FlightGear: JSBSim::FGRocket Class Reference

Models a generic rocket engine. More...

#include <FGRocket.h>

Public Member Functions
	FGRocket (FGFDMExec exec, Element el, int engine_number, struct FGEngine::Inputs &input)
	Constructor.

	~FGRocket (void)
	Destructor.

void	Calculate (void)
	Determines the thrust.

double	CalcFuelNeed (void)
	The fuel need is calculated based on power levels and flow rate for that power level.

double	CalcOxidizerNeed (void)
	The oxidizer need is calculated based on power levels and flow rate for that power level.

double	GetTotalImpulse (void) const
	Gets the total impulse of the rocket.

double	GetVacTotalImpulse (void) const
	Gets the total impulse of the rocket.

bool	GetFlameout (void)
	Gets the flame-out status.

double	GetOxiFlowRate (void) const

double	GetMixtureRatio (void) const

double	GetIsp (void) const

void	SetMixtureRatio (double mix)

void	SetIsp (double isp)

std::string	GetEngineLabels (const std::string &delimiter)

std::string	GetEngineValues (const std::string &delimiter)

void	SetThrustVariation (double var)
	Sets the thrust variation for a solid rocket engine.

void	SetTotalIspVariation (double var)
	Sets the variation in total motor energy.

double	GetThrustVariation (void) const
	Returns the thrust variation, if any.

double	GetTotalIspVariation (void) const
	Returns the Total Isp variation, if any.

Public Member Functions inherited from JSBSim::FGEngine
	FGEngine (int engine_number, struct Inputs &input)

	~FGEngine () override

EngineType	GetType (void) const

virtual const std::string &	GetName (void) const

virtual double	GetThrottleMin (void) const

virtual double	GetThrottleMax (void) const

virtual bool	GetStarter (void) const

virtual double	getFuelFlow_gph () const

virtual double	getFuelFlow_pph () const

virtual double	GetFuelFlowRate (void) const

virtual double	GetFuelFlowRateGPH (void) const

virtual double	GetFuelUsedLbs (void) const

virtual bool	GetStarved (void) const

virtual bool	GetRunning (void) const

virtual bool	GetCranking (void) const

virtual void	SetStarved (bool tt)

virtual void	SetStarved (void)

virtual void	SetRunning (bool bb)

virtual void	SetName (const std::string &name)

virtual void	SetFuelFreeze (bool f)

virtual void	SetFuelDensity (double d)

virtual void	SetStarter (bool s)

virtual int	InitRunning (void)

virtual void	ResetToIC (void)
	Resets the Engine parameters to the initial conditions.

virtual double	GetThrust (void) const

virtual double	GetPowerAvailable (void)

virtual const FGColumnVector3 &	GetBodyForces (void)

virtual const FGColumnVector3 &	GetMoments (void)

void	LoadThruster (FGFDMExec exec, Element el)

FGThruster *	GetThruster (void) const

unsigned int	GetSourceTank (unsigned int i) const

size_t	GetNumSourceTanks () const

void	LoadThrusterInputs ()

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.

Additional Inherited Members
Public Types inherited from JSBSim::FGEngine
enum	EngineType { etUnknown , etRocket , etPiston , etTurbine , etTurboprop , etElectric }

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)

Public Attributes inherited from JSBSim::FGEngine
struct Inputs &	in

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::FGEngine
bool	Load (FGFDMExec exec, Element el)

void	Debug (int from)

Protected Member Functions inherited from JSBSim::FGModelFunctions
virtual bool	InitModel (void)

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

Protected Attributes inherited from JSBSim::FGEngine
std::string	Name

const int	EngineNumber

EngineType	Type

double	SLFuelFlowMax

double	MaxThrottle

double	MinThrottle

double	FuelExpended

double	FuelFlowRate

double	PctPower

bool	Starter

bool	Starved

bool	Running

bool	Cranking

bool	FuelFreeze

double	FuelFlow_gph

double	FuelFlow_pph

double	FuelUsedLbs

double	FuelDensity

FGThruster *	Thruster

std::vector< int >	SourceTanks

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

Models a generic rocket engine.

