# Available Torque Models

In this page, all the torque models available in Tudat are explained. Regardless of the type of torque model, the procedure to link such torque model to the bodies exerting and undergoing the torque is explained in this page: Torque Model Setup. Therefore, this information will not be repeated in this page. Instead, for each model, a reference to the related API documentation entry and the requirements are provided.

Note

In Tudat, torque models are defined through factory functions, which define the properties required of
the torques, but do not perform any calculations themselves. These properties are stored through instances
of the `TorqueSettings`

class or of its
derived classes.

List of available torque models

In certain pieces of code, such as when requesting the saving of a single torque (see Dependent Variables
for saving of dependent variables), you will need to supply an identifier for the type of torque you are requesting.
See the list of supported identifier types in the API documentation:
`AvailableTorque`

.

## Aerodynamic Torque

**Description**

`aerodynamic()`

factory function.**Dependencies**

Note

The aerodynamic acceleration is calculated in the vehicles body-fixed or aerodynamic frame. Expressing the
acceleration in an inertial frame (as required by the propagation) requires the vehicle’s orientation to be defined.
For a simple definition, in which the body’s angle of attack, sideslip angle, and bank angle are all set to 0, see
`aerodynamic_angle_based()`

.

More details on aerodynamic guidance can be found on this page.

## Second Degree Gravitational Torque

**Description**

`second_degree_gravitational()`

factory function.**Dependencies**

Tip

This implementation of the gravitational torque model uses the inertia tensor if the body undergoing the torque to infer its degree two spherical harmonics gravity field. It is therefore convenient for modelling the gravitational torque acting on a custom body, such as a vehicle, because its custom spherical harmonics model does not have to be created manually.

## Spherical Harmonics Gravitational Torque

**Description**

`spherical_harmonic_gravitational()`

factory function.**Dependencies**

Tip

In contrast to the second degree gravitational torque, the spherical harmonics gravity torque implementation requires the spherical harmonics gravity field model of the torque-undergoing body. It is therefore more suited for modelling the gravity torques acting on “standard” celestial bodies, for which spherical harmonics mass distributions are readily available.

## Custom Torque

**Description**

`custom()`

factory function.**Dependencies**