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AssigneeThe United States of America as represented by the Administrator of the National Aeronautics and Space Administration
InventorGlenn B. Gilyard
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Practical application of real-time (or near real-time) Adaptive Performance Optimization (APO) is provided for a transport aircraft in steady climb, cruise, turn descent or other flight conditions based on measurements and calculations of incremental drag from a forced response maneuver of one or more redundant control effectors defined as those in excess of the minimum set of control effectors required to maintain the steady flight condition in progress. The method comprises the steps of applying excitation in a raised-cosine form over an interval of from 100 to 500 sec. at the rate of 1 to 10 sets/sec of excitation, and data for analysis is gathered in sets of measurements made during the excitation to calculate lift and drag coefficients C.sub.L and C.sub.D from two equations, one for each coefficient. A third equation is an expansion of C.sub.D as a function of parasitic drag, induced drag, Mach and altitude drag effects, and control effector drag, and assumes a quadratic variation of drag with positions .delta..sub.i of redundant control effectors i=1 to n. The third equation is then solved for .delta..sub.iopt the optimal position of redundant control effector i, which is then used to set the control effector i for optimum performance during the remainder of said steady flight or until monitored flight conditions change by some predetermined amount as determined automatically or a predetermined minimum flight time has elapsed.
A method for providing in-flight adaptive performance optimization of an aircraft in a steady climb, cruise, turn or descent flight condition that uses autopilot and navigation modes in a normal manner or by the pilot's direct control, where said optimization is based on real-time measurements and calculations of incremental drag from a forced response maneuver of one or more redundant control effectors that affect aircraft drag defined as those control effectors that are in excess of the minimum set of control effectors that affect aircraft drag required to maintain said steady flight condition in progress, comprising the steps of first applying excitation to said one or more redundant control effectors simultaneously in a smooth raised-cosine form over a finite interval, concurrently gathering sets of measurements made during said excitation, next calculating lift and drag coefficients C.sub.L and C.sub.D from two equations, one for each coefficient, and then calculating an optimum position .delta..sub.iopt of said one or more redundant control effectors from a third equation which is an expansion of C.sub.D as a function of parasitic drag, induced drag, Mach, altitude drag effects, and control effector drag, said third equation comprising a quadratic variation of drag with positions .delta..sub.i of redundant control effectors i=1 to n, solving said third equation for .delta..sub.iopt in a separate step, and finally using the value .delta..sub.iopt to set the position of each control effector i for optimum performance of said aircraft throughout the remainder of said steady flight condition, unless monitored flight conditions change by some predetermined minimum amount, or a predetermined minimum flight time lapses, or flight conditions have changed an amount perceptible by a flight crew monitoring instruments in the cockpit of said aircraft, in response to any one of which occurs, said method for providing in-flight adaptive performance optimization is repeated.
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