Stalling

[TurboJ]

Flight Training News Pg 13 discusses an accident involving a student and his instructor whereby he was teaching stall recovery and unfortunately didn't recover from a spin.

The AAIB have made a safety recommendation that 'oscillatory stalling' is not included in any flight exercises during flight training.

Oscillatory stalling is described as 'holding the aircraft in the stall using maintained back pressure on the control column when leads to a nodding motion or 'oscillating' pitching movement. With appropriate rudder inputs to control any wing drop this could lead to a spin.

My question is this:

Flight exercises on stalling include entries, symptoms and characteristics of being stalled. In a PA28, the nose nod or 'oscillatory pitching movement' is a symptom of the stall.

In order for students to experience how this feels and therefore be able to recover, I also allow students to enter a stall and hold a stall with maintained back pressure before they recover, keeping the aircraft in balance with light inputs to the rudder and alierons kept neutral. Flight Training News also appear to have spoken to a number of instructors where this practise is regarded as common place.

Are the AAIB saying that holding an aircraft in a deep stall for students to experience its effects and subsequent recovery should be stopped as it is not safe practise due to being close to the ingredients of a spin ?

At what stage approaching the stall do you therefore allow a student to recover ? Incipient or actually stalled ?

I would be interested in other instructors thoughts !!

[unfazed]

TurboJ

The recommendation was about holding it in a stall

If you enter a fully developed stall and recover after experiencing the sensations of a fully stalled aircraft then fine:)

The recommendation was to avoid holding the stick back and maintaining the stall (which I know a lot of instructors do as a routine thing).

Probably more likely to inadvertantly spin if practicing the latter:{

[bogbeagle]

What is the purpose of this manoeuvre? Anyone?

[BEagle]

None whatever! If you use rudder for anything other than maintaining balance during a stall, you are inviting a spin. 'Stopping wing drop' or, even worse, 'picking up a wing with rudder' is an archaic nonsense which should have been stamped on years ago.

Also, never let a student hold the a/c in the stall unless you are doing so to demonstrate light pre-stall buffet management if your a/c type has such a characteristic.

The student is learning to recognise and recover from the stall with minimum height loss. You show him (with him following through) the identification of the fully developed stall - buffet, nose drop, wing drop, high RoD, nodding dog or whatever, then tell him that any one of those is an indication of a fully developed stall and he should recover when he recognises any of those stall identifications.

I don't use 'signs' and 'symptoms' ever since medical stuents commented that this was bolleaux. So now it's stall warnings (keep going and I'm going to stall, idiot!) and stall identifications (I warned you, you didn't listen and now I bloody well HAVE stalled like wot I told you I was going to!).

[bogbeagle]

BEagle

Succinctly put. I was hoping that someone would quickly pounce on the "pick up the wing with rudder" old wives' tale.

Have to confess to some disappointment at the alacrity of your response, though. I expected the "rudder" proponents to jump to its defence. I s'pose that thread is done and dusted now.

[BigEndBob]

The problem seems to be they didn't recover from the spin!
Was it a Slingsby by any chance?

[7gcbc]

BEagle
Succinctly put. I was hoping that someone would quickly pounce on the "pick up the wing with rudder" old wives' tale.
Have to confess to some disappointment at the alacrity of your response, though. I expected the "rudder" proponents to jump to its defence. I s'pose that thread is done and dusted now.


so Aerlion is better to lift the downgoing wing ?

[RVR800]

The point here is teach the students to recover from the stall but NOT to teach him to sustain it - you want to limit height loss

(Full Aileron control will be possible when the recovery is effected)

[BillieBob]

so Aerlion is better to lift the downgoing wing ?Correct (assuming that you mean aileron)- but only when the wings are unstalled.

[7gcbc]

hmm, assuming every stall occurs in a benign and balanced state (i.e little or no yaw or +/- gz), then the aileron would suffice.

what about unbalanced, a turn, any significant yaw, either wing going south, (obviously so) , in that case using aileron will only accelerate the "south" going wing, whether erect or inverted an to be honest, you really have to begin using your feet at that stage. (i.e step on the ball) which is not really "using rudder to pick up the wing" , all you are doing is kicking her around, removing the yaw, so a modicum of stick fwd/bwd as the case may be moves you away from the stall-departure zone

Not sure personally about the deep (mush) stall in a pa-series, but it would certainly give a student confidence, if they wish to be cpl's then surely they want to explore all the facets of an aircraft characteristics ? (from a safe height I may add)

[BEagle]

Anyone 'kicking her around' at low speed should themselves receive a sound kicking!

Standard Stall Recovery:

FULL POWER and Control Column centrally forward until Stall Identification ceases.

Then (and only then) level the wings.

Then recover from the descent.

DO NOT USE RUDDER FOR ANY OTHER PURPOSE THAN TO MAINTAIN BALANCE!

[TurboJ]

Beagle

FULL POWER and Control Column centrally forward until Stall Identification ceases.


I was criticised on a check flight with an FIC for the order in which I explained standard stall recovery.

I was told it should be control column forward to reduce the angle of attack of the wings and then apply full power.

Reason ? The effect of applying full power causes the nose to raise which increases the angle of attack, thereby prolonging the stall !!

Therefore standard stall recovery:

Relax the back pressure to reduce the angle of attack of the wings.
Apply full power.
Maintain aircraft in balance by controlling yaw with rudder.
Once speed increases past Vx, select a climbing attitude.
Check carb heat to off, unless selected off as airspeed was reducing.

To quote a legendary CFI, instructing is all about terminology ! I realise its being pedantic......however that was the critique of a recent check flight

TJ

[7gcbc]

Anyone 'kicking her around' at low speed should themselves receive a sound kicking!
Standard Stall Recovery:
FULL POWER and Control Column centrally forward until Stall Identification ceases.
Then (and only then) level the wings.
Then recover from the descent.
DO NOT USE RUDDER FOR ANY OTHER PURPOSE THAN TO MAINTAIN BALANCE!


some of us don't fly straight and level all the time.

oh, and adding full power as you mention, would in some aircraft (because of the low speed and associated torque) roll you on your back.

what then ?

[RVR800]

Zgcbc...............

Anyway going back to the original issue it seems a good idea to
keep things simple.

We are teaching a student to fly.

We KIS - Keep it simple.

Hence Ex 10A Slow flight
Ex 10B Stalling

This is stall prevention
and stall recovery .... and thats what this thread is all about

Keep it simple and there will be no problems OK :}

'Standard Stall Recovery'

1 Stick centrally forward to unstall the wing
2 Full power to reduce height loss
3 Prevent/reduce wing drop if it occurs with opposite rudder
4 When all signs of the stall have ceased nose to the horizon then climb away if necessary when speed increases

1. Centrally forward to reduce chance of wing drop possibly leading to a spin but PRIMARILY TO REDUCE THE ANGLE OF ATTACK which is why you are stalling in the first place

2 Full power to reduce height loss. - student not convinced? show them a stall and don't use power to recover - amazing! the aircraft still recovers just loses more hight

3 Use the secondary effect of rudder to prevent the wing dropping further as trying to use aileron will only increase the angle o attack further and lead to further wing drop etc

4 Nose to horizon when stall has ceased

[Charlie Foxtrot India]

Often hear instructors talk about "teaching stalling" when we should be teaching NOT to stall.

Have also heard an instructor brief a stude that the first thing you should do if you get a wing drop is apply "full opposite rudder" :uhoh: Turns out one of the schools round here really does teach thier instructor trainees this! They also send their studes to "practice stalling" solo :uhoh:

The main thing is to reduce angle of attack, I tell them not to apply power until you have at least 60 knots (PA38, PA28) hopefully by this ex they should be able to recognise the "feel" of the airspeed without having to look at the ASI. Applying power too early will induce yaw and could lead to a wing drop. Secondary importance of power is shown by the fact that gliders can recover from stalls, too!

