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Stall Spin Awareness/Recovery

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Stall Spin Awareness/Recovery

Old 20th May 2012, 16:42
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I firmly believe that instructors who are not competent aerobatic pilots should not be out spinning with students because they will not have a true understanding of spin dynamics, effective of controls in fully developed spins, and may not be able to recover if the aircraft does something dangerous.
Actually that's something I hadn't even considered. Excellent point!

but as far as most PPLs are concerned it IS FULL power on recovery.
Foxmoth I wasn't suggesting otherwise, just that aggressive control inputs aren't required to unstall an aircraft. Adding full power is where the extra control forces come from. If a PPL doesn't understand that then they will quite likely over-control when attempting unusual attitude recoveries.
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Old 20th May 2012, 16:48
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Originally Posted by Silvaire1
Speaking of skids, would anybody (BPF?) like to comment on recovery from a power off stall in a slipping turn, with excess top rudder, in comparison to a power off stall from a skidding turn with excess bottom rudder (and subsequent spin). Traditional training says one is deadly, the other relatively benign. My experience is in straightforward stalls and spin entries from wings level.
There isn't any difference. At the first indication of a stall it is full power and stick forward (together) and full rudder against the yaw, recover to the wings level climbing attitude.

Last edited by Big Pistons Forever; 20th May 2012 at 16:50.
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Old 20th May 2012, 16:54
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Foxmoth I wasn't suggesting otherwise
If you need power then add power. If you need full power than use it.
could certainly be taken this way. For most PPLs, if they recognise that they are getting near the stall their recovery needs to be instinctive and correct, as far as recovery from unusual attitudes goes, this is trained as a seperate lesson and any overcontrolling addressed at this stage (not often a problem in truth).
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Old 20th May 2012, 17:34
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From my very limited experience of a few lessons in a Citabria, a "slipping stall" is a lot more benign than a "skidding stall", in fact it somehow felt almost more stable than a coordinated stall, and not at all spin-prone. Of course, I might just not have tried often and/or well enough (in addition to the Citabria being a very docile airplane).
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Old 20th May 2012, 17:39
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The bottom line is simple the aircraft, must never be allowed to be in a skid especially close to the ground. No amount of spin training will save you if you stall a skidding aircraft at or below circuit height........
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Old 20th May 2012, 19:38
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skid = slip = sideslip.

sideslip + high AoA = potential spin entry.

Spin entry = sudden and significant height loss, regardless of subsequent actions.

sudden and significant height loss close to ground = crash.

G
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Old 20th May 2012, 20:17
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Foxmoth, a couple of pages ago you opined that my description of a fully held off landing as a stall a few inches from the ground is "a commonly held misconception!"

Please elucidate!
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Old 20th May 2012, 20:19
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. . . and yet it is perfectly safe to sideslip until just before touchdown. Isn't it routine for unflapped aerobatic aircraft (with no washout!) to sideslip to land?

At height, trim your aircraft to fly at your normal approach speed, in a slight descent if you like, & apply rudder. You will get plenty of yaw & a little roll as a secondary effect. Do the same at a few knots above the 1g stall speed & you will get a little yaw & lots of wing drop. The retreating wing has a slightly higher AoA than the advancing wing but for it to stall & drop the wing has to be very close to the stalling AoA in the first place.

A skidding turn, in itself, is no more dangerous than a slipping turn but it is an indicator of an overloaded pilot who is behind the aircraft. Typically they are looking down the wing at the landing area, underbank in the turn but pull back on the controls and then feed in the rudder to hurry the turn along.

If you maintain a normal airspeed & AoA it is perfectly safe to fly a slipping turn into a slipped final approach.
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Old 20th May 2012, 20:46
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I firmly believe that instructors who are not competent aerobatic pilots should not be out spinning with students because they will not have a true understanding of spin dynamics, effective of controls in fully developed spins, and may not be able to recover if the aircraft does something dangerous
Wow!!!! That is very telling against the idea of recovery at incipient and no spins as not even the instructors are up to it or properly trained as pilots??

pace

Last edited by Pace; 20th May 2012 at 20:48.
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Old 20th May 2012, 20:50
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With a strong crosswind I sideslip to touchdown - on one wheel first. (Taildragger)
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Old 20th May 2012, 20:50
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Foxmoth, a couple of pages ago you opined that my description of a fully held off landing as a stall a few inches from the ground is "a commonly held misconception!"
There has a lot of discussion on this over the years, I have done a lot of stalling and landed many Tailwheel aircraft, Stalling on most aircraft I first reach the light buffet as the indication that I am approaching a stall, the only times I have had light buffet on landing has been when I have got it wrong - and even this is not actually AT the stall, just incipient. You will also find in most aircraft that you can land tail first - so how can a proper 3 pointer be stalled? If you get it right though, a good three pointer will have lots of drag and you will be decelerating and running out of lift FAST as you touch down.

