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Development of a Helicopter Vortex Ring State Warning System Through a Moving Map Display Computer

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Calhoun: The NPS Institutional Archive Theses and Dissertations Thesis Collection 1999-09 Development of a helicopter vortex ring state warning system through a moving map display computer Varnes, David J. Monterey, California. Naval Postgraduate School http://hdl.handle.net/10945/26475 DUDLEY KNOX LIBRARY NAVAL POSTGRADUATE SCHOOL MONTEREY CA 93943-5101 NAVAL POSTGRADUATE SCHOOL Monterey, California THESIS DEVELOPMENT OF A HELICOPTER VORTEX RING STATE WARNING SYSTEM THROUGH A MOVING MAP DISPLAY COMPUTER by David J. Varnes September 1999 Thesis Advisor: Russell W. Duren Approved for public release; distribution is unlimited. Public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instruction, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden, to Washington headquarters Services, Directorate for Information Operations and Reports, 1215 Jefferson Davis Highway, Suite 1204, Arlington. VA 22202-4302, and to the Office of Management and Budget. Paperwork Reduction Project (0704-0188) Washington DC 20503. REPORT DOCUMENTATION PAGE Form Approved OMB No. 0704-0188 2. REPORT DATE 3. REPORT TYPE AND DATES COVERED 1. agency use only (Leave blank) September 1999 Master's Thesis 4. TITLE AND SUBTITLE 5. FUNDING NUMBERS DEVELOPMENT OF A HELICOPTER VORTEX RING STATE WARNING SYSTEM THROUGH A MOVING MAP DISPLAY COMPUTER 6. AUTHOR(S) Varnes, David, J. 7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) PERFORMING ORGANIZATION Naval Postgraduate School REPORT NUMBER Monterey, CA 93943-5000 10. SPONSORING/MONITORING AGENCY 9. SPONSORING / MONITORING AGENCY NAME(S) AND ADDRESS(ES) REPORT NUMBER Office of Naval Research (Naval Science Advisory Program) Mr. CNAL-1.2-99-TSP Steve Kern, Science and Technology Advisor, Commander, Naval Air Force, U.S. Atlantic Fleet, 1279 Franklin St., Norfolk, VA 23511- 2494 11. SUPPLEMENTARY NOTES The views expressed in this thesis are those of the author and do not reflect the official policy or position of the Department of Defense or the U.S. Government. 12a. DISTRIBUTION / AVAILABILITY STATEMENT 12b. DISTRIBUTION CODE Approved for public release; distribution is unlimited. ABSTRACT The need for improved pilot aids has become a high priority item for pilots and aircrews operating at sea and ashore. Pilot aids such as the moving map display, GPWS, collision, and vortex-ring state (VRS) warning systems will significantly enhance aircrew situational awareness and safety. Many more of today's aircraft mishaps are a result of pilot error, which includes a loss of situational awareness. The moving map display provides relatively easy incorporation of sophisticated pilot aids without operational flight program (OFP) modification. This thesis discusses, examines and selects a vortex-ring state prediction algorithm to be incorporated in the GADGHT unit. A program was written that manipulated required aircraft performance data from the ARINC 429 data bus and compared this data to vortex-ring state boundaries predicted by the algorithm. The GADGHT unit provides an audible and visual warning to the pilots when the aircraft has penetrated the VRS boundaries. This warning system will provide increased safety and situational awareness to helicopter crews operating in increasingly demanding operational environments. 