A standard atmosphere function based on the 1976 Standard Atmosphere returns density, speed of sound, temperature, pressure, and viscosity for a given altitude input up to 86 km.
This function is designed to be useful for those designing and analyzing aircraft and has the following features that hitherto have not been combined in a single standard atmosphere function:
•Input may be a scalar, vector, matrix, or n-dimensional array of altitudes. The function is vectorized and fast for computing atmospheric conditions at a large number of points simultaneously.
•Temperature offset option for non-standard atmospheres, e.g analyzing hot day aircraft performance.
•Input and output may independently be either SI or imperial units.
•Units consistency can be enforced by using the DimensionedVariable class, reducing errors and making code clearer.
•Returns everything needed to easily determine important parameters such as dynamic pressure, Mach number, Reynolds number, stagnation temperature, etc.
•Option for geometric instead of geopotential altitude input.
Examples included in help:
•Create tables of atmospheric properties up to 30000 ft for a cold (-15°C), standard, and hot (+15°C) day with columns
[h(ft) Z(ft) rho(slug/ft3) sigma a(ft/s) T(°R) P(psf) µ(slug/ft-s) nu(ft2/s)]
using 3-dimensional array inputs.
•Find atmospheric properties at every 100m of geometric height for an off-standard atmosphere with temperature offset varying +/- 25 degC sinusoidally with a period of 4km.
•Use the capabilities of the DimensionedVariable class to find the SI dynamic pressure, Mach number, Reynolds number, and stagnation temperature of an aircraft flying at flight level FL500 (50000 ft) with speed 500 knots and characteristic length of 80 inches.
References: ESDU 77022; www.pdas.com/atmos.html