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The De Havilland Comet: A Pioneer with a Fatal Flaw

Soumis
 
The story of the design of the de Havilland Comet, the first jet-powered airliner. Why the two high-profile crashes occurred, and how this was fixed. (aeroxplorer.com) Plus d'info...

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captainfourbars
captainfourbars 12
It is amazing how a tiny country like the UK created the world's first turbo-prop airliner (Vickers Viscount) and then the world's first jetliner - the Comet. Also the first in the world with supersonic passenger flight (in partnership with the French), public broadcast television, the World Wide Web and many other items taken for granted today.

The Comet's problems being solved, it went on flying passengers around the globe in its 4-Series. Also, until very recently its military version, as the submarine-catching Nimrod. Those early failures served as an invaluable learning tool for today's airline-building giants. Like they say, as the most modern fighters can trace their roots to the Nazi-thrashing Spitfire, so too the venerable Comet was the father of all today's most sophisticated jetliners.
ColinSeftel
Colin Seftel 7
In 1950, the UK had a population of 50 million, about a third of the USA's population at that time and the most populous European country. Hardly a "tiny country"! Also, at that time the UK led the world in the development of jet engines, so it's not surprising that the first commercial jet transport came from Britain. GE developed the first American jet engine with British help, provided during WW2. See https://www.ge.com/news/reports/history-in-the-making-how-ge-turned-america-from-laggard-to-leader-in-jet-engine-design
SkyAware123
SkyAware123 5
tiny ? The sun would never set on the british empire. tiny my ass.
ianedge
Ian Edge 6
We may be a tiny country but have always had excellent designers, engineers and a workforce as good as any .All we lacked was commercial acumen and investment
DTBMF
Daniel Gless 1
Lucas Refrigeration....why the English drink warm beer.
LeftlySC
Stephen Leftly 3
Lucas - the prince of darkness! I worked for a time at Great King Street, Birmingham for Lucas... a horribly run company.

However the actual reason people in England drink "warm" beer (if ~55F is considered "warm") is that most British beers are actually "ales" which use a different yeast than most "largers" that form the basis of most American beers. Largers are brewed at 48F to 58F ales are brewed at 60F to 78F.

Largers at 50F are not fun...in contrast a British bitter at 50F is really good. Most IPAs served in the US today are served way too cold and are almost tasteless at around 35F.....

All of course nothing to do with metal fatigue.......

It was my understanding that the reason the fault was not found was due to the fact the the airframe used for fatigue testing had previously been used for over pressurization tests and due to that the stress intensity factor had been reduced due to yield, which blunted the tip of the cracks.
bbabis
bbabis 5
I don’t know what the max diff on an early comet was but you have to wonder what were they thinking with thin skin and punch rivets. You would also think that the water tank test would have been done before certification. Oh well, we still live and learn or die and learn today.
E1craZ4life
Edward Bardes 6
In fairness, there were many things about aviation that weren't widely understood when the Comet was first developed.
ianedge
Ian Edge 4
8000ft.They decided to use their own engines which weren't as powerful as the RR Avons etc so they used thinner shins in parts to save weight..A commercial decision like Boing with their Max.
The next post investigation had thicker skins oval windows, and RR Avon engines .
I think the cracks first spread from the ADF Ariel aperture at the top of the fuselage .
hmausfr
Henry Miller 3
The British taxpayer paid for the water tank test.
captainfourbars
It was the tradition back then to have square windows, the corners of which were demonstrated in the tests to be a built-in weakness in pressurised aircraft, leading to the failures and the 'explosive' decompression catastrophes. That was when aircraft windows switched to oval shaped.
ColinSeftel
Colin Seftel 2
As mentioned in the article, the fatigue cracks were not caused by square windows alone. The root cause was the use of punched, rather than drilled rivet holes. The Comet prototypes, which had drilled holes, flew for years without incident.
nasdisco
Chris B 5
As a kid, I flew in one.......
dan01ster
Dan Drimmie 4
Another often overlooked fact...the Royal Canadian Air Force (RCAF) operated the world's first regularly scheduled passenger jet service (on the route from Canada to Germany), beating all civilian commercial airlines to the punch.
dan01ster
Dan Drimmie 3
forgot to mention that the RCAF used the Comet on the world's first scheduled jet service on North Atlantic.
dan01ster
Dan Drimmie 3
Also of note... Canada was beaten by the British Comet by only 13 days, a significant achievement for a country that was about 1/5 the size of G.B. The AVRO Jetliner nearly went to production, with Howard Hughes offering to build them under license. More here...
"The Avro Canada C102 Jetliner was a Canadian prototype medium-range turbojet-powered jet airliner built by Avro Canada in 1949. It was beaten to the air by only 13 days by the de Havilland Comet, thereby becoming the second jet airliner in the world. The name "Jetliner" was chosen as a shortening of the term "jet airliner", a term which is still in popular usage. The aircraft was considered suitable for busy routes along the US eastern seaboard and garnered intense interest, notably from Howard Hughes who even offered to start production under license. However continued delays in Avro Canada's all-weather interceptor project, the CF-100 Canuck, led to an order to stop working on the project in 1951, with the prototype Jetliner later cut up for scrap."
Archer3
David Grimm 1
Interesting article. I wasn't aware the first crash was a problem on takeoff.
I flew in a United Arab (probably now Egyptian Airlines or is it Egypt Air? Comet IV. My only ride.
Frankfurt to Cairo. 1966.
Bandrunner
Bandrunner 1
The other design flaw was the oval air intakes to the engines. At take-off angle there was insufficient airflow going through them. Later rectified.
KevinLamprecht
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