Patent GB-962031-A (GB)
Title: Improvements in aircraft simulating apparatus
IPC: G09B9/18
Filed: 1962-04-24
Abstract: 962,031. Electric analogue calculating. CURTISS-WRIGHT CORPORATION. April 24, 1962 [April 24, 1961], No. 15654/62. Heading G4G. [Also in Division B7] An analogue computer in aircrew simulating apparatus comprises propeller shaft r.p.m. (N) and propeller blade pitch angle (# p ) servo systems, from which signals representing propeller load torque and propeller windmill torque (the latter due to the relative wind acting on the propeller to tend to drive it, and considered as effective in all propeller operating conditions) are derived, and means for producing a signal representing engine output torque (#), the three torque signals being used as inputs to the N servo system. In the Figure, a simulated turbo-prop engine is controlled by a power lever 10 and condition lever 11, the latter selecting the value of N at which the engine r.p.m. is to be stabilized by automatic control of #p . A fuel flow (FF) servo system 15 is controlled by a single input from potentiometer 19 driven by a temperature datum control (TDC) system 14 and energized by a signal from a potentiometer 13 driven by the power lever 10 and energized by a signal ##, # being the adiabatic temperature ratio. A potentiometer 22 driven by the FF system provides a signal modified in accordance with N by potentiometer 32, and providing one input to the turbine outlet temperature (TOT) system 25. The other input is a compressor intake temperature signal available over resistor 53 from a part of the computer not described. A potentiometer 54 driven by the TOT system provides one input, over resistor 24, to the TDC system, the other input being from potentiometer 12 driven by the power lever. Thus the FF, TOT, and TDC systems form a loop; the stable state of which is primarily determined by the power lever. Potentiometer 36 driven by the TOT system and energized by a signal representing 6 ##, # being the ram air pressure/ambient air pressure ratio, provides a signal representing the engine output torque which energizes a torque indicating servo system 26, and is one input, over resistor 29, to the N servo system 27. The second input, representing propeller load as a function of #, #, N, and #p is obtained by energizing potentiometer 34 driven by the N servo system, by a signal representing # ## the slider 34<SP>1</SP> energizing potentiometer 44 driven by the # p  servo system 45. Slider 44<SP>1</SP> provides the required propeller load signal. The windmill torque input signal to the N servo system is obtained from potentiometer 47 driven by the # p  servo system, and energized by a signal # ##. A non-zero resultant input to the N summing amplifier 28 simulates a resultant torque on the propeller shaft, and is accompanied by a corresponding increase or decrease in N until the consequent variations in the inputs restore the balance. The # p  servo system 45 receives one input from potentiometer 63 driven by the condition lever 11, and another input from potentiometer 33 driven by the N servo system. Any alteration in N unbalances the # p  system to vary the propeller load and windmill torque inputs to the N system until potentiometer 33 is restored to its former position and rebalances the # p  system at a new value of # p . Movement of the condition lever unbalances the system, which in turn unbalances the N system, until potentiometer 33 is driven to a new setting at which the # p  system is rebalanced. Thus the N and # p  systems interact to hold N at a value determined by the setting of the condition lever. Potentiometer 63 is shown as shorted over its range corresponding to reverse pitch setting, a cam 64 operating a switch 6x when the condition lever is moved to a reverse pitch setting to supply a fixed reverse pitch signal from contact b to the # p  system.