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Airframes and systems - part 3

Các tọa độ nút 1 / 4 của khung được đưa ra trong Bảng P.12.5 (i). Trong cấu trúc này biến dạng của mỗi thành viên là do một hiệu ứng duy nhất, trục được, uốn cong hoặc xoắn. Các chế độ biến dạng của mỗi thành viên được đưa ra trong Bảng P. | LANDING GEAR SYSTEMS LANDING GEAR 1.5 CONSTRUCTION OF OLEO-PNEUMATIC STRUTS. Figure 1.1. shows the construction of a simple oleo-pneumatic strut in this instance a nose undercarriage which also includes a steering mechanism. The outer cylinder is fixed rigidly to the airframe structure by two mounting brackets and houses an inner cylinder and a piston assembly the interior space being partially filled with hydraulic fluid and inflated with compressed gas air or nitrogen . The inner cylinder is free to rotate and move up and down within the outer cylinder but these movements are limited by the torque links which connect the inner cylinder to the steering collar. The steering collar arms are connected through spring struts to the rudder pedals and a shimmy damper is attached to the steering collar. 1.6 OLEO-PNEUMATIC STRUT OPERATION. a Under static conditions the weight of the aircraft is balanced by the strut gas pressure and the inner cylinder takes up a position approximately midway up its stroke. b Under compression e.g. when landing the strut shortens and fluid is forced through the gap between the piston orifice and the metering rod this restriction limiting the speed of upward movement of the inner cylinder. c As the internal volume of the cylinders decreases the gas pressure rises until it balances the upward force. d As the upward force decreases the gas pressure acts as a spring and extends the inner cylinder. The speed of extension is limited by the restricted flow of fluid through the orifice. e Normal taxying bumps are cushioned by the gas pressure and dampened by the limited flow of fluid through the orifice. f Movement of the rudder pedals turns the nose wheel to facilitate ground manoeuvres the spring struts being provided to allow for vertical movement of the nose wheel and prevent shocks from being transmitted through the rudder control system. NOTE Evidence of strut gas pressure leakage will be given by the strut not extending as far as it should .