Introduction to Aerospace Engineering with a Flight Test Perspective
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About the Author xv
Series Preface xvii
Preface xix
About the Companion website xxi
1 First Flights 1
1.1 Introduction 2
1.1.1 Organization of the Book 3
1.1.2 FTT: Your Familiarization Flight 4
1.2 Aircraft 12
1.2.1 Classification of Aircraft 12
1.2.2 The Airplane 13
1.2.3 Rotorcraft: the Helicopter 26
1.2.4 Lighter-Than-Air Aircraft: Balloon and Airship 35
1.2.5 The Unmanned Aerial Vehicle 43
1.3 Spacecraft 45
1.3.1 Classification of Spacecraft 46
1.3.2 Parts of a Spacecraft 52
1.3.3 Unmanned Spacecraft 57
1.3.4 Manned Spacecraft 69
1.3.5 Space Access Systems and Vehicles 77
References 96
2 Introductory Concepts 98
2.1 Introduction 98
2.2 Introductory Mathematical Concepts 99
2.2.1 Units and Unit Systems 99
2.2.2 Measurement and Numerical Uncertainty 107
2.2.3 Scalars and Vectors 113
2.3 Introductory Aerospace Engineering Concepts 114
2.3.1 Aircraft Body Axes 115
2.3.2 Angle-of-Attack and Angle-of-Sideslip 116
2.3.3 Aircraft Stability Axes 118
2.3.4 Aircraft Location Numbering System 119
2.3.5 The Free-Body Diagram and the Four Forces 120
2.3.6 FTT: the Trim Shot 125
2.3.7 Mach Number and the Regimes of Flight 129
2.3.8 The Flight Envelope 132
2.3.9 The V-n Diagram 144
2.3.10 Aircraft Weight and Balance 150
2.3.11 Aerospace Vehicle Designations and Naming 157
2.4 Introductory Flight Test Concepts 161
2.4.1 What is a Flight Test? 161
2.4.2 The Flight Test Process 165
2.4.3 Flight Test Techniques 169
2.4.4 Roles of Test Pilot, Flight Test Engineer, and Flight Test Analyst 173
2.4.5 Flight Test Safety and Risk Assessment 174
References 177
Problems 178
3 Aerodynamics 181
3.1 Introduction 182
3.2 Fundamental Physical Properties of a Fluid 183
3.2.1 The Fluid Element 183
3.2.2 Thermodynamic Properties of a Fluid 184
3.2.3 Kinematic Properties of a Flow 186
3.2.4 Streamlines, Pathlines, and Flow Visualization 187
3.2.5 FTT: In-Flight Flow Visualization 188
3.2.6 Transport Properties of a Fluid 192
3.3 Types of Aerodynamic Flows 195
3.3.1 Continuum and Non-Continuum Flows 195
3.3.2 Steady and Unsteady Flows 196
3.3.3 Incompressible and Compressible Flows 197
3.3.4 Inviscid and Viscous Flows 198
3.4 Similarity Parameters 201
3.4.1 Mach Number 202
3.4.2 Reynolds Number 203
3.4.3 Pressure Coefficient 205
3.4.4 Force and Moment Coefficients 205
3.4.5 Ratio of Specific Heats 206
3.4.6 Prandtl Number 206
3.4.7 Other Similarity Parameters 206
3.4.8 Summary of Similarity Parameters 212
3.5 A Brief Review of Thermodynamics 213
3.5.1 Thermodynamic System and State 213
3.5.2 Connecting the Thermodynamic State: The Equation of State 215
3.5.3 Additional Thermodynamic Properties: Internal Energy, Enthalpy, and Entropy 223
3.5.4 Work and Heat 224
3.5.5 The Laws of Thermodynamics 229
3.5.6 Specific Heats of an Ideal Gas 232
3.5.7 Isentropic Flow 236
3.6 Fundamental Equations of Fluid Motion 239
3.6.1 Conservation of Mass: The Continuity Equation 239
3.6.2 Newton's Second Law: The Momentum Equation 241
3.6.3 Conservation of Energy: The Energy Equation 246
3.6.4 Summary of the Governing Equations of Fluid Flow 247
3.7 Aerodynamic Forces and Moments 248
3.7.1 Lift 251
3.7.2 Drag 258
3.7.3 GTT: Drag Cleanup 269
3.7.4 GTT: Wind Tunnel Testing 270
3.7.5 GTT: Computational Fluid Dynamics 286
3.7.6 FTT: Lift and Drag in Steady, Gliding Flight 292
3.8 Two-Dimensional Lifting Shapes: Airfoils 298
3.8.1 Airfoil Construction and Nomenclature 303
3.8.2 Airfoil Numbering Systems 305
