This is the talk page for discussing improvements to the De Havilland Comet article. This is not a forum for general discussion of the article's subject.
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.AviationWikipedia:WikiProject AviationTemplate:WikiProject Aviationaviation articles
This article is within the scope of the Military history WikiProject. If you would like to participate, please visit the project page, where you can join the project and see a list of open tasks. To use this banner, please see the full instructions.Military historyWikipedia:WikiProject Military historyTemplate:WikiProject Military historymilitary history articles
I just made an edit mentioning why square windows are bad: stress concentration. I'd like to be a little more specific about the problem: Were the engineers unfamiliar with stress concentration, or did they know of it and underestimate it? Seems that the latter is more likely.
De Havilland did undertake fuselage pressurisation tests in their water tank and these revealed that there was a potential fatigue failure at the corner of the cabin window that could lead to a complete failure of the pressure cabin. Their report, issued in 1953, recommended no further remedial cation needed as the pressure applied in the water tank were far in excess if what would be encountered in normal service.
(De Havilland Comet p67...K Darling.. Crowood Press 2004) Didn't help that the roof mounted ADF panel was also square.. Lynx707 (talk) 11:29, 28 July 2008 (UTC)[reply]
The Comet's pressure cabin was designed according to the best design practices of the time, and was in fact, designed to far exceed the-then CAA strength requirements, something like twice that which was considered necessary. Commercial aircraft pressure cabins had never undergone comprehensive stress measurements, or at least, had been designed based on estimates of predicted loads, rather than measured loads, and worldwide all designs were based on these or similar stress calculations. After the accidents when a test Comet was flown with the cabin fitted-out with a considerable number of strain gauges, it was only then discovered how much the stress concentrations differed in certain areas (such as the corners of the cabin windows) from that which had been predicted, and which all previous pressurised cabins had been based-on. In short, the theory had been in error (or rather, incomplete), and it was only the accidents to the Comet that showed this up. The point about using a thinner-gauge of cabin skinning than on previous pressurised cabin airliners is that, by what was known about fatigue and pressure cabins at the time, it SHOULD have still been perfectly safe.
The square windows had been specified by the customers, as passengers preferred them, and if you look at contemporary pressurised piston-engined airliners, e.g., Boeing Stratocruiser, Douglas DC-6 C-97 Stratofreighter pictured as the Stratocruiser article only has images of the later round-windowed aircraft you can see they had square windows too. They were only changed to rounded ones after the Comet crashes. (Avro had originally designed the Tudor with circular windows but the customer (BOAC) made them change them, which was one of the reasons the Tudor was so late and over-budget, as they had to change all the ones already built. Avro then had to change them all back to circular windows after the Comet crashes).
Before the Comet they had never been a problem, as the piston-engined airliners flew at lower altitudes, and so the pressure differentials were also lower, and fatigue had never been such a factor. In effect, the Comet's cabin expanded-and-contracted when it climbed-and-descended to a much greater extent than in previous aircraft (not helped by the thinner-gauge fuselage skinning), which, unexpectedly, greatly increased the fatigue effect. The water pressure test that de Havilland had subjected the cabin-to during the designing of the aircraft had been carried out on only a section of the cabin, and unfortunately the plugs at either end (that sealed off the cabin test section to make it watertight) had been contributing more than had been allowed-for in the ultimate strength and rigidity of the test section. So the test wasn't actually representative of the complete fuselage. All this wasn't known until after the accidents, and it's hard to see how, with the state of the knowledge they then had, it could have been predicted, as the Comet was at the time the most comprehensively tested airliner then-built.
