def compute_from(self, start: FlightPoint) -> pd.DataFrame:
self.complete_flight_point(
start) # needed to ensure all speed values are computed.
if self.target.altitude:
if isinstance(self.target.altitude, str):
# Target altitude will be modified along the process, so we keep track
# of the original order in target CL, that is not used otherwise.
self.target.CL = self.target.altitude # pylint: disable=invalid-name
# let's put a numerical, negative value in self.target.altitude to
# ensure there will be no problem in self._get_distance_to_target()
self.target.altitude = -1000.0
self.interrupt_if_getting_further_from_target = False
else:
# Target altitude is fixed, back to original settings (in case
# this instance is used more than once)
self.target.CL = None
self.interrupt_if_getting_further_from_target = True
atm = AtmosphereSI(start.altitude)
if self.target.equivalent_airspeed == self.CONSTANT_VALUE:
start.true_airspeed = atm.get_true_airspeed(
start.equivalent_airspeed)
elif self.target.mach == self.CONSTANT_VALUE:
start.true_airspeed = start.mach * atm.speed_of_sound
return super().compute_from(start)
def _get_distance_to_target(self,
flight_points: List[FlightPoint]) -> float:
current = flight_points[-1]
# Max flight level is first priority
max_authorized_altitude = self.maximum_flight_level * 100.0 * foot
if current.altitude >= max_authorized_altitude:
return max_authorized_altitude - current.altitude
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 self.CONSTANT_VALUE for one
# parameter. Let's get the real value from start point.
target_speed = copy(self.target)
for speed_param in [
"true_airspeed", "equivalent_airspeed", "mach"
]:
if isinstance(getattr(target_speed, speed_param), str):
setattr(target_speed, speed_param,
getattr(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
# Now we compute optimal altitude
optimal_altitude = self._get_optimal_altitude(
current.mass, target_speed.mach, current.altitude)
if self.target.CL == self.OPTIMAL_ALTITUDE:
self.target.altitude = optimal_altitude
else: # self.target.CL == self.OPTIMAL_FLIGHT_LEVEL:
self.target.altitude = get_closest_flight_level(
optimal_altitude, up_direction=False)
if self.target.altitude is not None:
return self.target.altitude - current.altitude
if self.target.true_airspeed and self.target.true_airspeed != self.CONSTANT_VALUE:
return self.target.true_airspeed - current.true_airspeed
if (self.target.equivalent_airspeed
and self.target.equivalent_airspeed != self.CONSTANT_VALUE):
return self.target.equivalent_airspeed - current.equivalent_airspeed
if self.target.mach is not None and self.target.mach != self.CONSTANT_VALUE:
return self.target.mach - current.mach
raise FastFlightSegmentIncompleteFlightPoint(
"No valid target definition for altitude change.")
def distance_to_optimum(altitude):
atm = AtmosphereSI(altitude)
true_airspeed = mach * atm.speed_of_sound
optimal_air_density = (
2.0 * mass * g / (self.reference_area * true_airspeed ** 2 * self.polar.optimal_cl)
)
return (atm.density - optimal_air_density) * 100.0
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(self,
inputs,
outputs,
discrete_inputs=None,
discrete_outputs=None):
atmosphere = AtmosphereSI(
inputs["data:mission:sizing:main_route:cruise:altitude"])
cruise_speed = atmosphere.speed_of_sound * inputs[
"data:TLAR:cruise_mach"]
cruise_distance = inputs[
"data:mission:sizing:main_route:cruise:distance"]
ld_ratio = inputs["data:aerodynamics:aircraft:cruise:L_D_max"]
sfc = inputs["data:propulsion:SFC"]
range_factor = cruise_speed * ld_ratio / g / sfc
# During first iterations, SFC will be incorrect and range_factor may be too low,
# resulting in null or too small cruise_mass_ratio.
# Forcing cruise_mass_ratio to a minimum of 0.3 avoids problems and should not
# harm (no airplane loses 70% of its weight from fuel consumption)
cruise_mass_ratio = np.maximum(
0.3, 1.0 / np.exp(cruise_distance / range_factor))
outputs[
"data:mission:sizing:main_route:cruise:mass_ratio"] = cruise_mass_ratio
def compute_from(self, start: FlightPoint) -> pd.DataFrame:
start = FlightPoint(start)
self.complete_flight_point(start) # needed to ensure all speed values are computed.
