4th Order Point Mass (Longitudinal)

Calculate fourth-order point mass

  • Library:
  • 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.

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

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

Data Types: double

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

Data Types: double

Output

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

Data Types: double

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

Data Types: double

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

Data Types: double

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

Data Types: double

Parameters

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Input and output units, specified as:

Units

Forces

Velocity

Position

Metric (MKS)

Newton

Meters per second

Meters

English (Velocity in ft/s)

Pound

Feet per second

Feet

English (Velocity in kts)

Pound

Knots

Feet

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

Programmatic Use

Block Parameter: h0
Type: character vector
Values: scalar | vector
Default: '0'

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 [XEastXUp]T are functions of airspeed (V) and flight path angle (γ),

Fx=mV˙Fz=mVγ˙X˙East=VcosγX˙Up=Vsinγ

where the applied forces [FxFz]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.

Introduced before R2006a