+ return PointMassCG;
+}
+
+//%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+FGMatrix33& FGMassBalance::CalculatePMInertias(void)
+{
+ unsigned int size;
+
+ size = PointMassLoc.size();
+ if (size == 0) return pmJ;
+
+ pmJ = FGMatrix33();
+
+ for (unsigned int i=0; i<size; i++)
+ pmJ += GetPointmassInertia( lbtoslug * PointMassWeight[i], PointMassLoc[i] );
+
+ return pmJ;
+}
+
+//%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+FGColumnVector3 FGMassBalance::StructuralToBody(const FGColumnVector3& r) const
+{
+ // Under the assumption that in the structural frame the:
+ //
+ // - X-axis is directed afterwards,
+ // - Y-axis is directed towards the right,
+ // - Z-axis is directed upwards,
+ //
+ // (as documented in http://jsbsim.sourceforge.net/JSBSimCoordinates.pdf)
+ // we have to subtract first the center of gravity of the plane which
+ // is also defined in the structural frame:
+ //
+ // FGColumnVector3 cgOff = r - vXYZcg;
+ //
+ // Next, we do a change of units:
+ //
+ // cgOff *= inchtoft;
+ //
+ // And then a 180 degree rotation is done about the Y axis so that the:
+ //
+ // - X-axis is directed forward,
+ // - Y-axis is directed towards the right,
+ // - Z-axis is directed downward.
+ //
+ // This is needed because the structural and body frames are 180 degrees apart.
+
+ return FGColumnVector3(inchtoft*(vXYZcg(1)-r(1)),
+ inchtoft*(r(2)-vXYZcg(2)),
+ inchtoft*(vXYZcg(3)-r(3)));
+}
+
+//%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+void FGMassBalance::bind(void)
+{
+ typedef double (FGMassBalance::*PMF)(int) const;
+ PropertyManager->Tie("inertia/mass-slugs", this,
+ &FGMassBalance::GetMass);
+ PropertyManager->Tie("inertia/weight-lbs", this,
+ &FGMassBalance::GetWeight);
+ PropertyManager->Tie("inertia/cg-x-ft", this,1,
+ (PMF)&FGMassBalance::GetXYZcg);
+ PropertyManager->Tie("inertia/cg-y-ft", this,2,
+ (PMF)&FGMassBalance::GetXYZcg);
+ PropertyManager->Tie("inertia/cg-z-ft", this,3,
+ (PMF)&FGMassBalance::GetXYZcg);
+}
+
+//%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+void FGMassBalance::unbind(void)
+{
+ PropertyManager->Untie("inertia/mass-slugs");
+ PropertyManager->Untie("inertia/weight-lbs");
+ PropertyManager->Untie("inertia/cg-x-ft");
+ PropertyManager->Untie("inertia/cg-y-ft");
+ PropertyManager->Untie("inertia/cg-z-ft");