5 ms·

I 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

I 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 look at why cockpit windows remain decidedly rectangular. :)

rsynnott 8y ago
> 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.
- andrewla 8y ago
  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.wikipedia.org/wiki/List_of_jet_airliners https://en.wikipedia.org/wiki/List_of_jet_airliners
  - mannykannot 8y ago
    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.
    - mcguire 8y ago
      Interesting point: the 737 was originally designed to take off from gravel runways.
  - rsynnott 8y ago
    Hrm, I thought the Sud Aviation Caravelle also lacked them, but I was wrong (though they're in an unusual place on it).
arethuza 8y ago
The Comet did go on in a military role as the Nimrod - I once saw an AEW Nimrod parked at the edge of RAF Kinloss - a staggeringly ugly beast: https://en.wikipedia.org/wiki/Hawker_Siddeley_Nimrod https://en.wikipedia.org/wiki/Hawker_Siddeley_Nimrod
- NeedMoreTea 8y ago
  Yeah but Nimrod was bloated, and positively covered with warts and radomes. I'd claim they spoilt the lines a tad. :)
  - arethuza 8y ago
    The normal Nimrod's were quite handsome beasts - used to see them a lot when I was a kid as I grew up near Kinloss.
    - detritus 8y ago
      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.
      - TheOtherHobbes 8y ago
        Concorde is still the most beautiful aircraft ever, IMO.
        howard941 8y ago
        The SR-71 would like a word https://en.wikipedia.org/wiki/Lockheed_SR-71_Blackbird https://en.wikipedia.org/wiki/Lockheed_SR-71_Blackbird
        8y ago
na85 8y ago
>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.
- FigBug 8y ago
  The radius of cockpit windows doesn't look that different than the radius on the Comet's square windows. https://upload.wikimedia.org/wikipedia/commons/2/2e/Boeing_747_cockpit_window_from_outside.jpg https://upload.wikimedia.org/wikipedia/commons/2/2e/Boeing_7... http://www.c-and-e-museum.org/marville/photos/planes/comet-62.jpg http://www.c-and-e-museum.org/marville/photos/planes/comet-6...
  - na85 8y ago
    Perhaps not, but remember that the metal fatigue phenomenon responsible for cracking in the Comet was not yet fully understood at that time. Nowadays we have a very good understanding of how metals degrade/respond to repeated load cycles and can design around it. I have not personally worked on airliner window structures but there are a number of avenues that one could take to retain the general shape of the window and still avoid structural compromise due to cracking.
- NeedMoreTea 8y ago
  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 popular view continues to believe the cause was windows with corners.
  - na85 8y ago
D_Alex 8y ago
>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-cockpit-window-set-6-windows-273427557830 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.
- na85 8y ago
  Hi, that's me you're insulting. Do you have a problem with any of the facts I presented?
  - D_Alex 8y ago
    I have a problem with every statement you made in your first reply, starting with "aerospace engineer here", which implies you are specially qualified to discuss airplane structural design. There are many disciplines in "aerospace engineering", and if you say work on instrumentation, then saying "aerospace engineer here" in this context is about as misleading as saying "circles are just squares with large radius corners" (they are also "triangles with large radius corners"). What do you actually do in our job?
    - na85 8y ago
      >What do you actually do in our job? I work in airworthiness and maintenance, so I deal with aerostructures on a daily basis. You? >about as misleading as saying "circles are just squares with large radius corners" What happens if you take a square with sides of length x, and smooth the corners down until the radius of each corner is x/2?
grkvlt 8y ago
Which, although technically correct, is still quite misleading and misses out the fact that this was done purely as a precaution, since the actual crack causing the failure did not come from a passenger window [0] but rather the ADF aerial square cutouts in the roof. These are what the photograph in the article shows, and the position is also highlighted in the diagram there. The 'square' passenger windows, as pointed out in the wiki link cited above, had similar corner radii (or smaller in some cases) to those of the Boeing 377 and Douglas DC-7 aircraft. 0. https://en.wikipedia.org/wiki/De_Havilland_Comet#Window_shape_misconception https://en.wikipedia.org/wiki/De_Havilland_Comet#Window_shap...
- NeedMoreTea 8y ago
  My intent had actually been to point that out in the first place when TFA concluded, as is often the case, it was the windows. See my brain fail comment somewhere downthread, as I only came back too late too edit the original: https://news.ycombinator.com/item?id=19143911 https://news.ycombinator.com/item?id=19143911

rsynnott 8y ago

> 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.

