Detailed Description

Handles the calculation of accelerations.

Calculate the angular accelerations
Calculate the translational accelerations

This class is collecting all the forces and the moments acting on the body to calculate the corresponding accelerations according to Newton's second law. This is also where the friction forces related to the ground reactions are evaluated.

JSBSim provides several ways to calculate the influence of the gravity on the vehicle. The different options can be selected via the following properties :

simulation/gravity-model (read/write) Selects the gravity model. Two options are available : 0 (Standard gravity assuming the Earth is spherical) or 1 (WGS84 gravity taking the Earth oblateness into account). WGS84 gravity is the default.
simulation/gravitational-torque (read/write) Enables/disables the calculations of the gravitational torque on the vehicle. This is mainly relevant for spacecrafts that are orbiting at low altitudes. Gravitational torque calculations are disabled by default.

Special care is taken in the calculations to obtain maximum fidelity in JSBSim results. In FGAccelerations, this is obtained by avoiding as much as possible the transformations from one frame to another. As a consequence, the frames in which the accelerations are primarily evaluated are dictated by the frames in which FGPropagate resolves the equations of movement (the ECI frame for the translations and the body frame for the rotations).

See also: Mark Harris and Robert Lyle, "Spacecraft Gravitational Torques", NASA SP-8024, May 1969

Author: Jon S. Berndt, Mathias Froehlich, Bertrand Coconnier

Definition at line 95 of file FGAccelerations.h.

#include <FGAccelerations.h>

Inheritance diagram for FGAccelerations:

Collaboration diagram for FGAccelerations:

Classes
struct	Inputs

Public Member Functions
	FGAccelerations (FGFDMExec *Executive)
	Constructor. More...

	~FGAccelerations ()
	Destructor.

double	GetBodyAccel (int idx) const
	Retrieves a component of the acceleration resulting from the applied forces. More...

const FGColumnVector3 &	GetBodyAccel (void) const
	Retrieves the acceleration resulting from the applied forces. More...

double	GetForces (int idx) const
	Retrieves the total forces applied on the body. More...

FGColumnVector3	GetForces (void) const

double	GetGravAccelMagnitude (void) const

double	GetGroundForces (int idx) const
	Retrieves the ground forces applied on the body. More...

FGColumnVector3	GetGroundForces (void) const

double	GetGroundMoments (int idx) const
	Retrieves the ground moments applied on the body. More...

FGColumnVector3	GetGroundMoments (void) const

double	GetMoments (int idx) const
	Retrieves a component of the total moments applied on the body. More...

FGColumnVector3	GetMoments (void) const

double	GetPQRdot (int axis) const
	Retrieves a body frame angular acceleration component. More...

const FGColumnVector3 &	GetPQRdot (void) const
	Retrieves the body axis angular acceleration vector. More...

const FGColumnVector3 &	GetPQRidot (void) const
	Retrieves the axis angular acceleration vector in the ECI frame. More...

double	GetUVWdot (int idx) const
	Retrieves a body frame acceleration component. More...

const FGColumnVector3 &	GetUVWdot (void) const
	Retrieves the body axis acceleration. More...

const FGColumnVector3 &	GetUVWidot (void) const
	Retrieves the body axis acceleration in the ECI frame. More...

double	GetWeight (int idx) const
	Retrieves the weight applied on the body. More...

FGColumnVector3	GetWeight (void) const

void	InitializeDerivatives (void)
	Initializes the FGAccelerations class prior to a new execution. More...

bool	InitModel (void) override
	Initializes the FGAccelerations class after instantiation and prior to first execution. More...

bool	Run (bool Holding) override
	Runs the state propagation model; called by the Executive Can pass in a value indicating if the executive is directing the simulation to Hold. More...

void	SetHoldDown (bool hd)
	Sets the property forces/hold-down. More...

Public Member Functions inherited from FGModel
	FGModel (FGFDMExec *)
	Constructor.

