View Full Version : Wing dropping stall recovery.


AdamFrisch
13th May 2011, 10:48
How do you recover your stalls in less behaved aircraft that tend to drop a wing (assuming it it's not spinning yet, of course)?

With rudder only or elevator and then aileron once out of stall?



mad_jock
13th May 2011, 11:02
Use rudder to halt any further wing drop while decreasing the angle of attack. This isn't a 2 phase action it is done at the same time.

Then roll wings level again once the aircraft isn't stalled any more using aileon.

Its well worth getting hold a a gliding flying manual they seem to have this stuff way better explained. To be honest from the glider pilots I have seen its taught alot better in gliding courses than most powered pilots get.

BackPacker
13th May 2011, 11:57
Yep. You use rudder and elevator because those are the only two flying surfaces that are almost certainly not stalled.

You don't use ailerons to correct the wing dip during the stall because your wings are stalled. Using the ailerons may worsen the situation. Although "modern" designs are so that the inboard portion of the wings stall first, and the outboard section last. So to an extent, in those designs, ailerons will remain active up to and into the stall.

You do use ailerons after you've broken the stall though. First roll to the nearest horizon, then pitch up to recover from the dive.

Don't pull up and roll at the same time though. This leads to the "wing root bending" effect, where the wing root on the upgoing wing is stressed because of both the pitch up and the rolling moment. In extreme cases this may lead to excess g stresses which don't register on a g meter or elsewhere, and thus hidden defects.

Probably not relevant when you do a proper recovery from a simple 1G/S&L stall in a well-behaved aircraft, but good training for aerobatics and/or stall recovery in nasty types.

BEagle
13th May 2011, 13:54
Keep the aircraft in balance with rudder - don't be tempted to 'pick up the wing' or 'stop any wing drop'. That teaching went out years ago (except perhaps where dinosaurs still roam..).

Full power and control column centrally forward until the stall ident stops.

Then and only then, roll wings level and recover from the descent.

Tinstaafl
13th May 2011, 15:08
I'm with Beagle. Rudder isn't there to provide roll control. It's a *yaw* control - so use it for that.

After recovering from the stall - in whatever angle of bank that might be - and the aircraft is flying again, then use conventional coordinated aileron & rudder to roll to the nearest horizon. Once wings level, pitch to recover to S&L or climbing flight. If power is available then select full power once the angle of attack has been reduced during the stall recovery actions.

Dan Winterland
13th May 2011, 15:24
Wot BEagle said.

AdamFrisch
13th May 2011, 16:19
Beagle, Tinstaa, SoCal - being contrarian devil's advocate: To that I would argue that a wing drop is a more stalled wing than the other and therefore you're into the onsets of a spin, therefore spin recovery techniques are in place. Which means rudder.

Genghis the Engineer
13th May 2011, 16:19
I'm also with BEagle, there is no immediate benefit to picking up the wing.

Unstall it with pitch and power (CAA would say together, FAA would say pitch first, both works, CAA loses a bit less height, take your pick), once it's flying again, roll wings level and climb.

Leave the rudder and ailerons firmly still until the aeroplane is unstalled and flying again.

G

Genghis the Engineer
13th May 2011, 16:24
Beagle, Tinstaa, SoCal - being contrarian devil's advocate: To that I would argue that a wing drop is a more stalled wing than the other and therefore you're into the onsets of a spin, therefore spin recovery techniques are in place. Which means rudder.

Central ailerons and stick forward will recover from incipient spin - and until a spin is established, how do you know which way it's spinning, or that rudder won't CAUSE a spin? You don't.

G

AdamFrisch
13th May 2011, 16:33
The aircraft will spin in the same direction as the wing that drops first.

Lister Noble
13th May 2011, 16:51
I think my natural reaction would be to push the stick forward,because my hand is already on it,then power,all 65 hp of it;)

AdamFrisch
13th May 2011, 16:53
The reason I asked is because I've been taught both by different instructors at different times. My inclination would be to push forward and do a normal stall recovery, but there might be some traction to the rudder variant.

Genghis the Engineer
13th May 2011, 16:57
The aircraft will spin in the same direction as the wing that drops first.

Not necessarily, particularly if you are stupid enough to apply opposite rudder whilst the aeroplane is still deciding whether to spin or not.

G

Conventional Gear
13th May 2011, 17:31
I'm not sure I'm following this.

When I did accelerated stalls in the Warrior if the wing dropped and it could be vicious, the drop was stopped with opposite rudder, yawing the plane if you like away from the dropped wing arresting any further wing drop.

