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Aviation History
1957
1957 - 1420.PDF
510 FLIGHT, 27 September 1957 RECORDING DESK OUST GENERATOR GUST FORCES CONTROL SURFACE ANGLES TWO NEW SIMULATORS . . . craft for which it was eventually intended,whether it be a high-speed fighter or large passenger airliner. As seen in the schematic diagram on thispage, the characteristic feature of the equip- ment is a gimbal-mounted table, themotion of which is controlled by three hydraulic servo-motors. On the table,which takes up an attitude corresponding to that of the aircraft, are mourned thegyroscopes and other instruments, their outputs being taken through slip-rings tothe central control device (perhaps most aptly described as the autopilot computer)and to a simulated blind-flying panel. The pilot's controls are coupled to the auto-pilot in the same way as in an aircraft, and control of the hydraulic actuators may beexercised electrically or by mechanical linkage as selected by the operator. The hydraulic actuators drive loadswhich are adjusted to have the same aero- elastic properties as the actual control sur-faces would have on a full-scale aircraft. To each control surface there is coupled apotentiometer from which voltages propor- tional to the control-surface angles arederived. These, together with signals from a gust generator, are fed into the input ofan analogue computer; while the aero- dynamic derivatives of the aircraft undertest are set in on the panels of the com- puter. From the combination of control-surface angles and gusts fed in, the attitude of the aircraft is computed continuouslyas three voltages which are used to drive the three servo-motors on the gimbal table,thereby closing the simulation loop. Other outputs of the analogue computerare height and airspeed, which are used to drive the small servo-motors geared tothe instrument panel and to the barometric capsules in the autopilot computer. Fur-ther signals are Mach number and turn-and-slip signals for the instrument panel. A recording disc with six pen recorders anda twelve-channel photographic recorder is also provided. The control system itself is designed as a fully integratedsystem to combine the facilities of autopilot, autostabilizer and electro-hydraulic power-operated controls in one comprehensiveequipment. By integrating the three services, and thus avoiding unnecessary duplication of components, considerable simplifica-tion and weight-saving has been achieved. Reduction in weight follows automatically.The autopilot computer, which embodies complete transistor- ization and the use of printed-circuit techniques, performs thefunction of autopilot and autostabilizer according to which mode of control is selected. It receives signals from three rate-gyros and from airspeed and altitude sensers and a lateral accelero- meter mounted in the fuselage. A master reference gyro providesheading and pitch and roll angle signals; in addition, demand signals from the pilot's manual controls can also be fed into thesystem. The autopilot computer then sends out suitable signals to the hydraulic actuators which impart the appropriate move-ment to the control surfaces. Four different control modes are available: "Direct"(mechanical), "Autostabilizer," "Rate Control" and "Autopilot." GIMBAL SERVOS MASTER REFERENCE AND RATE GYROS MOVING TABLE AERODYNAMIC COMPUTER COMPASS ACCELERATION ERRORS HEIGHT AND AIRSPEED MACHB N TTURN& SLIP ETC PILOTS INSTRUMENT PANEL J AILERON IACTUATORS ELEVATOR ACTUATOR RUDDER ACTUATOR MANUAL CONTROLS TRIM AND FEEL LITTLE STICTT" ELECTRIC SIGNALLING SIGNALS FROM TABLE GIMBAL SERVOMOTOR FLUX VALVE SIMULATOR AUTOPILOT COMPUTER The Sperry control simulator in block diagram form, showing the various control loops for manual, stabilization and autopilot control modes, together with the gimbal-mounted attitude reference system (shown semi-pictorially at top right). Facilities for reversion to direct mechanical control are providedfor use in emergency in the event of electrical power failure. For the "Rate Control" mode, a separate miniature stick has been pro-vided, as it was felt that having two significantly different control modes on the main control column might be disconcerting forthe pilot. Movement of the miniature stick, it is stated, will automatically result in perfectly co-ordinated flight manoeuvres,the necessary control-surface angles being automatically and continuously applied by the autopilot computer. The rudderpedals are used solely to produce side-slip if required, the basic rudder control signals in turns emanating primarily from thelateral accelerometer. The aircraft is flown entirely with the miniature stick. Facilities available in the "Auto-pilot" mode include headingselection, Mach lock, height lock, flight-director coupling, I.L.S. coupling and coupling to weapons system. When "Autopilot" isselected, the aircraft will maintain the flight path it was following at the instant of engagement until a change is introduced by meansof the trimming knobs. Current design-studies for the new equipment include theinvestigation of its suitability for application to large helicopters. As a result of tests already completed, the manufacturers claima high degree of accuracy and reliability for the equipment. COVENTRY VICTOR FLYING NEPTUNE ON show to the general public for the first time, the FlyingNeptune engine, built by the Coventry Victor Motor Com- pany, Ltd., is a feature of the Popular Flying Association standsat the Arts and Handicrafts Exhibition which closes at Earl's Court, London, tomorrow.The Flying Neptune is a conversion of the Neptune flat four industrial engine. The aircraft version was first subjected to a50 hr test in a Piper Cub at Southend; and was flown at that time by Flight's representative Flight for July 15, 1955). It is a flat-four, air-cooled unit, with wet sump lubrication, overhead valves and a capacity of 1,815 c.c; and it gives 55-60 h.p. at 3,200 r.p.m.Bore and stroke are respectively 85 mm and 80 mm; and weight is about 210 lb. Continuous cruising power is 44 b.h.p. at2,600 r.p.m. The combustion chambers are hemispherical and the valves are inclined—a feature which is largely responsiblefor the especially good fuel consumption of 0.45 pt/bJi.p./hr. A twin-magneto ignition system has now been fitted.The Flying Neptune is remarkable for its smooth running and good throttle response; and one example has given excellent resultswhen installed in a Turbi. It takes both prolonged running at full throttle and long climbs in its stride. The engine was con-verted as a personal private venture by Maj. W. A. Weaver, managing director of the Coventry Victor Motor Co. SIDE-LOOKING, 3-COLOUR RADAR A CONTRACT worth $1.4m (approximately £499,998) hasbeen awarded to Texas Instruments, Inc., for a sideways- looking airborne radar which produces a three-dimensional, con- tinuous picture in three colours of the ground over which an aircraft is flying. The new equipment uses transistors instead 01 valves where possible.
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