The rocket engine is modeled given the following parameters:

Specific Impulse (in sec)

Additionally, the following control inputs, operating characteristics, and location are required, as with all other engine types:

Throttle setting (in percent, from 0 to 1.0)
Maximum allowable throttle setting
Minimum working throttle setting
Sea level fuel flow at maximum thrust
Sea level oxidizer flow at maximum thrust
X, Y, Z location in structural coordinate frame
Pitch and Yaw

The nozzle exit pressure (p2) is returned via a call to FGNozzle::GetPowerRequired(). This exit pressure is used to get the at-altitude thrust level.

One can model the thrust of a solid rocket by providing a normalized thrust table as a function of time. For instance, the space shuttle solid rocket booster normalized thrust value looks roughly like this:

    
 <thrust_table name="propulsion/thrust_time" type="internal">
   <tableData>
      0.0   0.00
      0.2   0.91
      8.0   0.97
     16.0   0.99
     20.0   1.00
     21.0   1.00
     24.0   0.95
     32.0   0.85
     40.0   0.78
     48.0   0.72
     50.0   0.71
     52.0   0.71
     56.0   0.73
     64.0   0.78
     72.0   0.82
     80.0   0.81
     88.0   0.73
     96.0   0.69
    104.0   0.59
    112.0   0.46
    120.0   0.09
    132.0   0.00
   </tableData>
 </thrust_table>

The left column is time, the right column is normalized thrust. Inside the FGRocket class code, the maximum thrust is calculated, and multiplied by this table. The Rocket class also tracks burn time. All that needs to be done is for the rocket engine to be throttle up to 1. At that time, the solid rocket fuel begins burning and thrust is provided.

@author Jon S. Berndt
@see FGNozzle,
FGThruster,
FGForce,
FGEngine,

Definition at line 125 of file FGRocket.h.

Constructor & Destructor Documentation

◆ FGRocket()

JSBSim::FGRocket::FGRocket	(	FGFDMExec *	exec,
		Element *	el,
		int	engine_number,
		struct FGEngine::Inputs &	input )

Constructor.

Parameters

exec	pointer to JSBSim parent object, the FDM Executive.
el	a pointer to the XML Element instance representing the engine.
engine_number	engine number

Definition at line 54 of file FGRocket.cpp.

◆ ~FGRocket()

JSBSim::FGRocket::~FGRocket ( void )

Destructor.

Definition at line 148 of file FGRocket.cpp.

Member Function Documentation

◆ CalcFuelNeed()

double JSBSim::FGRocket::CalcFuelNeed ( void )

virtual

The fuel need is calculated based on power levels and flow rate for that power level.

It is also turned from a rate into an actual amount (pounds) by multiplying it by the delta T and the rate.

Returns: Total fuel requirement for this engine in pounds.

Reimplemented from JSBSim::FGEngine.

Definition at line 222 of file FGRocket.cpp.

◆ CalcOxidizerNeed()

double JSBSim::FGRocket::CalcOxidizerNeed ( void )

virtual

The oxidizer need is calculated based on power levels and flow rate for that power level.

It is also turned from a rate into an actual amount (pounds) by multiplying it by the delta T and the rate.

Returns: Total oxidizer requirement for this engine in pounds.

Reimplemented from JSBSim::FGEngine.

Definition at line 238 of file FGRocket.cpp.

◆ Calculate()

void JSBSim::FGRocket::Calculate ( void )

virtual

Determines the thrust.

Implements JSBSim::FGEngine.

Definition at line 156 of file FGRocket.cpp.

◆ GetEngineLabels()

string JSBSim::FGRocket::GetEngineLabels ( const std::string & delimiter )

virtual

Implements JSBSim::FGEngine.

Definition at line 248 of file FGRocket.cpp.

