LIBRARY CRANFIELD UNIVERSITY Spencer Woodford The Minimisation Combat Aircraft Life Cycle Cost of through Conceptual Design Optimisation CRANFIELD COLLEGE OF AERONAUTICS Ph. D. THESIS -It UBFIARY CRANFIELD UNIVERSITY CRANFIELD COLLEGE OF AERONAUTICS Ph. D. THESIS 1999 Spencer Woodford The Minimisation Combat Aircraft Life Cycle Cost of through Conceptual Design Optimisation Supervisor: Dr. Howard Smith May 1999 ABSTRACT In increase has been to the an effort cost-effectiveness of military equipment, a method developed in designs to perform conceptual studies on combat aircraft, resulting of for Life Cycle Cost (LCC). Consequently, the specified capability optimised minimum design loop be being the cost can considered as closed, allowing automated production data for different The of a consistent set of cost and performance aircraft solutions. design informed, design decisions, leading thus to engineer can make unbiased, a more Defence budgets. efficient use of shrinking Because the to the be developed, 'deep of vast scale which cost model could overheads' included, the the tool to the are not restricting use of comparison of similar weapons (combat design systems aircraft), with a common set of objectives and performance The design is based design tool constraints. aircraft conceptual on classical methods, data. The recently adapted and updated, and validated with existing aircraft engine have been developed from detailed thermodynamic performance and sizing modules LCC is different the models, whilst model an amalgamation and update of several for different in life the methods, each written a phase system cycle. The LCC described, tool aircraft synthesis models, opfimisation and algorithms are and The to validation results are presented where possible. software cost model was used design the generate a series of results, mimicking early stages of an aircraft selection demonstration be the trade-off that procedure, and allowing a of various studies can Results from discussed, the performed. selection process are presented and overall drawn, for further Published data for study conclusions arc and areas work suggested. included in Appendices, detailed the together real aircraft and engines are with aircraft data by the parameter and cost output generated model. i This is intentionally blank. page ii ACKNOWLEDGEMENTS The Author like to thank the the Cranfield College Aeronautics for would staff of of their help during the this in the in the Air course of research, particular support staff Vehicle Design Department, Denis Howe, John Fielding, Robert Jones, Alan and Morris, Pericles Pilidis, John Stollery, for in Special their and advice specialist areas. Howard Smith, for his inspiration, thanks to encouragement, guidance, and support through the this whole of research programme. Thanks to: also Jack Mattingly, Seattle University, for for ONx the the of provision of source code and OFFX improvement. thermodynamic their modelling routines, and advice on Jack Vondrell, Wright Patterson Air Force Base, for his help in of gathering and data in Appendix B, from dimension the the validating engine contained which engine developed. and mass prediction methodology was Wendy Kunc, the Office the US Assistant Secretary the Air Force (Financial of of of Management Comptroller), Lisa Johnson TASC, Inc., for and and of confidential USAF Visibility And Management Operation Support Cost the provision of of and (VAMOSC) data USAF and personnel numbers. Tina Colarrosi, US Air Force Cost Analysis Agency, for her help the of on engine drivers production cost and prediction methods. Philip Pugh, formerly MoD Directorate Project, Time, Cost Analysis, for his of of and drivers, discussion Life Cycle Costing. thought-provoking guidance on analysis, and of Tony Gill Andy Clifford, the Defence Evaluation Research Agency, for their and of and feedback during thorough the review and research study. Finally, Vikki, Family Friends, love has been thanks to and my and whose and support 'tricky bits'. through the unwavering iii This is intentionallY blank. page iv TA13LE CONTENTS OF ABSTRACT i .................................................................................................................................. o ...... o ........... ACKNOWLEDEGAIENTS iii ............................................................................................................... o .............. TABLE OF CONTENTS v ......................... o ........ o ....... o ...................................................................................... LIST OF FIGURES ix .................................................................................. o .............. o ..................................... LISTOFTABLESo xi .................................................... ooo.. o.. o ........ oo ............. oo. oo .................................... o .......... NOTATION xiii ..................... o. 0 ...................... o .............. oo.. ooo ................ o ............ o ....... o. o ................. o. o ......... o .... oo. INTRODUCTION I ............................................................................................................................ 1.1 BACKGROUND DEFINITION 2 AND ...................................................................................................... 1.2 RESEARCH JUSTIFICATION 4 .............................................................................................................. 1.3 AiMS OBJECTIVES 8 AND ................................................................................................................... LITERATURE SEARCH 11 .............................................................................................................. 2.1 INTRODUCTION 12 ............................................................................................................................. 2.2 PREVIOUS WORK 12 .......................................................................................................................... 2.3 AREAS STUDY 15 OF .......................................................................................................................... 2.3.1 General Costing Literature 15 ................................................................................................ 2.3.2 A irfram 17 eL ayo ut ................................................................................................................. 2.3.3 Airframe Materials 18 ............................................................................................................. 2.3.4 Propulsion Options 22 ............................................................................................................ 2.3.5 Avionics 28 .............................................................................................................................. 2.3.6 Software 33 .............................................................................................................................. 2.3.7 Reliability Maintainability 36 and .......................................................................................... 2.3.8 Other Data Sources 41 ............................................................................................................ 