Talk:Leading edge cuff

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Title[edit]

I suggest either to rename the article "drooped leading edge", or a redirection

  • Accounting for the numerous works/papers done by the Nasa,
  • "cuff" means an add-on rather than a design concept (present at the beginning of the design). A drooped leading edge may be directly built (Cirrus, Lancair) (no cuff) or added (cuff). Cuff LE is a subset of drooped LE. — Preceding unsigned comment added by Plxdesi2 (talkcontribs) 16:52, 26 April 2013 (UTC)
I disagree, several manufacturers, including Cirrus and Cessna, have described their modified wing designs as having "cuffs", so there is ample reason to use that term here as WP:COMMONNAME. - Ahunt (talk) 22:02, 27 April 2013 (UTC)
Cirrus and Lancair (then Cessna) LE cuffs are based on wing LE modifications, wisely described, for example, in Spin Resistance Development for Smal Airplanes-A Retrospective, Stough /DiCarlo. In this 27 pages report, one can read :
  • "cuff" : zero occurence (true !)
  • "LE modification, or Wing ..., or Wing outboard ..., or Outboard wing ..., or modified outboard LE" : 34 times
  • "drooped wing LE, or outboard wing LE droop, or outboard LE droop, or (outboard or wing) drooped leading edge : 41 times
Despite these figures I understand that "cuff" is a "common name". Drooped LE seems a technical term. Plxdesi2 (talk) 18:32, 28 April 2013 (UTC)
In NASA droop concept [1], Joseph Chambers (NASA team leader on the project to develop the droop concept at NASA Langley Research Center) uses "NASA droop", "droop concept", "drooped leading edge, leading-edge droop". He did not used "cuff" either. Interesting, he wrote also "we wanted people to stop calling the concept a "droop" because it conjers up the wrong vision in people's minds. The leading edge add-on does not droop below the lower surface of the airfoil. We called it the MOLE for Modified Outboard Leading Edge." Plxdesi2 (talk) 08:13, 29 April 2013 (UTC)

Aviation Management : Global Perspectives[edit]

Some article text was copyed from this book ;
"Leading edge cuffs are a ...device to modify the airfoil used. This (drooped leading edge) has effect of causing the airflow to attach better to the upper surface of the wing at higher Aoa, thus lowering stall speed. A secondary benefit is to produce a more gentle stall onset, particularly when the original airfoil had a sharp leading edge shape."

The author did not well undersand the aerodynamic action of a modified outboard leading edge : outboard cuffs are used to modify not the airfoil but the wing flow ; that is not a 2D (airfoil) improvement but a 3D matter (vortex lateral control of spanwise separated flow). Chambers comments : "that stall is really a 3 dimensional issue, not just 2-D airfoil stuff!".
"Gentle stall onset" is not a "secondary benefit", it is the very objective of the Nasa program. The author seems do not know that an asymmetric stall is much more dangerous than a high stall speed.
Drag penalty section was also copyed from this book, in disagreement with Nasa report. Plxdesi2 (talk) 10:23, 29 April 2013 (UTC)

...sharp leading edge shape[edit]

"...a more gradual and gentler stall onset, particularly where the original airfoil had a sharp leading edge shape. [1]

The aircraft (Questair Venture) given in the Cox paper has a Naca 23012 rounded nose airfoil, different from a "sharp leading edge shape". This shows again that outboard stall/spin matter is not only an airfoil (2D) issue. Plxdesi2 (talk) 12:01, 29 April 2013 (UTC)

Quotes from forums[edit]

Please stop adding forums as refs as this contravenes WP:SPS. Despite claims in the forums, you have no confirmation who these anonymous forum posters are, which is why we have a policy against using these sorts of refs. if this information is important and valid it will have been published in a real WP:RS somewhere. - Ahunt (talk) 12:33, 29 April 2013 (UTC)

When J. Chambers cites his name and his Nasa role in a forum, this is not an "anonymous" post.
WP policy : "Self-published expert sources may be considered reliable when produced by an established expert on the subject matter, whose work in the relevant field has previously been published by reliable third-party publications".
- established expert on the subject matter : yes, conversely to K. C. Khurana
- work in the relevant field has previously been published : yes, Nasa reports
- by reliable third-party publications : NASA
So Chambers quotes are reliable. Plxdesi2 (talk) 15:14, 29 April 2013 (UTC)
The problem with random internet forums is that you can't confirm that the poster is who they say they are. Posters can claim to be anyone. The use of personal websites posted by people who are published in the field is a different matter and is permitted under WP:SPS. It all comes down to reliability of sources . We seem to have sourced most of the article now without resort to forums and that is a good thing! Ref 18 is still an issue - there is no indication where that one was published. - Ahunt (talk) 16:40, 29 April 2013 (UTC)

Drag penalty - Khurana[edit]

According to K. C. Khurana book extract in the article :
"In the case of the modification of the AA-1 Yankee to the AA-1A Trainer the loss of cruise speed amounted to 8 knots or 7%, which is not uncommon."

AA-1 Yankee cruise speed is 125 mph. With a 8 kt (9 mph) loss of speed, the power penalty is (125 / 116)^3 = 1.25 that is 25 % ! (or a bit less because induced drag decreases with speed). The author confused delta V with delta drag (1.07). In fact delta V is about 2 %, as (1.023^3 = 1.07).
"which is not uncommon" : no examples given. Nasa/other reports give a loss of speed about 1 - 2 %
It seems that this kind of false information, not sourced, not corrected, is more of a concern than J. Chambers post reliability. Plxdesi2 (talk) 16:56, 29 April 2013 (UTC)
In the 8 august 2009 revision, following Erik9bot [Category:Articles lacking sources] request, the added reference [3] [2] about AA-1 did not quoted the book from which the text was copied out, and did not contain a single word on the subject (cuff drag penalty) either, contravening [WP:IRS] : "Sources should directly support the information as it is presented in an article". Plxdesi2 (talk) 09:31, 30 April 2013 (UTC)

Applications[edit]

"Where a factory modifies an existing design by the addition of a leading edge cuff it is often due to an identified problem or deficiency in the original airfoil used. One example of this is the American Aviation AA-1 Yankee, which was modified with the addition of an outboard leading edge cuff to become the AA-1A Trainer. This was a result of flying schools operating the Yankee demanding a lower approach speed and gentler stall characteristics from the manufacturer.[21][22][23]"

The AA-1 is not "one example of this", because it was not modified by the factory (1968-1978), but later by Nasa experimenters (1979 and later).
The AA-1 Trainer is a 1971 model, of course without outboard leading edge cuff, see ref [21].
The [21][22][23] references are general papers about the aircraft (description, handling qualities) but do not describe "flying schools demanding a lower approach speed and gentler stall characteristics" from manufacturer or Nasa stall/spin program team.
As for "Drag penalty - Khurana", that is a full-copied, unverified, uncorrected and misquoted information. Plxdesi2 (talk) 10:10, 30 April 2013 (UTC)