PPRuNe Forums

PPRuNe Forums (https://www.pprune.org/)
-   Flying Instructors & Examiners (https://www.pprune.org/flying-instructors-examiners-17/)
-   -   Wing drop at stall (https://www.pprune.org/flying-instructors-examiners/624505-wing-drop-stall.html)

UAV689 11th Aug 2019 19:37

Wing drop at stall
 
thoughts on instructing students to stop a wing drop at stall with rudder?

i personally think its the wrong thing to do. A wing has stalled, so just do the standard stall recovery.

Wing drop is taught as a symptom of stall, so just do the SSR at that point.

Besides, if i want to spin intentionally, I tend to do it by rudder at the stall...! And who knows in heat of moment what direction of rudder they will put in if an instructor is not there...

spekesoftly 11th Aug 2019 19:58

The thread linked below is from many years ago, but you might find it interesting:-

http://www.pprune.org/flying-instruc...op-stalls.html

Kemble Pitts 11th Aug 2019 20:18

Current instructor training is to teach students to unstall the wing (stick forward, enough) whilst adding full power. Once the aeroplane is flying again, only then sort out the roll.

I'm with you on the spin risk, although it is often over-stated, but even so.

Out of interest, current aircraft certification requirements actually demand that the ailerons are fully effective all the way into the stall. However, older aircraft (pre-1960s) might not be so amenable so I think its best to teach students to stay off the rudder and ailerons altogether until the aeroplane is flying again.

Big Pistons Forever 11th Aug 2019 21:51

All ab initio stall training should start with the understanding that the point of the exercise is not to teach you how to stall the airplane, it is to teach you how to recognize the aircraft is about to stall and fix the situation before it does stall. However if you are asleep at the switch then it is important that you learn how to quickly regain control. This should always start with reducing angle of attack by smoothly but firmly lowering the nose and then applying full power. Control of yaw at this point now becomes important as if the aircraft is allowed to yaw then it can spin. Effective use of the rudder is the way to control yaw and thus eliminate the possibility of the aircraft departing in a stall.

Even though modern aircraft certification standards require that the ailerons be effective even after the wing has started to stall, ailerons should still not be used to level the wings until the aircraft is definitely un-stalled

The biggest problem I see with ab initio instruction is the exercise is taught with the aim of generating a good mark on the flight test, instead of showing students the real world scenarios that pilots get into trouble on.

Whopity 12th Aug 2019 07:49


by smoothly but firmly lowering the nose
That may be the consequence of what you do, but the correct teaching is to move the control column centrally forward. That may or may not lower the nose.
The rudder is used to prevent further yaw

Genghis the Engineer 12th Aug 2019 15:42

Hopefully you can open this, which was a fairly extensive research into optimal recovery actions.

https://www.aerosociety.com/Assets/D...urnal/3965.pdf


If that didn't work, try this link:

https://bura.brunel.ac.uk/bitstream/.../Fulltext.docx

It didn't actually look into the absurdity of picking up a dropped wing with rudder, which I think most of us know more correctly by the name "spin entry". It concluded that optimal recovery is simultaneous pitch and power in all singles tested.

G

Whopity 13th Aug 2019 11:25

It was suggested at a FIE standardisation meeting some years ago, by a fairly senior former RAF QFI that the practice of using rudder at the point of stall came from training on the Harvard. When the aircraft dropped a wing, the weight of the engine lead to increased yaw and the use of top rudder in the recovery would minimise the height loss. Unfortunately, this technique was passed on to many new instructors, who were trained in the 60s by FIC instructors who might have been trained on the Harvard.
Following a rather nasty accident in a Slingsby involving "oscillatory stalling" the practice of trying to pick up a wing with rudder was discouraged by the CAA.

Genghis the Engineer 13th Aug 2019 13:33

Given the Harvard's well known reputation for spinning off a stall, particularly if inadvertently stalled in the final approach configuration - that is "interesting".

I just took a look on the national archives website, but unfortunately can't seem to see any A&AEE flight test reports on the Harvard - it would be really interesting to compare that supposition to the published characteristics of the aeroplane.

I did find this webpage with a set of what appear to be wartime USAF training notes for the Harvard....

https://www.t6harvard.com/pilot-stor...nd-manual-pdf/

If you download chapter 5, and go to page 62 you find...


When you recognise the stall, recover by simultaneously apply positive forward stick pressure and opening the throttle to the sea-level stop. Apply rudder pressure as necessary to keep the nose of the aircraft from yawing as it comes down, and aileron pressure, as necessary, to keep the wings level. Normally, additional right-rudder pressure will be necessary to overcome the gyroscopic action of the propeller as the nose is lowered. Allow the nose to continue down to an attitude slightly below the normal cruising speed, straight and level flight attitude.

<snip>

The possibility of a wing dropping during a stall, and the proper corrective action, bears further detailed discussion at this point. Most modern aircraft are so constructed that the wing will stall progressively outward from the wing root to the wing tip.

<snip>

The rudder should be used in such a manner as to prevent the nose from yawing toward the low wing. That is, it should be used to keep the nose attitude straight ahead.
It goes on for several pages after that, but so far as I can see, every mention of the rudder is about either preventing further yaw, or keeping the ball in the middle. It repeats several times what we'd still say now - unstall the aeroplane with elevator, then use the ailerons to roll wings level.

