Keeping the wings level in a stall

[Pilot DAR]

I would like to receive experiences and opinions on the techniques taught and used for keeping the wings level during deliberate approach to a stall.

It has become apparent to me that the technique I have been taught, and practiced in many types over many years, is not universal. I am required from time to time to stall different aircraft as a part of evaluation of their flight characteristics. When flying alone, I employ the technique I have been taught (it's kinda instinct now), and which has been reinforced to me by those who oversee what I do. However, on occasion, I am conducting stalls in the company of other pilots, and even with preflight briefing, find that some of those pilots use techniques which differ considerably from mine.

Though the wisdom of the experienced pilots is valuable, the new pilots here are equally important, as they have just received the training, and perhaps do not yet have "habits" overlying that training yet!

Tell me how you keep the wings level, and why you do it that way...

Thanks, Jim

[vanHorck]

I keep the ball in the middle with rudder input and gently release rudder pressure as I reapply power

[Captain Smithy]

Use rudder to keep wings level/ball centered, never use aileron near or at the stall (unless you want to spin :uhoh:)

[FlyingStone]

As said, gentle movements with rudder to keep the ball centered (this is actually the most important thing), ailerons in neutral (try not doing so in proper stall training aircraft, e.g. Tomahawk and you'll see why), the elevator is in a position for required angle of attack.

As for recovery, full throttle isn't optional, speed of releasing (and pusihing) the stick varies from instructor to instructor. On proper aircraft it is neccessary to push the stick forward a little in order to brake stall, but for C172-like it is enough to just release stick and the nose drops. In my opinion, nose should be lowered (and thus reduced AoA) as quick as possible, disregarding of passengers feelings (as one of my instructors said, stall recovery should be slow and smooth), since stall isn't really state of aircraft I'd like to be in with aircraft full of passengers.

[Flyingmac]

The technique employed can be type-specific. For example, one (modern) type I fly has effective ailerons right through into the stick hard back, fully stalled state, but be wary of any rudder input. So, horses for courses.

[Mark1234]

Rudder.. though mishandling that may (a/c dependent) tend to pitch one into rotation, as much as aileron missuse may on others. Also, in my experience, once fully stalled, it can be remarkably difficult to enter the spin, even when you're trying!

As for breaking the stall, I'm firmly of the stick and more stick principle. Primacy perhaps as I learned on gliders, but the 'minimum height loss' - pitch level and apply power technique really irks me. Fly the wing; it can be stalled or unstalled at any attitude. That said, there is no need to be violent, just positive.

[NigelOnDraft]

My 2ps worth...

Keeping the wings level in a stallWhy do you want to? Is that really important / a priority?

2 priorities are:
1. Unstall the wings - only now do you have "control" of the aircraft.
2. Minimum Ht loss in the whole stall / unstall / climb cycle.

1 is achieved by reducing the AoA. Not "pushing" the stick, but relaxing back pressure / easing it (centrally) forward until the wing is unstalled and no more. The moment the wing is unstalled, you have ailerons to level the wings.

2 is achieved by:
a. Only lowering the AoA until the wing is unstalled, and not "shoving" the stick forward.
b. Power
c. A prompt ease out of "dive" and into a climbing attitude (without further stalling the aircraft).

Clearly some teaching / types concentrate on the rudder - fine, if that is on good authority (in authorised manuals) - but I cannot recall seeing it on types I fly.

The aim is a simple repeatable drill that is being practiced for a stressful / hazardous situation. Rudder in the stall might work for a TP, but can also provoke a spin if used incorrectly, so IMHO not a good tactic. A prompt reduction in AoA as priority #1 will minimise any wing drop...

As a (Q)FI on various types (SEP, Jet) the usual technique errors I observe / debrief / re-practice on are excessive stick forward / nose down attitude, and then far from optimal transition back to a climb e.g. lose more height / eventually climbing 10K+ above what could be achieved.

NoD

[M14_P]

Why would you want to? Simple, to execute a falling leaf, in a Tiger anyway. Great fun and a great challenge.

[Pilot DAR]

Perfect, more contributions please. Keeping the wings level to the greatset extent possible through the stall is the objective....

[englishal]

I was always taught to keep the aircraft balanced but DON'T try to pick up a wing in the stall using rudder. Simply unstall and then worry about wings level.

[Cows getting bigger]

It depends upon what you are trying to achieve. Firstly, you initially talk about the 'deliberate approach' to the stall so, in the early stages (for argument's sake pre-stall warner), I would continue with the ailerons. At the later stages, the key bit is to keep the controls centralised and remain balanced (ball). As this is an exercise, if you have an unintentional roll at this point onwards, I would recover pre-stall. Conversely, if you are attempting to generate/demonstrate a wing drop then continue as suggested above.

In you last post you talk about the objective being to keep he wings level throughout the stall. Can I presume this means you stall the aircraft and are not seeking immediate recovery? Instinct tells me that, in general terms, pilots shouldn't be fiddling with any of the aircraft controls (aileron/rudder) during a stall unless they are trying to achieve something other than recovery. Under such circumstances, the actions are very dependent upon aircraft type.

[IO540]

In the PA38 Terrorhawk I was taught to use the rudder to keep the wings level; apparently the ailerons were ineffective during a proper stall and could cause a spin...

Otherwise, I use the ailerons to keep the wings level, and use the rudder to keep the ball in the middle because yaw during a stall is potentially bad news.

Certainly on the TB20 this is fine; it does everything it says on the tin, with no suprises, ever.

Recovery is a smooth re-application of power, back to the cruise setting, together with moving the yoke forward, so one recovers to cruise speed without any real loss of altitude (under 100ft). In the FAA IR they get you to do this partial panel ;)

Obviously an emergency recovery would use a bit more power than that :) but if you quickly whack the throttle fully forward you suddenly have a lot of yaw to deal with; don't try this in a TBM, evidently...

[englishal]

Otherwise, I use the ailerons to keep the wings level, and use the rudder to keep the ball in the middle because yaw during a stall is potentially bad news
This is also fine in my Rallye where I can use the ailerons even when completely stalled and falling with style. However the input of aileron on some types can increase the stall to one wing (the down aileron side) due to the increased AoA on that wing and so likely if you tried to pick up a wing this way in some aeroplanes the aircraft would just roll more towards the wing-down side and you may well depart into a spin. I know you know this but I'm pointing it out for the benefit of the audience :}

[RatherBeFlying]

I remember being checked out in the C-172 after getting my license in the C-150.

The instructor stalled it; then with the stick all the way back, flopped the ailerons back and forth from stop to stop -- wings stayed level.

The glider checkout instructors seem to get a bit miffed when I use rudder to stay coordinated approaching the stall:confused:

[A and C]

The rudder should be used to STOP the yaw this should prevent wing drop.

