questions on stall recovery

[AhDee]

Hi all,
I am just a rookie on flying. just seen the aviation video stuffs, There is a clip showing a light weight aircraft spinning after stall. I have been told that to recover a stall, i have to pitch down, full throttle and pitch up. but in the clip, the PIC have his control colume all the way pulled out (pitching up) for the whole stall/spinning excercise, then the aircraft returned back to straight and level (rudder should have been used, right?). How come????:confused: :confused: :confused:

Link for the Clip
http://www.najaco.com/aviation/videos/videos.htm

[keithl]

Not sure how much detail you want, AD, so I'll keep it simple and you can ask for more if you need it.

You said "spinning after a stall". It will help if you think in terms of "spinning IN a stall". The spin will continue as long as the a/c is held in a stall - hence the stick held back for the whole of the spin demo. To recover (and this varies in some types), stop the yaw with opposite rudder and move the stick forward to unstall the wings.

Does that answer the question?

[GGCC]

I am just a rookie on flying.

Hello AhDee;

keithl has it right but i would suggest reading (if you havn't) the book "Stick and Rudder" by Wolfgang Langewiesche.

It's all about the basics..................available at Amazon.com

[FlyingForFun]

I can't disagree with the replies so far... but they don't seem to answer AhDee's question, which was specifically asking why, in the video, the pilot has the control column fully aft throughout the recovery.

I don't have an answer to the question (but it's difficult for me to watch the video here at work, so it might be that there's something obvious in it which I've missed). I was told, very recently, that in some types (Robins, I think?) the (non-)standard spin recovery was to keep the stick aft, but I didn't get a chance to ask any more questions about why this is done on these types. It certainly doesn't apply to any type that I've ever flown.

AhDee - I guess you're a current PPL student? Spinning (fully developed spins) is an optional exercise on the PPL course. If this interests you, and your school has a suitable aircraft available, I'd suggest asking your instructor to take you up for a session of spinning.

FFF
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[Saab Dastard]

Ah Dee,

The quality of the video is such that I for one couldn't see what position the control column is in at all stages of the spin.

When the aircraft is spinning, the stick has to be kept back to maintain the spin and at the very end, when the aircraft is wings level and pulling out of the ensuing dive, the yoke is certainly fully aft, as you would expect. Perhaps this is why the yoke seems to be back throughout.

There are several moments around the time that the rotation stops when the view of the yoke is obscured, so the moment that the stick is being pushed forward to assist in stopping the spin is probably also obscured - remember, the yoke doesn't have to be pushed fully forward, just enough back pressure released to unstall the wings, as others have mentioned.

I wouldn't base spin recovery techniques on what you saw on that video - but I bet the cameraman drinks Carling :yuk: !

HTH

SD

[Evo]

I was told, very recently, that in some types (Robins, I think?) the (non-)standard spin recovery was to keep the stick aft but I didn't get a chance to ask any more questions about why this is done on these types


I think Genghis explained at some point - during certification they tried all the variations, and that one worked best.

[Smedley]

The video probably starts with how to ENTER a stall, then recovery technique.

Full foreward stick. then after airspeed has recovered to flying speed, slowly apply back stick until near level flight, then add power to resume cruise.

Violent back stick will induce another, and usually worse, progressive stall.

[keithl]

FFF I refer you to my answer hence the stick held back for the whole of the spin demo

That was an attempt to explain why the stick was held back - i.e. to HOLD it in the spin.

You can see it goes forward for the recovery.

[AhDee]

:ok:

thx a million guys for all your explanations!!

I believe I got the answer from FFF and SD.

Now I know for stall recovering, the PIC doesn't really need to push the yoke all the way forward for decreasing the angle of attack.

Yup I am a PPL Student and just have my flight training started in Australia in my holiday. Unfortunately I don't have enough time for my training to cover stall and spin yet. (just did 2.5 hrs with a Gazelle and I am now up to descending and climbing turns)

Thank you all!!!!
:D

[Sensible]

Don't know if there is a gliding club or whether you can do spins in the country where you live but there is nothing to give more smiles than spinning in a glider.

By the way, the last thing you want in a spin with a power airplane is full power or indeed any power! The airplane would quickly exceed Vne (Velocity never exceed) in the spin and flaps, ailerons and other bits bits would be torn off of the wings and/or the engine would blow due to over revving!

[FlyingForFun]

By the way, the last thing you want in a spin with a power airplane is full power or indeed any powerNot true, Sensible. Depending on the type of aircraft, of course. Adding power in the spin is exactly the way I was taught to fly a flat spin, in an appropriate aircraft. Of course I wouldn't recommend this in any aircraft without flying it with an experienced aerobatic instructor first, as well as checking the POH to ensure it's allowed......

