Mission file

A mission file describes precisely one or several missions that could be computed by the performance model fastoad.performances.mission of FAST-OAD.

The file format of mission files is the YAML format. A quick tutorial for YAML (among many ones) is available here

mission description

Mission elements

Type	Parts	Description
segment	N/A	The basic bricks that are provided by FAST-OAD.
phase	segment(s)	A free assembly of one or more segments.
route	zero or more phase(s) one cruise segment zero or more phase(s)	A route is a climb/cruise/descent sequence with a fixed range. The range is achieved by adjusting the distance covered during the cruise part.
mission	routes and/or phases	A mission is what is computed by fastoad.performances.mission. Generally, it begins when engine starts and ends when engine stops.

Phase section

This section, identified by the phases keyword, defines flight phases. A flight phase is defined as an assembly of one or more flight segment(s).

Basically, a phase has a name, and a parts attribute that contains a list of segment definitions.

Nevertheless, it is also possible to set, at phase level, the parameters that are common to several segments of the phase.

The phase section only defines flight phases, but not their usage, that is defined in route and mission sections. Therefore, the definition order of flight phases has no importance.

Example:

phases:
  initial_climb:                                # Phase name
    engine_setting: takeoff                         # ---------------
    polar: data:aerodynamics:aircraft:takeoff       #   Common segment
    thrust_rate: 1.0                                #   parameters
    time_step: 0.2                                  # ---------------
    parts:                                          # Definition of segment list
      - segment: altitude_change                    # 1st segment (climb)
        target:
          altitude:
            value: 400.
            unit: ft
          equivalent_airspeed: constant
      - segment: speed_change                       # 2nd segment (acceleration)
        target:
          equivalent_airspeed:
            value: 250
            unit: kn
      - segment: altitude_change                    # 3rd segment (climb)
        thrust_rate: 0.95                           # phase thrust rate value is overwritten
        target:
          altitude:
            value: 1500.
            unit: ft
          equivalent_airspeed: constant
    climb:                                    # Phase name
      ...                                       # Definition of the phase...

Route section

This section, identified by the routes keyword, defines flight routes. A flight route is defined as climb/cruise/descent sequence with a fixed range. The range is achieved by adjusting the distance covered during the cruise part. Climb and descent phases are computed normally.

A route is identified by its name and has 4 attributes:

• range: the distance to be covered by the whole route

• climb_parts: a list of items like phase : <phase_name>

• cruise_part: a segment definition, except that it does not need any target distance.

• descent_parts: a list of items like phase : <phase_name>

Example:

routes:
  main_route:
    range:
      value: 3000.
      unit: NM
    climb_parts:
      - phase: initial_climb
      - phase: climb
    cruise_part:
      segment: cruise
      engine_setting: cruise
      polar: data:aerodynamics:aircraft:cruise
      target:
        altitude: optimal_flight_level
      maximum_flight_level: 340
    descent_parts:
      - phase: descent
  diversion:
    range: distance
    climb_parts:
      - phase: diversion_climb
    cruise_part:
      segment: breguet
      engine_setting: cruise
      polar: data:aerodynamics:aircraft:cruise
    descent_parts:
      - phase: descent

Mission section

This is the main section. It allows to define one or several missions, that will be computed by the mission module.

A mission is identified by its name and has only the parts attribute that lists the phase and/or route names that compose the mission, with optionally a last item that is the reserve (see below).

The mission name is used when configuring the mission module in the FAST-OAD configuration file. If there is only one mission defined in the file, naming it in the configuration file is optional.

About mission start:

• Each mission begins by default by taxi-out and takeoff phases, but these phases are not defined in the mission file. One reason for that is that the mass input for the mission is the TakeOff Weight, which is the aircraft weight at the end of takeoff phase.

• A taxi-out phase is automatically computed at begin of the mission. To ignore this phase, simply put its duration to 0. in the input data file.

• The takeoff data are simple inputs of the mission model. They have to be computed in a dedicated takeoff model (available soon), or provided in the input data file.

About reserve:

The reserve keyword is typically designed to define fuel reserve as stated in EU-OPS 1.255.

It defines the amount of fuel that is expected to be still in tanks once the mission is complete. It takes as reference one of the route that composes the mission (ref attribute). The reserve is defined as the amount of fuel consumed during the referenced route, multiplied by the coefficient provided as the multiplier attribute.

Example:

missions:
  sizing:
    parts:
      - route: main_route
      - route: diversion
      - phase: holding
      - phase: landing
      - phase: taxi_in
      - reserve:
          ref: main_route
          multiplier: 0.03
  operational:
    parts:
      - route: main_route
      - phase: landing
      - phase: taxi_in