GB1241986A - Flight attitude control system for multiple-engined vertical take-off and landing aircraft - Google Patents

Abstract

1,241,986. Flight attitude central system. VEREINIGTE FLUGTECHNISCHE WERKE-FOKKER G.m.b.H. 22 Aug., 1968 No. 40264/68. Heading B7G. A flight attitude control system for a vertical take-off and landing aircraft with engines off-set from the centre of gravity, and flight attitude control nozzles which can be actuated by a flight attitude regulator or by the control column, comprises first flight attitude control nozzles 4, 5 from which a steady stream of compressed air may be blown out continuously and which are controlled differentially, second flight attitude control nozzles from which compressed air may be blown out only intermittently and a thrust modulation device 23 for varying differentially the thrust of the engines. The system is such that to compensate for small irregularities in attitude the first nozzles may immediately blow out compressed air from those parts of the engine from which air may be bled continuously but that for major faults of long duration, such as an engine cutting out, compressed air may be blown out from those parts of the engines from which air may be bled only intermittently and then thrust modulations may be employed. An input from the control column or the attitude gyros to the flight attitude regulator 1 is transmitted by a servomotor 2 to a link valve with three control slots 3, 6, 8. The first slot 3 acts immediately to control the first downward blast nozzles 4, 5 by a valve 21, and then slot 6 coupled to slot 3 and with a lost motion may open either the upward or downward nozzle 7 for " intermittent " air, but, due to the lost motion, only in the case of major signals from the flight attitude regulator 1. The thrust modulation device 23 owing to its lost motion and a delay element 9, only becomes effective in the case of major signals of long duration. In an alternative arrangement, Fig. 2b (not shown), the link (6<SP>1</SP>) controlling the nozzle 7, is coupled to the thrust modulation linkage 23 after the delay element 9 so that the intermittent compressed air and the thrust modulation intervene jointly only after major faults of long duration. The system may be also electrical, Fig. 4 (not shown), or hydraulic, Fig. 5 (not shown). In the latter the delay element is an hydraulic servo element (24) which has a servo valve with the characteristic that it delivers very small flow quantities for small signals and very large quantities for large signals, so that small signals are executed very slowly and large signals very rapidly.