3.8.3 Airfoil Lift, Drag, and Pitching Moment 307
3.8.4 Pressure Coefficient 308
3.8.5 Airfoil Lift, Drag, and Moment Curves 310
3.8.6 Data for Selected Symmetric and Cambered Airfoils 315
3.8.7 Comparison of Symmetric and Cambered Airfoils 322
3.9 Three-Dimensional Aerodynamics: Wings 325
3.9.1 Finite Wings 325
3.9.2 Lift and Drag Curves of Finite Wings 338
3.9.3 High-Lift Devices 341
3.9.4 FTT: Aeromodeling 347
3.9.5 Wings in Ground Effect 354
3.10 Compressible, Subsonic and Transonic Flows 359
3.10.1 The Speed of Sound 360
3.10.2 The Critical Mach Number and Drag Divergence 363
3.10.3 Compressibility Corrections 365
3.10.4 The "Sound Barrier" 370
3.10.5 Breaking the Sound Barrier: the Bell X-1 and the Miles M. 52 371
3.11 Supersonic Flow 377
3.11.1 Isentropic Flow Relations 378
3.11.2 Shock and Expansion Waves 381
3.11.3 FTT: Visualizing Shock waves in Flight 387
3.11.4 Sonic Boom 391
3.11.5 Lift and Drag of Supersonic Airfoils 396
3.11.6 Supercritical Airfoils 399
3.11.7 Wings for Supersonic Flight 401
3.11.8 Transonic and Supersonic Area Rule 417
3.11.9 Internal Supersonic Flows 422
3.12 Viscous Flow 429
3.12.1 Skin Friction and Shearing Stress 430
3.12.2 Boundary Layers 431
3.12.3 Skin Friction Drag 440
3.12.4 Aerodynamic Stall and Departure 444
3.12.5 FTT: Stall, Departure, and Spin Flight Testing 458
3.13 Hypersonic Flow 463
3.13.1 Hypersonic Vehicles 464
3.13.2 Effects of High Mach Number 467
3.13.3 Effects of High Temperature 470
3.13.4 Viscous Hypersonic Flow 473
3.13.5 Effects of Low Density 476
3.13.6 Approximate Analyses of Inviscid Hypersonic Flow 476
3.13.7 Aerodynamic Heating 481
3.13.8 FTT: Hypersonic Flight Testing 485
3.14 Summary of Lift and Drag Theories 495
References 497
Problems 500
4 Propulsion 504
4.1 Introduction 504
4.1.1 The Concept of Propulsive Thrust 505
4.1.2 Engine Station Numbering 509
4.2 Propulsive Flows with Heat Addition and Work 511
4.3 Derivation of the Thrust Equations 513
4.3.1 Force Accounting 514
4.3.2 Uninstalled Thrust for the Rocket Engine 515
4.3.3 Uninstalled Thrust for the Ramjet and Turbojet 518
4.3.4 Installed Thrust for an Air-Breathing Engine 520
4.3.5 Thrust Equation for a Propeller 521
4.4 Thrust and Power Curves for Propeller-Driven and Jet Engines 525
4.4.1 FTT: In-Flight Thrust Measurement 526
4.5 Air-Breathing Propulsion 531
4.5.1 Air-Breathing Propulsion Performance Parameters 532
4.5.2 The Ramjet 538
4.5.3 The Gas Generator 542
4.5.4 The Turbojet Engine 548
4.5.5 The Turbofan Engine 555
4.5.6 The Turboprop and Turboshaft Engines 558
4.5.7 More about Inlets and Nozzles for Air-Breathing Engines 560
4.5.8 The Reciprocating, Piston Engine-Propeller Combination 570
4.5.9 Summary of Thermodynamic Cycles for Air-Breathing Engines 585
4.5.10 GTT: the Engine Test Cell and Test Stand 585
4.5.11 FTT: Flying Engine Testbeds 588
4.6 Rocket Propulsion 589
4.6.1 Thrust Chamber Thermodynamics 590
4.6.2 Rocket Propulsion Performance Parameters 592
4.6.3 Liquid-Propellant Rocket Propulsion 601
4.6.4 Solid-Propellant Rocket Propulsion 604
4.6.5 Hybrid-Propellant Rocket Propulsion 607
4.6.6 Types of Rocket Nozzles 611
4.7 Other Types of Non-Air-Breathing Propulsion 613
4.7.1 Nuclear Rocket Propulsion 614
4.7.2 Electric Spacecraft Propulsion 616
4.7.3 Solar Propulsion 623
4.8 Other Types of Air-Breathing Propulsion 627
4.8.1 The Scramjet 627
4.8.2 Combined Cycle Propulsion 629
4.8.3 Unsteady Wave Propulsion 630
References 634
Problems 635
5 Performance 637
5.1 Introduction 638
5.2 Altitude Definitions 641
5.3 Physical Description of the Atmosphere 644
