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  Why you don't use aileron in a stall.
                                 Russell Still, ATP, CFI/CFII, Master CFI
 


Watch this classic response as a wing drops during a power on stall. The student feels the left wing starting to drop and responds by turning the yoke to the right in a failing attempt to bring the wings back level. The airplane enters an incipient spin as the instructor coolly tells him to release the aileron input.

       

The wing drop starts at the 10 seconds mark and at 12 seconds the student cranks the ailerons to the right. Had the student simply released back pressure on the yoke instead of turning it, followed by a power reduction, the spin entry would have never occurred.

Wing drops occur frequently during stalls, usually the result of improper rudder use, propeller torque, and spiraling slipstream - the usual suspects for left turning tendencies. Proper use of rudder provides induced roll motion and can easily counter these effects.

As the left wing dropped, a yaw to the left was induced.  Since the airplane was stalled, this yaw started the entry into the incipient spin phase. The pilot's reaction of applying opposite aileron did the opposite of what he intended. Turbulent air over the top of the wing reduced the effectiveness of the up aileron on the right side. But the down aileron on the left was extended into unstalled air and created additional drag further exacerbating the yawing motion. Additionally, the increased angle of attack on the outboard half of the left wing deepened the stall on that side accelerating the wing drop.

There was no snap roll associated with this event and yaw was still minimal. All that was required was to reduce power to idle, neutralize the ailerons and elevator, and add opposite rudder to halt further yawing motion.

The takeaway from this one is to use rudder to level wings during stall practice, not ailerons.

To learn more about the aerodynamics of stalls and spins, view the lesson entitled Stalls, Spins, and Spirals at the Gold Seal Online Ground School.

 

 

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