void FGRocket::Calculate(void)
{
if (FDMExec->IntegrationSuspended()) return;
RunPreFunctions();
PropellantFlowRate = (FuelExpended + OxidizerExpended)/in.TotalDeltaT;
TotalPropellantExpended += FuelExpended + OxidizerExpended;
// If Isp has been specified as a function, override the value of Isp to that, otherwise
// assume a constant value is given.
if (isp_function) Isp = isp_function->GetValue();
// If there is a thrust table, it is a function of propellant burned. The
// engine is started when the throttle is advanced to 1.0. After that, it
// burns without regard to throttle setting.
if (ThrustTable != 0L) { // Thrust table given -> Solid fuel used
if ((in.ThrottlePos[EngineNumber] == 1 || BurnTime > 0.0 ) && !Starved) {
VacThrust = ThrustTable->GetValue(TotalPropellantExpended)
* (ThrustVariation + 1)
* (TotalIspVariation + 1);
if (BurnTime <= BuildupTime && BuildupTime > 0.0) {
VacThrust *= sin((BurnTime/BuildupTime)*M_PI/2.0);
// VacThrust *= (1-cos((BurnTime/BuildupTime)*M_PI))/2.0; // 1 - cos approach
}
BurnTime += in.TotalDeltaT; // Increment burn time
} else {
VacThrust = 0.0;
}
} else { // liquid fueled rocket assumed
if (in.ThrottlePos[EngineNumber] < MinThrottle || Starved) { // Combustion not supported
PctPower = 0.0; // desired thrust
Flameout = true;
VacThrust = 0.0;
} else { // Calculate thrust
// PctPower = Throttle / MaxThrottle; // Min and MaxThrottle range from 0.0 to 1.0, normally.
PctPower = in.ThrottlePos[EngineNumber];
Flameout = false;
VacThrust = Isp * PropellantFlowRate;
}
} // End thrust calculations
LoadThrusterInputs();
It += Thruster->Calculate(VacThrust) * in.TotalDeltaT;
ItVac += VacThrust * in.TotalDeltaT;
RunPostFunctions();
}
void FGPiston::Calculate(void)
{
// Input values.
p_amb = in.Pressure * psftopa;
double p = in.TotalPressure * psftopa;
p_ram = (p - p_amb) * Ram_Air_Factor + p_amb;
T_amb = RankineToKelvin(in.Temperature);
RunPreFunctions();
TotalDeltaT = ( in.TotalDeltaT < 1e-9 ) ? 1.0 : in.TotalDeltaT;
/* The thruster controls the engine RPM because it encapsulates the gear ratio and other transmission variables */
RPM = Thruster->GetEngineRPM();
MeanPistonSpeed_fps = ( RPM * Stroke) / (360); // AKA 2 * (RPM/60) * ( Stroke / 12) or 2NS
IAS = in.Vc;
doEngineStartup();
if (Boosted) doBoostControl();
doMAP();
doAirFlow();
doFuelFlow();
//Now that the fuel flow is done check if the mixture is too lean to run the engine
//Assume lean limit at 22 AFR for now - thats a thi of 0.668
//This might be a bit generous, but since there's currently no audiable warning of impending
//cutout in the form of misfiring and/or rough running its probably reasonable for now.
