Patent GB-753365-A (GB)
Title: Flight training apparatus
Inventor: CUTLER ALBERT ERNEST
IPC: G09B9/30
Filed: 1954-02-15
Abstract: 753,365. Local viewing. COMMUNICATIONS PATENTS, Ltd. Feb. 15, 1954, No. 4371/54. Class 40 (3). [Also in Group XXXIII] Flight training apparatus simulating, for a student pilot, a view of an aerodrome during a landing approach comprises a television camera for scanning a model of an aerodrome, the camera being mounted on a gantry over the model whereby the camera is moved in response to signals representative of the assumed or computed approach path of a real aircraft and a receiver which projects a representation of the aerodrome on to a screen viewed by the student (see Group XXXIII). The scanning unit 33, shown in chain-dotted lines, comprises a cathode-ray tube 37 rigidly mounted in the unit to act as a light source. The deflecting coils 38 are mounted on a rotatable cylinder 39 and a variable current of saw-tooth waveform is applied to the coils through a conductor 40, slip-rings 42 and a reversing switch 41 actuated every half revolution of the cylinder 39 by a relay 43 energized by a micro-switch 44 associated with a cam surface 45 on the cylinder. A lens 46 and a mirror unit 47 having two angularly disposed reflecting faces are rigidly mounted within the cylinder 39 which has windows 48, 49 cut in its base opposite the faces of the mirror unit. The current in the coils 38 causes the light spot on the face of the cathoderay tube to scan the face of the tube in a series of radial scanning lines, and since the rotating cylinder reverses the direction of the current every half-revolution the scanning lines continuously scan one half only of the tube face with a rotary motion about the axis of the tube, the light rays from the spot being formed into a beam by the lens 46 and reflected alternately by the two faces of the mirror unit on to the surface 5 of the model aerodrome. Light reflected from the parts of the model as they are scanned by the light beam is received by a light-sensitive cell 51 and amplified by an amplifier 60. In the projector unit light from a high-intensity source 54 is collected by a lens 55 and is formed into a parallel beam by a further lens 56 from which it passes through a polarizing prism 57, a Kerr cell 58 and an analysing prism 59 from which it emerges modulated in accordance with signals applied to the Kerr cell from the amplifier 60. The modulated light beam passes to a rotatable line-scanning mirror drum 61 having sixteen faces and a second mirror drum 62 for frame scanning having four faces, the drums being driven in synchronism through a gear train 64 and in synchronism with the cylinder 39 by interconnected magslip units 65 and 50. The light beam from the drum 62 is projected on to a screen to be viewed by the student pilot. The current applied to the conductor 40 is varied by signals from a light-sensitive cell 71 which are magnified by an amplifier 74, the cell receiving light from a source 67 through a lens 68, a screen 69, having a narrow slit therein, and a lens 70, the resulting beam of narrow width being interrupted by each of sixteen sawteeth formed on a disc 66 driven from the gear train 64.