14. SUBJECT TERMS 15. NUMBER OF PAGES Vortex Ring State, Power Settling, Settling With Power, Pilot Aids, GADGHT, 153 Ground Air Display for Geographical/Hydrographical Tracking 16. PRICE CODE 17. SECURITY 1. SECURITY 19. SECURITY 20. LIMITATION OF CLASSIFICATION OF ABSTRACT REPORT CLASSIFICATION OF CLASSIFICATION OF THIS PAGE ABSTRACT Unclassified Unclassified Unclassified UL NSN 7540-01-280-5500 Standard Form 298 (Rev. 2-89) Prescribed by ANSI Std 239-18 11 HUDLEY KNOX LIBRARY ^^POSTGRADUATE SCHOOL 943~5101 Approved for public release; distribution is unlimited. DEVELOPMENT OF A HELICOPTER VORTEX RING STATE WARNING SYSTEM THROUGH A MOVING MAP DISPLAY COMPUTER David J. Varnes Lieutenant Commander, United States Navy B.S., Purdue University, 1989 Submitted in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE IN AERONAUTICAL ENGINEERING from the NAVAL POSTGRADUATE SCHOOL September 1999 Y ; A DUDLEY KNOX LIBRAE NAVAL POSTGRADUATE SO* MONTEREY CA tfi ABSTRACT The need for improved pilot aids has become a high priority item for pilots and aircrews operating at sea and ashore. Pilot aids such as the moving map display, GPWS, collision, and vortex-ring state (VRS) warning systems will significantly enhance aircrew situational awareness and safety. Many more of today's aircraft mishaps are a result of pilot error, which includes a loss of situational awareness. The moving map display provides relatively easy incorporation of sophisticated pilot aids without operational flight program (OFP) modification. This thesis discusses, examines and selects a vortex-ring state prediction algorithm to be incorporated in the GADGHT unit. A program was written that manipulated required aircraft performance data from the ARINC 429 data bus and compared this data to vortex-ring state boundaries predicted by the algorithm. The GADGHT unit provides an audible and visual warning to the pilots when the aircraft has penetrated the VRS boundaries. This warning system will provide increased safety and situational awareness to helicopter crews operating in increasingly demanding operational environments. VI TABLE OF CONTENTS I. INTRODUCTION 1 A. PURPOSE 1 B. TERMINOLOGY 1 C. RESEARCH CONTRIBUTION 3 D. ORGANIZATION OF THESIS 4 H. THE GADGHT SYSTEM AND PILOT AIDS 5 A. GADGHT SYSTEM 5 1. Atlas Unit 6 2. Mercury Unit 7 3. Gemini Unit 7 '. 4. Apollo Unit 8 B. FALCONVIEW AND OTHER FLIGHT PLANNING SOFTWARE 10 HI. VORTEX-RING STATE THEORY 13 A. EARLY STUDIES 13 1. Helicopter Behavior in the Vortex-Ring Conditions 13 a. Propeller-Working State 13 b. Vortex-Ring State 14 c. The Windmill-Brake State 14 2. Observations 14 a. Sikorsky R-4B 15 b. Sikorsky R-6 16 c. Sikorsky S-51 16 d. Bell 47 16 e. Bristol 171 17 3. Stewart's Conclusions and Discussion 17 B. SAFETY DATA 18 C. SAFETY IMPLICATIONS 22 vn 1 D. MOMENTUM THEORY AND THE VORTEX-RING STATE 26 1. Momentum Theory In A Hover. 30 2. Momentum Theory In Climbing And Descending Flight 3 3. The Vortex-Ring State..... 