YASim now supports the new fuel.nas fuel management system. It

reads the /consumables tree for input to determine weights, but
places output only in /engines/engine[n]/fuel-consumed-lbs where
it gets picked up by the Nasal code.

src/FDM/YASim/Airplane.cpp

@@ -78,32 +78,9 @@ void Airplane::iterate(float dt)
     _model.iterate();
 }
 
-void Airplane::consumeFuel(float dt)
+void Airplane::calcFuelWeights()
 {
-    // This is a really simple implementation that assumes all engines
-    // draw equally from all tanks in proportion to the amount of fuel
-    // stored there.  Needs to be fixed, but that has to wait for a
-    // decision as to what the property interface will look like.
-    int i, outOfFuel = 0;
-    float fuelFlow = 0, totalFuel = 0.00001; // <-- overflow protection
-    for(i=0; i<_thrusters.size(); i++)
-        fuelFlow += ((ThrustRec*)_thrusters.get(i))->thruster->getFuelFlow();
-    for(i=0; i<_tanks.size(); i++)
-        totalFuel += ((Tank*)_tanks.get(i))->fill;
-    for(i=0; i<_tanks.size(); i++) {
-        Tank* t = (Tank*)_tanks.get(i);
-        t->fill -= dt * fuelFlow * (t->fill/totalFuel);
-        if(t->fill <= 0) {
-            t->fill = 0;
-            outOfFuel = 1;
-        }
-    }
-    if(outOfFuel)
-        for(int i=0; i<_thrusters.size(); i++)
-            ((ThrustRec*)_thrusters.get(i))->thruster->setFuelState(false);
-
-    // Set the tank masses on the RigidBody
-    for(i=0; i<_tanks.size(); i++) {
+    for(int i=0; i<_tanks.size(); i++) {
         Tank* t = (Tank*)_tanks.get(i);
         _model.getBody()->setMass(t->handle, t->fill);
     }
@@ -233,6 +210,11 @@ float Airplane::getFuel(int tank)
     return ((Tank*)_tanks.get(tank))->fill;
 }
 
+float Airplane::setFuel(int tank, float fuel)
+{
+    ((Tank*)_tanks.get(tank))->fill = fuel;
+}
+
 float Airplane::getFuelDensity(int tank)
 {
     return ((Tank*)_tanks.get(tank))->density;

src/FDM/YASim/Airplane.hpp

@@ -18,7 +18,7 @@ public:
     ~Airplane();
 
     void iterate(float dt);
-    void consumeFuel(float dt);
+    void calcFuelWeights();
 
     ControlMap* getControlMap();
     Model* getModel();
@@ -60,9 +60,14 @@ public:
     int numGear();
     Gear* getGear(int g);
 
+    int numThrusters() { return _thrusters.size(); }
+    Thruster* getThruster(int n) {
+        return ((ThrustRec*)_thrusters.get(n))->thruster; }
+    
     int numTanks();
     void setFuelFraction(float frac); // 0-1, total amount of fuel
     float getFuel(int tank); // in kg!
+    float setFuel(int tank, float fuel); // in kg!
     float getFuelDensity(int tank); // kg/m^3
     float getTankCapacity(int tank);
 

src/FDM/YASim/FGFDM.cpp

@@ -82,9 +82,24 @@ void FGFDM::iterate(float dt)
     getExternalInput(dt);
     _airplane.iterate(dt);
 
-    if(fgGetBool("/sim/freeze/fuel") != true)
-        _airplane.consumeFuel(dt);
+    // Do fuel stuff (FIXME: should stash SGPropertyNode objects here)
+    char buf[256];
+    for(int i=0; i<_airplane.numThrusters(); i++) {
+        Thruster* t = _airplane.getThruster(i);
 