G

Whopity 13th Aug 2019 20:12


The rudder should be used in such a manner as to prevent the nose from yawing toward the low wing. That is, it should be used to keep the nose attitude straight ahead.
Which could have been misinterpreted to mean pick up the wing with opposite rudder. So many old school instructors taught this that it had to have originated somewhere, with a little bit of "Send three and fourpence, we're going to a dance"

Genghis the Engineer 13th Aug 2019 21:19

Might have been on some other type? I certainly agree that it's a bad practice anyhow.

What works on a Tiger Moth?

G

Fl1ingfrog 14th Aug 2019 00:08

We, all too often and unwittingly confuse the central aim of recovery from the stall, with the process. The first aim must be to unstall the wing(s), nothing else.

Applying power will not unstall the wing(s). The rudder will not unstall the wings. In my view it doesn’t matter whether you move the hand control forward centrally or not, what really matters is that you stop holding back.

The aircraft cannot stall on its own; it takes the pilot to do it. So if stalled the pilot must be pulling the control aft. The inherent pitch down moment will be so strong the pilot needs only to relax the back pressure; the aircraft will do the rest. The angle of bank, if any, is irrelevant and should the aircraft be turning, so what.

After unstalling the aircraft and regaining control, then and only then does achieving the minimum height loss becomes paramount. Applying power and levelling the wings is a major part of this of course. Incidentally, with regard to the Harvard an old mentor would regularly refer to how quickly, during stall recovery, you could put a Harvard on its back with too much power if also applied too early.

However, having applied power then control of pitch, roll and yaw will be required with the simultaneous use of all three controls. During the olden days when the CAA had a flight examiner wing an internal argument raged; some saying “the simultaneous use of power and pitch ...” for recovery but this would send others into a state of apoplexy whilst banging the table and demanding hysterically that you must say “pitch and then power...”. The late great Hector Taylor when asked for his view replied: “the simultaneous use of pipowtcher...” was how he said it. He explained that it was the only way he had found to say pitch and power at the same time.


double_barrel 14th Aug 2019 06:56


Originally Posted by Big Pistons Forever (Post 10542735)

The biggest problem I see with ab initio instruction is the exercise is taught with the aim of generating a good mark on the flight test, instead of showing students the real world scenarios that pilots get into trouble on.

Absolutely! It was taught to me purely as a 'task' to be competed without changing altitude or direction. I would like a more real world scenario, eg simulating a slow turn to final in which I am daydreaming, let airspeed fall during the turn and suddenly find myself in a stall with one wing low. I understand that is a common way to die, so it would seem to be worth to build-in the correct instincts for such circumstances.

Whopity 14th Aug 2019 09:13


It was taught to me purely as a 'task' to be competed without changing altitude or direction.
Do you mean to say that you were never taught nor examined whilst stalling in the base turn?

double_barrel 14th Aug 2019 09:57


Originally Posted by Whopity (Post 10544595)
Do you mean to say that you were never taught nor examined whilst stalling in the base turn?

Yes. Only from straight and level with varying amounts of flap.

Kemble Pitts 14th Aug 2019 12:58

GtE

A (properly rigged) Tiger Moth will usually just stalls wings-level withou a wing drop and with a high rate of descent, so unstall the wing and add power and away you go. To be honest, with such a deficiency of aileron its pretty hard to make a Tiger go around a corner anyhow...

On the Harvard you simply unstall the wing, add power and then deal with the (rather large) wing drop. Did that a couple of weeks ago on a re-check ride and it seemd to work just fine.

Whopity 14th Aug 2019 15:19

db

Yes. Only from straight and level with varying amounts of flap.
May I ask which country you trained in?

A few years ago there was an incident in the UK where a Microlight pilot was killed in an accident following a stall. On investigation, it was found that his Training Records had been falsified and that he had not completed the required stall training. The Instructor received a 6 month sentence.
Every test, club check etc that I have ever conducted has involved stalling in the turn, and you have never done this, it is also one of the major reasons for failure.

double_barrel 14th Aug 2019 17:35


Originally Posted by Whopity (Post 10544941)
db

May I ask which country you trained in?.

Not the UK!


BigEndBob 14th Aug 2019 21:45

I have sometimes been with pilots in their LAA aircraft for the one hour with instructor and say to them lets do some stalls.
Usual reply is, they have never stalled the aircraft.
So i ask them, well how do you know what a safe airspeed is on the approach and landing.
Often they say the previous owner said fly it at a certain (too fast) speed.

Lets face it, if a stall and wing drop occurs, the first thing a pilot will do is probably full opposite aileron.
It will never happen in a clinical practise way.

Genghis the Engineer 15th Aug 2019 11:47

Exacerbated by the LAA not historically ensuring a properly populated and checked POH! (Although that does seem to be changing with the latest types.)

G

Kemble Pitts 15th Aug 2019 16:41

Let's be fair to LAA here, you don't need a POH to take your aeroplane up to 5000 ft and see how it stalls clean. dirty, dirty/turning. You need to be taught to fly properly and you'll then understand that stalling is not scary and its a good idea to know how your aeroplane behaves.

When giving people 'biennials' I always get them to stall straight and turning. Most of them gibber when I show them turning stalls (some for stalls of any sort), some actually sweat, and they are often too nervous to really do it themselves with me next to them. I've often had to complete the 'back stick' pull to get the thing to stall as they just can't bring themselves to do it. Maybe that shows a good degree of self preservation but I'd rather they experienced the full stall and practised the correct recovery and made it automatic.

Bottom line is most (GA) pilots are scared of stalling, possibly because most instructors are too. I do my best to overcome this during the biennial '1 hour'.


All times are GMT. The time now is 20:14.


Copyright © 2018 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.