Rudder must NOT be used to "pick up" a wing only to prevent further wing drop.

Stall + Yaw= Spin!

[bjornhall]

The only way to create a rolling moment with the rudder is to induce a sideslip. Rhetorical question: Would we rather stall in coordinated or uncoordinated flight?

The scenario: Reduce the airspeed, add back pressure, ailerons neutral, apply rudder pressure. I just described entry into a spin. To me it sounds a bit peculiar to have this scenario described as the proper way to prevent a spin.

What I was taught, and use, is to apply slight, smooth aileron inputs to keep wings level, using rudder for coordination. At the stall, ailerons neutral and use rudder to counter any yawing tendencies. If a wing drops at the stall, e.g. if one uses too much aileron or flies a plane that does have a tendency to stall over a wing, then that is just the way it is; it will be a stall with a wing drop. Recovery from a stall with a wing drop is something we all learned during training, right...?

Even if one uses too much aileron and provokes a wing drop, a spin should not result provided one uses rudder to counter adverse yaw and maintain yaw control.

Apart from my training, both standard references I use for basic flight procedures and techniques (the FAA's Airplane Flying Handbook and John S. Denker's See How It Flies) suggest coordinated use of aileron and rudder to maintain wings level during the approach to stall.

Nevertheless, intrigued by what I have been reading here in the last few years, I decided to go up and try the "keep wings level using rudder with ailerons neutral" approach to see for myself. I used a C172. After some rather spectacular departures for a C172 :E I decided it was just as bad an idea as I thought before I tried it.

The problem with that method, IMV, is what happens if it fails. If you manage to keep the wings level with small inputs, i.e., do not have to try and catch a wing that shows a tendency to drop with either rudder or aileron, both methods work. But if you fail, the coordinated aileron method results in a rather benign wing drop, whereas the rudder only method results in an incipient spin.

[Big Pistons Forever]

I would suggest you should approach this question from a different direction.
Assuming we are not talking about aerobatic training, I think it is imperative that one does not think about the stall entry as a stand alone exercise. There is no reason the aircraft should stall at altitude. If the aircraft has stalled than the guy/gal at the controls has seriously screwed up and if close to the ground this is a full blooded emeregency. Therefore it is vital that the instinctive reaction of the pilot to a stall is to lower the nose to unstall the wing and to simulataneously use all necessary rudder to stop the aircraft from yawing thus making it impossible for it to enter a spin. In training the worse the stall entry the better as if the student can reliably recover from a banked yawed entry than they will be well prepared if they ever get cought for real. Finally the best recovery from a stall is to not stall in the first place therefore training to recognize the condition which indicate a potential stall is possible is just, if not more, important than stall recovery training. Stall entry training is simply a necessary precursor to learn the real lesson, stall avoidance and recovery, and should never IMO be presented as an exercise in itself.

[barrow]

Why has no one specified what type of stall they are doing, power on, off, accelerated?
In most single trainers, doing a power on departure stall, you will most certainly drop a wing at the break of the stall if you kept the ball centered and the wings level during entry, does anybody know why.

[24Carrot]

...the best recovery from a stall is to not stall in the first place...

Applying that principle to engine failures would have eliminated one of the longest current threads on pprune!

[Cows getting bigger]

barrow, consider the relative airflow generated by the propeller in a power-on stall.

[englishal]

In most single trainers, doing a power on departure stall, you will most certainly drop a wing at the break of the stall if you kept the ball centered and the wings level during entry, does anybody know why.
Torque, slipstream and P Factor all spring to mind.

[Pilot DAR]

The point of my question was the technique used to fly the aircraft to demonstrate compliance with the certification requirement (either power on or off) that it be possible approaching and throughout the stall to maintain the wings within 15 degrees of level, with normal use of the controls.

We do it at altitude, 'cause it's safer up there. I agree that there is no good reason to do this in "regular" flying, other than training, or flight test.

CAR 3.120 (c):

....and not more than 15 degrees roll or yaw shall occur when controls are not used for 1 second after pitch starts and are used thereafter only in a normal manner.

During flight testing I have done with other pilots in the past, who have suddenly decided to "help" me with the stall recovery during such demonstrations, I have seen the ball hard over (where I had been carefully keeping it centered) when the other pilot applied a boot full of rudder. This un-nerves me, as being rather close to a speed at which a stall or spin could be expected, the last thing I feel comfortable with is seeing the ball hard over. To me, that is spin entry territory, and a spin is not the objective.

I have reviewed the 22 different flight manuals in my library today. None mention the use of rudder during a stall. A few mention the normal use of ailerons. Many just refer to recovering (with no stated technique), and a couple do not mention stalls at all. The FAA flight test giude requires the "normal" use of controls. I hold the opinion that the use of rudder (without accompanying aileron) to un co-ordinate level flight at any speed would not be normal use of controls.

So with the certification requirements requiring a demonstration of wings level with "normal" use of the controls, what would be the basis of training not to use ailerons during the approach (be it deliberate, or suddenly recognized) to a stall? Is the rudder only technique written somewhere?

[lonewolf46]

Given the various types of stall available, from your basic straight level through to fully inverted stalls along with steep turns keeping the wings level is irrelevant. After the stick back pressure has been released part of the recovery is to get your wings level as the angle of attack is relaxes then power on and climb. There was an excellent article in Australian Flying about 5 years ago on the "stall stick theory".

For those that really want to stall grab yourself an instructor climb up to 4500agl slow down to just above stall, reef the stick back as far as your can cleanly then kick in a full boot of rudder and enjoy the ride, i repeat dont try this without an instructor.

[bingofuel]

the last thing I feel comfortable with is seeing the ball hard over. To me, that is spin entry territory, and a spin is not the objective.

Yes, but the stall will occur first and provided you recover from the stall the spin will not develop.
In a perfect aeroplane with perfect rigging, flown perfectly in balance with no propellor effects, both wings will stall at the same time and a wing would not drop.
As these conditions will not exist, if you want the aircraft to stall both wings at the same time, I would suggest that the rudder is used to prevent or induce a yaw to try to cause each wing to stall at the same time. To achieve this may well involve the balance ball not being centered but the result is each wing will stall at the same point due to all the variables being equal.

[barrow]

barrow, consider the relative airflow generated by the propeller in a power-on stall.Nothing to do with a wing drop in a stall.

