757 troubles. the latest news

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Dummy Pilot
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757 troubles. the latest news

Postby Dummy Pilot » Mon Jan 16, 2012 9:39 pm

Wall St Journal Article

Dozens of Continental Airlines flights to the East Coast from Europe have been forced to make unexpected stops in Canada and elsewhere to take on fuel after running into unusually strong headwinds over the Atlantic Ocean.

The stops, which have caused delays and inconvenience for thousands of passengers in recent weeks, are partly the result of a decision by United Continental Holdings Inc., the world's largest airline, to use smaller jets on a growing number of long, trans-Atlantic routes.

United's strategy works when the winds are calm, and it allows the airline to operate less expensive aircraft with fewer cabin-crew members to an array of European cities that wouldn't generate enough traffic to justify larger planes.

But by pushing its international Boeing Co. 757s to nearly the limit of their roughly 4,000-nautical-mile range, United is leaving little room for error when stiff winds increase the amount of fuel the planes' twin engines burn.

Last month, United said, its 169-seat 757s had to stop 43 times to refuel out of nearly 1,100 flights headed to the U.S. A year earlier, there were only 12 unscheduled stops on roughly the same volume of 757 flights.

In the story, you get to vote whether United/Continental should be allowed to use 757s to Europe.

BTW, the 45 minute fuel requirement they list is for Domestic operations. International Flag rules are different.

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3WE
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Re: 757 troubles. the latest news

Postby 3WE » Mon Jan 16, 2012 10:00 pm

First, a question. They said that "last year there were only 12 unscheduled 757 stops on the same volume of flights". If that's so, then what's changed would be more about the weather and / or how the plane is loaded (or they media is grossly botching its statsitics and "volume of flights" was "shorter haul" last year vs. "Westbound Trans Atlantic" this year? So what's really going on?

Now to some other factoids: There's about a 1 in 25 chance that the flight will stop for fuel (vs. maybe a 1 in 90 chance from the year before). If I'm a mindless MBA bean counter / paper pusher, I know there's much more of a 1 in 25 chance of a 2 hour flight delay due to everything that normally affects airline schedules....so I guess these fuel stops are not all that significant compared to what's already going on?

Hey, I have this great idea to cut costs...never mind what the pilots or passengers think!
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reubee
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Re: 757 troubles. the latest news

Postby reubee » Fri Jan 27, 2012 8:52 am

No wonder Vectors not posting, he's busy finding holes in the sky for these to come down in.
Image

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ocelot
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Re: 757 troubles. the latest news

Postby ocelot » Thu Feb 09, 2012 11:04 pm

So what's really going on?
Unfavorable jetstream configuration, I think.

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Re: 757 troubles. the latest news

Postby 3WE » Thu May 26, 2016 5:01 pm

An article on http://www.internet.com echoing the trend at JetPictures to arm-chair-second-guess Boeing's decision to mothball the younger high-clearance-gimme-a-fat-high-bypass-turbofan-version-semi-hershy-bar-wing of the 707 for stubbier (but not as stubby as it used to be), 'older' 737 (with even morer newerer engines and features).

http://finance.yahoo.com/news/boeing-ma ... 29028.html

Hind sight is 20:20, but maybe there was too much short term focus? The '707 cabin' always seemed to have a place.

I do tend to hate riding the dang things- nothing against the airplane itself, but they so often seemed to be the epitome of crappy seat pitch/cram another row in there configuration...efficient transport busses, not_comfortable airliners.
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Re: 757 troubles. the latest news

Postby GlennAB1 » Sun May 29, 2016 12:01 am

Anybody know how many minute ETOPS they are operating at?
you still have to find a crew willing to fly this "barely airworthy" heap
no such thing as "barely airworthy" it's either Airworthy or Not
100% incorrect Ever hear of Ferry Permit? issued for Non airworthy aircraft
LOL

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Re: 757 troubles. the latest news

Postby flyboy2548m » Wed Jun 22, 2016 8:54 pm

Anybody know how many minute ETOPS they are operating at?
Yes.
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Re: 757 troubles. the latest news

Postby Ancient Mariner » Thu Jun 23, 2016 10:09 am

Anybody know how many minute ETOPS they are operating at?
Yes.
It is comforting to know that at least pilots are aware of this.
Per

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Re: 757 troubles. the latest news

Postby 3WE » Sun Jun 26, 2016 1:50 pm

Anybody know how many minute ETOPS they are operating at?
Yes.
@#%@#!-totally-literal-asshat...

Flyboy, please tell us how many minutes of ETOPS that 757's are operating at these days.

Thanks in advance...and apologies; because, like the autobrake business, ...we...are curious.
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Re: 757 troubles. the latest news

Postby flyboy2548m » Sun Jun 26, 2016 11:56 pm

Anybody know how many minute ETOPS they are operating at?
Yes.
@#%@#!-totally-literal-asshat...