2.4 SUMMARY 44 .................................................................................................................................... OPTIMISATION PROCESSES AND TOOLS 45 ............................................................................ 3.1 INTRODUCTION 46 ............................................................................................................................. 3.2 LIMITATIONS PITFALLS 47 AND .......................................................................................................... 3.2.1 Discontinuities 47 .................................................................................................................... 3.2.2 Local Minima 49 ..................................................................................................................... 3.3 DESCRIPTION OF RQPMIN 50 ........................................................................................................... 3.3.1 Problem Formulation 50 ......................................................................................................... 3.3.2 Variable Calegorisation 51 ..................................................................................................... 3.3.3 Quantities Calculated by RQPMIN 51 .................................................................................... 3.3.4 Convergence Criteria 52 ......................................................................................................... 3.3.5 Inner Iterations 53 ................................................................................................................... 3.3.6 Newton Iterations 53 ............................................................................................................... 3.3.7 The Minimisation Step 54 ........................................................................................................ 3.3.8 The Feasibility Step 55 ............................................................................................................ 3.3.9 Other Functions 56 .................................................................................................................. 3.3.10 Program Termination 56 ......................................................................................................... 3.4 SUMMARY 57 .................................................................................................................................... PROGRAM STRUCTURE AND AIRFRAME DEFINITION 59 .................................................. 4.1 DESCRIPTION AND OVERALL STRUCTURE 60 ..................................................................................... 4.1.1 File Read Variable Initialisation 61 and ................................................................................. 4.1.2 Component Sizing 61 ............................................................................................................... 4.1.3 Mass Estimation Volume Accounting 62 and .......................................................................... V Contents 4.1.4 Aerodynamic Estimation 62 .................................................................................................... 4.1.5 Propulsion Modelling 62 ......................................................................................................... 4.1.6 Performance Calculations 63 .................................................................................................. 4.1.7 Life Cycle Cost Model 64 ........................................................................................................ 4.1.8 Aircraft Synthesis Output Routines 64 .................................................................................... 4.1.9 Other Modules 65 .................................................................................................................... 4.2 AIRFRAME COMPONENT SIZING 66 .................................................................................................... 4.2.1 Aircraft Description Variables 67 ........................................................................................... 4.2.2 Fuselage Sizing 68 .................................................................................................................. 4.2.3 Wing Sizing 69 ......................................................................................................................... 4.2.4 Sizing Correlations 71 ............................................................................................................. 4.2.5 Empennage Sizing 72 .............................................................................................................. 4.3 MASS ESTIMATION AND VOLUME ACCOUNTING 74 ........................................................................... 4.3.1 Structural Mass Estimation 74 ................................................................................................ 4.3.2 Systems Mass Estimation 76 .................................................................................................... 4.3.3 Mass Estimation Results 78 ..................................................................................................... 4.3.4 Volume 79 accounting ............................................................................................................. 4.4 SUMMARY 82 .................................................................................................................................... 5 AERODYNAMICS AND PROPULSION 83 .................................................................................... 5.1 AERODYNAMIC MODELLING 84 ....................................................................................................... .. 5.1.1 LiftModel 84 ........................................................................................................................... 5.1.2 Angle-of-Attack Model 88 ....................................................................................................... 5.1.3 Drag Model 91 ......................................................................................................................... 5.2 ENGINE MODELLING ROUTINES 98 .................................................................................................. .. 5.2.1 Code Modifications 101 .......................................................................................................... 5.2.2 Engine Design Installation 103 and ........................................................................................ 5.2.3 Off-Design Analysis & Engine Losses 105 . .............................................................................. 5.2.4 Engine Dimensions Mass Estimation III and ........................................................................ 5.3 SummARY 115 .................................................................................................................................. 6 AIRCRAFT POINT AND MISSION PERFORMANCE 117 .......................................................... 6.1 POINT PERFORMANCE CALCULATIONS 118 ........................................................................................ 6.1.1 Take-OffPerformance 119 ...................................................................................................... 