Theory and Practice of Aircraft Performance
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Ajoy Kumar Kundu graduated with Mechanical Engineering degree from Jadavpur University, India, followed by studying in the United Kingdom (Cranfield University and Queen's University Belfast) and in the United States of America (University of Michigan and Stanford University). His professional experience spans more than thirty years in the aircraft industries and nearly 20 years in academia. In India, he was Professor at the Indian Institute of Technology, Kharagpur; and the Chief Designer at the Hindustan Aeronautics, Bangalore. In North America, he served as Research Engineer for the Boeing Aircraft Company, Renton and as Intermediate Engineer for Canadair Ltd. His aeronautical engineering career began in the United Kingdom with Short Brothers and Harland Ltd., retiring from Bombardier Aerospace-Belfast, as Assistant Chief Aerodynamicist. He is currently associated with Queen's University Belfast. He has authored the book title Aircraft Design published by Cambridge University Press. He held British, Canadian and Indian Private Pilot's License. He is a Fellow of the Royal Aeronautical Society and the Institute of Mechanical Engineers, UK.
Professor Mark Price is the Pro-Vice-Chancellor for the Faculty of Engineering and Physical Sciences at Queen's University Belfast. Formerly he was the Head of School of Mechanical and Aerospace Engineering having progressed through his academic career as a Professor of Aeronautics teaching aircraft structures and design, and leading a research team in design and manufacturing. He graduated in 1987 with a 1st Class Honours degree in Aeronautical Engineering from Queen's University Belfast before taking up a post as a stress engineer in Bombardier Aerospace. He returned later to QUB to undertake a PhD in Mechanical Engineering after which he joined TranscenData Europe as a software engineer and project manager to implement his research in their product CADFix. In 1998 he returned to QUB lecturing in aircraft structures and design. With a strong focus on design applications and integrated performance and cost models, including manufacturing processing effects in design simulations, he received the 2006 Thomas Hawksley medal from the IMechE. He has published over 200 articles and supervised 20 PhDs to completion. Mark is a Fellow of the Royal Aeronautical Society and the Institute of Mechanical Engineers, UK.
David Riordan commenced employment with Short Brothers PLC in 1978 as an Undergraduate Apprentice. He then graduated in 1982 from Queen's University Belfast, with a 1st Class Honours degree in Mechanical Engineering. In 1986 he attained an MSc in Advanced Manufacturing Technology from the Cranfield Institute of Technology, England. David was appointed Chief Technical Engineer during 2002; in which position provides leadership at the Bombardier Belfast site for all activities associated with the technical engineering fields of aerodynamics, thermodynamics, fire safety and noise; mechanical systems, electrical systems, reliability & safety. David is also functionally responsible for the department of Airworthiness and Engineering Quality. Responsibilities cover all products associated with Bombardier at Belfast, including metallic fuselage barrels (business jet and regional aircraft applications); composite aerostructures (including the composite wing for the Bombardier CSeries aircraft) and engine nacelles (including the complete nacelle system for the PW1400G-JM propulsion system powering the IRKUT MC-21 aircraft).
Content
Preface xix
Series Preface xxi
Road Map of the Book xxiii
Acknowledgements xxvii
Nomenclature xxxi
Introduction 1
1.1 Overview 1
1.2 Brief Historical Background 1
1.2.1 Flight in Mythology 1
1.2.2 Fifteenth to Nineteenth Centuries 1
1.2.3 From 1900 to World War I (1914) 3
1.2.4 World War I (1914-1918) 4
1.2.5 The Inter-War Period: the Golden Age (1918-1939) 7
1.2.6 World War II (1939-1945) 7
1.2.7 Post World War II 8
1.3 Current Aircraft Design Status 8
1.3.1 Current Civil Aircraft Trends 9
1.3.2 Current Military Aircraft Trends 10
