Patent GB-623294-A (GB)
Title: Improvements in and relating to ground aircraft trainers
IPC: G09B9/16
Filed: 1947-04-25
Abstract: 623,294. Ground trainers. LINK AVIATION, Inc. April 25, 1947, No. 11187. Convention date, April 25, 1946. [Class 4] A system for use in ground aircraft trainers for simulating gauges indicat. ing quantities dependent upon more than one variable, comprises one or more dummy gauges each having an indicating element responsive to changes in pressure and each connected to a source of subatmospheric pressure by a line in which are arranged a number of valves which are independently operable so as each to vary the pressure in the line in accordance with assumed variations in a particular variable. Means are also provided to simulate fuselage vibration due to unsteady engine running. In the arrangement illustrated for a trainer of the type described in Specifications 370,128 and 481,375, a series of dummy engine gauges are connected to a common suction source S, in addition to which are provided a dummy throttle lever 12, propeller pitch control lever 220, and levers 320, 442, 496 for simulating the operation of radiator shutters, carburetter shutters and cowl flaps respectively. Manifold pressure gauge (216).- This is arranged to operate in response to movement of the throttle lever 12 and in accordance with assumed variations of altitude. The gauge 216 is connected to a manifold pressure unit 24 incorporating an electric followup motor controlled jointly by a link 22 connected to the lever 12 and a capsule 198 operated by an "altitude tank such as described in Specification 481,375. Variations of pressure in the tank operate a valve 164 through a linkage 144, 158, 160, the valve being connected to the suction source S by a pipe-line 185, and to the capsule 198 by a line 190. The assumed altitude may be controlled by a knob 149 operated by the instructor. Tachometer (236).-The tachometer is connected through a pipe-line 234 to a pair of valves 252, 230 controlled by the throttle lever 12 and propeller pitch control lever 220 respectively, the valves being connected to the suction source by lines 232, 275. Outside air temperature gauges (300, 300a).- The air temperature being dependent upon altitude, the gauges are connected by a line 298 to a valve 292 controlled by the altitude tank through links 144, 146, and communicating with the source S by the line 185. Oil temperature gauge (286).-In this case the gauge is controlled jointly by a valve 274 coupled to the manifold pressure unit by links 268, 270, a valve 312 connected to the outside air temperature valve 292 by links 306, 308, 310, and a further valve 358 operated by the radiator shutter lever 320. The latter operates an electric follow-up motor 340 giving a gradual operation of the valve 358 and thus a gradual variation in the reading of the gauge 286. Fuel pressure gauges (384, 384a).-The gauges are controlled by a valve 376 provided with an instructor's control knob 372. Oil pressure gauges (404, 404a).-These are controlled by a valve 394 with a control knob 390. Carburetter air temperature gauge (426).-This gauge is controlled jointly by a valve 410 coniiected to the manifold pressure unit 24 by links 268, 412, a second valve 432 coupled to the outside air temperature valve 292 by the links 306, 308 and a third valve 452 controlled by the carburetter shutter lever 442. Cylinder head temperature gauge (480).- Control is effected jointly by three valves 468, 486, 514 respectively connected to the manifold pressure unit 24, outside air temperature valve 292 and cowl flap lever 496, the latter operating through an electric follow-up motor 504. Engine vibration system.-To simulate the effect of engine speed the throttle lever 12 is connected by links 242, 243, 539 to a unit 538 controlling the speed of a motor 540 carrying an eccentric weight 564 by which vibration is communicated to the fuselage. The movements of the lever 12 do not affect the speed of the motor 540 until a block 244 on the link 242 engages with a block 246 on the link 539. Provision is also made to simulate the erratic firing of the engine due to the carburetter air temperature or cylinder head temperature being too high or too low, the gauges 426, 480 being connected to bellows 568, 578 whose movements control switches in the circuit of the motor 540. When abnormal temperatures are simulated, one or other of the switches is opened and the main motor circuit broken, but the motor is intermittently energized by a rotary cam 582 controlling a further switch 558 in a subsidiary motor circuit.