6.1.2 Landing Performance 120 ....................................................................................................... 6.1.3 Attained Turn Performance 121 .............................................................................................. 6.1.4 Sustained Turn Performance 122 ............................................................................................ 6.1.5 MachlSpeed Performance 123 ................................................................................................ 61.6 Climb Performance 124 andAcceleration .............................................................................. 6.1.7 Specific Excess Power Constraint 127 .................................................................................... 6.1.8 Calculation Altitude 127 ofMaximum .................................................................................... 6.2 MISSION PERFORMANCE CALCULATIONS 128 .................................................................................... 6.2.1 Engine Start, Warm-up, Taxi, 129 etc . .................................................................................... 6.2.2 Take-Off 129 ........................................................................................................................... 62.3 Change in Energy-Height 130 ................................................................................................. 6.2.4 Cruise 130 ............................................................................................................................... 62.5 Manoeuvres 131 ...................................................................................................................... 6.2.6 Weapons Drop 132 .................................................................................................................. 6.2.7 Loiter / Combat A ir Patrol 132 ............................................................................................... 6.2.8 Landing 133 ............................................................................................................................ 6.2.9 Mission Termination 133 ......................................................................................................... 62.10 Attained & Sustained Turn Data 133 ...................................................................................... 62.11 Post-Mission Calculations Constraint Evaluation 135 and .................................................... 6.3 SUM MARY 137 .................................................................................................................................. vi Contents 7 LIFE CYCLE COST MODEL 139 .................................................................................................... 7.1 DESCRIPTION MODEL STRUCTURE AND 140 ...................................................................................... 7.1.1 Research, Development, Test Evaluation (RDT&E) 140 and .................................................. 7.1.2 Production 140 ........................................................................................................................ 7.1.3 Operation Support (O&S) 140 and ......................................................................................... 7.1.4 Disposal 141 ........................................................................................................................... 7.1.5 Structure Definition 141 .......................................................................................................... 7.2 PARAMETER INITIALISATION 142 ....................................................................................................... 7.2.1 Advanced Technology Factor 142 ..... .................................................................................... 7.2.2 Number 142 ofPartners .......................................................................................................... 7.2.3 A MPR Mass 142 ...................................................................................................................... 7.2.4 Consumer Price Index 143 ...................................................................................................... 7.2.5 Labour Rates 143 .................................................................................................................... 7.2.6 Advanced Materials Factor 144 .............................................................................................. 7.2.7 Collaborative Factor 145 ........................................................................................................ 7.3 RES DEVELOPMENT, TEST, & EVALUATION EARCI I, 146 ................................................................... 7.3.1 Airframe Development 146 ..................................................................................................... 7.3.2 Engine Development 148 ......................................................................................................... 7.3.3 Avionics Development 149 ...................................................................................................... 7.3.4 Total Development 149 ........................................................................................................... 7.4 PRODUCTION 150 .............................................................................................................................. 7.4.1 Airframe Production 150 ......................................................................................................... 7.4.2 Engine Production 151 ............................................................................................................ 7.4.3 Avionics Production 152 ......................................................................................................... 7.4.4 Total Aircraft Production 152 ................................................................................................. 7.4.5 Acquisition Unit Cost Recurring Flyaway Cost 152 and ......................................................... 7.5 GROUND SUPPORT EQUIPMENT INITIAL SPARES 153 AND .................................................................. 7.6 RELIABILITY MAINTAINA131LITY 154 AND .......................................................................................... 7.6.1 Arising Maintenance 155 ........................................................................................................ 7.6.2 Scheduled Maintenance 158 ................................................................................................... 7.63 Total Maintenance Effort 159 ................................................................................................. 7.7 OPERATION AND SUPPORT (O&S) 160 ............................................................................................... 7.7.1 Operation Personnel 160 ........................................................................................................ 7.7.2 Support Personnel 161 ............................................................................................................ 7.7.3 Total Personnel Numbers Cost 162 and .............................................................. ................... 7.7.4 Service Allowances, Personnel Support Training 162 and ..................................................... 