fastoad.models.performances.mission.segments.registered.altitude_change module

Classes for climb/descent segments.

class fastoad.models.performances.mission.segments.registered.altitude_change.AltitudeChangeSegment(name: str = '', target: ~fastoad.model_base.flight_point.FlightPoint = <object object>, isa_offset: float = 0.0, propulsion: ~fastoad.model_base.propulsion.IPropulsion = <object object>, polar: ~fastoad.models.performances.mission.polar.Polar = <object object>, polar_modifier: ~fastoad.models.performances.mission.polar_modifier.AbstractPolarModifier = <factory>, reference_area: float = <object object>, time_step: float = 2.0, maximum_CL: float = None, altitude_bounds: tuple = (-500.0, 40000.0), mach_bounds: tuple = (-1e-06, 5.0), interrupt_if_getting_further_from_target: bool = True, engine_setting: ~fastoad.constants.EngineSetting = EngineSetting.CLIMB, load_factor: float = 1.0, thrust_rate: float = 1.0, maximum_flight_level: float = 500.0)[source]

Bases: AbstractManualThrustSegment, AbstractLiftFromWeightSegment

Computes a flight path segment where altitude is modified with constant speed.

Note

Setting speed

Constant speed may be:

  • constant true airspeed (TAS)

  • constant equivalent airspeed (EAS)

  • constant Mach number

Target should have "constant" as definition for one parameter among true_airspeed, equivalent_airspeed or mach. All computed flight points will use the corresponding start value. The two other speed values will be computed accordingly.

If not “constant” parameter is set, constant TAS is assumed.

Note

Setting target

Target can be an altitude, or a speed:

  • Target altitude can be a float value (in meters), or can be set to:

    • OPTIMAL_ALTITUDE: in that case, the target altitude will be the altitude where maximum lift/drag ratio is achieved for target speed, depending on current mass.

    • OPTIMAL_FLIGHT_LEVEL: same as above, except that altitude will be rounded to the nearest flight level (multiple of 100 feet).

  • For a speed target, as explained above, one value TAS, EAS or Mach must be "constant". One of the two other ones can be set as target.

In any case, the achieved value will be capped so it respects maximum_flight_level.

time_step: float = 2.0

Used time step for computation (actual time step can be lower at some particular times of the flight path).

maximum_flight_level: float = 500.0

The maximum allowed flight level (i.e. multiple of 100 feet).

OPTIMAL_ALTITUDE = 'optimal_altitude'

Using this value will tell to target the altitude with max lift/drag ratio.

OPTIMAL_FLIGHT_LEVEL = 'optimal_flight_level'

Using this value will tell to target the nearest flight level to altitude with max lift/drag ratio.

compute_from_start_to_target(start: FlightPoint, target: FlightPoint) → DataFrame[source]

Here should come the implementation for computing flight points between start and target flight points.

Parameters:

  • start –

  • target – Definition of segment target

Returns:

a pandas DataFrame where column names match fields of FlightPoint

get_distance_to_target(flight_points: List[FlightPoint], target: FlightPoint) → float[source]

Computes a “distance” from last flight point to target.

Computed does not need to have a real meaning. The important point is that it must be signed so that algorithm knows on which “side” of the target we are. And of course, it should be 0. if flight point is on target.

Parameters:

  • flight_points – list of all currently computed flight_points

  • target – segment target (will not contain relative values)

Returns:

  1. if target is attained, a non-null value otherwise

get_gamma_and_acceleration(flight_point: FlightPoint) → Tuple[float, float][source]

Computes slope angle (gamma) and acceleration.

Parameters:

flight_point – parameters after propulsion model has been called (i.e. mass, thrust and drag are available)

Returns:

slope angle in radians and acceleration in m**2/s

CONSTANT_VALUE = 'constant'

Using this value will tell to keep the associated parameter constant.

altitude_bounds: tuple = (-500.0, 40000.0)

Minimum and maximum authorized altitude values. If computed altitude gets beyond these limits, computation will be interrupted and a warning message will be issued in logger.

complete_flight_point(flight_point: FlightPoint)

Computes data for provided flight point.

