Talk:Stall (fluid dynamics)

message: I'm going to turn this into a disambiguation page, then create a new 'Stall (flight)' page to cover this subject.  There are too many legit other stall definitions, and the (flight) modifier will be consistent with other flight pages, such as Spin (flight).  I'll move the discussion over to the new page so it stays with flying stalls, any objections? - Chairboy 20:36, 19 July 2005 (UTC)
replies: text: Sounds like a good idea to me - go for it. Graham 01:20, 20 July 2005 (UTC)
replies: text: I went for it.  Created Stall (disambiguation) and put a link at heading of Stall (flight) to go to it.  There are a bunch of pages that link to Stall that should have autolinked to Stall (flight), this method should reduce the workload that converting all of them would require. - Chairboy 16:35, 22 July 2005 (UTC)
replies: text: This seemed needlessly tangled, since all the links to stall were meant to go to stall (flight).  I created stall (enclosure) for all the other meanings and left a link at the top here, then  moved this back to Stall.  Thanks to those who started cleaning up links immediately; I got called away from the computer right after the move and came back to get started with cleanup only to find most of it done!  Thanks, — Catherine\talk 19:18, 3 March 2006 (UTC)

text: OK, I did that and I am currently working through the double redirects. Paul Beardsell 16:39, 30 September 2006 (UTC)
thread_title: Disambiguation

message: The recently added image includes a caption "tilt with respect to horizontal plane". Thus MUST be changed to "tilt with respect to airflow", otherwise it is simply incorrect. In addition, the images themselves are a bit misleading to my mind. An unstalled wing shouldn't be shown with a trail of turbulence left behind, since this isn't there. The flow is smooth. Graham 05:37, 13 February 2006 (UTC)
replies: text: On further thought I decided to temporarily remove the image from the page. It can be reinstated once the problems are fixed. I decided to do this because anyone coming to this article with this image in its current form will leave with the wrong information. We don't want that to happen, and since the text is OK, this is the best way forward that I can see. Graham 05:40, 13 February 2006 (UTC)
replies: text: The more I think about it, the more troubled I am by this image. I think it should not be reinstated. I have written a criticism of it at . Most surprising is that the image was sourced from NASA - they ought to know better than this. Graham 05:50, 13 February 2006 (UTC)
replies: text:  Wow, that is bad.  I don't know aerodynamics very well, but maybe we can patch things up with Photoshop.  I've uploaded two new versions, one with the "with respect to airflow" change, because that's blindingly obvious.  The latest version has an additional airfoil diagram at the top for 0° that says "laminar flow, no turbulence".  Does that latest version of :Image:StallFormation.gif look correct?  --Interiot 09:50, 13 February 2006 (UTC)
replies: text:  Good work on the caption. Unfortunately I'm still unhappy about the rest. There simply is no "separation point" in existence until the onset of the stall - so the images at 4° and 8° are still wrong. I'm not even sure that the approach of describing the stall as an existing separation point moving forward is going to get us anywhere, especially as the article itself doesn't take this approach - in fact "separation point" isn't even mentioned. At the onset of the stall there is an airflow detachment or separation, but it comes into being at that time - yes, it moves from the trailing edge forward as the AoA increases, but this change occurs over a very narrow range of angles close to the stall (say from 15° to 17°). AoA less than that are fully laminar. I think NASA must have commissioned this artwork from a graphic artist who was given a rough description to go on with few details, and basically got it wrong. A simple fix would be to change the captioning of the angles - change 4° to 15°, 8° to 15.5°, etc, but a better fix would be to change it more radically by showing the more conventional "airstream" lines that usually are used (in fact, that's another thing - the portrayal of the turbulence here looks like the wing's on fire or something - it doesn't properly illustrate what is happening all around the wing.) However, let's get some other views on this before entering into a load of edits. It might even be better to start over - I might look into doing it myself if I can make the images look decent. Graham 22:23, 13 February 2006 (UTC)
replies: text:  Yeah, I don't fully understand the topic myself, but have a bit of Photoshop experience, and would love to find/create an image as necessary.  Okay, next proposal: we just have two wings, one at 13° that shows 100% laminar flow lines around the wing (eg. like this).  And then below that, a wing marked "15°, stall point", something like what's there now or this or this, with the laminar flow lines going around the wing, except for the separation region.  Also, if the article doesn't mention "separation point", should that phrase be left off?  Or, I've seen other pages   refer to it as the "transition point" as well, would that be more appropriate?  --Interiot 23:59, 13 February 2006 (UTC)
replies: text:  Sorry to challenge what some of you have written, but as an Aeronautical Engineer I have to say some of the statements above are wrong. To begin with, unstalled wings often DO leave a turbulent wake behind. A wing that is 100% laminar wouldn't leave a wake, but these are practically impossible - almost all wings are turbulent, and so leave a wake behind, even in normal unstalled flight. This turbulent wake accounts for a significant portion of the aircraft's drag. Secondly, the 'separation point' nearly ALWAYS exists on a wing. As shown on the image here, it's the point at which the boundary layer 'trips' from laminar to turbulent, increasing dramatically in thickness. This point exists on all normal wings, and is not related to stalling.  --dSpammer 22:00, 13 August2006 (BST) 
If you are willing to make the images, that would be great. I started to have a go but I got very frustrated with the free dumbass drawing package I was trying to use (Eazydraw) which makes drawing basic bezier curves unnecessarily complex. Anyway, I think your proposal sounds good - an unstalled wing at some angle (it doesn't need to be 13°, anything reasonable - say 6°, which is a typical AoA in straight and level flight) with laminar flow lines and no turbulence, separation point or any of that malarkey. Then a wing partially stalled (15° say) where the flow is laminar over the first half or so, then breaks away, and one fully stalled where the flow is not attached at all, and spills over the leading edge. Those photographs you linked are very informative and could well be used as a basis - the depiction of turbulence is difficult and just using hatching is a bit lame - some sort of eddying would be great. I think we should avoid using any captions that mention 'separation point' - it should be obvious from the drawings that the airflow has detached and that ties in with the description in the text. Graham 04:24, 14 February 2006 (UTC)