Torque, slipstream and P Factor all spring to mind.Then why does everyone keep the ball centered to the stall, then wonder why the wing drops!

bingofuel

Yes, but the stall will occur first and provided you recover from the stall the spin will not develop.
In a perfect aeroplane with perfect rigging, flown perfectly in balance with no propellor effects, both wings will stall at the same time and a wing would not drop.
As these conditions will not exist, if you want the aircraft to stall both wings at the same time, I would suggest that the rudder is used to prevent or induce a yaw to try to cause each wing to stall at the same time. To achieve this may well involve the balance ball not being centered but the result is each wing will stall at the same point due to all the variables being equal. bingofuel gives the right answer, You want to stall and keep the wings level throughout recovery, don't center the ball, less right rudder and a slip is needed.
Ailerons are used for roll control and rudder for yaw. Using rudder alone to keep wings level during entry is poor form.

[Mark1234]

Ailerons are used for roll control and rudder for yaw. Using rudder alone to keep wings level during entry is poor form.

I'd suggest that's a massive oversimplification. Take a look at secondary effects of controls, and (I don't know if this is taught powered - it wasn't when I converted to spamcans), how the primary and secondary effects change (actually swap over) with speed.


Yes, but the stall will occur first and provided you recover from the stall the spin will not develop.
In a perfect aeroplane with perfect rigging, flown perfectly in balance with no propellor effects, both wings will stall at the same time and a wing would not drop.
As these conditions will not exist, if you want the aircraft to stall both wings at the same time, I would suggest that the rudder is used to prevent or induce a yaw to try to cause each wing to stall at the same time. To achieve this may well involve the balance ball not being centered but the result is each wing will stall at the same point due to all the variables being equal.

Arguably, a 'proper' spin doesn't exist until something like a whole turn or more - however, that's probably moot to this discussion, and a little purist.. but I do wonder how many are posting 'this will spin' know so from practical experience, or are just repeating - sometimes, aeroplanes can be surprising things:

Take a decathlon, establish a full sideslip, either way, rudder on stop, and opposite aileron/wing down to hold a straight line. Slow up until it stops flying, and the result is?

A (repeatable) clean, straight ahead stall with no wing drop? Who'd guess?
I wouldn't extrapolate to all a/c, particularly as the decathlon has a convenient straight, high wing with next to no dihedral. No matter the angle the wing is travelling, all parts are meeting the air at the same angle and speed. Why would one end stall first?

Personally I'm inclined to believe any static yaw is distinctly secondary to *rate* of yaw in determining wing drops. Obviously sweep and dihedral make yaw matter more.

BTW, those 'perfect' conditions do exist, It's called a glider :E

[bjornhall]

Yes, but the stall will occur first and provided you recover from the stall the spin will not develop.
In a perfect aeroplane with perfect rigging, flown perfectly in balance with no propellor effects, both wings will stall at the same time and a wing would not drop.
As these conditions will not exist, if you want the aircraft to stall both wings at the same time, I would suggest that the rudder is used to prevent or induce a yaw to try to cause each wing to stall at the same time. To achieve this may well involve the balance ball not being centered but the result is each wing will stall at the same point due to all the variables being equal.


You are closer to a spin if you stall with wings level and a side slip than if you stall with a wing drop and no side slip.

Spin requires stall, departure (i.e. none or negative roll damping, i.e. uncontrollable roll) and yaw (e.g. side slip). If you set up a side slip before the stall in a misguided attempt at preventing a wing drop you are already one step closer to the spin, especially keeping in mind that a side slip will lead to the wing drop. The departure/wing drop also leads to a yaw eventually, but that yaw tends some time to build up.

By recovering from the stall after the wing drop but before the yaw builds up you will prevent the incipient spin from developing. Doing it the other way around, recovering after the yaw but before the wing drop, will not be likely to work.

In my admittedly limited experience, yawing/side slipping at the stall will always lead to a wing drop before the stall recovery, but a wing drop at the stall will not lead to significant yaw or an incipient spin. I know (as in have been told that) some planes will always produce a yaw after the wing drop before stall recovery is complete, but I do not believe there are many planes where a wing drop produces yaw but where a yaw does not produce a wing drop. Consequently, preventing the yaw is always the number one priority to avoid an incipient spin, whereas preventing a wing drop is the second priority.

For Pilot DAR's test flights, I don't suppose the testing criteria will be met if he stalls with wings level and a side slip... :8

As for why the wing drops: Preventing a wing drop does not necessarily require that both wings stall at exactly the same time! Some roll damping can still remain even if pitch stability is lost. This is because roll damping is primarily provided by the outboard parts of the wing, whereas pitch stability and vertical damping is provided by the entire wing. If the inner wings are sufficiently stalled for vertical damping to be lost (i.e. the aircraft settles straight ahead) or pitch stability to be lost (i.e. the nose drops) while the outer wings are sufficiently unstalled for roll damping to remain, the aircraft will not drop a wing. That is how modern aircraft are designed.

If preventing a wing drop was dependent on both wings stalling simultaneously, it would be a rare exception that an aircraft would stall without a wing drop. That is not how it works at all. It is the roll damping that prevents the wing drop.

In other words, maintaining aileron effectiveness during a stall is a secondary reason why we always want the inner wing to stall first. The primary reason is to maintain roll damping during the stall. Preventing a wing drop by having ailerons effective but no roll damping, thus relying on the pilot to balance the plane and actively prevent a wing drop, would be very hard and rarely successful. Preventing a wing drop by having remaining roll damping is automatic, the pilot doesn't have to do anything. Roll damping during a stall is the most important thing; aileron effectiveness is secondary.

And contrary to what a previous poster said, the airflow generated by the propeller has everything to do with why a wing can tend to drop at the stall; at least it is one of the most important factors. For example, the helical prop wash hits the two wings at slightly different angles of attack, tending to cause them to not stall at the same time near the roots. If sufficient roll damping remains, this will still not result in a wing drop, but if there is insufficient roll damping then this assymetrical slip stream effect is one of the reasons why a wing will drop.

On the relation between roll damping and use of aileron: Roll damping is what stops a roll if it develops; aileron control is used a return the wings to level after the roll damping has damped out any roll disturbance. If roll damping is so low that the pilot actually has to balance the wings using continous aileron input, the pilot will most likely not succeed for very long and this will cause a wing drop. If the pilot tries to achieve the same thing with rudder, the risk of over controlling is much greater (since the rolling moment is a secondary effect to rudder input, after a yaw has already built up), and the result if one fails are much more dramatic.

Again: Attempting but failing to keep the wings level with rudder results in all three pro-spin factors to be present; stall, yaw and roll. Attempting but failing to keep the wings level with aileron only results in two factors to be present: stall and roll. In the latter case, recovery can be made before the yaw builds up.

Edit: Forgot to point out that when I mention "aileron input" I of course mean coordinated aileron input! As always (except possibly in cruise in some aircraft...) when the aileron moves the rudder should move as well. But this rudder movement is not intended to cause a yaw but to prevent a yaw. Getting that wrong and using only uncoordinated aileron will of course cause a yaw and a side slip and that will mess up everything. But this coordinated use of rudder to prevent the adverse yaw due to the aileron input is completely different from the uncoordinated use of rudder to cause a side slip with a secondary rolling moment.

