FlightGear: JSBSim::FGBuoyantForces Class Reference

Encapsulates the Buoyant forces calculations. More...

#include <FGBuoyantForces.h>

Public Member Functions
	FGBuoyantForces (FGFDMExec *Executive)
	Constructor.

	~FGBuoyantForces () override
	Destructor.

bool	InitModel (void) override

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

bool	Load (Element *element) override
	Loads the Buoyant forces model.

const FGColumnVector3 &	GetForces (void) const
	Gets the total Buoyant force vector.

double	GetForces (int idx) const
	Gets a component of the total Buoyant force vector.

const FGColumnVector3 &	GetMoments (void) const
	Gets the total Buoyancy moment vector.

double	GetMoments (int idx) const
	Gets a component of the total Buoyancy moment vector.

double	GetGasMass (void) const
	Gets the total gas mass.

const FGColumnVector3 &	GetGasMassMoment (void)
	Gets the total moment from the gas mass.

const FGMatrix33 &	GetGasMassInertia (void)
	Gets the total moments of inertia for the gas mass in the body frame.

std::string	GetBuoyancyStrings (const std::string &delimeter)
	Gets the strings for the current set of gas cells.

std::string	GetBuoyancyValues (const std::string &delimeter)
	Gets the coefficient values.

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

	~FGModel () override
	Destructor.

bool	InitModel (void) override

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

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

FGFDMExec *	GetExec (void)

void	SetPropertyManager (FGPropertyManager *fgpm)

virtual SGPath	FindFullPathName (const SGPath &path) const

const std::string &	GetName (void)

Public Member Functions inherited from JSBSim::FGModelFunctions
virtual	~FGModelFunctions ()

void	RunPreFunctions (void)

void	RunPostFunctions (void)

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

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

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

std::string	GetFunctionStrings (const std::string &delimeter) const
	Gets the strings for the current set of functions.

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

FGFunction *	GetPreFunction (const std::string &name)
	Get one of the "pre" function.

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

virtual	~FGJSBBase ()
	Destructor for FGJSBBase.

void	PutMessage (const Message &msg)
	Places a Message structure on the Message queue.

void	PutMessage (const std::string &text)
	Creates a message with the given text and places it on the queue.

void	PutMessage (const std::string &text, bool bVal)
	Creates a message with the given text and boolean value and places it on the queue.

void	PutMessage (const std::string &text, int iVal)
	Creates a message with the given text and integer value and places it on the queue.

void	PutMessage (const std::string &text, double dVal)
	Creates a message with the given text and double value and places it on the queue.

int	SomeMessages (void) const
	Reads the message on the queue (but does not delete it).

void	ProcessMessage (void)
	Reads the message on the queue and removes it from the queue.

Message *	ProcessNextMessage (void)
	Reads the next message on the queue and removes it from the queue.

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

Public Attributes
FGGasCell::Inputs	in

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

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

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

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

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

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

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

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

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

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

static const std::string &	GetVersion (void)
	Returns the version number of JSBSim.

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

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

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

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

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

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

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

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

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

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

static double	PitotTotalPressure (double mach, double p)
	Compute the total pressure in front of the Pitot tube.

static double	MachFromImpactPressure (double qc, double p)
	Compute the Mach number from the differential pressure (qc) and the static pressure.

static double	VcalibratedFromMach (double mach, double p)
	Calculate the calibrated airspeed from the Mach number.

static double	MachFromVcalibrated (double vcas, double p)
	Calculate the Mach number from the calibrated airspeed.Based on the formulas in the US Air Force Aircraft Performance Flight Testing Manual (AFFTC-TIH-99-01).

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

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

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

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

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 double	GaussianRandomNumber (void)

Static Public Attributes inherited from JSBSim::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 JSBSim::FGModel
bool	Upload (Element *el, bool preLoad)
	Uploads this model in memory.

static std::string	CreateIndexedPropertyName (const std::string &Property, int index)

Protected Attributes inherited from JSBSim::FGModel
unsigned int	exe_ctr

unsigned int	rate

std::string	Name

FGFDMExec *	FDMExec

FGPropertyManager *	PropertyManager

Protected Attributes inherited from JSBSim::FGModelFunctions
std::vector< FGFunction * >	PreFunctions

std::vector< FGFunction * >	PostFunctions

FGPropertyReader	LocalProperties

static Message	localMsg

static std::queue< Message >	Messages

static unsigned int	messageId = 0

static constexpr double	radtodeg = 180. / 3.14159265358979323846

static constexpr double	degtorad = 3.14159265358979323846 / 180.

static constexpr double	hptoftlbssec = 550.0

static constexpr double	psftoinhg = 0.014138

static constexpr double	psftopa = 47.88

static constexpr double	ktstofps = 1.68781

static constexpr double	fpstokts = 1.0 / ktstofps

static constexpr double	inchtoft = 1.0/12.0

static constexpr double	fttom = 0.3048

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.

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__

static int	gaussian_random_number_phase = 0

Detailed Description

Encapsulates the Buoyant forces calculations.

This class owns and contains the list of force/coefficients that define the Buoyant properties of an air vehicle.

Here's an example of a gas cell specification:

<buoyant_forces>
 
  <!-- Interface properties -->
  <property>ballonets/in-flow-ft3ps[0]</property>
 
  <gas_cell type="HYDROGEN">
    <location unit="M">
      <x> 18.8 </x>
      <y> 0.0 </y>
      <z> 0.0 </z>
    </location>
    <x_radius unit="M"> 22.86 </x_radius>
    <y_radius unit="M">  4.55 </y_radius>
    <z_radius unit="M">  4.55 </z_radius>
    <max_overpressure unit="PA"> 340.0 </max_overpressure> 
    <valve_coefficient unit="M4*SEC/KG"> 0.015 </valve_coefficient>
  </gas_cell>
  
  ... {other gas cells} ...
  
