Talk:Leading-edge extension

Scope?

I have just run through the high-lift device article and came here in the process. I would have thought that the scope of this article is just to describe the LERX and chine type of device. Most of the others have their own article, except 'Dogtooth' I think. Nimbus (Cumulus nimbus floats by) 11:45, 1 June 2010 (UTC)

Only the leading edge slat has its own article. The chordwise 'sawcut' slot needs adding - OK it's the opposite of an extension, but I think it's relevant. I would like to see this article grow a comparison between devices and discussion of their relative merits, such as use at high or low speeds, effect on spanwise flow, etc. H'mm maybe a move to Leading edge device might be useful, then we can discuss spanwise and chordwise slots too. — Cheers, Steelpillow (Talk) 16:59, 1 June 2010 (UTC)

Well slat shouldn't really be here ('slot' is not here?!). The dogtooth and saw cut do need to be covered and they will be in time hopefully. Wing fence we have! Might need to have a look at the categories to see what goes with what, possibly a separate navbox for high-lift devices (which is turning into a sort of overview parent article). In my own mind the LEX, LERX or Leading Edge Extension is specifically the type of device that the F-18 has (triangular bit at the wing root to be technical!).Nimbus (Cumulus nimbus floats by) 17:18, 1 June 2010 (UTC)

To say that something is a leading edge extension in ordinary language but is not technically a Leading Edge Extension (LEX) seems really bad to me. If you can find enough content for an article on just for that then I think 'leading edge root extension' is both technically more accurate and linguistically more sensible. Meanwhile, another sort of overview parent article, as you so enjoyably put it :-) , for leading edge devices still seems to me like a good idea, and fundamentally where the present article (and this discussion page) is headed. The more I think about it, the more I like the move to leading edge device. Sure the overview of high-lift devices is good too and the two device classes overlap, but they are nevertheless quite distinct. — Cheers, Steelpillow (Talk) 21:44, 1 June 2010 (UTC) [updated]

Problem is that my books are so old these things are not in them! I agree that you can't write an awful lot about a jazzy wing root fairing unless you have the wind tunnel notes to hand. I'm going round most of the aircraft component articles slowly and have just started an FAC which will sap my WP time for sure, we're getting there though. Nimbus (Cumulus nimbus floats by) 22:25, 1 June 2010 (UTC)

Chines

I think the definition of Chines is wrong. In boating, a Chine (boating) is a sharp change or crease in the profile of the hull. This also applies to seaplane hulls. So when an aircraft such as the Lockheed Blackbird is described as having "extended chines" what it means is that the side creases of the fuselage have been extended sideways. Compare this with the current definition as "long extension of the wing root along the forward fuselage". So I propose to change the definition along the lines of, "a sharp change or crease in the profile of the fuselage and, by adoption, the lifting surface which this produces. Such lifting surfaces are [also/more properly called] a form of strake [add refs]." What do others think? — Cheers, Steelpillow (Talk) 18:44, 22 April 2013 (UTC)

Following a look at the SR-71 front profile, a chine appears to be, as in nautical wording (hard chine) a longitudinal line, intersection of two angled panels of the body. By extension this term describes also the extended part of the body. As long as one cannot split the body in two separate components, the fuselage here and a distinct outboard component there, it's a chine. If the outboard component is thin, fitted at an angle to the body (generally at right angle), better to call it a surface according to his role (lift, control, stability, VG, whatever).

Definition : "a sharp change or crease in the profile of the fuselage and, by adoption, the lifting surface which this produces. Such lifting surfaces are [also/more properly called] a form of strake [add refs]."

In this definition, one can find again the unfortunately generalised approach to not consider the fuselage as a lifting surface. Example, the Saab Viggen image showing "in blue" the canard surfaces. As a result the canard lift eyeball estimate is highly underestimated (more than x 2). You guess the effect of this visual approach on balance/stability understanding. Doing the same in arbitrarily splitting the fuselage in lateral "lifting strakes" and a central part (non lifting as usual) is physically misleading especially when it is impossible to mark where ends the fuselage and where begins the strake. Plxdesi2 (talk) 20:38, 22 April 2013 (UTC)

"Blackbirds from the skunk works"

Although it is impossible to split the SR-71 front fuselage profile in two parts (fuselage and extended lifting parts), the writer uses the term "chines" all along the paper (more than 10 times), and "fuselage" term only one : "The low slender fuselage and its aerodynamic load distribution arising from the chines", imo trying to isolate and name a lifting device. The lifting surface is simply the fuselage, the lift slope of which being higher thanks to the chines. Plxdesi2 (talk) 13:40, 23 April 2013 (UTC)

That's a useful quote, thanks. A Lifting body is a fuselage which is also the *main* lifting surface. The wing configuration article treats aircraft designs as a continuum between various types. The Blackbird lies a little towards the "tailless delta blended wing-body" end of the winged vs. lifting body" spectrum, but the chines place it it is closer to the middle than one might think.