1.4 Future Trends 11
1.4.1 Trends in Civil Aircraft 11
1.4.2 Trends in Military Aircraft 13
1.4.3 Forces and Drivers 14
1.5 Airworthiness Requirements 14
1.6 Current Aircraft Performance Analyses Levels 16
1.7 Market Survey 17
1.8 Typical Design Process 19
1.8.1 Four Phases of Aircraft Design 19
1.9 Classroom Learning Process 23
1.10 Cost Implications 25
1.11 Units and Dimensions 26
1.12 Use of Semi-empirical Relations and Graphs 26
1.13 How Do Aircraft Fly? 26
1.13.1 Classification of Flight Mechanics 27
1.14 Anatomy of Aircraft 27
1.14.1 Comparison between Civil and Military Design Requirements 30
1.15 Aircraft Motion and Forces 30
1.15.1 Motion - Kinematics 31
1.15.2 Forces - Kinetics 33
1.15.3 Aerodynamic Parameters - Lift, Drag and Pitching Moment 34
1.15.4 Basic Controls - Sign Convention 34
References 36
2 Aerodynamic and Aircraft Design Considerations 37
2.1 Overview 37
2.2 Introduction 37
2.3 Atmosphere 39
2.3.1 Hydrostatic Equations and Standard Atmosphere 39
2.3.2 Non-standard/Off-standard Atmosphere 47
2.3.3 Altitude Definitions - Density Altitude (Off-standard) 48
2.3.4 Humidity Effects 50
2.3.5 Greenhouse Gases Effect 50
2.4 Airflow Behaviour: Laminar and Turbulent 51
2.4.1 Flow Past an Aerofoil 55
2.5 Aerofoil 56
2.5.1 Subsonic Aerofoil 57
2.5.2 Supersonic Aerofoil 64
2.6 Generation of Lift 64
2.6.1 Centre of Pressure and Aerodynamic Centre 66
2.6.2 Relation between Centre of Pressure and Aerodynamic Centre 68
2.7 Types of Stall 71
2.7.1 Buffet 71
2.8 Comparison of Three NACA Aerofoils 72
2.9 High-Lift Devices 73
2.10 Transonic Effects - Area Rule 74
2.10.1 Compressibility Correction 75
2.11 Wing Aerodynamics 76
2.11.1 Induced Drag and Total Aircraft Drag 79
2.12 Aspect Ratio Correction of 2D-Aerofoil Characteristics for 3D-Finite Wing 79
2.13 Wing Definitions 81
2.13.1 Planform Area, S W 81
2.13.2 Wing Aspect Ratio 82
2.13.3 Wing-Sweep Angle 82
2.13.4 Wing Root (c root) and Tip (c tip) Chords 82
2.13.5 Wing-Taper Ratio, ¿ 82
2.13.6 Wing Twist 82
2.13.7 High/Low Wing 83
2.13.8 Dihedral/Anhedral Angles 83
2.14 Mean Aerodynamic Chord 84
2.15 Compressibility Effect: Wing Sweep 86
2.16 Wing-Stall Pattern and Wing Twist 87
2.17 Influence of Wing Area and Span on Aerodynamics 88
2.17.1 The Square-Cube Law 88
2.17.2 Aircraft Wetted Area (A W) versus Wing Planform Area (S W)89 2.17.3 Additional Wing Surface Vortex Lift - Strake/Canard 90
2.17.4 Additional Surfaces on Wing - Flaps/Slats and High-Lift Devices 91
2.17.5 Other Additional Surfaces on Wing 91
2.18 Empennage 92
2.18.1 Tail-arm 95
2.18.2 Horizontal Tail (H-Tail) 95
2.18.3 Vertical Tail (V-Tail) 96
2.18.4 Tail-Volume Coefficients 96
2.19 Fuselage 98
2.19.1 Fuselage Axis/Zero-Reference Plane 98
2.19.2 Fuselage Length, L fus 98
2.19.3 Fineness Ratio, FR 99
2.19.4 Fuselage Upsweep Angle 99
2.19.5 Fuselage Closure Angle 99
2.19.6 Front Fuselage Closure Length, L f 99
2.19.7 Aft Fuselage Closure Length, L a 99
2.19.8 Mid-Fuselage Constant Cross-Section length, l m 99
2.19.9 Fuselage Height, H 99
2.19.10 Fuselage Width, W 100
2.19.11 Average Diameter, D ave 100
2.20 Nacelle and Intake 100
2.20.1 Large Commercial/Military Logistic and Old Bombers Nacelle Group 101
2.20.2 Small Civil Aircraft Nacelle Position 103
2.20.3 Intake/Nacelle Group (Military Aircraft) 104
2.20.4 Futuristic Aircraft Nacelle Positions 106
2.21 Speed Brakes and Dive Brakes 106
References 106
3 Air Data Measuring Instruments, Systems and Parameters 109
3.1 Overview 109
3.2 Introduction 109
3.3 Aircraft Speed 110
3.3.1 Definitions Related to Aircraft Velocity 111
3.3.2 Theory Related to Computing Aircraft Velocity 112
3.3.3 Aircraft Speed in Flight Deck Instruments 116
3.3.4 Atmosphere with Wind Speed (Non-zero Wind) 117
3.3.5 Calibrated Airspeed 118
3.3.6 Compressibility Correction (¿V c ) 120
3.3.7 Other Position Error Corrections 122
3.4 Air Data Instruments 122
3.4.1 Altitude Measurement - Altimeter 123
3.4.2 Airspeed Measuring Instrument - Pitot-Static Tube 125
3.4.3 Angle-of-Attack Probe 126
3.4.4 Vertical Speed Indicator 126
3.4.5 Temperature Measurement 127
3.4.6 Turn-Slip Indicator 127
3.5 Aircraft Flight-Deck (Cockpit) Layout 128