text: Okay, the image isn't perfect, but I uploaded a new version.  Since I don't even know what a proper airfoil is really shaped like, it's a more conservative modification of .  If there's a good sharp image of what turbulence looks like, I might be able to trace that.  But is the latest version of the image semi-acceptable? --Interiot 18:38, 25 February 2006 (UTC)
replies: text: Much, much better. The only comment I'd make is that in the 25° case, the separation point could be right "on top" of the foil's curve, rather than further back as it is now, but if it's a lot of work to change it then it's acceptable anyway. Graham 03:21, 26 February 2006 (UTC)
replies: text:  Done.  Although note that the 25° one was previously unmodified from the original image, so it may have been okay as it was before too.  --Interiot 20:18, 26 February 2006 (UTC)
thread_title: Image captioning problem

message: A proposed merger of Stall speed into this article has been sitting around for over a year.  It makes sense to me, and shouldn't be too hard to accomplish.  Any problems? PubliusFL 19:58, 10 January 2007 (UTC)
thread_title: Proposed merger: Stall speed

message: is stall strake the same thing as a stall fence? --Kvuo 02:10, 17 June 2007 (UTC)
thread_title:  Stall fence 

message: Have just deleted a short paragraph. Jan 28 2008. Don't think it will upset anyone, but will provide a brief justification here in case: Paragraph seemed to be written by someone thinking of a particular class of aeroplane. Not reasonable to say that non-pilots will be worried (with the implication that pilots will not be worried) for all aircraft. For some aircraft pilots will be worried too. Anyway even pilots will be worried if it's accidental. And the point about height is made elsewhere in the article. Assuming nobody objects for a few weeks (say by the end of Feb 08) then please feel free (anyone) to delete what I've written here as it will cease to be of any interest. Rowmn (talk) 23:22, 28 January 2008 (UTC)
thread_title:  Deleted short paragraph Jan08