Having said that, in counting the "surfaces" for purposes of tailless vs, 2-surface vs. 3-surface classification, I have never seen anyone count the fuselage. One just counts the distinct horizontal planes attached to it. I guess that's because we say that the fuselage is a "body" not a "surface", as in the "lifting body" configuration. So the Blackbird has one lifting surface and one body which also contributes to the lift.

Either way, the chine is part of the fuselage. — Cheers, Steelpillow (Talk) 15:02, 23 April 2013 (UTC)

What all this does show is that chines have no real place in the present article on leading edge extensions, they are fuselage extensions. Strakes are a different matter, because they are separate surfaces from the fuselage body. — Cheers, Steelpillow (Talk) 15:05, 23 April 2013 (UTC)

There seem to be three "chines" in aircraft terminology. Those of the hulls of flyingboats and seaplane floats, the change in shape of conventional fuselage, and the dramatic lift-producing surfaces of the Blackbird etc. Could certainly do with some explanation even if one of them was part of a leading edge. (Has anyone put an aerodynamically contributing chine behind a wing?)GraemeLeggett (talk) 18:54, 23 April 2013 (UTC)

The sharp change in shape of the flying boat hull is almost certainly the origin of the sharp change in shape of the landplane fuselage: they both mean the same thing. The surface seems to have gained its name by popular association with the "extended" chine which forms its outer edge, and is the usage we most need to find authoritative references for (or against). The X-29A has surfaces extending back along the fuselage from the main wing, or maybe extending out from the fuselage behind the main wing, and these have been called "chines" and "strakes" in the same monologue - for more, see Talk:Three_surface_aircraft#X-29A_is_a_3-surface. In fact they may be neither, since both chines and strakes usually have a sharp outer edge whilst the X-29A's extensions are a shallow box section with a flat outer edge. — Cheers, Steelpillow (Talk) 19:57, 23 April 2013 (UTC) [copyedited 20:01, 23 April 2013 (UTC)]

"I have never seen anyone count the fuselage. One just counts the distinct horizontal planes attached to it... So the Blackbird has one lifting surface and one body which also contributes to the lift."

One can say also : a lifting wing and a lifting body, that is 2 lifting components ; as the chined lifting fuselage is distinct from the wing and clearly forward placed (for balance), it might be considered as a canard. And it actually resembles a canard in flight : long nose, aft wings, the very reason for the name. Some citations from "Blackbirds from the skunk works" :

1. The forebody chines are ... acting as a very low-aspect-ratio wing which produces lift as a function of the square of the angle of attack ... The long moment arm of the forebody to the centre of gravity, combined with this lifting function, makes the chines effective destabilisers... (note : as every forward surfaces).

2. The long, slender fuselage and its aerodynamic load distribution (arising from the chines) result in significant aero-elastic effects in pitch and roll, the chines acting as canard surfaces and being so effective as lifting surfaces that, at cruising speeds, the lift developed reduces the forward-fuselage bending moment by half.

I agree to not count a fuselage as lifting surface, but when the fuselage is different because designed to contribute significantly to the lift, the count becomes tricky. Can we have one, two and three surface layouts and a new SR-71 special 1.5 surface layout ? Plxdesi2 (talk) 10:20, 24 April 2013 (UTC)

Ha-ha, that would be interesting. But people talk of the fuselage as a "body" and not as a "surface", with the pure "0-surface" configuration better known as a lifting body. The space shuttle orbiter also falls in the half-and-half category (and is that a double-delta wing or tapered extensions to the lower fuselage chines?), and I am sure there must be others. In fact the Lifting body article has a section on Body lift describing a few such types. Perhaps we could add the Blackbird in there? — Cheers, Steelpillow (Talk) 14:24, 24 April 2013 (UTC)

Just taken a look at the original Flight International article by Godfrey. He embodies the muddle with vigour, variously referring to "the long chines or fuselage strakes" and "...with wing roots extended forward along the fuselage sides in the form of chines blended with the basic fuselage body" just on the first page. On the next page we find the quotes given above by Plxdesi2, with chines "acting" variously as a very low-aspect-ratio wing or as canard surfaces. He also uses the word "chine" to describe what on the Northrop YF-17 Cobra are nowadays called LERX or LEX. — Cheers, Steelpillow (Talk) 16:07, 24 April 2013 (UTC)

What about "a chine, which is a structural extension of the wing root along the sides of the vehicle, useful for providing lift at high speeds"

In SR-71 case, the chines may appear as wing extensions, but also as lift-able fuselage extensions, providing lift Aand positive pitch moment at every speed.

@Steelpillow. Here, we meet again the basic choice, visual or function classification. As "visual" knows only fuse and wings, it is unable to classify a composite (wing + lifting fuselage) aircraft. "Function" says it is a two lifting surface, nearly a canard, but this duck might be not comestible. Plxdesi2 (talk) 21:03, 24 April 2013 (UTC)

New article

I took a flyer and created a new article at Chine (aircraft). Hope you all approve. Needs more about the design issues, and a list of aircraft with chines would be cool. — Cheers, Steelpillow (Talk) 12:04, 25 April 2013 (UTC)

What in the pictures are you talking about?

