fastoad.utils.physics.atmosphere module

Simple implementation of International Standard Atmosphere.

class fastoad.utils.physics.atmosphere.Atmosphere(altitude: Union[float, Sequence[float]], delta_t: float = 0.0, altitude_in_feet: bool = True)

Bases: object

Simple implementation of International Standard Atmosphere for troposphere and stratosphere.

Atmosphere properties are provided in the same “shape” as provided altitude:

• if altitude is given as a float, returned values will be floats

• if altitude is given as a sequence (list, 1D numpy array, …), returned values will be 1D numpy arrays

• if altitude is given as nD numpy array, returned values will be nD numpy arrays

Usage:

>>> pressure = Atmosphere(30000).pressure # pressure at 30,000 feet, dISA = 0 K
>>> density = Atmosphere(5000, 10).density # density at 5,000 feet, dISA = 10 K


>>> atm = Atmosphere(np.arange(0,10001,1000, 15)) # init for alt. 0 to 10,000, dISA = 15K
>>> temperatures = atm.pressure # pressures for all defined altitudes
>>> viscosities = atm.kinematic_viscosity # viscosities for all defined altitudes

Parameters

• altitude – altitude (units decided by altitude_in_feet)

• delta_t – temperature increment (°C) applied to whole temperature profile

• altitude_in_feet – if True, altitude should be provided in feet. Otherwise, it should be provided in meters.

property delta_t

Temperature increment applied to whole temperature profile as provided at instantiation

property density

Density in kg/m3

get_altitude(altitude_in_feet: bool = True) → Union[float, Sequence[float]]

Parameters

altitude_in_feet – if True, altitude is returned in feet. Otherwise, it is returned in meters

Returns

altitude provided at instantiation

get_equivalent_airspeed(true_airspeed)

Computes equivalent airspeed (EAS) from true airspeed (TAS).

Parameters

true_airspeed – in m/s

Returns

equivalent airspeed in m/s

get_true_airspeed(equivalent_airspeed)

Computes true airspeed (TAS) from equivalent airspeed (EAS).

Parameters

equivalent_airspeed – in m/s

Returns

true airspeed in m/s

get_unitary_reynolds(mach)

Parameters

mach – Mach number

Returns

Unitary Reynolds number in 1/m

property kinematic_viscosity

Kinematic viscosity in m2/s

property pressure

Pressure in Pa

property speed_of_sound

Speed of sound in m/s

property temperature

Temperature in K

class fastoad.utils.physics.atmosphere.AtmosphereSI(altitude: Union[float, Sequence[float]], delta_t: float = 0.0)

Bases: fastoad.utils.physics.atmosphere.Atmosphere

Same as Atmosphere except that altitudes are always in meters.

Parameters

• altitude – altitude in meters

• delta_t – temperature increment (°C) applied to whole temperature profile

property altitude