[Whopity]

On flight tests you ask the candidate to demonstrate a stall. Invariably they close the throttle and make no attemt to compensate for the yaw caused by reducing the slipstream. Invariably, they apply some aileron to keep the wings level thus, if you hold the aircraft in the stall a wing is likely to drop.

As you approach the stall keep straight with rudder, never mind the ball, just look out of the window and pick a point in the distance. If you prevent yaw the wings will remain level until the aircraft stalls.

[barrow]

Mark1234
I'd suggest that's a massive oversimplification. Take a look at secondary effects of controls, and (I don't know if this is taught powered - it wasn't when I converted to spamcans), how the primary and secondary effects change (actually swap over) with speed.
What has "primary and secondary effects" got to do with stall entry? Nothing! and to mention it as a factor is just plain silly.

[barrow]

bjornhall (http://www.pprune.org/members/170028-bjornhall), 12 paragraphs of utter nonsense. the only part of your post that made sense was "In my admittedly limited experience"

Single engine trainers, (US) are built with a off center thrust line, higher angle of incidence on the left wing and a canted vertical stab to offset the LTT in cruise. When the AC is stalled with a centered ball, both wings have an unequal AOA at the moment of stall, this leads to wing drop.

[bjornhall]

barrow, just because you haven't understood something doesn't make it less true...

Go up in an airplane and do some experimentation on your own then. You should be able to discover that what you just said is not relevant to what actually happens.

There will be all sorts of asymmetries in any stall situation aside from the design asymmetries you mention; a small slip angle, a small gust at the wrong time, slightly unequal fuel or payload distribution, and so on. If such small effects were enough to cause a wing drop it would be a very rare event to see a straight ahead stall. But what happens in real life is that modern aircraft with sufficient washout etc tend to stall straight ahead every single time! The reason is that the roll damping catches the roll before it has time to develop, and only a very slight residual bank remains to recover. Therefore, contrary to what you say, the design asymmetries do not cause a wing drop, even if the ball is not held slightly off-center to compensate for the asymmetric thrust.

If you don't have sufficient roll damping for whatever of many possible reasons, you do get a wing drop if you have any asymmetry in the situation. But since the design asymmetries included to counter the LTT in cruise are just one example of such asymmetries, and there could very well be some other asymmetry at play (see examples above), trying to fly with exactly the right amount of off-center ball to counter the design assymetries would be a waste of time IMV. Indeed, if you would try that and get wrong the resulting side slip would cause a rolling moment due to slip roll coupling that could very well be far bigger than the design asymmetry you tried to compensate for in the first place.

The asymmetries you mention really are extraordinarily small. To provide slip free operation with one engine out in a twin requires a bank of a couple degrees or so. That is with the operating engine mounted all the way on a wing; how many thousands of a ball width will be required to offset the off center thrust in a light single? Not many!

BTW, you should probably be aware that trying to emphasize your points by insulting those you discuss with just might make you come across as a somewhat mentally challenged individual... Just thought you might know, to make a better first impression next time.

[stickandrudderman]

I'm not experienced at experimenting with the stall, but I had a trial flight in a pitts a couple of years ago where it was demonstrated how to descend in the stalled condition by keeping wings level with the rudder alone (stick fully back).
A boot full of rudder in this condition however would result in a flick roll.
At least, that's how I remember it.
I haven't tried it in a cirrus though!

[Mark1234]

I shall also assume good intent:

At normal flying speed, ailerons produce mostly roll, and some adverse yaw (secondary effect). The rudder produces yaw, and eventually roll (secondary effect). I'm sure you know that.

Near the stall, (i.e. at high angles of attack) the ailerons will produce a far more pronounced yaw, and reduced roll response. The rudder will produce less yaw, and a more pronounced rolling tendency. In some types you will find that at some speed near the stall, the secondary effect becomes the dominant. Not to mention the already made point that in many types, aileron use at the stall will create a wing drop in precisely the opposite direction to the roll 'commanded' by the ailerons. That may have nothing to do with stall entries, but it has everything to do with your assertion that:
Ailerons are used for roll control and rudder for yaw. Using rudder alone to keep wings level during entry is poor form.

Bjorn,

What you say makes sense to me in the main, but I didn't like the idea of the roll damping 'catching' the roll. Unless I'm mistaken, damping is just a resistance to movement (in this case the roll), an inertia if you like. It will not actively restore the wings level, rather make the aircraft less susceptible to the 'fine detail' level of the wings stalling *exactly* at the same time? I'd still suggest they need to stall substantially together.

I'm also interested in the definition of slip and particularly yaw. Does an aircraft in a stable, straight line sideslip have yaw? It definitely has slip, and I know the fuselage is not pointing in the direction of travel, but I'm inclined to suggest it doesn't have yaw, and if it does, it doesn't have a rate of yaw - all parts of the wing move at the same speed, and in terms of direction and space, it is not moving around the yaw axis. In a sense it's no different to an oblique wing NASA AD-1 - Wikipedia, the free encyclopedia (http://en.wikipedia.org/wiki/NASA_AD-1) flying in a perfectly straight line.

[Mad Girl]

I'm not experienced at experimenting with the stall, but I had a trial flight in a pitts a couple of years ago where it was demonstrated how to descend in the stalled condition by keeping wings level with the rudder alone (stick fully back).

At one point in my aero's training I didn't like spinning the Decathlon.... so my instructor and I approached it by getting me to hold in a fully developed stall, holding wings level with rudder (stick fully back), and not recovering until I'd descended 1500 feet.

We then clambered back up and tried again but allowing an incipient spin by letting the wing go....

I got there in the end, and managed my 3 turn spin and recovery...

[barrow]

bjornhall, Are you kidding me pal? Again 6 paragraphs of utter nonsense from you in an attempt to bolster a completely flawed conclusion.

[barrow]

Mark1234
At normal flying speed, ailerons produce mostly roll, and some adverse yaw (secondary effect). The rudder produces yaw, and eventually roll (secondary effect). I'm sure you know that.

Near the stall, (i.e. at high angles of attack) the ailerons will produce a far more pronounced yaw, and reduced roll response. The rudder will produce less yaw, and a more pronounced rolling tendency. In some types you will find that at some speed near the stall, the secondary effect becomes the dominant. Not to mention the already made point that in many types, aileron use at the stall will create a wing drop in precisely the opposite direction to the roll 'commanded' by the ailerons. That may have nothing to do with stall entries, but it has everything to do with your assertion that:Which types? please specify.