	~FGModel () override
	Destructor.

virtual SGPath	FindFullPathName (const SGPath &path) const

FGFDMExec *	GetExec (void)

const std::string &	GetName (void)

unsigned int	GetRate (void)
	Get the output rate for the model in frames.

bool	InitModel (void) override

virtual bool	Load (Element *el)

void	SetPropertyManager (std::shared_ptr< FGPropertyManager > fgpm)

void	SetRate (unsigned int tt)
	Set the ouput rate for the model in frames.

Public Member Functions inherited from FGModelFunctions
std::string	GetFunctionStrings (const std::string &delimeter) const
	Gets the strings for the current set of functions. More...

std::string	GetFunctionValues (const std::string &delimeter) const
	Gets the function values. More...

std::shared_ptr< FGFunction >	GetPreFunction (const std::string &name)
	Get one of the "pre" function. More...

bool	Load (Element el, FGFDMExec fdmex, std::string prefix="")

void	PostLoad (Element el, FGFDMExec fdmex, std::string prefix="")

void	PreLoad (Element el, FGFDMExec fdmex, std::string prefix="")

void	RunPostFunctions (void)

void	RunPreFunctions (void)

Public Member Functions inherited from FGJSBBase
	FGJSBBase ()
	Constructor for FGJSBBase.

virtual	~FGJSBBase ()
	Destructor for FGJSBBase.

void	disableHighLighting (void)
	Disables highlighting in the console output.

Public Attributes
struct JSBSim::FGAccelerations::Inputs	in

Additional Inherited Members
Public Types inherited from FGJSBBase
enum	{ eL = 1 , eM , eN }
	Moments L, M, N.

enum	{ eP = 1 , eQ , eR }
	Rates P, Q, R.

enum	{ eU = 1 , eV , eW }
	Velocities U, V, W.

enum	{ eX = 1 , eY , eZ }
	Positions X, Y, Z.

enum	{ ePhi = 1 , eTht , ePsi }
	Euler angles Phi, Theta, Psi.

enum	{ eDrag = 1 , eSide , eLift }
	Stability axis forces, Drag, Side force, Lift.

enum	{ eRoll = 1 , ePitch , eYaw }
	Local frame orientation Roll, Pitch, Yaw.

enum	{ eNorth = 1 , eEast , eDown }
	Local frame position North, East, Down.

enum	{ eLat = 1 , eLong , eRad }
	Locations Radius, Latitude, Longitude.

enum	{ inNone = 0 , inDegrees , inRadians , inMeters , inFeet }
	Conversion specifiers.

Static Public Member Functions inherited from FGJSBBase
static const std::string &	GetVersion (void)
	Returns the version number of JSBSim. More...

static constexpr double	KelvinToFahrenheit (double kelvin)
	Converts from degrees Kelvin to degrees Fahrenheit. More...

static constexpr double	CelsiusToRankine (double celsius)
	Converts from degrees Celsius to degrees Rankine. More...

static constexpr double	RankineToCelsius (double rankine)
	Converts from degrees Rankine to degrees Celsius. More...

static constexpr double	KelvinToRankine (double kelvin)
	Converts from degrees Kelvin to degrees Rankine. More...

static constexpr double	RankineToKelvin (double rankine)
	Converts from degrees Rankine to degrees Kelvin. More...

static constexpr double	FahrenheitToCelsius (double fahrenheit)
	Converts from degrees Fahrenheit to degrees Celsius. More...

static constexpr double	CelsiusToFahrenheit (double celsius)
	Converts from degrees Celsius to degrees Fahrenheit. More...

static constexpr double	CelsiusToKelvin (double celsius)
	Converts from degrees Celsius to degrees Kelvin. More...

static constexpr double	KelvinToCelsius (double kelvin)
	Converts from degrees Kelvin to degrees Celsius. More...

