Such a shame Nimrod is no longer flying. But it replacement(Rivet Joint) makes a mockery of regulations introduced because of Nimrod. Basically the MAA would like more information on adhering to regulations at time of production, they'd like an idea of when things start to fail. The RAF may not have even fully qualified for to fly because they were built in the 60s! They don't want the same mistakes like Nimrod because of fatigue
The de Havilland Comet
31–40 of 54 posts
Re: The de Havilland Comet
#32Earlier quoted context omitted.
>Yet none ever wonder or look at why cockpit windows remain decidedly rectangular. :) Aerospace engineer here. It's not the shape of the window but the radius of the corner. A circle is just a square with large-radius corners, really, and it's the sharp corner that causes stress concentrations. If you look closely at modern jet liner cockpit windows you'll see they are in fact still rounded at the corners.
I'm sure my brain had another sentence that never made it to keyboard when I was writing that, as I've given completely the wrong impression, opposite to intended. No idea what I was thinking. :) Comet windows did have rounded corners, as seen in the wreckage photo, similar to the 707's and others. The cause was stress at rivet holes and lack of strength in those areas. After strengthening it had oval windows. The po…
I believe you're correct, but they did also find that the magnitude of stress concentrations around the windows were much higher than design analysis predicted.
Re: The de Havilland Comet
#33I still think the Comet manages to look more futuristic than other civil planes. Something about the look of those engines in the wing roots with not a nacelle in sight. Such a shame it turned out to be doomed due to being first and the now well known metal fatigue story. The article, as with everything Comet related, ends with noting that lesson is why airliners now have very rounded windows. Yet none ever wonder or…
>Yet none ever wonder or look at why cockpit windows remain decidedly rectangular. :)
Don't listen to the "aerospace engineer" that answered you.
The reason why cockpit windows are so angular is of course for visibility. They are mounted in a heavy load-bearing frame. Structural efficiency is sacrificed for a better view.
I tried to find a nice picture for you, but the best I could find is this https://polybull.com/product/genuine-boeing-747-400-full-coc...
These in turn are mounted on another heavy frame that attaches to the main bulkheads. You can see the angles are quite sharp, certainly no more rounded than the Comet windows were. But, once stress concentration and metal fatigue was understood, appropriate allowances could be made.
Conversely, for passengers, the view is compromised for better structural efficiency.
Re: The de Havilland Comet
#34Earlier quoted context omitted.
> Something about the look of those engines in the wing roots with not a nacelle in sight. Quite a few early jetliners lacked normal nacelles.
Can you give some examples? I'm curious as I also find the de Havilland Comet design to be quite remarkable for this compared to modern jetliners, and this is the first time I'm encountering the design. EDIT: I found this wikipedia page [1] and clicked around, and the only jetliners I found without nacelles are the Tupolev ones -- the Tu-334, Tu-104, Tu-110, Tu-124 -- and the Tuplev supersonic Tu-144. [1] https://en.…
The Avro Canada Jetliner is another example, though it never went into production, and if you are including the Tu-144 then the Concorde belongs as well, and the original 737 also had its engines mounted directly under the wing, without pylons. While it is not quite the same, I think all trijets except the DC10/MD80 had the third engine buried in the tail.
There were many military designs, such as the British V-bombers, with engines mounted in or directly on the wing, without pylons.
Re: The de Havilland Comet
#35Earlier quoted context omitted.
Can you give some examples? I'm curious as I also find the de Havilland Comet design to be quite remarkable for this compared to modern jetliners, and this is the first time I'm encountering the design. EDIT: I found this wikipedia page [1] and clicked around, and the only jetliners I found without nacelles are the Tupolev ones -- the Tu-334, Tu-104, Tu-110, Tu-124 -- and the Tuplev supersonic Tu-144. [1] https://en.…
The Avro Canada Jetliner is another example, though it never went into production, and if you are including the Tu-144 then the Concorde belongs as well, and the original 737 also had its engines mounted directly under the wing, without pylons. While it is not quite the same, I think all trijets except the DC10/MD80 had the third engine buried in the tail. There were many military designs, such as the British V-bombe…
Interesting point: the 737 was originally designed to take off from gravel runways.
Re: The de Havilland Comet
#36When I first saw the headline I was thinking it was this Komet :-) https://en.wikipedia.org/wiki/Messerschmitt_Me_163_Komet
Also an interesting aircraft.
Re: The de Havilland Comet
#37Earlier quoted context omitted.
They were an amazing example of a legacy system being maintained far beyond any reasonable expectation of life at gradually increasing cost, to a great extent because nobody could agree on a replacement and the one-off cost of a replacement was always a bit more than the endless "maintenance" and "refurbishment". If I remember rightly the refurbishment project hit the problem that, because the original planes were ha…
The B-52 program is slated to have a 95 year operational time span. Partly as an experiment in maintaining old aircraft.
Yes, but Boeing built 744 of the things, and only 78 (or fewer) are still in USAF service (I believe NASA has one …). So the ones being upgraded are from a late production batch (the B-52H) and presumably by that point Boeing had standardized things properly.
Comet production ran to 114 aircraft in four major versions, of significantly different size and engine configuration (they started with a 36 seater, and ended up with 119 passengers in a charter-variant of the Comet 4C). No individual model of Comet got anywhere close to a triple-digit production run.
Oh, and 26 hull loss accidents!
Re: The de Havilland Comet
#38Re: The de Havilland Comet
#39Earlier quoted context omitted.
My school was right next to a runway (as in a couple of hundred metres at most) — whenever a Nimrod was taking off, class had to stop and wait for it to do its thing as there was simply no competing with it on volume. Loud buggers! As with a lot of British war jets from the post War decades, there was something quite beautiful — almost organic — in their lines.
I remember seeing a Vulcan bomber doing aerobatics over our wee Scottish village - quite a site and the noise was incredible.
Back in the 70's, or perhaps early 80's when I was a kid, my family were on our usual yearly summer camping holiday on the west coast of Scotland. One day whilst out for a drive around Skye a Vulcan came up from behind us and flew very low over our family car (you could almost count the rivets) and then did a nose up into the sky. It was quite bloody amazing, it was loud and there was a thick black plume of exhaust as it powered up and away from us. Tremendous machines.
Re: The de Havilland Comet
#40Earlier quoted context omitted.
> Something about the look of those engines in the wing roots with not a nacelle in sight. Quite a few early jetliners lacked normal nacelles.
Can you give some examples? I'm curious as I also find the de Havilland Comet design to be quite remarkable for this compared to modern jetliners, and this is the first time I'm encountering the design. EDIT: I found this wikipedia page [1] and clicked around, and the only jetliners I found without nacelles are the Tupolev ones -- the Tu-334, Tu-104, Tu-110, Tu-124 -- and the Tuplev supersonic Tu-144. [1] https://en.…
Hrm, I thought the Sud Aviation Caravelle also lacked them, but I was wrong (though they're in an unusual place on it).