message: This article was automatically assessed because at least one WikiProject had rated the article as start, and the rating on other projects was brought up to start class. BetacommandBot 10:03, 10 November 2007 (UTC)
thread_title:  WikiProject class rating

message: The "misconception" of engine stalls being related to areodynamic stalls is not actually a misconception at all (for jet engines). An engine stall happens when the engine compressor blades stall out, the same sort of aerodynamic stall as described for the wing. That tends to cause reverse flow (known as surge), resulting (often) in an impressive fireball shooting out the front of the engine.
It's also possible for a compressor stage to have a "partial" stall. In that case one stalled blade makes the next one stall. The that one makes the next one stall. Etc. But the first stalled blade recovers. That recovery makes the next one recover. Etc. So a "stall cell" rotates around the stage.
Thus, claiming that engine stall is an unrelated misnomer is wrong (for jet engines, anyway). It's actually a very closely related phenomenon. (What people call an engine stall in a piston engine is a different matter.)
Furthermore, the entire section was unattributed, and there was no evidence given that this is a "popular" misconception. In my personal experience, almost everyone understands that planes can glide and that losing lift on the wings is not related to a car engine dying if you forget to declutch at a stoplight.
—Preceding unsigned comment added by 130.76.32.181 (talk) 22:44, 19 January 2009 (UTC)
replies: text: There is a whole article on compressor stall.  On the other hand, it is only mentioned here in the See also.  Should it be mentioned earlier in the article, especially if, as above, the physics is the same?  Gah4 (talk) 00:12, 2 August 2019 (UTC)
thread_title:  Engine stall section seems misleading 

message: In the Graph section, it is stated 'very few aircraft have an angle of attack indicator.' But further down the page, in the Stall warning and safety devices it says 'Many aircraft have an angle of attack indicator '. Which one is right? 
Abercrombiefiz (talk) 07:02, 12 February 2009 (UTC)
replies: text: I have changed the latter comment to say Most military combat aircraft have an angle of attack indicator ... ...  Dolphin51 (talk) 11:39, 12 February 2009 (UTC)
thread_title:  Angle of attack indicator 

message: Hi all, how about adding a section on tail stalls? They have been implicated in some recent crahes... Cheers MC MarkC (talk) 14:53, 5 June 2009 (UTC)
thread_title:  Tail stall 

message: :W = L \times cos(bank\ angle)  —Preceding unsigned comment added by 200.255.9.38 (talk) 11:42, 18 January 2011 (UTC)
thread_title:  Turning flight stall 

message: Needs a "history" subsection. I remember reading someplace that Orville accidentally "discovered" this on a flight at Fort Myers where a passenger was killed, and Orville badly injured for life. It seems odd now, but they were bent on "flying" and hadn't quite got around to analyzing the practical aspects of "not-quite-flying." Student7 (talk) 14:50, 1 October 2011 (UTC)
replies: text: Another editor researched this. See Talk:Fort Myer. Student7 (talk) 13:26, 22 October 2011 (UTC)
thread_title: History

