Talk:Monocoque

From Wikipedia, the free encyclopedia
Jump to: navigation, search
WikiProject Aviation / Aircraft (Rated Start-class)
WikiProject icon This article is within the scope of the Aviation WikiProject. If you would like to participate, please visit the project page, where you can join the project and see lists of open tasks and task forces. To use this banner, please see the full instructions.
Start-Class article Start  This article has been rated as Start-Class on the project's quality scale.
Checklist icon
 
Note icon
This article has been selected for use on the Aviation Portal.
 
Taskforce icon
This article is supported by the aircraft project.
WikiProject Automobiles (Rated Start-class, High-importance)
WikiProject icon This article is within the scope of WikiProject Automobiles, a collaborative effort to improve the coverage of automobiles on Wikipedia. If you would like to participate, please visit the project page, where you can join the discussion and see a list of open tasks.
Start-Class article Start  This article has been rated as Start-Class on the project's quality scale.
 High  This article has been rated as High-importance on the project's importance scale.
 

Is still really still a stub? It seems like rather fine an article.


Clean up[edit]

I have tried to improve the clarity of language in the aircraft section as per the above because although I knew the subject matter well enough and the article contains lots of good stuff I found the account a bit muddy, wordy and convoluted. I hope you see it as an improvement; it could do with some more. I hope it says the same thing, +some, with less words. Ex nihil (talk) 10:20, 22 September 2008 (UTC)


Unibody[edit]

Monocoque and Unibody are NOT the same. A monocoque vehicle uses the the outter skin as a support (.e.g. boats) a unibody uses the body framework (not the outside skin) for support. Therefore, removing the 'unibody'section and creating a seperate article from it. arfon 20:06, 12 May 2006 (UTC)

