Airplane Stalls

Posted by Admin on

Simply stated, an aircraft cannot stall unless it exceeds its critical angle of attack. Remember that angle of attack is the angle between the chord line of the wing and the relative wind. Most airfoils become critical and stall somewhere between 15 and 20 degrees of pitch. Don’t exceed your critical angle of attack and you won’t find yourself in a stall. It’s that simple, and yet people continue to stall, spin, and crash.

A plane can stall at any airspeed. A normal stall is usually entered by slowing the airplane to the point that it stalls at a slow airspeed. But if you have flown on a hot summer day, when the turbulence is banging against the plane, and heard the stall warning horn go off as a result of turbulence, you have encountered a situation that could result in a stall. If you have put the airplane into a turn and pulled back hard on the yoke and felt the plane shudder, this is also an indicator of a high-speed, or accelerated, stall. Figure illustrates a plane flying along at cruise speeds in level flight, the horizontal arrow indicating the direction of flight. The second arrow represents a gust of wind from turbulence. This wind gust can result in an angle of attack that briefly exceeds the critical angle of attack, causing part or all of the wing to stall.

A normal stall is one that does not require abrupt control inputs to initiate. For example, a normal stall would be entered in the manner discussed for slow flight entry, but without subsequent addition of power to stabilize the speed. The airplane continues to decelerate in level flight until the increasing angle of attack causes turbulent airflow—a stall.

In contrast, an accelerated stall normally takes place at a higher airspeed, with rapid or excessive control inputs initiating the stall. The airplane is normally under higher g-loads and stalls more abruptly.

Accelerated stalls are usually the result of a need to maneuver quickly. As we discuss normal and accelerated stalls, keep this difference in mind.

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