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INFORMATION TO USERS This manuscript has been reproduced from the microfilm master. UMI films the text directly from the original or copy submitted. Thus, some thesis and dissertation copies are in typewriter face, while others may be from any type of computer printer. The quality of this reproduction is dependent upon the quality of the copy submitted. Broken or indistinct print, colored or poor quality illustrations and photographs, print bleedthrough, substandard margins, and improper alignment can adversely affect reproduction. In the unlikely event that the author did not send UMI a complete manuscript and there are missing pages, these will be noted. Also, if unauthorized copyright material had to be removed, a note will indicate the deletion. Oversize materials (e.g., maps, drawings, charts) are reproduced by sectioning the original, beginning at the upper left-hand comer and continuing from left to right in equal sections with small overlaps. Each original is also photographed in one exposure and is included in reduced form at the back of the book. Photographs included in the original manuscript have been reproduced xerographically in this copy. Higher quality 6” x 9” black and white photographic prints are available for any photographs or illustrations appearing in this copy for an additional charge. Contact UMI directly to order. UMI A Bell & Howell Information Company 300 North Zed) Road, Ann Aitx>r MI 48106-1346 USA 313/761-4700 800/521-0600 A NONLINEAR AIRCRAFT SIMULATION OF ICE CONTAMINATED TAILPLANE STALL DISSERTATION Presented in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy in the Graduate School of The Ohio State University By Dale W. Hiltner, B.S., M.S ***** The Ohio State University 1998 Dissertation Committee: Approved by Professor Gerald M. Gregorek, Adviser Professor Rama. K. Yedavalli Professor Hayrani Oz i ‘ Advise] Aeronautical and Astronautical Engineering Graduate Program UMI Number: 99 00844 Copyright 19 9 8 by Hiltner, Dale William All rights reserved. UMI Microform 9900844 Copyright 1998, by UMI Company. All rights reserved. This microform edition is protected against unauthorized copying under Title 17, United States Code. UMI 300 North Zeeb Road Ann Arbor, MI 48103 Copyright by Dale W. Hiltner 1 9 9 8 ABSTRACT The effects of tailplane icing on the flight dynamics of the NASA Lewis Research Center DHC-6 Twin Otter research aircraft have been analyzed using a specialized nonlinear simulation program. The program performed the integration of standard aircraft equations of motion with aircraft characteristics determined from tables and functions. For this research, a specialized database based on flight test and wind tunnel test data was developed. Unique methods were used to separate the tailplane contribution from the aircraft characteristics to create this database and separately model the wing/body and tailplane aerodynamic characteristics of the DHC-6 Twin Otter aircraft. A pilot model and a reversible control system model tailored for this research were effective in assessing the effects of tailplane icing. Tailplane angle-of-attack showed trends of decreasing with decreasing airspeed and decreasing pitch rate during pushover maneuvers. At trim flight conditions, tailplane angle-of-attack was shown to decrease with increasing airspeed and increasing flap deflection. All of the pushover maneuvers to zero g load factor with non-zero flap 11 deflections and the iced tailplane model showed a tendency for control difficulties. The simulation responses were shown to be slightly conservative in predicting tailplane stall flight conditions compared to flight test data. The simulation program responses suggest that a discriminator of susceptibility to ice contaminated tailplane stall for the DHC-6 Twin Otter is a pushover maneuver through a load factor of nz=0. 5g with no significant stick force lightening, no tendency for a divergent load factor or pitch rate, and positive control of the maneuver. The responses showed that tailplane icing causes two distinct stability and control problems; inadequate flying qualities if the tailplane angle-of-attack exceeds that of the hinge moment break, and reduced stability when the tailplane is near the stalling angle-of-attack. A novel V-n diagram limited by tailplane stall angle-of-attack was useful in quantifying these maneuvering limitations caused by tailplane icing across the flight envelope. Ill Dedication To all those pilots and passengers flying into dark and stormy winter skies. IV ACKNOWLEDGMENTS I wish to chank the NASA Lewis Research Center Icing Technology Branch for providing the funding to support this effort. I also wish to thank all those friends and acquaintances who have put up with my unique personality