32 a. Vortex-Ring State Characteristics 33 4. Autorotation And The Turbulent Wake State 38 5. Windmill Brake State 39 IV. VORTEX-RING STATE BOUNDARY PREDICTION ALGORITHMS 41 A. ALGORITHMS REVIEWED 41 1. Wolkovitch 41 a. Upper Boundary 42 b. Experimental Comparison 45 c. Inclined Descents 46 d. Vortex-Ring State Lower Boundary 46 e. Predicted Vortex-Ring State Boundary 48 2. Peters And Chen 48 a. Background 49 b. Upper And Lower Boundary 52 c. Concluding Remarks 57 3. Gao And Xin 58 a. Experimental Set Up 58 b. Testing And Reduction Of Data 61 c. Results 63 B. EXPERIMENTAL COMPARISONS WITH H-34 DATA 70 C. ALGORITHM CRITIQUE AND SELECTION 76 1. Wolkovitch 77 2. Peters And Chen 79 3. Gao and Xin 80 D. OTHER VORTEX-RING STATE INDICATORS 82 1. Yeates' Vibration Study........ 82 viii 1 a. Results 85 2. H-34 Flight Test Data 88 3. Conclusion 96 V. IMPLEMENTATION 99 A. ALGORITHM DEVELOPMENT 99 1. MATLAB Coding 99 B. IMPLEMENTATION ON THE GADGHT UNIT 101 C. IMPLEMENTATION CONSIDERATIONS 107 1. Ease of Integration into Helicopter Avionics System 107 2. Low Airspeed Sensing 107 3. False Alarm Rates and Missed Warning Concerns 109 4. Validation and Flight Testing 109 VI. CONCLUSIONS AND RECOMMENDATIONS FOR FURTHER STUDY 1 1 APPENDIX A. WARNING SYSTEM PROGRAMMING CODE 115 A. MATLAB PROGRAMMING CODE 115 B. C++ PROGRAMMING CODE 116 APPENDIX B. SOFTWARE SCREEN CAPTURES 123 A. AIRCRAFT AVIONICS SYSTEM 123 B. VORTEX-RING STATE MONITOR START UP WINDOW 124 C. VORTEX-RING STATE MONITOR WARNING 125 D. VORTEX-RING STATE MONITOR WARNING BACKGROUND FLASHING 126 E. SIMULATION SETUP 127 F. PC-104 127 G. KNEEBOARD 128 LIST OF REFERENCES 129 INITIAL DISTRIBUTION LIST 133 ix LIST OF FIGURES Figure 1. GADGHT Atlas Unit From Ref. [5] 6 Figure 2. GADGHT Thor Unit From Ref. [5] 6 Figure 3. GADGHT Mercury Unit from Ref. [5] 7 Figure 4. GADGHT Gemini Unit From Ref. [5] 8 Figure 5. GADGHT Apollo Unit From Ref. [5] 8 Figure 6. Stewart's Airflow Conditions For A Typical Helicopter From Ref. [8] 15 Figure 1 . Typical Flight Envelope From Ref. [1 1] 25 Figure 8. Vortex-Ring State boundary Overlaid On A Climb Performance Chart After Ref. [12] 26 Figure 9. Helicopter Flow States From Ref. [13] 27 Figure 10. Flow Field Condition At The Rotor From Ref. [13] 28 Figure 11. Thrust Variation In Vortex-Ring State From Ref. [13] 34 Figure 12. Power Settling Region Of Vortex-Ring State From Ref. [13] 35 Figure 13. Vortex-Ring State Airbody Formation From Ref. [13] 37 Figure 14. Rotor Row - Ideal Autorotation And Turbulent Wake State From Ref. [14] 39 Figure 15. Wolkovitch's Flow Model From Ref. [15] 42 Figure 16. Induced Velocity Versus Rate Of Descent From Ref. [15] 43 xi Figure 17. Upper Boundary Of Vortex-Ring State From Ref. [15] 44 Figure 18. Drag And Airspeed Relationship From Ref. [1] 45 Figure 19. Measured Thrust Fluctuations - Vertical Descent From Ref. [15] 46 Figure 20. Flow Model For The Lower Vortex-Ring State Boundary From Ref. [15] 47 Figure 21. Predicted Vortex-Ring State Boundary From Ref. [15] 48 Figure 22. Velocity Components, Actual And Normalized From Ref. [16] 50 Figure 23. Induced Flow Versus Rate Of Descent For Various \x Values From Ref [16] 51 Figure 24. Region In Which Momentum Equation Has Three Roots From Ref. [16] 52 Figure 25. Wake Propogation Flow Model From Ref. [16] 53 Figure 26. Vortex-Ring State Boundary From Ref.
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