Automatic trimming systems for the control surfaces of a moving craft

Claim 1

AN AUTOMATIC TRIMMING SYSTEM FOR A CONTROL SURFACE MEANS OF A MOVING CRAFT COMPRISING A DETECTOR RESPONSIVE TO OUT OF TRIM CONDITIONS ABOUT THE AXIS ABOUT WHICH SAID CONTROL SURFACE MEANS CAUSE ROTATION OF THE CRAFT, THE DETECTOR HAVING A FIRST STATE CORRESPONDING TO NO APPRECIABLE OUT OF TRIM AND SECOND AND THIRD STATES RESPECTIVELY CORRESPONDING TO APPRECIABLE OUT OF TRIM OF THE CRAFT IN OPPOSITE SENSES ABOUT SAID AXIS, FIRST AND SECOND SIMILAR INDEPENDENT CHANNELS WITH INPUTS CONTROLLED BY THE DETECTOR, THE CHANNELS BOTH PRODUCING ZERO OUTPUT WHEN THE DETECTOR IS IN ITS FIRST STATE AND, WHEN THE DETECTOR IS IN EITHER OF ITS SECOND AND THIRD STATES, OUTPUTS WHICH ARE SUBSTANTIALLY EQUAL IN MAGNITUDE AND OF THE SAME SENSE WHICH SENSE CHANGES ACCORDING AS TO WHETHER THE DETECTOR IS IN ITS SECOND OR ITS THIRD STATE, MEANS FOR COMBINING THE OUTPUTS OF THE TWO CHANNELS ALGEBRAICALLY TO PRODUCE A COMBINED OUTPUT SIGNAL AND POSITIONABLE MEANS ASSOCIATED WITH THE CONTROL SURFACE MEANS TO CORRECT OUT OF TRIM CONDITIONS ABOUT SAID AXIS, AND MEANS FOR APPLYING SAID COMBINED OUTPUT SIGNAL TO SAID POSITIONABLE MEANS TO CAUSE IT TO BE MOVED AT A RATE PROPORTIONAL TO THE MAGNITUDE OF THE COMBINED OUTPUT SIGNAL AND IN A SENSE TO CORRECT ANY OUT OF TRIM CONDITION.