Documentation Center

  • Trial Software
  • Product Updates

COESA Atmosphere Model

Implement 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 32,000 meters (approximately 104,987 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 list.

Dialog Box

Units

Specifies the input and output units:

Units

Height

Temperature

Speed of Sound

Air Pressure

Air Density

Metric (MKS)

Meters

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

InputDimension TypeDescription
First Contains the geopotential height.

OutputDimension TypeDescription
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 m (0 feet) and above the geopotential altitude of 84,852 m (approximately 278,386 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_calibratedaeroblk_calibrated model, the aeroblk_indicatedaeroblk_indicated model, and the airframe in aeroblk_HL20aeroblk_HL20 for examples of this block.

Reference

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

Was this topic helpful?