Skidding turn stall

[201er]

Just curious, anyone stalled a Mooney in a skidding turn? What's it like? How many knots sooner does stall occur at in the skidding turn than straight ahead?

http://mooneyspace.com/topic/19671-steep-turn-base-to-final/?do=findComment&comment=294968

Good video recently shared on the subject makes me curious what it's like in a Mooney. All my experience with stalls always put emphasis on being coordinated during the stall so I don't recall experiencing a more than slightly skidded stall.

 

[N9201A]

Skidding is cross-controlling. Cross-control stall=spin entry.

Have you read this? May answer your question.

http://www.mooneyevents.com/spins2.html

[Yetti]

my butt makes me fly coordinated.  Stalls practiced above 5000 feet

 

[kortopates]

Not exactly true that all cross controlled stalls will result in a spin.

For example, there is huge difference between a stalling in a skidding turn versus in a slipping turn; especially at near idle power.

But no, I have no intention of stalling a Mooney in a skidding turn!!

Sent from my iPhone using Tapatalk

[jetdriven]

I think that's the thing, don't skid or skip the turns, and above all that, don't stall it unintentionally. 

[N9201A]

Yes Paul of course you're right. hamfisted ones!

As I recall the CFI PTS had this as a demo maneuver (at least we trained for it) and a Cherokee will just hobbyhorse along, with no vices. Not our Mooneys!!

[201er]

32 minutes ago, jetdriven said:

I think that's the thing, don't skid or skip the turns, and above all that, don't stall it unintentionally. 

Totally agreed. But surely some Mooney instructor has had the displeasure of having watched a student cause one? I'd like to hear any first account of the survivors of how the entry is different than a normal stall. Not the horror stories of what happens, but how many knots faster than normal stall, alternative warning signs, etc.

[Vance Harral]

After a lot of thought and consultation with the person giving the training - including discussing Don Kaye's negative experience with uncoordinated stalls linked to above - I chose to take the calculated risk of executing slipping and skidding stalls in our M20F during my CFI training.  I've only done this a few times, always at 5000+' AGL.

The setup was based on what an inexperienced student might do in a base-to-final turn.  In the slipping case, the scenario was that you're already slipping to lose altitude, you overshoot the runway centerline, and get too aggressive with a steep turn in an attempt to get aligned.  In the skidding scenario, the concept was a student who executes a shallow turn due to fear of bank angle, uses rudder to horse the nose around to the centerline, and pulls back on the yoke to counter the resulting nose-down behavior.

I wouldn't call these cross-controlled stalls "benign", but with prompt execution of appropriate recovery techniques I don't think they're dangerous, per se.  In a slipping turn, the stall rolls the aircraft to the outside of the turn, i.e. toward wings level.  As you might guess, that's not particularly scary.  A skidding turn is more of an E-ticket ride, as the stall rolls the aircraft to the inside of the turn, i.e. away from wings level.  On executing the first one, it felt like the airplane rolled nearly knife edge.  But the instructor demonstrated that was nowhere near the case.  On executing a second one and really paying attention, I found the wings did not exceed 60 degrees of bank.  What's surprising is not the total bank angle, but rather the speed at which it rolls to that bank angle.  A skidding stall is, by definition, the entry portion of a snap roll.

I didn't pay much attention to the airspeed indicator during these maneuvers.  Stall speed was higher than the bottom of the white arc, of course, but I don't remember it being way around the dial.  Let's say it was closer to 70 MIAS than 100 MIAS.  But I'm not sure it's an interesting number anyway.  The pitot/static system has some degree of error in slipping/skidding turns, and we know it's AOA rather than airspeed that matters anyway.

Recovery is no different from coordinated stalls: immediately reduce the angle of attack with forward pitch, use the rudder (not the ailerons) to level the wings, then execute an appropriate return to climbing flight.  I was primed for an immediate recovery since the maneuver was intentional, and that's contrary to the way it would go down in real life.  But with a nod to Don's experience, neither the instructor or I had any desire to "really get into it".  Unlike counting to three when you pull the power on a simulated engine failure, we didn't attempt to model the disbelief delay in recovery.  Even so, the altitude loss in the skidding case is several hundred feet, i.e. probably more than the margin you have on a base-to-final turn (that demonstration being one of the main points of the maneuver).