// if (equivalence_ratio < 0.668)
// Running = false;
doEnginePower();
if (IndicatedHorsePower < 0.1250) Running = false;
doEGT();
doCHT();
doOilTemperature();
doOilPressure();
if (Thruster->GetType() == FGThruster::ttPropeller) {
((FGPropeller*)Thruster)->SetAdvance(in.PropAdvance[EngineNumber]);
((FGPropeller*)Thruster)->SetFeather(in.PropFeather[EngineNumber]);
}
LoadThrusterInputs();
Thruster->Calculate(HP * hptoftlbssec);
RunPostFunctions();
}
void FGElectric::Calculate(void)
{
RunPreFunctions();
if (Thruster->GetType() == FGThruster::ttPropeller) {
((FGPropeller*)Thruster)->SetAdvance(in.PropAdvance[EngineNumber]);
((FGPropeller*)Thruster)->SetFeather(in.PropFeather[EngineNumber]);
}
RPM = Thruster->GetRPM() * Thruster->GetGearRatio();
HP = PowerWatts * in.ThrottlePos[EngineNumber] / hptowatts;
LoadThrusterInputs();
Thruster->Calculate(HP * hptoftlbssec);
RunPostFunctions();
}
void FGTurboProp::Calculate(void)
{
RunPreFunctions();
TAT = in.TAT_c;
ThrottlePos = in.ThrottlePos[EngineNumber];
/* The thruster controls the engine RPM because it encapsulates the gear ratio and other transmission variables */
RPM = Thruster->GetEngineRPM();
if (thrusterType == FGThruster::ttPropeller) {
((FGPropeller*)Thruster)->SetAdvance(in.PropAdvance[EngineNumber]);
((FGPropeller*)Thruster)->SetFeather(in.PropFeather[EngineNumber]);
((FGPropeller*)Thruster)->SetReverse(Reversed);
if (Reversed) {
((FGPropeller*)Thruster)->SetReverseCoef(ThrottlePos);
} else {
((FGPropeller*)Thruster)->SetReverseCoef(0.0);
}
if (Reversed) {
if (ThrottlePos < BetaRangeThrottleEnd) {
ThrottlePos = 0.0; // idle when in Beta-range
} else {
// when reversed:
ThrottlePos = (ThrottlePos-BetaRangeThrottleEnd)/(1-BetaRangeThrottleEnd) * ReverseMaxPower;
}
}
}
// When trimming is finished check if user wants engine OFF or RUNNING
if ((phase == tpTrim) && (in.TotalDeltaT > 0)) {
if (Running && !Starved) {
phase = tpRun;
N2 = IdleN2;
N1 = IdleN1;
OilTemp_degK = 366.0;
Cutoff = false;
} else {
phase = tpOff;
Cutoff = true;
Eng_ITT_degC = TAT;
Eng_Temperature = TAT;
OilTemp_degK = TAT+273.15;
}
}
if (!Running && Starter) {
if (phase == tpOff) {
phase = tpSpinUp;
if (StartTime < 0) StartTime=0;
}
}
if (!Running && !Cutoff && (N1 > 15.0)) {
phase = tpStart;
StartTime = -1;
}
if (Cutoff && (phase != tpSpinUp)) phase = tpOff;
if (in.TotalDeltaT == 0) phase = tpTrim;
if (Starved) phase = tpOff;
if (Condition >= 10) {
phase = tpOff;
StartTime=-1;
}
// limiter intervention wanted?
if (Ielu_max_torque > 0.0) {
double torque = 0.0;
if (thrusterType == FGThruster::ttPropeller) {
torque = ((FGPropeller*)(Thruster))->GetTorque();
} else if (thrusterType == FGThruster::ttRotor) {
torque = ((FGRotor*)(Thruster))->GetTorque();
}
if (Condition < 1) {
if ( abs(torque) > Ielu_max_torque && ThrottlePos >= OldThrottle ) {
ThrottlePos = OldThrottle - 0.1 * in.TotalDeltaT; //IELU down
Ielu_intervent = true;
} else if ( Ielu_intervent && ThrottlePos >= OldThrottle) {
ThrottlePos = OldThrottle + 0.05 * in.TotalDeltaT; //IELU up
Ielu_intervent = true;
} else {
Ielu_intervent = false;
}
} else {
Ielu_intervent = false;
}
OldThrottle = ThrottlePos;
}
switch (phase) {
case tpOff: HP = Off(); break;
case tpRun: HP = Run(); break;
case tpSpinUp: HP = SpinUp(); break;
case tpStart: HP = Start(); break;
default: HP = 0;
}
LoadThrusterInputs();
Thruster->Calculate(HP * hptoftlbssec);
RunPostFunctions();
}
