Vivian Meazza:

I had to reverse a number of signs to get it right. I took the opportunity
to add roll to the submodel so that droptanks will come off with the right
orientation. I have neither added the rotational speed to the submodel, nor
yaw, so if you release droptanks with  significant roll rate or yaw angle on
the aircraft the submodel will not be quite right. Straight and level, or
nearly so, is fine.

src/AIModel/AIBallistic.cxx

@@ -35,6 +35,7 @@ FGAIBallistic::FGAIBallistic(FGAIManager* mgr) {
     life_timer = 0.0;
 	gravity = 32;
 //	buoyancy = 64;
+    no_roll = false;
 	}
 
 FGAIBallistic::~FGAIBallistic() {
@@ -46,6 +47,7 @@ bool FGAIBallistic::init() {
    aero_stabilized = true;
    hdg = azimuth;
    pitch = elevation;
+   roll = rotation;
    Transform();
    return true;
 }
@@ -78,6 +80,9 @@ void FGAIBallistic::setElevation(double el) {
    pitch = elevation = el;
 }
 
+void FGAIBallistic::setRoll(double rl) {
+   rotation = rl;
+}
 
 void FGAIBallistic::setStabilization(bool val) {
    aero_stabilized = val;
@@ -171,3 +176,4 @@ double FGAIBallistic::_getTime() const {
    return life_timer;
 }
 
+// end AIBallistic

src/AIModel/AIBallistic.hxx

@@ -38,6 +38,7 @@ public:
 
     void setAzimuth( double az );
     void setElevation( double el );
+	void setRoll( double rl );
     void setStabilization( bool val );
     void setDragArea( double a );
     void setLife( double seconds );
@@ -52,6 +53,7 @@ private:
 
     double azimuth;         // degrees true
     double elevation;       // degrees
+	double rotation;        // degrees
     double hs;              // horizontal speed (fps)
     bool aero_stabilized;   // if true, object will point where it's going
     double drag_area;       // equivalent drag area in ft2

src/AIModel/AIManager.cxx

@@ -202,6 +202,7 @@ FGAIManager::createBallistic( FGAIModelEntity *entity ) {
 	    ai_ballistic->setWind_from_east(entity->wind_from_east);
 	    ai_ballistic->setWind_from_north(entity->wind_from_north);
 	    ai_ballistic->setWind(entity->wind);
+		ai_ballistic->setRoll(entity->roll);
         ai_ballistic->init();
         ai_ballistic->bind();
         return ai_ballistic;

src/Systems/submodel.cxx

@@ -1,4 +1,3 @@
-
 // submodel.cxx - models a releasable submodel.
 // Written by Dave Culp, started Aug 2004
 //
@@ -117,6 +116,7 @@ SubmodelSystem::release (submodel* sm, double dt)
   entity.altitude = IC.alt;
   entity.azimuth = IC.azimuth;
   entity.elevation = IC.elevation;
+  entity.roll = IC.roll;
   entity.speed = IC.speed;
   entity.eda = sm->drag_area;
   entity.life = sm->life;
@@ -200,8 +200,8 @@ SubmodelSystem::transform( submodel* sm)
   IC.lat =        _user_lat_node->getDoubleValue();    
   IC.lon =        _user_lon_node->getDoubleValue();	   
   IC.alt =        _user_alt_node->getDoubleValue();    
-  IC.roll =     - _user_roll_node->getDoubleValue();    // rotation about x axis (-ve)
-  IC.elevation = - _user_pitch_node->getDoubleValue();   // rotation about y axis (-ve)
+  IC.roll =       _user_roll_node->getDoubleValue();    // rotation about x axis 
+  IC.elevation =  _user_pitch_node->getDoubleValue();   // rotation about y axis 
   IC.azimuth =    _user_heading_node->getDoubleValue(); // rotation about z axis
   
   IC.speed =           _user_speed_node->getDoubleValue();
@@ -219,10 +219,10 @@ SubmodelSystem::transform( submodel* sm)
 
 // pre-process the trig functions
 
-    cosRx = cos(IC.roll * SG_DEGREES_TO_RADIANS);
-    sinRx = sin(IC.roll * SG_DEGREES_TO_RADIANS);
-    cosRy = cos(IC.elevation * SG_DEGREES_TO_RADIANS);
-    sinRy = sin(IC.elevation * SG_DEGREES_TO_RADIANS);
+    cosRx = cos(-IC.roll * SG_DEGREES_TO_RADIANS);
+    sinRx = sin(-IC.roll * SG_DEGREES_TO_RADIANS);
+    cosRy = cos(-IC.elevation * SG_DEGREES_TO_RADIANS);
+    sinRy = sin(-IC.elevation * SG_DEGREES_TO_RADIANS);
     cosRz = cos(IC.azimuth * SG_DEGREES_TO_RADIANS);
     sinRz = sin(IC.azimuth * SG_DEGREES_TO_RADIANS);
 
@@ -265,7 +265,7 @@ SubmodelSystem::transform( submodel* sm)
    
    // Get submodel initial velocity vector angles in XZ and XY planes.
    // This needs to be fixed. This vector should be added to aircraft's vector. 
-   IC.elevation += (sm->yaw_offset * sinRx) - (sm->pitch_offset * cosRx);
+   IC.elevation += (sm->yaw_offset * sinRx) + (sm->pitch_offset * cosRx);
    IC.azimuth   += (sm->yaw_offset * cosRx) - (sm->pitch_offset * sinRx);
  
    // For now assume vector is close to airplane's vector.  This needs to be fixed.
@@ -305,9 +305,8 @@ SubmodelSystem::transform( submodel* sm)
 	 }
   }
 	 
-   
-   
-   IC.elevation = atan(IC.total_speed_down/sqrt(IC.total_speed_north * IC.total_speed_north + 
+    IC.elevation = -atan(IC.total_speed_down/sqrt(IC.total_speed_north * 
+                       IC.total_speed_north + 
                        IC.total_speed_east * IC.total_speed_east)) * SG_RADIANS_TO_DEGREES;
 
 }
@@ -323,3 +322,4 @@ SubmodelSystem::updatelat(double lat)
 // end of submodel.cxx
 
 
+

src/Systems/submodel.hxx

@@ -127,3 +127,4 @@ private:
 };
 
 #endif // __SYSTEMS_SUBMODEL_HXX
+