SGPropertyNode_ptr _serviceable_node;
SGPropertyNode_ptr _total_pressure_node;
SGPropertyNode_ptr _static_pressure_node;
SGPropertyNode_ptr _density_node;
SGPropertyNode_ptr _speed_node;
SGPropertyNode_ptr _serviceable_node;
SGPropertyNode_ptr _total_pressure_node;
SGPropertyNode_ptr _static_pressure_node;
SGPropertyNode_ptr _density_node;
SGPropertyNode_ptr _speed_node;