static constexpr double	FeetToMeters (double measure)
	Converts from feet to meters. More...

static bool	EqualToRoundoff (double a, double b)
	Finite precision comparison. More...

static bool	EqualToRoundoff (float a, float b)
	Finite precision comparison. More...

static bool	EqualToRoundoff (float a, double b)
	Finite precision comparison. More...

static bool	EqualToRoundoff (double a, float b)
	Finite precision comparison. More...

static constexpr double	Constrain (double min, double value, double max)
	Constrain a value between a minimum and a maximum value.

static constexpr double	sign (double num)

Static Public Attributes inherited from FGJSBBase
static char	highint [5] = {27, '[', '1', 'm', '\0' }
	highlights text

static char	halfint [5] = {27, '[', '2', 'm', '\0' }
	low intensity text

static char	normint [6] = {27, '[', '2', '2', 'm', '\0' }
	normal intensity text

static char	reset [5] = {27, '[', '0', 'm', '\0' }
	resets text properties

static char	underon [5] = {27, '[', '4', 'm', '\0' }
	underlines text

static char	underoff [6] = {27, '[', '2', '4', 'm', '\0' }
	underline off

static char	fgblue [6] = {27, '[', '3', '4', 'm', '\0' }
	blue text

static char	fgcyan [6] = {27, '[', '3', '6', 'm', '\0' }
	cyan text

static char	fgred [6] = {27, '[', '3', '1', 'm', '\0' }
	red text

static char	fggreen [6] = {27, '[', '3', '2', 'm', '\0' }
	green text

static char	fgdef [6] = {27, '[', '3', '9', 'm', '\0' }
	default text

static short	debug_lvl = 1

Protected Member Functions inherited from FGModel
bool	Upload (Element *el, bool preLoad)
	Uploads this model in memory. More...

Static Protected Member Functions inherited from FGJSBBase
static std::string	CreateIndexedPropertyName (const std::string &Property, int index)

Protected Attributes inherited from FGModel
unsigned int	exe_ctr

FGFDMExec *	FDMExec

std::string	Name

std::shared_ptr< FGPropertyManager >	PropertyManager

unsigned int	rate

Protected Attributes inherited from FGModelFunctions
FGPropertyReader	LocalProperties

std::vector< std::shared_ptr< FGFunction > >	PostFunctions

std::vector< std::shared_ptr< FGFunction > >	PreFunctions

Static Protected Attributes inherited from FGJSBBase
static constexpr double	radtodeg = 180. / M_PI

static constexpr double	degtorad = M_PI / 180.

static constexpr double	hptoftlbssec = 550.0

static constexpr double	psftoinhg = 0.014138

static constexpr double	psftopa = 47.88

static constexpr double	fttom = 0.3048

static constexpr double	ktstofps = 1852./(3600*fttom)

static constexpr double	fpstokts = 1.0 / ktstofps

static constexpr double	inchtoft = 1.0/12.0

static constexpr double	m3toft3 = 1.0/(fttomfttomfttom)

static constexpr double	in3tom3 = inchtoftinchtoftinchtoft/m3toft3

static constexpr double	inhgtopa = 3386.38

static constexpr double	slugtolb = 32.174049
	Note that definition of lbtoslug by the inverse of slugtolb and not to a different constant you can also get from some tables will make lbtoslug*slugtolb == 1 up to the magnitude of roundoff. More...

static constexpr double	lbtoslug = 1.0/slugtolb

static constexpr double	kgtolb = 2.20462

static constexpr double	kgtoslug = 0.06852168

static const std::string	needed_cfg_version = "2.0"

static const std::string	JSBSim_version = JSBSIM_VERSION " " __DATE__ " " __TIME__

Constructor & Destructor Documentation

◆ FGAccelerations()

FGAccelerations ( FGFDMExec * Executive )

explicit

Constructor.

Parameters

Executive a pointer to the parent executive object

Definition at line 67 of file FGAccelerations.cpp.

