Patent GB-897753-A (GB)
Title: Improvements in or relating to training devices, such as ground aircraft trainers
Inventor: GREENHALF DOUGLAS WILLIAM GEOR
IPC: F41G9/00
Filed: 1957-06-05
Abstract: 897,753. Trainers for radio navigation. GENERAL PRECISION SYSTEMS Ltd. May 27, 1958 [June 5, 1957], No. 17903/57. Class 40(7).  A radio navigation trainer of the type in which simulated movement of a target can be controlled by an instructor and simulated movement of an aircraft by a trainee in accordance with a radar-like display is provided with means whereby the instructor may either fix the target position relative to the aircraft or control it relative to axes fixed relative to the ground. Thus the instructor can preset the position at which the target is relative to the aircraft when it is first pickedup before directing the trainee in the interception part of his "flight". After the pick-up point is reached the instructor is able to control the target independently of the aircraft. In the embodiment shown a shaft 11 is positioned in accordance with aircraft heading and carries a resolver 10 fed at 13 with an input representing craft velocity. Two outputs representing the craft's velocities X 1  and Y 1  along the ground axes are obtained and fed respectively to integrators 18 and 20. When the instructor is controlling the target independently of the aircraft (switches 38 in position opposite to that shown) the difference between these velocity outputs and similar outputs for the target are obtained at the inputs to the integrators. The target resolved velocities are obtained from resolver 12 fed with a signal representing target horizontal velocity at 15 and positioned by motor 14 in accordance with any rate of turn signal fed over line 75. The difference between the aircraft and target rate of climb signals fed in at 19 and 21 respectively is fed to a further integrator 16. The outputs of integrators 18 and 20, after being added to signals representing target position relative to the craft at the time of pick-up in summing amplifiers 22 and 24, are fed to resolver 26, also on shaft 11. This resolver provides voltages DA and DL representing distance the target is ahead and displacement to port or starboard relative to the craft. The output of integrator 16 is summed at 32 with a signal representing the vertical separation at the time of pick-up and this signal together with D A  and D L  after passing through summing amplifiers 28 and 30 gives the position of the target on a cartesian coordinate system centred on, and turning with the craft. A co-ordinate converter 34, fed also with bank and pitch angle information transforms the co-ordinate signals into signals suitable for supplying to a simulated radar display 36. If the instructor does not wish to control the target independently by the use of inputs 15, 75 and 21 he moves switch 38 to the position shown and presets the position of the target relative to the craft by feeding in inputs at 62, 63 and 64 representing displacements along the X, Y and Z craft axes. The signals on lines 62 and 63 replace the signals DA and D L  and the signal on line 64 is the sole input to amplifier 32 as the inputs to integrators 16, 18 and 20 and summing amplifiers 22 and 24 are earthed. Resolver 40 is carried by shaft 11 and fed with the inputs on lines 62 and 63 until the pick-up point, then it is braked by clutch mechanism 69-78 and provides voltages over lines 70 and 71 representing target position relative to the craft in ground co-ordinates at the time of pick-up. These voltages are fed to summing amplifiers 22 and 24. In order to enable the direction relative to the craft in which the target commences movement to be preset a control 44 is provided. Its position is combined differentially with that of shaft 11 and used to position resolver 12 by means of synchros 46 and 48 and a loop controlling motor 14.