3.5.1 Multifunctional Displays and Electronic Flight Information Systems 129
3.5.2 Combat Aircraft Flight Deck 131
3.5.3 Head-Up Display (HUD) 132
3.6 Aircraft Mass (Weights) and Centre of Gravity 133
3.6.1 Aircraft Mass (Weights) Breakdown 133
3.6.2 Desirable CG Position 134
3.6.3 Weights Summary - Civil Aircraft 136
3.6.4 CG Determination - Civil Aircraft 137
3.6.5 Bizjet Aircraft CG Location - Classroom Example 138
3.6.6 Weights Summary - Military Aircraft 138
3.6.7 CG Determination - Military Aircraft 138
3.6.8 Classroom Worked Example - Military AJT CG Location 138
3.7 Noise Emissions 141
3.7.1 Airworthiness Requirements 142
3.7.2 Summary 145
3.8 Engine-Exhaust Emissions 145
3.9 Aircraft Systems 146
3.9.1 Aircraft Control System 146
3.9.2 ECS: Cabin Pressurization and Air-Conditioning 148
3.9.3 Oxygen Supply 149
3.9.4 Anti-icing, De-icing, Defogging and Rain Removal System 149
3.10 Low Observable (LO) Aircraft Configuration 150
3.10.1 Heat Signature 150
3.10.2 Radar Signature 150
References 152
4 Equations of Motion for a Flat Stationary Earth 153
4.1 Overview 153
4.2 Introduction 154
4.3 Definitions of Frames of Reference (Flat Stationary E arth) and Nomenclature Used 154
4.3.1 Notation and Symbols Used in this Chapter 157
4.4 Eulerian Angles 158
4.4.1 Transformation of Eulerian Angles 159
4.5 Simplified Equations of Motion for a Flat Stationary Earth 161
4.5.1 Important Aerodynamic Angles 161
4.5.2 In Pitch Plane (Vertical XZ Plane) 162
4.5.3 In Yaw Plane (Horizontal Plane) - Coordinated Turn 164
4.5.4 In Pitch-Yaw Plane - Coordinated Climb-Turn (Helical Trajectory) 165
4.5.5 Discussion on Turn 166
Reference 167
5 Aircraft Load 169
5.1 Overview 169
5.2 Introduction 169
5.2.1 Buffet 170
5.2.2 Flutter 170
5.3 Flight Manoeuvres 171
5.3.1 Pitch Plane (X-Z) Manoeuvre 171
5.3.2 Roll Plane (Y-Z) Manoeuvre 171
5.3.3 Yaw Plane (Y-X) Manoeuvre 171
5.4 Aircraft Loads 171
5.5 Theory and Definitions 172
5.5.1 Load Factor, n 172
5.6 Limits - Loads and Speeds 173
5.6.1 Maximum Limit of Load Factor 174
5.7 V-n Diagram174 5.7.1 Speed Limits 175
5.7.2 Extreme Points of the V-n Diagram 175
5.7.3 Low Speed Limit 177
5.7.4 Manoeuvre Envelope Construction 178
5.7.5 High Speed Limit 179
5.8 Gust Envelope 179
5.8.1 Gust Load Equations 180
5.8.2 Gust Envelope Construction 182
Reference 183
6 Stability Considerations Affecting Aircraft Performance 185
6.1 Overview 185
6.2 Introduction 185
6.3 Static and Dynamic Stability 186
6.3.1 Longitudinal Stability - Pitch Plane (Pitch Moment, M)188
6.3.2 Directional Stability - Yaw Plane (Yaw Moment, N)188
6.3.3 Lateral Stability - Roll Plane (Roll Moment, L)189 6.4 Theory 192
6.4.1 Pitch Plane 192
6.4.2 Yaw Plane 195
6.4.3 Roll Plane 196
6.5 Current Statistical Trends for Horizontal and Vertical Tail Coefficients197 6.6 Inherent Aircraft Motions as Characteristics of Design 198
6.6.1 Short-Period Oscillation and Phugoid Motion 198
6.6.2 Directional/Lateral Modes of Motion 200
6.7 Spinning 202
6.8 Summary of Design Considerations for Stability 203
6.8.1 Civil Aircraft 203
6.8.2 Military Aircraft - Non-linear Effects 204
6.8.3 Active Control Technology (ACT) - Fly-by-Wire 205
References 207
7 Aircraft Power Plant and Integration 209
7.1 Overview 209
7.2 Background 209
7.3 Definitions 214
7.4 Air-Breathing Aircraft Engine Types 215
7.4.1 Simple Straight-through Turbojets 215
7.4.2 Turbofan - Bypass Engine 216
7.4.3 Afterburner Jet Engines 216
7.4.4 Turboprop Engines 218
7.4.5 Piston Engines 218
7.5 Simplified Representation of Gas Turbine (Brayton/Joule) Cycle 219
7.6 Formulation/Theory - Isentropic Case 221
7.6.1 Simple Straight-through Turbojets 221
7.6.2 Bypass Turbofan Engines 222
7.6.3 Afterburner Jet Engines 224
7.6.4 Turboprop Engines 226
7.7 Engine Integration to Aircraft - Installation Effects 226
7.7.1 Subsonic Civil Aircraft Nacelle and Engine Installation 227
7.7.2 Turboprop Integration to Aircraft 229
7.7.3 Combat Aircraft Engine Installation 230
7.8 Intake/Nozzle Design 231
7.8.1 Civil Aircraft Intake Design 231
7.8.2 Military Aircraft Intake Design 232
7.9 Exhaust Nozzle and Thrust Reverser 233
7.9.1 Civil Aircraft Exhaust Nozzles 233