Last edited by foxmoth; 20th May 2012 at 21:18.
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Old 20th May 2012, 21:21
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Originally Posted by Pace
Wow!!!! That is very telling against the idea of recovery at incipient and no spins as not even the instructors are up to it or properly trained as pilots??

pace
Instructors who do not posses current Instrument ratings should not take their students flying in IMC conditions for the same reason that instructors who are not trained and proficienct in aerobatics should not perform aerobatic manoevers with their student, they are not qualified. A developed spin is an aerobatic manoever.

The entry into a spin is not an aerobatic manoever and recognizing and recovering from that entry in order to avoid the aircraft actually entering spin induced auto rotation is IMO what should be taught in the PPL, the subject of this thread.

As I said earlier the place to learn how to enter and recover from a spin is in an introductory aerobatics course where in addition to spinning you will learn a lot more about how to control an aircraft, regardless of what it happens to be doing, taught by someone who knows and can properly demonstrate this type of flying......and you will have an awfull lot of fun to boot

Last edited by Big Pistons Forever; 20th May 2012 at 21:25.
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Old 21st May 2012, 07:25
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I think that PPL training should look at the risks v exposure, and then try and mitigate these risks through training.

I don't think I recall a single accident where someone inadvertently entered a spin when at cruise height and failed to recover, other than during aerobatics and deliberately mishandling the aeroplane...Anyone else know of any accidents like this?

The stall / Spin accidents that I do recall have all been close to the ground and not recoverable and in fact the only way these accidents could have been avoided is not to stall in the first place.

So I don't think there is much merit in spin training as part of the PPL at all. I'd say that for an FI it is vital to learn, as I know of FI's who have been put into spins during a botched stall.

It was only when I did my CPL (FAA) that we really explored the envelope, and did all different types of stall (accelerated / turning / etc..), extreme unusual attitudes, stalls under the hood, as well as advanced stuff like chandelles and lazy-8's. Very worthwhile, but not necessary for PPL training....which after all is a licence to learn.
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Old 21st May 2012, 08:12
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Thank you for your reply Foxmoth. Most of my landings (and takeoffs, to be sure) in power have been in my trusty Supercub, used for towing gliders, and your experience of buffet as the precursor of incipient stall is something my darling GOFER never never displayed, because no matter how slowly we flew, it didn't seem to depart from controlled flight!

Perhaps the point I was trying to make applies more to gliders, particularly the training glider K13. This, as I mentioned, is the most widely used in British gliding clubs, for spin demonstration and practice.

We teach fully heldoff landings. This implies that rounding out (in the US, this is called the flare) a few inches above the turf, the wings will loose their lift as the angle of attack is increased slowly moving the stick back in level flight, untill the contact with ground takes place. The stick could now be moved back all the way, and the glider WILL NOT TAKE OFF AGAIN! as it is fully stalled. If the glider were not fully stalled, it may well leap into the air again, which is called a balloon, and there is nothing more embarassing or hard on the tailbone, than to drop in vertically from a ten foot altitude.

This is why it certainly appears that a well held off landing will touch down in a stalled condition. In flight at altitude, if you move the stick back all the way, and the elevator does not react in the usual sense of raising the nose, this is the only absolute symptom of the stall. Prestall buffet, sloppy controls, ASI, everything else is a precursor; the elevator not responding is a definite indication that the glider is stalled. Of course the cure is to move the stick gently forward, and the aircraft will nose down and air begin to flow over the wings again, lift restored.