I'm not advocating anyone else do this, and respect those who may argue it's not a good risk/reward tradeoff.  But cross-controlled stalls are part of the CFI curriculum, and I didn't want to do them in an aerobatic airplane with different characteristics than the aircraft I mostly teach in (we did use a Citabria for the spin training).  If you choose to explore these maneuvers, recommend you do it with an aerobatics-capable instructor with 1000+ hours in your specific make and model of Mooney, like I did.  Also, be aware of potential differences in the different Mooney airframes.  In particular, our mid-body model with the full-span rudder in the back and "only" the IO-360 motor up front has as much or more rudder leverage as any other Mooney model.

[takair]

 

Like Vance, one of my more memorable stalls in the Mooney was related to my CFI check ride.  Upon reviewing the maneuver list, the examiner chose the secondary stall as my "stall maneuver".  This consists of demonstrating a basic stall and then simulating a "panicked" (my interpretation) student who pulls aggressively into a secondary stall.  This is basically no more than an accelerated stall (AOA exceeded, even though speed may be above stall speed).  I can tell you from the checkride, that the accelerated stall is far more critical in slip or skid ( ball not centered) than the standard stall.  It is fair to say that the wing drops more rapidly, enough to make the examiner nervous.  Recovery is typical stall/ spin recovery.  Rapid push and then recover the wing with the rudder.  I find that getting people and myself to keep ailerons neutral is the hardest thing.  Ailerons in the stalled condition exasperate the stall and can themselves contribute to spin.  I did not contribute to the previous steep turn thread, but I don't think an unloaded steep turn is hazardous in itself, it is the loaded and accelerated stall, compounded by any slip or skid that can lead to the spin.  I think you said as much by describing AOA.  It is all about comfort zone, steep turns are ok if folks understand what happens when you exceed the limits, as you know, we would not want to find that out down low on our first attempt at any of these maneuvers.  In the case you describe above, it is not simply the speed, but the amount you load the wing....back to your AOA argument.  Keep the speed up, and AOA low and even the skid or the slip doesn't cause a stall....as we see in your video.  Some of the posts have mentioned that the AOA only reads one wing.  I believe that the scenario you pose is where dual AOA may come into play.  The skid or slip is accelerating or  slowing one wing. If you then load up the slow wing a little more, it exceeds the  critical AOA and you have a spin.  That said, I don't think you would be able to read that difference on a dual AOA fast enough to respond, which is why we fly with some margin built in.  When flying airspeed we need more margin, when flying AOA indicator we may fly closer to the margin, if we had dual AOA (one for each wing), a computer might be able to take use even closer to that margin, seat of the pants margin is individual ability, proficiency and experience.  Even in the test pilot ranks, the ability to recognize and recover varies, which is why even the OEMs have test pilot's of different backgrounds and abilities.  I know this does not directly answer the question, but perhaps contributes a little...

[201er]

Two very very interesting and informative responses. Thank you!

Still leaves me with the question of just how much of a roll (no pun intended) the cross control plays on the stall entry. How much sooner does the plane stall than in a comparable coordinated turn? A half second sooner, 5 miles an hour earlier? Or is it more substantial than that. Obviously each plane is different so Mooney specific is the question. I would think the longer wings of the Mooney would make it more significant.

From the video of the guy talking about skidding stalls, it sounds like a really big deal. In my experience it would seem like it would only act as a catalyst in an already borderline stall condition at already high angle of attack.

I would imagine the ASI to be more impacted than stall earning or AOAi because the pitot tube is further out on the wing than the stall vane. Is the difference in measured vs actual airspeed even measurable between a right hand and a lfeft hand turn?

[takair]

28 minutes ago, 201er said:

Two very very interesting and informative responses. Thank you!

Still leaves me with the question of just how much of a roll (no pun intended) the cross control plays on the stall entry. How much sooner does the plane stall than in a comparable coordinated turn? A half second sooner, 5 miles an hour earlier? Or is it more substantial than that. Obviously each plane is different so Mooney specific is the question. I would think the longer wings of the Mooney would make it more significant.

