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MODELING FLIGHT The Role of Dynamically Scaled Free-Flight Models in Support of NASA’s Aerospace Programs Joseph Chambers MODELING � FLIGHT The Role of Dynamically Scaled Free-Flight Models in Support of NASA’s Aerospace Programs Joseph R. Chambers Library of Congress Cataloging-in-Publication Data Chambers, Joseph R. Modeling flight : the role of dynamically scaled free-flight models in support of NASA’s aerospace programs / by Joseph R. Chambers. p. cm. “NASA SP 2009-575.” Includes bibliographical references and index. 1. Airplanes--Models--United States--Testing. 2. Wind tunnel models--United States--Testing. 3. Aeronautics--Research--United States--Methodology. 4. United States. National Aeronautics and Space Administration. I. Title. TL567.M6C48 2010 629.101’1--dc22 2009048942 TABLE OF CONTENTS Acknowledgements....................................................................................................................vii Introduction...................................................................................................................................1 Background...................................................................................................................................7 Objectives................................................................................................................................ 7 Role.of.Free-Flight.Testing.......................................................................................................8 Principles.of.Dynamic.Scaling..................................................................................................9 Rigid-Body.Dynamic.Models..................................................................................................11 Incompressible.Flow...............................................................................................................11 Compressible.Flow.................................................................................................................14 Limitations.and.Interpretation.of.Results................................................................................15 Historical.Development.by.the.NACA.and.NASA....................................................................17 Spin.Research.Facilities.........................................................................................................18 The.Langley.20-Foot.Spin.Tunnel..........................................................................................19 Wind.Tunnel.Free-Flight.Research.Facilities..........................................................................22 The.Langley.12-Foot.Free-Flight.Tunnel................................................................................24. The.Langley.Full-Scale.Tunnel...............................................................................................26. The.Ames.Hypervelocity.Free-Fight.Facilities........................................................................29 The.Ames.40-.by.80-Foot.Tunnel...........................................................................................32 Outdoor.Free-Flight.Facilities.and.Ranges.............................................................................33 Langley.Unpowered.Drop.Models..........................................................................................33 TABLE OF CONTENTS iii Dryden.Unpowered.Drop.Models........................................................................................... 37 Langley.Powered.Free-Flight.Models..................................................................................... 39 Langley.Control.Line.Facility.................................................................................................. 40 Ames.Powered.Free-Flight.Models........................................................................................ 41 Dryden.Powered.Free-Flight.Models...................................................................................... 41 Wallops.Rocket-Boosted.Models............................................................................................ 42 Selected.Applications................................................................................................................ 43. Dynamic.Stability.and.Control.................................................................................................. 47. Low-Speed.Research.............................................................................................................. 47 High-Speed.Research:.Rocket-Propelled.Models................................................................... 50 Supersonic.Tests.at.Ames....................................................................................................... 52 Unconventional.Configurations............................................................................................... 52 The.Early.Days........................................................................................................................ 53 V/STOL.Configurations........................................................................................................... 58 Parawing.Configurations......................................................................................................... 65 Variable.Geometry................................................................................................................... 68 Space.Capsules...................................................................................................................... 73 Reentry.Vehicles.and.Lifting.Bodies........................................................................................ 75 Supersonic.Transports............................................................................................................ 79 Vehicle/Store.Separation......................................................................................................... 80 Advanced.Civil.Aircraft............................................................................................................ 83 Wake.Vortex.Hazard............................................................................................................... 84 iv MODELING FLIGHT Towed.Vehicles.......................................................................................................................85 Concept.Demonstrators..........................................................................................................86 Summary................................................................................................................................88 Flight.at.High.Angles.of.Attack.................................................................................................89 Fighters...................................................................................................................................94 Summary...............................................................................................................................102 Spinning.and.Spin.Recovery...................................................................................................103 Background..........................................................................................................................103 Military.Configurations..........................................................................................................105 General-Aviation.Configurations...........................................................................................116 Skewed.Wing.Configuration.................................................................................................117 Summary...............................................................................................................................117 