message: I apologize in advance if this is the wrong place to submit suggestions - but I am absolutely LOST in this Wiki hierarchy! :) 
I would like to submit a suggestion that the subject of "Tip Stall" (aka 'Wing Tip Stall') be incorporated into the section/page titled 'Stall (flight)'. 
A quick Wiki Search will advise such page doesn't exist, however it will also show the term is mentioned prolifically in many other places. I can assure you it is a topic of great interest (and concern) in model aviation circles, for one, and from both eyes-on experience and much reading there is obviously a LOT of confusion as to what a tip stall actually is, ie confused with other aeronautical actions eg accelerated stalls & turning stalls. It would be very nice to have a Wiki reference to cite to those lost souls who don't really know what they did wrong or what actually happened. I would readily volunteer to submit such info but lack the technical expertise for Wiki submissions & especially for the proper way to integrate it into the existing Stalls (flight) page.  
Respectfully submitted,
and thank you for listening.
~Jay F — Preceding unsigned comment added by 184.3.66.204 (talk) 11:37, 24 August 2012‎
:This is the perfect place to submit suggestions aimed at improving the coverage of this subject. Thanks for drawing it to our attention.
:I agree that Wikipedia should have coverage of the phenomenon known as tip stall. It doesn't warrant its own article but it can be covered in one or more of the existing articles. The only existing articles that touch on the subject are this one, Spin (aircraft) and Autorotation (fixed-wing aircraft).
:Everything written in Wikipedia articles should be attributed to a reliable, published source. The most common reason that Users haven't yet written material on a particular subject is that they don't have suitable reliable, published sources to which to attribute what they know to be correct. Do you have a good source for material on tip stall? 
:Don't forget to sign with the four tildes (ie four wriggly lines. On my keyboard, the tilde is the key in the top left corner.) Dolphin (t) 12:18, 24 August 2012 (UTC)
thread_title:  Tip Stall 

message: A picture of a stall with a paraglider, maybe something for this article.--Luxo (talk) 22:11, 24 January 2013 (UTC)
thread_title:  Stall with a paraglider 

message: In the lead to Stall (flight) there is presently a diagram depicting deep stall.  It is the same diagram as the one that is used later in the article to support the sub-heading Stall (flight)#Deep stall.  Duplication of an image is discouraged in any article unless there is a really good reason.  Deep stall is a rare form of the stall phenomenon so a diagram that targets deep stall is not a good one in the lead to this article.  If there is to be an image accompanying the lead I think it should be an image appropriate to the general form of aerodynamic stall that occurs at high angle of attack in most aircraft. I am in favor of deleting the deep stall diagram from the lead to this article. Dolphin (t) 10:19, 15 July 2013 (UTC)
replies: text: I agree! Do we have a better lead image? - Ahunt (talk) 11:10, 15 July 2013 (UTC)
replies: text: How about the image in the lead to Flow separation? Dolphin (t) 11:55, 15 July 2013 (UTC)
replies: text: That one is okay. - Ahunt (talk) 13:01, 15 July 2013 (UTC)
replies: text: Done. See the diff. Dolphin (t) 08:20, 16 July 2013 (UTC)
thread_title:  Duplication of images 

message: Wondered if we wanted to add this to the page:
http://dx.doi.org/10.1017/jfm.2013.440
From the abstract: Computed results show agreement with marginal separation theory at low and with available experimental data at higher. This simplified approach provides a universal criterion to determine the stall angle of stationary thin aerofoils with a parabolic nose.
Research has been published in Journal of Fluids Engineering and Journal of Fluid Mechanics.  — Preceding unsigned comment added by 75.81.139.106 (talk) 03:36, 15 October 2013 (UTC)
thread_title:  Analytical prediction of stall onset 

message: I modified the article to clarify the difference between the aircraft 'nosing down' by itself, and the pilot 'nosing down'. I was careful to avoid implying that once the nose has dropped, the pilot must lower the nose further in order to recover from the stall. [this] further edit was intended to simplify, but the article now appears to imply just that. 
Some texts are not very clear about this but I have just checked Langeweische, Stick and Rudder, p.33. It says that when the nose drops in the stall, the aircraft is already attempting to recover by itself. If the pilot removes his back pressure which created the stall, it will recover. Also, [FAA Advisory 120-109]
p. 14, requires a, "nose down pitch control". 
In my stalling training, I had to learn not to lower the nose too much and lose more altitude than necessary in the recovery. I understand that a nose-down control movement is what's required at this point, not necessarily forcing the nose to drop further. 
I suggest a different wording is needed. Burninthruthesky (talk) 16:02, 24 July 2014 (UTC)
replies: text: You make a good point - in most light aircraft the nose only needs to be lowered once, either by the pitch-down effect of the stall itself or by pilot input, but not really both. I have further simplified the wording, but see if that is an improvement or not! - Ahunt (talk) 16:53, 24 July 2014 (UTC)
replies: text: I like your thinking. I think it's best for the article not to get bogged down in unnecessary detail. Thanks. Burninthruthesky (talk) 18:33, 24 July 2014 (UTC)
replies: text: That was my approach, keep it simple! - Ahunt (talk) 18:42, 24 July 2014 (UTC)
thread_title: Nose down control, or lower the nose?

