrors, 45, 55 or the screens 46, 56 may be light transmitting screens illuminated by the projection type television tubes from behind. To increase the field of view of the pilot and co-pilot, the window 42 in front of each may be replaced by a large rectangular convex lens, e.g. a hollow body filled with a suitable liquid. The projected scenes may be in colour. In Fig. 3, the projection tubes, 44, 54, illuminate the screens 46, 56, directly, and the screens are viewed by the pilots and co-pilots eyes 43, 53, by mirrors 47, 57. Where it is desirable to give the pilot a wide field of view, and the co-pilot may have a more restricted field, the pilot may view a directly illuminated screen in front of the compartment, and the co-pilot may view a smaller screen to the side of the compartment by the means shown in Fig. 3. Alternatively, the co-pilot may have a direct vision television tube at closer range. Fig. 1 shows means for deriving the signals fed to the television tube(s). An appropriate photographic transparency 1 is mounted on the bottom of a tank 4 filled with cooling liquid. An optical system comprising a projection lens 6 with an optical axis, 7 a mirror 18, and two mirrors, 19 20, inclined at right angles, projects an image of the transparency on to a screen 17. A circular portion of the transparency is illuminated by a lamp 9 rotatable about a pivot 8 on axis 7. The transparency is movable in two directions set right angles by simulated Northings and Eastings servos 15, 16, the lamp 9 is rotated about pivot 8 in accordance with simulated azimuth by a servo 23, and mirrors 19, 20 are rotated on shaft 24 in accordance with half this angle by the same servo. The resulting image on screen 17 is circular and centred on the screen, and the reflected extension 7<SP>11</SP> of axis 7, which is at the extremity of a diameter of the image, is stationary on the screen, the image representing that part of the scene on the transparency, which is to be simulated as visible to the pilot or co-pilot, in the correct orientation as seen by a television camera 22 having an optical objective 21. A projector 26 projects above-horizon visual elements, such as clouds or obstacles, onto the back of a light transmitting screen 25 at right angles to screen 17. The television camera 22 is movable about the line of intersection of screens 17 and 25 on arms 28, 29 controlled by a simulated height servo 30, and is rotatable relative to the arms about an axis parallel to that line by a simulated pitch servo 32. The camera is also rotable about the optical axis of the objective 21 by a simulated roll servo 31. By this means the projected image appears correct in scale disposition, and orientation. A camera focussing servo 33 is controlled in accordance with computed height and pitch angle through cam means. Specifications 896,404 and 896,405 are referred to.