   : FGModel(fdmex)
 {
   Debug(0);
   Name = "FGAccelerations";
   gravTorque = false;
  
   vPQRidot.InitMatrix();
   vUVWidot.InitMatrix();
   vUVWdot.InitMatrix();
   vBodyAccel.InitMatrix();
  
   bind();
   Debug(0);
 }

Member Function Documentation

◆ GetBodyAccel() [1/2]

double GetBodyAccel ( int idx ) const

inline

Retrieves a component of the acceleration resulting from the applied forces.

Retrieves a component of the ratio between the sum of all forces applied on the craft to its mass. The value returned is extracted from the vBodyAccel vector (an FGColumnVector3). The vector for the acceleration in Body frame is organized (Ax, Ay, Az). The vector is 1-based. In other words, GetBodyAccel(1) returns Ax. Various convenience enumerators are defined in FGJSBBase. The relevant enumerators for the vector returned by this call are, eX=1, eY=2, eZ=3. units ft/sec^2

Parameters

idx	the index of the acceleration component desired (1-based).

Returns: The component of the acceleration resulting from the applied forces.

Definition at line 219 of file FGAccelerations.h.

219 { return vBodyAccel(idx); }

◆ GetBodyAccel() [2/2]

const FGColumnVector3& GetBodyAccel ( void ) const

inline

Retrieves the acceleration resulting from the applied forces.

Retrieves the ratio of the sum of all forces applied on the craft to its mass. This does include the friction forces but not the gravity. The vector returned is represented by an FGColumnVector3 reference. The vector for the acceleration in Body frame is organized (Ax, Ay, Az). The vector is 1-based, so that the first element can be retrieved using the "()" operator. In other words, vBodyAccel(1) is Ax. Various convenience enumerators are defined in FGJSBBase. The relevant enumerators for the vector returned by this call are, eX=1, eY=2, eZ=3. units ft/sec^2

Returns: The acceleration resulting from the applied forces.

Definition at line 203 of file FGAccelerations.h.

203 { return vBodyAccel; }

◆ GetForces()

double GetForces ( int idx ) const

inline

Retrieves the total forces applied on the body.

Retrieves the total forces applied on the body. This does include the friction forces but not the gravity. The vector for the total forces in the body frame is organized (Fx, Fy , Fz). The vector is 1-based. In other words, GetForces(1) returns Fx. Various convenience enumerators are defined in FGJSBBase. The relevant enumerators for the forces returned by this call are, eX=1, eY=2, eZ=3. units lbs

Parameters

idx	the index of the forces component desired (1-based).

Returns: The total forces applied on the body.

Definition at line 261 of file FGAccelerations.h.

261 { return in.Force(idx) + vFrictionForces(idx); }

JSBSim::FGAccelerations::Inputs::Force

FGColumnVector3 Force

Total forces applied to the body except friction and gravity (expressed in the body frame)

Definition: FGAccelerations.h:336

◆ GetGroundForces()

double GetGroundForces ( int idx ) const

inline

Retrieves the ground forces applied on the body.

Retrieves the ground forces applied on the body. This does include the ground normal reaction and friction forces. The vector for the ground forces in the body frame is organized (Fx, Fy , Fz). The vector is 1-based. In other words, GetGroundForces(1) returns Fx. Various convenience enumerators are defined in FGJSBBase. The relevant enumerators for the forces returned by this call are, eX=1, eY=2, eZ=3. units lbs.

Parameters

idx	the index of the forces component desired (1-based).

Returns: The ground forces applied on the body.

Definition at line 289 of file FGAccelerations.h.

289 { return in.GroundForce(idx) + vFrictionForces(idx); }

JSBSim::FGAccelerations::Inputs::GroundForce

FGColumnVector3 GroundForce

Forces generated by the ground normal reactions expressed in the body frame. Does not account for fri...