From the video of the guy talking about skidding stalls, it sounds like a really big deal. In my experience it would seem like it would only act as a catalyst in an already borderline stall condition at already high angle of attack.

I would imagine the ASI to be more impacted than stall earning or AOAi because the pitot tube is further out on the wing than the stall vane. Is the difference in measured vs actual airspeed even measurable between a right hand and a lfeft hand turn?

I am curious of the speed difference myself.  My feeling is that you have to be at the ragged edge, basically right below stall AOA and then a couple of knots is all it may take to get the inside wing to stall.  Once the rotation starts, the outside wing is developing more lift and is certainly faster.  I suppose we could calculate it, somewhat easily, but we would need to figure out the diameter of a spin.  Also, the ailerons play into this a lot.  They change the local AOA, so you may have margin in speed, but when you crank in the aileron, the local AOA between wing tips changes rapidly.  So, I think the question has a lot of variables.  Your question is a fair one, but may not have a single answer.  Perhaps what we are both looking for is how much margin we need to carry in our airspeed or even AOA indication so that reasonable aileron or rudder deflection do not trip a single wing stall (ie spin entry).  My guess is that the actual speed is small, but the consequence is big.  For example, when doing spins (not in a Mooney), you can be doing slow flight on the stall horn and kick rudder and get a spin (some aircraft are easier than others).  Similarly, you can throw in aileron and get the opposite results (wing drop opposite to aileron intention).  You may actually notice it more in the Mooney. Doing straight stalls (ball centered), it seems to me that the stall break is marginally slower ball centered than if the ball is off a little.  That said, I can't read the difference on my airspeed.  I would be nervous to do this same entry with much more than a little rudder or ball out of center, but I suspect that again we would not be able to read it without an instrumented plane.  I know that I am comfortable doing forward slips with full rudder and a lot of aileron, but I am far from my stall margin.  I don't yet have AOA, so I don't know what that looks like, but I am far from the buffet.  Of course, the aerobatic guys can get a nice snap roll at quite a high airspeed by aggravating all of the controls at once.

[201er]

I suppose it is the combination of being pretty high angle of attack (slow), over banking, loading the wing (pull back), and skidding that coupled together cause a stall at an airspeed that would otherwise seem to be stall-safe. The crazy thing is that the pitch attitude may not be high at all and possibly even below the horizon. This is why I find flying by airspeed and more particularly strictly following a single set of airspeed numbers in all situations to be dangerous.

The way stalls are taught is quite lacking. Straight ahead power off, straight ahead power on, and maybe with an ambitious instructor a ten degree coordinated turning stall at half loaded weight. This is NOT what most of the stalls people perish in look like. As far as I can tell, the only lesson keeping most beginner pilots from stalling is to blindly keep the speed up pretty high in the pattern, don't bank steep, and caution in the side of excess speed. This is not a genuine awareness of the airplane's angle of attack.

[Vance Harral]

Concur this isn't a one-axis problem.  I'm sure there's some variation in indicated stall airspeed during a stable, constant rate coordinated turn vs. a stable, constant rate skidding (or slipping) turn.  But as the linked video discusses, the event that causes the stall may be the movement of rudder or aileron controls at a critical moment, rather than increasing pitch input and/or reducing airspeed.  The effective change in AOA caused by the rudder and/or aileron input triggers the stall in these cases.

The most obvious demonstration of this to me was my spin training.  We performed spin entry in the Citabria by slowing to MCA, then simply pressing one rudder pedal all the way to the floor to trigger the stall and resultant spin, with no additional backstick.  In other words, the stall/spin was initiated entirely with yaw input, not pitch input.  It generated a nice, crisp entry that I'm sure looks good in competition aerobatics, and was certainly sufficient for learning spin recovery.  But I'm not sure it was a good demonstration of the inadvertent spin entry we worry about as instructors.  Sure was fun, though!