during the course of this effort. Especially Dr. Michael J. Flanagan and his wife Stephanie, without whose support and advice I would not have finished this endeavor. VITA April 17, 1956 ............... Born - Dover, Ohio 1978 ....................... B.S. Aeronautical and Astronautical Engineering, The Ohio State University 1983 ....................... M.S. Aeronautics and Astronautics, M.I.T. 1978-1991 ................... Engineer McDonnell Aircraft Co. St. Louis, MO 1991-1996 ................... Graduate Research Assistant, Department of Aeronautical and Astronautical Engineering, The Ohio State University Columbus, Ohio 19 96-Present ................. Engineer, Aerodynamics Stability and Control Boeing Seattle, WA FIELDS OF STUDY Major Field: Aeronautical and Astronautical Engineering VI TABLE OF CONTENTS A b s t r a c t .................................................. ii D e d i c a t i o n ...............................................iii Acknowledgments........................................... iv V i t a ................................................... V LIST OF TABLES ........................................... ix LIST OF FIGURES ......................................... x LIST OF SYMBOLS ........................................... xv 1. INTRODUCTION AND BACKGROUND ....................... 1 1.2 Ice Contaminated Tailplane Stall Background . 2 1.3 Research Approach ............................ 7 2 . PRIOR STUDIES OF TAILPLANE I C I N G ................. 13 2.1 Wind Tunnel and Flight Test Results ........ 13 2.2 Simplified Longitudinal Simulation Analysis 16 2.3 Analysis of the Zero G Pushover Maneuver . 18 2.4 Summary of Prior S t u d i e s ................... 22 3. DEVELOPMENT OF THE DHC-6 TWIN OTTER DATABASE . 23 3.1 NASA Lewis Stability and Control Flight T e s t i n g .......................................23 3.2 Twin Otter Tailplane Airfoil Wind Tunnel T e s t ......................................... 28 3.2.1 Discussion of Wind Tunnel Test R e s u l t s ................................ 3 6 3.3 Creation of Tailplane Aerodynamic Coefficients ................................ 46 3.4 Development of the Complete Aircraft Model D a t a b a s e .................................... 51 4. LINEAR DYNAMICAL SYSTEMS ANALYSIS ................. 62 5 . OSU/AARL FLIGHT PATH SIMULATION PROGRAM, TAILSIM 74 5.1 Program O v e r v i e w ............................74 5.2 Program Structure ............................7 6 5.4 Implementation of Reversible Elevator Control M o d e l .........................................8 3 vii 5.5 Implementation of the Pilot M o d e l ............. 88 6. SIMULATION ANALYSIS .................................. 93 6.1 Comparison with Flight Test Parameter Estimation M a n e u v e r s .......................... 94 6.2 Trim Flight Conditions ........................ 99 6.3 Pushover Maneuvers, Uniced Tailplane .... 103 6.4 Pushover Maneuvers with the Iced Tailplane . 114 6.5 Pushover Maneuvers with the Pilot Model . 132 6.6 Discussion and Definition of an Alternate Pushover Maneuver ............................ 14 9 7 . COMPARISON OF FLIGHT TEST AND SIMULATION RESPONSES .......................................... 156 8. TAILPLANE STALL LIMITED MANEUVER CAPABILITY DIAGRAM ............................................ 163 9. SUMMARY AND DISCUSSION ............................. 170 10. CONCLUSIONS AND RECOMMENDATIONS ...................176 LIST OF REFERENCES ..................................... 182 APPENDIX A. DHC-6 TWIN OTTER FLIGHT TEST COEFFICIENTS AND DERIVATIVES ................................... 185 APPENDIX B. DHC-6 TWIN OTTER AIRCRAFT MODEL DATABASE COEFFICIENTS AND DERIVATIVES ..................... 192 APPENDIX C. DHC-6 TWIN OTTER TAILPLANE DATABASE COEFFICIENTS ...................................... 215 APPENDIX D. AIRFOIL TO TAILPLANE CORRECTION CONSTANTS .......................................... 222 APPENDIX E. DOWNWASH CALCULATION....................... 224 APPENDIX F. EQUATIONS OF MOTION, OUTPUTS, AND RUNGE- KUTTA INTEGRATION ................................. 230 Vlll LIST OF TABLES Table 3.1 NASA LeRC DHC-6 Twin Otter Aircraft Specifications .................................. 27 IX LIST OF FIGURES Figure 1-1 Key Aircraft Parameters at Cruise and ApproachG Figure 3.2 OSU 7X10 Wind T u n n e l ....................... 31 Figure 3.3 Baseline Installation, 0„=-26.6° (Wake Probe in Foreground) ..................................... 32 Figure 3.4 LEWICE Ice Shape Installation (View from Upstream) ............................................33 Figure 3.5 Section 1 (Baseline) and Section 2 Airfoil Sections ............................................34 Figure 3.6 Ice Shape Sections ....................... 3 5 Figure 3.7 Lift Characteristics, V=100 kts, 6,=0.0 41 Figure 3.8

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