◆ GetEngineValues()

string JSBSim::FGRocket::GetEngineValues ( const std::string & delimiter )

virtual

Implements JSBSim::FGEngine.

Definition at line 267 of file FGRocket.cpp.

◆ GetFlameout()

bool JSBSim::FGRocket::GetFlameout ( void )

inline

Gets the flame-out status.

The engine will "flame out" if the throttle is set below the minimum sustainable-thrust setting.

Returns: true if engine has flamed out.

Definition at line 164 of file FGRocket.h.

◆ GetIsp()

double JSBSim::FGRocket::GetIsp ( void ) const

inline

Definition at line 170 of file FGRocket.h.

◆ GetMixtureRatio()

double JSBSim::FGRocket::GetMixtureRatio ( void ) const

inline

Definition at line 168 of file FGRocket.h.

◆ GetOxiFlowRate()

double JSBSim::FGRocket::GetOxiFlowRate ( void ) const

inline

Definition at line 166 of file FGRocket.h.

◆ GetThrustVariation()

double JSBSim::FGRocket::GetThrustVariation ( void ) const

inline

Returns the thrust variation, if any.

Definition at line 200 of file FGRocket.h.

◆ GetTotalImpulse()

double JSBSim::FGRocket::GetTotalImpulse ( void ) const

inline

Gets the total impulse of the rocket.

Returns: The cumulative actual total impulse of the rocket up to this time.

Definition at line 154 of file FGRocket.h.

◆ GetTotalIspVariation()

double JSBSim::FGRocket::GetTotalIspVariation ( void ) const

inline

Returns the Total Isp variation, if any.

Definition at line 203 of file FGRocket.h.

◆ GetVacTotalImpulse()

double JSBSim::FGRocket::GetVacTotalImpulse ( void ) const

inline

Gets the total impulse of the rocket.

Returns: The cumulative vacuum total impulse of the rocket up to this time.

Definition at line 158 of file FGRocket.h.

◆ SetIsp()

void JSBSim::FGRocket::SetIsp ( double isp )

inline

Definition at line 174 of file FGRocket.h.

◆ SetMixtureRatio()

void JSBSim::FGRocket::SetMixtureRatio ( double mix )

inline

Definition at line 172 of file FGRocket.h.

◆ SetThrustVariation()

void JSBSim::FGRocket::SetThrustVariation ( double var )

inline

Sets the thrust variation for a solid rocket engine.

Solid propellant rocket motor thrust characteristics are typically defined at 70 degrees F temperature. At any other temperature, performance will be different. Warmer propellant grain will burn quicker and at higher thrust. Total motor impulse is not changed for change in thrust.

Parameters

var	the variation in percent. That is, a 2 percent variation would be specified as 0.02. A positive 2% variation in thrust would increase the thrust by 2%, and shorten the burn time.

Definition at line 188 of file FGRocket.h.

◆ SetTotalIspVariation()

void JSBSim::FGRocket::SetTotalIspVariation ( double var )

inline

Sets the variation in total motor energy.

The total energy present in a solid rocket motor can be modified (such as might happen with manufacturing variations) by setting the total Isp variation.

Parameters

var	the variation in percent. That is, a 2 percent variation would be specified as 0.02. This variation will affect the total thrust, but not the burn time.

Definition at line 197 of file FGRocket.h.

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

Public Member Functions

Additional Inherited Members

Detailed Description

Constructor & Destructor Documentation

◆ FGRocket()

◆ ~FGRocket()

Member Function Documentation

◆ CalcFuelNeed()

◆ CalcOxidizerNeed()

◆ Calculate()

◆ GetEngineLabels()

◆ GetEngineValues()

◆ GetFlameout()

◆ GetIsp()

◆ GetMixtureRatio()

◆ GetOxiFlowRate()

◆ GetThrustVariation()

◆ GetTotalImpulse()

◆ GetTotalIspVariation()

◆ GetVacTotalImpulse()

◆ SetIsp()

◆ SetMixtureRatio()

◆ SetThrustVariation()

◆ SetTotalIspVariation()