Anyway... this discussion of how much "sooner" a stall occurs in a skidding turn isn't meaningful, IMO.  It seems to assume you're in stable skidding turn, with a specific, constant amount of crossed aileron and rudder input, then you ease back on the yoke to the break.  You can run that experiment, and in fact that's the way my instructor had me perform cross-controlled stalls.  But I don't think that's how most stall/spin accidents happen, at least not in Mooneys.  In particular, the amount of elevator backpressure required to induce the stall under those conditions is enormous (I'd estimate 20+ lbs of force, and that's based on being trimmed for a stable 500 fpm descent).  You'd think would be a huge clue  you're about to cause something bad to happen.  On the other hand, if you start out in a coordinated turn, then kick in a bunch of ill-advised rudder and simultaneously apply opposite aileron and just a little bit (or no) of backpressure, I can see a surprise snap roll occurring.

Because of this, I'm not enamored of using a steep turn to final to bleed off energy.  I understand the aerodynamic argument, and believe it's technically "correct", especially with respect to a descending turn at relatively lower load factor.  But much like inducing an accelerated stall from rapid pitch input, one can induce a stall from rapid uncoordinated roll/yaw inputs over a wide range of indicated airspeed and G load (i.e. the fact that you're not "loading up the wing" doesn't necessarily protect you).  Not an issue if you "never" fly uncoordinated, of course.  But we all make mistakes, and those mistakes are more likely at steeper bank angles.  As a specific example from my own bag of experience, I've learned that a coordinated turn in the pattern with a healthy crosswind can give the appearance of a slip or skid, based on ground track.  I caught myself applying inappropriate rudder under those conditions once.  I was genuinely making an attempt to stay coordinated, but using the wrong reference (my eyes, instead of my butt and the slip/skid ball).  It was night time, which aggravated the visual illusion, but I make no excuses.  It was a mistake worth noting.

I agree with 201er's point that airspeed is an error-prone proxy for AOA.  But lest anyone get too enamored of AOA technology, note that an AOA indicator may very well let you down in a slip/skid scenario too.  There are a couple of different GA AOA sensor technologies, and I don't know which one 201er has.  But to my knowledge, none of of them are designed to account for sudden aileron or rudder input.  I'd wager any of the GA AOA devices would be "late" in going yellow/red during a spin initiated by rudder or aileron input.

[PTK]

17 hours ago, 201er said:

Just curious, anyone stalled a Mooney in a skidding turn? What's it like? How many knots sooner does stall occur at in the skidding turn than straight ahead?

I don't think this question can be answered. By definition a skidding stall may not give you any warning at all as does the straight ahead stall with the classic buffetting and left wing drop.

In a skidding stall the trailing wing stalls farther out towards the wingtip. The separated boundary layer airflow over the wing will not hit the elevator giving you the typical warning of a straight ahead stall. So without any of the classic warning the unsuspecting pilot may be expecting he/she continues to cross control away and the airplane will snap roll quickly. Do so in the pattern it's game over.

Here's some pretty pictures...

http://www.boldmethod.com/learn-to-fly/aerodynamics/slip-skid-stall/

[201er]

10 minutes ago, Vance Harral said:

Anyway... this discussion of how much "sooner" a stall occurs in a skidding turn isn't meaningful, IMO.  It seems to assume you're in stable skidding turn, with a specific, constant amount of crossed aileron and rudder input, then you ease back on the yoke to the break. 

 

Ok, let's talk about those rudder kick spins. That's interesting that the rudder alone took you from slow flight to stall. It makes sense cause as the wing turns to the relative wind, it produces less lift and increases AOA. Can you ballpark how many knots you were from a straight ahead stall when you stalled it with the rudder rather than elevator? I'm just trying to get a sense of how much impact the rudder can have.

As to your second point about a constant skidding turn. I wasn't talking about that either. I'm curious how many knots faster than stall would be slow enough that an addition of excess skidding rudder would cause the stall. How much speed worth is the skid. Or in reverse, how many knots over "stall speed" is there insufficient rudder to cause a skid stall.

