Add new variables related to cruise

[xjjiang]

Desired capability or behavior.

GASP has the following variables:

• EMCRU: design cruise Mach number for engine sizing (not mission analysis)
• HNCRU: design cruise altitude in feet
• RWCRTX: ratio of cruise weight to gross weight for propulsion sizing (1.0)
• RCCRU: rate of climb at cruise point

It is recommended that Aviary implement these features.

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

No response

Associated Bug Report

No response

[jkirk5]

I am also marking this one wontfix because we will want to define performance constraints in Aviary in a fundamentally different way via the future Performance subsystem.
See #1058 for similar thoughts