Recovery was then as described. Stick forward, power on level the wings with aileron when they were 'un-stalled'

Surely if you do nothing with the rudder when you have a rapidly dropping wing there is the risk of entering a semi-stalled spiral dive in which case normal stall recovery is not what is required, power off, level wings, recover from the dive. Hence I was taught to catch the wing drop with rudder. The only really 'dumb' thing you could do was to give rudder in the same sense as the wing drop, i.e. a classic spin entry.

Not saying it is right or wrong, just trying to figure out why not to use rudder to catch a dropping wing when it is all you have left. As discussed aileron is of no use so if the wing is rapidly falling away how do you arrest it without rudder?

I can see an argument for keeping the aircraft in balance for the stall, then it won't drop a wing, hmmmmm is that the point of the exercise? I thought a dangerous stall was one you didn't expect not the one you planned. :confused:

Lord Spandex Masher
13th May 2011, 17:52
Well if you recover correctly and quickly you won't end up in a "semi-stalled spiral dive". Whatever that is.

A question. How is a conventional spin initiated?

Conventional Gear
13th May 2011, 18:04
A question. How is a conventional spin initiated?


Depends on type, but generally, power off, stick full back, full rudder into the direction of the spin, perhaps opposite sense aileron for some types.

My question is how are you suppose to recover correctly if you have 90 degree bank due to a dropped wing that was not checked? As you can't pick up the wing with aileron, a rapid yaw in the opposite sense of the drop will accelerate the wing **enough** to arrest the drop. The point being recovery is not about 'properly' executed stalls, it should be instinctive in messy ones too.


http://www.helitavia.com/docs/CAP562_CAIPS_11_airworthy_info.pdf

Link explaining semi-stalled spiral dive condition.

Lord Spandex Masher
13th May 2011, 18:13
Depends on type, but generally, power off, stick full back, full rudder into the direction of the spin

So you want to do that to pick up a wing?!

Don't forget that while you are accelerating one wing you'll be decelerating the other. Maybe enough to induce a stall and, therefore, spin in the opposite direction to your wing drop.

how are you suppose to recover correctly if you have 90 degree bank due to a dropped wing

The same way you recover from 1 degree of bank, or 20, or 45 etc. Unstall the wing and apply power then ailerons to return to wings level.

Conventional Gear
13th May 2011, 18:27
Don't forget that while you are accelerating one wing you'll be decelerating the other. Maybe enough to induce a stall and, therefore, spin in the opposite direction to your wing drop.


Yep I see the argument now.

The fact is though I've seen the rapid yaw to catch the wing demonstrated and have used it. We never entered a spin in the opposite direction. It's all one smooth movement, catch the drop nose down, power on and recover.

Remember too I was talking about accelerated stalls or if you like power on stalls, when very likely it is the outer wing sections that are stalled first (no airflow from the prop) and wing drop can be very sudden. I can't imagine how one would simply put the nose the down and level the wings from that flight condition in a Warrior if the wing drop wasn't first caught by rudder, the thing would be in an extremely uncomfortable attitude by that time and likely the story would be over.

Lord Spandex Masher
13th May 2011, 18:35
Don't think of it as lowering the nose - although that is what you do if you're straight and levelish - it's more a case of reducing your angle of attack. You can do that at 90, 180 or even 270;) degrees of bank.

If you try hard enough in the Warrior I'm sure you could get an accelerated stall inverted (I don't recommend it though). What are your actions going to be then?

Conventional Gear
13th May 2011, 18:44
If you try hard enough in the Warrior I'm sure you could get an accelerated stall inverted (I don't recommend it though). What are your actions going to be then?


eeeer.... pull back? :\

Can't wait to do some aeros and find out more. :ok:


Sorry I had to edit that as inverted mode didn't work out in my head

BackPacker
13th May 2011, 19:11
I can see an argument for keeping the aircraft in balance for the stall, then it won't drop a wing,

Not necessarily true. If the aircraft has a lateral imbalance in weight (e.g. a side-by-side seater with just one POB, or due to a fuel imbalance) and you fly the aircraft level and in balance, one wing will be lifting slightly more weight than the other. You counter this with a tiny bit of aileron, but that will minutely change the average angle of incidence and thus the stall AoA.

Furthermore, due to inaccuracies when building, previously encountered damage, wings that may have been taken off for transport or maintenance, different amounts of dirt on the wing and various other "rigging" issues, the actual angle of incidence, washout, twist or other aerodynamic factors, may be slightly different between the left and right wing. This may also cause one wing to stall slightly earlier than the other, leading to a wing drop.

Of course how severe these issues are will depend on the actual airframe. Both the design of the airframe (high-wing vs. low wing for instance) and the actual rigging.

But I would not assume that an aircraft that's flown in balance will not drop a wing in a stall.

