Aerospace Blockset

COESA Atmosphere Model

Implement the 1976 COESA lower atmosphere

Library

Environment/Atmosphere

Description

The COESA Atmosphere Model block implements the mathematical representation of the 1976 Committee on Extension to the Standard Atmosphere (COESA) United States standard lower atmospheric values for absolute temperature, pressure, density, and speed of sound for the input geopotential altitude.

Below 32000 meters (approximately 104987 feet), the U.S. Standard Atmosphere is identical with the Standard Atmosphere of the International Civil Aviation Organization (ICAO).

The COESA Atmosphere Model block icon displays the input and output units selected from the Units pop-up menu.

Dialog Box

Units

Specifies the input and output units:

	Height	Temperature	Speed of Sound	Air Pressure	Air Density
Metric (MKS)	Meters	Degrees Kelvin	Meters per second	Pascal	Kilograms per cubic meter
English (Velocity in ft/s)	Feet	Degrees Rankine	Feet per second	Pound-force per square inch	Slug per cubic foot
English (Velocity in kts)	Feet	Degrees Rankine	Knots	Pound-force per square inch	Slug per cubic foot

Specification

Specify the atmosphere model type from one of the following atmosphere models. The default is 1976 COESA-extended U.S. Standard Atmosphere.

MIL-HDBK-310 This selection is linked to the Non-Standard Day 310 block. See the block reference for more information.

MIL-STD-210C This selection is linked to the Non-Standard Day 210C block. See the block reference for more information.

Action for out of range input

Specify if out of range input invokes a warning, error, or no action.

Inputs and Outputs

The input is geopotential height.

The four outputs are temperature, speed of sound, air pressure, and air density.

Assumptions and Limitations

Below the geopotential altitude of 0 m (0 feet) and above the geopotential altitude of 84852 m (approximately 278386 feet), temperature values are extrapolated linearly and pressure values are extrapolated logarithmically. Density and speed of sound are calculated using a perfect gas relationship.

Examples

See the aeroblk_calibrated model, the aeroblk_indicated model, and Airframe in the aeroblk_HL20 demo for examples of this block.

References

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

See Also

ISA Atmosphere Model

Non-Standard Day 210C

Non-Standard Day 310

Calculate Range

Create 3x3 Matrix