FGAuxiliary Class Reference

#include <FGAuxiliary.h>

Inherits FGModel.

List of all members.


Detailed Description

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. The radius R is calculated below in the vector vToEyePt.

Author:
Tony Peden, Jon Berndt
Version:
Id
FGAuxiliary.h,v 1.14 2009/05/17 13:50:14 jberndt Exp

Definition at line 111 of file FGAuxiliary.h.


Public Member Functions

 FGAuxiliary (FGFDMExec *Executive)
 Constructor.
double Getadot (int unit) const
double Getadot (void) const
const FGColumnVector3GetAeroPQR (void) const
double GetAeroPQR (int axis) const
double GetAeroUVW (int idx) const
const FGColumnVector3GetAeroUVW (void) const
double Getalpha (int unit) const
double Getalpha (void) const
double Getbdot (int unit) const
double Getbdot (void) const
double Getbeta (int unit) const
double Getbeta (void) const
double GetCrossWind (void) const
int GetDayOfYear (void) const
double GetDistanceRelativePosition (void) const
const FGColumnVector3GetEulerRates (void) const
double GetEulerRates (int axis) const
double GetGamma (void) const
double GetGroundTrack (void) const
double GetHeadWind (void) const
double GetHOverBCG (void) const
double GetHOverBMAC (void) const
double GethVRP (void) const
double GetLatitudeRelativePosition (void) const
const FGLocationGetLocationVRP (void) const
double GetLongitudeRelativePosition (void) const
double GetMach (void) const
 Gets the Mach number.
double GetMachU (void) const
 The mach number calculated using the vehicle X axis velocity.
double GetMagBeta (int unit) const
double GetMagBeta (void) const
const FGColumnVector3GetNpilot (void) const
double GetNpilot (int idx) const
double GetNz (void) const
 The vertical acceleration in g's of the aircraft center of gravity.
const FGColumnVector3GetPilotAccel (void) const
double GetPilotAccel (int idx) const
double Getqbar (void) const
double GetqbarUV (void) const
double GetqbarUW (void) const
double GetReynoldsNumber (void) const
double GetSecondsInDay (void) const
double GetTAT_C (void) const
double GetTotalPressure (void) const
 Returns the total pressure.
double GetTotalTemperature (void) const
 Returns the total temperature.
double GetVcalibratedFPS (void) const
 Returns Calibrated airspeed in feet/second.
double GetVcalibratedKTS (void) const
 Returns Calibrated airspeed in knots.
double GetVequivalentFPS (void) const
 Returns equivalent airspeed in feet/second.
double GetVequivalentKTS (void) const
 Returns equivalent airspeed in knots.
double GetVground (void) const
 Gets the ground speed in feet per second.
double GetVt (void) const
 Gets the magnitude of total vehicle velocity including wind effects in feet per second.
bool InitModel (void)
bool Run (void)
 Runs the Auxiliary routines; called by the Executive.
void SetAB (double t1, double t2)
void Setadot (double tt)
void SetAeroPQR (FGColumnVector3 tt)
void SetAeroUVW (FGColumnVector3 tt)
void Setalpha (double tt)
void Setbdot (double tt)
void Setbeta (double tt)
void SetDayOfYear (int doy)
void SetGamma (double tt)
void SetMach (double tt)
void Setqbar (double tt)
void SetqbarUV (double tt)
void SetqbarUW (double tt)
void SetSecondsInDay (double sid)
void SetVt (double tt)
 ~FGAuxiliary ()
 Destructor.

Constructor & Destructor Documentation

FGAuxiliary ( FGFDMExec Executive  ) 

Parameters:
Executive a pointer to the parent executive object

Definition at line 66 of file FGAuxiliary.cpp.


Member Function Documentation

double GetMach ( void   )  const [inline]

Definition at line 200 of file FGAuxiliary.h.

double GetMachU ( void   )  const [inline]

Definition at line 203 of file FGAuxiliary.h.

double GetNz ( void   )  const [inline]

Definition at line 206 of file FGAuxiliary.h.

double GetTotalPressure ( void   )  const [inline]

Total pressure is freestream total pressure for subsonic only. For supersonic it is the 1D total pressure behind a normal shock.

Definition at line 142 of file FGAuxiliary.h.

double GetTotalTemperature ( void   )  const [inline]

The total temperature ("tat", isentropic flow) is calculated:

    tat = sat*(1 + 0.2*Mach*Mach)
(where "sat" is standard temperature)

Definition at line 151 of file FGAuxiliary.h.

double GetVcalibratedFPS ( void   )  const [inline]

Definition at line 130 of file FGAuxiliary.h.

double GetVcalibratedKTS ( void   )  const [inline]

Definition at line 132 of file FGAuxiliary.h.

double GetVequivalentFPS ( void   )  const [inline]

Definition at line 134 of file FGAuxiliary.h.

double GetVequivalentKTS ( void   )  const [inline]

Definition at line 136 of file FGAuxiliary.h.

double GetVground ( void   )  const [inline]

The magnitude is the square root of the sum of the squares (RSS) of the vehicle north and east velocity components.

Returns:
The magnitude of the vehicle velocity in the horizontal plane.

Definition at line 197 of file FGAuxiliary.h.

double GetVt ( void   )  const [inline]

Definition at line 191 of file FGAuxiliary.h.

bool Run ( void   )  [virtual]

Returns:
false if no error

Reimplemented from FGModel.

Definition at line 134 of file FGAuxiliary.cpp.


The documentation for this class was generated from the following files:

Generated on Tue May 26 00:55:09 2009 for JSBSim Flight Dynamics Model by  doxygen 1.5.5