Update Calculation and name for Mission.USEFUL_LOAD

[cmbenne3]

Desired capability or behavior.

Mission.USEFUL_LOAD variable is misnamed.
If we want to calculate and display USEFUL_LOAD for the user it should be a property of the sized aircraft and calculated as Aircraft.Design.USEFUL_LOAD = Aircraft.Design.GROSS_MASS - Aircraft.Design.EMPTY_MASS
This quantity seems most useful for aircraft manufacturers trying to sell their aircraft to customers!

We currently have Mission.USEFUL_LOAD summing an intermediate bunch of weights equal to operating_mass - empty mass.
This group of weights may not need to be summed or in the hierarchy, but for consistency with rest of components could be named Mission.OPERATING_LOAD (and Mission.Design.OPERATING_LOAD if required to be saved for the sizing mission).

The current list of things that go into this quantity are:

• cabin_crew_mass
• flight_crew_mass
• unusable_fuel_mass
• oil_mass
• pass_service_mass
• cargo_container_mass

It's basically 'stuff you need to add to the dry empty weight of the aircraft after it leaves the factory to enable operation of the aircraft on the planned mission'.

Is your feature request related to a problem? Please describe.

No response

Associated Bug Report

No response

[jkirk5]

I am ok with adding in the missing parts of useful load to that variable. We'll have to update tests that check the useful load summation component to include those missing parts. The group of masses currently defined as "useful load" don't need their own intermediate calculation, but it does make the operating mass component much cleaner, and potentially sharable across all mass methods - there are probably several summation components that could do that now that I'm thinking about it)

[jkirk5]

The mass report will need to get updated too!