Dynamic Stability and Handling Qualities of Small Unmanned-Aerial-Vehicles UNMANNED ...

140 Pages·2016·3.05 MB·English

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Theses and Dissertations
2004-12-07
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Tyler Michael Foster
Brigham Young University - Provo
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Foster, Tyler Michael, "Dynamic Stability and Handling Qualities of Small Unmanned-Aerial-Vehicles
UNMANNED-AERIAL-VEHICLES" (2004). Theses and Dissertations. 219.
https://scholarsarchive.byu.edu/etd/219
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DYNAMIC STABILITY AND HANDLING QUALITIES OF SMALL
UNMANNED-AERIAL-VEHICLES

by
Tyler M. Foster

A thesis submitted to the faculty of
Brigham Young University
in partial fulfillment of the requirements for the degree of

Master of Science

Department of Mechanical Engineering
Brigham Young University
April 2005
Copyright © 2005 Tyler M. Foster
All Rights Reserved
BRIGHAM YOUNG UNIVERSITY

GRADUATE COMMITTEE APPROVAL

of a thesis submitted by

Tyler M. Foster

This thesis has been read by each member of the following graduate committee and by
majority vote has been found to be satisfactory.

_______________________________ ____________________________________
Date W. Jerry Bowman, Chair

_______________________________ ____________________________________
Date Timothy W. McLain

_______________________________ ____________________________________
Date Jeffrey P. Bons
BRIGHAM YOUNG UNIVERSITY

As chair of the candidate’s graduate committee, I have read the thesis of Tyler M. Foster
in its final form and have found that (1) its format, citations, and bibliographical style are
consistent and acceptable and fulfill university and department style requirements; (2) its
illustrative materials including figures, tables, and charts are in place; and (3) the final
manuscript is satisfactory to the graduate committee and is ready for submission to the
university library.

_______________________________ ____________________________________
Date W. Jerry Bowman
Chair, Graduate Committee

Accepted for the Department

____________________________________
Matthew R. Jones
Graduate Coordinator

Accepted for the College

____________________________________
Douglas M. Chabries
Dean, Ira A. Fulton College of Engineering
and Technology
ABSTRACT

DYNAMIC STABILITY AND HANDLING QUALITIES OF SMALL

UNMANNED-AERIAL-VEHICLES

Tyler M. Foster

Department of Mechanical Engineering

Master of Science

General aircraft dynamic stability theory was used to predict the natural
frequencies, damping ratios and time constants of the dynamic modes for three specific
small UAVs with wingspans on the scale from 0.6 meters to 1.2 meters. Using USAF
DatCom methods, a spreadsheet program for predicting the dynamic stability and
handling qualities of small UAVs was created for use in the design stage of new small
UAV concept development. This program was verified by inputting data for a Cessna-
182, and by then comparing the program output with that of a similar program developed
by DAR Corporation. Predictions with acceptable errors were made for all of the
dynamic modes except for the spiral mode. The design tool was also used to verify and
develop dynamic stability and handling qualities design guidelines for small UAV
designers.
Using this design tool, it was observed that small UAVs tend to exhibit higher
natural frequencies of oscillation for all of the dynamic modes. Comparing the program
outputs with military handling qualities specifications, the small UAVs at standard
configurations fell outside the range of acceptable handling qualities for short-period
mode natural frequency, even though multiple test pilots rated the flying qualities as
acceptable. Using dynamic scaling methods to adjust the current military standards for
the short period mode, a new scale was proposed specifically for small UAVs. This scale
was verified by conducting flight tests of three small UAVs at various configurations
until poor handling qualities were observed. These transitions were observed to occur at
approximately the boundary predicted by the new, adjusted scale.
ACKNOWLEDGEMENTS

I would like to thank Dr. Jerry Bowman for his patience, understanding and
assistance with this project. His engineering insight and experience were invaluable as I
thought through the research and presentation of this project. Had I been in his shoes, I
think I might have given up on me a long time ago! I would like to acknowledge the
diligent efforts of Nathan Knoebel in helping me at the beginning of this project. I would
also like to thank my family for their continued love and support even as my graduate
work seemed to drag on and on. Most of all and especially I want to express my
gratitude to my lovely fiancée, Danalin. I love her more than I have ever loved anyone or
anything in my lifetime. As this project drew to a close and the hours spent away from
her steadily increased, her expressions of love and support kept my confidence up, my
morale high and my courage alive.

Table of Contents

CHAPTER 1 ............................................................................................1
Introduction to the Problem of Unstable UAVs.................................................................................1
1.1 Unstable Airplanes Aren’t Much Fun!.....................................................................................1
1.2 The Objective of This Thesis.....................................................................................................3
1.3 The Small UAVs To Be Studied................................................................................................4
1.4 Literature Review.......................................................................................................................6
1.5 Brief Overview of Chapters.......................................................................................................8
CHAPTER 2 ..........................................................................................11
Static and Dynamic Stability of Fixed-Wing Aircraft.....................................................................11
2.1 Stability: A Requirement for All Airplanes...........................................................................11
2.2 Static Stability...........................................................................................................................13
2.3 Dynamic Stability.....................................................................................................................18
2.4 Longitudinal Dynamic Stability..............................................................................................20
2.5 The Short Period and Phugoid Approximations...................................................................25
2.6 Lateral-Directional Dynamic Stability...................................................................................28
2.7 The Spiral, Roll and Dutch-Roll Approximations.................................................................31
2.8 Dynamic Modes For Small UAVs...........................................................................................34
CHAPTER 3 ..........................................................................................39
Handling Qualities...................................................................................................................................39
3.1 What Are Handling Qualities?................................................................................................39
3.2 Handling Qualities for Conventional Aircraft.......................................................................40
3.3 Handling Qualities Are Related to the Dynamic Modes.......................................................42
3.4 Handling Qualities for Small UAVs........................................................................................48
CHAPTER 4 ..........................................................................................51
Methods for Predicting Dynamic Stability........................................................................................51
4.1 Predicting the Dynamic Stability of Small UAVs..................................................................51
4.2 Dynamic Modes Predictor.......................................................................................................52
4.3 Verification of Model...............................................................................................................53
4.4 Predictions for Three Small UAVs.........................................................................................58
CHAPTER 5 ..........................................................................................63
Handling Qualities Standards for Small UAVs.................................................................................63
5.1 New Handling Qualities Standards Needed For Small UAVs..............................................63
5.2 Higher Natural Frequencies of Oscillation for Small UAVs.................................................63
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