# Incidence, Sideslip, & Airspeed

Calculate incidence, sideslip, and airspeed

• Libraries:
Aerospace Blockset / Flight Parameters

## Description

The Incidence, Sideslip, & Airspeed block calculates the angles between the velocity vector and the body, and also the total airspeed from the velocity components in the body-fixed coordinate frame. For the equations used in the calculation, see Algorithms.

## Ports

### Input

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Velocity of the body, specified as a three-element vector, resolved into the body-fixed coordinate frame.

Data Types: `double`

### Output

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Incidence angle, returned as a scalar, in radians.

Data Types: `double`

Sideslip angle, returned as a scalar, in radians.

Data Types: `double`

Airspeed of the body, returned as a scalar.

Data Types: `double`

## Algorithms

To calculate the angles between the velocity vector and the body, and the total airspeed, the block uses these equations:

`$\alpha ={\mathrm{tan}}^{-1}\left(\frac{w}{u}\right)$`
`$\beta ={\mathrm{sin}}^{-1}\left(\frac{v}{V}\right)={\mathrm{tan}}^{-1}\left(\frac{v}{\sqrt{{u}^{2}+{w}^{2}}}\right)$`

The block uses the `tan-1` formulation for β to prevent division by `0`.

`$V=\sqrt{{u}^{2}+{v}^{2}+{w}^{2}}$`

## Version History

Introduced before R2006a

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