Radius at Geocentric Latitude

Estimate radius of ellipsoid planet at geocentric latitude

Library

Flight Parameters

Description

The Radius at Geocentric Latitude block estimates the radius $$(r_s)$$ of an ellipsoid planet at a particular geocentric latitude $$({\lambda }_s)$$.

The following equation estimates the ellipsoid radius $$(r_s)$$ using flattening $$(\overline{f})$$, geocentric latitude $$({\overline{\lambda }}_s)$$, and equatorial radius $$(\overline{R})$$.

$$r_s=\sqrt{\frac{R^2}{1+\left[1/{(1-f)}^2-1\right]{\sin }^2{\lambda }_s}}$$

Parameters

Units

Specifies the parameter and output units:

Units	Equatorial Radius	Radius at Geocentric Latitude
Metric (MKS)	Meters	Meters
English	Feet	Feet

This option is only available when Planet model is set to Earth (WGS84).

Planet model

Specifies the planet model to use:

Custom

Earth (WGS84)

Flattening

Specifies the flattening of the planet. This option is only available with Planet model set to Custom.

Equatorial radius of planet

Specifies the radius of the planet at its equator. This option is only available with Planet model set to Custom.

Inputs and Outputs

Input	Dimension Type	Description
First		Contains the geocentric latitude, in degrees.

Output	Dimension Type	Description
First		Contains the radius of planet at geocentric latitude, in the same as the units as flattening.

References

Stevens, B. L., and F. L. Lewis, Aircraft Control and Simulation, John Wiley & Sons, New York, 1992.

Zipfel, P. H., Modeling and Simulation of Aerospace Vehicle Dynamics, AIAA Education Series, Reston, Virginia, 2000.