Skidding turn stall

[kortopates]

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:

 

This is only true with power in a positive attitude. The fact is you can't make such statements about a slipping turn without inclusion of power as to the configuration. At idle in a descending turn, such as our traffic pattern, a stalling slipping turn is mostly benign with the high wing un-stalling as it falls level. In fact in many trainers you can't even get it into a full stall. This is all in a huge contrast to skidding turns where both power on and power off you will be in for a big e-ticket ride down. But the aforementioned thought that any cross controlled stall will lead to a spin is utterly false and leads way to many pilots to being afraid of slipping their aircraft in the pattern.

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[midlifeflyer]

18 hours ago, Vance Harral said:

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.

Excellent post.

I have not done them in a Mooney but have done cross-controlled stalls in Pipers and Cessnas and would do them in any airplane in which I gave primary instruction. Like you, I learned them as one of the "demonstration" stalls during my CFI training. I really liked it much better than the other ones and think it is an excellent way to show how an airplane does not have to have its nose up in the air in order to stall. The demo comes when the student has already done "normal" stalls and the ypical comment Is: "I didn't realize it could stall with the nose so low!"

When I did my CFI ride I was given my choice of demonstration stalls. I chose this one. The examiner looked at me dubiously, tightened his seatbelt, and got very obviously in the "ready" position to take control. 

[midlifeflyer]

@kortopates, the video link did not come through, at least I don't see it on my iPad.

is this the one? Excellent demo, as usual, from BruceAir.

 

[carusoam]

They are the same video on my iPad Air....

Good morning,

-a-

[mike_elliott]

22 hours ago, N9201A said:

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!!

I had to demo it on my initial CFI checkride in my Mooney. When you plan for the event, that's one thing, its entirely different when the event "happens" and you have to figure out what "happened" and fix it. That takes precious time. Keep the ball centered.

[DXB]

9 hours ago, kortopates said:

 

This is only true with power in a positive attitude. The fact is you can't make such statements about a skidding turn without inclusion of power as to the configuration. At idle in a descending turn, such as our traffic pattern, a stalling skidding turn is mostly benign with the high wing un-stalling as it falls level. 

 

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Thanks great explanation- But I Think you mean to say "slipping" and not "skidding" in the statements above?

[kortopates]

9 hours ago, kortopates said:  

This is only true with power in a positive attitude. The fact is you can't make such statements about a skidding turn without inclusion of power as to the configuration. At idle in a descending turn, such as our traffic pattern, a stalling skidding turn is mostly benign with the high wing un-stalling as it falls level. 

 

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Thanks great explanation- But I Think you mean to say "slipping" and not "skidding" in the statements above?

Oops - yes, I meant slipping turn. I'll try and correct that so as not to confuse everyone. Thanks.

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[carusoam]

To Edit a post...

 

there is is an edit button at the end of each post that YOU wrote.

 

Best regards,

-a-

[kortopates]

To Edit a post...

 

there is is an edit button at the end of each post that YOU wrote.

 

Best regards,

-a-

It's actually different interface with Tapatalk but I found and corrected both instances.

Thanks!

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[kortopates]

This looks very likely to be a skidding stall since I'd bet almost anything it wasn't a slipping stall and surely not a coordinated stall. Reportedly the pilot survived this too which we all know is rare in these events.

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[DXB]

On 9/10/2016 at 2:13 AM, carusoam said:

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.

Anthony - can you elaborate on this a bit?   I'm "asking for a friend" who might forward slip his C on final once in a while with full flaps.  How bad is this really? Of course my 60s vintage POH is no help.  I remember hearing this about the 172, and I just found this article on Don Kaye's website saying it's ok up to J models but not Ks or long bodies:

http://www.donkaye.com/donkaye.com/Bob_Krommer_on_Mooney_Slips-Part_2.html

[kortopates]

28 minutes ago, DXB said:

Anthony - can you elaborate on this a bit?   I'm "asking for a friend" who might forward slip his C on final once in a while with full flaps.  How bad is this really? Of course my 60s vintage POH is no help.  I remember hearing this about the 172, and I just found this article on Don Kaye's website saying it's ok up to J models but not Ks or long bodies:

http://www.donkaye.com/donkaye.com/Bob_Krommer_on_Mooney_Slips-Part_2.html

Certainly not an issue with the Vintage Mooneys through the J's and won;t be an issue in the K's if your not aggressively slipping with full flaps either. After all, If you are landing with a strong cross wind we shouldn't be using full flaps while also side slipping to the landing because of the excessive descent rate we'll get with both full flaps and the forward slip. I have never experience wing buffet with partial flaps in my K but I also don't spend much time in the side slip instead preferring to kick into it during the flair which is also the recommended method in Mooney's latest longbody Mooney's. Bob K even says there is no danger here but some buffet as long as you are ice free (since ice will lead to accelerated airflow separation leading to a full tail stall) but he also emphasizes this is no place to be in the Mooney (slow, full flaps and in an aggressive slip) nor is there any needs to be there.

