757 troubles. the latest news

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Verbal
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Re: 757 troubles. the latest news

Postby Verbal » Fri Feb 01, 2019 12:31 am

What?
Yes.
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Re: 757 troubles. the latest news

Postby ocelot » Tue Feb 12, 2019 11:13 pm


The other one would be to resurrect the 757. Maybe stretch the fuselage a bit, improve the wings, the systems and the cockpit (an the interior) to make it part of the 787 / 777-X "family". And of course put new engines that are 20% more fuel efficient than those in the original 757, and enter the weight saving cycle again. Yes, the 757 production line and most of the tooling doesn't exist anymore. But the design is there, so it would be again a matter of a design improvement with reduced development cost, time and risk, and a good part of the flight testing and structural testing done, and a type certificate already existing to add a variant rather than a new type certificate.
By the time you rearrange the wing in line with the latest company secrets, tinker with the fuselage size, deploy composites rearranging the weights of everything, and merge the 787's electrical system, this isn't really different from doing a "new" design. It's unlikely you'd be able to skip much of the testing. Things in aerospace are rarely/never fully clean-slate anyway; that's why planes from the same manufacturer tend to have family resemblances.

As for shortening the 787, all else being equal a long and narrow plane is substantially preferable to a short and fat one.

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Re: 757 troubles. the latest news

Postby Gabriel » Tue Feb 12, 2019 11:29 pm


The other one would be to resurrect the 757. Maybe stretch the fuselage a bit, improve the wings, the systems and the cockpit (an the interior) to make it part of the 787 / 777-X "family". And of course put new engines that are 20% more fuel efficient than those in the original 757, and enter the weight saving cycle again. Yes, the 757 production line and most of the tooling doesn't exist anymore. But the design is there, so it would be again a matter of a design improvement with reduced development cost, time and risk, and a good part of the flight testing and structural testing done, and a type certificate already existing to add a variant rather than a new type certificate.
By the time you rearrange the wing in line with the latest company secrets, tinker with the fuselage size, deploy composites rearranging the weights of everything, and merge the 787's electrical system, this isn't really different from doing a "new" design. It's unlikely you'd be able to skip much of the testing. Things in aerospace are rarely/never fully clean-slate anyway; that's why planes from the same manufacturer tend to have family resemblances.
2 things:
1- I was not thinking of such a dramatic change. Think of the 757-MAX or 757-X. Basically new engines (that would be the most important change), improved cockpit (in line with the 787 which is already in line with the 777-X and 737-MAX), winglets should be easy, and perhaps some improvement to some system. Not a new wing or make it an "electric" plane like the 787. The type of improvements made to the 777 to make it an "-X", or even less than that.
2- The question is whether you certify the plane as a variant under the 757 type certificate rather than a brand new type certificate. That alone saves a lot of time and cost.

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Re: 757 troubles. the latest news

Postby Verbal » Tue Feb 12, 2019 11:52 pm

The 757 is dead and buried. Please don't dance on its grave.
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Re: 757 troubles. the latest news

Postby Gabriel » Wed Feb 13, 2019 12:34 am

As for shortening the 787, all else being equal a long and narrow plane is substantially preferable to a short and fat one.
So many variables are involved in changing from long and narrow to short and fat that that I don't even know what you have in mind when you say "all else being equal".

Given equal volumes, long and narrow requires more skin that short and fat. More skin means more friction drag. Pressure drag will be better but if the design is reasonable to allow for pressure recovery with no separation the difference should be negligible. Also if you design a modern laminar flow fuselage nose, the fraction of the fuselage under laminar flow would be greater in a fat and short. All in all, from an aerodynamic point of view, I don;t expect a lot of difference and, if anything, fat and short would be slightly better.

More skin also means more weight, other things being equal. But other things are not equal. Skin needs to be thicker the bigger the diameter, to withstand pressurization. But you need less structure to resist flexing (in both directions) and torsion, since that structure will be further away from the center giving it better moment of inertia (the Resistance of Materials moment of inertia, not the Mechanics one).

