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FBHALE was developed to aid in the conceptual design of High Altitude Long Endurance (HALE) aircraft. By leveraging first order physical models for the various tightly coupled disciplines that drive HALE aircraft design, FBHALE allows for quick and accurate design space exploration. FBHALE is useful for rapid down selection of aircraft configurations and also includes sufficient engineering fidelity for realistic preliminary design analysis enabling shorter development cycles. Physics models includes Low Reynolds number aerodynamics, composite structures, integrated vehicle performance (including solar energy utilization) and their interactions, each captured with an appropriate level of fidelity while maintaining computational efficiency. The image below shows several different aircraft configurations that have been optimized in FBHALE highlighting its versatility.
The framework architecture includes 2 primary loops, the outer optimization loop and the design loop. The outer optimization loop may be described as an optimization problem where design variables are leveraged towards a set of defined objectives while satisfying constraints. The inner design loop is in essence an interconnection of analysis modules that iteratively sizes aircraft subsystems against requirements and determines the properties of the various subsystems. The diagram below illustrates the design flow of the various loops and parameters. Please see the papers in the /Docs folder for additional details on the framework architecture.
HALE appropriate models were developed for each subsystem and component of the design. The papers in the /Docs folder delve into considerable detail on the modeling of each subsystem. Please reference these papers for details and validation. Below is a list of modeling capabilities included in FBHALE.
- Sectional Low Reynolds Aerodynamics
- Lifting Line 3D Aero Representation
- Aircraft Stability (surface sizing / mass placement against requirements)
- Structural Analysis (mass, stiffness distribution, stress recovery, buckling)
- Aero Structural Interactions (flights loads, flutter and divergence)
- Propulsion System, Sizing/Design (motor and propeller)
- Solar Placement Optimization
- Integrated Mission Performance (CONOPs, solar collection)
Four example cases are included in /Runs. These cases highlight the versatility of the framework and provide a good starting point for describing your own aircraft and input set. The input values in these example cases were arbitrarily determined. The papers in the /Docs folder detail some of the key components of these example aircraft including mass breakdowns and drag buildups. Shown below is an example output in the form of Pareto frontiers comparing MGTOW vs latitude for a single boom and dual boom aircraft as well as detailed mass and drag breakdowns for the aircraft on the frontiers at 20 degrees latitude. Using FBHALE, configurations can quickly be traded and preliminary design for individual aircraft can be created.