7.9.2 Military Aircraft TR Application and Exhaust Nozzles 233
7.10 Propeller 234
7.10.1 Propeller-Related Definitions 236
7.10.2 Propeller Theory 237
7.10.3 Propeller Performance - Practical Engineering Applications 243
7.10.4 Propeller Performance - Three- to Four-Bladed 246
References 246
8 Aircraft Power Plant Performance 247
8.1 Overview 247
8.2 Introduction 248
8.2.1 Engine Performance Ratings 248
8.2.2 Turbofan Engine Parameters 249
8.3 Uninstalled Turbofan Engine Performance Data - Civil Aircraft 250
8.3.1 Turbofans with BPR around 4 252
8.3.2 Turbofans with BPR around 5-6 252
8.4 Uninstalled Turbofan Engine Performance Data - Military Aircraft 254
8.5 Uninstalled Turboprop Engine Performance Data 255
8.5.1 Typical Turboprop Performance 257
8.6 Installed Engine Performance Data of Matched Engines to Coursework Aircraft 257
8.6.1 Turbofan Engine (Smaller Engines for Bizjets - BPR ~ 4)257 8.6.2 Turbofans with BPR around 5-6 (Larger Jets) 260
8.6.3 Military Turbofan (Very Low BPR)260 8.7 Installed Turboprop Performance Data 261
8.7.1 Typical Turboprop Performance 261
8.7.2 Propeller Performance - Worked Example 262
8.8 Piston Engine 264
8.9 Engine Performance Grid 267
8.9.1 Installed Maximum Climb Rating (TFE 731-20 Class Turbofan) 269
8.9.2 Maximum Cruise Rating (TFE731-20 Class Turbofan) 270
8.10 Some Turbofan Data 272
Reference 273
9 Aircraft Drag 275
9.1 Overview 275
9.2 Introduction 275
9.3 Parasite Drag Definition 277
9.4 Aircraft Drag Breakdown (Subsonic) 278
9.5 Aircraft Drag Formulation 279
9.6 Aircraft Drag Estimation Methodology 281
9.7 Minimum Parasite Drag Estimation Methodology 281
9.7.1 Geometric Parameters, Reynolds Number and Basic C F Determination 282
9.7.2 Computation of Wetted Area 283
9.7.3 Stepwise Approach to Computing Minimum Parasite Drag 283
9.8 Semi-Empirical Relations to Estimate Aircraft Component Parasite Drag 284
9.8.1 Fuselage 284
9.8.2 Wing, Empennage, Pylons and Winglets 287
9.8.3 Nacelle Drag 289
9.8.4 Excrescence Drag 293
9.8.5 Miscellaneous Parasite Drags 294
9.9 Notes on Excrescence Drag Resulting from Surface Imperfections 295
9.10 Minimum Parasite Drag 296
9.11 ¿CDp Estimation 296
9.12 Subsonic Wave Drag 296
9.13 Total Aircraft Drag 298
9.14 Low-Speed Aircraft Drag at Takeoff and Landing 298
9.14.1 High-Lift Device Drag 298
9.14.2 Dive Brakes and Spoilers Drag 302
9.14.3 Undercarriage Drag 302
9.14.4 One-Engine Inoperative Drag 303
9.15 Propeller-Driven Aircraft Drag 304
9.16 Military Aircraft Drag 304
9.17 Supersonic Drag 305
9.18 Coursework Example - Civil Bizjet Aircraft 306
9.18.1 Geometric and Performance Data 306
9.18.2 Computation of Wetted Areas, Re and Basic C F 309
9.18.3 Computation of 3D and Other Effects 310
9.18.4 Summary of Parasite Drag 314
9.18.5 ¿C Dp
Estimation 314
9.18.6 Induced Drag 314
9.18.7 Total Aircraft Drag at LRC 314
9.19 Classroom Example - Subsonic Military Aircraft (Advanced Jet Trainer) 315
9.19.1 AJT Specifications 317
9.19.2 CAS Variant Specifications 318
9.19.3 Weights 319
9.19.4 AJT Details 319
9.20 Classroom Example - Turboprop Trainer 319
9.20.1 TPT Specification 320
9.20.2 TPT Details 321
9.20.3 Component Parasite Drag Estimation 322
9.21 Classroom Example - Supersonic Military Aircraft 325
9.21.1 Geometric and Performance Data for the Vigilante RA-C5 Aircraft 325
9.21.2 Computation of Wetted Areas, Re and Basic C F 326
9.21.3 Computation of 3D and Other Effects to Estimate Component C Dpmin 327
9.21.4 Summary of Parasite Drag 329
Estimation 329
9.21.6 Induced Drag 330
9.21.7 Supersonic Drag Estimation 330
9.21.8 Total Aircraft Drag 332
9.22 Drag Comparison 332
9.23 Some Concluding Remarks and Reference Figures 334
References 338
10 Fundamentals of Mission Profile, Drag Polar and Aeroplane Grid 339
10.1 Overview 339
10.2 Introduction 340
10.2.1 Evolution in Aircraft Performance Capabilities 341
10.2.2 Levels of Aircraft Performance Analyses 342
10.3 Civil Aircraft Mission (Payload-Range) 342
10.3.1 Civil Aircraft Classification and Mission Segments 344
10.4 Military Aircraft Mission 345
10.4.1 Military Aircraft Performance Segments 347
10.5 Aircraft Flight Envelope 349
10.6 Understanding Drag Polar 351
