Author: Jon S. Berndt
Date started: 09/12/2000
- ------------- Copyright (C) 2000 Jon S. Berndt (jsb@hal-pc.org) --------------
+ ------------- Copyright (C) 2000 Jon S. Berndt (jon@jsbsim.org) --------------
This program is free software; you can redistribute it and/or modify it under
the terms of the GNU Lesser General Public License as published by the Free Software
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/
#include "FGEngine.h"
-#include <math/FGTable.h>
-#include <input_output/FGXMLElement.h>
+#include "math/FGTable.h"
+#include "input_output/FGXMLElement.h"
/*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
DEFINITIONS
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/
-#define ID_ROCKET "$Id$"
+#define ID_ROCKET "$Id: FGRocket.h,v 1.14 2010/08/21 18:08:25 jberndt Exp $"
/*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
FORWARD DECLARATIONS
/** Models a generic rocket engine.
The rocket engine is modeled given the following parameters:
<ul>
- <li>Chamber pressure (in psf)</li>
- <li>Specific heat ratio (usually about 1.2 for hydrocarbon fuel and LOX)</li>
- <li>Propulsive efficiency (in percent, from 0 to 1.0)</li>
- <li>Variance (in percent, from 0 to 1.0, nominally 0.05)</li>
+ <li>Specific Impulse (in sec)</li>
</ul>
Additionally, the following control inputs, operating characteristics, and
location are required, as with all other engine types:
<li>Pitch and Yaw</li>
</ul>
The nozzle exit pressure (p2) is returned via a
- call to FGNozzle::GetPowerRequired(). This exit pressure is used,
- along with chamber pressure and specific heat ratio, to get the
- thrust coefficient for the throttle setting. This thrust
- coefficient is multiplied by the chamber pressure and then passed
- to the nozzle Calculate() routine, where the thrust force is
- determined.
+ 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
fuel begins burning and thrust is provided.
@author Jon S. Berndt
- $Id$
+ $Id: FGRocket.h,v 1.14 2010/08/21 18:08:25 jberndt Exp $
@see FGNozzle,
FGThruster,
FGForce,
/** Destructor */
~FGRocket(void);
- /** Determines the thrust coefficient.
- @return thrust coefficient times chamber pressure */
- double Calculate(void);
+ /** Determines the thrust.*/
+ void Calculate(void);
- /** Gets the chamber pressure.
- @return chamber pressure in psf. */
- double GetChamberPressure(void) {return PC;}
+ /** Gets the total impulse of the rocket.
+ @return The cumulative total impulse of the rocket up to this time.*/
+ double GetTotalImpulse(void) const {return It;}
/** Gets the flame-out status.
The engine will "flame out" if the throttle is set below the minimum
- sustainable setting.
+ sustainable-thrust setting.
@return true if engine has flamed out. */
bool GetFlameout(void) {return Flameout;}
- string GetEngineLabels(string delimeter);
- string GetEngineValues(string delimeter);
+
+ double GetOxiFlowRate(void) const {return OxidizerFlowRate;}
+
+ std::string GetEngineLabels(const std::string& delimiter);
+ std::string GetEngineValues(const std::string& delimiter);
+
+ /** 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.
+ @param 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. */
+ void SetThrustVariation(double var) {ThrustVariation = var;}
+
+ /** 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.
+ @param 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.*/
+ void SetTotalIspVariation(double var) {TotalIspVariation = var;}
+
+ /** Returns the thrust variation, if any. */
+ double GetThrustVariation(void) const {return ThrustVariation;}
+
+ /** Returns the Total Isp variation, if any. */
+ double GetTotalIspVariation(void) const {return TotalIspVariation;}
private:
- double SHR;
- double maxPC;
- double propEff;
- double kFactor;
- double Variance;
- double PC;
+ /** Reduces the fuel in the active tanks by the amount required.
+ This function should be called from within the
+ derived class' Calculate() function before any other calculations are
+ done. This base class method removes fuel from the fuel tanks as
+ appropriate, and sets the starved flag if necessary. */
+ void ConsumeFuel(void);
+
+ /** 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.
+ @return Total fuel requirement for this engine in pounds. */
+ double CalcFuelNeed(void);
+
+ /** 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.
+ @return Total oxidizer requirement for this engine in pounds. */
+ double CalcOxidizerNeed(void);
+
+ /** Returns the vacuum thrust.
+ @return The vacuum thrust in lbs. */
+ double GetVacThrust(void) const {return VacThrust;}
+
+ void bindmodel(void);
+
+ double Isp; // Vacuum Isp
+ double It;
+ double MxR; // Mixture Ratio
double BurnTime;
+ double ThrustVariation;
+ double TotalIspVariation;
+ double VacThrust;
+ double previousFuelNeedPerTank;
+ double previousOxiNeedPerTank;
+ double OxidizerExpended;
+ double SLOxiFlowMax;
+ double OxidizerFlowRate;
+ double PropellantFlowRate;
bool Flameout;
+ double BuildupTime;
FGTable* ThrustTable;
void Debug(int from);
projects / flightgear.git / blobdiff