10 minutes ago, Vance Harral said:

There are a couple of different GA AOA sensor technologies, and I don't know which one 201er has.  But to my knowledge, none of of them are designed to account for sudden aileron or rudder input.  I'd wager any of the GA AOA devices would be "late" in going yellow/red during a spin initiated by rudder or aileron input.

And as to this point, it may well happen quicker than any device would demonstrate. Agreed. I think the advantage of an AOA indicator is that you would already be referencing an AOA with a safer margin in the turn in the first place giving you adequate overhead. When referencing airspeed alone, unless you're very very fast, when combining factors (weight, bank, load), the pilot may well be flying with a lower margin than he expects. It's very enlightening to glance at my AOA during a loaded steep turn at or over 100 knots and see the AOA being quite high and stall margin quite low. An excessive pullback with a skid may be pretty close to sending it over the stall.

Edited September 9, 2016 by 201er

[jetdriven]

2 minutes ago, PTK said:

I don't think this question can be answered. By definition a skidding stall may not give you any warning at all as does the straight ahead stall with the classic buffetting and left wing drop.

In a skidding stall the trailing wing stalls farther out towards the wingtip. The separated boundary layer airflow over the wing will not hit the elevator giving you the typical warning of a straight ahead stall. So without any warning of the unsuspecting pilot will cross control away and the airplane will snap roll quickly. Do so in the pattern it's game over.

Got any evidence of the wing stalling towards the tip first? Sounds like conjecture to me. The whole wing stalls sooner, and yes there is Buffett. 

Edited September 9, 2016 by jetdriven

[PTK]

On September 9, 2016 at 5:03 PM, jetdriven said:

Got any evidence of the wing stalling towards the tip first? Sounds like conjecture to me. The whole wing stalls sooner, and yes there is Buffett. 

I don't think so! You may change your opinion on this if you review the aerodynamics of a skidding stall!   

A stall is when wing exceeds critical aoa. Different wing shapes behave differently. In swept wings the stall starts at the wingtip and moves inward towards the root. Stick shakers are used to provide feedback. In rectangular wings such as ours it starts at the root and moves out towards the wingtip.  

In a skidding stall with cross control yaw and elevator inputs the trailing wing starts to stall at the wingtip inward. It behaves like a swept wing because the airflow is not perpendicular to the wing. It meets the wing at a cocked or swept angle. It can snap roll inverted into a spin in a split second without any warning to the pilot. Hence the name "incipient spin."

Lesson: Do not skid the airplane in the pattern. It serves no good purpose.

 

[Vance Harral]

1 hour ago, 201er said:

Can you ballpark how many knots you were from a straight ahead stall when you stalled it with the rudder rather than elevator? I'm just trying to get a sense of how much impact the rudder can have.

Tough to ballpark, we didn't take data and the training was several years ago.  I can tell you I remember it wasn't necessary to get right up to the hairy edge of a straight ahead stall with buffeting, etc. before kicking rudder.  The instruction I got was to reduce power to idle, raise the nose smoothly to maintain altitude until hearing the stall warning (this particular Citabria was so equipped), then kick the rudder.  So the "margin" was at least as much as the difference between the stall warning and the actual stall speed.  Given the ease with which we entered spins, I suspect I could have initiated the spin with rudder-only input even several knots faster than stall warning speed.

It's helpful to do some guestimate math to get a feel for the numbers.  Based on my recollection and looking at some spin vidoes online, the yaw rate in a spin in the Citabria appears to be about 180 degrees per second.  It's probably fair to guess the yaw rate you can induce by stomping on the rudder is in the same ballpark as the spin rate, which suggests you can (temporarily) accelerate the wings about 180 degrees per second with a rudder stomp.  With a wingspan of 33.5', that means the wingtips have a relative differential velocity of about 53 feet per second when you kick full rudder, i.e. the outside wing is suddenly moving 53 fps faster than it was before, and the inside wing 53 fps slower, for a difference of about 100 fps.  100 fps is 68 mph.  That's a dramatic difference in velocity between the inside and outside wing tip at GA speeds, with a commensurate difference in lift.

