Updated to latest JSBSim, including preliminary support for

[flightgear.git] / src / FDM / JSBSim / FGPiston.cpp

diff --git a/src/FDM/JSBSim/FGPiston.cpp b/src/FDM/JSBSim/FGPiston.cpp
index 725499f1a68ecc21032fb64eabe5a9171e5e33a7..d7f8d1c2bae3d6f4e6fe5e79e1f91e6ded946e7c 100644 (file)
--- a/src/FDM/JSBSim/FGPiston.cpp
+++ b/src/FDM/JSBSim/FGPiston.cpp
@@ -1,7 +1,8 @@
 /*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 
  Module:       FGPiston.cpp
- Author:       Jon S. Berndt
+ Author:       Jon S. Berndt, JSBSim framework
+               Dave Luff, Piston engine model
  Date started: 09/12/2000
  Purpose:      This module models a Piston engine
 
@@ -85,6 +86,7 @@ FGPiston::FGPiston(FGFDMExec* exec, FGConfigFile* Eng_cfg) : FGEngine(exec),
   crank_counter = 0;
   EngineNumber = 0;
   OilTemp_degK = 298;
+  ManifoldPressure_inHg = Atmosphere->GetPressure() * 0.014138; // psf to in Hg
 
   dt = State->Getdt();
 
@@ -285,8 +287,12 @@ void FGPiston::doEngineStartup(void)
 
 void FGPiston::doManifoldPressure(void)
 {
-  ManifoldPressure_inHg = MinManifoldPressure_inHg +
-    (Throttle * (MaxManifoldPressure_inHg - MinManifoldPressure_inHg));
+  if (Running || Cranking) {
+    ManifoldPressure_inHg = MinManifoldPressure_inHg +
+            (Throttle * (MaxManifoldPressure_inHg - MinManifoldPressure_inHg));
+  } else {
+    ManifoldPressure_inHg = Atmosphere->GetPressure() * 0.014138; // psf to in Hg
+  }  
 }
 
 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
@@ -390,13 +396,24 @@ void FGPiston::doEnginePower(void)
 
 void FGPiston::doEGT(void)
 {
-  combustion_efficiency = Lookup_Combustion_Efficiency->GetValue(equivalence_ratio);
-  double enthalpy_exhaust = m_dot_fuel * calorific_value_fuel * 
-    combustion_efficiency * 0.33;
-  double heat_capacity_exhaust = (Cp_air * m_dot_air) + (Cp_fuel * m_dot_fuel);
-  double delta_T_exhaust = enthalpy_exhaust / heat_capacity_exhaust;
-  ExhaustGasTemp_degK = T_amb + delta_T_exhaust;
-  ExhaustGasTemp_degK *= 0.444 + ((0.544 - 0.444) * Percentage_Power / 100.0);
+  double delta_T_exhaust;
+  double enthalpy_exhaust;
+  double heat_capacity_exhaust;
+  double dEGTdt;
+
+  if ((Running) && (m_dot_air > 0.0)) {  // do the energy balance
+    combustion_efficiency = Lookup_Combustion_Efficiency->GetValue(equivalence_ratio);
+    enthalpy_exhaust = m_dot_fuel * calorific_value_fuel * 
+                              combustion_efficiency * 0.33;
+    heat_capacity_exhaust = (Cp_air * m_dot_air) + (Cp_fuel * m_dot_fuel);
+    delta_T_exhaust = enthalpy_exhaust / heat_capacity_exhaust;
+    ExhaustGasTemp_degK = T_amb + delta_T_exhaust;
+    ExhaustGasTemp_degK *= 0.444 + ((0.544 - 0.444) * Percentage_Power / 100.0);
+  } else {  // Drop towards ambient - guess an appropriate time constant for now
+    dEGTdt = (298.0 - ExhaustGasTemp_degK) / 100.0;
+    delta_T_exhaust = dEGTdt * dt;
+    ExhaustGasTemp_degK += delta_T_exhaust;
+  }
 }
 
 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
@@ -553,5 +570,11 @@ void FGPiston::Debug(int from)
   }
   if (debug_lvl & 16) { // Sanity checking
   }
+  if (debug_lvl & 64) {
+    if (from == 0) { // Constructor
+      cout << IdSrc << endl;
+      cout << IdHdr << endl;
+    }
+  }
 }