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[flightgear.git] / src / FDM / YASim / Jet.cpp

diff --git a/src/FDM/YASim/Jet.cpp b/src/FDM/YASim/Jet.cpp
index 599a25e63bbb31150ead363d31935bbff74a49ea..f80cac543daee572160a6247eee53b9733672b67 100644 (file)
--- a/src/FDM/YASim/Jet.cpp
+++ b/src/FDM/YASim/Jet.cpp
@@ -10,13 +10,14 @@ Jet::Jet()
     _reheat = 0;
     _rotControl = 0;
     _maxRot = 0;
+    _reverseThrust = false;
 
     // Initialize parameters for an early-ish subsonic turbojet.  More
     // recent turbofans will typically have a lower vMax, epr0, and
     // tsfc.
     _vMax = 800;
     _epr0 = 3.0;
-    _tsfc = 0.8;
+    _tsfc = 0.8f;
     _egt0 = 1050;
     _n1Min = 55;
     _n1Max = 102;
@@ -31,6 +32,7 @@ Jet::Jet()
     // And sanify the remaining junk, just in case.
     _running = true;
     _cranking = false;
+    _fuel = true;
     _epr = 1;
     _fuelFlow = 0;
     _egt = 273;
@@ -85,7 +87,7 @@ void Jet::setSpooling(float time)
     // 2.3 = -ln(0.1), i.e. x=2.3 is the 90% point we're defining
     // The extra fudge factor is there because the N1 speed (which
     // determines thrust) lags the N2 speed.
-    _decay = 1.5 * 2.3 / time;
+    _decay = 1.5f * 2.3f / time;
 }
 
 void Jet::setVectorAngle(float angle)
@@ -140,24 +142,30 @@ void Jet::integrate(float dt)
     const static float T0 = Atmosphere::getStdTemperature(0);
     const static float D0 = Atmosphere::getStdDensity(0);
 
-    float speed = -Math::dot3(_wind, _dir);
+    float spd = -Math::dot3(_wind, _dir);
 
     float statT, statP, statD;
-    Atmosphere::calcStaticAir(_pressure, _temp, _rho, speed,
+    Atmosphere::calcStaticAir(_pressure, _temp, _rho, spd,
                               &statP, &statT, &statD);
     _pressureCorrect = statP/P0;
     _tempCorrect = Math::sqrt(statT/T0);
 
+    // Handle running out of fuel.  This is a hack.  What should
+    // really happen is a simulation of ram air torque on the
+    // turbine.  This just forces the engine into ground idle.
+    if(_fuel == false)
+        _throttle = 0;
+
     // Linearly taper maxThrust to zero at vMax
-    float vCorr = 1 - (speed/_vMax);
+    float vCorr = spd<0 ? 1 : (spd<_vMax ? 1-spd/_vMax : 0);
 
     float maxThrust = _maxThrust * vCorr * (statD/D0);
-    _thrust = maxThrust * _throttle;
+    float setThrust = maxThrust * _throttle;
 
     // Now get a "beta" (i.e. EPR - 1) value.  The output values are
     // expressed as functions of beta.
     float ibeta0 = 1/(_epr0 - 1);
-    float betaTarget = (_epr0 - 1) * (_thrust/_maxThrust) * (P0/_pressure)
+    float betaTarget = (_epr0 - 1) * (setThrust/_maxThrust) * (P0/_pressure)
        * (_temp/statT);
     float n2Target = _n2Min + (betaTarget*ibeta0) * (_n2Max - _n2Min);
 
@@ -173,19 +181,22 @@ void Jet::integrate(float dt)
     // The actual thrust produced is keyed to the N1 speed.  Add the
     // afterburners in at the end.
     float betaN1 =  (_epr0-1) * (_n1 - _n1Min) / (_n1Max - _n1Min);
-    _thrust *= betaN1/(betaTarget+.00001); // blowup protection
+    _thrust = _maxThrust * betaN1/((_epr0-1)*(P0/_pressure)*(_temp/statT));
     _thrust *= 1 + _reheat*(_abFactor-1);
 
     // Finally, calculate the output variables.   Use a 80/20 mix of
     // the N2/N1 speeds as the key.
-    float beta = 0.8*betaN2 + 0.2*betaN1;
+    float beta = 0.8f*betaN2 + 0.2f*betaN1;
     _epr = beta + 1;
-    float ff0 = _maxThrust*_tsfc*(1/(3600*9.8)); // takeoff fuel flow, kg/s
+    float ff0 = _maxThrust*_tsfc*(1/(3600.0f*9.8f)); // takeoff fuel flow, kg/s
     _fuelFlow = ff0 * beta*ibeta0;
-    _fuelFlow *= 1 + (3.5 * _reheat * _abFactor); // Afterburners take
+    _fuelFlow *= 1 + (3.5f * _reheat * _abFactor); // Afterburners take
                                                  // 3.5 times as much
                                                  // fuel per thrust unit
     _egt = T0 + beta*ibeta0 * (_egt0 - T0);
+
+    // Thrust reverse handling:
+    if(_reverseThrust) _thrust *= -_reverseEff;
 }
 
 bool Jet::isRunning()