Patent GB-910161-A (GB)
Title: Aircraft engine start simulation
IPC: G09B9/18
Filed: 1959-04-24
Abstract: 910,161. Grounded aircraft trainers. ACF INDUSTRIES Inc. April 24, 1959 [April 29, 1958], No. 14013/59. Class 4. A grounded aircraft trainer having means representing the operation of a series of turbojet engines, each responsive to a plurality of pre-requisite starting conditions, and a circuit for simulating the starting of an engine, comprises a switch operable by the trainee for positioning according to the simulated aircraft condition, and an electrical relay system connected to the switch to actuate the engine operating means. In Fig. 1, an engine start relay 10 controls electrical analogue inputs to a conventional fuel flow computer 15 and to an engine noise simulator (not shown). The energizing coil of relay 10 is connectable to a source of voltage 12 through an instructor's fail switch 13, and the contacts of a fuel flow relay 14, an engine speed (r.p.m.) switch 16, a blow out relay 18, and an ignition relay 19. For a normal ground start, the trainee places a switch 47 in its NORMAL position, and a switch 22 in its GROUND START position. If the appropriate condition of a high pressure air accumulator 42 is simulated by apparatus described later, an engine cranking relay 41 is energized over switches 47 and 22, and simulator 42. Relay 41 energizes a conventional r.p.m. computer 17, and one contact of switch 47 energizes the conventional fuel flow computer 15. Relay 14 and switch 16 are then closed. Relay 18 is normally closed, and the ignition relay 19 is energized over switches 47 and 22, over a throttle position device 21 if the throttle is in a position suitable for starting, and over an altitude responsive switch 20 which is closed if the simulated aircraft is on the ground. The contacts of ignition relay 19 are then closed, and relay 10 is energized, and holds itself on by its contact 23 if the ignition relay 19 becomes de-energized. The relay is de-energized if the contacts of switch 13 or 16, or relay 14 or 18 are opened. For a flight start, switch 22 is placed in its FLIGHT START position. The ignition relay 19 becomes energized if the throttle position device 21 simulates a suitable throttle position, and since the aircraft is above ground altitude and switch 20 is changed over by the altitude computer, if a selector device 26 responsive to signals from a conventional mach number computer 50 and altitude computer 51. detects that flight conditions are suitable for a flight start. Relay 18 is de-energized to simulate blowout of the engine if a selector device 55 responsive to signals from the mach number and altitude computers detect conditions in which blow-out would occur. In an emergency, the trainee can put switch 47 into a FIRE position, simulating cutting-off of ignition and fuel flow. Fig. 2 shows the high pressure air accumulator 42. A reversible servomotor 29 drives a pressure indicator 31 through shaft 30. When the instructor places a switch 32 in the CHARGE position, a relay 33 is energized and closes its contacts to energize motor 29 over resistor 40, the motor driving indicator 31 to show increasing accumulator pressure until a limit switch 36 opens. Similarly, if switch 32 is in the DISCHARGE position, relay 34 is energized, and motor 29 is energized over resistor 9, the indicat- or 31 being driven to show decreasing accumulator pressure until limit switch 37 opens. During a simulated start, relay 34 is energized over one contact of relay 33 from switch 22, Fig. 1. Indicator 31 is thus driven to show decreasing pressure. A signal voltage is available for the engine cranking relay over switch 38, until this switch is opened by motor 29 when the simulated accumulator pressure drops below the minimum engine starting value.