Identification of Integrated Airframe–Propulsion Effects on an F-15 Aircraft for Application to Drag Minimization

Schkolnik, Gerard S. (1993) Identification of Integrated Airframe–Propulsion Effects on an F-15 Aircraft for Application to Drag Minimization. Technical Report NASA TM-4532, Research Engineering, NASA Dryden Flight Research Center.

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Abstract

The application of an adaptive real-time measurement-based performance optimization technique is being explored for a future flight research program. The key technical challenge of the approach is parameter identification, which uses a perturbation-search technique to identify changes in performance caused by forced oscillations of the controls. The controls on the NASA F-15 highly integrated digital electronic control (HIDEC) aircraft were perturbed using inlet cowl rotation steps at various subsonic and supersonic flight conditions to determine the effect on aircraft performance. The feasibility of the perturbation-search technique for identifying integrated airframe-propulsion system performance effects was successfully shown through flight experiments and postflight data analysis. Aircraft response and control data were analyzed postflight to identify gradients and to determine the minimum drag point. Changes in longitudinal acceleration as small as 0.004 g were measured, and absolute resolution was estimated to be 0.002 g or approximately 50 lbf of drag. Two techniques for identifying performance gradients were compared: a least-squares estimation algorithm and a modified maximum likelihood estimator algorithm. A complementary filter algorithm was used with the least squares estimator.

EPrint Type:	NASA Technical Memorandum
Keywords:	Adaptive control, Aircraft flight tests, Aircraft performance, Flight Optimization, Optimal control
Subjects:	Aircraft/Project: F-15 HIDEC (01 - 09) Aeronautics: (07) Aircraft Propulsion And Power (01 - 09) Aeronautics: (05) Aircraft Design, Testing And Performance
ID Code:	266
Deposited On:	23 July 2004
Additional Information:	27 pages. This paper was prepared as AIAA-93-3764 for the Guidance, Navigation, and Control Conference held August 9–11, 1993 in Monterey, California.