FGRocket Class Reference

#include <FGRocket.h>

Inherits FGEngine.

List of all members.

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Detailed Description

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

Id

FGRocket.h,v 1.7 2008/11/17 12:21:07 jberndt Exp

See also:

FGNozzle, FGThruster, FGForce, FGEngine, FGPropulsion, FGTank

Definition at line 134 of file FGRocket.h.

Public Member Functions
double	Calculate (void)
	Determines the thrust.
	FGRocket (FGFDMExec *exec, Element *el, int engine_number)
	Constructor.
string	GetEngineLabels (string delimeter)
string	GetEngineValues (string delimeter)
bool	GetFlameout (void)
	Gets the flame-out status.
double	GetOxiFlowRate (void) const
double	GetTotalImpulse (void) const
	Gets the total impulse of the rocket.
	~FGRocket (void)
	Destructor.

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Constructor & Destructor Documentation

FGRocket	(	FGFDMExec *	exec,
		Element *	el,
		int	engine_number
	)

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.

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Member Function Documentation

double Calculate

(

void

)

[virtual]

Returns:

thrust

Reimplemented from FGEngine.

Definition at line 107 of file FGRocket.cpp.

bool GetFlameout

(

void

)

[inline]

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 158 of file FGRocket.h.

double GetTotalImpulse

(

void

)

const [inline]

Returns:

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

Definition at line 152 of file FGRocket.h.

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

• FGRocket.h
• FGRocket.cpp