[7gcbc]

apologies for intrusion.......:uhoh:

[BEagle]

TurboJ, I respectfully contend that the FIC instructor was an utter ar$e! If you do not control the a/c attitude and balance when applying full power, then stall recovery may well be delayed. Delaying application of full power will certainly increase the height loss during recovery.

Charlie Foxtrot India - maybe it's some of your ex-students to whom we've had to re-teach stall recovery. Why wait until 60KIAS? Teach them to maintain balance and to control the attitude correctly when applying full power!

And that old wives' tale of full power at low speed causing a/c to roll onto their backs is a myth with certificated aircraft.

[bogbeagle]

It's clear from the thread that opinion varies quite widely. Since we can't all be correct in our methodology, it must be the case that lots of students are being badly taught.

I've heard it said that, in general in the UK, stall-spin awareness is an area in which FIs do let down their students. I've certainly met chaps (not FIs) who believe that they can recover from a stall solely with the application of power.........and others who engage in "now-legendary" frantic rudder-paddling in an attempt to prevent any wing drop. In my experience, very few PPLs are comfortable with flight at the lower speeds......so landings are bound to be a bit of a trial, aren't they?

I know that at my school, the 2 hours stall-spin awareness is often severely curtailed and the exercises are skimped in order to rush into the circuit. Appropriate adjustments are then made to the student' records in order to fulfil the criteria for licence issue.

I'd be surprised if my experiences are unusual.

The wider issue is, I think, one of standards. There does prevail, in some schools, a propensity to teach down to a price, rather than up to a standard. This is facilitated by the system of examination for the PPL' syllabus. Far better, in my opinion, to adopt a system more akin to CAAFU.....where the examiner has no commercial interest in the student's outcome.

If an independent examiner regularly found that X's students were complete duffers at low-speed work, there would be an opportunity to address X's deficiencies, I suppose.

Anyone else seen fragrant abuses by "school" examiners? Or perhaps I shouldn't ask.

[bogbeagle]

did I really say "fragrant abuses"?

[greeners]

Bogbeagle

Absolutely bang on (fragrance aside).

[FlyingForFun]

I know that at my school, the 2 hours stall-spin awareness is often severely curtailedWhich 2 hours is that?

To the best of my knowledge, there is no requirement for any minimum amount of stall-spin awareness, and there hasn't been since the introduction of JAR. There are a number of different stalling scenarios to be covered, the aim being for the student to understand the symptoms of the approaching stall and the fully developed stall, and to be able to recover with minimum height loss. Once a student can perform these excercises satisfactorilly (and by that I mean that the student has demonstrated sufficient knowledge of the stall and the recovery of the stall to be able to carry out the exercises), move on to circuits. For some students, this will take less than an hour. For others it will take several hours.

FFF
---------------

[Dan Winterland]

This thread re-opens the argument (from a previous thread) for the need for some sort of instructor standardization body.

[BigEndBob]

Question is why do we teach stall recognition and recovery.
When is an aircraft going to stall.
Probably not at 4000 feet on a bright sunny day.

When an aircraft stalls and the wing drops eg C152/PA38 the first thing a pilot does is apply opposite aileron, worsening the situation. And is unlikely to be power off.
It is an instinctive reaction to aircraft roll.
We all know it probably takes an hour of stall practise to teach the student not to use aileron, which quickly gets forgotten.

And i would imagine that any instructor on a windy day climb out experiencing severe wing drop would probably also use aileron to recover combined with rudder.

[7gcbc]

exactly right, you should stall the aircraft in as many possible legal flight configurations as you can manage, climbing full power, climbing turning full power , descending flaps, tighten up turns and so forth.

This malarky about straight ahead summers day stalling is leading students up the primrose path.

by the way Beagle, I have rolled a Cessna 152 years ago in a high AOA, slow speed , with flap and fullpower , and I can tell rudder had absolutely no effect round she went and we were along for the ride.......

and I pickup the downgoing wing all the time when I do aeros, and I do it with tap tap rudder, and whatever stick is rwq'd

[BEagle]

The flowers you will probably need will not be primroses......

[john_tullamarine]

Another consideration which I don't think anyone has highlighted relates to the certification requirements .. ie what is demonstrated and investigated during the OEM development and regulatory certification process.

This has varied over the years. One should have an idea of what the particular aircraft was subject to ... if one goes outside this .. then one might get an unpleasant surprise at some stage.

For instance, one popular light twin was certificated on the basis of only approaching to the indications of stall .. a very experienced test pilot instructor related the tale of one of his students who persevered with holding an example of the Type/Model into the stall ... and promptly ended up in an inverted spin.

What the OEM writes up in the handling notes, POH, etc., is worth giving due weight .....

[bogbeagle]

FFF

Quite right. Another misapprehension bites the dust, courtesy of JAR FCL 1.125, appendix 1.

So, no minimum requirement for stall-spin awareness training......or instrument awareness.

[bogbeagle]

"misapprehension". My dear Mrs Malaprop, surely you mean misconception

[Rosanna]

TurboJ, I respectfully contend that the FIC instructor was an utter ar$e! If you do not control the a/c attitude and balance when applying full power, then stall recovery may well be delayed. Delaying application of full power will certainly increase the height loss during recovery.

I agree with you that a recovery with power reduces the altitude loss but if we teach students to apply full power when the stick is still forward the situation may become dangerous. A friend of mine died with a C152 because they stalled and applying full power the aircraft spinned.
For this reason I want that my students learn to:
1) reduce AOA and only after that
2) apply full power
Usually in the first recovery the student will lose a lot of altitude. But after 3 or 4 recoveries he/she take confidence with the sequence, full power is really close to nose down, and the altitude loss will decrease.

Ciao!!!

Rosanna

[Ultranomad]

I second Rosanna's post. It's especially true of less stable aircraft like PA38, any aerobatic planes, etc. - applying full power early in the stall/spin tends to cause a flat spin.

[Dan Winterland]

I find this thread very illuminating. People are talking about picking up wings with rudder and 112hp engines causing the aircraft to rotate around it's longitudinal axis with the controls having no effect and/or causing 'flat spins'. This all makes me believe that they have been taught incorrectly and are teaching incorrectly.

I'm talking about the CAA /JAR syllabus here and not the FAA or CASA one, which I have little experience of but I believe they are similar. I always thought that stalling exercise was a prevention exercise and to get the best out of it, recognition has to be taught first. Then recovery with minimum height loss in various configurations and attitudes. The key to this is with 'minimum height loss' and you can only achieve this with the application of power. This is how I was taught to teach the exercise and how I always did it myself.

1: Recognition - take some time on this, if the student can't recognize the warnings of the approaching stall or the stall itself there is no point in continuing.

2: Recovery - this can be achieved with reducing the angle of attack. You should elicit from the student the height loss, then point out the loss with use of power. (The last aircraft I was teaching on, the PA 28 typically lost 300' in a recovery without power, 100' with.)

This should take a minimum of a whole hour long lesson if it's going to be done properly with the average student. Then:

3: Recognition and recovery in other configurations/ attitudes (with flap, power, gear, air brakes, asymmetric, any attitude - even upside down if you like!) The key to this is the recovery with min height loss with the emphasis of saving you skin on the approach to landing stall. To achieve this effectively, you have to build up a scenario with a high workload and distractions. this should take more than one lesson.

The stall recovery is simplicity itself in it's execution (although you wouldn't believe it reading this thread!). You move the control column centrally forward until the buffet stops, simultaneously applying full power. You use the rudder TO PREVENT FURTHER YAW - and this only! When the wings are unstalled (i.e there is no buffet - and this is another reason you have to have to have the recognition squared away), you select a level attitude with aileron and elevator.
Some points on what has been said here.

