COESA Atmosphere Model

Implement 1976 COESA lower atmosphere

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Libraries:
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.

Examples

True Airspeed from Indicated Airspeed Calculation

Compute the indicated airspeed from true airspeed using the Ideal Airspeed Correction block.

• Open Live Script

Indicated Airspeed from True Airspeed Calculation

Compute the indicated airspeed from true airspeed using the Ideal Airspeed Correction block.

• Open Live Script

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

Port_1 — Geopotential height

scalar | array

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

Data Types: double

Output

Port_1 — Temperature

scalar | array

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

Data Types: double

Port_2 — Speed of sound

scalar | array

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

Data Types: double

Port_3 — Air pressure

scalar | array

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

Data Types: double

Port_4 — Air density

scalar | array

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

Data Types: double

Parameters

Units — Input and output units

Metric (MKS) (default) | English (Velocity in ft/s) | English (Velocity in kts)

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)'

Specification — Atmosphere model type

1976 COESA-extended U.S. Standard Atmosphere (default) | MIL-HDBK-310 | MIL-STD-210C

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 310 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'

Atmospheric model type — Model type

Profile (default) | Envelope

Representation of atmospheric model type, specified as:

Profile	Realistic 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.
Envelope	Uses 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'

Extreme parameter — Model type

High temperature (default) | Low temperature | High density | Low density | High pressure | Low pressure

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'

Frequency of occurrence — Model type

1% (default) | Extreme values | 5% | 10% | 20%

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%'

Altitude of extreme value — Geometric altitude

5 km (16404 ft) (default) | 10 km (32808 ft) | 20 km (65617 ft) | 30 km (98425 ft) | 40 km (131234 ft)

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)

Action for out-of-range input — Out-of-range block behavior

None (default) | Warning | Error

Out-of-range block behavior, specified as:

Action	Description
None	No action.
Warning	Warning in the Diagnostic Viewer, model simulation continues.
Error (default)	Error in the Diagnostic Viewer, 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.

Extended Capabilities

C/C++ Code Generation
Generate C and C++ code using Simulink® Coder™.

Version History

Introduced before R2006a