Belay my last. I'm leaving Unibody in with monocoque because I'm not sure it's not applicable now... arfon 20:16, 12 May 2006 (UTC)
You were right to begin with. Unibody isn't monocoque and it deserves its own article. This article is also collecting misplaced stuff about bicycle frames and fictional space suits. A first step to recovering it up would be to move Unibody. Question is, what to call it. Is Unibody a trade-name? Meggar 05:07, 9 September 2006 (UTC)
I previously took out the part about bicycle frames, but don't see anything about space suits. I think splitting this into two articles, each with dabs to the other, is appropriate. "Unibody" isn't a trade-name as far as I know. Even if it is, we have many articles under trade names, so that's fine. StuRat 11:18, 9 September 2006 (UTC)
I think this article needs the split. A monococque by definition is a stressed skin. You could remove all the skin panels from a modern car and it would still hold together just fine. They are only 36 thousands of an inch thick for goodness sake. I doubt that anybody has ever made a production monococque, from metal, ever.Greglocock (talk) 00:48, 6 December 2009 (UTC)
I agree - it isn't the same thing at all. Unibody redirects back to this article, perhaps the section on unibody could be moved to the redirect page, making it an article instead? - Ahunt (talk) 18:25, 6 December 2009 (UTC)
In automotive circles the terms are often interchanged. Many unibody cars have some stress skinned panels. This can include rocker panels and window frames where the exterior surface forms a portion of a load bearing beam as well as things like the floor of a car where the panel acts as a flat stress skin. However, other panels such as rear fenders are often incorporated into a unibody but don't carry any loads over their surfaces but may carry loads through the welded seams of those panels. Another criteria for unibodies is they will incorporate many other body functions into that of the frame. Things like door openings including hinge mounts and mount points for even things like speakers are all incorporated into a unibody. In the case of a car like the Fiero where the chassis had no body panels the structure is often referred to as a space frame. It should also be pointed out that few structures including most airplanes are 100% monocoque, unibody or spaceframe. A perfect monocoque structure would have no internal ribs. In general the term is used to refer to structures where a significant portion of the load is carried by the stressed skin. A unibody may have some sections such as around the engine which look more like a ladder frame while other sections are very much like a automotive spaceframe (no body panels). Finally, the spaceframe term is often defined as a purely triangulated structure where all elements are loaded only in tension or compression. However, realistically this never happens as some portion of most "spaceframes" will end up in a beam bending condition. 129.59.75.131 (talk) —Preceding undated comment added 15:45, 7 December 2009 (UTC).
So are you arguing that it belongs in this article or that it is a significantly different and complex subject to have its own article? - Ahunt (talk) 18:49, 7 December 2009 (UTC)
No, I'm not proposing any sort of move but I think it's important to point out that most structures are a blend of various types. The unibody entry previously stated that a unibody carried no loads through the surface/body panels. That isn't true. However it is true that not all the body surface will carry loads. The same edit I think also said the Feiro was a unibody. I would argue that it isn't since none of it's body panels were part of the car's space frame (perhaps the floor boards were). So I think it should be clear that when talking about auto frames (and probably air frames too) the total structure will have a mix of the various frame types. Very few would be purely one type or another. With respect to a move to a separate frame section it may not hurt to have an auto frame section simply because many people are likely to be interested in that particular subject.129.59.75.131 (talk) 19:40, 7 December 2009 (UTC)
Your edits have improved the article a lot, and since people who are looking for monocoque need to find unibody, I think the current arrangement works.That is, I no longer think it worth splitting unibody out as a separate article. Incidentally, with a unibody it is probably wrong to say the skin is unstressed, it is often stressed, but its stiffness ads little to the overall stiffness of the car. Greglocock (talk) 01:07, 8 December 2009 (UTC)
Okay let's leave it as one article then and see if it can be further improved - some more refs would be helpful in other sections. - Ahunt (talk) 03:00, 8 December 2009 (UTC)
I'm indifferent on one article or two. On one hand as it refers to automobile chassis I think it could be broken out and integrated into a single auto chassis article. On the other hand with respect to a general topic on monocoque construction I think unibody should be mentioned a long with the understanding that in automobile circles the terms seem to be used relatively interchangeably and that most auto structures would incorporate elements of both hence the reason why the terms would be interchanged. Sadly I'm not sure how many references you will find since we are talking about general terms here. For instance most higher end formula style race cars from the 1970s were considered to be monocoque chassis. However, most were not 100% monocoque. They carried loads through stress panels but they also used some tubular sections such as around the engine (and the engine its self). Also parts of the body were not stressed. Those chassis were all called monocoque but they clearly had non-monocoque parts and design elements. Basically so long as they had some monocoque element the engines called them monocoque. It was at least enough to differentiate them from "tube frame". Incidentally, the tube frame chassis also commonly used stressed skins such as the belly pan. So a tube frame wasn't 100% tubes. Furthermore, although the tube frames were often triangulated, they weren't purely triangulated. As such they can't be 100% space frames even though people would call them space frames. From a technical engineering perspective no one cares when you change from a pure monocoque stressed skin structure to a fabricated box section (unibody like) to a tube frame etc. Engineers are more interested in does the system do it's job. Some people get hung up on what "type" of frame they have when the reality is it's got elements of a number of different types.129.59.75.130 (talk) 15:24, 8 December 2009 (UTC)
I think you make some very good points there. Even in aircraft design there are virtually no monocoque airframe structures, as almost all are semi-monocoque (see the top photo in the article for a very typical example). - Ahunt (talk) 15:36, 8 December 2009 (UTC)

Boats[edit]

Surely boat hulls are relevant here. I don't have the knowledge for it, but if someone does it would be a good addition. -- cmh 15:09, 1 June 2006 (UTC)

Good idea. I added a section on boats and ships. StuRat 00:51, 1 September 2006 (UTC)

In Fiction[edit]

Article says "In contrast to real-life examples." I'm highly dubious that there are any "real-life examples" of powered suits like the ones in the anime. If no one knows of such an example, perhaps this should be reworked. Septegram 02:30, 21 August 2006 (UTC)

Even in the linked fiction articles it doesn't say anything monocoque; not that the term could in any way be applied to a suit. Removed. Meggar 05:01, 21 August 2006 (UTC)

Bicycles[edit]

Aren't all bicycles basically monocoque? The structure and shell of the bicycle have always been one and the same, right? I'd like to know whether the term monocoque is meaningful in the context of the cycling industry or just a bit of lingusitic fireworks. Don't they really mean "lugless" or "seamless"? —Preceding unsigned comment added by 38.96.187.10 (talkcontribs)

Just about no bicycles are monocoque. They are frames. The word refers to the overall structure. An egg or the fuselage of a large aircraft are monocoque; frames can't be except in advertising. Here are some examples of real ones [1][2][3] Meggar 03:33, 28 August 2007 (UTC)