Definition: FGAccelerations.h:338

◆ GetGroundMoments()

double GetGroundMoments ( int idx ) const

inline

Retrieves the ground moments applied on the body.

Retrieves the ground moments applied on the body. This does include the ground normal reaction and friction moments. The vector for the ground moments in the body frame is organized (Mx, My , Mz). The vector is 1-based. In other words, GetGroundMoments(1) returns Mx. Various convenience enumerators are defined in FGJSBBase. The relevant enumerators for the moments returned by this call are, eX=1, eY=2, eZ=3. units lbs*ft

Parameters

idx	the index of the moments component desired (1-based).

Returns: The ground moments applied on the body.

Definition at line 275 of file FGAccelerations.h.

275 { return in.GroundMoment(idx) + vFrictionMoments(idx); }

JSBSim::FGAccelerations::Inputs::GroundMoment

FGColumnVector3 GroundMoment

Moments generated by the ground normal reactions expressed in the body frame. Does not account for fr...

Definition: FGAccelerations.h:334

◆ GetMoments()

double GetMoments ( int idx ) const

inline

Retrieves a component of the total moments applied on the body.

Retrieves a component of the total moments applied on the body. This does include the moments generated by friction forces and the gravitational torque (if the property simulation/gravitational-torque is set to true). The vector for the total moments in the body frame is organized (Mx, My , Mz). The vector is 1-based. In other words, GetMoments(1) returns Mx. Various convenience enumerators are defined in FGJSBBase. The relevant enumerators for the moments returned by this call are, eX=1, eY=2, eZ=3. units lbs*ft

Parameters

idx	the index of the moments component desired (1-based).

Returns: The total moments applied on the body.

Definition at line 247 of file FGAccelerations.h.

247 { return in.Moment(idx) + vFrictionMoments(idx); }

JSBSim::FGAccelerations::Inputs::Moment

FGColumnVector3 Moment

Total moments applied to the body except friction and gravity (expressed in the body frame)

Definition: FGAccelerations.h:332

◆ GetPQRdot() [1/2]

double GetPQRdot ( int axis ) const

inline

Retrieves a body frame angular acceleration component.

Retrieves a body frame angular acceleration component. The angular acceleration returned is extracted from the vPQRdot vector (an FGColumnVector3). The vector for the angular acceleration in Body frame is organized (Pdot, Qdot, Rdot). The vector is 1-based. In other words, GetPQRdot(1) returns Pdot (roll acceleration). Various convenience enumerators are defined in FGJSBBase. The relevant enumerators for the angular acceleration returned by this call are, eP=1, eQ=2, eR=3. units rad/sec^2

Parameters

axis	the index of the angular acceleration component desired (1-based).

Returns: The body frame angular acceleration component.

Definition at line 233 of file FGAccelerations.h.

233 {return vPQRdot(axis);}

◆ GetPQRdot() [2/2]

const FGColumnVector3& GetPQRdot ( void ) const

inline

Retrieves the body axis angular acceleration vector.

Retrieves the body axis angular acceleration vector in rad/sec^2. The angular acceleration vector is determined from the applied moments and accounts for a rotating frame. The vector returned is represented by an FGColumnVector3 reference. The vector for the angular acceleration in Body frame is organized (Pdot, Qdot, Rdot). The vector is 1-based, so that the first element can be retrieved using the "()" operator. In other words, vPQRdot(1) is Pdot. Various convenience enumerators are defined in FGJSBBase. The relevant enumerators for the vector returned by this call are, eP=1, eQ=2, eR=3. units rad/sec^2

Returns: The angular acceleration vector.

Definition at line 161 of file FGAccelerations.h.

161 {return vPQRdot;}

◆ GetPQRidot()

const FGColumnVector3& GetPQRidot ( void ) const

inline

Retrieves the axis angular acceleration vector in the ECI frame.

