4th Order Point Mass (Longitudinal)

Calculate fourth-order point mass

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Libraries:
Aerospace Blockset / Equations of Motion / Point Mass

Description

The 4th Order Point Mass (Longitudinal) block performs the calculations for the translational motion of a single point mass or multiple point masses. For more information on the system for the translational motion of a single point mass or multiple mass, see Algorithms.

The 4th Order Point Mass (Longitudinal) block port labels change based on the input and output units selected from the Units list.

Limitations

The flat Earth reference frame is considered inertial, an approximation that allows the forces due to the Earth's motion relative to the “fixed stars” to be neglected.

Ports

Input

Port_1 — Force in x-axis

scalar | array

Force in x-axis, specified as a scalar or array, in selected units.

Data Types: double

Port_2 — Force in z-axis

scalar | array

Force in z-axis, specified as a scalar or array, in selected units.

Data Types: double

Output

Port_1 — Flight path angle

scalar | array

Flight path angle, returned as a scalar or array, in radians.

Data Types: double

Port_2 — Airspeed

scalar | array

Airspeed, returned as a scalar or array, in selected units.

Data Types: double

Port_3 — Downrange or amount traveled east

scalar | array

Downrange or amount traveled east, returned as a scalar or array, in selected units.

Data Types: double

Port_4 — Altitude or amount traveled up

scalar | array

Altitude or amount traveled up, returned as a scalar or array, in selected units.

Data Types: double

Parameters

Units — Units

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

Input and output units, specified as:

Units	Forces	Velocity	Position	Mass
Metric (MKS)	newtons	meters per second	meters	kilograms
English (Velocity in ft/s)	pounds	feet per second	feet	slugs
English (Velocity in kts)	pounds	knots	feet	slugs

Programmatic Use

Block Parameter: units

Type: character vector

Values: 'Metric (MKS)' | 'English (Velocity in ft/s)' | 'English (Velocity in kts)'

Default: 'Metric (MKS)'

Initial flight path angle — Initial flight path angle

0 (default) | scalar | vector

Initial flight path angle of the point mass(es), specified as a scalar or vector.

Programmatic Use

Block Parameter: gamma0

Type: character vector

Values: scalar | vector

Default: '0'

Initial airspeed — Initial airspeed

100 (default) | scalar | vector

Initial airspeed of the point mass(es), specified as a scalar or vector.

Programmatic Use

Block Parameter: V0

Type: character vector

Values: scalar | vector

Default: '100'

Initial downrange [East] — Initial downrange

0 (default) | scalar | vector

Initial downrange of the point mass(es), specified as a scalar or vector.

Programmatic Use

Block Parameter: x0

Type: character vector

Values: scalar | vector

Default: '0'

Initial altitude [Up] — Initial altitude of point masses

0 (default) | scalar | vector

Initial altitude of the point mass(es), specified as a scalar or vector.

Programmatic Use

Block Parameter: h0

Type: character vector

Values: scalar | vector

Default: '0'

Initial mass — Point mass

1.0 (default) | scalar | vector

Mass of the point mass(es), specified as a scalar or vector.

Programmatic Use

Block Parameter: mass0

Type: character vector

Values: scalar | vector

Default: '1.0'

Algorithms

The translational motions of the point mass [X_EastX_Up]^T are functions of airspeed (V) and flight path angle (γ),

$$\begin{array}{c}{F}_x=m\dot{V}\\ F_z=mV\dot{\gamma }\\ {\dot{X}}_{East}=V\cos \gamma \\ {\dot{X}}_{Up}=V\sin \gamma \end{array}$$

where the applied forces [F_xF_z]^T are in a system defined as follows: x-axis is in the direction of vehicle velocity relative to air, z-axis is upward, and y-axis completes the right-handed frame. The mass of the body m is assumed constant.

Extended Capabilities

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

Version History

Introduced before R2006a