This section should be removed from the article. Bicycles are definitely not monocoque, they are frames made from tubing. In fact they don't even have a skin or a shell that would allow them to have a monocoque construction. Marshallj25 (talk) 15:51, 3 March 2009 (UTC)

Clarify "subsidy"[edit]

"the Douglas DC-3, the first aircraft that could move cargo without a subsidy." What does "subsidy" mean in this context ? —Preceding unsigned comment added by 213.41.173.68 (talk) 16:25, 12 June 2008 (UTC)

DP01 pic bad example[edit]

Strictly speaking, the bits from the DP01 are not load bearing elements of the "frame". They are coverings for the monocoque parts that do indeed bear the stress. The parts shown only bear the "weight" of the aero downforce (top cover, bottom tray). Twohlford (talk) 04:52, 29 July 2008 (UTC)

Which image are you referring to? I didn't find one named DP01? - Ahunt (talk) 13:08, 29 July 2008 (UTC)
"Monocoque shell of Panoz DP01 Champ Car." The pics are of the shell, which aside from channeling air, are not load bearing members any more than the front and rear wings. A better pic would be of the DP01's tub (or the tub of any open-wheel formula car built since the late 1960's). Twohlford (talk) 02:06, 31 July 2008 (UTC)

The Lotus 25 was the first full monocoque Formula 1 car and first raced in 1962.Flanker235 (talk) 12:30, 13 September 2011 (UTC)

Laptop computer section[edit]

I added a section on laptops using unibody at the end. I hope no one minds terribly, and feel free to revert it if you wish. Tuoder (talk) 18:44, 14 October 2008 (UTC)

This section was related to the newer Macbooks being made of an aluminum shell. I removed this section because it was technically inaccurate. Laptops already used a monocoque construction and the selection of aluminum didn't change this. In fact, aluminum was already used on some laptops even before Apple publicized their use of aluminum, the other makers just painted it instead of showing the bare metal. Besides, it wasn't Apple's use of aluminum that was considered innovative, it was the way they formed it. Marshallj25 (talk) 15:32, 3 March 2009 (UTC)

Yurts and igloos not monocoques[edit]

I have deleted Igloos and Yurts as examples. An igloo is not a stressed skin, it is a very pure form of arch and works entirely in compression as do most masonry domes, which also are not monocoques. Yurts a quite clearly collapsible frames that are clad with non-structural cloth and skins, definitely not monocoques. A dome is not a monocoque if it works in compression only. A test of whether a structure is really a stressed skin is whether it maintains its integrity when compression and tensile stresses are reversed; a masonry dome turned upside down clearly falls apart, a reinforced concrete dome turned upside down might stay intact with a bit of luck and therefore we might be inclined to say it was a monocoque and it would indeed be one if the reinforcing had been designed specifically to allow inversion; in practice the reinforcing is designed to prevent buckling and allow the shell to be made thinner, structurally a concrete dome still acts as a simple arch in compression and the fact that it might hold together when in tension is purely accidental not an intended result of design so I don't believe it could be considered a monocoque. A reinforced concrete boat hull on the other hand is specifically designed to take changing compressive and tensile forces in all directions and is indeed a monocoque. Ex nihil (talk) 09:37, 20 May 2009 (UTC)

Airflow[edit]

According to the cutaway on this page, the Airflow has a very obvious internal frame. Maury Markowitz (talk) 13:49, 3 July 2010 (UTC)

Heat treating aluminium for pre-tension[edit]

Are there not examples of metal skinned aircraft where the skinning was heated before being riveted into place?

I know I have heard of this somewhere but cannot provide a reference. It's my understanding that this pre-tensions the structure and makes it more rigid.Flanker235 (talk) 12:26, 13 September 2011 (UTC)

"Sheetmetal is strongest when curved in more than two directions"[edit]

This doesn't make sense. 'Curved in more than one direction' might - implying a compound curvature. AndyTheGrump (talk) 22:51, 27 September 2011 (UTC)