AdamFrisch
13th May 2011, 21:28
I actually just checked out the price of an Angle Of Attack meter and guess what - it's $565. That's nothing. A very useful instrument. Think I might get one and install it at some point.

flybymike
14th May 2011, 00:27
This is a perennial subject, which always brings up the same arguments, and drives me nuts.

Wot Mad Jock says.

Pick the Goddam wing up with the rudder and move the stick forward simultaneously then use aileron to level wings when unstalled.

If you don't like the phrase "picking up the wing with rudder" then call it "stopping further yaw with rudder" "preventing further drop with rudder" "keeping the aircraft in balance with rudder." Whatever; Dress it up any which way you like, but use rudder and elevator first 'cos IT WORKS!

Whopity
14th May 2011, 07:36
SSR: Control column centrally forward; simultaneously apply full power; maintain balance (prevent further yaw) with rudder.

If you apply rudder at the point of stall: HOW MUCH? What are you looking for?

Moving the CC forward you are looking for the signs of the stall to cease

Then you can roll the wings level with aileron.

Cows getting bigger
14th May 2011, 09:01
I'm sure that most of us can do two or three things at once :). The priority in any stall must be to 'unstall' the wings and that is only done by reducing AOA - centrally forward on the controls. Now, if we have the capacity to do the other couple of things, a bit if opposite rudder (to arrest wing drop) and application of power will minimise the altitude loss. Of course, we all know what the secondary/adverse affects of such actions are and how to counter these. :eek:

Personally, I find this a non-discussion for most simple aircraft types. The process should be automatic and we shouldn't be thinking about the order of control inputs during the stall.

BEagle
14th May 2011, 09:40
Whilst 'full power and control column centrally forward, keeping the aircraft in balance with rudder' is totally correct, many instructors fail to teach how far forward the CC should be moved. The answer is no further forward than the attitude at which the stall ident ceases, then maintain that pitch attitude to accelerate, roll wings level with aileron and recover from the descent.

On Skill Tests I'd often get applicants applying full power and stuffing the nose earthwards excessively at the first squeak of the stall warner.

One pet hate I have is the use of 'signs' and 'symptoms' of the stall - which came from teaching medical students who told me that the RAF's use of the terms was incorrect. So I use 'stall warning' and 'stall ident' - the same terms as you will see on many large aircraft stall protection systems.

Conventional Gear
14th May 2011, 12:29
One pet hate I have is the use of 'signs' and 'symptoms' of the stall - which came from teaching medical students who told me that the RAF's use of the terms was incorrect. So I use 'stall warning' and 'stall ident' - the same terms as you will see on many large aircraft stall protection systems.


I would have considered 'symptoms' and 'signs' to relate to things such as mushy controls and buffet and would have thought the words descriptive enough? i.e. things that occur in many light aircraft before a fully developed stall, not built in warning systems, simply observable effects?

mad_jock
14th May 2011, 15:19
I don't agree with picking it up, just apply enough that the wing stops dropping while reducing AoA.

flybymike
14th May 2011, 16:14
Yes, As I suggested, I was using the "picking it up" term colloquially, and other descriptions may be more literally accurate. I agree that no more than necessary to prevent further drop is correct. I usually find that a rapid, preferably instant response with a "stab" on the opposite pedal is all that is required

Gertrude the Wombat
14th May 2011, 18:45
we shouldn't be thinking about the order of control inputs during the stall
It's not completely unknown to do everything at once in an unusual attitude recovery and be told by the instructor or examiner that we've confused them by not demonstrating that we know the correct order in which to do them one at a time.

Conventional Gear
14th May 2011, 22:16
Quote:
we shouldn't be thinking about the order of control inputs during the stall
It's not completely unknown to do everything at once in an unusual attitude recovery and be told by the instructor or examiner that we've confused them by not demonstrating that we know the correct order in which to do them one at a time.

Yep I remember well being drilled to perform the movements in an exaggerated way in the correct order to satisfy the examiner.

I then got moaned at for not recovering into a climb. Total height loss, 50ft :(

I felt like a should have just pointed the nose down, lost 300ft and made everyone happy. Flying is a weird world at times.

flybymike
14th May 2011, 22:33
Especially when you are upside down..

mad_jock
14th May 2011, 23:02
I do wonder if it would be better to teach let go of everything say 1000 and then fly straight and level would be the best way for most PPL's to deal with stalling.

moreflaps
14th May 2011, 23:16
Hi Jock

Letting go of everything could be a very bad idea in a wing drop stall -which could lead to an incipient spin IMHO. I believe NASA tests showed the Mueller/Begs technique is less reliable than PARE... although M/B still needs you to know what rudder to press and hold (the hard one). Of course the POH is key knowledge here.

