Marc Roy

Date of Award

11-1990

Document Type

Thesis

Degree Name

Master of Science in Aeronautical Engineering

Department

Department of Aeronautics and Astronautics

First Advisor

Curtis Mracek, PhD

Abstract

An investigation was performed to analyze the dynamic stability characteristic of an aircraft which has sustained damage to a primary control surface. The analysis was performed using the existing functional form of actual wind tunnel data taken on an F-16 model. Two control schemes are used for trimming an F-16 that has sustained damage to its rudder. The first control scheme represent the basic aircraft, while the second allowed the horizontal tail ailerons to move independently from the flaperons. The investigation was conducted for one flight condition representative of the aircraft at cruise speed. Region in α/β (angle of attack)/(sideslip angle) space where trim can be achieved was selected as input into a linearized aircraft model. This model took into account the failed control surface. Eigenvalues of the open and closed loop models were analyzed to determine the region in alpha/beta space where the aircraft was dynamically stable. Migration of the eigenvalues for several trim conditions was also investigated to gain insight on the aircraft behavior while in an unsymmetrical orientation. For this study, the open loop eigenvalues for the trim are investigated gave a stable system. When the aircraft controller was added into the system, regions of dynamic instability appeared. For rudder failure less than -20 degrees, trim could be achieved but the aircraft was dynamically unstable.

AFIT Designator

AFIT-GAE-ENY-90D-24

DTIC Accession Number

ADA230517

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