5.3.1 Chemical Composition of the Atmosphere 645
5.3.2 Layers of the Atmosphere 646
5.3.3 GTT: Cabin Pressurization Test 649
5.4 Equation of Fluid Statics: The Hydrostatic Equation 651
5.5 The Standard Atmosphere 655
5.5.1 Development of the Standard Atmosphere Model 656
5.5.2 Temperature, Pressure, and Density Ratios 661
5.6 Air Data System Measurements 663
5.6.1 The Pitot-Static System 664
5.6.2 Measurement of Altitude 665
5.6.3 Measurement of Airspeed 667
5.6.4 Types of Airspeed 672
5.6.5 Pitot-Static System Errors 678
5.6.6 Other Air Data Measurements 681
5.6.7 FTT: Altitude and Airspeed Calibration 684
5.7 The Equations of Motion for Unaccelerated Flight 690
5.8 Level Flight Performance 692
5.8.1 Thrust Required in Level, Unaccelerated Flight 693
5.8.2 Velocity and Lift Coefficient for Minimum Thrust Required 697
5.8.3 Thrust Available and Maximum Velocity 698
5.8.4 Power Required and Power Available 701
5.8.5 Velocity and Lift Coefficient for Minimum Power Required 705
5.8.6 Range and Endurance 707
5.8.7 FTT: Cruise Performance 712
5.9 Climb Performance 722
5.9.1 Maximum Angle and Maximum Rate of Climb 722
5.9.2 Time to Climb 725
5.9.3 FTT: Climb Performance 727
5.10 Glide Performance 731
5.11 The Polar Diagram 733
5.12 Energy Concepts 735
5.12.1 FTT: Specific Excess Power 745
5.13 Turn Performance 748
5.13.1 The Level Turn 748
5.13.2 Turns in the Vertical Plane 758
5.13.3 Turn Performance and the V-n Diagram 762
5.13.4 FTT: Turn Performance 763
5.14 Takeoff and Landing Performance 766
5.14.1 Takeoff Distance 771
5.14.2 Landing Distance 772
5.14.3 Solution 773
5.14.4 FTT: Takeoff Performance 774
References 778
Problems 779
6 Stability and Control 782
6.1 Introduction 783
6.2 Aircraft Stability 784
6.2.1 Static Stability 785
6.2.2 Dynamic Stability 785
6.3 Aircraft Control 787
6.3.1 Flight Controls 787
6.3.2 Stick-Fixed and Stick-Free Stability 788
6.4 Aircraft Body Axes, Sign Conventions, and Nomenclature 789
6.5 Longitudinal Static Stability 793
6.5.1 The Pitching Moment Curve 793
6.5.2 Configurations with Longitudinal Static Stability and Balance 797
6.5.3 Contributions of Aircraft Components to the Pitching Moment 801
6.5.4 Neutral Point and Static Margin 814
6.6 Longitudinal Control 817
6.6.1 Elevator Effectiveness and Control Power 818
6.6.2 Calculation of New Trim Conditions Due to Elevator Deflection 823
6.6.3 Elevator Hinge Moment 825
6.6.4 Stick-Free Longitudinal Static Stability 827
6.6.5 Longitudinal Control Forces 828
6.6.6 FTT: Longitudinal Static Stability 831
6.7 Lateral-Directional Static Stability and Control 837
6.7.1 Directional Static Stability 838
6.7.2 Directional Control 843
6.7.3 Lateral Static Stability 845
6.7.4 Roll Control 849
6.7.5 FTT: Lateral-Directional Static Stability 851
6.8 Summary of Static Stability and Control Derivatives 856
6.9 Dynamic Stability 857
6.9.1 Long Period or Phugoid 858
6.9.2 Short Period 861
6.9.3 Dutch Roll 862
6.9.4 Spiral Mode 864
6.9.5 Roll Mode 865
6.9.6 FTT: Longitudinal Dynamic Stability 866
6.10 Handling Qualities 872
6.10.1 FTT: Variable-Stability Aircraft 873
6.11 FTT: First Flight 876
References 880
Problems 880
Appendix A Constants 882
A.1 Miscellaneous Constants 882
A.2 Properties of Air at Standard Sea Level Conditions 882
Appendix B Conversions 883
B.1 Unit Conversions 883
B.2 Temperature Unit Conversions 884
Appendix C Properties of the 1976 US Standard Atmosphere 885
C.1 English Units 885
C.2 SI Units 887
Index 891
Chapter 1
First Flights
The first controlled flight of a heavier-than-air airplane, 17 December 1903.
