Date of Award

9-2020

Document Type

Thesis

Degree Name

Master of Science

Department

Department of Aeronautics and Astronautics

First Advisor

Donald L. Kunz, PhD

Abstract

A dynamic helicopter model was incorporated into an optimal control problem to determine minimal landing velocities. The solutions were determined using pseudospectral collocation methods as implemented by the GPOPS-II software. These solutions were then compiled to develop a HV diagram. An HV diagram displays regions of flight based on a helicopter's airspeed and height above the ground in which a safe landing would not be possible following engine failure. The applied methodology for constructing the HV diagram reduced issues involving solution convergence that was encountered in previous research. The influence of ground effect on the dynamic model was also investigated. After analyzing the HV diagrams constructed using five additional ground effect models, the significant impact that a chosen ground effect model has in the overall dynamic model was apparent. Finally, the effect that modifying certain helicopter parameters has on the helicopter's autorotation performance was considered. Optimal control solutions showed a decrease in autorotation capabilities for the case of an increased gross weight as well as for the case of a decreased rotor size.

AFIT Designator

AFIT-ENY-MS-20-S-084

DTIC Accession Number

AD1110966

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