THE UNIVERSITY OF QUEENSLAND Bachelor of Engineering Thesis Fixed-Wing UAV Airframe Design and Validation Student Name: Timothy Brown Course Code: MECH4500 Supervisor: Dr Ingo Jahn Submission Date: 25 October 2018 A thesis submitted in partial fulfilment of the requirements of the Bachelor of Engineering Degree in Mechanical and Aerospace Engineering UQ Engineering Faculty of Engineering, Architecture and Information Technology Acknowledgements Firstly, I would like to express my gratitude to my supervisor, Dr. Ingo Jahn for allowing me to undertake this thesis. I am also grateful for the consistent help and guidance he has provided over the course of the project, as both his knowledge and wisdom know no insurmountable obstacle I would like to thank my parents for their constant support during over the course of the project, with many long days and sleepless nights supported by their continual efforts. I would also like to extend my thanks to Matthew Miotto and Christopher Voller. Their continual willingness to listen to and help solve problems over the long time I have known them cannot be understated, with much beneficial knowledge often gained as a result of their insights. I would also like to thank the lecturers and tutors who have helped me over the course of my time at the university, whose continual efforts to further the knowledge of others has allowed me to grow my skillset and hone my skills. Finally, I would like to acknowledge the friends that I have known for years, and those I have made during my time at university. These last four years have certainly been made much more interesting with everyone around, and their continual support often provides strength in times of hardship. ii Abstract In recent years, UAVs have become widely adopted in numerous fields. However, the costs associated with designing and building UAVs, even for hobbyists, are prohibitively expensive. A free tool that could enable the rapid preliminary design, optimisation and feasibility estimation of a vehicle would prove to be very useful for reducing the cost of entry of UAVs. Simulation software was created based upon research conducted into the performance of UAVs in the areas of aerodynamics, engine and propeller performance. This software has the ability to simulate a large number of designs quickly, as well as conducting automatic sensitivity analyses and optimisation processes for a range of designs and missions (see Appendix U for a link to the software). Validation of the simulation software was conducted in three main steps. Firstly, real UAVs were imported into the software and tested. Secondly, an optimisation process was conducted to analyse the results provided. Finally, off-design analyses were conducted for the optimised design and mission to investigate the variations in performance. The real UAVs were found to be in good agreement with their simulated counterparts, especially given the assumptions made. The results obtained from the optimisation and off-design analyses were also in-line with the results predicted by literature, validating the correct functionality and accuracy of the simulation software. Additional complex combi- nations of effects were also found to arise during operation, providing further validation for the simulation software. Overall, the simulation software created has large potential for future improvements while showing good validity and accuracy at its current iteration. It is able to provide insight into both simple and complex effects associated with the aerodynamics and engine/pro- peller performance of a UAV, and will serve as a useful platform to build upon in the future. Therefore, through the development of the capability to automatically simulate and optimise UAV designs and insight into the performance of fixed-wing UAVs, the accessibility of UAV design has been expanded. iii Table of Contents Acknowledgements ii Abstract iii Table of Contents iii List of Tables vii List of Figures viii Nomenclature 1 1 Introduction 2 1.1 Project Outline . .3 1.2 Scope . .4 1.3 Objectives . .5 2 Literature Review 6 2.1 Past UAVs . .6 2.2 Alternate Design and Simulation Options . .7 2.3 Wing Parameters . .9 2.4 Propulsion . 15 2.5 Fuselage Data Source . 17 2.6 Mass Data Sources . 18 3 Methodology 19 3.1 Simulation Scope . 