In my primary training, a long time ago now, I read Kershner to learn how to fly. I trained in a skipper and one of the basic exercises was to fly at minimum controllable airspeed, hanging in the buffet, and maneuver, shallow turns using only the rudder. We also only used the rudder in the stall, recovery is aileron neutral, stay coordinated and step on the wing that drops if it drops. Now I read to use coordinated aileron and rudder to counter the wing drop. Which I guess is ok for a blended wing like a cirrus, but was a no no for a plane like a skipper, where using the ailerons at a stall contributed more adverse yaw than wing leveling and could cause the situation to worsen.
I will say, that I was doing stalls in an SR-22 and one of the stalls the left wing dropped on me, not expected, (I was coordinated). The drop was quick, I stomped on right rudder, while unloading the wing, and the airplane snapped level. I suppose that's the law of primacy, but it worked.
Anyway, maybe some of you aviation experts can chime in, but I always thought that in a skidding turn, you are skidding away from the center of radius of the turn you are trying to make, so why do it on purpose?
I was taught the same way by an instructor who learned to fly in WWII. But it's a dated method that wasn't always properly contextualized, fully understood, or properly applied.
Per the "pick up the wing with the rudder" theory, if you try to pick up a low wing with aileron at high angles of attack (AoA) near a stall, you are lowering the aileron on that wing, which effectively lowers the trailing edge of the wing in the section with the aileron. That then effectively lowers the rear of the chord line, which increases the angle of incidence, and thus increases the AoA, and thus *theoretically* could cause a stall on the low wing, making things worse instead of better.
In *practice*, there's a lot more going on. Many aircraft designs use some washout in each wing (slightly less angle of incidence at the wing tips) to help keep the outer portion of the wing flying at a slightly lower angle of attack than the inboard sections, and thus help maintain aileron effectiveness as the inboard sections of the wings will stall first. You'll also find slots or slats on the outboard sections of some wings (Stinson, L-5 etc) to keep the airflow attached on the outboard section of the wing to maintain aileron effectiveness.
In addition, wing planform matters. With a straight Hershey bar planform wing (think Cherokee 140, Piper Cub, Aeronca Champ, Citabria, etc), the wing roots stall first, which disturbs the air over the horizontal stabilizer and elevator (or stabilator in the case of the Cherokee series) and gives stall warning in the form of buffeting while the outboard sections of the wings are still flying and thus still giving you good aileron control. (Adding a Toblerone candy bar shaped stall strip on the inboard section of the wing will give you even earlier warning in the form of buffeting before the stall occurs over the inboard section of the wing as well.)
However, pretty much every other wing planform will either stall from the center of the wing and progress both inboard and outboard over the wing, or stall in the outward sections first and progress inboard. (See below). That's where washout and things like stall strips become even more important and more common. You'll usually find both on a tapered wing to curb that outboard to inboard stall progression effect. (Semi-tapered, tapered, and in particular elliptical wing planforms offer improved lift distribution and efficiency, which is why they are used, but they are also progressively more expensive to produce.)
Still, with all of that said, the "pick up the low wing with rudder" theory is that if you apply enough aileron trying to pick up a low wing at high AoA, you will stall the outboard section of that wing and make the situation worse. The theory continues that if you ignore your instinct to pick the wing up with the aileron and instead pick it up with opposite rudder, you will instead advance the dropped wing into the relative wind and increase the airflow over the wing, increasing it's lift.
That's also where the theory runs off the rails, due to the interaction between yaw and dihedral angle in the wing. When the wings have dihedral angle (or alternatively wing sweepback), the yaw caused by applying opposite rudder to "pick up" the low wing increases the AoA of the advancing wing and decreases the AoA of of the retreating wing. The greater the dihedral angle (or sweepback angle) the greater the rolling effect created by yaw. If you've ever flown a single channel, two channel or 3 channel R/C aircraft where you have no aileron control, you understand the concept. If you ever (successfully) designed your own no aileron R/C aircraft, you also understand the interplay between vertical fin area and dihedral angle to keep those no aileron turns coordinated.
Consequently, the "pick up the low wing with rudder" theory works by increasing the AoA on the low wing (which advanced when opposite rudder is applied) and reducing the AoA on the high wing (which retreats when opposite rudder is applied), rolling the aircraft back to level flight - provided the wing has dihedral angle (or wing sweep).
However, the "pick up the low wing with rudder" theory comes up short in two areas:
1) If you are picking a low wing up with rudder in an aircraft with substantial dihedral angle, you are actually increasing the AOA over the entire wing - and could potentially stall that wing with aggressive enough rudder input at a high enough angle of attack; and
2) the theory only works if the low wing is still flying and sufficiently below the critical AoA so that increasing the AoA does not cause it to stall. In other words it works ok in slow flight *approaching* the critical AoA, but WILL make things a lot worse if applied at or just below the critical AoA by causing or deepening the stall on that wing.
Which takes us to the current thinking on the issue....
The critical action to take in a stall is to reduce the angle of attack to get the wing flying again. In the old days, the FAA's standards focused on minimizing altitude loss (50' IIRC), which led to some pilots developing the bad habit of cramming on lots of power and flying their way out of the stall, while giving up as little back pressure as possible. That works fine in something like a Supercub, but it works a lot less fine in something like a 285 hp V35 Bonanza, where the torque of the engine combined with the small V tail creates a Vmc that is higher than the stall speed. Full power applied at or just above stall speed gets really interesting really quick and leaves you looking straight down at the ground when you run out of both rudder and aileron and depart over the top.
Not just coincidentally, I learned to fly in a Supercub 150 and developed that habit of flying out of a stall with basically no altitude loss. I had an instructor during my commercial work ask me for a left hand turn using full right rudder and right aileron. I had to think about it a few seconds, before adding full power, and slowing down until I had full right rudder and some sight aileron applied, and had the aircraft ( a 285 hp V35 Bonanza) turning a steep climbing left hand turn. He then told me to hold it in that climbing turn and stall it. I learned a lot in that stall as I departed/snapped over the right wing and found myself looking almost straight down.
So...my understanding is the current thinking is focused on the critical action of reducing the AoA to get the wings flying again. Then, once the wings are flying, use coordinated rudder and aileron to get the aircraft level again. My understanding is that there's now less focus on minimum altitude loss, and more emphasis on breaking the stall and staying in coordinated flight to avoid the potential for a secondary stall and spin. It strikes me as a very positive change.
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The thing I struggle with a bit is the FAA perhaps over applying the "normalization of deviance" concept and not wanting pilots to demonstrate slow flight with the stall warning horn activated. That's based on a fear that they'll get used to it, think the stall warning horn is "normal" and ignore it at a critical time. (But it should be normal - on each and every full stall landing.)
On most light aircraft no stall warning horn in "slow flight" leaves you at least 5 kts above a stall, and on many aircraft it's closer to 10 kts (or more). That's far enough away from a stall that I worry that student pilots may not fully grasp or appreciate things like rapidly increasing induced drag and what it feels like and means to be way behind the power curve, or the nuances of slow flight such as the potential for reduced aileron effectiveness in some aircraft (and in particular with some higher performance wing planforms) as you approach the critical angle of attack. I suspect the pendulum may swing back in the other direction when we've eventually had a sufficient number of accidents caused by what
wasn't learned.