FFF
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[Sensible]

FFF I bow to your superior knowledge Sir, I haven't done flat spins!!:\ :sad:

[FlyingForFun]

Hmm, not sure I'd call my knowledge "superior", having only done flat spins about three or four times, and not for over two years now. Definitely recommended, though, especially if you can get to do them inverted.

Now, I wonder who I can find that's got a proper aerobatic aeroplane that I could "borrow" to get current again???

FFF
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[shortstripper]

Sorry Sensible but to be pedantic ...

it's impossible to exceed Vne in a spin as the aircraft is stalled. However, it is possible in the recovery unless you snap the throttle shut very quickly or use induced drag to limit airspeed. Also if you are not actually spinning but spiral diving you could easily spoil your day!

SS

[Sensible]

Sorry shortstripper but in a glider Vne comes up very very quickly in a spin and that's leaving the throttle closed :D

[John Farley]

Sorry to climb on your back Sensible but that is not the case if the glider is indeed spinning - only if it is in a spiral dive. In fact THE way to check which of these two manoeuvres you are in is to look at the IAS.

Low and not increasing = spinning
High and or increasing = spiral diving

Honest!

[shortstripper]

Sorry sensible

I'm also a glider pilot and you'll find that if you are in a spin you cannot exceed Vne ... a stalled wing no matter how long is in a stable and safe state (unless of course it hits the ground). It is only once you unstall and recover from the spin that you can exceed Vne

SS

[Sensible]

Yes, I have to conceed that it is after the spin has been arrested if that's the word that the airspeed climbs very dramatically. I have to admit that I have never looked at the airspeed whilst in the spin only during recovery to ensure that the Vne is not exceeded or falls to allow the airplane to enter a secondary stall on recovery.

[Saab Dastard]

Mmm,

Interesting.

it's impossible to exceed Vne in a spin as the aircraft is stalled. However, it is possible in the recovery unless you snap the throttle shut very quickly or use induced drag to limit airspeed

Agree 100% - just makes me wonder how quickly a given aircraft will reach its maximum (sub Vne) velocity in a spin, and is the ability to recover from the spin (in the sense of so much kinetic energy that it WILL exceed Vne in the recovery) then independent of the duration of the spin. Assuming the ground has not been contacted!

In which case, it must come down to pilot proficiency to minimise the ensuing rapid increase in speed on recovery.

SD

[FJJP]

Let's be a little careful here. Most of what's been posted is valid. However, You need to get aboard with an instructor ON THE SPECIFIC TYPE to learn about spin recovery. For example, the RAF taught that if you spun the Chipmunk and hadn't recovered by 3000ft you baled out. However, an old, bold, hairy instructor demonstrated the if you took hands and feet off the controls, the ac would fly itself out of the spin.

Each ac has its own characteristics, determined by the ac manufacturer's test pilot. He's the one who determines the ultimate spin recovery technique [correct me if I'm wrong JF]. Usually, the standard recovery technique (throttle closed, full opposite rudder and elevator neutral) will recover you from the spin, but you might find an ac where that is not the case. Also, (althought unlikely in a light ac) you might be in an unusual spin (inverted or flat, for example) and the recovery techniques are substantially different.

[shortstripper]

As often seems the case on this forum, I think we're starting to make things far more complicated sounding than they need to be.

I will repeat that in a proper spin you cannot exceed Vne and as long as you recover correctly and don't dither or panic during the pull out you would be very unlikely to exceed Vne there either. The downward momentum of a fully stalled spinning aircraft of the type us PPL's deal with is likely to far less than say 700'/minute. At the point of recovery you are likely to be pointing pretty nose down but not at great speed. As long as you pull out of the dive promptly you would be very unlikely to get anywhere near Vne on all but the most slippery types.

Providing W and B is correct all civilian cleared light aircraft will recover with the standard recovery action. However, odd things can always happen as all aeroplanes change with age are therefore are not all equal. The trouble is once in a FULLY developed spin FULL recovery action may take a while to take effect and it's easy to think thinks are wrong and panic ... add to this that it's always possible they really are! For instance the Chipmunk needs full forward stick ... and I mean FULL. I'm no Chippy expert but I've heard of people needind to unstrap to get the stick ALL THE WAY FORWARD before it will recover. True, "most" GA aircraft will recover if you take your hands and feet off ... but a trickle of power? a rearward CofG? ect can all stop recovery which in any case would be slower than by positive recovery action.

