def complete_flight_point(self, 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).
:param flight_point: the flight point that will be completed in-place
"""
flight_point.engine_setting = self.engine_setting
self._complete_speed_values(flight_point)
# Mach number is capped by self.maximum_mach
if flight_point.mach > self.maximum_mach:
flight_point.mach = self.maximum_mach
flight_point.true_airspeed = flight_point.equivalent_airspeed = None
self._complete_speed_values(flight_point)
atm = AtmosphereSI(flight_point.altitude)
reference_force = 0.5 * atm.density * flight_point.true_airspeed ** 2 * self.reference_area
if self.polar:
flight_point.CL = flight_point.mass * g / reference_force
flight_point.CD = self.polar.cd(flight_point.CL)
else:
flight_point.CL = flight_point.CD = 0.0
flight_point.drag = flight_point.CD * reference_force
self._compute_propulsion(flight_point)
flight_point.slope_angle, flight_point.acceleration = self._get_gamma_and_acceleration(
flight_point.mass, flight_point.drag, flight_point.thrust
)
def compute_next_flight_point(
self, flight_points: List[FlightPoint], time_step: float
) -> FlightPoint:
"""
Computes time, altitude, speed, mass and ground distance of next flight point.
:param flight_points: previous flight points
:param time_step: time step for computing next point
:return: the computed next flight point
"""
start = flight_points[0]
previous = flight_points[-1]
next_point = FlightPoint()
next_point.mass = previous.mass - self.propulsion.get_consumed_mass(previous, time_step)
next_point.time = previous.time + time_step
next_point.ground_distance = (
previous.ground_distance
+ previous.true_airspeed * time_step * np.cos(previous.slope_angle)
)
self._compute_next_altitude(next_point, previous)
if self.target.true_airspeed == "constant":
next_point.true_airspeed = previous.true_airspeed
elif self.target.equivalent_airspeed == "constant":
next_point.equivalent_airspeed = start.equivalent_airspeed
elif self.target.mach == "constant":
next_point.mach = start.mach
else:
next_point.true_airspeed = previous.true_airspeed + time_step * previous.acceleration
# The naming is not done in complete_flight_point for not naming the start point
next_point.name = self.name
return next_point
def _get_distance_to_target(self, flight_points: List[FlightPoint]) -> bool:
current = flight_points[-1]
if self.target.CL:
# Optimal altitude is based on a target Mach number, though target speed
# may be specified as TAS or EAS. If so, Mach number has to be computed
# for target altitude and speed.
# First, as target speed is expected to be set to "constant" for one
# parameter. Let's get the real value from start point.
target_speed = FlightPoint(self.target)
for speed_param in ["true_airspeed", "equivalent_airspeed", "mach"]:
if isinstance(target_speed.get(speed_param), str):
target_speed[speed_param] = flight_points[0][speed_param]
# Now, let's compute target Mach number
atm = AtmosphereSI(max(self.target.altitude, current.altitude))
if target_speed.equivalent_airspeed:
target_speed.true_airspeed = atm.get_true_airspeed(target_speed.equivalent_airspeed)
if target_speed.true_airspeed:
target_speed.mach = target_speed.true_airspeed / atm.speed_of_sound
# Mach number has to be capped by self.maximum_mach
target_mach = min(target_speed.mach, self.maximum_mach)
# Now we compute optimal altitude
optimal_altitude = self._get_optimal_altitude(
current.mass, target_mach, current.altitude
)
if self.target.CL == self.OPTIMAL_ALTITUDE:
self.target.altitude = optimal_altitude
else: # self.target.CL == self.OPTIMAL_FLIGHT_LEVEL:
flight_level = 1000 * foot
self.target.altitude = flight_level * np.floor(optimal_altitude / flight_level)
if self.target.altitude:
return self.target.altitude - current.altitude
elif self.target.true_airspeed:
return self.target.true_airspeed - current.true_airspeed
elif self.target.equivalent_airspeed:
return self.target.equivalent_airspeed - current.equivalent_airspeed
elif self.target.mach:
return self.target.mach - current.mach
def _complete_speed_values(flight_point: FlightPoint):
"""
Computes consistent values between TAS, EAS and Mach, assuming one of them is defined.
"""
atm = AtmosphereSI(flight_point.altitude)
if flight_point.true_airspeed is None:
if flight_point.mach is not None:
flight_point.true_airspeed = flight_point.mach * atm.speed_of_sound
elif flight_point.equivalent_airspeed is not None:
flight_point.true_airspeed = atm.get_true_airspeed(
flight_point.equivalent_airspeed)
else:
raise FastFlightSegmentIncompleteFlightPoint(
"Flight point should be defined for true_airspeed, "
"equivalent_airspeed, or mach.")
if flight_point.mach is None:
flight_point.mach = flight_point.true_airspeed / atm.speed_of_sound
if flight_point.equivalent_airspeed is None:
flight_point.equivalent_airspeed = atm.get_equivalent_airspeed(
flight_point.true_airspeed)
