COESA Atmosphere Model

Implement 1976 COESA lower atmosphere

  • Library:
  • Aerospace Blockset / 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.

The COESA Atmosphere Model, Non-Standard Day 210C, and Non-Standard Day 310 blocks are identical blocks. When configured for COESA Atmosphere Model, the block implements the COESA mathematical representation. When configured for Non-Standard Day 210C, the block implements MIL-STD-210C climatic data. When configured for Non-Standard Day 310, the block implements MIL-HDBK-310 climatic data.

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 port labels change based on the input and output units selected from the Units list.

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.

Ports

Input

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Geopotential height, specified as a scalar or array, in specified units.

Data Types: double

Output

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Temperature, specified as a scalar or array, in specified units.

Data Types: double

Speed of sound, specified as a scalar or array, in specified units.

Data Types: double

Air pressure, specified as a scalar or array, in specified units.

Data Types: double

Air density, specified as a scalar or array, in specified units.

Data Types: double

Parameters

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Input and output units, specified as:

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

Programmatic Use

Block Parameter: units
Type: character vector
Values: 'Metric (MKS)' | 'English (Velocity in ft/s)' | 'English (Velocity in kts)'
Default: 'Metric (MKS)'

Atmosphere model type, specified as 1976 COESA-extended U.S. Standard Atmosphere, MIL-HDBK-310, or MIL-STD-210C. For the MIL-HDBK-310 and MIL-STD-210C options:

MIL-HDBK-310

This selection is linked to the Non-Standard Day 310C block. See the block reference for more information. Selecting MIL-HDBK-310 enables the parameters Atmospheric model type, Extreme parameter, Frequency of occurrence, and Altitude of extreme value.

MIL-STD-210C

This selection is linked to the Non-Standard Day 210C block. See the block reference for more information. Selecting MIL-HDBK-310 enables the parameters Atmospheric model type, Extreme parameter, Frequency of occurrence, and Altitude of extreme value.

Dependencies

Selecting MIL-HDBK-310 or MIL-STD-210C enables these parameters:

  • Atmospheric model type

  • Extreme parameter

  • Frequency of occurrence

  • Altitude of extreme value

Programmatic Use

Block Parameter: spec
Type: character vector
Values: '1976 COESA-extended U.S. Standard Atmosphere' | 'MIL-HDBK-310' | 'MIL-STD-210C'
Default: '1976 COESA-extended U.S. Standard Atmosphere'

Representation of atmospheric model type, specified as:

ProfileRealistic atmospheric profiles associated with extremes at specified altitudes. Recommended for simulation of vehicles vertically traversing the atmosphere or when the total influence of the atmosphere is needed.
EnvelopeUses extreme atmospheric values at each altitude. Recommended for vehicles only horizontally traversing the atmosphere without much change in altitude.

Dependencies

  • Selecting MIL-HDBK-310 or MIL-STD-210C for the Specification parameter enables this parameter.

  • Selecting Profile enables the Attitude of extreme value parameter.

Programmatic Use

Block Parameter: model
Type: character vector
Values: 'Profile' | 'Envelope'
Default: 'Profile'

Atmospheric parameter that is the extreme value.

Dependencies

  • Selecting MIL-HDBK-310 or MIL-STD-210C for the Specification parameter enables this parameter.

  • The High pressure and Low pressure options appear only when Atmospheric model type is set to Envelope.

Programmatic Use

Block Parameter: profile_var
Type: character vector
Values: 'High temperature' | 'Low temperature' | 'High density' | 'Low density' | 'High pressure' | 'Low pressure'
Default: 'High temperature'

Percent of time the values would occur.

Dependencies

  • Selecting MIL-HDBK-310 or MIL-STD-210C for the Specification parameter enables this parameter.

  • Extreme values, 5%, and 20% are available only when Envelope is selected for Atmospheric model type.

  • 1% and 10% are always available.

Programmatic Use

Block Parameter: profile_percent
Type: character vector
Values: 'Extreme values' | '1%' | '5%' | '10%' | '20%'
Default: '1%'

Geometric altitude at which the extreme values occur, specified as 5 km (16404 ft), 10 km (32808 ft), 20 km (65617 ft), 30 km (98425 ft), or 40 km (131234 ft).

Dependencies

This parameter appears if the Atmospheric model type is set to Profile.

Programmatic Use

Block Parameter: profile_alt
Type: character vector
Values: 5 km (16404 ft) | 10 km (32808 ft) | 20 km (65617 ft) | 30 km (98425 ft) | 40 km (131234 ft)
Default: 40 km (131234 ft)

Out-of-range block behavior, specified as follows.

ActionDescription

None

No action.

Warning

Warning in the MATLAB® Command Window, model simulation continues.

Error (default)

MATLAB returns an exception, model simulation stops.

Programmatic Use

Block Parameter: action
Type: character vector
Values: 'None' | 'Warning' | 'Error'
Default: 'Warning'

References

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

Introduced before R2006a