7.7.5 Unit Level Consumption 163 .......................................................................... ........................ 7.7.6 Contracts 165 ............................................................................................... .......................... 7.7.7 Sustaining Support 166 ......................................................... ................................................. 7.7.8 Installation Support Funds 167 ...................... ........................................................................ 7.7.9 Total Operation Support Cost 167 and ................................................................................... 7.8 DISPOSAL 168 .................................................................................................................................... 7.9 LIFE CYCLE COST 169 ....................................................................................................................... 7.10 SU MMARY 170 ................................................................................................................................. GENERATION OF RESULTS 171 .................................................................................................... 8.1 INTRODUCTION 172 ........................................................................................................................... 8.1.1 Optimiser Convergence 172 .................................................................................................... 8.1.2 Combat Validation 174 ........................................................................................................... 8.2 PARAMETER DEFINITION 176 ............................................................................................................. 8.2.1 Point Mission Performance Parameters 176 and ................................................................... 8.2.2 Engine Parameters 177 ........................................................................................................... 8.2.3 Procurement Economic Parameters 179 and .......................................................................... 8.3 CONFIGURATION OPTIONS 180 .......................................................................................................... 8.3.1 Single Engine Configurations 180 .......................................................................................... 8.3.2 Twin Engine Configurations 182 ............................................................................................ vii Contents 8.3.3 Single Engine Twin Engine Comparison 184 vs. .................................................................... 8.3.4 Initial Configuration Selection 187 ......................................................................................... 8.3.5 Internal Weapons Carriage 189 .............................................................................................. 8.3.6 Effect Advanced Materials 191 of ........................................................................................... 8.3.7 Influence Objective Function 194 ofthe ................................................................................. 8.3.8 Final Configuration Selection 197 .......................................................................................... 8.3.9 More Electric Aircraft Study 197 ............................................................................................ 8.4 SummARY 202 .................................................................................................................................. 9 DISCUSSION AND CONCLUSIONS 203 ........................................................................................ 9.1 INTRODUCTION 204 ........................................................................................................................... 9.2 FULFILMENT PROJECT AIMS 205 OF ................................................................................................... 9.2.1 Literature Review 205 ............................................................................................................. 9.2.2 Optimisation 205 ............ 9.2.3 Program Structure Definition 206 andAirframe .................................................................... 9.2.4 Aerodynamics Propulsion 206 and ......................................................................................... 9.2.5 Aircraft Point Mission Performance 208 and ......................................................................... 9.2.6 Life Cycle Cost Model 209 ...................................................................................................... 9.2.7 Validation 211 ......................................................................................................................... 9.2.8 Generation 211 ofResults ....................................................................................................... 9.3 AREAS FURTHER WORK 211 FOR ...................................................................................................... 9.3.1 Reliability Maintainability Models 211 and ............................................................................ 9.3.2 Operation Support Contract Costs 212 and ............................................................................ 9.3.3 Improvement Model 212 ofLCC ............................................................................................. 9.3.4 Investigation Software LCC 213 ofA vionics and ................................................................... 9.3.5 Upgrade Engine Modelling Routines 213 the of ..................................................................... 9.3.6 Aircraft 'Advanced Technologies 213 .................................................................................... 9.3.7 Aircraft Synthesis Modifications 213 ...................................................................................... 9.4 CONCLUSIONS 214 ............................................................................................................................. REFERENCES 215 ....................................................................................................................................... APPENDIX A- AIRCRAFT DATA 223 ..................................................................................................... APPENDIX B- ENGINE DATA 225 .......................................................................................................... APPENDIX C- COMBAT OUTPUT DATA 227 ...................................................................................... C. 1 EXAMPLE AIRCRAFT CONFIGURATIONS 227 ...................................................................................... C. 2 SINGLE ENGINE CONFIGURATIONS 231 .............................................................................................. C. 3 TWIN ENGINE CONFIGURATIONS 247 ................................................................................................. CA ADVANCED MATERIALS STUDY 263 .................................................................................................. C. 5 MORE ELECTRIC AIRCRAFT STUDY 277 ............................................................................................ viii