(Source: W. Wright, O. Wright, and J. Daniels, 1903, US Library of Congress.)
"Wilbur, having used his turn in the unsuccessful attempt on the 14th, the right to the first trial now belonged to me. After running the motor a few minutes to heat it up, I released the wire that held the machine to the track, and the machine started forward in the wind. Wilbur ran at the side of the machine, holding the wing to balance it on the track. Unlike the start on the 14th, made in a calm, the machine, facing a 27-mile wind, started very slowly. Wilbur was able to stay with it till it lifted from the track after a forty-foot run. One of the Life Saving men snapped the camera for us, taking a picture just as the machine had reached the end of the track and had risen to a height of about two feet.1 The slow forward speed of the machine over the ground is clearly shown in the picture by Wilbur's attitude. He stayed along beside the machine without any effort.
The course of the flight up and down was exceedingly erratic, partly due to the irregularity of the air, and partly to lack of experience in handling this machine. The control of the front rudder was difficult on account of its being balanced too near the center. This gave it a tendency to turn itself when started; so that it turned too far on one side and then too far on the other. As a result the machine would rise suddenly to about ten feet, and then as suddenly dart for the ground. A sudden dart when a little over a hundred feet from the end of the track, or a little over 120 ft from the point at which it rose into the air, ended the flight. As the velocity of the wind was over 35 ft per second and the speed of the machine over the ground against this wind ten feet per second, the speed of the machine relative to the air was over 45 ft per second, and the length of the flight was equivalent to a flight of 540 feet made in calm air. This flight lasted only 12 seconds, but it was nevertheless the first in the history of the world in which a machine carrying a man had raised itself by its own power into the air in full flight, had sailed forward without reduction of speed and had finally landed at a point as high as that from which it started."
Orville Wright writing about the first successful flight of a heavier-than-air flying machine from Kill Devil Hills, North Carolina, on 17 December, 19032
1.1 Introduction
The history of aerospace engineering is full of firsts, such as the first balloon flight, the first airplane flight, the first helicopter flight, the2 first artificial satellite flight, the first manned spacecraft flight, and many others. In this first chapter, these many firsts are discussed in the context of the aerospace engineering involved in making these historic events happen. The first flight of a new vehicle design is a significant achievement and milestone. It is usually the culmination of years of hard work by many people, including engineers, technicians, managers, pilots, and other support personnel. First flights often represent firsts in the application of new aerospace engineering concepts or theories that are being validated by the actual flight.
As an aerospace engineer, you have the opportunity to contribute to the first flight of a new aircraft, a new spacecraft, or a new technology. Aerospace engineers are involved in all facets of the design, analysis, research, development, and testing of aerospace vehicles. This encompasses many different aerospace engineering discipline specialties, including aerodynamics, propulsion, performance, stability, control, structures, systems, and others. Several of these fundamental disciplines of aerospace engineering are introduced in this text. The aerospace engineer tests the vehicle, on the ground and in flight, to verify that it can perform as predicted and to improve its operating characteristics. Flight testing is usually the final test to be performed on the complete vehicle or system.