Often we hear at MAPA PPP's, pilots that have heard of this interpret it as one should never slip their Mooney on landing. A rather exaggerated response IMHO that robs the pilot of a valuable tool. 

[carusoam]

Dev,

Like practicing stalls...  Take it to altitude, in smooth air, and experiment following the procedure...

The LB (Long body) is known for having a challenge with full flap slips.  They all have speed brakes as a response.

An empty C is a very light weight machine compared to a full C.   The controls become less effective during the slower speed landing process.  The rotational momentum can become quite large compared to the control inputs.  Gently on and gently off the rudder inputs...

Some Cs have less rudder area, others have less rudder throw.  Keep the nose pointed downwards.  Turning the Mooney sideways adds a lot of friction!

Best to consult your CFI.  I'm only a PP.

Best regards,

-a-

[cnoe]

Definition of "slip": n. - poor man's speed brakes.

I practice this maneuver occasionally as well as various stalls and aggressive turns (with sufficient altitude). But I attempt to set up my landings so that they're unnecessary.

Still fun, and good for the soul (and confidence).

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[201er]

1 hour ago, cnoe said:

Definition of "slip": n. - poor man's speed brakes.

I practice this maneuver occasionally as well as various stalls and aggressive turns (with sufficient altitude). But I attempt to set up my landings so that they're unnecessary.

Still fun, and good for the soul (and confidence).

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Is this because you fly at places without approach obstacles and/or big runways? Cause you slow way the heck down to descend? Or cause you're just really good?

[cnoe]

Occasionally I fly somewhere that a steep/slow/short approach is needed, and I want to be proficient for those instances.

But your guess was spot-on. My home base is 7,000' x 100' at 25 msl with absolutely NOTHING to run into at either end. The challenge is not growing complacent about landings so I try to mix things up with a mixture of different approaches and spot landings, etc.  It's also good that we have a non-standard pattern (rt. traffic to 17 / lft. traffic to 35) so at least I'm not stuck in the rut of always flying counter-clockwise in the terminal area.

On the downside it's a very active uncontrolled field with a full compliment of aircraft including Cubs, RVs, warbirds, Coast Guard amphibs, a helicopter school, King-Airs, frequent business jets, and twice-daily regional jet service. "Most" pilots here give position announcements but I can't remember the last time I saw a plane over 6,000# actually fly in the pattern (it's always straight-in for them). Plus we have one of only a few ILS approaches here and get frequent student-traffic (straight in as well).

Just a couple of days ago I'm on the RNAV 17 approach calling a 5-mile final when the regional CRJ700 made their first call "8.5 miles straight in for RWY17". WHAT? I was 3.5 nm in front of them at 90 kts. so we worked it out on the radio (I made a left 360 at 500' below them) and all was well. I can only imagine what would happen under that circumstance if I had been NORDO (i.e. in a Cub). Fun stuff!

Oh, and I AM really good, but just an average pilot. 

[carqwik]

I would not recommend any turns underneath a jet on final.  We had a Cirrus crash at Scottsdale a few years ago due to wake turbulence from a landing Gulfstream biz jet.  The Cirrus was on base to final  right underneath the Gulfstream's path and ended up in the front yard of some home.  One of the two people managed to survive.

FMI: http://www.ntsb.gov/_layouts/ntsb.aviation/brief.aspx?ev_id=20111215X31833&key=1&queryId=a343d1e7-b6ef-4a0e-bc66-6a2637f39b65&pgno=2&pgsize=200

[cnoe]

Definitely good advice. My turn was to leave the approach to get away from him. Once he had me in sight and I had him in sight I rejoined the approach about 3 miles behind and upwind (crosswind) from him on the same glidepath. He was off the runway and on the tarmac before I called 2 mile final. I appreciate the comment though; it never hurts to be reminded of invisible gremlins.

[Vance Harral]

On 9/10/2016 at 0:17 AM, kortopates said:

This is only true with power in a positive attitude.

While it's true that power+attitude directly influences AOA at the wing, I can't agree with this statement.

