GB1304014A - - Google Patents

Abstract

1304014 Aircraft indicators ELLIOTT BROS (LONDON) Ltd 21 April 1970 [21 April 1969 22 Aug 1969] 20301/69 and 41931/69 Heading B7W An indicator for indicating to a pilot of a helicopter the reserve margin of lift available under given operating conditions comprises scales 11A and 11B graduated in divisions of tens of horsepower, a first marker symbol index 13A carried by a ribbon 14A and a second index 13B, graduated in tens of horsepower, carried by a ribbon 14B. The index 13A and its scale 11A indicate the power available at the helicopter rotor under present ambient temperature and pressure conditions and engine shaft speed, and index 13B and its scale 11B indicate the power presently consumed by the rotor whilst the relative position of the two indices 13A, 13B represents the margin of power available. A trimming control 20 is provided to enable the correct relationship between indices 13A and 13B to be maintained. A further symbol 15, associated with scale 13B, indicates a power transmission limit which the drive from the engine to the rotor should not exceed. Each ribbon 14A, 14B is driven by a servo mechanism as shown in Fig. 6, and a tapping is taken from the output of each amplifier 16 to a monitoring circuit 40, and a spring-biased flag 22 whereby in the event of de-energization of the circuit a striped portion of the flag becomes visible (Fig. 1). The servo driving ribbon 14A is energized by a signal Pa, Fig. 2, representing maximum power available from the engine, derived by a computer 17 having inputs T, S, NC 1 and NC 2 , respectively, representing ambient atmospheric absolute temperature, ambient static pressure and present engine speeds of two engines driving the rotor. The servo driving ribbon 14B is energized by a signal P c , Fig. 2, representing power consumed by the rotor, derived by a computer 19 having inputs C and # representing respectively rotor torque and rotor speed.