10.6.1 Actual Drag Polar 351
10.6.2 Parabolic Drag Polar 351
10.6.3 Comparison between Actual and Parabolic Drag Polar 352
10.7 Properties of Parabolic Drag Polar 354
10.7.1 The Maximum and Minimum Conditions Applicable to Parabolic Drag Polar 354
10.7.2 Propeller-Driven Aircraft 359
10.8 Classwork Examples of Parabolic Drag Polar 363
10.8.1 Bizjet Market Specifications 363
10.8.2 Turboprop Trainer Specifications 363
10.8.3 Advanced Jet Trainer Specifications 365
10.8.4 Comparison of Drag Polars 366
10.9 Bizjet Actual Drag Polar 366
10.9.1 Comparing Actual with Parabolic Drag Polar 367
10.9.2 (Lift/Drag) and (Mach × Lift/Drag) Ratios 368
10.9.3 Velocity at Minimum (D/V) 369
10.9.4 (Lift/Drag) max , C L @ (L/D)max and V Dmin 369
10.9.5 Turboprop Trainer (TPT) Example - Parabolic Drag Polar 370
10.9.6 TPT (Lift/Drag) max , C L@(L/D)max and V Dmin 370
10.9.7 TPT (ESHP) min_reqd and V Pmin 371
10.9.8 Summary for TPT 372
10.10 Aircraft and Engine Grid 372
10.10.1 Aircraft and Engine Grid (Jet Aircraft) 373
10.10.2 Classwork Example - Bizjet Aircraft and Engine Grid 374
10.10.3 Aircraft and Engine Grid (Turboprop Trainer) 376
References 378
11 Takeoff and Landing 379
11.1 Overview 379
11.2 Introduction 380
11.3 Airfield Definitions 380
11.3.1 Stopway (SWY) and Clearway (CWY) 381
11.3.2 Available Airfield Definitions 382
11.3.3 Actual Field Length Definitions 383
11.4 Generalized Takeoff Equations of Motion 384
11.4.1 Ground Run Distance 386
11.4.2 Time Taken for the Ground Run S G 388
11.4.3 Flare Distance and Time Taken from V R to V 2 388
11.4.4 Ground Effect 389
11.5 Friction - Wheel Rolling and Braking Friction Coefficients 389
11.6 Civil Transport Aircraft Takeoff 391
11.6.1 Civil Aircraft Takeoff Segments 391
11.6.2 Balanced Field Length (BFL) - Civil Aircraft 395
11.6.3 Flare to 35 ft Height (Average Speed Method) 396
11.7 Worked Example - Bizjet 396
11.7.1 All-Engine Takeoff 398
11.7.2 Flare from V R to V 2 398
11.7.3 Balanced Field Takeoff - One Engine Inoperative 399
11.8 Takeoff Presentation 404
11.8.1 Weight, Altitude and Temperature Limits 405
11.9 Military Aircraft Takeoff 405
11.10 Checking Takeoff Field Length (AJT)406 11.10.1 AJT Aircraft and Aerodynamic Data 406
11.10.2 Takeoff with 8° Flap 408
11.11 Civil Transport Aircraft Landing 409
11.11.1 Airfield Definitions 409
11.11.2 Landing Performance Equations 412
11.11.3 Landing Field Length for the Bizjet 414
11.11.4 Landing Field Length for the AJT 416
11.12 Landing Presentation 417
11.13 Approach Climb and Landing Climb 418
11.14 Fuel Jettisoning 418
References 418
12 Climb and Descent Performance 419
12.1 Overview 419
12.2 Introduction 420
12.2.1 Cabin Pressurization 421
12.2.2 Aircraft Ceiling 421
12.3 Climb Performance 422
12.3.1 Climb Performance Equations of Motion 423
12.3.2 Accelerated Climb 423
12.3.3 Constant EAS Climb 425
12.3.4 Constant Mach Climb 427
12.3.5 Unaccelerated Climb 428
12.4 Other Ways to Climb (Point Performance) - Civil Aircraft 428
12.4.1 Maximum Rate of Climb and Maximum Climb Gradient 428
12.4.2 Steepest Climb 432
12.4.3 Economic Climb at Constant EAS 433
12.4.4 Discussion on Climb Performance 434
12.5 Classwork Example - Climb Performance (Bizjet) 435
12.5.1 Takeoff Segments Climb Performance (Bizjet) 435
12.5.2 En-Route Climb Performance (Bizjet) 439
12.5.3 Bizjet Climb Schedule 440
12.6 Hodograph Plot 440
12.6.1 Aircraft Ceiling 443
12.7 Worked Example - Bizjet 443
12.7.1 Bizjet Climb Rate at Normal Climb Speed Schedule 443
12.7.2 Rate of Climb Performance versus Altitude 444
12.7.3 Bizjet Ceiling 444
12.8 Integrated Climb Performance - Computational Methodology 444
12.8.1 Worked Example - Initial En-Route Rate of Climb (Bizjet) 446
12.8.2 Integrated Climb Performance (Bizjet) 447
12.8.3 Turboprop Trainer Aircraft (TPT) 447
12.9 Specific Excess Power (SEP) - High-Energy Climb 447
12.9.1 Specific Excess Power Characteristics 450
12.9.2 Worked Example of SEP Characteristics (Bizjet) 450
12.9.3 Example of AJT 453
12.9.4 Supersonic Aircraft 453
12.10 Descent Performance 454
12.10.1 Glide 457
12.10.2 Descent Properties 458
12.10.3 Selection of Descent Speed 458