Retrieves the body axis angular acceleration vector measured in the ECI frame and expressed in the body frame. The angular acceleration vector is determined from the applied moments. The vector returned is represented by an FGColumnVector3 reference. The vector for the angular acceleration in Body frame is organized (Pidot, Qidot, Ridot). The vector is 1-based, so that the first element can be retrieved using the "()" operator. In other words, vPQRidot(1) is Pidot. Various convenience enumerators are defined in FGJSBBase. The relevant enumerators for the vector returned by this call are, eP=1, eQ=2, eR=3. units rad/sec^2

Returns: The angular acceleration vector.

Definition at line 176 of file FGAccelerations.h.

176 {return vPQRidot;}

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◆ GetUVWdot() [1/2]

double GetUVWdot ( int idx ) const

inline

Retrieves a body frame acceleration component.

Retrieves a body frame acceleration component. The acceleration returned is extracted from the vUVWdot vector (an FGColumnVector3). The vector for the acceleration in Body frame is organized (Ax, Ay, Az). The vector is 1-based. In other words, GetUVWdot(1) returns Ax. Various convenience enumerators are defined in FGJSBBase. The relevant enumerators for the acceleration returned by this call are, eX=1, eY=2, eZ=3. units ft/sec^2

Parameters

idx	the index of the acceleration component desired (1-based).

Returns: The body frame acceleration component.

Definition at line 189 of file FGAccelerations.h.

189 { return vUVWdot(idx); }

◆ GetUVWdot() [2/2]

const FGColumnVector3& GetUVWdot ( void ) const

inline

Retrieves the body axis acceleration.

Retrieves the computed body axis accelerations based on the applied forces and accounting for a rotating body frame. The vector returned is represented by an FGColumnVector3 reference. The vector for the acceleration in Body frame is organized (Ax, Ay, Az). The vector is 1-based, so that the first element can be retrieved using the "()" operator. In other words, vUVWdot(1) is Ax. Various convenience enumerators are defined in FGJSBBase. The relevant enumerators for the vector returned by this call are, eX=1, eY=2, eZ=3. units ft/sec^2

Returns: Body axis translational acceleration in ft/sec^2.

Definition at line 130 of file FGAccelerations.h.

130 { return vUVWdot; }

◆ GetUVWidot()

const FGColumnVector3& GetUVWidot ( void ) const

inline

Retrieves the body axis acceleration in the ECI frame.

Retrieves the computed body axis accelerations based on the applied forces. The ECI frame being an inertial frame this vector does not contain the Coriolis and centripetal accelerations. The vector is expressed in the Body frame. The vector returned is represented by an FGColumnVector3 reference. The vector for the acceleration in Body frame is organized (Aix, Aiy, Aiz). The vector is 1-based, so that the first element can be retrieved using the "()" operator. In other words, vUVWidot(1) is Aix. Various convenience enumerators are defined in FGJSBBase. The relevant enumerators for the vector returned by this call are, eX=1, eY=2, eZ=3. units ft/sec^2

Returns: Body axis translational acceleration in ft/sec^2.

Definition at line 146 of file FGAccelerations.h.

146 { return vUVWidot; }

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◆ GetWeight()

double GetWeight ( int idx ) const

inline

Retrieves the weight applied on the body.

Retrieves the weight applied on the body i.e. the force that results from the gravity applied to the body mass. The vector for the weight forces in the body frame is organized (Fx, Fy , Fz). The vector is 1-based. In other words, GetWeight(1) returns Fx. Various convenience enumerators are defined in FGJSBBase. The relevant enumerators for the forces returned by this call are, eX=1, eY=2, eZ=3. units lbs.

Parameters

idx	the index of the forces component desired (1-based).

Returns: The ground forces applied on the body.

Definition at line 303 of file FGAccelerations.h.

303 { return in.Mass * (in.Tec2b * in.vGravAccel)(idx); }

JSBSim::FGAccelerations::Inputs::vGravAccel

FGColumnVector3 vGravAccel

Gravity intensity vector (expressed in the ECEF frame).