if self.target.altitude and self.target.altitude < 0.0:
# Target altitude will be modified along the process, so we keep track
# of the original order in target CL, that is not used otherwise.
self.target.CL = self.target.altitude
self.interrupt_if_getting_further_from_target = False
atm = AtmosphereSI(start.altitude)
if self.target.equivalent_airspeed == "constant":
start.true_airspeed = atm.get_true_airspeed(start.equivalent_airspeed)
elif self.target.mach == "constant":
start.true_airspeed = start.mach * atm.speed_of_sound
return super().compute_from(start)
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)
def compute(self, inputs, outputs):
if self.low_speed_aero:
mach = inputs["data:aerodynamics:aircraft:takeoff:mach"]
altitude = 0.0
else:
mach = inputs["data:TLAR:cruise_mach"]
altitude = inputs["data:mission:sizing:main_route:cruise:altitude"]
reynolds = AtmosphereSI(altitude).get_unitary_reynolds(mach)
if self.low_speed_aero:
outputs["data:aerodynamics:wing:low_speed:reynolds"] = reynolds
else:
outputs["data:aerodynamics:wing:cruise:reynolds"] = reynolds
def compute(self,
inputs,
outputs,
discrete_inputs=None,
discrete_outputs=None):
F = inputs["data:propeller:force:hover:z"]
D = inputs["data:propeller:diameter"]
Ct = inputs["data:propeller:Ct"]
altitude = inputs["settings:altitude"]
atm = AtmosphereSI(altitude)
rho = atm.density
n = np.sqrt(F / (Ct * rho * D**4.0))
omega = n * 2.0 * pi
outputs["data:propeller:frequency:hover"] = n
outputs["data:propeller:speed:hover"] = omega
def compute(self,
inputs,
outputs,
discrete_inputs=None,
discrete_outputs=None):
F_pro = inputs["data:propeller:force:takeoff:z"]
Ct = inputs["data:propeller:Ct"]
altitude = inputs["settings:altitude"]
k_ND = inputs["data:propeller:ND:k"]
ND_max = inputs["data:propeller:ND:max"]
atm = AtmosphereSI(altitude)
rho = atm.density
ND = ND_max / k_ND
D_pro = (F_pro / (Ct * rho * ND**2.0))**0.5
outputs["data:propeller:ND"] = ND
outputs["data:propeller:diameter"] = D_pro
def compute(self,
inputs,
outputs,
discrete_inputs=None,
discrete_outputs=None):
D = inputs["data:propeller:diameter"]
n = inputs["data:propeller:frequency:hover"]
omega = inputs["data:propeller:speed:hover"]
Cp = inputs["data:propeller:Cp"]
altitude = inputs["settings:altitude"]
atm = AtmosphereSI(altitude)
rho = atm.density
P = Cp * rho * n**3.0 * D**5.0
T = P / omega
outputs["data:propeller:power:hover"] = P
outputs["data:propeller:torque:hover"] = T
def compute_cruise_mass_ratio(self, initial_cruise_mass, cruise_distance):
"""
:param initial_cruise_mass:
:param cruise_distance:
:return: (mass at end of cruise) / (mass at start of cruise)
"""
self.thrust = initial_cruise_mass / self.lift_drag_ratio * g
flight_point = FlightPoint(
mach=self.cruise_mach,
altitude=self.cruise_altitude,
engine_setting=EngineSetting.CRUISE,
thrust=self.thrust,
)
self.propulsion.compute_flight_points(flight_point)
self.sfc = flight_point.sfc
self.thrust_rate = flight_point.thrust_rate
atmosphere = AtmosphereSI(self.cruise_altitude)
cruise_speed = atmosphere.speed_of_sound * self.cruise_mach
range_factor = cruise_speed * self.lift_drag_ratio / g / self.sfc
return 1.0 / np.exp(cruise_distance / range_factor)
# Copyright (C) 2020 ONERA & ISAE-SUPAERO # FAST is free software: you can redistribute it and/or modify # it under the terms of the GNU General Public License as published by # the Free Software Foundation, either version 3 of the License, or # (at your option) any later version. # This program is distributed in the hope that it will be useful, # but WITHOUT ANY WARRANTY; without even the implied warranty of # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the # GNU General Public License for more details. # You should have received a copy of the GNU General Public License # along with this program. If not, see <https://www.gnu.org/licenses/>. from fastoad.utils.physics import AtmosphereSI # Atmosphere at limits of troposhere ATM_SEA_LEVEL = AtmosphereSI(0) ATM_TROPOPAUSE = AtmosphereSI(11000) # Constants for computation of maximum thrust --------------------------------- # (see E. Roux model definition in roux:2005) A_MS = -2.74e-4 A_FM = 2.67e-4 B_MS = 1.91e-2 B_FM = -2.35e-2 C_MS = 1.21e-3 C_FM = -1.32e-3 D_MS = -8.48e-4 D_FM = 3.14e-4 E_MS = 8.96e-1 E_FM = 5.22e-1