+        sprintf(buf, "/engines/engine[%d]/out-of-fuel", i);
+        t->setFuelState(!fgGetBool(buf));
+
+        sprintf(buf, "/engines/engine[%d]/fuel-consumed-lbs", i);
+        double consumed = fgGetDouble(buf) + dt * t->getFuelFlow();
+        fgSetDouble(buf, consumed);
+    }
+    for(int i=0; i<_airplane.numTanks(); i++) {
+        sprintf(buf, "/consumables/fuel/tank[%d]/level-lbs", i);
+        _airplane.setFuel(i, LBS2KG * fgGetFloat(buf));
+    } 
+    _airplane.calcFuelWeights();
+    
     setOutputProperties();
 }
 
@@ -98,6 +113,23 @@ void FGFDM::init()
     // Allows the user to start with something other than full fuel
     _airplane.setFuelFraction(fgGetFloat("/sim/fuel-fraction", 1));
 
+    // Read out the resulting fuel state
+    char buf[256];
+    for(int i=0; i<_airplane.numTanks(); i++) {
+        sprintf(buf, "/consumables/fuel/tank[%d]/level-lbs", i);
+        fgSetDouble(buf, _airplane.getFuel(i) * KG2LBS);
+
+        double density = _airplane.getFuelDensity(i);
+        sprintf(buf, "/consumables/fuel/tank[%d]/density-ppg", i);
+        fgSetDouble(buf, density * (KG2LBS/CM2GALS));
+
+        sprintf(buf, "/consumables/fuel/tank[%d]/level-gal_us", i);
+        fgSetDouble(buf, _airplane.getFuel(i) * CM2GALS / density);
+
+        sprintf(buf, "/consumables/fuel/tank[%d]/capacity-gal_us", i);
+        fgSetDouble(buf, CM2GALS * _airplane.getTankCapacity(i)/density);
+    }    
+
     // This has a nasty habit of being false at startup.  That's not
     // good.
     fgSetBool("/controls/gear/gear-down", true);
@@ -372,24 +404,6 @@ void FGFDM::setOutputProperties()
         p->prop->setFloatValue(val);
     }
 
-    float totalFuel = 0, totalCap = 0;
-    float fuelDensity = 720; // in kg/m^3, default to gasoline: ~6 lb/gal
-    for(i=0; i<_airplane.numTanks(); i++) {
-        fuelDensity = _airplane.getFuelDensity(i);
-	sprintf(buf, "/consumables/fuel/tank[%d]/level-gal_us", i);
-	fgSetFloat(buf, CM2GALS*_airplane.getFuel(i)/fuelDensity);
-	sprintf(buf, "/consumables/fuel/tank[%d]/level-lbs", i);
-	fgSetFloat(buf, KG2LBS*_airplane.getFuel(i));
-        totalFuel += _airplane.getFuel(i);
-        totalCap += _airplane.getTankCapacity(i);
-    }
-    if(totalCap != 0) {
-        fgSetFloat("/consumables/fuel/total-fuel-lbs", KG2LBS*totalFuel);
-        fgSetFloat("/consumables/fuel/total-fuel-gals",
-                   CM2GALS*totalFuel/fuelDensity);
-        fgSetFloat("/consumables/fuel/total-fuel-norm", totalFuel/totalCap);
-    }
-
     for(i=0; i<_airplane.getNumRotors(); i++) {
         Rotor*r=(Rotor*)_airplane.getRotor(i);
         int j = 0;
@@ -418,6 +432,7 @@ void FGFDM::setOutputProperties()
         }
     }
 
+    float fuelDensity = _airplane.getFuelDensity(0); // HACK
     for(i=0; i<_thrusters.size(); i++) {
 	EngRec* er = (EngRec*)_thrusters.get(i);
         Thruster* t = er->eng;

src/FDM/YASim/yasim-test.cpp

@@ -14,6 +14,8 @@ bool fgSetBool(char const * name, bool val) { return false; }
 bool fgGetBool(char const * name, bool def) { return false; }
 SGPropertyNode* fgGetNode (const char * path, bool create) { return 0; }
 float fgGetFloat (const char * name, float defaultValue) { return 0; }
+float fgGetDouble (const char * name, double defaultValue) { return 0; }
+float fgSetDouble (const char * name, double defaultValue) { return 0; }
 
 static const float RAD2DEG = 57.2957795131;