Reference Material for a Proposed Formation Flight System J.-B. Brachet, R. Cleaz, A. Denis, A. Diedrich, D. King, P. Mitchell, D. Morales, J. Onnée, T. Robinson, O. Toupet, B. Wong∗ Department of Aeronautics and Astronautics Massachusetts Institute of Technology Cambridge, MA 02139 ∗ Graduate students. This paper is an outgrowth of the spring 2004 Air Transportation Systems Architecting subject. 1 J.-B. Brachet, R. Cleaz, A. Denis, A. Diedrich, D. King, P. Mitchell, D. Morales, J. Onnée, T. Robinson, O. Toupet, B. Wong Table of Contents I. Formation Flight Aerodynamics and Performance ...................................................5 A. Naturally occurring examples ..............................................................................6 B. Aerodynamic background ....................................................................................7 C. Performance benefits from formation flight..........................................................8 D. The theoretical “sweet spot” ..............................................................................10 E. Transport Aircraft Wake ....................................................................................11 F. The real sweet spot and potential benefits ..........................................................12 G. Station-keeping precision...................................................................................14 H. Shape of the formation.......................................................................................16 II. General study of the dynamics and stability of an aircraft in formation flight .........21 A. Introduction .......................................................................................................22 B. Experimental results of the formation flight dynamics .......................................25 C. Configuration proposal ......................................................................................27 III. Commercial Cargo Market, Needs, and Metrics .................................................31 A. Current State of the Market................................................................................32 B. Predicted Market Growth...................................................................................32 C. Predicted Air Cargo Fleet Growth......................................................................33 D. Current Transport System ..................................................................................35 E. Existing Aircraft ................................................................................................36 F. Possible Route Comparisons ..............................................................................36 IV. Military Cargo Market, Needs, and Metrics .......................................................41 A. Introduction .......................................................................................................42 B. Value .................................................................................................................42 C. Existing Airlift Fleet and Structure.....................................................................44 D. Missions ............................................................................................................47 V. UAV’s Market, Needs, and Metrics .......................................................................55 A. The market.........................................................................................................56 B. Mission profiles .................................................................................................56 C. The advantages ..................................................................................................57 D. The disadvantages..............................................................................................57 E. Conclusion.........................................................................................................57 VI. Competing Systems / Vehicles...........................................................................60 A. Systems overview ..............................................................................................61 B. Market overview................................................................................................63 C. Customers..........................................................................................................67 D. Conclusion.........................................................................................................69 VII. Autonomous Flight Control and Software ..........................................................72 A. Guidance Approaches ........................................................................................73 B. Control-Configured Vehicles .............................................................................75 C. String Stability...................................................................................................75 D. Autopilot & Software Capabilities .....................................................................75 VIII. Extremum-Seeking Control for Formation Flight ...............................................80 A. Introduction .......................................................................................................81 2 J.-B. Brachet, R. Cleaz, A. Denis, A. Diedrich, D. King, P. Mitchell, D. Morales, J. Onnée, T. Robinson, O. Toupet, B. Wong B. Architecture .......................................................................................................82 C. Conclusion.........................................................................................................83 IX. Position and Velocity Estimation & Intra-formation Communications ...............86 A. Introduction .......................................................................................................87 B. Position and Velocity Estimation .......................................................................87 C. Intra-formation Communications: Mediums.......................................................92 D. Intra-formation Communications: Network Structures .......................................97 E. Data-rate available...........................................................................................101 X. Human Factors ....................................................................................................104 A. Impact of the Mission: .....................................................................................105 B. Human physiological and cognitive capabilities ...............................................106 C. Socio-cultural and regulatory concerns: ...........................................................109 D. Economic concerns:.........................................................................................109 E. Architecture Impact: ........................................................................................109 F. Human Interface: .............................................................................................110 XI. Multidisciplinary System Design Methods.......................................................116 A. Introduction .....................................................................................................117 B. Elements of MDO............................................................................................117 C. Mathematical formulation ................................................................................118 D. History.............................................................................................................119 E. Advantages of MDO ........................................................................................120 F. Disadvantages of MDO....................................................................................120 G. Available Techniques.......................................................................................120 H. MDO Applied to Formation Flight...................................................................121 I. Conclusion.......................................................................................................122 XII. Key Trade-Off’s ..............................................................................................124 A. Precision..........................................................................................................125 B. System Integration Level .................................................................................126 C. Shape of the Formation ....................................................................................126 D. ATC separation buffer .....................................................................................127 E. Number of Parallel Runways ...........................................................................128 F. Type and Number of Aircraft Certified to Fly in Formation .............................128 XIII. Architecture Selection......................................................................................130 A. Control Methodology.......................................................................................132 B. Communications Equipment ............................................................................137 C. Topology .........................................................................................................138 D. Data Flow ........................................................................................................139