In many areas of engineering and technology, there is sometimes a perception that there is "nothing left to be done", or that "there is nothing left to be invented". The impressive successes of our aerospace past may appear, to some, to dim the prospects for future innovations. Aerospace engineers have indeed designed, built, and flown some of the most innovative, complex, and amazing machines known to humanity. However, there is still ample room for creativity and innovation in the design of aerospace vehicles, and opportunities for technological breakthroughs to make the skies and stars far more accessible. By the end of this textbook, you will have greatly increased your knowledge of aerospace engineering, but you will also be humbled by how much more there is to be discovered.
1.1.1 Organization of the Book
Aerospace engineering encompasses the fields of aeronautical and astronautical engineering. As a broad generalization, the aeronautical field tends to deal with vehicles that fly through the sensible atmosphere, that is, aircraft. Astronautics deals with vehicles that operate in the airless space environment, that is, spacecraft. Aerospace engineering is, in many ways, a merging of these two fields, and includes aircraft, spacecraft, and other vehicles that operate in both the air and space environments. In the coming sections, we get more precise with the definitions of the various types of aerospace vehicles, such as aircraft and spacecraft.
The material in the text is organized in an academic building-block fashion as shown in Figure 1.1. In Chapter 1, we start by defining and discussing some of the many different types of aircraft and spacecraft. Many first flights of these different types of aerospace vehicles are described, providing insights and perspectives into the development and evolution of aerospace engineering. The terms aircraft and spacecraft are clearly defined, along with definitions of the various parts, components, and assemblies that make up various examples of these types of vehicles. The reader also makes a literary "first flight" in a modern, supersonic jet airplane, which introduces many of the areas to be discussed in the coming chapters.
Figure 1.1 Academic building blocks followed in the text.
In Chapter 2, several introductory concepts in aerospace engineering and flight test are discussed. This chapter gives the reader some of the basic concepts and terminology, in aerospace engineering and flight test, from which to learn the material in the subsequent chapters. Some basic mathematical ideas, definitions, and concepts are reviewed, which starts to fill our engineering toolbox with the basic tools required to analyze and design aerospace vehicles. Basic aerospace engineering concepts, relating to the flight of aerospace vehicles, are introduced, including aircraft axis systems, free-body diagrams, the regimes of flight, and the flight envelope. Basic flight test concepts are introduced, including the different types of flight test, the flight test process, the players involved, and the use of flight test techniques.
The fundamental disciplines of aerodynamics and propulsion are discussed in Chapters 3 and 4, respectively. The study of aerodynamics, in Chapter 3, provides the theories and tools required to analyze the flow of air over aerospace vehicles, the flow that produces aerodynamic forces such as lift and drag. We discover how and why these aerodynamic forces are created, and how this affects the design of aerodynamic surfaces such as airfoils and wings. In studying propulsion in Chapter 4, we learn about the devices that generate the thrust force to propel aerospace vehicles both in the atmosphere and in space. We develop a deeper understanding of how thrust is produced, regardless of the type of machinery that is used.
The study of performance, in Chapter 5, builds upon an understanding of aerodynamics and propulsion, as shown graphically in Figure 1.1. Performance deals with the linear motion of the vehicle caused by the aerodynamic forces (lift and drag) and propulsive force (thrust) acting upon it. Performance seeks to determine how fast, how high, how far, and how long a vehicle can fly.
In Chapter 6, the study of stability and control also builds upon the fundamental disciplines of aerodynamics and propulsion. Stability and control deals with the angular motion of the vehicle caused by the aerodynamic and propulsive moments acting on it. We investigate the vehicle's stability when disturbed from its equilibrium condition and seek to understand the impacts of various vehicle configurations and geometries. We also look at the means by which the vehicle can be controlled throughout its flight regime.
Many examples of ground and flight testing are integrated throughout the text, in sections entitled Ground Test Techniques and Flight Test Techniques. The flight test techniques are described in a unique manner, by placing the reader "in the cockpit" of different aircraft as the test pilot or flight test engineer. The reader obtains an intimate knowledge of the engineering concepts, test techniques, and in-flight data collection by "flying" the flight test techniques. A collateral benefit of this approach is that the reader is familiarized with several different types of real aircraft.
1.1.2 FTT: Your Familiarization Flight
This is the...
