09/12/2000 JSB Created
10/01/2001 DPM Modified to use equations from Dave Luff's piston model.
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-COMMENTS, REFERENCES, and NOTES
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SENTRY
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#include "FGEngine.h"
#include "FGConfigFile.h"
+#include "FGTable.h"
/*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
DEFINITIONS
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#define ID_PISTON "$Id$";
+#define FG_MAX_BOOST_SPEEDS 3
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FORWARD DECLARATIONS
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-/*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
-COMMENTS, REFERENCES, and NOTES
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+namespace JSBSim {
/*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
-DOCUMENTATION
+CLASS DOCUMENTATION
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-/** Models Dave Luff's engine model as ported into JSBSim by David Megginson.
+/** Models Dave Luff's Turbo/Supercharged Piston engine model.
+ Additional elements are required for a supercharged engine. These can be
+ left off a non-supercharged engine, ie. the changes are all backward
+ compatible at present.
+
+ - NUMBOOSTSPEEDS - zero (or not present) for a naturally-aspirated engine,
+ either 1, 2 or 3 for a boosted engine. This corresponds to the number of
+ supercharger speeds. Merlin XII had 1 speed, Merlin 61 had 2, a late
+ Griffon engine apparently had 3. No known engine more than 3, although
+ some German engines apparently had a continuously variable-speed
+ supercharger.
+
+ - BOOSTOVERRIDE - whether the boost pressure control system (either a boost
+ control valve for superchargers or wastegate for turbochargers) can be
+ overriden by the pilot. During wartime this was commonly possible, and
+ known as "War Emergency Power" by the Brits. 1 or 0 in the config file.
+ This isn't implemented in the model yet though, there would need to be
+ some way of getting the boost control cutout lever position (on or off)
+ from FlightGear first.
+
+ - The next items are all appended with either 1, 2 or 3 depending on which
+ boost speed they refer to, eg RATEDBOOST1. The rated values seems to have
+ been a common convention at the time to express the maximum continuously
+ available power, and the conditions to attain that power.
+
+ - RATEDBOOST[123] - the absolute rated boost above sea level ambient for a
+ given boost speed, in psi. Eg the Merlin XII had a rated boost of 9psi,
+ giving approximately 42inHg manifold pressure up to the rated altitude.
+
+ - RATEDALTITUDE[123] - The altitude up to which rated boost can be
+ maintained. Up to this altitude the boost is maintained constant for a
+ given throttle position by the BCV or wastegate. Beyond this altitude the
+ manifold pressure must drop, since the supercharger is now at maximum
+ unregulated output. The actual pressure multiplier of the supercharger
+ system is calculated at initialisation from this value.
+
+ - RATEDPOWER[123] - The power developed at rated boost at rated altitude at
+ rated rpm.
+
+ - RATEDRPM[123] - The rpm at which rated power is developed.
+
+ - TAKEOFFBOOST - Takeoff boost in psi above ambient. Many aircraft had an
+ extra boost setting beyond rated boost, but not totally uncontrolled as in
+ the already mentioned boost-control-cutout, typically attained by pushing
+ the throttle past a mechanical 'gate' preventing its inadvertant use. This
+ was typically used for takeoff, and emergency situations, generally for
+ not more than five minutes. This is a change in the boost control
+ setting, not the actual supercharger speed, and so would only give extra
+ power below the rated altitude. When TAKEOFFBOOST is specified in the
+ config file (and is above RATEDBOOST1), then the throttle position is
+ interpreted as:
+
+ - 0 to 0.95 : idle manifold pressure to rated boost (where attainable)
+ - 0.96, 0.97, 0.98 : rated boost (where attainable).
+ - 0.99, 1.0 : takeoff boost (where attainable).
+
+ A typical takeoff boost for an earlyish Merlin was about 12psi, compared
+ with a rated boost of 9psi.
+
+ It is quite possible that other boost control settings could have been used
+ on some aircraft, or that takeoff/extra boost could have activated by other
+ means than pushing the throttle full forward through a gate, but this will
+ suffice for now.
+
+ Note that MAXMP is still the non-boosted max manifold pressure even for
+ boosted engines - effectively this is simply a measure of the pressure drop
+ through the fully open throttle.