I'm going to link to the BruceAir video again.  The pilot specifically says he is "bringing back the power" prior to demonstrating the spin from a slipping turn.  The nose appears level or slightly below the horizon for most of the turn (though I admit it's difficult to tell).  But it looks to me like the aircraft enters a spin from a descending, power-off turn, in direct contradiction to your statement above.  Now, this is an aerobatic airplane specifically designed to snap and spin easily, and it's fair to point out most GA airframes don't behave exactly this way.  But I still think your blanket statement is confusing and not really correct, and that the video demonstrates as much.

To be clear, I'm not arguing a power-off slipping turn is a risky maneuver.  I see them done all the time in taildraggers without incident.  I practice and use forward slips in my Mooney, too, though I choose to wait until the base-to-final turn is complete before doing so.  I'll also say my experience with stalls from slipping turns is limited to a few iterations in a couple of airframes, and always involved prompt recovery rather than allowing the spin to develop.  That's not a broad experience base, and I can easily believe some airplanes - e.g. a fat, straight-wing Cherokee - might do nothing worse than mush and wobble in a stable, descending, power-off, slipping stall.  But that would be a characteristic of the airframe, not a blanket statement, so I feel obliged to disagree with the gist of your post.

I'm always learning, comments and rebuttals are welcome.

 

[Vance Harral]

On 9/10/2016 at 0:05 AM, DXB said:

Another question-  do we not get these violent wing drops when slipping to correct for x-wind in the flare over the runway?

The "violent wing drop" is only caused by a stall in the cross-controlled condition.  If you don't stall, no wing drop.  Again, don't want to give anyone the impression I think a properly executed slip is a dangerous maneuver.  Entering an uncoordinated stall during a slipping approach isn't meaningfully more likely than entering a coordinated stall during a normal approach.

[takair]

58 minutes ago, carqwik said:

I would not recommend any turns underneath a jet on final.  We had a Cirrus crash at Scottsdale a few years ago due to wake turbulence from a landing Gulfstream biz jet.  The Cirrus was on base to final  right underneath the Gulfstream's path and ended up in the front yard of some home.  One of the two people managed to survive.

FMI: http://www.ntsb.gov/_layouts/ntsb.aviation/brief.aspx?ev_id=20111215X31833&key=1&queryId=a343d1e7-b6ef-4a0e-bc66-6a2637f39b65&pgno=2&pgsize=200

While I don't disagree with your recommendation, it is interesting that the NTSB does not discuss the Cirrus airspeed.  It seems quite possible that they may also have slowed down significantly to provide separation.  So, it may not have been purely wake turbulence, but may have been slow airspeed compounded by wake turbulence.  With adequate airspeed margin, I think most wake turbulence encounters created by a Gulfstream are manageable, but when the speed/AOA margin is reduced it can cause trouble......very much like our discussions here.

[JohnB]

This is great stuff guys, I remember learning from Don Kaye that a skidding turn on that base to final leg is treacherous and should never be done which I concur with. http://www.donkaye.com/donkaye.com/Inadvertent_Spins_in_a_Mooney.html

By looking at this video it appears that even a slipping turn can induce a spin on a base to final leg. I have always been leary to be in any uncentered ball position low to the ground in ANY kind of a turn. My takeaway from reviewing these videos is to do NO uncoordinated turns at low altitude, and slips or skids should only be done when traveling straight ahead with no turn involved with our Mooneys. Thoughts?

Edited September 12, 2016 by JohnB

[ArtVandelay]

I would just remove the "at low altitude" clause, there is no reason to do uncoordinated turn at any altitude.

[201er]

14 hours ago, JohnB said:

By looking at this video it appears that even a slipping turn can induce a spin on a base to final leg. I have always been leary to be in any uncentered ball position low to the ground in ANY kind of a turn. My takeaway from reviewing these videos is to do NO uncoordinated turns at low altitude, and slips or skids should only be done when traveling straight ahead with no turn involved with our Mooneys. Thoughts?

Nobody's practiced slipping turns for losing altitude?

[JohnB]

7 hours ago, 201er said:

Nobody's practiced slipping turns for losing altitude?

Yup sure have.. Did a great slipping turn base to final with Don Kaye in the plane during my transition training. Im just chicken to do one without Don Kaye in the plane. The video above with the spin induced from a slipping turn makes me a wee bit skeptical! But if i absolutely had to, im sure I could do a slipping turn to lose altitude, but I'd sure rather do a forward slip if i could!