GB855573A - Multiple lift aircraft engine instrumentation - Google Patents

Abstract

855,573. Displaying multiple signals; controlling aircraft engines. ROLLS-ROYCE Ltd. March 2, 1959 [April 3, 1958], No. 10802/58. Class 40 (1). [Also in Groups XXXIII and XXXVI] A vertical take - off aircraft multi-engine installation includes a device which transmits from each engine a signal representative of an engine variable and comparator means to receive the signals and thereby indicate and/ or control the engine operating conditions. The comparator means may be a visual indicator in which the variables are viewed simultaneously or sequentially in comparison with an average signal or a reference signal, or may be an electrical device for indicating or controlling when the signal from an engine differs by a predetermined amount from an average or reference signal. The engine operating condition sensed may be rotational speed, jet-pipe temperature, jet-pipe total head pressure, or the ratio between the compressor and turbine outlet pressures. In Fig. 1, fiftysix engines 10 in four banks of fourteen each pass a signal to cathode-ray tubes 12 where they are displayed simultaneously, the average value of each bank being shown on a mechanical indicator 13. Each line on the tube can be displayed next to a " ghost " line representing a reference value (Fig. 1A, not shown). Alternatively (Fig. 2, not shown), each signal is compared with a reference signal and one of a bank of fifty-six lamps will fail to light if the corresponding signal deviates from a predetermined tolerance. The indicator board contains a set of push-buttons to shut-off an engine if it is faulty. In Fig. 3, each gas-turbine engine has a pressure transducer 25a in the jet pipe and a throttle control 27 which, by means of a potentiometer, generates a signal representing the desired throttle position for the engine. The pressure signals are presented sequentially by means of a switch 33 to a comparator 32 and if they differ from the command signal by more than a certain amount (in either sense) the tolerance circuit 36 energizes a relay 38. The difference signal then passes via contact 39 and switch 41 to a solenoid 44 which operates a shut-off cock 24 in the fuel line to the engine. Closure of this cock lights an indicator lamp (not shown) and energizes a bridge circuit 50 via line 46. The outputs of the bridge circuits are added together and when the total output is large enough (e.g. when three engines have been cut off) a bi-stable polarized relay operates to open the contact 39 and prevent any more engines from being shut off. A differentiating circuit is included in the comparator 32 so that the shut-off arrangements will not operate when a change in thrust is called for by the pilot, i.e. during controlled acceleration or deceleration of the engine bank. Fig. 4 (not shown) contains the detailed circuitry of the arrangement of Fig. 3. In Figs. 5 and 6 (not shown) the individual signals from the engines are compared sequentially with the average of all the signals and the difference signal used to shut-off the corresponding engine if it exceeds a predetermined amount. The comparison is effected by means of a feed-back amplifier. Specification 821,544 is referred to.