+
@author Jon S. Berndt (Engine framework code and framework-related mods)
@author Dave Luff (engine operational code)
- @author David Megginson (porting and additional code)
+ @author David Megginson (initial porting and additional code)
@version $Id$
*/
{
public:
/// Constructor
- FGPiston(FGFDMExec* exec, FGConfigFile* Eng_cfg);
+ FGPiston(FGFDMExec* exec, FGConfigFile* Eng_cfg, int engine_number);
/// Destructor
~FGPiston();
- float Calculate(float PowerRequired);
- float GetPowerAvailable(void) {return PowerAvailable;}
+ string GetEngineLabels(string delimeter);
+ string GetEngineValues(string delimeter);
+
+ double Calculate(void);
+ double GetPowerAvailable(void) {return PowerAvailable;}
+ double CalcFuelNeed(void);
+
+ void SetMagnetos(int magnetos) {Magnetos = magnetos;}
+
+ double GetEGT(void) { return EGT_degC; }
+ int GetMagnetos(void) {return Magnetos;}
+
+ double getExhaustGasTemp_degF(void) {return KelvinToFahrenheit(ExhaustGasTemp_degK);}
+ double getManifoldPressure_inHg(void) const {return ManifoldPressure_inHg;}
+ double getCylinderHeadTemp_degF(void) {return KelvinToFahrenheit(CylinderHeadTemp_degK);}
+ double getOilPressure_psi(void) const {return OilPressure_psi;}
+ double getOilTemp_degF (void) {return KelvinToFahrenheit(OilTemp_degK);}
+ double getRPM(void) {return RPM;}
private:
- float BrakeHorsePower;
- float SpeedSlope;
- float SpeedIntercept;
- float AltitudeSlope;
- float PowerAvailable;
+ int crank_counter;
- // timestep
- float dt;
+ double BrakeHorsePower;
+ double SpeedSlope;
+ double SpeedIntercept;
+ double AltitudeSlope;
+ double PowerAvailable;
- // engine state
- bool running;
- bool cranking;
+ // timestep
+ double dt;
void doEngineStartup(void);
- void doManifoldPressure(void);
+ void doBoostControl(void);
+ void doMAP(void);
void doAirFlow(void);
void doFuelFlow(void);
void doEnginePower(void);
//
// constants
//
- const float CONVERT_CUBIC_INCHES_TO_METERS_CUBED;
- const float R_air;
- const float rho_fuel; // kg/m^3
- const float calorific_value_fuel; // W/Kg (approximate)
- const float Cp_air; // J/KgK
- const float Cp_fuel; // J/KgK
+ const double R_air;
+ const double rho_fuel; // kg/m^3
+ const double calorific_value_fuel; // W/Kg (approximate)
+ const double Cp_air; // J/KgK
+ const double Cp_fuel; // J/KgK
+
+ FGTable *Lookup_Combustion_Efficiency;
+ FGTable *Power_Mixture_Correlation;
//
// Configuration
//
- float MinManifoldPressure_inHg; // Inches Hg
- float MaxManifoldPressure_inHg; // Inches Hg
- float Displacement; // cubic inches
- float MaxHP; // horsepower
- float Cycles; // cycles/power stroke
- float IdleRPM; // revolutions per minute
+ double MinManifoldPressure_inHg; // Inches Hg
+ double MaxManifoldPressure_inHg; // Inches Hg
+ double Displacement; // cubic inches
+ double MaxHP; // horsepower
+ double Cycles; // cycles/power stroke
+ double IdleRPM; // revolutions per minute
+ int BoostSpeeds; // Number of super/turbocharger boost speeds - zero implies no turbo/supercharging.
+ int BoostSpeed; // The current boost-speed (zero-based).
+ bool Boosted; // Set true for boosted engine.
+ int BoostOverride; // The raw value read in from the config file - should be 1 or 0 - see description below.
+ bool bBoostOverride; // Set true if pilot override of the boost regulator was fitted.
+ // (Typically called 'war emergency power').
+ bool bTakeoffBoost; // Set true if extra takeoff / emergency boost above rated boost could be attained.
+ // (Typically by extra throttle movement past a mechanical 'gate').
+ double TakeoffBoost; // Sea-level takeoff boost in psi. (if fitted).
+ double RatedBoost[FG_MAX_BOOST_SPEEDS]; // Sea-level rated boost in psi.
+ double RatedAltitude[FG_MAX_BOOST_SPEEDS]; // Altitude at which full boost is reached (boost regulation ends)
+ // and at which power starts to fall with altitude [ft].
+ double RatedRPM[FG_MAX_BOOST_SPEEDS]; // Engine speed at which the rated power for each boost speed is delivered [rpm].
+ double RatedPower[FG_MAX_BOOST_SPEEDS]; // Power at rated throttle position at rated altitude [HP].
+ double BoostSwitchAltitude[FG_MAX_BOOST_SPEEDS - 1]; // Altitude at which switchover (currently assumed automatic)
+ // from one boost speed to next occurs [ft].
+ double BoostSwitchPressure[FG_MAX_BOOST_SPEEDS - 1]; // Pressure at which boost speed switchover occurs [Pa]
+ double BoostMul[FG_MAX_BOOST_SPEEDS]; // Pressure multipier of unregulated supercharger
+ double RatedMAP[FG_MAX_BOOST_SPEEDS]; // Rated manifold absolute pressure [Pa] (BCV clamp)
+ double TakeoffMAP[FG_MAX_BOOST_SPEEDS]; // Takeoff setting manifold absolute pressure [Pa] (BCV clamp)
+ double BoostSwitchHysteresis; // Pa.
+
+ double minMAP; // Pa
+ double maxMAP; // Pa
+ double MAP; // Pa
//
// Inputs (in addition to those in FGEngine).
//
- float p_amb; // Pascals
- float p_amb_sea_level; // Pascals
- float T_amb; // degrees Kelvin
- float RPM; // revolutions per minute
- float IAS; // knots
+ double p_amb; // Pascals
+ double p_amb_sea_level; // Pascals
+ double T_amb; // degrees Kelvin
+ double RPM; // revolutions per minute
+ double IAS; // knots
+ bool Magneto_Left;
+ bool Magneto_Right;
+ int Magnetos;
//
// Outputs (in addition to those in FGEngine).
//
- float rho_air;
- float volumetric_efficiency;
- float m_dot_air;
- float equivalence_ratio;
- float m_dot_fuel;
- float Percentage_Power;
- float HP;
- float combustion_efficiency;
-
- void Debug(void);
+ double rho_air;
+ double volumetric_efficiency;
+ double m_dot_air;
+ double equivalence_ratio;
+ double m_dot_fuel;
+ double Percentage_Power;
+ double HP;
+ double combustion_efficiency;
+ double ExhaustGasTemp_degK;
+ double EGT_degC;
+ double ManifoldPressure_inHg;
+ double CylinderHeadTemp_degK;
+ double OilPressure_psi;
+ double OilTemp_degK;
+
+ void Debug(int from);
};
-
+}
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#endif
projects / flightgear.git / blobdiff