My advice (take it or leave it) would be to have a go at spinning in an aircraft cleared for it with an instructor happy to show you. Spinning is no great drama, well worth experienceing (even if just to dispel any misconceptions) but it isn't always predictable so just be aware and don't be complacent.

SS

[FNG]

shortstripper, I certainly agree with you that spinning should not be regarded with the awe and trepidation that comments here sometimes suggest, but may I query your remark on the downward momentum of a spinning aircraft of the type which may be encountered by PPLs.

You suggest a figure of less than 700 feet per minute. Did you mean to say 7000? I have no experience of or figures for the most common tourers, but I don't suppose that they would descend in a spin at a rate which is an order of magnitude less than that of an aerobatic aircraft. A Cap 10b, for example, descends 300 feet per turn of spin, and makes one turn every 1.7 to 2 seconds (9000 feet per minute). I don't have my Bulldog notes to hand, but I recall that it too drops like a bomb when spinning. Those who fly other fairly common aerobatic types (Yaks, Pups, Robins, Fujis etc) will be able to offer the figures for their aircraft. Do C152s and PA 28s descend much more slowly when spinning?

At the point of recovering from the spin, the aircraft , which was until a moment ago not a flying machine but simply a heavy object falling from the sky, is travelling towards the ground fairly rapidly, so your recovery from the dive needs to be smartly executed. As you say, no big deal as long as you don't faff about at this point. I very much do not wish to convey to those who haven't spun that it is something desperately hairy and alarming, but it could be misleading to visualise the spinning aircraft as just fluttering gently groundwards like a falling leaf .

PS: I seem to recall reading that stalled canards will falling- leaf all the way to the ground if you let them, but that's another topic. As for descending whilst stalled but not spinning, I can't recall the rate of descent, but remember sharing a moment of hilarity with my instructor during my first stalling lesson, brought on by the nodding-dog effect of holding a Beagle Pup in a wings-level, power-off stall. Well, I thought it was funny, anyway, but, as my mum says, little amuses a fool.

[shortstripper]

Yep you're quite correct FNG ... I was thinking per rotation and muddleing it with descent rate.

SS

[Genghis the Engineer]

Providing W and B is correct all civilian cleared light aircraft will recover with the standard recovery action.

Negative.

Firstly there are some types in use which haven't formally had a spinning assessment (which should be a criminal offence in my opinion, but it has happened in the past). If an aircraft has no formal spinning clearance I wouldn't necessarily assume that it is proven to recover from a spin unless it specifically states that it has in the POH. Some of these types that weren't properly assessed will even have spin recovery actions in the POH that weren't tested on that type (that starts to move into capital offence territory in my book, but again it's happened - although no doubt what is given in the POH was in somebody's opinion the best set of actions to recover). [Flying as pilot in command of anything for which you haven't read and digested the POH is also in my opinion a criminal offence, I have strong views on these things!]

Secondly the "standard spin recovery" is a fiction, it doesn't exist. There is the best recovery for a particular type, that has been properly assessed - it is likely that what many pilots insist on calling the SSR (close throttle, full back stick, full opposite rudder, ease stick forward) will work for most aircraft in most circumstances. But, if that's not what is in the approved manual, nobody but a Test Pilot, flying as part of his job, should be using anything but the POH recovery.

Third, it is often possible to achieve a "less friendly" spin mode through mis-use of controls that falls outside of normal handling. The aircraft SHOULD still recover if it was properly assessed during approval, but protracted or unpleasant recoveries can result. For example, in-spin aileron in a Bulldog, or power left on in a Tucano can both lead to very protracted recoveries (we managed 19 turns once in a Tucano T1 when I was flight testing them at BDN, I could see my career flashing before my eyes over the last couple of turns !).


Also, although I agree that Vne exceedence in a properly executed spin recovery is rare and should be avoidable, Vfe exceedence in recovery from a spin with flaps (say off a simulated finals turn) is very easy to do and can equally lead to a wing overstress.

And finally, deep-stall in a Canard (from my experience of one type) involved a high rate of descent, and slow wing-rocking which could diverge into a gentle but correctable (with aileron) tendency to roll off. Painless enough and probably survivable if it had continued down to the ground from the descent rate, although I'd not be in a hurry to prove that experimentally.

G

[shortstripper]

Gengis

When I said all civilian cleared aircraft I meant all those cleared to spin. I realise it would have been better to put "should" recover rather than "will" recover, but I did go on to say that things don't always go as planned as not all aircraft are equal (even within type). I also hinted that a little control input here or there ... "a trickle of power?" or rearward CorG could stop recovery.