Flyboy, please tell us how many minutes of ETOPS that 757's are operating at these days.

Thanks in advance...and apologies; because, like the autobrake business, ...we...are curious.
Ask Evanie, I'm sure he has a 10-year-old Continental manual he can reference...
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3WE
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Re: 757 troubles. the latest news

Postby 3WE » Mon Jun 27, 2016 2:28 am

That is indeed an option.

I just think you have a bit more of the inside track, as well as the ability to see "both sides" of the issue.... ...as well as newer sources...
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Re: 757 troubles. the latest news

Postby GlennAB1 » Fri Jul 01, 2016 7:56 am

Anybody know how many minute ETOPS they are operating at?
Yes.
Thanks Flyboy, just curious, 'cause, when I worked at ATA we were the first and only 757 operator (at the time) certificated for XXX minutes ETOPS.
you still have to find a crew willing to fly this "barely airworthy" heap
no such thing as "barely airworthy" it's either Airworthy or Not
100% incorrect Ever hear of Ferry Permit? issued for Non airworthy aircraft
LOL

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Re: 757 troubles. the latest news

Postby flyboy2548m » Sat Jul 09, 2016 2:08 pm

Anybody know how many minute ETOPS they are operating at?
Yes.
Thanks Flyboy, just curious, 'cause, when I worked at ATA we were the first and only 757 operator (at the time) certificated for XXX minutes ETOPS.
You're welcome, always glad to help.
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ocelot
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Re: 757 troubles. the latest news

Postby ocelot » Fri Jul 29, 2016 3:51 am

An article on http://www.internet.com echoing the trend at JetPictures to arm-chair-second-guess Boeing's decision to mothball the younger high-clearance-gimme-a-fat-high-bypass-turbofan-version-semi-hershy-bar-wing of the 707 for stubbier (but not as stubby as it used to be), 'older' 737 (with even morer newerer engines and features).
I always thought of the 757 as being roughly a replacement for the 727, not so much the 707, but whatever.
http://finance.yahoo.com/news/boeing-ma ... 29028.html

Hind sight is 20:20, but maybe there was too much short term focus? The '707 cabin' always seemed to have a place.
...and I generally agree. Industry trends at the time were against planes that size, but industry trends come and go. In particular, industry trends come and go quite a bit faster than the design lifecycles of transport aircraft, so it always seemed unwise to me to cancel the 757 without planning a replacement.
I do tend to hate riding the dang things- nothing against the airplane itself, but they so often seemed to be the epitome of crappy seat pitch/cram another row in there configuration...efficient transport busses, not_comfortable airliners.
Now, perhaps, but I've always preferred them (and 727s before them) to 737s; the tube is bigger so you get more horizontal room. Also there's something subtle about the 757 arising from it being overengined that makes it feel solid and dependable.

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3WE
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Re: 757 troubles. the latest news

Postby 3WE » Sat Jul 30, 2016 1:37 am

I always thought of the 757 as being roughly a replacement for the 727, not so much the 707, but whatever.
Six seats across and engines on the wings and a nice-long fuselage (especially), and heavy-jet designation makes it a 707 replacement according to me.

But indeed, it also replaced 3 gas-guzzling JT-8D engines on a six-acrsoss fuselage and the stretch versions were getting there in length...so, yes, whatever.
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Re: 757 troubles. the latest news

Postby J » Mon Jun 26, 2017 2:47 pm

Paris Air Show: Boeing exec gives some detail on possible ‘797’ design
Another article said the plane was expected to have a 5,200 nm range - that would eliminate the need to stop for fuel when facing stronger Atlantic headwinds. Since Boeing is going to run out of 700 numbers after their next aircraft, why not revert to the well-respected 757 series and call it a 757-800?

Excerpt:
Boeing offered tantalizing new details about its proposed next new airplane at the Paris Air Show Tuesday, revealing for the first time that the fuselage of the jet unofficially dubbed the 797 will be carbon fiber plastic composite — and will not have the typical cross-section.
* * *
[A Boeing Vice President] also described the proposed 797 fuselage as having a “hybrid cross-section,” meaning having characteristics of both a single-aisle and a widebody fuselage.

Boeing has already said the jet’s passenger cabin will likely have two aisles, as do widebody jets, and Delaney reiterated Boeing’s mantra that the jet will have “widebody comfort” with “single-aisle economics.”

* * *
Some in the aviation trade press have speculated that this means Boeing must be looking at an elliptically shaped fuselage cross-section for the 797.

