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Meeting	ACGS Committee Meeting 98 - Williamsburg - October 2006
Agenda Location	4 GENERAL COMMITTEE TECHNICAL SESSION 4.2 Research Institutions, Industry and University Reports 4.2.1 Universities 4.2.1.2 Old Dominion University
Title	Old Dominion University
Presenter	Brett Newman
Available Downloads*	presentation
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Abstract	Modeling, analysis, and synthesis of a propeller subsystem for application to ultra-long duration balloon (ULDB) trajectory steering is considered. The ULDB configuration is a constant volume, large diameter lobed spheroid balloon with under slung gondola containing the scientific payload, flight computer, telemetry unit, solar collector, and propulsion device, that is to be floated above 100,000 ft altitude. Propulsive force will be used for small meridional wind disturbance rejection and cross track trajectory steering. Design requirements include constraints on power consumption, thrust generation, and propeller dimension, while design freedoms available for selection are airfoil shape, propeller diameter, aspect ratio, twist profile, number of blades, and propeller turn rate. Float altitude is a mission dependent parameter. A critical factor in the study is identification, utilization, and optimization of subcritical Reynolds number airfoil behavior where laminar flow separation is present and dominant. Blade element theory with effects from induced velocity, nonlinear aerodynamics, and finite span blade tip losses is utilized. A family of four airfoil sections including thin symmetric, thin cambered, flat plate, and curved plate sections are considered. Thin cambered and curved plate airfoil sections provide an ability to meet the design requirements across a significant portion of the altitude envelope. If carefully designed, results indicate that ULDB propulsion controllability objectives are within reach using low risk concepts. Trajectory Management Concepts for Future Small Aircraft Transportation Systems: Methodology for construction and implementation of inflight trajectory management systems for vehicles participating in future small aircraft transportation systems (SATS) is considered. The SATS concept is a modern regional airspace system exploiting integration of key airborne and ground infrastructure technologies to facilitate efficiency and safety improved operations at non-controlled public use airports. An area where new trajectory management guidance systems may provide significant benefit is the transition between en route flight and the terminal airspace boundary, or possibly interior terminal airspace navigation fix points, for both approach and departure. Energy state theory and space-time curve geometry are investigated as tools for tailoring time-to-interface or time-to-land with traffic constraints. Results imply the trajectory management concepts offer significant design freedom to tailor flight paths and vehicle states for optimum performance and safety in real-time. This strategy will also tend to provide practical trajectory profiles while avoiding heavy computational burdens.