Now, the yaw doesn't cause critical AOA to be exceeded by itself.  But the significant differential lift on the two wingtips induces a significant rolling moment, and the resulting drop on the inboard wing is, I'd guess, the main factor which causes the inboard wing to stall.  Blanking of the inboard wing by the fuselage as the yaw is established is a contributing factor.  And if you try to correct the rolling motion with aileron, it just stalls the inboard wing worse.  The video linked to above also discusses the swept wing effect causing the center of pressure of lift to move outboard on the outside wing and inboard on the inside wing.  On that, I'll just have to take the gentleman's word.  But the point is there are multiple factors which cause the inboard wing to stall deeply and the outboard wing to stall lightly (or not at all).  The discussion reminds me of left-turning propeller effects, which are not due to a single factor, but rather caused by a combination of P-factor, spiral slipstream, and in some cases torque and gyroscopic force.  I'd guess this is the reason PTK and jetdriven have contrary evidence with respect to evidence of buffeting: there are a lot of factors at play, and you may or may not feel buffeting during spin entry, depending on the airplane, the conditions, and the spin entry technique.

 

1 hour ago, 201er said:

I'm curious how many knots faster than stall would be slow enough that an addition of excess skidding rudder would cause the stall. How much speed worth is the skid. Or in reverse, how many knots over "stall speed" is there insufficient rudder to cause a skid stall.

I just don't think you're going to get even a ballpark number for this.  Too many factors at play: rudder size, travel, shape, rudder moment, how fast/hard your control inputs are, whether you're subconciously inputting aileron as well, your current CG, etc.  I certainly don't think you can develop a numeric rule of thumb like "an extra 11 knots of airspeed speed protects me against a skidding stall".  Hence the focus on teaching coordinated turns.

 

1 hour ago, 201er said:

I think the advantage of an AOA indicator is that you would already be referencing an AOA with a safer margin in the turn in the first place giving you adequate overhead.

No disagreement from me on this.  Both airspeed and AOA indicators are proxies for "true" AOA (which may vary at different points along the wing).  An AOA indicator is a better proxy.  But whether this difference in accuracy can actually reduce the stall/spin rate across the fleet is a more complicated question.  My guess is that as with motorcycle helmets, anti-lock brakes, airbags, and full airframe parachutes, the safety improvement is undermined to some degree by the human tendency for risk homeostasis.

[Browncbr1]

I have a 67 F with the twisted wing ( some washout at the tips). 

I trained and took my check ride in it.  I have done many stalls.   Power off, it is uneventful. Nose drops a little and immediately starts flying again.   Power on stalls is where you can get in trouble.  If you don't have enough right rudder, it will start to go into a spin pretty quickly.   Right rudder to the floor is needed with a power on stall.     I didn't enter a full spin because I took action to not allow it to completely enter, but I will say that the effect of the rudder to get out of that situation was much less effective than the Citabria.  My guess is that if you enter a full spin in the mooney, it will require 2 or 3 revolutions to get out.  Just a guess based the rate of authority the rudder seemed to have then..  I could be wrong, but I'm not interested in testing that theory and it isn't certified to do that intentionally anyway.   Anyhow, give how much rudder is needed with power on stall, it would make sense that it naturally skids if right rudder isn't used, which causes the spin..  Thus, I think a skid stall immediately precedes a deep spin..

Part of my training was in a Citabria where we did a lot of aerobatics, spins, etc.  I never tried a cross controlled stall in the mooney and have no desire to try.   I am very comfortable doing them in the Citabria though.  

Edited September 9, 2016 by Browncbr1

[DXB]

Requesting clarification here: 

Some folks here indicate that both slipping and skidding stalls are more dangerous than a coordinated stall, whereas as others only implicate the skidding stall as the bad actor leading to spins - I was in the latter camp, but I could be wrong. I was under the impression that a stall in a slip does not lead to a spin and is no worse than a coordinated stall. In fact it may actually be better - i.e. the high wing drops, taking you out of your bank and thus automatically reducing the high load factor that contributed to your stall in the first place.  So it would seem that one could avoid a spin in a steep banked turn by simply keeping ones feet off the rudder and letting the slip happen - no style points for that, but safer than actively trying to center the ball and ending up in a skid by accident?  And the linkages between rudder and aileron in my plane tend to keep the ball from slipping too far inside even if I do nothing at all with the rudder in a turn.   