Use of rudder: tramping the rudder around other than to prevent yaw is asking for trouble. The primary recognition points of an incipient spin are buffet with undemand yaw. If you demand some yaw intentionally by using more rudder than is required to prevent any yaw from the action of the stall or applying power, you are inviting the aircraft to spin.

Use of aileron: By increasing the angle of attack by lowering an aileron, you are inducing the wing to stall deeper. In my experience the only aircraft where aileron use with buffet was appropriate was a swept wing jet where the aerodynamics are very different.

Use of power: To reduce the height loss, you need power. The last aircraft I instructed on professionally stalled at about 80 knots and has a 1200hp engine. There was no problem controlling it at the point of stall with full power. The only aircraft to my knowledge which had a problem with this was the Bolton Paul Baliol with a 1600hp merlin engine. It was taken out of RAF service partly for this reason. If an aircraft cannot be controlled in this fashion it would not be certified. (This may not apply to some multi-engine types asymmetric if they are at or below their Vmca).

The only slightly dodgy stall characteristic I have ever experienced was the Tucano which rolls to about 120 degrees angle of bank at the stall in a final approach configuration stall in a left turn. Still, by following the recognized recovery technique, it is still possible to recover in about 400' safely. To get to this stage though, you have to ignore the warnings of the high nose attitude, the less effective controls, the low and decreasing airspeed, the audio warner, the stick shaker, the angle of attack gauge, the approach angle of attack indicator - and the buffet! This re-enforces the emphasis on recognition.


Roll on instructor standardization!

[Norwester]

I can't add anything to this post, except to offer thanks to Dan.

Dan's post has put my mind at rest that my training in recognising the 'incipient stall' in various configs and the recovery procedures wasn't at all incorrect afterall.

I was a bit concerned to read posts that suggested the rudder be applied for anything other than to prevent further yaw on applying power.

[TurboJ]

Dan

Thanks for your post. I am very pleased to be 'singing from the same hymn sheet.'

However, I come back to my original point.

Recognition - take some time on this, if the student can't recognize the warnings of the approaching stall or the stall itself there is no point in continuing.

In a PA28,the stall itself includes an oscillatory pitching effect which the AAIB says is not included in ab initio flight training and should not be practised by UK flying instructors. However, students are required to be able to recover from a fully developed stall which includes this pitching effect.

Would it be right to say that as soon as this 'nodding effect' is reached, the student recovers or the fully developed stall should not be developed to include this oscillatory effect.

Regards......TJ

[pilgrim flyer]

Coming from a gliding instructing background, I can only concur the stall/spin recognition/avoidance/recovery is at least inconstantly, if not badly, taught.

BGA instructors are rigorously coached in stall spin recovery in all kinds of configurations and loadings at heights down to below 1000ft (some demo only).

There is a particularly nice one which involves stalling/spin entry in under and over ruddered turns and works really nicely in a C152. All my PPL students get to see it and have a go.

From my perspective the ‘spin avoidance only’ teaching is a bit of a cop out –possibly engendered by a lack of suitable available aircraft.

PF

[Dan Winterland]

From my experience, the oscillatory pitching effect of the PA28 at the stall is a result of the control column being held and maintained fully back and is a product of the high level of pitch stability enjoyed by that aircraft. If you get to that stage with a student, he/she is flying the aircraft to the limit of its angle of attack capabilities and is in a full deep stall. Remember that the aim of stall training is to recognise the stall at it's onset and recover with the minimum height loss. If you ever take the student to this stage, it should be once and for demonstration purposes only. The aim of this exercise is to recognise the warnings of an approaching stall and avoid them in the future. there should few reasons for the student to take a PA28 to the 'nodding' stage.

I'm glad that someone has bought up the subject of glider stall training. I first trained as a glider instructor and IMHO, glider stall training is superior to powered. Glider pilots are more likely to fly a wider range of types than power pilots and at speeds much closer to the stall. My experience comes from the Bocian (stall below 500' and it's goodbye) through the tailess Fauvel 28 (hoik the stick back and you can flick loop) to the Dart 17 with no washout (stall and you're guarenteed an incipient spin). Some gliders have truly horrible stall characteristics, but most are benign.

[Ultranomad]

People are talking about ... 112hp engines causing the aircraft to rotate around it's longitudinal axis with the controls having no effect and/or causing 'flat spins'.
I have to admit that what I have for Tomahawk is pure hearsay. On the other hand, a 360 hp engine on a Yak-52 (almost twice as heavy as PA38) is known to affect the stalling/spinning behaviour, and the flight manual explicitly prescribes to pull the throttle to idle while recovering from a spin / incipient spin.

[Dan Winterland]

The Yak has a large heavy prop which will acts as a gryroscope. You don't want gyroscopice forces affecting the recovery. I think it has more to do with this rather than the airframe being spun around by the prop. In the Tucano, the incipient spin recovery was centralize the control column and close the throttle - for this reason. In the less powerful Chipmunk and Bulldog, it was just centralise the contol column.

[Ultranomad]

Dan, I totally agree with this one, gyroscopic forces probably have more to do with it. They would also make a bigger contribution to the asymmetry of the situation (left vs. right spin).

[Mintflavour]

While we are on the subject of stall recovery. Just the other day during an
IR(ME) 170A, I carried out the standard stall recovery, ie Stick neutral/forward, Power Wings level etc. I was then corrected by the FI, to recover the Twin engine aircraft from the stall by basically powering out of the stall, no lowering of the nose to reduce AoA. As an FI myself this strongly goes against all of my principles and what I teach my PPL's. Thinking about this further after my 170A (which was signed off incidently), the implications of loss of power in one engine during a stall recovery carried out by power alone could be quite... well dangerous. Any views on ME stall recovery would be appriciated.

thanks
mint

[unfazed]

When a stall catches a student unawares we have hopefully instilled in the student an automatic reaction .....stick forwards and apply full power (simultaneously)

It is difficult to instill an instinctive reaction which has got many variables depending on circumstances hence why we have to boil it down to "pitch and power":) .

[hugh flung_dung]

Mintflavour,
During an MEPL test I expect people to follow the standard patter and to move the stick "sufficiently far forward to unstall the wing" slightly before smoothly adding power. Some people seem to think they need to enter a 30 degree dive and some slam the throttles open - either of these actions will lead to a reminder of the requirement for "minimum height loss" and a question about why throttles need to be handled smoothly (especially near the stall) before (usually) being given a second chance.
Is it possible that you were guilty of stuffing the nose down too far and causing excessive height loss?

HFD

[Mintflavour]

HFD
Yes i did over cook the forward stick, but I knew that straight away, it was the demonstartion afterwards that I was more suprised about.
Mint

[Dan Winterland]

Again this comes down to the phrase 'control column centrally forward until the buffet stops' or whatever words you have been taught to use (these are the CFS words).

In a deep stall, the control column may have to go quite a way forward until you reach the unstalled state - i.e. no buffet. However, if for example you are recovering from a stall in the approach configuration, you may decide that an early recovery is best and you recover at the first recognisable warning. This may be a high nose attitude or the aircraft's stall warning system, or any of the other warnings you know about. Whatever it is, it is likely that it won't be any buffet - so if there is no buffet to remove, you don't have to move the control column very far forward - if at all.

This is why it is so important to get the recognition properly learnt before continuing with the recovery. And as the key to the exercise is life preservation with the key phrase 'with minimum height loss' being the most elemental part of the lesson objective. It should be stressed that an automatic reaction of burying the stick in the instrument panel is not necessarily the best course of action if you stall on the approach at 100'.

[mad_jock]

I was lucky enough on a canceled days flying to have a brief from a visiting CAA exam callsign. Which as you might expect was listened to by students and instructors alike.

