Aerospace Blockset™

ISA Atmosphere Model - Implement International Standard Atmosphere (ISA)

Library

Environment/Atmosphere

Description

The ISA Atmosphere Model block implements the mathematical representation of the international standard atmosphere values for ambient temperature, pressure, density, and speed of sound for the input geopotential altitude.

The ISA Atmosphere Model block icon displays the input and output metric units.

Dialog Box

Change atmospheric parameters: Select to customize various atmospheric parameters to be different from the ISA values.

Inputs and Outputs

Input	Dimension Type	Description
First		Contains the geopotential height.

Output	Dimension Type	Description
First		Contains the temperature.
Second		Contains the speed of sound.
Third		Contains the air pressure.
Fourth		Contains the air density.

Assumptions and Limitations

Below the geopotential altitude of 0 km and above the geopotential altitude of 20 km, temperature and pressure values are held. Density and speed of sound are calculated using a perfect gas relationship.

Reference

[1] U.S. Standard Atmosphere, 1976, U.S. Government Printing Office, Washington, D.C.