Date of Award

3-2005

Document Type

Thesis

Degree Name

Master of Science

Department

Department of Aeronautics and Astronautics

First Advisor

Richard G. Cobb, PhD

Abstract

This work investigates another way of contributing to the radar minimization solution for air vehicles in a threat environment. While much research has been conducted on structural solutions to radar exposure minimization, not much work has been done in the area of using control to continuously assess and present the smallest radar cross section of an air vehicle to oncoming threat radar systems by changing the aircraft's orientation. This work looks at the application of sideslip/beta angle feedback control of an unmanned helicopter to minimize radar cross section exposure in a hostile radar environment. A new way of controlling aircraft trajectory is introduced that incorporates both path and orientation optimization feedback; the aircraft's heading is controlled to orient the vehicle in a way that reduces its radar cross section, while sideslip angle is used to control the aircraft's path. A representative hostile environment is created and results show that a substantial reduction in radar cross section exposure can be achieved with beta feedback control. A linear state space model is derived for the OH-6A helicopter with the JANRAD software program. Eigenstructure assignment is used to shape the response of the helicopter into desired response modes. A Matlab based flight control system is developed around the derived helicopter model with altitude, heading, and beta angle command signals that drive four conventional helicopter control inputs.

AFIT Designator

AFIT-GAE-ENY-05-M26

DTIC Accession Number

ADA434892

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