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replies: text: - Ahunt (talk) 23:01, 3 April 2016 (UTC)
thread_title:  External links modified 

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thread_title:  External links modified (January 2018) 

message: Should MCAS be mentioned or discussed in this article? Gah4 (talk) 18:07, 19 March 2019 (UTC)
replies: text: No, why would it? Tens of thousands of aircraft accidents have involved stalls. One or two new accidents are not notable to this topic. See WP:RECENTISM - Ahunt (talk) 18:19, 19 March 2019 (UTC)
replies: text: No, not the accidents, but the system for preventing stalls. Yes, specifically, the accidents are not notable here. It does mention stick shaker, but not (I might have missed) how it detects them. Gah4 (talk) 20:31, 19 March 2019 (UTC)

text: OK, it does mention stick pusher, and I suppose MCAS should be a subset of stick pusher. It is is exactly stick pusher, then it wouldn't be new, and likely not a fancy new name. Should MCAS (again, without mention of accidents) go into stick pusher?  Gah4 (talk) 20:36, 19 March 2019 (UTC)
replies: text: The MCAS is more than a mechanical stick shaker or stick pusher. It is adequately covered here right now. That links here, which is appropriate. I can add a "see also" to stick pusher. - Ahunt (talk) 22:06, 19 March 2019 (UTC)
thread_title:  MCAS 

message: I propose that the article Post stall be merged with this article (and Post stall be converted to a redirect.)
Post stall has been in existence for a dozen years but it contains little information. The information it contains is technically incorrect because it states that post stall behaviour is a function of airspeed whereas, in fact, post stall behaviour is a function of angle of attack. If anything can be salvaged from Post stall it can be inserted into this article. Dolphin (t) 13:11, 23 September 2019 (UTC)
replies: text: I agree, it should be merged in here, redirected and the merged text fixed so the text is about angle of attack and not airspeed. Plus I would question why it is included in the navbox on aerial warfare! Nothing in that stub relates to its possible uses in air combat. - Ahunt (talk) 13:38, 23 September 2019 (UTC)

text: I agree too! -- Ariadacapo (talk) 07:13, 24 September 2019 (UTC)
replies: text: I have begun merging "Post stall" with this article - see my diff. I have also removed "Post stall" from the Aerial warfare navbox. Dolphin (t) 13:11, 2 October 2019 (UTC)
thread_title:  Proposed merger: Post stall 

message: * απάντωση, from απο- and άντωση
* https://el.wiktionary.org/wiki/απο- (here it means removal) — Preceding unsigned comment added by 2a02:2149:8844:a300:40d2:8f7f:20bf:767 (talk • contribs) 
:Can you explain your point with regard to this article? - Ahunt (talk) 15:09, 6 September 2021 (UTC)
thread_title:  Greek translation: απώλεια άντωσης f 

message: I'm no expert, just someone who wants to learn. There is no explanation of how a canard-winged aircraft can get into a deep stall, which is defined by the article as turbulent airflow from a stalled wing at such a high angle of attack that it interferes with the tail control surface effectiveness and possibly rear-mounted turbine engines. The article notes that two Velocity (canard-configured) aircraft crashed due to deep stalls, but there is nothing in the area that would be affected by the turbulent air from a stalled wing in such aircraft, no control surfaces, stabilizers, or engine inlets. The [Aviation Safety Network] article on the Piper Advanced Technologies crash says it was likely a flat spin, not a deep stall. Yes, I would like to know how this works, but more importantly, I think the article needs to explain how this works. Thanks! Dcs002 (talk) 01:15, 8 August 2023 (UTC)
thread_title:  Deep stalls and canard-configured aircraft