Cross controlled stall

[flyingron]

I demonstrated them in a Cirrus SR22. I was a bit nervous, so made sure I had at least 5,000' of altitude. Could not provoke anything at all scary, but apparently the same cuffed leading edge that makes them hard to spin can eventually be provoked into a spin quite rapidly if taken too far. Good example of that below...

Apparently not. Nothing in Berto's analysis indicates the split leading edge made things worse. He pointed out that sometimes even the split leading edge doesn't leave the ailerons in the non-stalled territory. Further the abrupt control input didn't cause a spin but a sharp acceleration (snap roll) in the other direction. Attached is the accident report.

 

[Dana]

Good question. While most planes recover pretty easy from a 'slipping' stall as opposed to a 'skidding' stall but not all. I've heard you can lose a Lear pretty quick.

Hmm. That said "...A skidding cross-control stall..." Up there at the top. Skidding ain't cross controlled. Skidding is both aileron and rudder in the same direction but to much rudder or not enough aileron. Slipping is cross-controlled.

As some others pointed out a skidding turn is indeed cross controlled. The combination of the downward deflected aileron on the inside plus the fact that the inside wing is moving slower sets it up to stall first, with a spin likely.

In a slip, you're also cross controlled, but you're not turning so the "slower inside wing" factor isn't present, and unlike the skidding base to final turn scenario, it's usually done intentionally with the nose down.

I really don't understand why so many pilots are frightened of exploring things like cross controlled stalls, etc. Most trainers, even if they're not approved for spins, are hard to get into a spin and will come out quickly with neutral controls if the spin isn't fully developed*. I occasionally go up to a safe altitude and just thrash the airplane around in a deliberately sloppy manner just to see what it will do. But I'm one of those guys who enjoys spins, too.

*To be approved for intentional spins, an airplane must, among other things, recover from a six turn spin in no more than 1½ turns. If it recovers reliably in 1¾ turns, it doesn't get the approval. If the airplane is not to be approved for intentional spins, it still must be able to recover from a one-turn spin or a three-second spin, whichever takes longer, in not more than one additional turn after initiation of the first control action for recovery.

In a Cirrus, of course, the approved control action is "pull the red handle"

 

[luvflyin]

Sometime I think these argument do more damage than good. How about this:

The demonstration maneuver called a "cross-controlled stall" in the AFH is designed to simulate the classic overshoot base-to-final stall/spin scenario. The entry is a normal banked turn to final but same direction rudder to "help" bring the tail around more quickly. So same side - the entry is a skid. The result is, the nose lowers and the bank steepens. Back pressure to bring the nose up and opposite aileron (cross-controlled) to lessen the bank combine to induce the uncoordinated stall.

Gotcha. You will be putting 'cross inputs' to the controls. Ergo, cross-controlled. If turn is to the left, putting in left rudder, then adding in some right aileron to keep the bank from increasing. I was looking at it from the standpoint of a slip, where you have your left foot to the floor and the yoke cranked to the right, and holding it. Can't get much more cross-controlled than that. I see your point about thinking a skid is not cross-controlled just because you have left rudder in and the wings are still banked to the left could dangerous thinking. Am I describing it pretty well, or still missing something?

 

[brcase]

I only made it about 1/2 way through the thread so perhaps already answered.

would it be incorrect to recover once the stall warning is heard?

What does the PTS say you need to do?

For you CFI Training/Checkride and then future training provided you are going to have to know how to read them. And they change with some frequency.
When to recover from the stall wording has changed several times over the past 10 years for various checkrides and will likely continue to change.

Now I am off to the CFI PTS to see what it actually says, you should get used to doing the same.
I will likely be back shortly with the quote from the PTS.

 

[luvflyin]

As some others pointed out a skidding turn is indeed cross controlled. The combination of the downward deflected aileron on the inside plus the fact that the inside wing is moving slower sets it up to stall first, with a spin likely.

In a slip, you're also cross controlled, but you're not turning so the "slower inside wing" factor isn't present, and unlike the skidding base to final turn scenario, it's usually done intentionally with the nose down.

I really don't understand why so many pilots are frightened of exploring things like cross controlled stalls, etc. Most trainers, even if they're not approved for spins, are hard to get into a spin and will come out quickly with neutral controls if the spin isn't fully developed*. I occasionally go up to a safe altitude and just thrash the airplane around in a deliberately sloppy manner just to see what it will do. But I'm one of those guys who enjoys spins, too.

*To be approved for intentional spins, an airplane must, among other things, recover from a six turn spin in no more than 1½ turns. If it recovers reliably in 1¾ turns, it doesn't get the approval. If the airplane is not to be approved for intentional spins, it still must be able to recover from a one-turn spin or a three-second spin, whichever takes longer, in not more than one additional turn after initiation of the first control action for recovery.

In a Cirrus, of course, the approved control action is "pull the red handle"

I get the thing about the inside wing in a turn, following a tighter radius, will be slower and therefore reach critical angle of attack before the outside wing. But wouldn't that happen even if you are coordinated? I've done stalls, straight ahead, in a foot to floor slip, and the 'high' wing stalls first. No turn, so no 'inside' wing. I still must be missing something.

 

[midlifeflyer]

Gotcha. You will be putting 'cross inputs' to the controls. Ergo, cross-controlled. If turn is to the left, putting in left rudder, then adding in some right aileron to keep the bank from increasing. I was looking at it from the standpoint of a slip, where you have your left foot to the floor and the yoke cranked to the right, and holding it. Can't get much more cross-controlled than that. I see your point about thinking a skid is not cross-controlled just because you have left rudder in and the wings are still banked to the left could dangerous thinking. Am I describing it pretty well, or still missing something?

