Ethiopian plane crash
Discussion
El stovey said:
Ayahuasca said:
I flew on a Max 9 last week, and will be flying on one in a couple of weeks.
The good news is that biz class has lie-flat seats so at least I will die in comfort.
Won’t they be upright still when it crashes? The good news is that biz class has lie-flat seats so at least I will die in comfort.
I envisage Ayahuasca stoop upright, strapped to their seat, saluting. Akin to a stubborn captain on a sinking ship.
alfaman said:
Comet accident was due to having square-ish windows which induced stress concentrations and propagated fatigue cracks / catastrophic failure after X loading and unloading cycles from depressurisation.
Fatigue and fast fracture material behaviour was not that well understood 70 ish years ago.
( we did the Comet disasters as a materials case study at Uni )
I'm glad you said "squarish" as they weren't exactly square - as so many people think. The corners were radiused and as a result the windows weren't a huge amount different to what you see on modern airliners. Where de Havilland went wrong is that they used extremely light gauge aluminium and omitted strengtheners in the corners of the window in order to save weight. In fact, the failure on G-ALYP was in a roof aperture for an RDF aerial rather than in a window. The failure on G-ALYU (which was tested to destruction in a water tank at Farnborough) was indeed with a passenger cabin window.Fatigue and fast fracture material behaviour was not that well understood 70 ish years ago.
( we did the Comet disasters as a materials case study at Uni )
It has to be mentioned that de Havilland had extremely limited experience in building pressurised aircraft up to the Comet. The only previous example of a pressurised aircraft they had ever built were a few one-off Vampire prototypes.
Other companies building pressurised fuselages in that time period i.e. Boeing, Douglas, Lockheed and Vickers, never experienced explosive decompression in the same way due to metal fatigue - so they obviously had a better grip, even in the 1940s, on what was required compared to de Havilland.
Starfighter said:
The 737 has an inherent problem with the wing box. Originally designed for a low bypass engine the whole aircraft sits on short undercarriage legs. Fitting the higher bypass LEAP engine means the engines are effectively part of the wing and pulled forwards. The A320 does not have this issue norr has the C series and the Comac 919.
Perhaps a stupid question, but can't they just fit longer landing gear to jack the whole thing up a bit? A Boeing 737 lift kit, if you will.David87 said:
Starfighter said:
The 737 has an inherent problem with the wing box. Originally designed for a low bypass engine the whole aircraft sits on short undercarriage legs. Fitting the higher bypass LEAP engine means the engines are effectively part of the wing and pulled forwards. The A320 does not have this issue norr has the C series and the Comac 919.
Perhaps a stupid question, but can't they just fit longer landing gear to jack the whole thing up a bit? A Boeing 737 lift kit, if you will.
Eric Mc said:
I'm glad you said "squarish" as they weren't exactly square - as so many people think. The corners were radiused and as a result the windows weren't a huge amount different to what you see on modern airliners. Where de Havilland went wrong is that they used extremely light gauge aluminium and omitted strengtheners in the corners of the window in order to save weight. In fact, the failure on G-ALYP was in a roof aperture for an RDF aerial rather than in a window. The failure on G-ALYU (which was tested to destruction in a water tank at Farnborough) was indeed with a passenger cabin window.
It has to be mentioned that de Havilland had extremely limited experience in building pressurised aircraft up to the Comet. The only previous example of a pressurised aircraft they had ever built were a few one-off Vampire prototypes.
Other companies building pressurised fuselages in that time period i.e. Boeing, Douglas, Lockheed and Vickers, never experienced explosive decompression in the same way due to metal fatigue - so they obviously had a better grip, even in the 1940s, on what was required compared to de Havilland.
think there were 3 crashes including an SAA plane.It has to be mentioned that de Havilland had extremely limited experience in building pressurised aircraft up to the Comet. The only previous example of a pressurised aircraft they had ever built were a few one-off Vampire prototypes.
Other companies building pressurised fuselages in that time period i.e. Boeing, Douglas, Lockheed and Vickers, never experienced explosive decompression in the same way due to metal fatigue - so they obviously had a better grip, even in the 1940s, on what was required compared to de Havilland.
The wiki articles cite reports that state metal fatigue / explosive decompression as the cause ... and apparently windows were changed to be more rounded after these crashes.
shame about the comet .. it was the first commercial jet liner .. and its demise probably helped and enabled the success of the 707 / demise of U.K. aviation
What Boeing need to do is stop bodging the 737.
If they are having to introduce features to mitigate the problems caused by this bodging, make sure people having to deal with it know about it and exactly how it works.
What we should be discussing is the 797 and not some 60s aircraft that keeps getting stretched and re-engined and raises up a bit and Botox.
If they are having to introduce features to mitigate the problems caused by this bodging, make sure people having to deal with it know about it and exactly how it works.
What we should be discussing is the 797 and not some 60s aircraft that keeps getting stretched and re-engined and raises up a bit and Botox.
Apparently the controversial anti stall software was installed (!) due to the Max series engines being fitted with a larger fan than on the Next Gen engines, so the engines had to be repositioned and (iirc) the landing gear is longer.
Saw this first generation 737 the other day - it looks distinctly under-endowed in the fan department.