This could allow it to be wider though not as deep as today’s widebodies. Such a cross-section could reduce the overall size of the jet, though at the cost of cutting the available cargo space below the passenger cabin.

http://www.seattletimes.com/business/bo ... 97-design/

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Re: 757 troubles. the latest news

Postby Rabbi O'Genius » Tue Jun 27, 2017 8:10 am

Paris Air Show: Boeing exec gives some detail on possible ‘797’ design

* * *
Some in the aviation trade press have speculated that this means Boeing must be looking at an elliptically shaped fuselage cross-section for the 797.

This could allow it to be wider though not as deep as today’s widebodies. Such a cross-section could reduce the overall size of the jet, though at the cost of cutting the available cargo space below the passenger cabin.

http://www.seattletimes.com/business/bo ... 97-design/
One of the issues with any non-circular fuselage cross-section is that when you pressurize it internally it tries to become circular.
For an elliptical cross-section you would need a tensile element across the short axis of the ellipse to prevent this from happening.
I would guess that double decker planes (where the "ellipse" is oriented vertically) probably solve this problem by using the floor(s) as the tensile member(s). (Verbal?)
In the case of a horizontally oriented ellipse a vertical tensile member would help to handle the pressure-induced loads.
So maybe they're thinking of some kind of laterally split cabin with a "wall" in the middle, and a single aisle each side........

Disclaimer: I am not an Aero-engineer.
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Re: 757 troubles. the latest news

Postby Gabriel » Tue Jun 27, 2017 2:35 pm

Some in the aviation trade press have speculated that this means Boeing must be looking at an elliptically shaped fuselage cross-section for the 797.

This could allow it to be wider though not as deep as today’s widebodies. Such a cross-section could reduce the overall size of the jet, though at the cost of cutting the available cargo space below the passenger cabin.
That's not correct. An elliptical fuselage (wider than taller) with the same height of a single aisle fuselage like the 757 and the width of say a 767 will have less cargo space than a 767 but more than a 757, and of course the length will also be a factor.
One of the issues with any non-circular fuselage cross-section is that when you pressurize it internally it tries to become circular.
Correct.
For an elliptical cross-section you would need a tensile element across the short axis of the ellipse to prevent this from happening.
I would guess that double decker planes (where the "ellipse" is oriented vertically) probably solve this problem by using the floor(s) as the tensile member(s). (Verbal?)
A tensile vertical element will help, but would not fully solve the issue. In a simplified model (if we assume that no flexure solicitation exists where the left and right side meet), the left and right side will tend to to become circular segments themselves. So while the tensile vertical element will help reduce the flexure tension caused by the pressurization, it will not eliminate it.
That's why the DC-9/MD-80/90/B717 family (and also the A380), don't have a vertical elliptic shape, but a double-lobe (2 circular segments, one on top of the other) (triple for the A380) and the horizontal tensile element is exactly where both lobes meet, and that's the floor (both floors for the A380). In this case, yes, the tensile element practically eliminates all the flexure caused by these lobes trying to become circular, because they are already circular.

So maybe Boeing is thinking in a double-lobe, side to side? Or a quadruple lobe (2 lobes side to side but connected by two lobes in the top and bottom to eliminate the top and bottom connection, that would be an angle protruding "inside"the fuselage)?

This is a design that I thought myself in my times of an aeronautical engineer dreamer. It came together with a 2 - 3 - 3 - 2 abreast configuration that gives great pax comfort, with no pax having to climb over 2 other folks to get to the aisle, and with only 20% of middle seats. Until one day I realized that the airlines would quickly eliminate the middle aisle and make it 3 - 5 - 3 to gain 10% of pax capacity and converting the best seat config available in the worst one.
In the case of a horizontally oriented ellipse a vertical tensile member would help to handle the pressure-induced loads.
So maybe they're thinking of some kind of laterally split cabin with a "wall" in the middle, and a single aisle each side........
I would hate the window seat with the sight our of the window being another passenger next to me :)

Now, you don't need a wall. 2 beams at the tom and bottom of the fuselage connected by tensile rods every several feet would be enough.

And, finally, you don't NEED any of that. There are lots of pressurized planes that have non-round cross sections and don't have things crossing the fuselage to help handle the pressurization loads. You can make the fuselage structure to handle those loads by itself. Will it tend to become circular? Yes, in the same way that all the fuselages section ahead and back of the wing tend to flex down on its owns weight. And while that would add weight to the structure, composite materials help a lot with that. One of the great shapes is a rounded square, composed by 4 circular segments of big radius at the top and bottom. This gives a lot of space, and you need to reinforce only the 4 points where the 4 sections meet.

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Re: 757 troubles. the latest news

Postby Rabbi O'Genius » Tue Jun 27, 2017 4:12 pm

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Re: 757 troubles. the latest news

Postby Not_Karl » Fri Jun 30, 2017 4:12 am

Look what I found....
A buttplane! :shock: :shock: :shock:
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