Spin.Entry.and.Poststall.Motions...........................................................................................119 Spin.Entry.............................................................................................................................119 Military.Configurations..........................................................................................................120 General-Aviation.Configurations...........................................................................................131 Jet.Transport.Upset.Recovery..............................................................................................135 Tumbling...............................................................................................................................136 Other.Studies........................................................................................................................137 Summary...............................................................................................................................138 Associated.Test.Techniques.................................................................................................. 139 Aerodynamic.Data................................................................................................................139 TABLE OF CONTENTS v Static.Tests........................................................................................................................... 140 Forced-Oscillation.Tests....................................................................................................... 141 Free-to-Roll.Tests................................................................................................................. 142 Rotary-Balance.Tests........................................................................................................... 144 Free-to-Pitch.Tests............................................................................................................... 145 Future.Perspectives................................................................................................................ 147 References............................................................................................................................... 151 About.the.Author..................................................................................................................... 169 Index..........................................................................................................................................171 vi MODELING FLIGHT ACKNOWLEDGEMENTS I sincerely thank the dozens of current and retired employees of the National Aeronautics and Space Administration (NASA) and its predecessor, the National Advisory Committee for Aeronautics (NACA) who shared their invaluable corporate memory and personal files in the preparation of this monograph. The challenge of attempting to chronicle and document over 80 years of research and development activities was extremely daunting and would have been impossible were it not for the assistance and encouragement of these individuals. Their direct participation in this project has ensured the preservation and archival documentation of some of the most remarkable test activities ever conducted at the NASA Langley Research Center, the NASA Ames Research Center, the NASA Dryden Flight Research Center, and the NASA Wallops Flight Facility. Special thanks go to the following individuals, who contributed material for this pub- lication: Long P. Yip, Norman L. Crabill, Mark A. Croom, John Sain, Donald B. Owens, Kevin Cunningham, Sue B. Grafton, Dan D. Vicroy, and Joseph L. Johnson, Jr. Special thanks goes to Anthony M. Springer of NASA Headquarters for providing the encouragement and mechanism for this undertaking and to Lynn Bondurant and Dorothy Watkins of Paragon TEC for coordinat- ing the preparation and administration of the effort. Sue B. Grafton and Frederick J. Lallman provided access to many historical documents and photographs at Langley, and Lana L. Albaugh, Edward M. Schilling, and Jack Boyd contributed at Ames. Thanks also to Garland Gouger and the staff of the Langley technical library for assistance in accessing documents. Photo archivist Alicia Bagby also provided access to photographs in the Langley collection. Graphics specialist Gerald Lee Pollard of Langley made available his outstanding talent and materials. Thanks also to Mike Fremaux, Ray Whipple (retired), and Don Riley (retired) of Langley; Chuck Cornelison of Ames; Christian Gelzer of Dryden; Greg Finley of NASA Headquarters for their superb editing efforts and suggestions; and Janine Wise of NASA Headquarters provided professional layout and organization. ACKNOWLEDGEMENTS vii THIS PAGE INTENTIONALLY BLANK INTRODUCTION T he state of the art in aeronautical engineering has been continually accelerated by the development of advanced analysis and design tools. Used in the early design stages for aircraft and spacecraft, these methods have provided a fundamental understanding of physical phenomena and enabled designers to predict and analyze critical characteristics of new vehicles, including the capability to control or modify unsatisfactory behavior. For example, the relatively recent emergence and routine use of extremely power- ful digital computer hardware and software has had a major impact on design capabilities and procedures. Sophisticated new airflow measurement and visualization systems permit the analyst to conduct micro- and macro-studies of properties within flow fields on and off the surfaces of models in advanced wind tunnels. Trade studies of the most efficient geometrical shapes for aircraft can be conducted with blazing speed within a broad scope of integrated technical disciplines, and the use of sophisticated piloted simulators in the vehicle development process permits the most important segment of operations—the human pilot—to make early assessments of the acceptability of the vehicle for its intended mission. Knowledgeable applica- tions of these tools of the trade dramatically reduce risk and redesign, and increase the marketability and safety of new aerospace vehicles. Arguably, one of the more viable and valuable design tools since the advent of flight has been testing of subscale models. As used herein, the term “model” refers to a physical article used in experimental analy- ses of a larger full-scale vehicle. The reader is probably aware that many other forms of mathematical and computer-based models are also used in aerospace design; however, such topics are beyond the intended scope of this document. Model aircraft have always been a source of fascination, inspiration, and recreation for humans since the earliest days of flight. Within the scientific community, Leonardo da Vinci, George Cayley, and the Wright brothers are examples of early aviation pioneers who frequently used models during their scientific efforts to understand and develop flying machines. Progress in the technology associated with model testing in worldwide applications has firmly established model aircraft as a key element in new aerospace research and development programs. Models are now routinely used in many applications and roles, including aerodynamic data gathering in wind tunnel investigations for the analysis of full-scale INTRODUCTION 1

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MODELING . FLIGHT. The Role of Dynamically Scaled. Free-Flight Models in Support of NASA's Aerospace Programs. Joseph R. Chambers denotes full-scale airplane at sea level and model at sea level, (b) full-scale airplane at 30,000 ft and model at sea level, (c) full-scale airplane at sea level
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