Patent GB-748557-A (GB)
Title: Improvements in or relating to apparatus for simulating flight conditions of high speed aircraft
IPC: G09B9/20
Filed: 1953-05-21
Abstract: 748,557. Electric analogue calculating systems. CURTISS-WRIGHT CORPORATION. May 21, 1953 [June 2, 1952], No. 14296/53. Class 37. [Also in Group XXXIII] In apparatus for simulating the aerodynamical conditions of attitude and motion of subsonic flight of a high-speed aircraft, employed in the training of pilots, a range of simulated pupil-operated main and trimming rudder elevator and aileron controls, throttle, and engine speed controls develop representative electric deflection signals which are supplied to a complex computing system for solving known aerodynamical equations of flight, comprising plural interconnected and interacting electro-mechanical servo-systems driving arrays of computing potentiometers; each array representing a parameter of attitude and motion of the aircraft and determining respectively simulated airspeed, pitch angle, attack angle, Mach number for the simulated flight conditions, roll angle, sideslip angle, altitude, and rate of climb for the prevailing control settings; the potentiometers having appropriately chosen laws and the servo-potentiometer systems having appropriately arranged mutual interconnections to compute the said parameters according to known aerodynamical laws whereby intermediate signals are generated to energize other servo-systems imposing the appropriate loading reactions upon the attitude controls and representative signals are generated effective to operate indicating instruments to simulate an aircraft compass, altimeter, attitude gyro, Mach number indicator, airspeed indi. cator, rate of climb indicator, ballbank indi. cator, engine tachometer, and engine manifold depression indicator according to the current control setting. A pupil-operated rudder control 325 (Fig. 4) is geared to deflect the sliders of lst and 2nd potentiometers, excited by antiphased airspeed (VT) signals from the output transformers of amplifiers 55 and 49 (Fig. 1) described below, and also driven by a retroactive biphase A.C. motorgenerator (FP) servo-system excited by amplifier 328 supplied with a degenerative rate signal from the generator; a trim signal from a potentiometer 332 which is centre tapped to earth, energized by antiphase airspeed (VT) signals from the output of amplifier 49 (Fig. 1) described below and adjusted by the rudder trim wheel 331; and a signal at terminal 322 representing the rudder reaction force, which is derived from the 13th potentiometer of the Mach (M) computing servo-system (Fig. 2) described below. The potentiometer voltages which are functions of airspeed (VT) and rudder deflection (Sp) are respectively applied to terminals 313, 321 to energize the 9th and 13th potentiometers of the Mach (M) computing servo-system (Fig. 2) for determination of rate of yaw (#z) and rudder loading (Fp) as described below, and the servosystem operates in a sense such as to reduce the resultant input voltage to zero to tend to neutralize the rudder control, and to resist its deflection by a force (Fp) which is a function of rudder displacement (#p), true airspeed (VT) and Mach number (M) in simulation of the aerodynamic loading experienced in an aircraft in flight. Pupil operated elevator and aileron controls 326,327 (Figs. 5, 6) similarly deflect the sliders of 1st and 2nd potentiometers energized by antiphase airspeed (VT) signals to derive signal functions of airspeed and elevator deflection (VT, #s) on terminals 311, 317, and signal functions of airspeed and aileron deflection (VT, #w) on terminals 308, 319 to respectively energize the 8th, 11th and 6th, 12th potentiometers of the Mach number (M) computing servo-system for determination of rate of pitch (Wy) and elevator loading, and roll factor and aileron loading respectively. The sliders and controls are also geared to respective A.C. retroactive motor-generator servo-systems excited by amplifiers 329, 330, which are responsive to signals from potentiometers 334, 336 energized by airspeed (VT) signals transformer coupled from amplifier 49 and operated by elevator and aileron trim wheels 333, 335, together with degenerative rate signals from the generators and signals at terminals 318, 320 representing the elevator and aileron reaction forces which are derived from potentiometers 11, 12 of the Mach (M) computing servo-system (Fig. 2) described below. The servo-systems operate in senses such as to reduce the respective resultant input voltages to zero to tend to neutralize the controls and to resist their deflection by forces (FS, FW) which are respectively functions of true airspeed (VT), Mach number (M) and elevator and aileron deflections (#s, #w) in simulation of the corresponding aerodynamic flight loading of the controls. Airspeed (VT) is computed in response to the pupil-operated throttle control (mechanically coupled to an engine manifold pressure indicator MAP) (Fig. 