On a related note, it's taken me a long time to visualize intuitively how side and forward slips are never actually skids in practice.  Now that I get it (I think?), it's made me more cavalier about forward slipping to dump altitude when high on final.  Am I stupid in thinking this way?

[Hank]

I sometimes slip on final,if too high, but not in the base-to-final turn. Usually I will add more Flaps Down and reduce throttle. This even works at my previous & current fields of 3000' and 3200' as it allows me to keep my desired speed of 85 mph slowing to 70-75 by weight on short final. (I have little experience at airports with fences, so I'm not sure how far out "over the fence" is. It's only been since leaving WV in 2014 that I've had to adjust to airports with open, unobstructed zones at both ends.)

[carusoam]

Injecting some additional complexity....

1) Remember that removing controls from the 'slip' should be done as equally gently as the inputs are put in.

Letting the pedals slip out from under your feet turns into the equivalent of stomping on the other pedal.  The tale snaps towards bringing it in line and the momentum carries it past that line.

Picture a new pilot familiar with slips, but forgot the second part of that piece of information.  Done on final approach because it seemed cool to let the tail snap back to center the ball.

 

2) Weight and balance adds another level to this conversation.  

 

3) Side effects that you get with the use of each control surface. 

Dev,  I think you mentioned letting the tail do whatever it wants?  I would consider putting in inputs that are required to keep the ball centered.  The reason for this is the aerlerons induce some uneven drag at the wing tips, the rudder is used to balance out the uneven forces.  

 

4) consider the momentum generated  when applying or removing control inputs.

 

5) See if I recall this correctly....  Stalls and Mooney wings: the stall begins inboard, where the stall strips are located, and away from the tips where the aerlerons are placed.  

In the early phase of a stall, the stall strips interrupt the air flow going over the wing, causing the first separation to occur early on.  This provides some buffeting, at the cost of a small loss of lift.  The stall horn is generally on at this point.  Check out the length of the stall strips, they aren't very large to be effective. Similar to speed brakes, small devices with a large impact.

 

Just private pilot ideas, not a CFI.

 

Best regards,

-a-

 

 

[Vance Harral]

1 hour ago, DXB said:

I was under the impression that a stall in a slip does not lead to a spin and is no worse than a coordinated stall.

No, that's not correct.  A slipping stall still results in an incipient spin.  It's just that the incipient spin rolls you toward wings level instead of away from wings level.  Therefore, application of prompt recovery technique results in you breaking the stall about the time the wings are level with the horizon, This makes it easier/faster to level the wings with the rudder, and you don't lose as much altitude.  But if you don't apply prompt recovery technique, you'll continue the outside snap roll and wind up in a spin opposite the direction you would spin from a skidding turn.

Here's a video that shows a one turn spin from a slipping turn.  The airplane snap rolls left, away from the right turn:

 

[DXB]

30 minutes ago, Vance Harral said:

No, that's not correct.  A slipping stall still results in an incipient spin.  It's just that the incipient spin rolls you toward wings level instead of away from wings level.  Therefore, application of prompt recovery technique results in you breaking the stall about the time the wings are level with the horizon, This makes it easier/faster to level the wings with the rudder, and you don't lose as much altitude.  But if you don't apply prompt recovery technique, you'll continue the outside snap roll and wind up in a spin opposite the direction you would spin from a skidding turn.

Here's a video that shows a one turn spin from a slipping turn.  The airplane snap rolls left, away from the right turn:

 

Nice- makes  sense, and video visual nails it - thank you.  It does seem to give you more chance  to recover.  Another question-  do we not get these violent wing drops when slipping to correct for x-wind in the flare over the runway?

[carusoam]

Stalling while cross controlled is going to be disastrous in the traffic pattern.

hence the long discussion...

The LB got more attention to this situation because of the distance from flaps to tail can cause a tail stall. The solution is a pair of speed brakes.  No slips on final with flaps in landing configuration.

Best regards,

-a-