The MEP stall recover using the power, only dropping the nose to straight and level attitude was explained as the following.

The recovery is started on the activation of the stall warning system which indicates you are approaching the stall and not actually in the stall. So as such all you are doing is speeding up in a flyable condition. And as such dropping the nose below S&L is an over reaction. The lecture was over 4 years ago now but he did then go on to cover the case of engine failure while performing the manover. If the engine fails before minimum control airbourne is reached you apply full rudder and retard the good engine just enough to remain in control and then advance the power to max as you speed up past any limiting speeds.

In a clean stall to the onset of buffet he was an ex-RAF chap so briefed the RAF standard minimal unload recovery which Dan is doing a fair job explaining.

As Dan said earlier how on earth can Joe Bloggs be expected to know what they are doing when all the major subjects ie PFL's, stalling, standard checks etc are all debated on this forum with very varied opinions on the methods. Joe is going to go from one check ride where he is told to stuff the nose down to one where he will get re-trained if he drops below the horizon.
If the CAA payed someone in the know to write briefing sheets on the topics brought up on this forum and endorsed them as the "method to use" and sent them to all FI's and CRI's and publish them at the back of lasor's for the rest it would be a relatively cheap way of getting some sort of standards in the UK.

[unfazed]

If the CAA payed someone in the know to write briefing sheets on the topics brought up on this forum and endorsed them as the "method to use" and sent them to all FI's and CRI's and publish them at the back of lasor's for the rest it would be a relatively cheap way of getting some sort of standards in the UK.

And they would be out of date the very next day

Diversity is not a bad thing and there are many ways to skin a cat !:)

[mad_jock]

They wouldn't, the RAF have been using the same basic instruction manual for years the one Dan and BEagle got issued proberly only have changes included for the purposes of new aircraft types compared to the one issued today the basic principles of how to fly haven't changed for 50 years.

This diversity line about so many ways to skin a cat is just an excuse so instructors can carry on re-inventing the wheel and plugging there own ideas about how it is meant to be done. The end result is that the whole sylabus has become a mish mash of methods with no real standard. Which people haven't a clue whats expected of them or which one of many perversions along a general theme they are meant to produce.

The instructors think they have found the new in thing but the old method has incorporated years of cock ups and rules of thumb that the boy that killed himself learning that wasn't the way to do it has been forgotten. I suspose its the old stable extravert thing and the personalitys involved which make us all think we know better than the old fart who smells of wee who learn't to fly in a tiger moth after 300 hours of instructing.

The differences between FIC's is becoming more and more marked and now there are no checks now before becoming unrestricted there is no real check on any FI's and their methods. Most get an airline job before the renewal and after that if they decided they want to instruct for a hobby they have had the crap kicked out of them in the sim 8-10 times with defined methods of dealing with stalls etc. And knowing the importance of SOP's and standard methods they forget the invented ones they used as an FI and use the "RAF" methods which work for all types.

I have a feeling that most on this forum if flying together would try and retrain each other if they had a blind flight test with each other.

MJ

[Dan Winterland]

I have a WW2 RAF flying manual for the Miles Magister. The syllabus is very similar to the current RAF and PPL ones. The lesson numbers course construction are almost identical.

Although aircraft have different characteristics, the laws of aerodynamics don't change and the best way to recover from a stall with minimum height loss has not changed since then.

And until we're all flying hover cars, I doubt it will change much in the future either!

[BigEndBob]

Stall recoveries are simple....what method would you use if the aircraft was being held off feet above the runway, which then resulted in a balloon.
We all teach that recovery.

The only time pilots stall aircraft;
1/ Overcooked climbing turn, pilot showing off.
2/ Tight turn to final, low level, crap weather.
3/ Overpitching at roundout with excess speed, power off.

Too many bang on about being in balance on final turn, had this when being checked out by an instructor in the States, i later showed him the balance indicator was not set level on the panel. Keeping in perfect balance may have been true in the Sopwith camel,

[BigEndBob]

And 4/ trying to turn back efato.

[HappyJack260]

Stalling is caused by stick position (via pitching aerofoil up too high relative to airflow). You can demonstrate this by bringing the stick back abruptly, or slowly, at higher speeds, or at low speeds, upright or vertical, level or banked. In all cases the stall will occur at the same stick position (assuming W&B remains constant). Once you know where that stalling point is, it's a simple matter to ensure that (a) you keep the stick forward of it, whilst in the air and (b) if you bring the stick aft of it and cause a stall, you move the stick forward through it to get out of the stall. In the case of inverted flight, for forward read aft, and vice-versa.

But once you're out of the stall, you may be going too slowly to maintain height, so you need power to stay airborne.

Rudder helps keep you balanced and prevents the stall turning into a spin. An interesting exercise is to put the aircraft into a fully stalled position, power off, and then use alternate rudder to keep the ball centred and the aircraft upright - sometimes referred to as a "falling leaf", or a "rudder walk". You'll be losing height the whole time, and you'll be stalled the whole time, but you won't be in a spin.

This sort of practice helped me once when I had an EFATO about 100' off the runway, in a Marchetti SF260 with nowhere to go ahead, and had to crank around 60 degrees to get down on the airfield in one piece, albeitwith a firm arrival, gear up, followed by hospitalisation for both me and the aircraft. Someone killed himself a couple of weeks ago in an EFATO at the same airfield in a Lancair 360.

Avoiding a stall is a good idea; recovering from it will always require stick movement, but in an engine-out situation, or in a glider, or in the Spitfire doing a go-around at Goodwood a few years ago, adding full power is not the first thing to do, and may not be an option.

[Dan Winterland]

Interesting! So a stall will always occur at the same stick position if the weight and balance is the same. So what about loading then? The speed at which a stall will occur is more relevant - and this speed will change at the square root of the load factor. At 1g, if the stalling speed of an aircraft is 60 knots, at 2g, it will be 60 x 1.4 = 84 knots, at 4g it will be 60 x 2 = 120 knots. At 0g, the aircraft will not stall. I suggest that in each of these cases the stick position will be very different.

As for 'walking the rudder' in a stall, enough has been mentioned here for me to not go into why this is not sensible.

I hope you're not teaching your students this nonsense - assuming you're an instructor. Which I hope you're not!

[HappyJack260]

Interesting! So a stall will always occur at the same stick position if the weight and balance is the same. So what about loading then? The speed at which a stall will occur is more relevant - and this speed will change at the square root of the load factor. At 1g, if the stalling speed of an aircraft is 60 knots, at 2g, it will be 60 x 1.4 = 84 knots, at 4g it will be 60 x 2 = 120 knots. At 0g, the aircraft will not stall. I suggest that in each of these cases the stick position will be very different.
As for 'walking the rudder' in a stall, enough has been mentioned here for me to not go into why this is not sensible.
I hope you're not teaching your students this nonsense - assuming you're an instructor. Which I hope you're not!

Neither loading nor speed will change the stick position required to get a stall. In recovering from a stall, speed of recovery is a good thing. You can move the stick quicker than you can change your speed.

And if you put the stick into a position where you are not stalled, chnaging speed or g loading won't make you stall. If you move the stick and thus stall the aircraft, changing the speed or the loading won't unstall it, either.

I've also explained that "walking the rudder" can allow you to keep the aircraft level in a deep stall. I didn't suggest that keeping the aircraft in a deep stall was a good idea.

No, I'm not an instructor. I have found that many instructors are ignorant on this point though. I myself learned this relatively recently from a couple of highly experienced instructors, both of whom teach aerobatics and therefore get to explore aircraft behaviour across a wider range of attitudes than many pilots usually experience. I didn't believe it until I climbed into an aerobatic aircraft and checked this explanation out for myself across a wide range of speeds, loadings, pitch and bank angles. I found it holds good.