Definition: FGAccelerations.h:340

JSBSim::FGAccelerations::Inputs::Tec2b

FGMatrix33 Tec2b

Transformation matrix from the ECEF to the Body frame.

Definition: FGAccelerations.h:328

JSBSim::FGAccelerations::Inputs::Mass

double Mass

Body mass.

Definition: FGAccelerations.h:358

◆ InitializeDerivatives()

void InitializeDerivatives ( void )

Initializes the FGAccelerations class prior to a new execution.

Initializes the class prior to a new execution when the input data stored in the Inputs structure have been set to their initial values.

Definition at line 334 of file FGAccelerations.cpp.

 {
   // Make an initial run and set past values
   CalculatePQRdot();           // Angular rate derivative
   CalculateUVWdot();           // Translational rate derivative
   CalculateFrictionForces(0.);   // Update rate derivatives with friction forces
 }

◆ InitModel()

bool InitModel ( void )

overridevirtual

Initializes the FGAccelerations class after instantiation and prior to first execution.

The base class FGModel::InitModel is called first, initializing pointers to the other FGModel objects (and others).

Reimplemented from FGModelFunctions.

Definition at line 92 of file FGAccelerations.cpp.

 {
   if (!FGModel::InitModel()) return false;
  
   vPQRidot.InitMatrix();
   vUVWidot.InitMatrix();
   vUVWdot.InitMatrix();
   vBodyAccel.InitMatrix();
  
   return true;
 }

◆ Run()

bool Run ( bool Holding )

overridevirtual

Runs the state propagation model; called by the Executive Can pass in a value indicating if the executive is directing the simulation to Hold.

Parameters

Holding if true, the executive has been directed to hold the sim from advancing time. Some models may ignore this flag, such as the Input model, which may need to be active to listen on a socket for the "Resume" command to be given.

Returns: false if no error

Reimplemented from FGModel.

Definition at line 109 of file FGAccelerations.cpp.

 {
   if (FGModel::Run(Holding)) return true;  // Fast return if we have nothing to do ...
   if (Holding) return false;
  
   CalculatePQRdot();   // Angular rate derivative
   CalculateUVWdot();   // Translational rate derivative
  
   if (!FDMExec->GetHoldDown())
     CalculateFrictionForces(in.DeltaT * rate);  // Update rate derivatives with friction forces
  
   Debug(2);
   return false;
 }

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◆ SetHoldDown()

void SetHoldDown ( bool hd )

Sets the property forces/hold-down.

This allows to do hard 'hold-down' such as for rockets on a launch pad with engines ignited.

Parameters

hd	enables the 'hold-down' function if non-zero

Definition at line 209 of file FGAccelerations.cpp.

 {
   if (hd) {
     vUVWidot = in.vOmegaPlanet * (in.vOmegaPlanet * in.vInertialPosition);
     vUVWdot.InitMatrix();
     vPQRidot = in.vPQRi * (in.Ti2b * in.vOmegaPlanet);
     vPQRdot.InitMatrix();
   }
 }

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

Detailed Description

Classes

Public Member Functions

Public Attributes

Additional Inherited Members

Constructor & Destructor Documentation

◆ FGAccelerations()

Member Function Documentation

◆ GetBodyAccel() [1/2]

◆ GetBodyAccel() [2/2]

◆ GetForces()

◆ GetGroundForces()

◆ GetGroundMoments()

◆ GetMoments()

◆ GetPQRdot() [1/2]

◆ GetPQRdot() [2/2]

◆ GetPQRidot()

◆ GetUVWdot() [1/2]

◆ GetUVWdot() [2/2]

◆ GetUVWidot()

◆ GetWeight()

◆ InitializeDerivatives()

◆ InitModel()

◆ Run()

◆ SetHoldDown()