Aircraft arresting system

An apparatus for controlling the rate of deceleration of a moving body comprising:

• engaging means operatively engageable with said moving body;
• flexible means connected to said engaging means, said flexible means being wound onto a real means at the start of a deceleration and being unwindable from said reel during said deceleration so that unwinding said flexible means from said reel causes a corresponding rotation of said reel;
• pumping means having an inlet and a discharge, said pumping means being operatively connected to said reel means so that rotation of said reel means causes pumping of a hydraulic fluid through said pumping means at a rate which increases as the rate of rotation of said reel increases;
• control valve means operatively disposed across the discharge of said pumping means for varying pressure drop across said control valve;
• braking means for applying a braking force to said reel;
• means responsive to the pressure drop across said control valve for varying the braking force applied by said braking means;
• means for, at frequent intervals during a deceleration, generating a signal which is representative of the total linear length L that said flexible means has been unwound from said reel from the start of said deceleration to a particular time;
• means for, a frequent intervals during a deceleration, generating a signal which is representative of the linear velocity V at which said flexible means is being unwound from said reel at said particular time;
• means for at frequent intervals during a deceleration, controlling actual flow rate FA through said control valve such that the value of FA divided by the value of V is approximately equal to the value of R at said particular time during a deceleration, where R is a numerical ratio the value of which varies with the linear length of the flexible means which has been unwound and providing a braking force which is optimal for the apparatus and the moving body engaged thereby.