You might like to get off your keyboard and into the cockpit if you want to check this out, too. Or have your prejudices overcome your willingness to learn from experience?

[1972]

Sorry to intrude, I'm no FI or Examiner (pre-GFPT) but have to say that as a student who is having some difficulty with mastering stalls, this thread is great stuff.

Despite being very happy with my FI who is very encouraging and doing everything they can to help me master the stall, I've probably got a problem with the exercise. I think I'm okay with the theory side of things but putting it into practice appears to be a stumbling block! And most of it is probably not having enough bottle!

This was probably due to the unexpected experience (and sensation) of bad wing-drop. I 'instinctively' used aileron in the heat of the moment to correct (despite being briefed to use rudder) and obviously things only got worse till I let go of the controls and let my FI get us out of it. On the outside I probably seemed fairly calm, inside I was s***ting myself!

Have now had 1.5 hours on the stall and still have a few to complete. (FI doesn't want to scare me away)! Is this time-frame for your first stall exercises 'normal' for students?

Sorry for the thread-creep, but if anyone can answer I'd really appreciate a PM assuming you don't want to deviate from the topic by posting here. :ok:

'72.

[FlyingForFun]

1972,

It's unfortunate that you experienced this wing drop. The aim of the stalling exercises is to absolutely drill into you the recognition and correct recovery from a stall, so that you hopefully recognise the stall before it happens, and if by some chance you don't you then automatically use rudder to prevent yaw which in turn will prevent any wing-drop from developing. These must be instinctive reactions if you are to avoid scaring yourself like this again!

The answer to your question is that, if you can not carry out the correct recovery instinctively, you have not finished the exercise. There is no set time that it takes to complete the exericise - in fact, before JAR, there was a requirement for a minimum of 2 hours of stalling, so your 1.5 hours so far are certainly nothing to be ashamed of. Good luck in learning to be a safe pilot!



HappyJack,

I can not disagree with your post, but I don't think it's very helpful. People (including students) fly different aircraft at different weights all the time, so learning a particular stick position at which the stall occurs (and bearing in mind it will also change with flap settings due to the different AoA required, and, I think, power settings due to the effect of the power on the elevator) is not helpful. The only reason I cn think of why it is helpful for a PPL student to know that the stick position is important in determining when the stall occurs is because, as you rightly say, some forward movement of the stick (assuming it's not an inverted stall) is required on the recovery. But the aim of the exercise we teach PPLs is to recover with minimum height loss - and to achieve minimum height loss, more is required than simply moving the stick forward.

The "Falling Leaf" is of very little benefit to PPL students, and has been discussed enough on this forum recently to not need to be discussed again.

FFF
--------------

[HappyJack260]

1972,
I can not disagree with your post, but I don't think it's very helpful. People (including students) fly different aircraft at different weights all the time, so learning a particular stick position at which the stall occurs (and bearing in mind it will also change with flap settings due to the different AoA required, and, I think, power settings due to the effect of the power on the elevator) is not helpful. The only reason I cn think of why it is helpful for a PPL student to know that the stick position is important in determining when the stall occurs is because, as you rightly say, some forward movement of the stick (assuming it's not an inverted stall) is required on the recovery. But the aim of the exercise we teach PPLs is to recover with minimum height loss - and to achieve minimum height loss, more is required than simply moving the stick forward.
FFF
--------------
POWER SETTINGS WILL NOT CHANGE THE STICK POSITION REQUIRED TO GENERATE A STALL.
The reason why I'm banging on like this is that I agree will all the comment about it being preferable not to get into a stall in the first place. And if you know the stick position where this occurs, you can avoid this. Most students and many PPL's flying, say, a 152, two-up, don't know this. And I think there was a case of a DC-10 in South America a few years ago, which deep stalled into the ground from 20,000 feet with the power full on and the column fully aft, past the stall stick position As I said, when it comes to recovery, you need power in to give you the speed to prevent or recover your height loss. But it's stick position, not power settings, that caused the stall in the first place.

I can't comment on how this applies to a fly-by-wire aircraft such as the F-16 or the Airbus. But this applies for GA aircraft, certainly.

Have a read of this article in the CASA Flight Safety Magazine from 2000:

http://www.casa.gov.au/fsa/2000/sep/FSA34-35.pdf

[homeguard]

The application of rudder for stall recovery is not to prevent further 'wing drop' but to prevent FURTHER YAW!
Having recovered from a stall and speed gained the wings should be levelled with the horizon BEFORE adopting the climb.
I too have my students maintain the aircraft in the stall in order that they have the full knowledge of the symtoms of the stall and the characteristics of their particular aeroplane during the stall. They will then better understand the actions that are required for recovery ie; the 'standard stall recovery' as we know it modified for the best action for a particular type.
Throughout all stall training emphasis must be on relaxing the student and removing fear. Fright and ignorance being their biggest hazard which will most likely to lead to an unsuccessful recovery when it matters.
I cannot understand how a properly conducted lesson should lead to an unrecoverable spin.

[bogbeagle]

Happy Jack,

I hope that this doesn't upset you...please don't bite.....I'm afraid that you've got it wrong. Dan Winterland is correct.

Both loading and power (or rather, propwash) affect the stick position at the stall. If it were not so, we'd just do as Langesweische suggests and fit 10 cents' worth of wire to the joystick, limiting its movement and making aircraft unstallable and very safe.

[foxmoth]

To me if you are flying looking at the stick position you are looking in the wrong place! The time you are most likely to stall is when you have your head out the window concentrating on something else, so you need to recognise a stall from cues other than stick position, also, how many control colums have a "position" indicator - most are just somewhere in the middle of the cockpit with little to reference them to.

[HappyJack260]

Don't know about you folks, but since there's not a lot to look at in the cockpit of a Pitts, looking outward is the only place to look, for me. You don't need to look at the controls in order to tell where they are - that's what feel - eg, the angle of your wrist with your hand resting on your knee - should tell you. If you know where the column/yoke is at the point of stalling, you can tell how far you are away from that.

Having an aircraft that cannot stall - thanks to a piece of wire across the back of the stick - would be unfortunate - it would make landings very much harder, because that's when you want to stall. In an aerobatic aircraft, also, there are times when you want to stall the wing - such as in the entry to a flick roll, or spin. I can tell you that the stick position is the same for a spin entry, horizontal flick roll or a flick on a 45 degree upline.

Phil Unicomb - in the article I linked to - explains this much better than me - but the concept does work. I know, I've tried it. All I can suggest is that you, who don't believe me or Phil Unicomb's article, get into an aircraft, get in the air, and try it for youself. Preferably with an aircraft certified for spinning; preferably not an Airbus 320 full of passengers.

Here's the link again to that stalling article:http://www.casa.gov.au/fsa/2000/sep/FSA34-35.pdf

[HappyJack260]

Oh, and just to add to my last post - here's an invitation to the doubters - if you can make it to Sydney - come up with me in the Pitts S-2C and we'll test the theory and see who's right.

[Dan Winterland]

Having just read the article, I think in his attempt to simplify the process the author has made assumptions which are either not strictly correct or misleading.

Firstly, he tries to explain the function of stalling by linking the angle of attack to the elevator position. Although the angle of attack is controlled by the elevator, it is not a function of it. In many cases you can link a stall speed to a stick position, but not all. 'Stall stick position' will change on various circumstances. For example, try the difference in stick position between the clean and approach configuration in a Rallye.

He also mentions that a steep turn of 60 degrees will not change the stall speed. If descending at 1g this would be the case, but if you were to maintain level, you would have to pull 2g. If your 1g stall speed was 44 knots, at 2g it will be 61 knots.