andrewla 8y ago
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.wikipedia.org/wiki/List_of_jet_airliners https://en.wikipedia.org/wiki/List_of_jet_airliners
- mannykannot 8y ago
  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.
  - mcguire 8y ago
    Interesting point: the 737 was originally designed to take off from gravel runways.
- rsynnott 8y ago
  Hrm, I thought the Sud Aviation Caravelle also lacked them, but I was wrong (though they're in an unusual place on it).

arethuza 8y ago

The Comet did go on in a military role as the Nimrod - I once saw an AEW Nimrod parked at the edge of RAF Kinloss - a staggeringly ugly beast: https://en.wikipedia.org/wiki/Hawker_Siddeley_Nimrod https://en.wikipedia.org/wiki/Hawker_Siddeley_Nimrod

NeedMoreTea 8y ago
Yeah but Nimrod was bloated, and positively covered with warts and radomes. I'd claim they spoilt the lines a tad. :)
- arethuza 8y ago
  The normal Nimrod's were quite handsome beasts - used to see them a lot when I was a kid as I grew up near Kinloss.
  - detritus 8y ago
    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.
    - TheOtherHobbes 8y ago
      Concorde is still the most beautiful aircraft ever, IMO.
      - howard941 8y ago
        The SR-71 would like a word https://en.wikipedia.org/wiki/Lockheed_SR-71_Blackbird https://en.wikipedia.org/wiki/Lockheed_SR-71_Blackbird
        8y ago

na85 8y ago

>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.

FigBug 8y ago
The radius of cockpit windows doesn't look that different than the radius on the Comet's square windows. https://upload.wikimedia.org/wikipedia/commons/2/2e/Boeing_747_cockpit_window_from_outside.jpg https://upload.wikimedia.org/wikipedia/commons/2/2e/Boeing_7... http://www.c-and-e-museum.org/marville/photos/planes/comet-62.jpg http://www.c-and-e-museum.org/marville/photos/planes/comet-6...
- na85 8y ago
  Perhaps not, but remember that the metal fatigue phenomenon responsible for cracking in the Comet was not yet fully understood at that time. Nowadays we have a very good understanding of how metals degrade/respond to repeated load cycles and can design around it. I have not personally worked on airliner window structures but there are a number of avenues that one could take to retain the general shape of the window and still avoid structural compromise due to cracking.
NeedMoreTea 8y ago
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 popular view continues to believe the cause was windows with corners.
- na85 8y ago

D_Alex 8y ago

>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-cockpit-window-set-6-windows-273427557830 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.

na85 8y ago
Hi, that's me you're insulting. Do you have a problem with any of the facts I presented?
- D_Alex 8y ago
  I have a problem with every statement you made in your first reply, starting with "aerospace engineer here", which implies you are specially qualified to discuss airplane structural design. There are many disciplines in "aerospace engineering", and if you say work on instrumentation, then saying "aerospace engineer here" in this context is about as misleading as saying "circles are just squares with large radius corners" (they are also "triangles with large radius corners"). What do you actually do in our job?
  - na85 8y ago
    >What do you actually do in our job? I work in airworthiness and maintenance, so I deal with aerostructures on a daily basis. You? >about as misleading as saying "circles are just squares with large radius corners" What happens if you take a square with sides of length x, and smooth the corners down until the radius of each corner is x/2?

grkvlt 8y ago

Which, although technically correct, is still quite misleading and misses out the fact that this was done purely as a precaution, since the actual crack causing the failure did not come from a passenger window [0] but rather the ADF aerial square cutouts in the roof. These are what the photograph in the article shows, and the position is also highlighted in the diagram there. The 'square' passenger windows, as pointed out in the wiki link cited above, had similar corner radii (or smaller in some cases) to those of the Boeing 377 and Douglas DC-7 aircraft. 0. https://en.wikipedia.org/wiki/De_Havilland_Comet#Window_shape_misconception https://en.wikipedia.org/wiki/De_Havilland_Comet#Window_shap...

NeedMoreTea 8y ago
My intent had actually been to point that out in the first place when TFA concluded, as is often the case, it was the windows. See my brain fail comment somewhere downthread, as I only came back too late too edit the original: https://news.ycombinator.com/item?id=19143911 https://news.ycombinator.com/item?id=19143911