Exactly. I think that because the wing is banked left we get the mental picture that left aileron is being used. But we are actually puting in right aileron to maintain the medium bank. The better picture is a normal turn where the ailerons are neutral after the turn is established or a steep turn where we need opposite aileron to prevent overbanking.

I'm not at sure it's helpful to think in terms of slip or skid at the point of the stall. A transition is taking place and ultimately, unless recovery is initiated we are dealing with an uncoordinated stall, whichever rudder is being used.

 

[dmspilot]

That said "...A skidding cross-control stall..." Up there at the top. Skidding ain't cross controlled. Skidding is both aileron and rudder in the same direction but to much rudder or not enough aileron. Slipping is cross-controlled.

The cross-controlled stall demo that the FAA wants is a skidding stall. It's not a typo.

 

[luvflyin]

The cross-controlled stall demo that the FAA wants is a skidding stall. It's not a typo.

Yeah. I'm getting that now. I'll add an edit to my post saying I got this wrong and to read on.

 

[luvflyin]

In a skidding turn, too much rudder is being used in the direction of the turn, while aileron is being used in the opposite direction to prevent banking. Sounds cross-controlled to me.

This from a spin sequence in Stick and Rudder:

Yeah. I get that now.

 

[Dana]

I get the thing about the inside wing in a turn, following a tighter radius, will be slower and therefore reach critical angle of attack before the outside wing. But wouldn't that happen even if you are coordinated? I've done stalls, straight ahead, in a foot to floor slip, and the 'high' wing stalls first. No turn, so no 'inside' wing. I still must be missing something.

The slower inside wing is just one of many contributing factors. The down aileron is a larger factor.

 

[brcase]

Ok, that was fairly quick.
I see that the PTS is a bit vague on this particular maneuver.
Here were the pertinent parts I read about the stall/recovery.

b. Failure to establish a cross-controlled turn and stall condition that will adequately demonstrate the hazards of a cross-controlled stall.
c. Improper or inadequate demonstration of the recognition and recovery from a cross-controlled stall.
d. Failure to present simulated student instruction that emphasizes the hazards of a cross-controlled condition in a gliding or reduced airspeed condition. FAA-S-8081-6D 80 Change 6 (4/19/2018) 3. Demonstrates and simultaneously explains a cross controlled stall, with the landing gear extended, from an instructional standpoint.

So I can see why you may have asked, Best answer is call you favorite examiner and see what he says. I call mine several times a year even after instructing for 20+ years.
It may be a bit dependent on your airplane.
But the point I see is you need to demonstrate how a cross control stall is different than a coordinated stall.
if you can demonstrate that stall warning behaves differently when cross controlled vs coordinated that might be adequate.
Personally I would rather demonstrate why they are so dangerous with one or both of the following scenerios.

The skidded downwind turn to base scenario (or final if landing downwind). Left wing down, right Aileron, left Rudder, At altitude simulate a skidding turn that a Pilot may inadvertantly do in a low altitude downwind turn. Show how the plan stalls at a much lower Pitch angle than it does with a coordinated turn. I would demonstrate to 1st aerodynamic indication of stall (not stall warning)

The Slipping/over the top stall. like Left Wing down, Left Aileron, Right Rudder, i.e. Cross control a bit the other way and demonstrate how you can make the opposite wing stall 1st. Stall warning isn't going to show you the up wing stalling and dropping.

Brian
CFIIGASEL

 

[HF17]

I did a cross controlled stall today. The wing actually never dropping I kept applying more rudder and opposite ailerons and continued to pull back, but it just kept buffeting


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[HF17]

For some reason, when I do cross controlled stalls in the piper warrior, I cant get a wing drop. Does a wing have to drop for it be satisfactory on the checkride? My only thought is that maybe I’m not uncoordinated enough


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[Daleandee]

DPE Joe Casey gives a good explanation of the difference between a slip and a skid along with a nice visual presentation. (Starts at 3:30) ...

 

[midlifeflyer]

For some reason, when I do cross controlled stalls in the piper warrior, I cant get a wing drop. Does a wing have to drop for it be satisfactory on the checkride? My only thought is that maybe I’m not uncoordinated enough


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Mine didn't drop. I'm not aware of anything in the CFI PTS or the AFH description of it or any stall maneuver that requires a wing drop. Just a stall and recovery.

 

[HF17]

Mine didn't drop. I'm not aware of anything in the CFI PTS or the AFH description of it or any stall maneuver that requires a wing drop. Just a stall and recovery.

Ok. The PTS doesn’t say that there needs to be a wing drop, but I thought that the whole purpose of the maneuver is to demonstrate how cross controlled stalls are bad and could lead to spins. I feel like if I were to demonstrate a cross controlled stall that breaks evenly, the student might get the impression that cross controlled stalls are safe


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[dmspilot]

Ok. The PTS doesn’t say that there needs to be a wing drop, but I thought that the whole purpose of the maneuver is to demonstrate how cross controlled stalls are bad and could lead to spins. I feel like if I were to demonstrate a cross controlled stall that breaks evenly, the student might get the impression that cross controlled stalls are safe

The FAA cross controlled stall is a poor demo for that reason, so I don't do them with students. If you want to show them what not to do, a power-on stall with no right rudder does the trick.