Saw this first generation 737 the other day - it looks distinctly under-endowed in the fan department.
Ayahuasca said:
Apparently the controversial anti stall software was installed (!) due to the Max series engines being fitted with a larger fan than on the Next Gen engines, so the engines had to be repositioned and (iirc) the landing gear is longer.
I think that’s been explained at least three times now on this thread. alfaman said:
think there were 3 crashes including an SAA plane.
The wiki articles cite reports that state metal fatigue / explosive decompression as the cause ... and apparently windows were changed to be more rounded after these crashes.
shame about the comet .. it was the first commercial jet liner .. and its demise probably helped and enabled the success of the 707 / demise of U.K. aviation
Of the crashes caused by explosive decompression, it was only the wreckage retrieved from 'YP that showed where the failure originated. Not enough wreckage was recovered from the other crashes to enable the precise location of the failure to be ascertained. As I said in my previous post, the other failure which was positively identified was that on 'YU, which was tested to destruction in controlled conditions in the water tank at Farnborough - and that failed at an aerial aperture rather than a window.The wiki articles cite reports that state metal fatigue / explosive decompression as the cause ... and apparently windows were changed to be more rounded after these crashes.
shame about the comet .. it was the first commercial jet liner .. and its demise probably helped and enabled the success of the 707 / demise of U.K. aviation
I am pretty sure virtually nothing found from the Comet accidents had any bearing on the 707 or other manufacturers' jet airliners. de Havilland already knew they had skimped on the window design with the Comet 1 and the already designed Comet 2 was intended to have oval windows from the start. de Havilland's problem was the low power available from their own de Havilland Ghost engines which were fitted to teh Comet 1 so saving weight became a priority for them. The Comet 2 had Rolls Royve Avons which were more powerful and therefore weight saving was not such a priority.
Boeing had built the world's first pressurised airliner, the Boeing 307 stratoliner, in the mid 1930s. They also had produced pressurised B-29s, B-47s and 377 Stratocruisers before they started designing their 367-80/707 airliner - so they already had good experience on how to build pressurised aircraft.
Most airliners today have fairly "square" windows - but they are properly radiused at the corners and are obviously stronger structures overall compared to the Comet 1. In fact, when demonstrated at Farnborough, the prototype Comet 1 popped and banged quite a bit as the structure flexed during the manoeuvers carried out by John Cunningham. It really was a stripped down design.
Ayahuasca said:
Apparently the controversial anti stall software was installed (!) due to the Max series engines being fitted with a larger fan than on the Next Gen engines, so the engines had to be repositioned and (iirc) the landing gear is longer.
Saw this first generation 737 the other day - it looks distinctly under-endowed in the fan department.
When the engines switched from the "narrow" JT8D (as in the picture) to the CFM56 with the 300/400/500 series, the fan size meant that the engines had to be flattened at the bottom to allow the original undercarriage to be used.Saw this first generation 737 the other day - it looks distinctly under-endowed in the fan department.
The later 737-700/800/800 and Max 8 etc have taller undercarriages so the fatter engines can now have a more rounded shape.
737-400
737-800
737 Max
red_slr said:
Sounds like the CVR or FDR has been found. Wonder what state its in, I would be impressed if its survived that impact.
I suspect we might see the 737 Max grounded for a few days whilst they look at the data...
Is their resistance to real-time data transmission from a plane to (a) hub(s) or is it purely too technically challenging at this point? I suspect we might see the 737 Max grounded for a few days whilst they look at the data...
arfursleep said:
Is their resistance to real-time data transmission from a plane to (a) hub(s) or is it purely too technically challenging at this point?
There are various packages that airlines can pay for with different real time monitoring. None of them involve all the data for understanding a crash though.You might get the EICAS or fault messages for a MAX8 in real time but not continuous stuff like communication between the crew or other flight data.
It would be like VOLVO getting a message at the dealership saying my washer fluid was low or my brake light had failed but not hearing what I was saying to my kids or if I had veered into oncoming traffic.
arfursleep said:
red_slr said:
Sounds like the CVR or FDR has been found. Wonder what state its in, I would be impressed if its survived that impact.
I suspect we might see the 737 Max grounded for a few days whilst they look at the data...
Is their resistance to real-time data transmission from a plane to (a) hub(s) or is it purely too technically challenging at this point? I suspect we might see the 737 Max grounded for a few days whilst they look at the data...
red_slr said:
They actually log a *LOT* of data. I think basically every sensor on an aircraft like a Max sends something to the FDR. IIRC they have to record at least 24 hours of data. IIRC again, the A320 records something like 1500 sources of data with minimum duty cycle of 1Hz...
Yeah, assumed it was GBs of data to be transmitted but mass data transmissions are getting easier. Sure it'll happen in a few years timearfursleep said:
red_slr said:
They actually log a *LOT* of data. I think basically every sensor on an aircraft like a Max sends something to the FDR. IIRC they have to record at least 24 hours of data. IIRC again, the A320 records something like 1500 sources of data with minimum duty cycle of 1Hz...
Yeah, assumed it was GBs of data to be transmitted but mass data transmissions are getting easier. Sure it'll happen in a few years timeGassing Station | News, Politics & Economics | Top of Page | What's New | My Stuff