Now I started with "equal volume". But there is more to that. You don't put people in a volumetric fashion but in a floor plan fashion (unless you use more than 1 pax deck). The question is how many seats you can put in the DIAMETER, not in the cross section. I.e, how many abreast. And while twice the diameter is twice the room to put seats, it is 4 times the volume of the cylinder and 4 times the skin. Then, since you need at least an aisle, not all the diameter can be used for seats. In this regard, the single aisle 3-3 configuration is unbeatable. You are occupying with seats e of the 7 spaces available abreast (the 7th is the aisle). The 2nd most efficient one (diametrical speaking) is 10 abreast with 10 out of 12 spaces occupied. Yet, for some reason Boeing went twin aisle with the 767, with the almost-worst-in-class (from the diameter occupancy point of view) of 2-3-2. That is, they added 2 more spaces to the 3-3 configuration and half of them went to aisle. (only worse one is 1-2 as seen is some ERJs).
So a twin aisle has a lot more volume per pax. While this can be seen as an inefficiency, it also provides room for overhead bins, fuel, paid cargo and, why not, comfort (more ample view).

Boeing has not said much about a potential new 757 replacement, but they did say that they were thinking of a hybrid fuselage, which everybody understood as a non-circular twin-aisle section. So definitively they are thinking in short and fat rather than long and narrow.

Finally, the smallest 787 currently in production, the 787-8, has a capacity of 242 pax in a typical 2 class config. The biggest 757, the 300, has 243 in a typical 2 class config. Although, fair to acknowledge, due to the different missions, the "typical" config are different. The 787, flying much longer flights, has more business and fewer economy compared to the 757. But we are already in the ballpark. It's not like you need a huge shortening of the fuselage to match the 757 seating. I have little doubts that a 787 fuselage would make for a fantastic 757-like plane.

The question is, however, what to do with all the extra capability of the 787 that costs money in the shape of initial cost and fuel consumption. The 787-8 takes about the same number of pax than the 757-300 but more than twice the distance, and weights twice as much too, with engines that are way ore powerful than what a MOM (middle-of-market, i.e 767) plane would need.
You would probably want to reduce the wings (especially the span to make it fit in a 757/767 gate, perhaps adding winglets) and the fuel capacity, this will reduce the weight which can then be used to lighten the structure put smaller engines, which will in turn further reduce the weight and hence the drag and hence the fuel consumption. How to make a smaller 787 weight what a 757 does is the real challenge for this option.

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Re: 757 troubles. the latest news

Postby Gabriel » Wed Feb 13, 2019 12:35 am

The 757 is dead and buried. Please don't dance on its grave.
Yes, it is dead and buried. Resurrecting it would be almost the opposite than dancing on its grave.

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Re: 757 troubles. the latest news

Postby Verbal » Wed Feb 13, 2019 1:07 am

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Re: 757 troubles. the latest news

Postby Not_Karl » Wed Feb 13, 2019 1:38 am

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I see Boeing is already advancing with the weight-reduction phase...
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Re: 757 troubles. the latest news

Postby elaw » Wed Feb 13, 2019 5:40 pm

I thought it was an engineering testbed to figure out how to create larger lavatories.
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Re: 757 troubles. the latest news

Postby Not_Karl » Wed Feb 13, 2019 9:04 pm

I thought it was an engineering testbed to figure out how to create even smaller lavatories.
Fixed.
What I really like is that revolutionary anti-tailstrike landing gear :clap: :clap: :clap:
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Re: 757 troubles. the latest news

Postby 3WE » Sun Feb 17, 2019 10:45 pm

The 757 is dead and buried. Please don't dance on its grave.
Noted.

But do not forget that A-319/20/21 are flying in its place.
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Re: 757 troubles. the latest news

Postby ocelot » Mon Feb 25, 2019 1:55 am

So many variables are involved in changing from long and narrow to short and fat that that I don't even know what you have in mind when you say "all else being equal".
The effects I had in mind were (a) the dependence of drag on frontal area, and (b) short fat objects have relatively poor longitudinal stability and require more damping (active or passive) which cuts into efficiency. I think of these as the typical dominant factors, but this may be a bad habit left over from models, or even other domains.

