Off-Design Mission Example

The off-design mission example here demonstrates the capability in the height energy formulation, using the level 2 interface. By default Aviary uses a height-energy formulation unless you have specified otherwise. Running a sizing mission followed by running fallout and alternate missions on the sized aircraft will be presented. An overview of off-design missions is presented in Off-Design Mission User Guide.

The example is available in aviary/examples/run_off_design_example.py It uses the run_level2_example.py script and additionally runs two off-design missions.

The results of the sizing problem are saved using prob.save_sizing_to_json(). By default, this method saves the results to sizing_problem.json but the name of the file may be changed using the json_filename argument. The saved problem may then be used to run off-design missions using prob.fallout_mission() and prob.alternate_mission().

This example can be modified to use the 2DOF formulation by using aircraft_for_bench_GwGm instead of aircraft_for_bench_FwFm and import the default 2DOF phase_info (aviary/models/missions/two_dof_default.py) instead of the phase_info declared in the problem.

The methods used to run the off-design missions accept a variety of arguments including phase_info, some mission configuration variables such as equations_of_motion, and inputs that depend on the type of mission being run such as payload, passenger count, and range. If these values are not specified, the same values as the design mission are used by default.

The expected result is that specified variables, such a new payload, passenger count, or range, are reflected in the results of the off-design mission. Variables that should not change, such as takeoff gross mass, or other Design values, are also printed to demonstrate that they remain unchanged. This proves that the aircraft was not resized and instead was only flown on a new mission.

When looking at the specific variables that were selected for printing in this example, design values represent the values used to size the aircraft, while the summary values represent the values used in the specific mission that was run.