12.11 Worked Example - Descent Performance (Bizjet) 459
12.11.1 Limitation of Maximum Descent Rate 460
References 462
13 Cruise Performance and Endurance 463
13.1 Overview 463
13.2 Introduction 464
13.2.1 Definitions 465
13.3 Equations of Motion for the Cruise Segment 466
13.4 Cruise Equations 466
13.4.1 Propeller-Driven Aircraft Cruise Equations 467
13.4.2 Jet Engine Aircraft Cruise Equations 469
13.5 Specific Range 470
13.6 Worked Example (Bizjet) 471
13.6.1 Aircraft and Engine Grid at Cruise Rating 471
13.6.2 Specific Range Using Actual Drag Polar 471
13.6.3 Specific Range and Range Factor 473
13.7 Endurance Equations 478
13.7.1 Propeller-Driven (Turboprop) Aircraft 479
13.7.2 Turbofan Powered Aircraft 480
13.8 Options for Cruise Segment (Turbofan Only) 481
13.9 Initial Maximum Cruise Speed (Bizjet) 487
13.10 Worked Example of AJT - Military Aircraft 488
13.10.1 To Compute the AJT Fuel Requirement 488
13.10.2 To Check Maximum Speed 488
References 489
14 Aircraft Mission Profile 491
14.1 Overview 491
14.2 Introduction 492
14.3 Payload-Range Capability 493
14.3.1 Reserve Fuel 493
14.4 The Bizjet Payload-Range Capability 495
14.4.1 Long-Range Cruise (LRC) at Constant Altitude 496
14.4.2 High-Speed Cruise (HSC) at Constant Altitude and Speed 500
14.4.3 Discussion on Cruise Segment 501
14.5 Endurance (Bizjet) 502
14.6 Effect of Wind on Aircraft Mission Performance 502
14.7 Engine Inoperative Situation at Climb and Cruise - Drift-Down Procedure 503
14.7.1 Engine Inoperative Situation at Climb 503
14.7.2 Engine Inoperative Situation at Cruise (Figure 14.5)504 14.7.3 Point of No-Return and Equal Time Point 505
14.7.4 Engine Data 505
14.7.5 Drift-Down in Cruise 505
14.8 Military Missions 506
14.8.1 Military Training Mission Profile - Advanced Jet Trainer (AJT) 506
14.9 Flight Planning by the Operators 507
References 508
15 Manoeuvre Performance 509
15.1 Overview 509
15.2 Introduction 509
15.3 Aircraft Turn 510
15.3.1 In Horizontal (Yaw) Plane - Sustained Coordinated Turn 510
15.3.2 Maximum Conditions for Turn in Horizontal Plane 516
15.3.3 Minimum Radius of Turn in Horizontal Plane 517
15.3.4 Turning in Vertical (Pitch) Plane 517
15.3.5 In Pitch-Yaw Plane - Climbing Turn in Helical Path 519
15.4 Classwork Example - AJT 520
15.5 Aerobatics Manoeuvre 522
15.5.1 Lazy-8 in Horizontal Plane 523
15.5.2 Chandelle 524
15.5.3 Slow Roll 524
15.5.4 Hesitation Roll 524
15.5.5 Barrel Roll 525
15.5.6 Loop in Vertical Plane 525
15.5.7 Immelmann - Roll at the Top in the Vertical Plane 526
15.5.8 Stall Turn in Vertical Plane 527
15.5.9 Cuban-Eight in Vertical Plane 527
15.5.10 Pugachev's Cobra Movement 528
15.6 Combat Manoeuvre 528
15.6.1 Basic Fighter Manoeuvre 528
15.7 Discussion on Turn 530
References 531
16 Aircraft Sizing and Engine Matching 533
16.1 Overview 533
16.2 Introduction 534
16.3 Theory 535
16.3.1 Sizing for Takeoff Field Length - Two Engines 536
16.3.2 Sizing for the Initial Rate of Climb (All Engines Operating) 539
16.3.3 Sizing to Meet Initial Cruise 540
16.3.4 Sizing for Landing Distance 540
16.4 Coursework Exercises: Civil Aircraft Design (Bizjet) 541
16.4.1 Takeoff 541
16.4.2 Initial Climb 542
16.4.3 Cruise 542
16.4.4 Landing 543
16.5 Sizing Analysis: Civil Aircraft (Bizjet) 543
16.5.1 Variants in the Family of Aircraft Design 544
16.5.2 Example: Civil Aircraft 545
16.6 Classroom Exercise - Military Aircraft (AJT) 546
16.6.1 Takeoff 546
16.6.2 Initial Climb 546
16.6.3 Cruise 547
16.6.4 Landing 548
16.6.5 Sizing for Turn Requirement of 4 g at Sea-Level 548
16.7 Sizing Analysis - Military Aircraft 551
16.7.1 Single Seat Variants 552
16.8 Aircraft Sizing Studies and Sensitivity Analyses 553
16.8.1 Civil Aircraft Sizing Studies 553
16.8.2 Military Aircraft Sizing Studies 554
16.9 Discussion 554
16.9.1 The AJT 557
References 558
17 Operating Costs 559
17.1 Overview 559
17.2 Introduction 560
17.3 Aircraft Cost and Operational Cost 561
17.3.1 Manufacturing Cost 563
17.3.2 Operating Cost 565
17.4 Aircraft Direct Operating Cost (DOC) 567
17.4.1 Formulation to Estimate DOC 569
17.4.2 Worked Example of DOC - Bizjet 571
17.5 Aircraft Performance Management (APM) 574
17.5.1 Methodology 576