[Pilot DAR]

So, if there is merit to using the rudder (disproportionately to the ailerons)to control roll at low speed, and during the approach to a stall, why can I not find a flight manual which says this is the way to do it? I have to presume that if the flight manual says to use "normal" control inputs, or is silent on technique, that "normal" use of ailerons for roll, and rudder for yaw, is intended. Are there authoritative publications out there which describe these "rudder priority" techniques, or are they only training "hand me downs"? If so, from where?

I did about 30 minutes of stalls in a Grand Caravan today. All unacellerated, but all power and flap settings. When high power stalls were approached, a boot full of rudder was needed to overcome the torque, but the aircraft otherwise flew level and ball in the middle. When it broke in the stall, it went wings level, with only very slight aileron inputs to keep it so (the 208B POH is silent on specific stall handling technique).

So where do I find a document which describes the primary use of the rudder near the stall?

[polyfiber]

Keep the ball centered with the rudder. Don't pick up a wing with ailerons when stalled.

Proper stall recovery:

Push to unstall wing

Center the skid ball with rudder

Apply power and resume flight.

Applying power before unstalling the wing will cause a lot of torque roll, in some planes you will go inverted, Pitts, Midget Mustangs ect.
If you try to pick up the wing with aileron, when stalled, you will further stall the wing with the downward deflecting aileron. Remember your spin recovery practice? Trying to use aileron to roll out of the spin accelerates the rate of spin. The reason being that you are putting that wing with the downward deflecting aileron deeper into a stall.

[englishal]

It makes logical and aerodynamic sense NOT to use ailerons very close to the stall...We all know that ailerons change the AoA of the wings and so if you are happily flying at max AoA (say 17 degrees) on both wings, nicely balanced and you put an aileron input to the right, then the left wing AoA could exceed max AoA and the right wing could be below max AoA. In this instance the left wing will stall and the right wing won't. Using aileron to further try to pick up the left wing will exacerbate the situation and the roll will continue.

Doesn't happen very dramatically on a training aeroplane where the insides of the wings tend to stall before the outsides and you maintain aileron authority even into the stall but I imagine on something like an Extra with an asymetric wing the effect would be quite pronounced. Sometimes it helps get aeroplanes into a spin - one FI I knew used to spin the C150 by applying full power, full left rudder and full right aileron to ensure it entered the spin.

[bjornhall]

It makes logical and aerodynamic sense NOT to use ailerons very close to the stall...We all know that ailerons change the AoA of the wings and so if you are happily flying at max AoA (say 17 degrees) on both wings, nicely balanced and you put an aileron input to the right, then the left wing AoA could exceed max AoA and the right wing could be below max AoA. In this instance the left wing will stall and the right wing won't. Using aileron to further try to pick up the left wing will exacerbate the situation and the roll will continue.

We are into the fine tuning parts of the discussion here... ;) Everyone probably knows and agrees that a large aileron input close to the stall will often make that wing stall, and that an aileron in a stalled part of a wing will work in the reversed sense in that regard (aileron down on a wing will cause that wing to drop, not rise). I just do not agree that it is therefore a logical conclusion to not use ailerons close to the stall.

The argument against that conclusion is that in a wing with sufficient washout the part of the wing where the ailerons are mounted are not so close to the stall that they work in the reversed sense, even if the airplane as a whole is stalled (i.e. vertical damping and/or pitch stability is lost). Ailerons on modern certified aircraft (and on many others, although not all!) will work in the normal sense even in the stall, and certainly just before the stall. We just should not use sudden large aileron inputs very close to the stall, or try to pick up a wing that is already dropping using ailerons (if we already have uncontrollable roll due to loss of roll damping we will most likely have lost aileron control as well).

We don't have to use rudder and slip since we still have aileron control, and using ailerons is both a more efficient, faster and safer way of doing it IMV.

I think it is interesting to note that in the C172 the recommended control positions for spin entry is ailerons neutral or a slight aileron input into the spin (e.g. full right rudder and neutral or slightly right aileron into the right spin). Even in the spin entry the ailerons work in the normal sense.

Couldn't say how it works in an Extra.

[M14_P]

A&C, I dissagree there. Rudder IS used to pick up a wing, during the falling leaf manoeuvre, this is how you keep the wings level during a stalled condition, with constant rudder input (you need to be quick with your feet), you can keep the wings level and keep aircraft stalled, as it descends, it looks quite spectacular from the ground.

The Extra's spin entry is like any other aerobatic machine, I did some time in the 300L and found it is no different to any other in the entry. All spin entries are similar, however spin recovery, is a very different thing. When teaching inverted spinning in the Pitts I break it right down. Getting the student confident with recovering hands on, then at the very end, when they are proficient with the hands on methods in various attitudes with varying amounts of power and aileron, I show them the Beggs/Mueller method during a full accelerated and flat inverted spin from 7500ft. They are always suprised at how effective this method really is.

Anyway, regarding this "keeping wings level while fully stalled" topic, as stated above, I believe what you are effectively doing, is creating a falling leaf, which you control with rudder, and rudder only. The aircraft slews from left to right when viewed from the ground but in flight it just feels as if it is tipping from left to right (in the tiger anyway).

Interesting stuff.

[bjornhall]

What you say makes sense to me in the main, but I didn't like the idea of the roll damping 'catching' the roll. Unless I'm mistaken, damping is just a resistance to movement (in this case the roll), an inertia if you like. It will not actively restore the wings level, rather make the aircraft less susceptible to the 'fine detail' level of the wings stalling *exactly* at the same time? I'd still suggest they need to stall substantially together.

Yes, I think we more or less agree, when I am saying the wings do not need to stall at the same time I mean not exactly at the same time. A small asymmetry, such as one wing being slightly more stalled than the other, will be damped out by the roll damping. Without roll damping every stall would have a wing drop since there is always some tiny asymmetry present. But I agree with you that if there is any significant asymmetry, such as when stalling out of a slip, the roll damping will not be enough to prevent the roll.

There is a subtle difference between roll damping and roll wise inertia: The latter is resistance to rolling motion starting when a rolling torque is applied, but once a roll has started the roll wise inertia actually keeps the roll going. Roll damping on the other hand is resistance to the roll motion and will tend to stop the roll if it has started.

I'm also interested in the definition of slip and particularly yaw. Does an aircraft in a stable, straight line sideslip have yaw? It definitely has slip, and I know the fuselage is not pointing in the direction of travel, but I'm inclined to suggest it doesn't have yaw, and if it does, it doesn't have a rate of yaw - all parts of the wing move at the same speed, and in terms of direction and space, it is not moving around the yaw axis. In a sense it's no different to an oblique wing NASA AD-1 - Wikipedia, the free encyclopedia (http://en.wikipedia.org/wiki/NASA_AD-1) flying in a perfectly straight line.