</buoyant_forces>

See FGGasCell for the full configuration file format for gas cells.

Author: Anders Gidenstam, Jon S. Berndt

Definition at line 98 of file FGBuoyantForces.h.

Constructor & Destructor Documentation

◆ FGBuoyantForces()

JSBSim::FGBuoyantForces::FGBuoyantForces ( FGFDMExec * Executive )

Constructor.

Parameters

Executive a pointer to the parent executive object

Definition at line 51 of file FGBuoyantForces.cpp.

◆ ~FGBuoyantForces()

JSBSim::FGBuoyantForces::~FGBuoyantForces ( )

override

Destructor.

Definition at line 67 of file FGBuoyantForces.cpp.

Member Function Documentation

◆ GetBuoyancyStrings()

string JSBSim::FGBuoyantForces::GetBuoyancyStrings ( const std::string & delimeter )

Gets the strings for the current set of gas cells.

Parameters

delimeter either a tab or comma string depending on output type

Returns: a string containing the descriptive names for all parameters

Definition at line 182 of file FGBuoyantForces.cpp.

◆ GetBuoyancyValues()

string JSBSim::FGBuoyantForces::GetBuoyancyValues ( const std::string & delimeter )

Gets the coefficient values.

Parameters

delimeter either a tab or comma string depending on output type

Returns: a string containing the numeric values for the current set of parameters

Definition at line 212 of file FGBuoyantForces.cpp.

◆ GetForces() [1/2]

double JSBSim::FGBuoyantForces::GetForces ( int idx ) const

inline

Gets a component of the total Buoyant force vector.

Returns: a component of the force vector in lbs.

Definition at line 132 of file FGBuoyantForces.h.

◆ GetForces() [2/2]

const FGColumnVector3 & JSBSim::FGBuoyantForces::GetForces ( void ) const

inline

Gets the total Buoyant force vector.

Returns: a force vector in lbs.

Definition at line 128 of file FGBuoyantForces.h.

◆ GetGasMass()

double JSBSim::FGBuoyantForces::GetGasMass ( void ) const

Gets the total gas mass.

The gas mass is part of the aircraft's inertia.

Returns: mass in slugs.

Definition at line 141 of file FGBuoyantForces.cpp.

◆ GetGasMassInertia()

const FGMatrix33 & JSBSim::FGBuoyantForces::GetGasMassInertia ( void )

Gets the total moments of inertia for the gas mass in the body frame.

Returns: moments of inertia matrix in the body frame in slug ft².

Definition at line 165 of file FGBuoyantForces.cpp.

◆ GetGasMassMoment()

const FGColumnVector3 & JSBSim::FGBuoyantForces::GetGasMassMoment ( void )

Gets the total moment from the gas mass.

Returns: a moment vector in the structural frame in lbs in.

Definition at line 154 of file FGBuoyantForces.cpp.

◆ GetMoments() [1/2]

double JSBSim::FGBuoyantForces::GetMoments ( int idx ) const

inline

Gets a component of the total Buoyancy moment vector.

Returns: a component of the moment vector in the body frame in lbs ft.

Definition at line 140 of file FGBuoyantForces.h.

◆ GetMoments() [2/2]

const FGColumnVector3 & JSBSim::FGBuoyantForces::GetMoments ( void ) const

inline

Gets the total Buoyancy moment vector.

Returns: a moment vector in the body frame in lbs ft.

Definition at line 136 of file FGBuoyantForces.h.

◆ InitModel()

bool JSBSim::FGBuoyantForces::InitModel ( void )

overridevirtual

Reimplemented from JSBSim::FGModelFunctions.

Definition at line 77 of file FGBuoyantForces.cpp.

◆ Load()

bool JSBSim::FGBuoyantForces::Load ( Element * element )

overridevirtual

Loads the Buoyant forces model.

The Load function for this class expects the XML parser to have found the Buoyant_forces keyword in the configuration file.

Parameters

element pointer to the current XML element for Buoyant forces parameters.

Returns: true if successful

Reimplemented from JSBSim::FGModel.

Definition at line 113 of file FGBuoyantForces.cpp.

◆ Run()

bool JSBSim::FGBuoyantForces::Run ( bool Holding )

overridevirtual

Runs the Buoyant forces 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 JSBSim::FGModel.

Definition at line 89 of file FGBuoyantForces.cpp.

Member Data Documentation

◆ in

FGGasCell::Inputs JSBSim::FGBuoyantForces::in

Definition at line 167 of file FGBuoyantForces.h.

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

Public Member Functions

Public Attributes

Additional Inherited Members

Detailed Description

Constructor & Destructor Documentation

◆ FGBuoyantForces()

◆ ~FGBuoyantForces()

Member Function Documentation

◆ GetBuoyancyStrings()

◆ GetBuoyancyValues()

◆ GetForces() [1/2]

◆ GetForces() [2/2]

◆ GetGasMass()

◆ GetGasMassInertia()

◆ GetGasMassMoment()

◆ GetMoments() [1/2]

◆ GetMoments() [2/2]

◆ InitModel()

◆ Load()

◆ Run()

Member Data Documentation

◆ in