Leveling the wings with rudder? NO!!!!!! Use rudder to prevent further yaw - and that only. This concept should have been eradicated years ago.



FYI, the DC10 has swept wings which have different stall characteristics to GA aircraft. An A320 stick selects a g loading it pitch and returns to neutral when the selected loading is 1g. It will be in the same position at any phase of flight at 1g, but the safety systems won't let you get near the stall anyway.

[HappyJack260]

He also mentions that a steep turn of 60 degrees will not change the stall speed. If descending at 1g this would be the case, but if you were to maintain level, you would have to pull 2g. If your 1g stall speed was 44 knots, at 2g it will be 61 knots.

Set the aircraft up in S&L flight and without altering the fore and aft stick position, roll into a 60 degree bank. You'll go into a spiral descent, but stay at 1G. The G forces don't increase unless you make them.

If you were to try to maintain level flight, you would have to pull 2g - so your stall speed would go up - agreed.

The reason that you might stall, though, is not that you're experiencing 2g but that you've moved the stick back far enough to enable you to pull 2G, possibly through the stall stick position.

An Airbus' computer may determine how to respond to control inputs in order to keep the aircraft out of the stalling part of the envelope. GA pilot's don't have that sort of hardware. But we can discover the stall stick position and resolve to determine control inputs to keep it away from that position. Unless, of course we want to stall the aircraft - such as in a landing or during aerobatics.

And going back to this "control yaw with rudder" vs "pick up the wing with rudder" argument, I seem to remember some very early lesson on the secondary effect of controls. Surely the point is not about which the use of rudder is doing, so much as what is the outcome?

A spin occurs when one wing is stalled, losing lift and increasing drag and the other accelerates as a result, gaining lift, in a self-perpetuating cycle. The use of rudder arrests that cycle and the restoration of matching airflows over each wing brings the aircraft back upright. The reason we don't use ailerons in a stall, is that to do so creates additional drag on the stalled wing and reinforces the cycle.

[HappyJack260]

Both loading and power (or rather, propwash) affect the stick position at the stall. If it were not so, we'd just do as Langesweische suggests and fit 10 cents' worth of wire to the joystick, limiting its movement and making aircraft unstallable and very safe.

I've not flown them much, but I seem to remember that Piper achieved something similar with the Cherokee, by limiting the elevator authority such that it tends to mush rather go into a fully developed stall, preumably due to a lack of elevator size.

The Eagle, with its canard/staggerwing biplane (take your pick) configuration is also designed to make stalls impossible, by ensuring (I believe) that the front wing stalls before the main wing, causing the nose to drop and restoring airflow over the main wing.

[Alogan]

I'm having flying lessons at the moment so this thread makes interesting reading. I've had just over 6 hours and did my first stalls last lesson. I first watched, and then flew into and recovered myself from stalls with "clean" and "full flap" configurations in a C152. These stalls were all with the wings level and power off. I was taught to recognise the stall, and lower the nose below the horizon once it occurred, applying full power at the same time and levelling off once the airspeed had recovered to 60 knots. The height loss using this method was about 200 feet with both aircraft configurations. This method of stall recovery seems to be broadly correct, but some posts on this thread have advised doing things differently (i.e. not lowering the nose below the horizon, not applying full power at the same time).

Although there are some seemingly contradicting arguments in this thread, can I take it that the general principles for stall recovery are:

1) Move the nose down (using elevator) to an unstalled attitude (which can be recognised by loss of buffet), but not any lower (in order to minimise altitude loss)

2) Apply power smoothly once attitude is lowered and buffet removed (or is it apply power smoothly and simultaneously with lowering of nose?)

3) Use rudder to prevent yaw during above actions (but not to correct any wing-drop)

4) Once wings unstalled and airspeed sufficient, use ailerons to align aircraft with horizon (if wings not already level)


Is this correct? Having read about accidents caused by picking up a dropped wing with rudder long before I started lessons, I have never used rudder to pick up a dropped wing, even though I am aware that roll is the secondary effect of rudder (instead using the ailerons). However, I am also aware that using ailerons in or close to the stall in an attempt to pick up a dropped wing can actually make that wing drop further by stalling it (due to the increased attitude of the lowered wing with the "down" aileron).

So I take it that you don't use either rudder or ailerons therefore to pick up a dropped wing in a stall, and instead ignore a dropped wing (or any increasing wing drop?) until the stall recovery is complete, when aileron can be used to pick it up?

Any comment and correction would be appreciated.

[FlyingForFun]

Alogan,

Yes, it sounds like you have exactly the right idea. If you do in the air exactly what you've described in your post, you should get plenty of praise from your instructor.

There is a danger for people with little experience, such as yourself, when reading this thread: many people have said many things which, although correct, do not apply in every situation.

For example, you mentioned not lowering the nose during the recovery. I think that what you have picked up on specifically relates to a recovery from an incipient stall in a light twin-engined aircraft - these aircraft have sufficient power that, from an incipient stall, this recovery technique will work fine, because the forward pressure on the controls necessary to maintain the attitude, and the resulting decrease in angle of attack, are sufficient to remove the symptoms of the approaching stall.

Although the instructors and other experienced pilots on this forum can use their experience to understand why this technique (and others that have also been discussed) might not be appropriate for all aircraft, or why a technique might be technically correct but not using the most appropriate cues, and so on, it is very difficult for someone with very little experience to see these subtleties.

Therefore, for any other students who are following this thread, I would suggest reading Alogan's post and ignoring the rest of the thread!!!

FFF
-----------

[hugh flung_dung]

FFF - an excellent reply!

Alogan - you've got it spot on! There has been a lot of nonsense in this thread - stick to the standard patter that your instructor is (hopefully) using:
"Stick sufficiently far forward to unstall the wing (ailerons neutral), full power, prevent yaw with rudder. When unstalled, level the wings with aileron and smoothly pitch to put the cowling on the horizon then raise flaps and pitch to the climbing attitude as speed increases".
Note that there is no reference to the horizon in the first part of this patter, only that the wing is unstalled.

You ask:So I take it that you don't use either rudder or ailerons therefore to pick up a dropped wing in a stall, and instead ignore a dropped wing (or any increasing wing drop?) ...
Absolutely!!! As soon as you unstall the wing it will stop dropping and you can then use aileron to level the wings.

HFD

[BigEndBob]

I think the use of rudder depends on the severity of the wing drop.
Take a typical worn out Cessna 152 with a bit of hanger rash.
1500 rpm, 2nd flap, back to stall and most Cessna 152 react as though they have had the left wing (usually) chopped off.

Recovery
1/ opposite rudder (step on the wing)
2/ stick forward
3/ smoothly apply full power
4/ centralise rudder as airspeed increases towards 60
5/ roll wings level to nearest horizon
6/ pitch to +ve climb and raise flap
With practise altitude loss less than 100 feet.

If nothing else the exercise serves to frighten a student into the consequences of stalling. Let the student have a go, they will apply opposite aileron, making the situation worse, let them, be ready to raise the flap! What happens is what most observers see when they describe the aircraft spinning down in most accidents, actually a tight 'graveyard' spiral. Too much practise may give the student too much confidence that he could handle this type of stall situation. The emphasise should be on pre stall recovery.

Recovery
1/ at stall warn smoothly apply full power
2/ ease stick forward to reduce a of a
3/ roll wings level if banked
4/ establish +ve rate of climb.
This can be done quite quickly by going from one stall attitude to another each time practise the above recovery.
Most of all know your aircraft, some have pre stall buffet, some don't (C152).
Multi piston benefit from slipstream effect over the wings to generate lift on recovery. Larger aircraft have angle of attack sensors, so i suppose they are linked to the flight computers to prevent stalls?
Also good demo. use the half mill rule as a wing and play with it under a running tap, to demonstarte the breakaway of flow over a wing.