Assumes that it is already defined for time, altitude, mass, ground distance and speed (TAS, EAS, or Mach).

Parameters:

flight_point – the flight point that will be completed in-place

static complete_flight_point_from(flight_point: FlightPoint, source: FlightPoint)

Sets undefined values in flight_point using the ones from source.

The particular case of speeds is taken into account: if at least one speed parameter is defined, all other speed parameters are considered defined, because they will be deduced when needed.

Parameters:

  • flight_point –

  • source –

compute_from(start: FlightPoint) → DataFrame

Computes the flight path segment from provided start point.

Computation ends when target is attained, or if the computation stops getting closer to target. For instance, a climb computation with too low thrust will only return one flight point, that is the provided start point.

Important

When subclasssing, if you need to overload compute_from(), you should consider overriding compute_from_start_to_target() instead. Therefore, you will take benefit of the preprocessing of start and target flight points that is done in compute_from().

Parameters:

start – the initial flight point, defined for altitude, mass and speed (true_airspeed, equivalent_airspeed or mach). Can also be defined for time and/or ground_distance.

Returns:

a pandas DataFrame where column names match fields of FlightPoint

compute_lift(flight_point: FlightPoint, reference_force: float, polar: Polar)

Fills values for CL, and lift in provided flight_point.

Parameters:

  • flight_point –

  • reference_force – CL = lift / reference_force

  • polar – unused here, but can be used when overloading this method

compute_next_flight_point(flight_points: List[FlightPoint], time_step: float) → FlightPoint

Computes time, altitude, speed, mass and ground distance of next flight point.

Parameters:

  • flight_points – previous flight points

  • time_step – time step for computing next point

Returns:

the computed next flight point

compute_propulsion(flight_point: FlightPoint)

Computes propulsion data.

Provided flight point is modified in place.

Generally, this method should end with:

self.propulsion.compute_flight_points(flight_point)
Parameters:

flight_point –

static consume_fuel(flight_point: FlightPoint, previous: FlightPoint, fuel_consumption: float = None, mass_ratio: float = None)

This method should be used whenever fuel consumption has to be stored.

It ensures that “mass” and “consumed_fuel” fields will be kept consistent.

Mass can be modified using the ‘fuel_consumption” argument, or the ‘mass_ratio’ argument. One of them should be provided.

Parameters:

  • flight_point – the FlightPoint instance where “mass” and “consumed_fuel” fields will get new values

  • previous – FlightPoint instance that will be the base for the computation

  • fuel_consumption – consumed fuel, in kg, between ‘previous’ and ‘flight_point’. Positive when fuel is consumed.

  • mass_ratio – the ratio flight_point.mass/previous.mass

engine_setting: EngineSetting = 2

The EngineSetting value associated to the segment. Can be used in the propulsion model.

get_next_alpha(previous_point: FlightPoint, time_step: float) → float

Determine the next angle of attack.

Parameters:

  • previous_point – the flight point from which next alpha is computed

  • time_step – the duration between computed flight point and previous_point

interrupt_if_getting_further_from_target: bool = True

If True, computation will be interrupted if a parameter stops getting closer to target between two iterations (which can mean the provided thrust rate is not adapted).

isa_offset: float = 0.0

The temperature offset for ISA atmosphere model.

load_factor: float = 1.0

Lift is computed so it is equal to load_factor * weight

mach_bounds: tuple = (-1e-06, 5.0)

Minimum and maximum authorized mach values. If computed Mach gets beyond these limits, computation will be interrupted and a warning message will be issued in logger.

maximum_CL: float = None
name: str = ''
polar: Polar = <object object>

The Polar instance that will provide drag data.

propulsion: IPropulsion = <object object>

A IPropulsion instance that will be called at each time step.

reference_area: float = <object object>

The reference area, in m**2.

property target: FlightPoint

The base class of the class hierarchy.

When called, it accepts no arguments and returns a new featureless instance that has no instance attributes and cannot be given any.

thrust_rate: float = 1.0
polar_modifier: AbstractPolarModifier