GB788608A - Improvements in or relating to aircraft - Google Patents

Abstract

788,608. Aircraft feel simulators. HOBSON, Ltd., H. M., SMITH, C. P., HULLEY, B. J., and PUGH, A. T. Oct. 26, 1955 [Dec. 7, 1954], No. 35409/54. Class 4. An aircraft fitted with power or servo-tab operated ailerons includes a feel simulator comprising a housing and a piston therein linked to a control column so as to be moved by departure of the column from neutral position, and means for establishing in the housing a hydraulic pressure opposing movement of the piston and increasing the pressure with increase in the rate of roll. In Fig. 1, the pilot's control stick 10 operates the ailerons 12 through servo-mechanism 13, 14, and is coupled to the piston 17 of a jack 16 pivoted to the aircraft, the jack containing fluid at a control pressure which offers resistance to the movement of the pilot's control stick from its neutral position. The control pressure fluid is supplied by a conduit 21 from a hydraulic valve block 22, supplied at a port 23 with fluid under pressure by a pump 25 and a reservoir 25<SP>1</SP> connected to an exhaust port 26 on the valve. Bob weights 49, 50 mounted on levers pivoted to the fuselage and connected by links 52, 53 to a lever 47 pivoted on the aircraft at 48, exert a torque on the lever proportional to the square of the rate of roll, due to centrifugal force. The lever 47 is also connected to a damper 55, and has an integral part 46 abutting a push rod 44. The hydraulic valve block 22, Fig. 2, comprises a valve 28 having lands 29, 30 and a waisted part 31 co-operating with a pressure part 23 an exhaust port 26, and a port 41 leading to the control pressure conduit 21. The control pressure acts on one end of valve 28 through a passage 34, and a spring 35 acts on the other end through a push rod 37 and a relief valve 38. The push rod 44 abuts a member 43 which forms one abutment for the spring 35, so that if the push rod is urged upwardly by the bob weights due to an increase in the rate of roll, the force of the spring is increased, and the valve 28 moves upwardly against the control pressure, placing the pressure port 23 in communication with the control pressure port 41, raising the control pressure until this is sufficient to return the valve 28 to its neutral position. Similarly a decrease in the rate of roll decreases the control pressure. The valve is also moved to allow fluid to flow into and out of the jack 15 as the pilot moves his control stick. Should the valve stick, the pilot can still move his stick, opening the relief valve to put the jack in communication with the exhaust port 26 through passage 40. Specification 734,437 is referred to.