. Douglas A. Joyce Library of Congress Cataloging-in-Publication Data Joyce, Douglas A. Flying beyond the stall : the X-31 and the advent of supermaneuverability / by Douglas A. Joyce. pages cm Includes bibliographical references and index. 1. Stability of airplanes--Research--United States. 2. X-31 (Jet fighter plane) 3. Research aircraft--United States. 4. Stalling (Aerodynamics) I. Title. TL574.S7J69 2014 629.132’360724--dc23 2014022571 During the production of this book, the Dryden facility was renamed the Armstrong Flight Research Center. All references to the Dryden facility have been preserved for historical accuracy. Copyright © 2014 by the National Aeronautics and Space Administration. The opinions expressed in this volume are those of the authors and do not necessarily reflect the official positions of the United States Government or of the National Aeronautics and Space Administration. ISBN 978-1-62683-019-6 90000 9 781626 830196 This publication is available as a free download at http://www.nasa.gov/ebooks. Author Dedication v Foreword: The World’s First International X-Airplane vii Prologue: The Participants xi Chapter 1: Origins and Design Development .......................................................1 In the Beginning…: The Quest for Supermaneuverability ........................3 Defining a Supermaneuverable Airplane: The Path to EFM ......................5 Design and Development of the X-31 ................................................. 13 Fabrication to Eve of First Flight .......................................................... 20 Chapter 2: Into the Air: Initial Flight Testing ...................................................... 33 Preflight Preparations Through Initial Flight Exploration ........................ 34 Assessing the X-31’s Basic Flying Qualities ......................................... 38 Whither X-31? Program Relocation to Dryden ..................................... 43 Program Expansion: Probing the Post-Stall Environment ...................... 48 Chapter 3: Expanding the X-31’s Research Program ....................................... 63 The Pinball Simulations ...................................................................... 64 From Pinball to TUFT .......................................................................... 77 PST Aloft: Proving the X-31 “1-v-1” .................................................... 84 PST in the Dogfight Arena: Concluding Observations ........................... 98 Chapter 4: The X-31 Follow-On Program ........................................................ 105 Of HUDs and Helmets ...................................................................... 105 X-31 Handling Qualities and Close-In Combat ................................... 109 Tracking Tasks in the High-Alpha Arena ........................................... 115 Continuously “Predicting” Aerodynamics ........................................... 118 The X-31 and JAST’s Quest for “Quasi-Tailless” Flight ....................... 118 The X-31 “Goes to Sea” ................................................................... 123 The X-31 as a Quasi-Tailless Ground Attacker ................................... 130 iii Flying Beyond the Stall Chapter 5: Desert Disaster, Triumph in Paris, and a New VECTOR ................. 139 A Matter of Pitot Icing… .................................................................. 140 On to Paris ...................................................................................... 146 The X-31 Flies at Le Bourget ............................................................ 158 VECTOR for the Future ..................................................................... 162 Chapter 6: Program Management and Direction ............................................ 175 The International Partnership ............................................................ 175 Contractor, Government, and ITO Responsibilities .............................. 178 Costs, Cost Analysis, and Program Funding ....................................... 184 Chapter 7: The X-31 in Retrospect .................................................................. 189 In Sum… ........................................................................................ 189 Lessons Learned ............................................................................ 193 Epilogue ........................................................................................................... 217 Appendices: Appendix 1: Disseminating X-31 Research Results and Lessons ........ 221 Appendix 2: X-31 Flight Log ............................................................. 239 Appendix 3: X-31 Dimensions, Weights, and Performance Specifications .................................................................................. 293 Appendix 4: X-31 Chronology ........................................................... 297 Appendix 5: X-31 Pilots and Their Sorties ......................................... 305 Appendix 6: Acronyms and Abbreviations .......................................... 307 Appendix 7: X-31 Lessons Learned: An Expanded View ..................... 317 Acknowledgments 363 Selected Bibliography 366 About the Author 375 Index 377 iv Author Dedication To Phyllis Joyce The wind under my wings in life And the thrust vector for this book. v X-31 Initial test pilots at Plant 42: (left to right) Fred Knox, Dietrich Seeck, Ken Dyson, and Karl Lang. (Rockwell) vi FOREWORD The World’s First International X-Airplane On Wednesday, October 11, 1990, a small blue-and-white jet took to the air from Air Force Plant 42 at Palmdale, CA. For the next 38 minutes, it cruised at 10,000 feet over California’s Antelope Valley, reaching a top speed of 340 miles per hour (mph) before Rockwell International test pilot Norman K. “Ken” Dyson returned it gently to Earth. By the standards of the Antelope Valley—known to locals as “Aerospace Valley” (AV)—it was a seemingly innocuous flight. Over the four previous decades, AV had witnessed the birth of supersonic flight. Palmdale, one of its two major communities, was the roost of the Mach 3+ SR-71 Blackbird and its subsonic stablemate, the U-2. Edwards, less than 25 miles away, was home to both the Air Force Flight Test Center and the National Aeronautics and Space Administration (NASA) Ames-Dryden Flight Research Facility (now the NASA Armstrong Flight Research Center), where exotic high-performance military and research aircraft routinely flew over its vast, baked dry lakes—Rosamond and Rogers. In 1977, the Space Shuttle was first flown freely through its skies, and in 1981, the Shuttle Columbia returned from orbit to land at Edwards, heralding the era of the reusable, refurbishable spacecraft. To those unfamiliar with aircraft, at first glance, the little airplane looked like any other fighter overflying the Mojave Desert. But appearances were deceiving, for this was the X-31, then the latest of the U.S. X-planes, the leg- endary research tools of the supersonic era that had pushed back the frontiers of flight beginning with the Bell XS-1. Each of the X-planes had their own uniqueness and X-31 was no different in that regard—in fact, it was unique in many ways. Perhaps the most distinguishing characteristic of the X-31 program was that it was the only multinational program of the X series of research vehi- cles. It was the product of German-American interest. The X-31 was intended to fulfill four goals: demonstrate controlled flight and high agility beyond the stall, using thrust vectoring that was integrated with electronic flight controls; investigate the benefits of enhanced maneuverability for future military aircraft via close-in air combat maneuvering tests; develop design requirements and vii Flying Beyond the Stall a database for future aircraft applications; and validate low-cost international prototyping. To fulfill those purposes, Rockwell and German manufacturer Messerschmitt-Bölkow-Blohm (MBB) designed, developed, and built two of the shapely X-31 aircraft using a variety of new and off-the-shelf components blended with creative and insightful engineering and design. Over the next 14 years, through its final Vectoring ESTOL (extreme short takeoff and landings) Control Tailless Operation Research (VECTOR) flight (on April 29, 2004), the X-31 accomplished all this and more. As the program drew to a close, it received several major awards, notably the American Institute of Aeronautics and Astronautics (AIAA) Aircraft Design Award (September 1994). In July 1995, with the program then thought to be concluded, the Smithsonian Institution presented the X-31 International Test Organization with the prestigious National Air and Space Museum Trophy for Current Achievement, an honor established to recognize extraordinary service in air and space science and technology. In making the award, Smithsonian Provost Robert S. Hoffmann stated the following: The X-31 International Test Organization is being awarded the 1995 Trophy for Current Achievement for an unprecedented record of engineering and flight exploration accomplishments in the past year. You have culminated a highly successful experi- mental program with a series of momentous “firsts” in aviation history, demonstrating the significant value of post-stall agility in close-in air combat, developing and demonstrating revolutionary helmet-mounted visual and aural pilot aids for situational aware- ness under WVR [within visual range] combat conditions, and conducting an epoch-making series of flights in which the X-31 employed