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 86km.
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.
•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, with other choice as optional output.
Examples included in help:
•Create tables of atmospheric properties up to 30000ft for a cold (-15degC), standard, and hot (+15degC) 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 the SI dynamic pressure, Mach number, Reynolds number, and stagnation temperature of an aircraft flying at flight level FL500 (50000ft) with speed 250m/s and characteristic length of 2m.
•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.
References: ESDU 77022; www.pdas.com/atmos.html |