[Alogan]

OK thanks for the replies.

Angus

[bogbeagle]

try this Happy Jack.

1.....get your hands on a 150, or similar..take a pal along.

2.....fly at the edge of the stall at a low power setting, then concentrate on holding the control column in a fixed position.

3.....have your pal apply full power


I think you'll find that, although the stick position is fixed (by you), the aircraft will briskly transition from an unstalled condition to a stalled one.

[HappyJack260]

try this Happy Jack.
1.....get your hands on a 150, or similar..take a pal along.
2.....fly at the edge of the stall at a low power setting, then concentrate on holding the control column in a fixed position.
3.....have your pal apply full power
I think you'll find that, although the stick position is fixed (by you), the aircraft will briskly transition from an unstalled condition to a stalled one.

So when you say, "at the edge of the stall at a low power setting" are you saying that the aircraft is not quite stalled but that addition of power causes a stall?

[FlyingForFun]

HappyJack,

You have understood bogbeagle correctly. This is type specific, but in broad terms what will happen is this.

The elevators produce a downwards force, which causes a pitch-up moment. (This is cancelled out in steady flight by other forces, such as drag and lift.)

With the aircraft close to the stall, stall warner going and possibly even some light buffet, apply power whilst holding the control column still. The increased airflow over the elevator will cause an increase in the amount of (downwards) lift produced by the elevator. This in turn causes the aircraft to pitch up, increasing the angle of attack on the wings, and causing what was originally an incipient stall to turn into a fully developed stall.

This is the theory. I've never tried it in practice as bogbeagle suggests, although I might give it a go. I don't know if bogbeagle has ever tried it?

FFF
--------------

[Uncle Ginsters]

BigEndBob,
Recovery
1/ opposite rudder (step on the wing)
2/ stick forward
3/ smoothly apply full power
4/ centralise rudder as airspeed increases towards 60
5/ roll wings level to nearest horizon
6/ pitch to +ve climb and raise flap
With practise altitude loss less than 100 feet
I would suggest caution in using stage 1/ of this method. This may work some of the time in a 152 but on many ac applying rudder while the wing is stalled will only serve to create autorotation and worsen the situation. The fact that the wing has dropped does not change this. The fact is that the wing is stalled (by definition, above alpha.crit) and you are applying a yawing moment. The AOPA Stall/Spin review (http://www.aopa.org/asf/publications/topics/stall_spin.html) has some interesting stats/comments on what happens when you make incorrect recovery actions.

The priority in Stall recovery must be to get the wing flying again, so simultaneous application of full power and forward elevator(til buffet stops) should be the first actions. Unless your AFM suggest something different.....

Uncle G

[foxmoth]

There seems to be a suggestion creeping in here that you should not prevent further wing drop in a stall with rudder, whilst this is fine in some aircraft there are others (anyone stalled an Emeraude?) where if this is not done instinctively you can end up on your back, so I would much rather see this taught as standard. I have flown many types and have not come across any that this causes a problem on, but as said, there are aircraft that not preventing further wingdrop will cause a problem. (and yes, the aircraft was in balance at the stall!!). Of course what I am not advocating here is the picking up of the wing with rudder.:hmm:

[homeguard]

Foxmouth
Lets make it clear and succinct.
To prevent yaw will in it self prevent the stall becoming a spin. (you must be yawing to be spinning). Following the initial 'wing drop' the correct use of rudder will be to prevent yaw or any further yaw which gives to the secondary effect of roll / slip, further yaw and further roll/slip/yaw and so on. You are not controlling roll with rudder but rather preventing the cause of it.
FFF
I'm sure it is a slip of the tongue. The four forces; pitch down = Lift and Weight. Thrust and Drag = pitch up. Therefore the pitch down moment of the tail plane is primarily balanced by Lift and Weight. Weight becomes dominent at the stall causing a safe pitch down movement.

[foxmoth]

HG,
No problem with what you say here, just that there seems to be a drift towards not using rudder at all during the stall.

[Rosanna]

there are aircraft that not preventing further wingdrop will cause a problem. (and yes, the aircraft was in balance at the stall!!).

SF260 is one of these... if you don't control yaw with rudder it always drops a wing and starts a spin!!!

Ciao!!!

Rosanna

[FlyingForFun]

I'm sure it is a slip of the tongue. The four forces; pitch down = Lift and Weight. Thrust and Drag = pitch up. Therefore the pitch down moment of the tail plane is primarily balanced by Lift and WeightNo splip of the tongue, homeguard, but perhaps I didn't make it clear.pitch down = Lift and WeightGenerally, the CofG is in front of the CofP. This causes pitch down. The downforce from the elevator causes pitch up, which counteracts (some of) the pitch down moment from the CofP.

As you correctly say, the thrust/drag couple causes more pitch up too, but I wasn't discussing that. If you add power, the change to the thrust/drag couple will cause the aircraft to pitch up, but very little change in the AoA because it will cause a rate of climb, or a reduced rate of descent, too. That's why I'm not bringing the thrust/drag couple into the equation.

However, as well as providing a pitch up due to the thrust/drag couple, adding power will also increase the (downwards) lift from the elevator - and this will cause a change in the AoA, and therefore, according to my understanding, a change in the stick position at which the stall occurs.

FFF
-------------

[bogbeagle]

FFF,

Yes, I have tried this. Works well with the T67, too. Even the humble PA-28 starts to become quite unmanageable when you do this.

Then only machine that I have ever flown which probably wouldn't behave this way is the Thruster. If I recall correctly, the application of power in this aircraft produces a strong nose-down moment. Haven't tried it in the Thruster, though.

Never flown a Pitts, neither, but I would expect it to react as the 150.

Certainly, everything that I've ever attempted to stall, flick, spin, has entered said manoeuver much more easily with power applied. I'd bet that a Pitts does, too.

Never stalled an Emeraude, but the Cap 10 is the same animal (I think) in a different guise. Stall is crisp, but recovery is no different to any other machine of which I have had experience.

cheers, bogbeagle

[1972]

In reply to FFF and Alogan...

FFF, thanks for the reply to my previous post, your advice was greatly appreciated. Sorry it took so long to respond.

Alogan, I am a VERY long way away from being confident and competent at this exercise (!!!) as I have yet to complete all the stalls. (Clean were okay, flaps weren't - see my earlier post if you're interested). My FI drilled it into me that while a maximum 200ft loss of altitude was deemed to be perfectly acceptable, he wanted to see me manage 100ft losses - if not nearer 50! I guess that's to make you recover quicker at lower and more critical altitudes? Did your FI say anything like this to you? Anyway, keep up the good work. Sounds like you're getting to grips with the dreaded stalls better than I!

[Alogan]

1972,

Thanks for the encouragement - hope you get to grips with them quickly.

No, my FI didn't specifically stress aiming to lose 100 feet or less - in fact when he demonstrated the stall recovery he lost about 200 feet himself, although that was perhaps due to the fact that he didn't recover from the stall immediately, but held the aircraft in the stall for a few seconds so that I could feel what the stall was like and observe the high nose-up pitch and altitude loss. I expect that I'll be doing a lot more stalls (that was only an introduction really), and perhaps then the emphasis will shift to minimising height loss.

I found doing stalls fine (I had expected them to be more dramatic), and the recovery procedure quite natural, but then I've only done very simple stalls in straight and level flight. Having read this thread, I should be aiming to lose less height and I've got a lot still to learn. Hopefully I'll be able to do some more stalls soon, so that I'll be able to put what I've learned here into practice.


Angus

[1972]

No worries Alogan. Thankfully it sounds like your stalls were less eventful than mine.

Despite the early stall-warning 5kts prior, it's still difficult to predict - or recognise at first - exactly when the stall kicks in. Unfortunately I wasn't quite S&L when we got the bugger to stall!

