Boeing 737MAX

Boeing penche pour un 737 entièrement neuf

Boeing penche toujours pour une version entièrement neuve de son monocouloir 737, mais certaines décisions restent à prendre, notamment sur le matériau qui sera utilisé et sur le lieu de fabrication de l'appareil, a déclaré jeudi un responsable de l'avionneur américain.

"Nous ne sommes pas intéressés par ce dont le marché a besoin aujourd'hui. Nous devons comprendre ce dont le marché aura besoin en 2030", a déclaré Mike Bair, responsable du programme monocouloir chez Boeing.

Boeing doit décider s'il reconstruit son 737 ou s'il se contente d'installer sur le modèle existant des réacteurs plus économiques en carburant.

Un avion remotorisé permettrait d'économiser environ 10% en en carburant et pourrait être mis sur le marché autour de 2016.

Un avion totalement neuf pourrait offrir le double d'économies en carburant et serait mis sur le marché vers 2019.

Le concurrent de Boeing, Airbus, filiale d'EADS, a opté l'an dernier pour une version remotorisée de l'A320, l'A320neo, concurrent du 737, ce qui lui a permis d'engranger des commandes considérables.

Boeing et Airbus se disputent un marché estimé à 1.700 milliards de dollars sur les 20 prochaines années.

Mike Bair a précisé que Boeing devait décider s'il suivait ou non l'exemple du 787 Dreamliner, en matériaux composites, ce qui permet d'économiser du carburant.

Le choix du matériau - composite, métal ou un mélange des deux - déterminera le lieu d'assemblage du prochain 737.

Le site actuel est proche de Seattle.

http://www.aerocontact.com/actualite_aeronautique_spatiale/ac-boeing-penche-pour-un-737-entierement-neuf-dirigeant~11597.html

Boeing officials have indicated the company will probably skip
re-engining the 737 in favor of building a new aircraft that would enter
service in 2019 or 2020

ghtsaber From United States of America, joined Jan 2005, 6544 posts, RR: 96
Reply 112, posted Thu Apr 7 2011 08:54:10 your local time (6 hours 26 minutes 43 secs ago) and read 782 times:

I'm an engine nut and I have issues with this quote in the OP:

Quoting LAXDESI (Thread starter):
Speaking in Toulouse during a briefing for journalists this week, Leahy said that engines, rather than airframe technology, are the main driver behind step-changes in fuel burn, so the pace of powerplant development will determine the timing of a viable all-new single-aisle.

Historically, it has been 50/50. A new narrow body with a CFRP wing, hi-li aluminum, more welding via advanced processes (fewer rivits), simpler subsystems... I see the airframe improving fuel burn by another 5%.

I see Boeing going with a new design.

Quoting Revelation (Reply 52):
Quote:

Mike Bair, vice president of Advanced 737 Product Development, says Boeing is working closely with CFM, Rolls-Royce and Pratt & Whitney to identify the airframer's engine options for a new jet.

"All three of them have given us what they think they can do for an engine that comes into service in [2019 or 2020], and it's better than what they could do for a [2015 or 2016 entry into service],"

Pratt could do a 5% reduction in fuel burn just with a composite high turbine. They're not ready now... for 2020 EIS...

I'm sure GE and RR would catch up too. I love the GTF. Pratt knows their lead will be short lived (RR has done some GTF engineering and I'm sure would be ready for a 2020 EIS with their own GTF).

Quoting CFBFrame (Reply 53):
GE has to have two stages, address the NG and then present a path for Boeing to get past 2020.



So does Pratt.
The issue for GE will be keeping a Boeing exclusive. When GE had an AAA bond rating and Boeing had AA-, it made sense for Boeing to borrow from GE. Now... I see competing engines being more of an advantage.

Quoting sirtoby (Reply 74):
Historically, you can get 0.5-0.75% better SFC a year - if you go to a larger fan diameter to do that, you have to calculate with more drag and more weight, so your actual fuel burn improvement is lower than that.

0.5% mission fuel burn has been the trent. Hence one needs years with 0.75% TSFC to cut 0.5% per year.
Quoting Stitch (Reply 100):
Pratt has long been talking about putting a GTF on the 737NG, so I would say that there is no such deal.

There is no such deal. The issue was a contractual exclusive for GE on the 737NG that expired in 2008.
Thus, Boeing wasn't interested in the GTF until recent A320NEO sales. So there could be a 737NG GTF...

However, Boeing was more interested in a single stage high turbine GTF. (It lowers maintenance costs dramatically over a dual stage high turbine GTF, but at a 4% fuel burn penalty.) Note: I didn't say TSFC, I mean mission fuel burn. With a composite turbine, it is possible to acheive very high pressure ratios with a single stage turbine. It would be the best of both worlds:
1. Low part count of a single stage turbine
2. Most of the pressure ration of a dual stage nickel turbine
3. Very light weight (good for short missions).