I think it is comforting for beginners to be told a stall is no big deal, you've already seen a few, and in landing a K13, at least, it should be fully stalled as it touches down.
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Old 21st May 2012, 09:02
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I don't think I recall a single accident where someone inadvertently entered a spin when at cruise height and failed to recover
What is cruise height exactly? If you mean higher than in a circuit there must be some accidents like this or there would have been no argument to remove spinning from the syllabus in the first place. Unless we assume that all spinning accidents from altitude were intentional spins.

other than during aerobatics and deliberately mishandling the aeroplane
That's quite a bold statement. To me deliberate mishandling would only cover over-speed and over-stress or other out of envelope stuff which doesn't really apply to spinning. Lack of understanding can kill regardless of height if you are intentionally spinning... and there are always going to be those times that the aircraft does something strange and no one can explain why!

As far as what should be included in the PPL spinning is probably best left out because a student could have a 250 hour instructor that isn't competent to teach it! Even a demonstration might be a bad idea. That really sums it all up doesn't it?

Last edited by The500man; 21st May 2012 at 09:19.
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Old 21st May 2012, 09:36
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Mary,

Thank you for your lesson on landing, as an instructor of over 30years with probably 1500+ hours on taildraggers I had not heard this before

I used to believe as you have said about fully stalled landings, but had a VERY experienced instructor convince me otherwise. Yes, a good landing should be approaching the stall, but if you are actually stalled then the margin for error would be such that there would probably be more heavy landings than there are. My understanding of it is that the speed is decaying so rapidly at this point that by the time you bring the stick back you will be below the stall speed, plus, moving the stick back does not actually raise the nose - it lowers the tail, and if the tail is on the ground anyway it cannot go down any further (though of course if you bounce it is no longer on the ground so CAN go down more). Personally I think the question of a taildragger being fully stalled on landing is still up for debate, but at present the arguments I have heard against it have me on the "not stalled" side of the fence.

(n.b. Some Taildraggers are definitely NOT stalled on touchdown unless you have got it wrong and I think you will find the Supercub comes into this class, I seem to remember landing one of these slightly tailwheel first a couple of times so three point attitude is certainly lower than the stalled attitude.)

Last edited by foxmoth; 21st May 2012 at 09:59.
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Old 21st May 2012, 09:48
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Originally Posted by Prop swinger
. . . and yet it is perfectly safe to sideslip until just before touchdown. Isn't it routine for unflapped aerobatic aircraft (with no washout!) to sideslip to land?

If you maintain a normal airspeed & AoA it is perfectly safe to fly a slipping turn into a slipped final approach.
I had an instructor who showed me how to do exactly this in a PA38 from a very high approach. IIRC the trick was to nail 70kt on final with full flap, then apply full left rudder & use the ailerons to maintain directional control, regaining balanced flight just before the flare. I was never completely comfortable with the procedure as I always had a nagging concern about how it would affect the ASI. My CFI at the time wasn't that enthusiastic either & suggested it would be safer just to stuff the nose down & ignore the flap limiting speed if you ever had to make a landing area in a real emergency situation.
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Old 21st May 2012, 09:55
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If you had been taught to fly by attitude it wouldn't matter what your ASI was reading because if you were holding the correct attitude you wouldn't stall.

PA38 is quite good for side slipping. Just have to watch that you don't jump into a PA28 and expect the same results because you will be disappointed.
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Old 21st May 2012, 10:08
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Originally Posted by mad_jock
PA38 is quite good for side slipping. Just have to watch that you don't jump into a PA28 and expect the same results because you will be disappointed.
In most of the ancient PA28's I've flown, I could get a pretty impressive ROD just by removing the power.

But to keep this on topic, if you're sending someone off to practice slipping at a safe height, would you not also want to know that they could recover from an unintentional spin? A PA38, if stalled with crossed controls, won't give much warning before it bites & although I've never spun one with the flaps down, I'd expect you'd need to get them retracted smartish to avoid overstressing in the recovery.

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Old 21st May 2012, 10:26
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But to keep this on topic, if you're sending someone off to practice asymmetric flight at a safe height, would you not also want to know that they could recover from an unintentional spin? A PA38, if stalled with crossed contols, won't give much warning before it bites & although I've never spun one with the flaps down, I'd expect you'd need to get them retracted smartish to avoid overstressing in the recovery.
Sounds like you are getting mixed up here - Asymmetric flight is flying a twin on one engine, not flying crossed controls!
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