It would be nice if someone that understands the terminology highlighted on the pictures which parts of the airplane are relevant. --TiagoTiago (talk) 02:51, 29 April 2013 (UTC)

I have added diagrams to my To Do list, I think that will be more generally useful than annotating copies of the photos. — Cheers, Steelpillow (Talk) 10:03, 29 April 2013 (UTC)

I had the same question; diagrams would indeed be very helpful. -- Beland (talk) 20:03, 15 July 2014 (UTC)

Any better now? — Cheers, Steelpillow (Talk) 11:09, 16 July 2014 (UTC)

Further requests

These requests were posted above the earlier discussion by Swpb (talk · contribs) without any explanation. I moved them down here to preserve the chronological order of discussion. — Cheers, Steelpillow (Talk) 16:21, 25 April 2016 (UTC)

These are not "further" requests; they are more-specific categorization of the original requests. Diagram requests should use the most specific template(s) possible. —swpb^T 18:29, 25 April 2016 (UTC)

I have already added one diagram in response to the OP. How does that fall so far short that you now feel a need to make more specific requests? If you think that more specific diagrams are needed then I would need some more specific indication of their envisaged application. There are vehicle illustrations already, so why would vehicle diagrams help and what would they need to show? Similarly, what aspects of the physics need diagramming? I can understand a need for a physics diagram if the physics is being discussed with equations given and suchlike, but that is not the case here. — Cheers, Steelpillow (Talk) 21:50, 25 April 2016 (UTC)

Move

(moved from my talk) Hi Widefox - I see you moved this article from 'Leading-edge extension' a few months back. I don't understand this move. My reading of WP:HYPHEN is that an endash should be used when the two components are in some sense equal (such as Navier–Stokes equations), but a hyphen is appropriate when the first word qualifies the second (e.g. liquid-crystal laser). Therefore it seems to me that the original title was correct, since 'leading' qualifies 'edge' here. Colonies Chris (talk) 18:52, 18 November 2018 (UTC)

I don't have an opinion, and it was a while ago. The endash matches other articles here (although one isn't hyphenated), so some consistency would be good. Widefox; talk 21:47, 18 November 2018 (UTC)

Making titles consistent without checking or knowing if they're correct in the first place just makes them consistently wrong. - BilCat (talk) 21:52, 18 November 2018 (UTC)

Attempting to fix blatant inconsistencies is good, in this case I just made an error fixing them, bad. None of that justifies bad faith assumptions of other editors not "checking" or "knowing" - how does that help? How many of these articles are still inconsistent, and who's fixing them? Widefox; talk 17:41, 19 November 2018 (UTC)

How is that a bad-faith assumption? Are you saying you knew it was incorrect when you moved it? Because what I was saying was that you didn't know. My point is to be a little more careful next time, that's all. - BilCat (talk) 18:05, 19 November 2018 (UTC)

"without checking or knowing" <- how could you possibly know that, it's an assumption, correct? I'm glad Colonies Chris caught my error, and I'm glad I brought it here. Instead of speculating on other editors, and doubling down with more fruitless speculation ("Are you" and "you didn't know"), suggest you read WP:BOLD. These articles needed improving, and still do. Widefox; talk 21:42, 19 November 2018 (UTC)

You're assuming I made a bad-faith assumption, which I did not, which makes it bad faith on your part. Just be more careful next time, or better yet, propose a move until you know the guidelines better. - BilCat (talk) 22:03, 19 November 2018 (UTC)

No assumption, it's in black and white above. The difference is I admitted my mistake. Widefox; talk 12:48, 23 November 2018 (UTC)

I propose that this article, and Leading–edge slat (currently using endash) and Leading edge cuff (currently using space), all be changed to use hyphen: Leading-edge extension, Leading-edge slat and Leading-edge cuff. I'll make the changes in a couple of days time if there are no objections. Colonies Chris (talk) 13:02, 19 November 2018 (UTC)

I self reverted: 1  Done, 2  Done, 3 left for you. We still have quotes without the hyphen in other articles, so it's still a mess. Widefox; talk 17:41, 19 November 2018 (UTC)

Long-term editor User:Ahunt created Leading edge cuff, so I'm pinging him to see if he has any objections to moving the article to Leading-edge cuff. - BilCat (talk) 18:11, 19 November 2018 (UTC)

There's also Leading edge slot. - BilCat (talk) 18:15, 19 November 2018 (UTC)

There are also a couple of references to Trailing edge flaps. Colonies Chris (talk) 10:08, 20 November 2018 (UTC)

I think we have to go with what the refs say. The first ref cited, Crane, calls this Cuff (wing leading lead components), but does have leading-edge flap with a hyphen (not an endash). - Ahunt (talk) 15:17, 20 November 2018 (UTC)