Agreed there as well! When we use rudder to create a slip that will be turned into a bank by the slip roll coupling, we need to yaw... Once the slip is established, there is no yaw. In a dynamic situation where we try to keep the wings level with the rudder there will be altering amounts of slip needed and commanded, thus there will be yaw as well. Overcontrolling and dropping the wing in that situation is likely to carry both yaw and slip into the stall, and that is where the fun starts! :)

Seriously, great fun at 4000 ft when practicing or just goofing around, knowing we are going to stall and that it might be spectacular. Not fun at 400 ft on a slow final for a short field landing in gusty condition, when all we wanted was to keep the wings level in as safe and effective a way as possible. That is why I suggest and will only use rudder-only to keep wings level as a fun exercise at altitude when in that mood, not as a method for slow flight.

Of course, the rest of you do as you see fit! :)

[polyfiber]

I have never heard of a school that taught to use aileron to pick up a wing when stalled. However, just to confuse everyone, flaperons stay effective for roll control even in a fully developed stall. The downside of flaperons is the huge induced drag which results in adverse yaw when at low speeds. Example you roll to the left and the nose slews right if you are not on top of it.

Then to compound the problem when you finaly manage to stall the flaperon you get roll opposite to your stick input! So if you were leading with the rudder to control yaw and you stall the flaperon you have just set youself up for a spin:hmm: Of course the only time you should get into that type of scenario is at altitude practicing slow flight where a spin wouldn't matter, or when you are a few inches off the ground when landing.

[Pilot DAR]

Though I don't disagree with the references to flaperon behavior, I can't think of a certified aircraft which empolys them. I flew the first CH701 many years ago, and experienced what has ben described. It was not good! I ran out of aileron control with flaps extended, and had to supplement with rudder (beyond co-ordinated flight) for standard manuevering. I did not have the opportunity to fly later versions, which I trust were improved!

Getting back to the use of aileron to pick up a wing at the point of a stall... I agree that a deflected aileron does have the affect of changing the local chord line, so as to "increase" the local angle of attack very slightly. However, does not deflected aileron also deepen the camber of the wing locally and thus increase the lift which that portion of the wing will produce, and its resistance to stalling? Would this not offset the affect of the increased angle of the chord line? I do agree that this would vary by aircraft type.

All that said, I continue to read posts, and hear about using rudder in isolation to control roll during a stall, but I do not read about it in any authoritative document. I do read about "normal" use of the control through the stall (which I tak eto contradict the rudder only technique). Why the discrepancy in information? Usually our industry is all about consistancy and traceability (of information, in this case). It seems not so much in this case...

[polyfiber]

Good question DAR, remember we are talking of a wing that is already stalled. It has reached its burble point and the airlow is in a seperated state over the top of the wing , no laminar flow at all. Any increase in the ailerons deflection is only increasing drag and, of course, increasing yaw.

Yaw + stall = spin. You cannot autorotate without yaw. Fat high lift wings with washout, that you find on most GA planes, are tollerant of sloppy handling to a point. Most will even recover from a spin by relaxing the controls if they were originaly trimmed for level flight and it is only in the insipient phase. Try putting a Mooney in a deep stall and use aileron to level the wing without rudder. You will see what I mean.

I think that POH's don't bother to tell you NOT to level your wings in a stall with ailerons for the same reason they dont' tell you NOT to push the stick forward to climb. It is something that you should have caught onto a long time ago.

Helicopters put an end to the developement of fixed wing STOL in GA aircraft, and there were certified AC with flaperons.

[IO540]

If the wings are completely stalled then the rudder is the only way to keep them level, but at the onset of the buffet only the inboard part of a wing should be stalled (on a certified / properly designed plane) and the ailerons should still work.

[englishal]

Isn't there the risk then that excessive aileron use may cause the outside of one wing to then stall by exceeding AoA and the drop to happen (i.e. one wing stalled inner and outer and the other only stalled inner)? Especially with types like the Cessna which don't have the stall strips on the inner leading edges and a lower dihedral wing?

[Mark1234]

To your specific question PilotDAR - when I was taught to fly the first time, in gliders in the UK there were a couple of relevant exercises that were marked off as part of the syllabus, rather than simply passed on by the instructor; they were the changing effects of rudder and aileron near the stall (predominance of secondary effects I mentioned previously, which I've experienced in a K13), and a spin entry off aileron alone, by holding off bank in a shallow turn.

I've tried to find a reference to these, as I'm guessing they must be in some sort of training manual, but can't find anything. http://www.lasham.org.uk/members/manual/Training%20syllabus.pdf does make a minor reference, but that's all.

I wonder if the reason there's not much firm guidance is a combination of factors: 1) behaviour in this regime is probably rather type specific 2) We're a rather litigous society so nobody wants to stick their neck out (normal could mean anything!) 3) appart from a lunatic fringe, aviation in general attempts to stay well away from exploring these corners, and when encountered get out of them fast. A quick unload to make the wing fly again, and you're away. No need to worry. Personally I think that's to the detriment of handling skills, but that's another arguament.

I also suspect that the 'increasing the AOA of the wingtip' explanation for an aileron induced spin is in the category of 'lies to children' - a vast oversimplification of what actually happens, but adequate for the audience. I can't argue with the principle having exprienced it, though I'm sure it's type specific.

On the flipside as someone mentioned pitts's (I couldn't resist), to my embarrassment I've so far failed all (3) attempts to spin one inverted - if you rudder at any time other than right at the break of stall it seems to just yaw with no appreciable roll developing, even when fully stalled. Ok, I'm probably a hamfisted oaf, but did I mention type specific? Go figure!

And finally englishal - I'm under the impression that things like stall strips tend to be bolted on as an afterthought to 'improve' stall behaviour of aircraft which don't play nice.. I'm more inclined to worry about the behaviour of aircraft that have them, than aircraft that don't!

[24Carrot]

Just one point about exceeding the AoA and getting a wing drop.

Near the stall, lift hardly depends at all on angle of attack, so the ailerons have very little impact on wingtip lift. In particular the stalled wingtip continues to produce very significant lift, but has become unstable in the sense that any further increase in angle of attack reduces lift, which usually increases angle of attack because of increasing roll.

In the turbulent conditions of a stall, almost anything could get this started.

As an aside, this instability approach explains why stalling the whole wing while landing is so much gentler than stalling at height - the wheels stop any rapid descent and so the just-stalled wing still produces lots of lift.

[n5296s]

I've been following this thread with a lot of interest, but not chiming in because I'm not sure what I have to contribute, But what the heck...