It was bad luck, that's all, and de Havilland passed-on all the conclusions about the new factors that had to be taken into account in safe pressure cabin design that now make cabin failure almost unknown in today's airliners. As someone said, if it hadn't happened to de Havilland, it would almost certainly have happened to someone else. —Preceding unsigned comment added by 213.40.254.27 (talk) 21:40, 2 October 2009 (UTC)[reply]
A missing link? The article says the windows were supposed to be rivetted and glued, but in the end, only rivetted. This seems a crucial ommission, and I would expect the report to at least mention responsibility for this failure. It might be a good idea to try and source the responsibility for that fatal decision. (It sounds like a typical management thing; it's okay just rivetted; we need to go faster; so screw the second requirement, let's just get on with it, that sort of rationalization.) Still, I for one would like to know who made that choice, and whether it was the final mistake in a chain of mistakes.24.81.25.127 (talk) 17:09, 5 August 2010 (UTC)[reply]
Lack of "feel" in controls
I've just added one requested citation; the one remaining is for The Comet 1 and 1A have been criticised for a lack of "feel" in their controls. I find this a bit dubious – there's a quote from test pilot John Cunningham (in Nicholas Faith's Black Box) stating that the Comet "responded to the controls in the best way De Havilland aircraft usually did". So unless someone comes up with a citation for the 'lack of feel' claim shortly, I suggest we remove it. Cheers, Ian Rose01:05, 27 July 2007 (UTC)[reply]
Actually, it might be a good idea to add the Cunningham quite as well, for balance. It seems some didn't like it, and some did? Or perhaps Cunningham's quote is meant to be ironic? Maury (talk) 12:21, 30 December 2007 (UTC)[reply]
Apologies for not responding earlier - yep, will add Cunningham's quote. I think he meant it seriously, the full quote has more words about the plane's impact on aviation, which is probably worth including. Cheers, Ian Rose (talk) 20:30, 5 January 2008 (UTC)[reply]
IIRC, the 'lack of feel' was an inherent problem of early powered flight controls, and was the reason artificial feel (Q-Feel) was developed. It was used on the Saunders-Roe Princess, and varied the 'stiffness' of the controls as felt by the pilot through the control column & rudder pedals, with airspeed, more effort being required as airspeed increased. The Comet was earlier than the Princess and so initially lacked the artificial feel units. —Preceding unsigned comment added by 213.40.217.163 (talk) 11:18, 22 March 2009 (UTC)[reply]
(undent) Well that's a possibility, but at that point what is the value of the statement? One could come up with some sort of contrived set of specification that would make any aircraft the first at something. The F-15 was the first to carry conformal fuel tanks -- but is that what we think of when we think of the F-15? Is pressurization what made the Comet interesting? I still suggest the statement simply be removed. Maury (talk) 17:02, 5 January 2008 (UTC)[reply]
Agree with Maury. Obviously it's the first commercial jet transport to be pressurised, because it was first commercial jet transport and it was, well, pressurised! However I'd simply mention that it was pressurised, not turn it into a contrived 'first'. Cheers, Ian Rose (talk) 20:22, 5 January 2008 (UTC)[reply]
Concur. It was jets that made her, not pressurization; that was a consequence, not a cause. Just to confuse the ish, tho, can it be said she was first to demand pressurization, to take best advantage of her powerplants? (I don't recall if the C.102 was pressurized; I'd guess so, ditto.) Trekphiler (talk) 14:35 & 14:37, 6 January 2008 (UTC)[reply]
Comet wings
The Comet wing was a design which has been in near-continuous civil and military service for over half a century, an achievement matched only by the Boeing 707/C-137/E-3.