17.5.2 Discussion - the Broader Issues 577
References 577
18 Miscellaneous Considerations 579
18.1 Overview 579
18.2 Introduction 579
18.3 History of the FAA 580
18.3.1 Code of Federal Regulations 582
18.3.2 The Role of Regulation 582
18.4 Flight Test 583
18.5 Contribution of the Ground Effect on Takeoff 585
18.6 Flying in Adverse Environments 586
18.6.1 Adverse Environment as Loss of Visibility 586
18.6.2 Adverse Environment Due to Aerodynamic and Stability/Control Degradation 587
18.7 Bird Strikes 590
18.8 Military Aircraft Flying Hazards and Survivability 591
18.9 Relevant Civil Aircraft Statistics 591
18.9.1 Maximum Takeoff Mass versus Operational Empty Mass 591
18.9.2 MTOM versus Fuel Load, M f 592
18.9.3 MTOM versus Wing Area, S W 593
18.9.4 MTOM versus Engine Power 594
18.9.5 Empennage Area versus Wing Area 595
18.9.6 Wing Loading versus Aircraft Span 597
18.10 Extended Twin-Engine Operation (ETOP) 597
18.11 Flight and Human Physiology 598
References 599
Appendices Appendix A Conversions 601
Appendix B International Standard Atmosphere Table 605
Appendix C Fundamental Equations 609
Appendix D Airbus 320 Class Case Study 615
Appendix E Problem Sets 627
Appendix F Aerofoil Data 647
Index 655
Road Map of the Book
Organization
In a step-by-step manner, I have developed a road map to learning industry standard aircraft performance methodology that can be followed in classrooms. Except for Chapter 1, the book is written in formal third-person grammatical usage. The chapters are arranged quite linearly, and there is not much choice in tailoring a course. While the course material progresses linearly, the following diagram depicts how the topics are interlinked.
Chapter 1 introduces some background material to prepare readers on the scope of aeronautical engineering. It gives broad coverage of some historical perspective, future trends, role of marketing, project phases from conception to completion, role of airworthiness requirements, and some miscellaneous topics. The main purpose of this chapter is to motivate readers to explore and learn about aircraft.
Chapter 2 covers atmosphere, aircraft aerodynamics and design considerations that influence aircraft performance and must be known to the engineers. This is the only chapter that could be browsed, as these topics are normally covered separately in academies. Chapter 3 introduces the definitions of various kinds of aircraft velocities, related topics on static stability, and some related flight deck instruments. The equations of motion for a flat stationary Earth are derived in Chapter 4, and classroom work starts from here. Next, the aircraft load limits are introduced in Chapter 5, as these define the aircraft performance envelope. Stability considerations are dealt with in Chapter 6; understanding aircraft stability is essential to performance analyses. Aircraft performance computations cannot start without engine performance data, and they are dealt with in Chapters 7 and 8. Aircraft drag data is evaluated in Chapter 9.
Chapters 10 to 15 present the core treatment of aircraft performance. Aircraft sizing and engine matching are done by aircraft performance engineers, and dealt with in Chapter 16 in a formal manner after completing studies on performance. The methodology is treated uniquely in close conformation with industry practices, and is an indispensable part of analyses at the conceptual design phase of a project, as it finalizes aircraft configuration and demonstrates compliance with customer specifications. The procedure offers a "satisfying" solution to generating a family of aircraft variants. This approach is widely practised by all major aircraft manufacturing organizations. The chapter also permits parametric sensitivity studies, which will eventually prove the key to success through balancing comfort with cost in a fiercely competitive market. Readers are encouraged to study aircraft design considerations along with performance analyses. It is to be stressed all the time that aircraft safety is never compromised. Each chapter starts with an overview, a summary of what is learnt, and the classroom work content.