The statement is unsourced so feel free to change it or remove it. Adding a ref for it would be most helpful. Ahunt (talk) 22:55, 27 September 2011 (UTC)
I just reworded what was there to make it flow better - yes it does imply a compound curvature - such as occurs when a corrugated surface is then curved perpendicular to the corrugations as was done on the wings of the Junkers and Fords (done with a row on English wheels for the Junkers - I haven't seen photos of the Ford system but wouldn't be surprised if they used stamping machines). The corrugations themselves are insufficient to impart any strength but add a second curvature and it will be rigid (within the limits of the material). I think the orginal statement compared it to a bowl. A sheet of metal can easily be curved in one direction (ie rolled up), but then bending a rolled up sheet is difficult. On wings or other areas where there is little room for compound curvature, ribs are rivetted on to create the same effect, and prevent the sheetmetal from flattening out allowing the skin to impart strength to the wing. Without either the ribs or the compound curvature, no strength exists. Not all aluminium skinned structures are prestressed or meet the definition of even semi-monococqe though.NiD.29 (talk) 02:33, 28 September 2011 (UTC)
Almost certainly true - but still lacking a source. I did a bit of Googling earlier, but couldn't really find an accessible source on the merits (if any) of compound curvature on stressed skin/monocoque structures - and thinking about it, I'm not even convinced that it is necessarily always true. Clearly, common sense suggests that a curved skin is less prone to buckling, but does compound curvature actually help? I think we'd need to find a source to back this up. AndyTheGrump (talk) 02:41, 28 September 2011 (UTC)
Some of the information in this article might be right, but at least some of it is doubtful and most of it is unsourced and has been tagged for a long time. Given the doubts I am really thinking that as per WP:V that the challenged text should all be removed and the article reduced to what is actually supported by refs. - Ahunt (talk) 11:51, 28 September 2011 (UTC)
I'd agree. Furthermore, I think that regarding monocoque construction in aircraft, there is room for expansion on non-metallic materials: we really should cover the de Havilland Mosquito as a classic example of a wooden monocoque design, and the use of composites in modern aircraft likewise needs expansion. I'd suggest that there might be room for further expansion on the topic of boat hulls too - many of these were effectively of monocoque construction long before the term was first used, from the humble coracle to the Viking Longship. AndyTheGrump (talk) 14:20, 28 September 2011 (UTC)
I agree those do need adding, but first I think all the tagged text should be removed, then the article can be built up with topics like that and refs this time! - Ahunt (talk) 15:42, 28 September 2011 (UTC)
I am digging for refs - "Composite Aircraft Manufacture and Inspection" doesn't have as much (lots on heat treatment done during the manufacturing process, no mention of applying sheets hot, tho there is of applying them cooled). Looking at Aircraft Engineering Principals...

The Mosquito duplicated previous techniques and was similar to that used by the Deperdussin (only replacing the middle layer with balsa) so isn't particularly notable - the only advantage it has is more people have heard of the Mosquito - it was already an obsolete manufacturing method by then and was only used due to a potential shortage of aluminium. The Lockheed Vega which is probably more familiar to Americans used a similar technique in the 20's. I was rather surprised there was so little in boat section and agree the Viking longship would fall under the definition since it used a minimum of internal structure, with the planks used for the skinning attached to each other rather than a frame. The birch bark canoe may do so as well - it is by no means an unusual construction technique.NiD.29 (talk) 16:37, 28 September 2011 (UTC)

User:NiD.29: Do you want some time to work on finding refs before the unref text is cleaned up then? - Ahunt (talk) 17:37, 28 September 2011 (UTC)
If you could - I am working my way through "Aircraft Structures for Engineering Students" at http://www.scribd.com/doc/45324020/Aircraft-Structures-for-Engineering-Students-Megson . No mention of compound curvatures but I suspect that is because they were only used early on - ie pre-1940 and were dispensed with when greater use of internal stiffening was found to be cheaper to manufacture and the slightly better aerodynamic form available with compound curvatures was unnecessary and of less importance than production times. Corrugated structures only get a mention as a part of an integral sandwhich structure. Due to the books age (lots of mentions of Concord) there is only a brief mention of composites.NiD.29 (talk) 19:06, 28 September 2011 (UTC)
Sure no problem - the priority is to make the article better! Perhaps it would be best if once you have exhausted what you can find then post here and let us know, or even better when you are done you could remove any text that is left unreferenced and tagged. - Ahunt (talk)
Sure, np. Hunting down all the refs may take some time. NiD.29 (talk) 01:27, 29 September 2011 (UTC)