What is the purpose of this sentence? As written, this is OR, and basically meaningless. The DC-3's wings have been in service for much longer, as have their airframes in most cases. I could be wrong, but are there some Comet wings out there flying around without fuselages?? Seriously, it's not unusual for wings to be in service as long as the airframe, tho some aircraft have been re-winged during there service life. Basically, this is a peacock sentence, and irrelevant. It seems to be a round-a-bout way of say that although the original fuselage design was crap, the wing was a much better design. Huh? - BillCJ (talk) 20:14, 30 December 2007 (UTC)[reply]
It is trying to focus on the wing design vs actual hardware. But that's does not change your point. Basically it says the wing was a good design. I think the sentence is OK without the "an achievement ..." part though. -Fnlayson (talk) 21:26, 30 December 2007 (UTC)[reply]
Agree with the removal of the sentence - I am not sure the fact the basic wing design has been used for a long time is really an achievement - just the luck of history nothing to do with the design. It was only used on two aircraft one happened to be the Nimrod which has been around for a long time because the Military dont like spending money on new equipment. Was the Comet 4 wing exactly the same as the Comet 1?, was the Nimrod wing centre-section re-designed for the Spey? My is point is that good design does not equal longevity. There is an original 1909 Bleriot still flying I presume the wing design on that was an excellent achivement! MilborneOne (talk) 21:40, 30 December 2007 (UTC)[reply]
Fair points. The sentence itself doesn't actually say it is a good design, just states longevity. Which may not mean much as you said. Yea, just leave it out. In general a good design doesn't mean the best. A good design could be overdesigned, i.e. heavier than needed. -Fnlayson (talk) 21:54, 30 December 2007 (UTC)[reply]
If there is a reliable source describing the wing design as an achievement (or as anything else notable), with a description of its longevity, and what made it notable, I'd have no problem with something like that being included in the text. - BillCJ (talk) 21:56, 30 December 2007 (UTC)[reply]
Tupolev
My source is the red star book #35. RGDS Alexmcfire
"Perminates" is not a word I'm familiar with, so I'm not sure what you're getting at, but yes the novel foreshadows the Comet disasters in certain respects. Nevil Shute was an aircraft designer before WWII, and - contrary to popular perception - the issue of fatigue in airframes and concern over new materials and techniques existed long before Comet. FiggyBee (talk) 09:55, 17 April 2008 (UTC)[reply]
In fact, that's the reason many 1930's metal airliners were highly polished; they found that polishing the metal reduced crack growth that led to fatigue. Improved alloys and "structural paints" have greatly improved the airframes in this regard. Maury (talk) 20:42, 12 May 2008 (UTC)[reply]
Flying Comet?
Under the Comet 4 heading, the article states: "There is a campaign to return Canopus to flight, with the current goal to have her in the air by the 50th anniversary of the first regular transatlantic jet service, 4 October 2008." I don't have information on this, but it obviously needs an update.--Lester02:24, 23 December 2008 (UTC)[reply]
I added Pan American Airlines to the list of proposed American Operators. PanAm president Juan Trippe ordered three Comet 3s. He canceled his order after the two 1954 crashes.
"early Comet models suffered from catastrophic metal fatigue, causing a string of well-publicised accidents.
"
Although there were accidents atributable possibly to over rotation and over powered controls which needed modification, surely actual 'catastrophic strctural failure' only caused two crashes of the Comet 1? Can two crashes be described as a string? 88.107.85.15 (talk) 08:30, 14 May 2009 (UTC)[reply]
Possibly a bit of literary licence at work. How about:
"early Comet models suffered from catastrophic metal fatigue, resulting in well-publicised accidents." FWiW Bzuk (talk) 10:46, 14 May 2009 (UTC).[reply]
No Highway (2)
In the 'See also' section, is a mention of the movie No Highway in the Sky, which was based on a novel called No Highway by author Nevil Shute. In writing the book, Shute was attempting to warn the public about the dangers of metal fatigue in commercial airliners. The mainstream media often draws the connection between this movie and the De Havilland Comet, even though the movie used a fictional aircraft called the 'Rutland Reindeer' (which never existed). The movie was released a few years before the first Comet crash due to metal fatigue. Anyway, No Highway in the Sky deserves to remain in the 'See also' list. I ask that people stop deleting it.--Lester03:19, 1 September 2009 (UTC)[reply]