I'm sure I'll get to grips with them soon. Just need time, practice & more bottle. Damn that bloody wing-drop!

[homeguard]

1972
Don't let the 'wing drop' as it is called worry you so much. Current Certificates of Airworthiness require that the wing shouldn't initially drop by more than 30 degrees which is the normall turning angle of bank used. However if nothing is done the further effects of yaw leading to further roll and so on takes place.
An interesting experience for you if your Instructor agrees is to simply allow this to happen but simultaneously lower the nose to gain speed. the wing should very quickly pick up but will not increase in angle very much. You will not have recovered with minimum height loss but you will gain some confidence in your aeroplane to then accept the 'Standard Stall Recovery' technique training you are receiving.

[1972]

Excellent, thanks for that homeguard. Your advice is noted, and I'll run your suggestion past the FI.

He thought we exceeded 30deg AoB as I'd wrongly used aileron to correct... like a plonker! We both agreed I needed to give stalls a rest for an hour or two just to build confidence in other areas (successful so far) before going back and finishing stalls off.

I'm very much a believer in the phrases "get right back on that horse" and "what doesn't kill you makes you stronger" (!) and you're right, I must experience it again (with said technique) to become confident in the aircraft & the controls.

Will post back with news on how it goes. Thanks again homie for the suggestion and moral support.

Apologies to others for hijacking.

[Uncle Ginsters]

Homeguard, couldn't agree more, old chap.
CofAs include stall performance and as said above,Current Certificates of Airworthiness require that the wing shouldn't initially drop by more than 30 degrees
...but the emphasis there should be on the word initial. Unless the wing is unstalled without delay, then that initial wingdrop could become further wingdrop which might make some PPL eyes water somewhat, at the least :eek: (see thread on spinning from finals turn)
Trying to pick up the wing (as prescribed above) will not unstall the wing and therefore there will still be a chance of the wing dropping again.
If you simply action the stall recovery with simultaneous full power and forward stick until unstalled then there is zero chance of further wingdrop. Is it really that difficult? :ok:

Uncle G

[Dan Winterland]

And don't forget that it's at it's certification. A thirty year old Cessena 152 Aerobat will probably not have the same stall characteristics as the originally certified airframe.

I one instructed at a school which had 15 identical but very old airframes. One aircraft rolled to about 75 degrees to the left in a straight 1g stall.

[7gcbc]

I one instructed at a school which had 15 identical but very old airframes. One aircraft rolled to about 75 degrees to the left in a straight 1g stall.

identical except for rigging differences

I find this thread very illuminating. People are talking about picking up wings with rudder and 112hp engines causing the aircraft to rotate around it's longitudinal axis with the controls having no effect ....

so can I ask, adding power to the 75 degree staller, what would happen if the left wing was down and the prop rotated clockwise (as viewed from the pilots POV).

Aerilons would indeed be fun then, espec in a 152 sans signifigant dihedral don't you think ?

[Dan Winterland]

What would happen? Very little actually. The aircraft's prop rotated the other way and it only had 145HP. (if I mention it's a taildragger - that should tell you what it was!)

If you moved the control column centrally forward until the buffet stoped and simultaneously applying full power while preventing further yaw with rudder, and only when the wings were unstalled (i.e. no buffet present) level the wings with aileron and then pitch to the level attitude there was no problem. This is the standard stall recovery tought by that organisation which is the same throughout the world - more or less. And if the prop had been rotaing the other way, the torque reaction would have made very little difference to the amount of roll at the stall.

For anyone also reading this, wing drop at stall is not usually a problem. It may be alarming, however, you must not attempt to correct it until the wing is unstalled. Any attempt to correct it while you still have buffet, with ailerons or with rudder will probably delay the recovery or initiate a spin. I emphasise again that ailerons should only be used once the wings are unstalled.

There is little chance a 145HP engine is going to rotate the airframe around the prop at the stall. Prop slipstream will have more of an effect and this should be easily controllable with the rudder. The most powerful prop aircraft I have instructed on had a 1200hp engine and there was no 'torque' problems with this type either.


The airframe I mentioned was a bit of a rogue. The rigging had been checked on numerous occaisions but the wing still dropped. (This type typically had a 30 degree wing drop anyway). We tried to avoid using this airframe for the early exercises as the roll at the stalll would be alarming. But it was ideal for more advanced students. The instinct would be to apply aileron, the downgoing wing would have it's angle of attack increased, the stall on this wing would deepen and this aircraft would autorotate. A useful learning exercise, bearing in mind this was a military school and the students would be flying aircraft with much less benign handling than the Chipmunk later in their career (Ooops, gave it away!).



I see from your profile that you fly taildraggers from Sydney. Are you also Happyjack260?

[HappyJack260]

I see from your profile that you fly taildraggers from Sydney. Are you also Happyjack260?

He's not me. I'm not him. We've not met but we both fly from the same field, Camden - he's flying a Pitts S-2B registered VH-TKV and I'm flying a Pitts S-2C (registered VH-JAX - geddit?). Interesting that there are 3 x S-2B and 3 x S-2C Pitts in the whole of Australia and we end up with 33% of the combined population in the same place.

BTW, anyone in the Sydney area want to do a formation rating in a Pitts?

[john_tullamarine]

... does a Navajo which liked to roll to about 120 -130 degrees for full flap stalls count ?

[Lewy-]

I've just been doing a few stalls for my PPL.

I found out that even thought the student or the instructor put the aircraft into a stall deliberatly, doesnt mean that it is controlled, after all, if you had the aircraft properly under control it wouldnt stall.

However, when my instructor demonstrated a stall, it went a bit worse then he hoped for, we had a bad and sudden wing drop, recoverable, but still, very fast and sudden.

So when doing stalls especially with flap, be ready for anything. Wing drops can be slightly worse in bad weather conditions.

[HappyJack260]

I've just been doing a few stalls for my PPL.

I found out that even thought the student or the instructor put the aircraft into a stall deliberatly, doesnt mean that it is controlled, after all, if you had the aircraft properly under control it wouldnt stall.


Not an everyday occurrence for a PPL student, I know, but you can fly an aircraft fully under control and have it fully stalled:
Examples: Snap (Flick) Roll; Competition spin; falling leaf. All everday stuff for aerobatics pilots.

[Dan Winterland]

From the CAA Training Standards Communication 1/2006.

Oscillatory Stalling

In May 2005 an instructor and student were on a training flight when the aircraft was seen to enter a spin and continue spinning until it impacted the ground, killing both occupants. The AAIB investigation stated "Although an unidentified control problem, loose artice or other distraction could not be eliminated as a contributing factor, it is considered that the likely scenario was that the aircraft entered an unintentional spin during an evercise involving "oscillatory stalling".

The term "oscillatory stalling" is not commonly used. No reference could be found in UK flight training publications, by either the AAIB investigators or CAA staff flight examiners. However, from other sources it is understood to describe the practise of maintaining the aircraft in a stalled condition whilst controlling wing drop with rudder.

Two points should be emphasised here: firstly the purpose of the stalling exercises on the PPL syllabus is to ensure that students can recognise the warning signs of the approaching (incipient) stall and the symptoms of the developed stall, and be able to recover safely from incipient and developed stalls. It is not necessary or adviseable, having demonstrated the signs and symptoms, for instructors to hold an aircraft in a developed stall, and students should never be taught to do so for the purposes of this exercise. Secondly, instructors are reminded that the rudder must only be used to maintain balance (prevent yaw) throughout the stalling exercise. The essential components of a spin are wings stalled with yaw and/or roll present. Deliberately inducing yaw with rudder to "pick up" a dropped wing, with the aircraft stalled, is tantamount to setting up for a spin.