1) which varies a potentiometer 5 energized by a reference alternating voltage to develop a proportionate signal to excite a potentiometer 38, which is varied by a pupil operated engine speed control (mechanically coupled to a speed indicator TACH) to develop a signal proportionate to simulated engine power. The latter energizes the 3rd of a range of 8 potentiometers driven by the airspeed retroactive motor generator A.C. servo-system 21 excited by an amplifier 20 supplied with a retroactive rate signal from the generator, a thrust signal from the 3rd potentiometer, a drag signal on terminal 50 from the 3rd potentiometer of the Mach number (M) computing servo-system (Fig. 2) described below, a 1st resolved gravity signal on terminal 51 from the 3rd cosine potentiometer of the pitch angle (#) computing servo-system described below, and a 2nd resolved gravity signal on terminal 52 from the 5th potentiometer of the angle of attack (α) computing servo-system described below. The servo-system operates to reduce the resultant amplifier input to zero and drives the potentiometers through an angle proportional to the simulated computed true airspeed (VT) corresponding to the prevailing throttle engine speed, and aircraft attitude control settings. Pitch angle (6) is computed by retroactive A.C. motor-generator servo-system excited by amplifier 71, which is energized by a retroactive generator rate signal, a resolved vertical pitch rate signal on terminal 72 from the 4th cosine potentiometer of the roll angle (#) computing servo-system, and a resolved vertical yaw rate signal on terminal 74 from the 5th cosine potentiometer of the roll angle servo-system (Fig. 2) as described below. The servo-system operates to reduce the resultant amplifier input to zero and drive its associated 5 potentiometers through an angle proportional to the simulated pitch angle (#). Angle of attack (α) is computed by an A.C. motor-generator servo-system excited by amplifier 90 which is energized by a retroactive generator rate signal, a resolved pitch rate signal (wy) on terminal 91 from the output transformer of amplifier 104, a 1st resolved gravity signal on terminal 93 from the 2nd cosine potentiometer of the roll angle (#) computing servo-system, energized from the 2nd cosine potentiometer of the pitch angle (#) computing system, which is in turn energized by reciprocal airspeed 1/VT signals from the 5th and 6th potentiometers of the airspeed computing servo-system, a 2nd resolved gravity signal from the slider of the 4th potentiometer of the angle of attack computing servo-system, also energized from the 2nd potentiometer of the pitch angle servo-system. The input also receives a " lift " input signal from the 2nd potentiometer of the Mach computing servo-system, which is itself energized from the 1st empirical potentiometer of the angle of attack (α) computing servo-system, supplied with an altitude (h) signal from the phase-splitting output transformer of amplifier 157 of the altitude computing servo-system (Fig. 3) described below. The servo-system operates to zeroize the resultant input voltage and rotates the associated 7 potentiometers (of which the 1st and 2nd follow empirical laws) through an angle proportionate to the angle of attack α, and the 2nd potentiometer is energized on terminal 59, from the 2nd potentiometer of the airspeed (VT) computing servo-system through amplifier 49 and its phase-splitting output transformer, to produce an energizing signal for the 3rd potentiometer of the Mach number (M) computing servosystem from which a drag signal is derived for terminal 50 of the airspeed servo-system amplifier; while the 3rd (α) potentiometer is energized, on terminals 56, 57 through the phasesplitting output transformer of amplifier 55 with antiphase airspeed signal (VT) from the 1st potentiometer of the airspeed computing servosystem, to derive a pitch rate signal resolved from the angle of attack which in turn energizes over terminal 306 the 4th potentiometer of the Mach number computing servo-system whose output energizes the pitch rate (wy) signal amplifier 104 (Fig. 2) as described below. The 5th potentiometer is energized at terminals 96, 97 from the 3rd cosine potentiometer of the roll angle (#) computing servo-system (Fig. 2) itself energized over terminals 80, 81 from the 3rd cosine potentiometer of the pitch angle (#) computing servo-system (Fig. 1) which latter potentiometer also possesses a third slider on which appears the gravity signal applied to terminal 51 of the airspeed servo-system input amplifier. The 7th potentiometer is energized over terminals 98, 99 from a pair of ganged sliders of the 1st cosine potentiometer of the roll angle (#) computing servo-system (Fig. 2) to produce at terminal 100 an input voltage (representing the vertical component of airspeed) for the altitude (h) and rate of climb (dh/dt) computing servosystems (Fig. 3) described below. Mach number (M) is computed (Fig. 2) by an A.C. motor generator servo-sy