Date of Award


Document Type


Degree Name

Master of Science in Aeronautical Engineering


Department of Aeronautics and Astronautics

First Advisor

David R. Jacques, PhD

Second Advisor

Meir Pachter, PhD


Traditionally flight control systems have used linearized equations of motion solved around a single trim point. This thesis proposes a nested-loop controller directly solved from the equations of motion. The control equations were developed as a solution to asymmetrically trimmed flight conditions. A two-loop design was proposed for the controller. The outer loop modeled the aircraft as a point mass and all forces were balanced to find the aircraft states. The equations input the control variables and output the aircraft states. The inner-loop utilizes the six-degree of freedom model of the aircraft to solve the moment equations. With the input states, the required control surface deflections are calculated. The control equations were investigated for typical flight conditions to find the predicted aircraft control settings. The control equations were implemented using aeromodel data for a Learjet-25. The predictions from the control equations were then compared to flight test results. The model was able to predict the required elevator deflection for simple longitudinal cases in level and climbing flight to within tolerances. The simple lateral-directional cases were not as accurate as the longitudinal investigations. As complex maneuvers were investigated, the model predictions did not match the flight test results.

AFIT Designator


DTIC Accession Number