else if (token == "IDLERPM") *Eng_cfg >> IdleRPM;
else if (token == "MAXTHROTTLE") *Eng_cfg >> MaxThrottle;
else if (token == "MINTHROTTLE") *Eng_cfg >> MinThrottle;
- else if (token == "SLFUELFLOWMAX") *Eng_cfg >> SLFuelFlowMax;
else cerr << "Unhandled token in Engine config file: " << token << endl;
}
double FGPiston::Calculate(double PowerRequired)
{
- // FIXME: calculate from actual fuel flow
ConsumeFuel();
Throttle = FCS->GetThrottlePos(EngineNumber);
IAS = Auxiliary->GetVcalibratedKTS();
- if (Mixture >= 0.5) {
doEngineStartup();
doManifoldPressure();
doAirFlow();
doFuelFlow();
- doEnginePower();
+
+ //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();
doEGT();
doCHT();
doOilTemperature();
doOilPressure();
- } else {
- HP = 0;
- }
PowerAvailable = (HP * hptoftlbssec) - PowerRequired;
return PowerAvailable;
void FGPiston::doEngineStartup(void)
{
- // TODO: check magnetos, spark, starter, etc. and decide whether
- // engine is running
-
// Check parameters that may alter the operating state of the engine.
// (spark, fuel, starter motor etc)
bool spark;
if (Magnetos > 1) Magneto_Right = true;
// Assume we have fuel for now
- fuel = true;
+ fuel = !Starved;
// Check if we are turning the starter motor
if (Cranking != Starter) {
}
//Check mode of engine operation
- // ACK - unfortunately this hack doesn't work in JSBSim since the RPM is reset
- // each iteration by the propeller :-(
if (Cranking) {
crank_counter++;
if (RPM <= 480) {
- RPM += 100;
- if (RPM > 480)
- RPM = 480;
+ // Do nothing !! - cranking power output is now handled in the doPower section
} else {
// consider making a horrible noise if the starter is engaged with
// the engine running
}
- // TODO - find a better guess at cranking speed
}
// if ((!Running) && (spark) && (fuel) && (crank_counter > 120)) {
if ((!Running) && (spark) && (fuel)) {
// start the engine if revs high enough
- if (RPM > 450) {
- // For now just instantaneously start but later we should maybe crank for
- // a bit
- Running = true;
- // RPM = 600;
+ if (Cranking) {
+ if ((RPM > 450) && (crank_counter > 175)) {
+ //Add a little delay to startup on the starter
+ Running = true;
+ }
+ } else {
+ if (RPM > 450) {
+ Running = true;
+ //This allows us to in-air start when windmilling
+ }
}
}
/**
* Calculate the air flow through the engine.
*
+ * At this point, ManifoldPressure_inHg still represents the sea-level
+ * MP, not adjusted for altitude.
+ *
* Inputs: p_amb, R_air, T_amb, ManifoldPressure_inHg, Displacement,
* RPM, volumetric_efficiency
*
double thi_sea_level = 1.3 * Mixture;
equivalence_ratio = thi_sea_level * p_amb_sea_level / p_amb;
m_dot_fuel = m_dot_air / 14.7 * equivalence_ratio;
+ FuelFlow_gph = m_dot_fuel
+ * 3600 // seconds to hours
+ * 2.2046 // kg to lb
+ / 6.6; // lb to gal_us of kerosene
}
//%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
void FGPiston::doEnginePower(void)
{
- double True_ManifoldPressure_inHg = ManifoldPressure_inHg * p_amb / p_amb_sea_level;
- double ManXRPM = True_ManifoldPressure_inHg * RPM;
+ ManifoldPressure_inHg *= p_amb / p_amb_sea_level;
+ if (Running) {
+ double ManXRPM = ManifoldPressure_inHg * RPM;
// FIXME: this needs to be generalized
- Percentage_Power = (6e-9 * ManXRPM * ManXRPM) + (8e-4 * ManXRPM) - 1.0;
- double T_amb_degF = (T_amb * 1.8) - 459.67;
- double T_amb_sea_lev_degF = (288 * 1.8) - 459.67;
- Percentage_Power =
- Percentage_Power + ((T_amb_sea_lev_degF - T_amb_degF) * 7 /120);
- double Percentage_of_best_power_mixture_power =
- Power_Mixture_Correlation->GetValue(14.7 / equivalence_ratio);
- Percentage_Power =
- Percentage_Power * Percentage_of_best_power_mixture_power / 100.0;
- if (Percentage_Power < 0.0)
- Percentage_Power = 0.0;
- else if (Percentage_Power > 100.0)
- Percentage_Power = 100.0;
- HP = Percentage_Power * MaxHP / 100.0;
-
- //Hack
- if (!Running) {
+ Percentage_Power = (6e-9 * ManXRPM * ManXRPM) + (8e-4 * ManXRPM) - 1.0;
+ double T_amb_degF = (T_amb * 1.8) - 459.67;
+ double T_amb_sea_lev_degF = (288 * 1.8) - 459.67;
+ Percentage_Power =
+ Percentage_Power + ((T_amb_sea_lev_degF - T_amb_degF) * 7 /120);
+ double Percentage_of_best_power_mixture_power =
+ Power_Mixture_Correlation->GetValue(14.7 / equivalence_ratio);
+ Percentage_Power =
+ Percentage_Power * Percentage_of_best_power_mixture_power / 100.0;
+ if (Percentage_Power < 0.0)
+ Percentage_Power = 0.0;
+ else if (Percentage_Power > 100.0)
+ Percentage_Power = 100.0;
+ HP = Percentage_Power * MaxHP / 100.0;
+ } else {
+ // Power output when the engine is not running
if (Cranking) {
- if (RPM < 480) {
- HP = 3.0 + ((480 - RPM) / 10.0);
+ if (RPM < 10) {
+ HP = 3.0; // This is a hack to prevent overshooting the idle rpm in the first time step
+ // It may possibly need to be changed if the prop model is changed.
+ } else if (RPM < 480) {
+ HP = 3.0 + ((480 - RPM) / 10.0);
+ // This is a guess - would be nice to find a proper starter moter torque curve
} else {
HP = 3.0;
}
cout << " IdleRPM: " << IdleRPM << endl;
cout << " MaxThrottle: " << MaxThrottle << endl;
cout << " MinThrottle: " << MinThrottle << endl;
- cout << " SLFuelFlowMax: " << SLFuelFlowMax << endl;
cout << endl;
cout << " Combustion Efficiency table:" << endl;
}
}
+double
+FGPiston::CalcFuelNeed(void)
+{
+ return FuelFlow_gph / 3600 * State->Getdt() * Propulsion->GetRate();
+}
projects / flightgear.git / blobdiff