19 3.2 Equations of Flight . 20 3.3 Simulation Creation . 22 3.4 Simulation Data Flow . 23 3.5 Choices Made . 26 4 Validation 29 4.1 Performance of Real UAVs . 29 4.1.1 Limitations of Validation . 29 4.1.2 MQ-1B Predator . 30 4.1.3 Aerosonde . 37 4.1.4 ScanEagle . 43 4.1.5 Overall Real UAV Performance Analysis . 47 4.2 Example Design Process . 48 4.2.1 Pre-Simulation . 48 4.2.2 Optimisation Process . 50 iv 4.2.3 Final Results . 56 4.3 Off-Design Performance . 58 4.3.1 Design Variations . 58 4.3.2 Mission Variation . 67 5 Discussions and Recommendations 71 5.1 Trends Observed . 71 5.2 Problems Encountered . 74 5.3 Validity . 76 5.3.1 Performance of Real UAVs . 76 5.3.2 Example Design Process . 77 5.3.3 Off-Design Performance . 77 5.3.4 Overall Validity . 78 5.4 Future Potential . 79 5.5 Recommendations . 80 6 Conclusions 82 6.1 Contributions . 82 Appendices 88 A Example of the Effect of Wing Position 88 B Effective Flow Velocity Over a Swept Wing 88 C Supersonic Flow Over a Wing 89 D Example of the Effect of Wing Sweep 89 E Dutch Roll 90 F Effect of Wing Dihedral on Lateral Stability 91 G Wing Twisting 91 H Effects of Leading and Trailing Edge Flaps and Slots 92 I Effect of Wing Taper on Lift Distribution and Local Coefficient of Lift 93 J Variable-Pitch Propeller Performance Curves 94 K Code Description 95 L Forces on an Airbourne Fixed-Wing UAV 96 M Spherically Blunt Tangent-Ogive Nose Projectile 96 v N MQ-1B Dimensions 97 O MQ-1B Discretization 97 P Aerosonde Discretization 98 Q ScanEagle Discretization 98 R Example Design Process Mission 99 S Example Design Process Baseline Design 99 T Off-Design Mission Variation Mission File 100 U Simulation Code 101 U.1 Angsolver . 101 U.2 Batch . 101 U.3 Cogen . 103 U.4 Compiler . 105 U.5 Controlgen . 105 U.6 Controller . 106 U.7 Code: Convert . 110 U.8 Csolver . 111 U.9 Designparam . 111 U.10 Efficientflight . 113 U.11 Enviro . 115 U.12 Interpos . 116 U.13 Ldgen . 120 U.14 Massfinder . 121 U.15 Missionpath . 123 U.16 Resultsprocessing . 124 U.17 Sensitivity . 129 U.18 Side . 134 U.19 Tables . 135 vi List of Tables 4.1.1 MQ-1B physical and performance characteristics. 30 4.1.2 Performance characteristics of the real and simulated MQ-1B. 31 4.1.3 Aerosonde physical and performance characteristics. 37 4.1.4 Performance characteristics of the real and simulated Aerosonde. 37 4.1.5 ScanEagle physical and performance characteristics. 43 4.1.6 Performance characteristics of the real and simulated ScanEagle. 44 4.2.1 Optimised design parameters. 56 4.3.1 Results from the off-design design variation analysis. 58 K.1 Description of modules used within the simulation. 95 List of Figures 3.4.1 Flowchart for data within the simulation. 23 4.1.1 MQ-1B combined efficiency performance map. 32 4.1.2 MQ-1B propeller efficiency map. 32 4.1.3 MQ-1B lift/drag ratio performance map. 33 4.1.4 MQ-1B engine power performance map based on craft mass and angle of attack. 35 4.1.5 MQ-1B engine power performance map based on craft mass and velocity. 35 4.1.6 Aerosonde performance map based on craft angle of attack and mass. 40 4.1.7 Aerosonde performance map based on craft velocity and mass. 40 4.1.8 Aerosonde performance map based on craft velocity and angle of attack. 41 4.1.9 ScanEagle performance map based on craft angle of attack and mass. 45 4.1.10 ScanEagle performance map based on craft velocity and mass. 45 4.1.11 ScanEagle performance map based on craft angle of attack and velocity. 46 4.2.1 Results of the first simulation (fuselage only). 51 4.2.2 Results of the second simulation (fuselage only). 52 4.2.3 Results of the third optimisation (wings only). 53 4.2.4 Results of the fourth optimisation (wings only). 54 4.2.5 Results of the fifth optimisation (wings and fuselage). 55 4.3.1 Performance map of the "big fuselage" design. 59 4.3.2 Performance map of the "small fuselage" design. 60 4.3.3 Performance map of the "big wing" design. 61 4.3.4 Performance map of the "small wing" design. 62 4.3.5 Lift-to-drag ratio of the NACA 4510 airfoil. 63 4.3.6 Performance map for the "heavy" design. 64 4.3.7 Performance map of the "light" design. 65 4.3.8 Flight parameters over the course of a mission. 67 4.3.9 Lift-to-drag ratio of the vehicle at various angles of attack. 68 vii A.1 Effects of wing position on side-slip stability. ..