Cars?[edit]

like the lambo aventador http://en.wikipedia.org/wiki/Aventador

why isn't there a car section? — Preceding unsigned comment added by 67.81.199.45 (talk) 01:18, 24 December 2011 (UTC)

There was, but it was tagged as having no references for years and was finally removed as per WP:V. It can e reinstated or started anew if references can be found. - Ahunt (talk) 10:55, 24 December 2011 (UTC)
"Unibody" redirects to "Monocoque#Automobiles", a non-existent section. Maybe it should just redirect to the top of the article. — QuicksilverT @ 17:06, 6 April 2012 (UTC)

Yes check.svg Done - Ahunt (talk) 17:45, 6 April 2012 (UTC)

Hilariously the picture of the Aventador shows that it isn't a monocoque at all. Greglocock (talk) 04:04, 29 March 2012 (UTC)

With cars, the common unibody design is something midway between a full-frame and a monocoque design. That is, it has a body which acts like the structural shell in a monocoque design, but then they add decorative, not-structural, sheet metal panels (or sometimes plastic) beyond that, and often a partial frame, too. There are some racing cars and experimental cars which do use a true monocoque design, though. StuRat (talk) 05:59, 29 March 2012 (UTC)
I agree. This isn't much of an article without an automobile section. - KitchM (talk) 17:35, 18 September 2012 (UTC)
As noted before information on automotive designs can be added, but as per WP:V it needs to have reliable refs cited to be included. - Ahunt (talk) 18:03, 18 September 2012 (UTC)
It seems to come up on here regularly but remarkably few car bodies, unibodies included, are monococques or even semi-monococques, and most unibodies are simply a frame over which the skin has been added, and the skin adds very little to the strength of the car. Cut away the skin areas and you still have a functional car that can be driven. The same is not true of aircraft where the skin is the main structure and significant holes must be compensated for by additional structure elsewhere. Unibody simply means there are no frame rails - such as on a heavy truck - the body provides all the strength without distinction as to whether it is the skin or a framework, and unibody should have its own article and not be redirected here at all. Agreed there are some racers that qualify but they are few and far between as most rely on tube frames or little more than a pod for the driver with frames attached for the engine and suspension - the Porsche 956 and Porsche 962 are notable exceptions and are monococque race cars.NiD.29 (talk) 19:25, 18 September 2012 (UTC)
There are plenty of monocoque road cars. Look at Europe in the '50s and '60s (some very lightweight '50s sports cars). Even though a car like the MGB does indeed have removable front wings for easy damage repair, the rear wings are an important structural component and are welded into the sill structure beneath (why it's such a pain to replace a trivially rusted wheel arch). Later cars, and the Ford Ka is perhaps the clearest example went to four very easily replaceable wings for cheap repair, but the structure at front and back is still a monocoque, more than a semi-spaceframe, even if there's another sheet of tin on the outside of it.
Also the 956 is even less of a monocoque. The rear chassis is typical for the day, with a semi-spaceframe around a stressed transaxle. Andy Dingley (talk) 20:18, 18 September 2012 (UTC)
If you were to cut all of the beams and box sections and tubes out of a Ka, leaving just sheet metal, then it would bend and break. If you were to cut half of the sheet metal away it would work just fine. It is not a monocoque. Greglocock (talk) 23:07, 18 September 2012 (UTC)
One of the problems I have come across is that outside aviation uses the term "monocoque" is used a bit loosely. That does make it a challenge to be precise in this article. - Ahunt (talk) 23:29, 18 September 2012 (UTC)
The trouble is that this article's lead is wrong. It describes a stressed skin structure, not a monocoque. They're not necessarily the same thing. Andy Dingley (talk) 00:11, 19 September 2012 (UTC)
There are no "tubes" in a Ka. If there's a "beam" or a "box section", it's made by pressing those same sheets. This doesn't mean it's not a monocoque. Andy Dingley (talk) 00:09, 19 September 2012 (UTC)
Without cutting one up I expect the A pillars, cant rails, cross car beam or suspension modules will use hydroformed tubes, and I think once you have welded up box sections and top hats you have strayed far from my definition of a monocoque. If the skin is not carrying much of the load (that doesn't mean it is unstressed, merely that it is not contributing much) then it ain't a monocoque in my book.Greglocock (talk) 00:45, 19 September 2012 (UTC)
Then I think you need to source the claim that "monocoque" implies "stressed skin". My book disagrees. Andy Dingley (talk) 11:17, 19 September 2012 (UTC)
from Cambridge aerospace dictionary...
p.605 stressed skin: Form of semi-monococque construction in which skin, nearly always metal, bears significant proportion of flight loads, and makes principal contribution to stiffness.
p.386 monococque: three dimensional form, such as fuselage, having all strength in skin and immediate underlying frames and stringers, with no interior structure or bracing. Some purists argue there must be skin only.
p.549 semi-monococque: Structure in which loads are carried part by frame/stringer combination and part by skin. Almost all modern fuselages are of this type.
The difference is that stressed skin is rarely applied as a term to wooden monococque shells, however it doesn't mean they differ in any real way. Perhaps because something built up of laminated layers is seen less a skin than a shell however StressSkin is a copyrighted term for a laminated metal shell.NiD.29 (talk) 19:00, 19 September 2012 (UTC)
I'd agree with all of that provided that we note "and immediate underlying frames and stringers," as being part of a monocoque. An aircraft doesn't have to be a Mosquito or a Valkyrie to be a monocoque.
For cars, I would extrapolate this same "immediate underlying" to include A posts and similar (and thus many press-formed cars are indeed monocoques). I would agree with Greg that hydroformed tubes would be outside this (on Ford's cheapest ever car though?). I wouldn't see transverse firewalls as outside a monocoque though, even if they're far from "immediate underlying" to the outer skin, as this is just part of a car's functional shape. Andy Dingley (talk) 19:48, 19 September 2012 (UTC)