Direct operating cost estimates are looked at in Chapter 17. For commercial aircraft the economic factors are the most important considerations, and for military aircraft it is the performance. Safety and reliability is never sacrificed. The importance of developing the configurations in a family concept is emphasized. The variants can emerge at a low cost by retaining component commonality and covering a wider market area: one might say, lightheartedly, "Design one and get the second at half the development cost". Finally, Chapter 18 concludes by discussing some miscellaneous topics related to aircraft performance.
Appendices A and B give the conversion factors and the ISA day atmospheric tables for both the SI and Imperial systems. Appendix C covers some important formulae. Appendix D gives a basic review on matrices and determinants required to study equations of motion and some important equations. Appendix E gives the problem sets for the pertinent chapters. It is recommended that these should be worked out. Appendix F gives a case study of the class Airbus 320 aircraft. Finally, Appendix G considers some interesting aerofoil in wide usage. This book is meant to reflect what aircraft performance engineers do in industry and airline operation.
Jane's Aircraft Manual [1] is an indispensable book for the vital statistics of aircraft geometries, design data and relevant performance details. This yearly publication has served many generations of aeronautical engineers around the world for more than half a century. The data from Jane's Aircraft Manual can be used to compare classroom work on similar types of aircraft. Flightglobal.com is another good source to study cutaway diagrams of aircraft and engines. Products from different origins do show similarities, and this is picked up as a strong statistical pattern, which can help to give an idea of what is to be expected in a new design (Section 18.9). Readers should prepare their own statistics for the type of aircraft under study. Other useful publications are [2] to [5]. I would recommend the readers to look at the Virginia Tech web site on Aircraft Design Bibliographies [6]. Their compilation of aircraft design information sources is comprehensive. Related web sites also give useful data.
Many categories of aircraft have been designed. I have chosen the important ones that will broadly cover a wide range of classroom exercises; these will provide adequate exposure for the students. The associated examples in the book would be those of four cases: (i) a turbofan powered Learjet 45 class business jet (Bizjet); (ii) a turboprop powered propeller-driven Tucano class military trainer aircraft (TPT); (iii) a military advanced jet trainer (AJT) in the class of BAe Hawk that has a close support role variant; and (iv) performance computation of a high subsonic jet in the class of Boeing 737/Airbus 320 aircraft is given in Appendix E. These are the types recommended as the most suitable for classroom projects. Classroom methodology should be in harmony with industrial practices, otherwise the gap between academy and industry might widen.
Case studies are indispensable in the course of learning in the classroom. Example exercises must bear high fidelity with the real ones - I take some satisfaction in providing real world examples modified to classroom usage to maintain commercial confidence. These are not from any academic projects, but follow the designs of the real ones worked out by myself. At this point, I highlight that the results are not those from the industry, but have been compared with the performance data available. Industry is not liable for what I present here.
The book gives full coverage of worked-out examples. Instructors have the flexibility to generate problem assignment sets at the level of class requirements. I strongly recommend the adoption of manual computation, leaving the repetitive aspects to spreadsheets to be developed by the students as part of their learning process. This is essential if students are to develop a feel for numbers and to learn the labour content of a design (it is expensive to make mid-course changes). Also, extensive theoretical treatment is embedded for research workers to extend their analytical work. It is common nowadays to provide CDs as companion software. I have elected not to follow this practice because the supplied software to handle repetitive tasks constrains students to interact more deeply with the governing equations, which is an important part of the learning experience.
If students elect to use off-the-shelf software, then let it be the reputable ones. However, these are more meaningful after the subject is well understood, that is, after completing the course with manual computation. This will lead to an appreciation of how realistic the computer output is and how to make changes in input to improve results. It is better to postpone the usage of aircraft performance software until one joins industry. In academia, a student can use computational fluid dynamics (CFD) and finite element method (FEM) analyses as computer-aided engineering (CAE). Today's students are proficient with computers and can generate their own programs.
Suggested Structure for the Coursework
The author suggests a typical pathway for one term of 36 hours of classroom contact hours - 24 hours of lectures and 12 hours of tutorials. [A note of caution: what is done in about 36 hours of classroom lectures takes about 36 weeks in industry.]
Classroom lecture(contact) hours 1. Coverage of Chapter 1 and some topics from Chapter 2 as selected by the instructor (other topics are to be sandwiched as and when required). 1 2. Chapter 3 - to cover velocities, stability criteria, etc. 1.5 3. Equation of motion - Chapter 4. 2 4. Aircraft load - Chapter 5. 1 5. Air stability, weights and CG - Chapter 9. 0.5 6. Engine performance (establish engine data) - Chapters 7 and 8. 2.5 7. Drag estimation - Chapter 9. 2 8. Fundamentals of aircraft...
