Air Force Institute of Technology AFIT Scholar Theses and Dissertations Student Graduate Works 3-2007 Experimental Investigation of Oblique Wing Aerodynamics at Low Speed Matthew J. Dillsaver Follow this and additional works at: https://scholar.afit.edu/etd Part of the Aerodynamics and Fluid Mechanics Commons Recommended Citation Dillsaver, Matthew J., "Experimental Investigation of Oblique Wing Aerodynamics at Low Speed" (2007). Theses and Dissertations. 2963. https://scholar.afit.edu/etd/2963 This Thesis is brought to you for free and open access by the Student Graduate Works at AFIT Scholar. It has been accepted for inclusion in Theses and Dissertations by an authorized administrator of AFIT Scholar. For more information, please contact [email protected]. EXPERIMENTAL INVESTIGATION OF OBLIQUE WING AERODYNAMICS AT LOW SPEED THESIS Matthew J. Dillsaver, Captain, USAF AFIT/GAE/ENY/07-M10 DEPARTMENT OF THE AIR FORCE AIR UNIVERSITY AIR FORCE INSTITUTE OF TECHNOLOGY Wright-Patterson Air Force Base, Ohio APPROVED FOR PUBLIC RELEASE; DISTRIBUTION UNLIMITED The views expressed in this thesis are those of the author and do not reflect the official policy or position of the United States Air Force, Department of Defense, or the United States Government. AFIT/GAE/ENY/07-M10 EXPERIMENTAL INVESTIGATION OF OBLIQUE WING AERODYNAMICS AT LOW SPEED THESIS Presented to the Faculty Department of Aeronautics and Astronautics Graduate School of Engineering and Management Air Force Institute of Technology Air University Air Education and Training Command In Partial Fulfillment of the Requirements for the Degree of Master of Science in Aeronautical Engineering Matthew J. Dillsaver, BSME Captain, USAF March 2007 APPROVED FOR PUBLIC RELEASE; DISTRIBUTION UNLIMITED. AFIT/GAE/ENY/07-M10 EXPERIMENTAL INVESTIGATION OF OBLIQUE WING AERODYNAMICS AT LOW SPEED Matthew J. Dillsaver, BSME Captain, USAF Approved: ____________________________________ Dr. Milton Franke (Chairman) date ____________________________________ Dr. Paul King (Member) date ____________________________________ Lt. Col. Raymond Maple (Member) date AFIT/GAE/ENY/07-M10 Abstract In an effort to increase the range of missiles and guided bombs, the USAF is looking at options for new wing configurations. One such configuration being considered is oblique wings. An oblique wing is a wing that pivots about a point on the aircraft fuselage thereby having one side swept forward and the other swept aft. Additional interest is looking at a wing only configuration that also rotates with one wing tip forward of the other. Studies have shown that this configuration can provide less drag for a given lift at both supersonic cruise and subsonic loiter conditions. This experiment focused on the low speed performance of a missile model with an oblique wing. The wing was tested at seven different sweep angles and at two different speeds. In order to simulate the missile dropping from an aircraft the model was inverted over a stationary ground plane in the tunnel and tested at the same wing obliquity angles. Stalling was found at certain conditions including sweep angles of 0, 15, and 30 deg. The ground plane was shown to result in an increase in lift as well as an increase in drag. The ground plane was also shown to add more longitudinal stability, thus making the missile better performing when dropped from an aircraft. iv AFIT/GAE/ENY/07-M10 To my fiancé for all of her love and support throughout this project v Acknowledgements I would like to thank everyone who assisted me throughout this study. I would especially like to thank my thesis advisor, Dr. Franke, for his vast knowledge and guidance. I would also like to express my sincere gratitude to Mr. Dwight Gehring, AFIT/ENY, for his invaluable help in set-up, calibration, and operation of the wind tunnel. Lastly, I would like to thank Mr. Jay Anderson for the set-up and operation of the ENY 3-D rapid prototyping machine. Matthew J. Dillsaver vi Table of Contents Page Abstract ......................................................................................................................iv Acknowledgements .................................................................................................... vi Table of Contents ...................................................................................................... vii List of Figures ............................................................................................................. ix List of Tables ........................................................................................................... xiii List of Symbols ........................................................................................................ xiv I. Introduction ............................................................................................................1 Section 1 - Oblique Wings......................................................................................1 Section 2 - Ground Effects......................................................................................3 Section 3 – Research Objectives and Approach .....................................................3 II. Literature Review...................................................................................................5 Section 1 - Oblique Wings.....................................................................................5 Section 2 - Ground Effects.....................................................................................7 III. Experimental Setup..............................................................................................15 Section 1 - Wind Tunnel......................................................................................15 Section 2 - Balance ..............................................................................................17 Section 3 - Missile Model and Wing ...................................................................18 Section 4 - Ground Plane .....................................................................................21 Section 5 - Experimental Procedure ....................................................................24 Section 6 - Data Analysis.....................................................................................29 IV. Results and Analysis.............................................................................................30 Verification of Balance and Data Reduction Program ........................................30 Middle Wing ........................................................................................................34 In-Ground Effects ................................................................................................39 Front Wing...........................................................................................................52 Uncertainty Analysis............................................................................................58 vii Page V. Conclusions and Recommendations ......................................................................60 Section 1 - Conclusions .......................................................................................60 Section 2 - Recommendations .............................................................................61 Appendix A. Data Reduction Sample Calculation .....................................................63 Appendix B. Additional Plots.....................................................................................66 Appendix C. MATLAB Data Reduction Program .....................................................77 References....................................................................................................................85 Vita...............................................................................................................................88 viii List of Figures Figure Page Figure 1. Blohm and Voss P-202 [1]…………………………..............………………2 Figure 2. NASA AD-1 [4]………………………………………............……………..2 Figure 3. Illustration of 2X length for oblique wings [1]……………...............……….5 Figure 4. Comparison of induced drag for oblique and delta wing [9]…................…...6 Figure 5. Airflow around wing OGE and wing IGE [1]…………............……………..8 Figure 6. Graph of Weiselsberger’s induced drag formula [7]…...............…………….9 Figure 7. McCormick’s induced drag factor [14]…………………..............………….10 Figure 8. Conditions needing an endless belt ground plane [22]………......…………..13 Figure 9. Wind tunnel converging section dimensions………………………………...16 Figure 10. AFIT wind tunnel schematic………………………………………………..16 Figure 11. Wind tunnel test section…………………………………………………….17 Figure 12. Missile model mounted in tunnel...................................................................18 Figure 13. Airfoil profile..................................................................................................19 Figure 14. Sweep angle convention used………………………………………………20 Figure 15. SolidWorks drawing of wing.........................................................................21 Figure 16. Ground plane [5].............................................................................................22 Figure 17. Top view of ground plane with pieces separated [5]......................................23 Figure 18. Ground plane leading edge [5].......................................................................24 Figure 19. Tunnel coordinate system [29]........................................................................25