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Re: 757 troubles. the latest news

Postby Gabriel » Mon Feb 25, 2019 3:21 am

So many variables are involved in changing from long and narrow to short and fat that that I don't even know what you have in mind when you say "all else being equal".
The effects I had in mind were (a) the dependence of drag on frontal area, and (b) short fat objects have relatively poor longitudinal stability and require more damping (active or passive) which cuts into efficiency. I think of these as the typical dominant factors, but this may be a bad habit left over from models, or even other domains.
Unlike cars, where you have a huge separation of the flow in the rear, in airplanes you have very little if any flow separation in the fuselage. Under this circumstances, most of the drag is not pressure drag but viscous drag (plain friction), and the frontal area is not a huge factor at all, on the contrary, it is quite negligible, and the drag will depend mostly on the wet area, which may or may be not greater in one design vs the other.

Regarding the longitudinal stability, yes, shorter planes need a bigger tail which has more surface which creates more drag.

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Re: 757 troubles. the latest news

Postby ocelot » Sun Mar 17, 2019 7:45 am

Unlike cars, where you have a huge separation of the flow in the rear, in airplanes you have very little if any flow separation in the fuselage. Under this circumstances, most of the drag is not pressure drag but viscous drag (plain friction), and the frontal area is not a huge factor at all, on the contrary, it is quite negligible, and the drag will depend mostly on the wet area, which may or may be not greater in one design vs the other.
Ok, I sit corrected...

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Re: 757 troubles. the latest news

Postby J » Tue Jul 16, 2019 4:42 pm

Let's take time out to reflect on a good aircraft - even if dead and buried according to Verbal.

The 10 Longest Scheduled Routes Operated by Boeing’s 757

1.UA EWR-ARN 3,930 Nautical Miles

United takes the winner as the longest 757 flight operator. The Chicago-based carrier flies daily between its hub in Newark and Stockholm in Sweden with an internationally configured Boeing 757-200. The flight time is blocked at 8 hours and 10 minutes on the way out and 8 hours and 50 minutes on the way back.

* * *

10.AA MIA-BSB 3,599 Miles

Back in November, American announced that its longest Boeing 757 route between Miami and Brasilia would operate using the Boeing 737 MAX 8 as of May 4, attributing the change to poor capacity performance on the route. However, with the global MAX grounding, the route continued to be operated by American’s internationally configured Boeing 757-200s with 176 seats in a two class configuration. Business Class is made up by 16 B/E Aerospace Diamond seats.

https://airlinegeeks.com/2019/07/15/lon ... gle-aisle/

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Re: 757 troubles. the latest news

Postby Gabriel » Tue Jul 16, 2019 8:58 pm

Let's take time out to reflect on a good aircraft - even if dead and buried according to Verbal.

The 10 Longest Scheduled Routes Operated by Boeing’s 757

1.UA EWR-ARN 3,930 Nautical Miles

United takes the winner as the longest 757 flight operator. The Chicago-based carrier flies daily between its hub in Newark and Stockholm in Sweden with an internationally configured Boeing 757-200. The flight time is blocked at 8 hours and 10 minutes on the way out and 8 hours and 50 minutes on the way back.

* * *

10.AA MIA-BSB 3,599 Miles

Back in November, American announced that its longest Boeing 757 route between Miami and Brasilia would operate using the Boeing 737 MAX 8 as of May 4, attributing the change to poor capacity performance on the route. However, with the global MAX grounding, the route continued to be operated by American’s internationally configured Boeing 757-200s with 176 seats in a two class configuration. Business Class is made up by 16 B/E Aerospace Diamond seats.

https://airlinegeeks.com/2019/07/15/lon ... gle-aisle/
I flew a (now defunct) LAPA 757 from Buenos Aires to Punta Cana and back in 1999. The greatest circle distance is 3728 miles (the real route is a bit longer).