From Wikipedia: "The mnemonic "PARE" simply reinforces the tried-and-true NASA standard spin recovery actions—the very same actions first prescribed by NACA in 1936, verified by NASA during an intensive, decade-long spin test program overlapping the 1970s and '80's, and repeatedly recommended by the FAA and implemented by the majority of test pilots during certification spin-testing of light airplanes."

Cheers

Mark1234
14th May 2011, 23:59
Not really moreflaps. In a spin the yaw comes from one wing being further back up the drag curve (more deeply stalled) than the other. If everything is flying, that doesn't happen.

It really is that simple: In order for bad stuff to happen, you must be stalled. Remove the back stick (e.g. let go), you're not stalled anymore - Quickly and promptly remove the AOA, then sort it all out. You might guess I don't particularly hold with the idea of powering out of a stall either :suspect:

A wing drop does not require a spin recovery. Personally I'd be looking for something like 180+ of heading change before even thinking about spin recoveries. Being cautious of spins is good, but I do wonder if most folks consider anything beyond 30deg bank to be an incipient spin (a term I hate.. you're spinning or you're not!)

mad_jock
15th May 2011, 00:02
I stated PPL's not some aero savy pilot.

The best way to stop Joe blogs stalling is by teaching correctly exercise 1-13 with full reference to attitude flying. ie they know what attitudes to select and the ones not select. And also to recover from the incepent stall not a fully developed stall.

We are talking PA28's C150's, C172's and your general run of the mill spam can's most of which will recover from a spin by letting go of everything. If you let go even in a PA38 it won't spin even with a 80deg wing drop.

As much as these discussions like us to believe the pilot has to seriously screw up major time ignoring multiple indications either stall warners or extreme attitudes before they are anywhere near a stalling condition.

yes I can complete agree with you if you are inverted with 60 deg nose up letting go of everything might not be the best plan.

If you are Joe Bloggs Numbnuts going for a 300 quid burger and you are trying to get a photo of your mates house at 3000ft and you haul back to much while looking out the side window, letting go will solve your problem.

More attention to the basics of flying and attitudes as a discussion would do more for flight safety than endless discussions about how to dick around in a stalled condition.

prevention is better than cure

moreflaps
15th May 2011, 10:54
Hi Mark, re: "Not really moreflaps. In a spin the yaw comes from one wing being further back up the drag curve (more deeply stalled) than the other. If everything is flying, that doesn't happen.

It really is that simple: In order for bad stuff to happen, you must be stalled. Remove the back stick (e.g. let go), you're not stalled anymore - Quickly and promptly remove the AOA, then sort it all out. You might guess I don't particularly hold with the idea of powering out of a stall either "

I partially agree with you but would add that the spin results from the roll-yaw couple that is always present. If you have aft COG letting go of the controls may not reduce the AOA enough due to presence of gyroscopic precession (due to both yaw and prop). Reducing yaw with rudder reduces the gyroscopic effect and that may allow the nose to drop when the stick is moved toward the ground. As for powering out of a stall, one would hope that right rudder is used to stop the yaw that appears as the engine powers up... I agree that power is not necessary in stall recovery (except to reduce height loss).

Cheers

Crash one
15th May 2011, 22:14
one would hope that right rudder is used to stop the yaw that appears as the engine powers up... I agree that power is not necessary in stall recovery (except to reduce height loss).



Wouldn't that depend on who built the engine? ref: rotation direction.

Pilot DAR
16th May 2011, 02:06
Reducing yaw with rudder reduces the gyroscopic effect and that may allow the nose to drop

Yes, I agree with this. This is the theme of spin explanation in an excellent book on flight test I've been reading. If you sketch out an aircraft spinning down, considering the mass of the engine in front, and the rest of the aircraft mass, which is location variable (as C of G), the further aft that mass is in the fuselage, the more it responds to centrifical force, and flattens the spin.

It also bears out well my recent experience spin testing the modified Grand Caravan. It was a very different recovery aft C of G than forward, I expect for exactly this reason.

AdamFrisch
16th May 2011, 02:13
Aft CG in a spin can be very dangerous. There's the story of the spin where finally the pilot got out of it by leaning forward as much as he could just in time to save it. It's also a case for securing your loads and be vigilant about your weight and balances.

Pilot DAR
16th May 2011, 02:33
As unpleasant as this video is to watch, it is a very useful example of a spin entered and apparently no effert made to recover it. Left rudder was applied, and the predicable left yaw, then wing drop can be seen. Tiger Moths, more so than most types will slow down very quickly once behind the power curve. Add to that, the drag rise of the stall occurring, and also add an occupant with the maximum possible drag creating position on the aircraft, and the Gypsy Major just did not have what it took to get out

Apparently, no effort was made to recover, as left rudder input is never removed.

YouTube - Tragic Airplane Accident - Tigermoth Loses Power on T.O.