Limited Measures

摘要

A wing's true angle of attack (AOA) is unknown; it can only be estimated by a measuring device mounted on the airplane somewhere. Furthermore, these devices have inherent errors that must be addressed. Many aircraft have stall sensors mounted on the fuselage to reduce the effects of changes in wing configuration. Nearer to the aircraft's nose, the airflow is cleaner and the boundary layer is thin, minimizing the required probe height. But the angle of airflow around the nose is not the same as at the wing. Nose landing-gear doors will influence the airflow near the sensor. While pitching the nose up, the local flow angle is reduced, causing the reading to be too low. Errors can be significant at sideslip angles that may occur during short final approaches or with an engine out.