flightcondition 22.3

Install Commands

Install using the pip package-management system. The easiest method is to open the terminal and run:

pip install flightcondition

Alternatively, manually download the source code, unpack, and run:

pip install <path/to/flightcondition>

Dependencies

• numpy: package for scientific computing.

• pint: package for dealing with units.

Flight Condition

The Flightcondition class can be used to compute and interact with common flight condition data.

Outputs include:

• Mach number mach

• True airspeed TAS

• Calibrated airspeed CAS

• Equivalent airspeed EAS

• Dynamic pressure q_inf

• Reynolds number reynolds_number(ell)

• Reynolds number per-unit-length reynolds_number_per_unit_length(length_unit)

• Atmosphere data atm (see atmosphere below)

Usage:

from flightcondition import FlightCondition, unit, dimless

# Compute flight conditions for a scalar or array of altitudes
altitudes = [0, 10e3, 33.5e3] * unit('ft')
fc = FlightCondition(altitudes, EAS=300*unit('knots'))

# Print flight condition data:
print(f"{fc}")

# Print extended output in Imperial units:
print(f"\n{fc.tostring(full_output=True, imperial_units=True)}")

# Access flight speed formats individually
M_inf, U_inf, U_CAS, U_EAS = fc.mach, fc.TAS, fc.CAS, fc.EAS

# Access atmospheric data alone (see Atmosphere class for options)
atm = fc.atm  # access Atmosphere object 'atm'
p, T, rho, nu, a = atm.p, atm.T, atm.rho, atm.nu, atm.a

# Input true/calibrated/equivalent airspeed or Mach number
fc_TAS = FlightCondition(altitudes, TAS=300*unit('knots'))
fc_CAS = FlightCondition(altitudes, CAS=300*unit('knots'))
fc_EAS = FlightCondition(altitudes, EAS=300*unit('knots'))
fc_mach = FlightCondition(altitudes, mach=0.4535*dimless)

# Specify desired units on input and output
altitudes_in_km = [0, 3.048, 10.2108] * unit('km')
fc_other_units = FlightCondition(altitudes, EAS=154.33*unit('m/s'))
U_TAS = fc_other_units.TAS
print(f"\nThe true airspeed in m/s is {U_TAS.to('m/s'):.5g}")
print(f"The true airspeed in km/s is {U_TAS.to('km/s'):.5g}")

# Compute additional derived quantities (see class for all options)
print(f"\nThe dynamic pressure in psi is {fc.q_inf.to('psi'):.5g}")
ell = 60 * unit('in')  # arbitrary length scale of interest
print(f"The Reynolds number is {fc.reynolds_number(ell):.5g}")
print(f"The Reynolds number per-unit-length [1/in] is "
    f"{fc.reynolds_number_per_unit_length('in'):.5g}")

Atmosphere

The Atmosphere class can be used to compute and interact with common standard atmosphere data and derived quantities.

Outputs include:

• Pressure p

• Temperature T

• Density rho

• Sound speed a

• Dynamic viscosity mu

• Kinematic viscosity nu

• Thermal conductivity k

• Layer name layer.name

• Geometric altitude h

• Geopotential altitude H

• Acceleration due to gravity g

• Mean free path mean_free_path

Usage:

from flightcondition import Atmosphere, unit

# Compute atmospheric data for a scalar or array of altitudes
h = [0.0, 12.7, 44.2, 81.0] * unit('km')
atm = Atmosphere(h)

# Print abbreviated output:
print(f"\n{atm}")

# Print extended output in Imperial units:
print(f"\n{atm.tostring(full_output=True, imperial_units=True)}")

# See also the linspace() function from numpy, e.g.
# h = linspace(0, 81.0, 82) * unit('km')

# Access individual properties and convert to desired units: "
p, T, rho, nu, a = atm.p, atm.T, atm.rho, atm.nu, atm.a
print(f"\nThe pressure in psi is {p.to('psi'):.5g}")

# Compute additional properties such as thermal conductivity,
# mean free path, and more (see class for all options)
print(f"\nThe thermal conductivity is {atm.k:.5g}"
    f"\nThe mean free path = {atm.mean_free_path:.5g}")

Units

Conveniently input, output, and convert units using pint units.

from flightcondition import unit, printv

h = 33 * unit('km')
print(h.to('kft'))
# >>> 108.26771653543307 kft
printv(h, to='kft')
# >>> h = 108.27 kft

U_inf = 20 * unit('knots')
rho_inf = 1.225 * unit('kg/m^3')
q_inf = 0.5*rho_inf*U_inf**2
printv(q_inf, to='psi')
# >>> q_inf = 0.0094042 psi

Note that pint does not support conflicting unit registries so avoid interactions between flightcondition.unit and a separate pint.UnitRegistry.