Curiously, Copa flies from Panama City (PTY) to Buenos Aires with a 737-800. The distance is a bit shorter (3312 miles) and they take 160 pax, but if they wanted to take 176 they could either fly single class or use the -900ER instead.

And with the Max line, you can fly 153 pax 4400 miles (Max-7) or 204 pax 3800 miles (always in 2 class).
If you need more pax or more distance you need to move to the 787 which starts from 242 pax (-7) or from 7400 miles (-10)

So the gap is really if you want to fly 200-250 pax some 5000 to 6000 miles. That is not exactly what the 757 covered, but back then the 737 could not take so may paxs nor fly so far as it does today. This is the new MoM gap (middle-of-market).

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Re: 757 troubles. the latest news

Postby J » Wed Nov 18, 2020 1:43 pm

FAA clears Boeing 737 Max to fly again after 20-month grounding

The Federal Aviation Administration on Wednesday cleared the Boeing’s 737 Max to fly again after a nearly two-year ban, a turning point in a protracted crisis for the aircraft giant stemming from two crashes of its top-selling plane that killed 346 people.

“The design and certification of this aircraft included an unprecedented level of collaborative and independent reviews by aviation authorities around the world,” the FAA said in a statement. “Those regulators have indicated that Boeing’s design changes, together with the changes to crew procedures and training enhancements, will give them the confidence to validate the aircraft as safe to fly in their respective countries and regions.”

Boeing shares were up 6% in premarket trading after the FAA ungrounded the jets.

The end of the 20-month flight ban gives Boeing the chance to start handing over the roughly 450 Max jetliners it has produced but has been unable to deliver to customers after regulators ordered airlines to stop flying them in March 2019.

Boeing has a backlog of more than 3,000 other Boeing 737 Max planes, a number that has declined as the lengthy grounding coupled with the coronavirus pandemic prompted customers to call off hundreds of orders.

https://www.cnbc.com/2020/11/18/boeing- ... ashes.html

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Re: 757 troubles. the latest news

Postby J » Wed Nov 18, 2020 2:47 pm

A brain lock had me post the above in the 757 thread rather than the 737. Please forgive this human factors mistake.

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Re: 757 troubles. the latest news

Postby Verbal » Fri Mar 19, 2021 11:18 pm

Glory days of Trump's gold-plated 757 seem far away as plane sits idle at a sleepy airport
https://www.cnn.com/2021/03/19/politics ... index.html

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Re: 757 troubles. the latest news

Postby flyboy2548m » Sat Mar 20, 2021 8:56 pm

Glory days of Trump's gold-plated 757 seem far away as plane sits idle at a sleepy airport
https://www.cnn.com/2021/03/19/politics ... index.html

Image
He also has access to a G650.
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Re: 757 troubles. the latest news

Postby Gabriel » Sun Mar 21, 2021 3:58 am

https://www.airway1.com/tango-01-argent ... fly-again/

Previous president "4 million $ to keep this plane flying, plus 8000 $/h to fly it, and if we need to go to North America or Europe we need a fuel stop. I better fly the airlines and we reduce the size of the teams flying. We don't need a presidential plane, the country has other priorities"

Current president: "We need to fly and take a lot of people with us. Returning this plane to service is 4 million $ and let's add aux fuel tanks and winglets for another 4 millions so we don't need to stop for fuel, and the total of 8 millions is still way cheaper than the Boeing BBJ that we would buy to replace it, and yes, the cost per hour of the BBJ is 15% less but we would need 30 years to recover the difference in investment with the savings per hour. Plus, the BBJ has 17 seats less and, did I mention that we want to take a lot of people with us?"

