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OpenMDAO / Aviary

NASA's aircraft analysis, design, and optimization tool
https://openmdao.github.io/Aviary/
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Atmosphere comp defaults to geopotential alt #466

Closed jkirk5 closed 6 days ago

jkirk5 commented 3 months ago

Description

The USatm1976Comp from dymos we are using actually defaults to using geopotential altitude - this may be inconsistent with how we are treating altitude across different subsystems including mission analysis.

Since there is a conversion factor between them, we should be consistent with which altitude we use. Possible further discussion is needed on the merits of geopotential altitude for conceptual design and if we want the option to pick which to use, or globally hardcode Aviary to a specific altitude type.

Components such as table loading (such as in propulsion and aero) need to have the capability to convert altitude type. Propulsion uses the FLOPS equations for geopotential -> geometric altitude, which is inconsistent with the 1976 US atmosphere standard. All components should use the conversion method in the USatm1976Comp for consistency with a published method.

Example

No specific example - any place USatm1976Comp is used in Aviary, the options h_def is not set, which defaults it to geopotential

Aviary Version

0.9.4-dev

Relevant environment information

No response

jkirk5 commented 3 months ago

This will change model results, and therefore should be a part of the next Aviary version (0.9.6). This can be paired with upcoming changes to openMDAO report locations that will similarly change existing models.

It should be merged into the 0.9.6dev branch and NOT main!!

jkirk5 commented 3 weeks ago

When this component gets updated, if only a few tests break we can update their expected values. If a significant number of tests break, we have a couple options we could try, ping me