My plane (TR182) will fly in the stalled regime using ailerons for gentile roll. I'm sure that if you oput in full aileron it would probably snap - I haven't tried it. But *tiny* amounts of aileron do what it says on the tin.

Just the other day I flew a falling leaf (or what I call falling leaf)... stall, hold the yoke in your lap, and fly using rudder to keep the wings level. No sweat. sometimes you put in a bootload of rudder but overall it flies very nicely. The key thing is to stay ahead of the game and relax rudder as soon as it starts to respond.

I also did the same thing in the Pitts recently. Hold the stall, stick full back, and keep wings level (more or less) with rudder. No problem.

I've only tried this in one plane where it didn't work - that was a Citabria that was clearly badly out of trim. After I got into two incipient spins, my instructor (who seriously knows what he is doing) said "let me show you" - and promptly did the same thing. We agreed that something needed adjusting, and did something else instead.

Bottom line - ailerons SHOULD work but rudder definitely DOES work.

John

[bookworm]

Near the stall, lift hardly depends at all on angle of attack, so the ailerons have very little impact on wingtip lift.

That doesn't follow. The ailerons don't work by changing the AoA of the wing. The aileron is a trailing edge flap that is deflected. If you look at the lift plots for such devices, you'll see that they are effective in increasing lift coefficient all the way to stall, but that the AoA (measured by reference to the original chord line) for maximum lift is marginally reduced.

There is a subtle difference between roll damping and roll wise inertia: The latter is resistance to rolling motion starting when a rolling torque is applied, but once a roll has started the roll wise inertia actually keeps the roll going. Roll damping on the other hand is resistance to the roll motion and will tend to stop the roll if it has started.

But what you don't mention, is that roll-damping depends on the positive slope of lift vs AoA. In the stalled regime, where lift decreases with AoA, this mode becomes an instability. And it's this that makes spin entry a significant risk if high roll rates develop at or beyond stall, probably even more significantly than yaw rates, although the two are of course linked.

[24Carrot]

ailerons don't work by changing the AoA of the wing. The aileron is a trailing edge flap that is deflected. If you look at the lift plots for such devices, you'll see that they are effective in increasing lift coefficient all the way to stall, but that the AoA (measured by reference to the original chord line) for maximum lift is marginally reduced.Not sure I follow this.

Angle of attack is defined as the angle between the relative wind and a line from leading edge to trailing edge. What else could it be? Ailerons and flaps move the trailing edge, so their main function is to change the AoA of the wing section. They also increase camber, but that is incidental.

The stall AoA is a maximum lift AoA. You know it is a maximum because both reductions in AoA, and increases to AoA, lower the lift. Which implies that the the graph is pretty flat, ie effectiveness is pretty low. One side is stable, the other isn't.

I should make the usual caveat: even if the inner wings are stalled, the outer wings might not be, etc. I am talking abut stalled wingtips (which modern designs try to avoid). Perhaps you were talking about aileron effectiveness when only the inner section is stalled?

[bookworm]

Angle of attack is defined as the angle between the relative wind and a line from leading edge to trailing edge. What else could it be? Ailerons and flaps move the trailing edge, so their main function is to change the AoA of the wing section. They also increase camber, but that is incidental.

There are two points here -- one is about convention, the other is about the relative magnitude of two effects.

Conventionally, when the effect on a wing section of flap is measured for various AoAs, the AoA is measured by reference to the original chord line. But I agree that you could look at the section with flap deflected as being a new wing section, and that the chord line has changed to accommodate the flap, changing the "effective AoA". That's just a definitional thing. What's more interesting is what proportion of the change in lift comes from the new shape, and what proportion from the new effective AoA, to the extent that it's possible to partition the effects.

If I look at Abbott and von Doenhoff (http://books.google.co.uk/books?id=DPZYUGNyuboC) figure 100 (page 195), it shows experimentally measured lift coefficients for different AoAs and different flap deflections of a 20% chord sealed plain flap for a NACA 66(215)-216 aerofoil.

The plain section, with no flap, has a lift coefficient of 0.2 at zero AoA, 0.92 at 8 degrees, and maximum of 1.42 at 16 degrees.

Deflecting a flap 15 deg gives a lift coefficient of 0.85 at zero AoA, 1.4 at 8 degrees, and maximum of 1.75 at 15 degrees, where those AoAs are measured in the conventional way with respect to the original chord line of the section.

Looking at the effective AoA, dropping a 20% flap by 15 deg lowers the trailing edge by an amount equivalent to about 3 degree tilt of the chord line. So you could argue that those numbers are 0.85 at 3 deg "effective AoA", 1.4 at 11 degrees, and maximum of 1.75 at 18 degrees, where those "effective AoAs" are measured with respect to the new chord line of the section with the flap deflected.

You can compare those numbers with the effect of changing the AoA of the entire original unflapped section by 3 degrees. At 3 degrees the lift coefficient is 0.5. So one could roughly apportion the effect on the original unflapped section of extending 15 degrees flap at zero AoA as being 0.3 from tilting the original chord line, and 0.35 from changing the shape (camber) of the section.

That's actually more to do with the "tilt" than I had suspected, and more to do with the "camber" than you had suspected.

[24Carrot]

To be fair there are various Angle of Attack definitions, though I think all are as above plus or minus some angle of incidence or similar.

IMHO the definition I give is the most helpful when understanding the lift of a wing section.

[24Carrot]

bookworm, I posted #54 before reading #53.
Your analysis looks good to me and I agree with your final line.

[whowhenwhy]

From an instructional (TMG) perspective, ease the stick centrally forward to adopt the recovery attitude (slightly lower than approach attitude). Once you have safe flying speed (5kts over stall) then you can worry about rolling the wings level, prior to resetting straight and level flight using PAT!

[Pilot DAR]

Please forgive my not knowing who PAT is, copilot?

then you can worry about rolling the wings level, prior to resetting straight and level flight using PAT!

The exercise is though to demonstrate that the bank angle can be controlled through the stall (the aforementioned design requirement that we are testing for). For this reason, it's not an option to let it get away, then get it back later.

In a more practical sense, pilots would like to feel assured that if they foolishly allow the aircraft to stall (short final perhaps) they can have some faith that when they recover it, it's still pointed more or less where they started, with the wings more or less level, presuming they put the proper corrective effort into the recovery.

So why are some pilots trained that the proper recovery effort does not include the use of ailerons, when the design requirement says it should?

[Pilot DAR]

I was just up stalling my 1975 C-150M. It is equipped with a Horton STOL kit, and has the taller rudder of the later 150's (more authority than earlier 150's). During the approach to stall it was not possible to maintain roll control with rudder alone. I reached the rudder stop on each occasion, while the gentle rolloff continued - damped, but not overcome. When allowed to break in the stall under these circumstances (roll within 15 degrees of level, hardly controlled, but lots of yaw), the predictable spin resulted, but had not been deliberately entered.

