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/off_design_example.py The examples start with run_aviary_example.py and add 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/interface/default_phase_info/two_dof.py) instead of the phase_info declared in the problem.

The methods used to run the off-design missions accept the mission parameters payload_mass, mission_range, mission_mass, and phase_info as inputs depending on the type of mission being run. If these values are not specified, the same values as the design mission are used by default. For this example, we simply run a fallout and alternate mission with those default values. The expected result is that the range for the fallout mission and the mission mass for the alternate will be the same as the values computed by the sizing mission.

The results of this study are output after interrogating the problem objects.

Sizing Results

Design Range = 3375. Design Gross mass = 175871.01115631 Summary Gross mass = 175871.01115631

Fallout Results

Summary Range = 3375.00699084 Design Gross mass = 175871.01115631 Summary Gross mass = 175871.01115631

Alternate Results

Summary Range = 3375. Design Gross mass = 175871.01115631 Summary Gross mass = 175869.64047452

In these results, design values represent the values used to size the aircraft, while the summary values represent the values used in the specific mission that is run. We can see that the results are almost identical as expected.