%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/
FGPiston::FGPiston(FGFDMExec* exec, FGConfigFile* Eng_cfg) : FGEngine(exec),
- CONVERT_CUBIC_INCHES_TO_METERS_CUBED(1.638706e-5),
R_air(287.3),
rho_fuel(800), // estimate
calorific_value_fuel(47.3e6),
crank_counter = 0;
EngineNumber = 0;
OilTemp_degK = 298;
- ManifoldPressure_inHg = Atmosphere->GetPressure() * 0.014138; // psf to in Hg
+ ManifoldPressure_inHg = Atmosphere->GetPressure() * psftoinhg; // psf to in Hg
dt = State->Getdt();
T_amb = Atmosphere->GetTemperature() * (5.0 / 9.0); // convert from Rankine to Kelvin
RPM = Propulsion->GetThruster(EngineNumber)->GetRPM();
- //if (RPM < IdleRPM) RPM = IdleRPM; // kludge
IAS = Auxiliary->GetVcalibratedKTS();
- if (Mixture >= 0.3) {
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;
crank_counter = 0;
}
- //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;
- } else {
- // consider making a horrible noise if the starter is engaged with
- // the engine running
- }
- // TODO - find a better guess at cranking speed
- }
+ if (Cranking) crank_counter++; //Check mode of engine operation
- // 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 (!Running && spark && fuel) { // start the engine if revs high enough
+ if (Cranking) {
+ if ((RPM > 450) && (crank_counter > 175)) // Add a little delay to startup
+ Running = true; // on the starter
+ } else {
+ if (RPM > 450) // This allows us to in-air start
+ Running = true; // when windmilling
}
}
- if ( (Running) && ((!spark)||(!fuel)) ) {
- // Cut the engine
- // note that we only cut the power - the engine may continue to
- // spin if the prop is in a moving airstream
- Running = false;
- }
+ // Cut the engine *power* - Note: the engine may continue to
+ // spin if the prop is in a moving airstream
+
+ if ( Running && (!spark || !fuel) ) Running = false;
- // And finally a last check for stalling
+ // Check for stalling (RPM = 0).
if (Running) {
- //Check if we have stalled the engine
if (RPM == 0) {
Running = false;
} else if ((RPM <= 480) && (Cranking)) {
- // Make sure the engine noise dosn't play if the engine won't
- // start due to eg mixture lever pulled out.
Running = false;
}
}
ManifoldPressure_inHg = MinManifoldPressure_inHg +
(Throttle * (MaxManifoldPressure_inHg - MinManifoldPressure_inHg));
} else {
- ManifoldPressure_inHg = Atmosphere->GetPressure() * 0.014138; // psf to in Hg
+ ManifoldPressure_inHg = Atmosphere->GetPressure() * psftoinhg; // psf to in Hg
}
}
{
rho_air = p_amb / (R_air * T_amb);
double rho_air_manifold = rho_air * ManifoldPressure_inHg / 29.6;
- double displacement_SI = Displacement * CONVERT_CUBIC_INCHES_TO_METERS_CUBED;
+ double displacement_SI = Displacement * in3tom3;
double swept_volume = (displacement_SI * (RPM/60)) / 2;
double v_dot_air = swept_volume * volumetric_efficiency;
m_dot_air = v_dot_air * rho_air_manifold;
void FGPiston::doEnginePower(void)
{
ManifoldPressure_inHg *= p_amb / p_amb_sea_level;
- double ManXRPM = ManifoldPressure_inHg * RPM;
+ 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;
}
double HeatCapacityCylinderHead = CpCylinderHead * MassCylinderHead;
- CylinderHeadTemp_degK = dqdt_cylinder_head / HeatCapacityCylinderHead;
+ CylinderHeadTemp_degK +=
+ (dqdt_cylinder_head / HeatCapacityCylinderHead) * dt;
}
//%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
{
double Oil_Press_Relief_Valve = 60; // FIXME: may vary by engine
double Oil_Press_RPM_Max = 1800; // FIXME: may vary by engine
- double Design_Oil_Temp = 85; // FIXME: may vary by engine
- // FIXME: WRONG!!! (85 degK???)
+ double Design_Oil_Temp = 358; // degK; FIXME: may vary by engine
double Oil_Viscosity_Index = 0.25;
OilPressure_psi = (Oil_Press_Relief_Valve / Oil_Press_RPM_Max) * RPM;
projects / flightgear.git / blobdiff