I realise this is a safety issue and we must be careful not to mislead ... but gimme a break!
:ugh: I don't have the precision of wording that a lawyer may have but I did try to say that some caution should be excerised.

Also

I agree with what you say about exceeding Vfe. So if you want to add more gotchas, how about gliders pulling out of high speed dives with open airbrakes. It's possible to break a wing at a lower g than published due to stress around the brake boxes.

In all I really think the more complicated and confusing we all make this sound, the more it adds to the fear many have of stalls, spins and any divergence from a percieved safe flight envelope. All I started of by saying is that you can't exceed Vne in a true spin ... and I stand by that. What you do to kill yourself by not recovering or by recovering badly is your problem :p


SS :ok:

[Shaggy Sheep Driver]

the RAF taught that if you spun the Chipmunk and hadn't recovered by 3000ft you baled out. However, an old, bold, hairy instructor demonstrated the if you took hands and feet off the controls, the ac would fly itself out of the spin.

I wouldn't like to rely on that in our Chippy:( It might work if the spin has only just been entered, but as another poster said, Chippys might need full forward stick in the recovery (there is a madatory cockpit placard to that effect) - but only from well developed spins (probably 5 or more rotations). From a 2 or 3 turn spin the aeroplane has, in my experience, always come out ith the standard 'power off, ailerons central, full opposite rudder, stick forward until the spin stops, centralize rudder, recover from dive' technique.

I can't see it being neccessary to unstrap to acheive this full forward movement unless the pilot is vey slight with short arms. The danger is that the stick goes forward quite easily then stops - and unless you know different it's easy to assume that that's the forward stop. It's not - it's air loads on the elevator that have to be overcome with a stronger push (I've heard it can take 2 hands, but I've never experienced it being that bad). It's that last push that un-spins the aeroplane.

Regarding rates of descent in spins, I did some training in our Yak52 with Skytrace at Halfpenny Green - flat and inverted as well as 'normal' spins. ROD in the flat spin was said to be the same as a free fall parachutist - about 120 mph straight down. But not much airspeed on the clock.

SSD

[Genghis the Engineer]

I accept that it's making things complicated, and I am happy to say that anything certified for deliberate spinning should always come out, using the handling advice in the POH.

Spinning, within authorised limits, in an aircraft approved for the purpose, and recovering using the handling advice in that aircraft's approved manual(s) is indeed nothing to be afraid of.

I'm happy to agree on these points, because one of the things that I do for a living is making sure that this is true.



But to say that a spin is nothing to be afraid of is I'm afraid
rather against much of my personal and professional experience - whether it's the 19 turn frightener (which should have recovered in 6) in a Tucano, spending several months of my life about 10 years ago investigating why certain Lycoming engines kept stopping during developed spins, discovering an unknown spin-entry mode (in an aircraft that hadn't had any spinning assessment during certification) when helping AAIB investigate a fatal accident about 6 years ago, or the loss of a well regarded colleague (and an extremely experienced pilot) in a T67 spinning accident last year.

G

[shortstripper]

If I came across as saying you need have no fear of spinning then I'm sorry, that's not what I meant. Errr actually Gengis you contradict yourself in your last post if you read it again.

As for not being afraid of spinning, I am. However, there is fear and there is fear! Yes be afeared of spinning but not in an unrational way. Be afraid of the unexpected stall/spin but not so afraid as to panic and freeze. Be afraid of the intended spin that doesn't want to recover, but not so afraid as to loose rationale and the ability to think.

Don't be afraid to ask to have a spin demonstrated and recovery action taught. It might just give you the edge if you one day get into a sticky situation.

The worst fear is the fear of the unknown and only way to dispell that kind of fear is to take the unknown element away. That is not to say be flippant or totally unafraid as that is plain daft. We live in a dangerous world and flying is by no means safe.

SS

PS Also don't be afraid to bow to experience, to wit I humbly do as I am by no means an authority on the subject and merely comment on things based on my own limited experience
:\

[Genghis the Engineer]

I don't think I was contradicting myself - what I was doing was differentiating between the "known" spinning condition, and the "unknown spinning condition" (which incidentally includes, in my book, using any "standard spin recovery" that isn't included in the operators manual).

I certainly agree completely with you that all pilots should have a reasonable knowledge of how to identify the spin and deal with it; I think remaining in ignorance (and fear!) of what should in a properly sorted aeroplane be a known and predictable event is extremely unhelpful. So yes, I do agree that any pilot without a reasonable knowledge of the spin should seek some proper training in it.

G

N.B. Yes, some of the logic in my last post was a little clumsy. Something, somewhere, kept crashing when I tried to edit it, and in the end I gave up and got on with some real work.