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Re: 757 troubles. the latest news

Postby Not_Karl » Sun Mar 21, 2021 6:02 am

https://www.airway1.com/tango-01-argent ... fly-again/

Previous president "4 million $ to keep this plane flying, plus 8000 $/h to fly it, and if we need to go to North America or Europe we need a fuel stop. I better fly the airlines and we reduce the size of the teams flying. We don't need a presidential plane, the country has other priorities"

Current president: "We need to fly and take a lot of people with us. Returning this plane to service is 4 million $ and let's add aux fuel tanks and winglets for another 4 millions so we don't need to stop for fuel, and the total of 8 millions is still way cheaper than the Boeing BBJ that we would buy to replace it, and yes, the cost per hour of the BBJ is 15% less but we would need 30 years to recover the difference in investment with the savings per hour. Plus, the BBJ has 17 seats less and, did I mention that we want to take a lot of people with us?"
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Re: 757 troubles. the latest news

Postby flyboy2548m » Mon Mar 22, 2021 8:07 pm

https://www.airway1.com/tango-01-argent ... fly-again/

Previous president "4 million $ to keep this plane flying, plus 8000 $/h to fly it, and if we need to go to North America or Europe we need a fuel stop. I better fly the airlines and we reduce the size of the teams flying. We don't need a presidential plane, the country has other priorities"

Current president: "We need to fly and take a lot of people with us. Returning this plane to service is 4 million $ and let's add aux fuel tanks and winglets for another 4 millions so we don't need to stop for fuel, and the total of 8 millions is still way cheaper than the Boeing BBJ that we would buy to replace it, and yes, the cost per hour of the BBJ is 15% less but we would need 30 years to recover the difference in investment with the savings per hour. Plus, the BBJ has 17 seats less and, did I mention that we want to take a lot of people with us?"
If the airplane is otherwise solid, I, too, would refurbish the 75 rather than find a BBJ.
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Re: 757 troubles. the latest news

Postby Gabriel » Tue Mar 23, 2021 12:44 am

https://www.airway1.com/tango-01-argent ... fly-again/

Previous president "4 million $ to keep this plane flying, plus 8000 $/h to fly it, and if we need to go to North America or Europe we need a fuel stop. I better fly the airlines and we reduce the size of the teams flying. We don't need a presidential plane, the country has other priorities"

Current president: "We need to fly and take a lot of people with us. Returning this plane to service is 4 million $ and let's add aux fuel tanks and winglets for another 4 millions so we don't need to stop for fuel, and the total of 8 millions is still way cheaper than the Boeing BBJ that we would buy to replace it, and yes, the cost per hour of the BBJ is 15% less but we would need 30 years to recover the difference in investment with the savings per hour. Plus, the BBJ has 17 seats less and, did I mention that we want to take a lot of people with us?"
If the airplane is otherwise solid, I, too, would refurbish the 75 rather than find a BBJ.
I agree, if it has to be between these 2 options. But what the previous president said is we can get away with neither, fly commercial in first / business class and in smaller teams. And that's what they did. With this 3rd option, I don't know how the math works.

Oh and yes, the airplane is solid, it was first under a "low utilization program" and then under a Boeing preservation program, the APU, hydraulics, PACs etc are turned on / cycled every month, lubrication is performed, etc.... It is a low hours airframe, but you know that the MX has to be done after so many cycles or so much time, whatever happens first, so a lot of the inspections (including several C inspections, which are staggered as C1, C2, C3 etc...) are overdue now due to time, they need to bring the plane back to working condition for a ferry flight to a maintenance facility somewhere in the world since in Arg there is no company certified for 757 service.

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Re: 757 troubles. the latest news

Postby flyboy2548m » Tue Mar 23, 2021 3:50 pm

It is a low hours airframe, but you know that the MX has to be done after so many cycles or so much time, whatever happens first, so a lot of the inspections (including several C inspections, which are staggered as C1, C2, C3 etc...) are overdue now due to time, they need to bring the plane back to working condition for a ferry flight to a maintenance facility somewhere in the world since in Arg there is no company certified for 757 service.
I imagine it will go to Delta's heavy maintenance facility in ATL, especially since it's been there before.
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