Reboot - I just read the Merriam Webster definition reffed in the article. It explicitly defines an integral frame car as an example of a monocoque. While I don't agree with that definition, it seems to me that it DOES represent common usage. So we should include cars. grr. Greglocock (talk) 00:15, 20 September 2012 (UTC)

Rockets?[edit]

Yes, most rockets are a sort of monocoque structure, using the pressure of the fuel to hold them together, as well as using a stressed skin for inter-stage sections and engine housings. However, there are only a couple examples. Almost all space rockets are monocoque structures, not to mention that artillery rockets have long had (e.g., since the 17th century) pretty thick walls to avoid having an extra structure within them. This other article even says so: http://en.wikipedia.org/wiki/Rocket#Components If someone wants to work on this part someday, the evolution is clear: the V2 had an (I believe, but look it up) stressed skin as was state of the art for aircraft, but the fuel tanks were separate items. By the time of US manned space flight, everything was a simple tube full of fuel, to the point that wires sometimes run on the outside of the vehicle. Shoobe01 (talk) 03:15, 17 August 2013 (UTC)

I can't really think of a rocket (post-Goddard) that isn't a monocoque. However there are at least three groups within that.
  • Separate fuel tanks, within a monocoque. This is still fairly common, and it's a matter of fuel chemistry.
  • A monocoque. Not much that wouldn't be recognised by an aircraft designer of the '40s. The monocoque is sealed by dividers and also acts as the fuel tanks. Not much different to a pressurised aircraft. Relies on a compatible oxidiser chemistry (generally meaning cryogenic oxygen) and metallurgy that copes with the low temperatures.
  • Inflated structures, relying on internal pressure for strength. Atlas & Blue Streak are some of the rare examples.
If we're going to discuss rockets here, we should clarify these. Andy Dingley (talk) 10:32, 17 August 2013 (UTC)
If it is using the fuel to maintain its strength, then calling it a monocoque is a stretch since by definition monocoque indicates that the skin is the primary load bearing structure - NOT the contents. Balloons are not monocoques and yet they are effectively identical structurally to your third category. Do you have any real (non-wiki type) references supporting this useage? (ie something that supports this being industry usage and not just advertising copy)NiD.29 (talk) 03:43, 19 August 2013 (UTC)
The following quote is from a NASA history page describing Atlas D: "The sustainer section is made up of a thin wall, fully monocoque structure pressure vessel and derives its rigidity from internal pressurization." [4] Overjive (talk) 05:01, 19 August 2013 (UTC)
ThanksNiD.29 (talk) 14:28, 19 August 2013 (UTC)