FGAuxiliary

class jsbsim.FGAuxiliary

Encapsulates various uncategorized scheduled functions.

Pilot sensed accelerations are calculated here. This is used for the coordinated turn ball instrument. Motion base platforms sometimes use the derivative of pilot sensed accelerations as the driving parameter, rather than straight accelerations.

The theory behind pilot-sensed calculations is presented:

For purposes of discussion and calculation, assume for a minute that the pilot is in space and motionless in inertial space. She will feel no accelerations. If the aircraft begins to accelerate along any axis or axes (without rotating), the pilot will sense those accelerations. If any rotational moment is applied, the pilot will sense an acceleration due to that motion in the amount:

[wdot X R] + [w X (w X R)] Term I Term II

where:

wdot = omegadot, the rotational acceleration rate vector w = omega, the rotational rate vector R = the vector from the aircraft CG to the pilot eyepoint

The sum total of these two terms plus the acceleration of the aircraft body axis gives the acceleration the pilot senses in inertial space. In the presence of a large body such as a planet, a gravity field also provides an accelerating attraction. This acceleration can be transformed from the reference frame of the planet so as to be expressed in the frame of reference of the aircraft. This gravity field accelerating attraction is felt by the pilot as a force on her tushie as she sits in her aircraft on the runway awaiting takeoff clearance.

In JSBSim the acceleration of the body frame in inertial space is given by the F = ma relation. If the vForces vector is divided by the aircraft mass, the acceleration vector is calculated. The term wdot is equivalent to the JSBSim vPQRdot vector, and the w parameter is equivalent to vPQR.

get_Tb2w() → ndarray

Calculates and returns the body-to-wind axis transformation matrix.

Returns:

a reference to the wind-to-body transformation matrix.

get_Tw2b() → ndarray

Calculates and returns the wind-to-body axis transformation matrix.

Returns:

a reference to the wind-to-body transformation matrix.