Compute airspeed (true/calibrated/equivalent/Mach), atmospheric data, and other flight condition quantities, with easy unit conversion.
Project description
About
Airspeed conversions (true/calibrated/equivalent/Mach), atmospheric data, and more with built-in unit checking. Specific sub-modules include:
flightcondition
: input altitude to compute common flight condition data. Easily swap between Mach number, true airspeed, calibrated airspeed, and equivalent airspeed. Includes atmospheric data.atmosphere
: input altitude to compute 1993 International Standard Atmosphere data. Many relevant, derived quantities are included.units
: built-in unit-checking and conversion using pint package.
See examples below for usage!
Installation
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
Usage
Import all utilities with,
from flightcondition import *
or more explicitly as shown in the following examples.
Flight Condition
The Flightcondition
class can be used to compute and interact with
common flight condition data. Access flight condition quantities through
altitude
, speed
, and length
objects.
Outputs include:
atm
atmospheric quantities - seeAtmosphere
class below.vel
airspeed quantities: Mach numberM
, true airspeedTAS
, calibrated airspeedCAS
, equivalent airspeedEAS
, dynamic pressureq_inf
, and Reynolds number per unit lengthRe_by_L
.len
length-scale quantities: Reynolds numberRe
.
Quantities may also be accessed using their full name with the byname
object. For example, Mach number can be accessed using vel.M
or by its
full name using byname.mach_number
Usage:
from flightcondition import FlightCondition, unit, dimless
# Compute flight condition at 3 km, Mach 0.5
fc = FlightCondition(3*unit('km'), M=0.5)
# Uncomment to print summary of flight condition quantities:
#print(f"{fc}")
# Uncomment to print abbreviated output in US units:
#print(f"\n{fc.tostring(full_output=False, US_units=True)}")
# Access true, calibrated, equivalent airspeeds
KTAS = fc.vel.TAS.to('knots')
KCAS = fc.vel.CAS.to('knots')
KEAS = fc.vel.EAS.to('knots')
print(f"Flying at {KTAS.magnitude:.4g} KTAS,"
f" which is {KCAS.magnitude:.4g} KCAS,"
f" or {KEAS.magnitude:.4g} KEAS")
# >>> Flying at 319.4 KTAS, which is 277.7 KCAS, or 275.1 KEAS
# Access atmospheric data (see Atmosphere class for more)
atm = fc.atm # access Atmosphere object
h, p, T, rho, nu, a = atm.h, atm.p, atm.T, atm.rho, atm.nu, atm.a
print(f"The ambient temperature at {h.to('km'):.4g} is {T:.4g}")
# >>> The ambient temperature at 3 km is 268.7 K
# Compute again instead using true airspeed and altitude in km
fc = FlightCondition(3.048*unit('km'), TAS=401.7*unit('mph'))
#print(f"{fc}") # uncomment to print output
# Compute for a range of altitudes at 275.14 knots-equivalent
# airspeed with a characteristic length scale of 10 meters
fc = FlightCondition([0, 9.8425, 20]*unit('kft'),
EAS=275.14*unit('kt'),
L=10*unit('m'))
# Compute additional derived quantities
# Explore the class data structure for all options
print(f"\nThe dynamic pressure in psi is "
f"{fc.vel.q_inf.to('psi'):.3g}")
# >>> The dynamic pressure in psi is [1.78 1.78 1.78] psi
print(f"The Reynolds number is {fc.len.Re:.3g}")
# >>> The Reynolds number is [9.69e+07 8.82e+07 7.95e+07]
# Alternatively access quantities by their full name
print(fc.vel.TAS == fc.byname.true_airspeed)
# >>> [ True True True]
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
MFP
Usage:
from flightcondition import Atmosphere, unit
# Compute atmospheric data for a scalar or array of altitudes
h = [0.0, 44.2, 81.0] * unit('km')
atm = Atmosphere(h)
# Uncomment to print all atmospheric quantities:
#print(f"\n{atm}")
# Uncomment to print while specifying abbreviated output in US units:
#print(f"\n{atm.tostring(full_output=False, US_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, k = atm.p, atm.T, atm.rho, atm.nu, atm.a, atm.k
print(f"\nThe pressure in psi is {p.to('psi'):.3g}")
# >>> The pressure in psi is [14.7 0.024 0.000129] psi
# Compute additional properties such as mean free path
# Explore the class data structure for all options
print( f"\nThe mean free path = {atm.MFP:.3g}")
# >>> The mean free path = [7.25e-08 4.04e-05 0.00564] yd
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
.
Command Line Interface
It is also possible to compute flight conditions from the command line for
convenience but with limited functionality. Run flightcondition -h
for
help.
An example call is provided for the flight condition of 233 knots-equivalent-airspeed at 23 kilo-feet with a length scale of 4 feet:
flightcondition --alt 23 kft --EAS 233 kt --len 4 ft
License
flightcondition
is licensed under the MIT LICENSE. See the LICENSE document.
Disclaimer
The software is provided “as is”, without warranty of any kind, express or implied, including but not limited to the warranties of merchantability, fitness for a particular purpose and noninfringement. In no event shall the authors or copyright holders be liable for any claim, damages or other liability, whether in an action of contract, tort or otherwise, arising from, out of or in connection with the software or the use or other dealings in the software.
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