There is no direct connection to the DH Comet and the only way that this submission can be justified is to have verifiable, authoritative references that state there is a connection. BTW, after being reverted twice in succession, the onus is on the original contributor to bolster a case for retention. FWiW Bzuk (talk) 04:57, 1 September 2009 (UTC).[reply]
Here is a concession since the original submitter is intent on putting this information in, despite not having verifiable sources nor locating it logically in the text. Here it is (after some preliminary research): In a section on Popular culture,
No Highway in the Sky aka: No Highway (1951), a movie which foreshadowed the Comet crashes, depicted a fictional aircraft which had structural flaws due to metal fatigue. The film was based on Nevil Shute's earlier book, No Highway (1948).[1]FWiW Bzuk (talk) 15:18, 2 September 2009 (UTC).[reply]
Cant agee that we need any mention as the film has no relation to the Comet just a coincidence. Perhaps a better place would be Fatigue (material). Submitter insistance does not overcome reliable reference directly linking the book to the unbuilt Comet. MilborneOne (talk) 18:03, 2 September 2009 (UTC)[reply]
In doing a cursory research on the book and film, I found a direct reference to Shute and the later Comet crashes. After publication, the book was considered an important work that foretold the problems of structural engineering that would be experienced by jet-powered aircraft. Check the source and you will find that the more recent book reviews 1999 and 1997 pointedly draw the reader to the connection with the Comet crashes as well as the recent film review of 2009. See this quote: ""No Highway in the Sky" is the film based on Nevil Shute's famous novel "No Highway", which predicted the effects of metal fatigue in modern aircraft and foretold the tragedy that befell British Comets several years later." FwiW Bzuk (talk) 18:13, 2 September 2009 (UTC).[reply]
I'm with Milborne on this, especially on the word "unbuilt". Hindsight is wonderful. Can you point us exactly to these reviews, Bzuk? The only ref in the list is to the Nevil Shute Norway Foundation. The two book reviews of No Highway both have identified authors but do not contain any mention of the Comet. There is an anonymous filmography and this is the source of the above quote. So do we have anything citable? I must be looking in the wrong place. I've added a couple of words and a cn.TSRL (talk) 10:11, 7 February 2010 (UTC)[reply]
There has been no response suggesting any specific connection of this book/film with the Comet. The fatigue failure in the Comet, related to fuselage apertures and pressurisation, was quite different from the fictional Reindeer's tailplane failure. As MilborneOne said, the right place to mention these interesting works is under under Metal fatigue, and that has been done. It is clearly not an appearance (of the Comet, notable or not) in the media unless the Comet appears in it. It does not appear in the book, which was published before the Comet flew. I don't have a copy of the film handy, but if the Comet is not in it surely the section should go. Let's give it a few days, and if there is no support, delete it.TSRL (talk) 23:23, 26 February 2010 (UTC)[reply]
The No Highway reference should remain. Nobody is saying that the aircraft in No Highway is the same aircraft as the Comet. It's an analogy. The point is that Shute was closely connected to De Havilland and used the book as an analogy to draw attention to the dangers of metal fatigue which were poorly appreciated at that time. Possibly some rewording of the article was appropriate, but total deletion of that section is not appropriate, as the mainstream media generally drew the connection between the book and the Comet.--Lester21:43, 8 March 2010 (UTC)[reply]
Can someone make a case for the connection between the Comet and this 1960 film? As I understand it from the Cone of Silence synopsis, this film was about an aircraft that had take-off problems, flying through hedges. Apart from being a jet (they filmed an Avro Ashton), how does this relate to the Comet which de-pressurised catastrophically at high altitude. I can see that the Ashton might appear in this regard in Aircraft in Fiction, not by implication but as a player; but the Comet? Why not the 707 or DC-8?
If the Silence is unbroken, I'll associate the film and the Ashton.TSRL (talk) 22:25, 6 February 2010 (UTC)[reply]
It may be connected with the problem that two Comets had, one failed to get airborne in Italy and one at Calcutta. See under Early accidents and incidents. MilborneOne (talk) 21:50, 8 February 2010 (UTC)[reply]
Case made.TSRL (talk) 22:36, 8 February 2010 (UTC) ...pause for thought... Since the Comet does not appear in the film or the book, it cannot (in my view) be a notable appearance,and as the Comet events and their relationship to the novel and film are related elsewhere in the article, I've removed the Cone of Silence from Notable appearances. The Avro Ashton page will link to Cone of Silence in Aircraft in Fiction shortly. Could do with a ref, though.TSRL (talk) 17:44, 9 February 2010 (UTC)[reply]
.svg)
