4 ms·

The rules that govern the structural integrity of airliners should not include asterisks.

• marvin 17y ago
  This is actually a huge point of misunderstanding among pilots. The angle of attack (alpha) is the angle between the wing and the airflow. If you increase alpha above a certain angle, the wing stalls, and ceases generating lift. Stalls are commonly encountered when flying really slow, but can occur at any speed. Pull the stick hard enough, and the elevator rudder will increase alpha above the threshold, momentarily causing the wings to cease generating lift and no longer stress the airframe. The lifting force generated by the wings is proportional to the angle of attack. However, when the airplane reaches a certain airspeed, flying the wings at an alpha just below stalling will cause the wings to generate more lift (measured in accelleration, or G units) than the airframe is designed to handle. This is the "maneuvering speed", the maximum speed at which full rudder deflection in smooth air will not cause the plane to exceed its design loads. The misunderstanding lies in that this speed is considered an absolute safe speed to do whatever you want with the controls. This is not the case. Turbulence, the airframe's current position in relation to the airflow, the plane's attitude and current position of the flight control surfaces can all add to the forces that work on the airframe. So when you pull 4G at the maximum maneuvering speed and encounter a 2G gust of turbulence, the air works 6Gs on the airframe, which will cause you to exceed the design specifications. Every professional pilot should know this, but it wouldn't surprise me if there are some who don't. It is really, really common among hobbyist pilots.