+void PerformanceData::initFromProps(SGPropertyNode *db_node)
+{
+// read the values, using the existing values as defaults
+ _acceleration = db_node->getDoubleValue("acceleration-kts-hour", _acceleration);
+ _deceleration = db_node->getDoubleValue("deceleration-kts-hour", _deceleration);
+ _climbRate = db_node->getDoubleValue("climbrate-fpm", _climbRate);
+ _descentRate = db_node->getDoubleValue("decentrate-fpm", _descentRate);
+ _vRotate = db_node->getDoubleValue("rotate-speed-kts", _vRotate);
+ _vTakeOff = db_node->getDoubleValue("takeoff-speed-kts", _vTakeOff);
+ _vClimb = db_node->getDoubleValue("climb-speed-kts", _vClimb);
+ _vCruise = db_node->getDoubleValue("cruise-speed-kts", _vCruise);
+ _vDescent = db_node->getDoubleValue("decent-speed-kts", _vDescent);
+ _vApproach = db_node->getDoubleValue("approach-speed-kts", _vApproach);
+ _vTouchdown = db_node->getDoubleValue("touchdown-speed-kts", _vTouchdown);
+ _vTaxi = db_node->getDoubleValue("taxi-speed-kts", _vTaxi);
+}
+
+double PerformanceData::actualSpeed(FGAIAircraft* ac, double tgt_speed, double dt, bool maxBrakes) {