Brigham Young University BYU ScholarsArchive Theses and Dissertations 2004-12-07 Dynamic Stability and Handling Qualities of Small Unmanned- Aerial-Vehicles UNMANNED-AERIAL-VEHICLES Tyler Michael Foster Brigham Young University - Provo Follow this and additional works at: https://scholarsarchive.byu.edu/etd Part of the Mechanical Engineering Commons BYU ScholarsArchive Citation 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 This Thesis is brought to you for free and open access by BYU ScholarsArchive. It has been accepted for inclusion in Theses and Dissertations by an authorized administrator of BYU ScholarsArchive. For more information, please contact [email protected], [email protected]. 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 ix 5.3 Rating Handling Qualities for Small UAVs Using Current Military Standards ............... 68 5.4 New UAV Handling