[bjornhall]

Doing some substantial googling, one finds a number of references to the rudder-only method on "my personal thoughts of flight instruction/stall training" type sites...

Whereas all authoritative sources one finds on flight training and instruction standards (from US, Canadian and Australian civil aviation authorities for example) say aileron should be used for roll control up to the stall.

Seems pretty clear what "normal use of the controls" means in the modern world. :ok:

[whowhenwhy]

Roll control up to the stall - yup agree with that bjornhall!

As far as using the ailerons during the stall and immediately after to affect the recovery is concerned, I was always taught that you may end up spinning the aircraft. The aircraft may drop a wing during the stall, but if you immediately try to correct it with aileron before attaining safe flying speed, all you'll do is enter a deeper stall and potentially spin the aircraft.

PAT = Power Attitude Trim. The theory is that there must have been some reason that you entered or approached the stall, which would probably be an incorrect P A or T setting. Once you've recovered from the stall, reset PAT and continue onwards to destination, seeing and avoiding as you go!

[Pilot DAR]

PAT, got it, thanks! More acronyms... They seem to be somewhat different on each side of the Atlantic, as there are many in PPRuNe which are just a mystery to me.

Having taken up the rudder only issue with my well respected local flying instructor today, she informas me that she would like her students to lead with the rudder, simply so as to not forget to use it. She does not teach or endorse rudder only, or deliberate uncoordinated flight at any point near the stall though.

To me, the mystery of why instruction is given, which apparently conflicts with the certification requirements of the aircraft, continues....

[bjornhall]

I agree with the part that if a wing drops uncontrollably, trying to raise it is not the ideal thing to do! :ok: Recover from the stall first, then level the wings.

But if one does try to do it the other way around, at least merely trying recover from moderate bank while in a stall (rather than trying to arrest an uncontrollable roll), in a modern certified aircraft, one would generally find ailerons to be effective. A spin would not normally result. That does not mean one should do it; it just means that if one does anyway, for example due to not realizing one is in a stall, in a modern aircraft one should not end up killing oneself.

If one is flying something old or uncertified on the other hand and tries that... :ouch:

[24Carrot]

...one would generally find ailerons to be effective...To some extent, as has been said above by many, but ailerons AND rudder, because however good ailerons are or aren't at controlling bank angle near the stall, they are extremely good at adding wing tip drag.

And if only rudder turns out to work, then you have that covered too...

[polyfiber]

Hello DAR,

Glad to see you are up trying out your plane in different flight modes.:ok: I used to own a 150 and they are probably the most underated plane out there. They really are a great machine in my opinion. Try doing a falling leaf.

What you do is get a lot of altitude... put the plane in a nice gentle stall. Keep the yoke back, all the way, and dial in a bit throttle. About 1800 rpm. Then as it wants to drop a wing use rudder to keep it up but... over rudder to make it bank even more the opposite way. In other words it will drop the left wing give it full right rudder and allow it to bank untill you are at least as far to the right as you were to the left. Repeat until you are ready to recover.

It is a great co-ordination exercise all though it would not be considered aerobatics it requires a lot more skill than looping or rolling!

[polyfiber]

Mark 1234,

If you have never done an inverted spin in a Pitts you must do perfect hammerheads. Hint..a Pitts will only stay in a spin inverted in one direction.

[polyfiber]

IO 540,

Your keening for the characteristics of the certified AC is the opposite of the EAA homebuilding movement. If you enjoy dull, lethargic, glacial control response stick with over twisted, stall stripped, parachute equiped, nose dragging crap they are churning out now.

You probably would not venture forth without your GPS batteries being fully charged either. It is no wonder Canada had so many Aces in WW1.

[ridan]

First, there isn't a "perfect" hammerhead... ask any FAI/IAC aerobatic judge. Second, from a botched hammerhead, the Pitts will most likely end up in a left pedal inverted spin... however, that depends on what the pilot is doing with his feet.

Hint... a Pitts will sustain an inverted spin in either direction.

[CanAmdelta1]

See POH
Do HASELL
Power off stall-throttle idle
Keep wings level to prevent wing drop and possible autorotatation. Use AI, wing tips and their relation to horizon. Keep coordinated(ball), pitch up. Use of Ailerons may cause wing drop. Use opposite rudder to catch wing drop. When stall occurs -recover-relieve backpressure on yoke/stick, full power on carb heat off.
As we all know relative AOA is the cause. However several control inputs are warranted individually or sequentially depending on type of stall ie: assending banked stall etc.

[Pilot DAR]

How will we Keep coordinated(ball), if we are Use opposite rudder to catch wing drop?

Use of Ailerons may cause wing drop. This is the heart of my original question; where does an authoritative document say this? It is a design requirement for certified aircraft that "normal" [co-ordinated] use of the controls are applied for control of roll up to the point of the stall. It is not a design requirement that rudder be used, or be able to be used, to the exclusion of the ailerons, to controll roll up to the stall.

During a recent flight with a flying instructor in my C-150, I demonstrated that rudder (and I have the taller rudder, later model fin) is not adequate to arrest or recover a roll off of more than 10 degrees during the approach to a stall. She seemed suprized, and I felt her checking to see that I did have full rudder applied - I did, and it was still rolling off uncontrollably, with my holding the ailerons rigidly neutral.

[CanAmdelta1]

So this 150 will not, with coordinated controls pitch up with power off and stall with wings level with the world at high AOA then nose over gently with wings still level but with a lower AOA?
Apologies but just trying to understand so I may give feedback.

[Pilot DAR]

This 150 will, with co-ordinated use of controls, stall wings level very nicely. This will, of course involve the use of ailerons right up to the stall to keep the wings level.

Even without a lot of roll & yaw control input, it will generally stall and pitch down with the wings fairly level. If the stall is done with some power, and/or there is turbulent air, dropping a wing a little is not unusual. I have found this to be the case with many aircraft I have stalled. Some drop a wing a little (a few a lot!) during a stall, and some control input is needed during the approach to stall to keep wings level, and ball centered.

There is an understood "normal" use of controls, in harmony, and co-ordinated. I do not agree that there comes a point during the approach to stall when controls should no longer used "normally", and skidding becomes appropriate.

[CanAmdelta1]

My experience basically same as yours except in a 152. Aileron full deflections mostly seem ineffective close to the stall point although I have seen wing slowly start drop with ailerons.
Anyway, good thread and responses.

[CanAmdelta1]

My experience basically same as yours except mine was in a 152. Aileron full deflections mostly seem ineffective close to the stall point although I have seen wing slowly start a drop with ailerons.
Anyway, good thread and responses.