To be blunt, if Boeing goes after the same mission as the A320NEO, it would hurt both. In my humble opinion, Boeing should optimize more for a short mission. If Boeing goes for EIS prior to 2019, that means a GTF derived from the PW1000G. For a 2020 EIS,, Pratt has enough time to do a new high spool concept... Such as CMC turbine blades.

I do not know which way Boeing will go. I'm very interested to see what Boeing says at Paris...

Lightsaber

voodoo a écrit:
J'y vois aussi un gros souci :
-Comment gérer plusieurs longueurs de fuselage ?

Boeing reaffirms mid-year target for 737 decision
By Michael Gubisch

Boeing has restated its aim of announcing its plans for the 737 - whether to re-engine or to go for a completely new, clean-sheet design - by the middle of the year.

However, according to John Tracy, Boeing's chief technology officer, the decision will be guided by the availability of engineering resources, given the potential demands from a 777 update and the development of derivatives of the 787.

Whether a new single-aisle family will find more demand than an updated version of the 777 is the "big question" being discussed at the company, says Tracy.

The 777 will face a certain amount of competition once the A350-1000 enters service. Boeing is considering replacing the 777's aluminium wing with a composite structure as one option to update it, but has also contemplated a completely new design.

Meanwhile, in the narrowbody segment, pressure is mounting on Boeing to respond to the challenge posed by the Airbus A320neo, which has gathered more than 330 orders since its launch in December.

Summing up the challenge, Tracy says: "We are pretty much committed not to have two major development programmes going on simultaneously, [and] to get the right people on the right job at the right time."

The future single-aisle strategy will therefore be determined by the "firing order" of different new models. These include further development of the 777 and 787 derivatives, such as the stretched 787-9 that is due to enter service in 2013.

Tracy adds that the 777's future will be revealed "soon after" determining the strategy for the 737, indicating a decision on the large twinjet in the second half of this year.


Unlike Airbus, which maintains that "game-changing" technology for a next-generation narrowbody aircraft will not be available until around 2025-30 - particularly with regard to the propulsion system - Boeing takes a more sanguine view of the pace of technological advancement.

Tracy believes that the development of new technology would not be the main hurdle for a clean-sheet aircraft programme, he says. Unsurprisingly, Tracy dismisses Airbus's view on the apparent lack of maturity of advanced engineering. "I am a technologist, so I am never going to say that technology is going to limit us," he says.

It is not clear whether a brand-new single-aisle aircraft would follow the 787's lead and have one or both of the fuselage and wing made from composite, or whether it would stick with an all-metal construction. Tracy confirms that Boeing is looking at advanced metals, such as aluminium-lithium alloy, and composites.

Aside from achieving traditional aerospace objectives, such as lower weight, greater strength, better fatigue life characteristics - and in the case of engine components, higher temperature resistance - the construction material for a new aircraft must ensure ease and speed of manufacturing.

This is crucial for the high-rate production of single-aisle aircraft. Boeing plans to increase its monthly 737 output from the current level of 31.5 to 38 aircraft by the second quarter of 2013 and will consider taking this beyond 40 in future (just shy of the Airbus's planned rate of 44 on its A320 line).

The monthly 787 production rate, on the other hand, is to rise from the present two aircraft to two-and-a-half by mid-2010, reaching 10 aircraft in 2013.

Tracy signals that the time required for composite construction, as employed on the 787, would pose a challenge for a narrowbody jet, suggesting that a metal-based design is more likely.

"The composite manufacturing process today requires one to lay down material with some sort of machine and then put it into an autoclave to cure it. That takes a lot of time Can you get enough of those [production] machines in the right place at the right time or is some other approach that we need for a more rapid manufacture? Is the advantage we get with composites outweighed by the additional time to manufacture them?"

He adds that Boeing is investigating alternative technologies "to see if we can eliminate some of those manufacturing constraints".

Another challenge in developing a next-generation narrowbody will be to determine its optimum size. As with the 737 and A320 families, a new design will lead to a baseline model that can be stretched or shrunk for different capacity and performance demands.

However, especially with the smallest 737-600 and A318 models failing to generate significant sales, and Bombardier's Cseries entering the market at the lower capacity end, there have been questions whether the 737/A320 families straddle too wide a range. Critics suggest that a better course of action would be to develop two separate aircraft.

Tracy disagrees with that analysis, but believes that a slightly larger aircraft will be the preferred option. "I think it will be a similar pattern with a base model that covers a [capacity] range," he says. "There is a good chance that range will be shifted up a little bit."

http://www.flightglobal.com/articles/2011/04/26/355990/boeing-reaffirms-mid-year-target-for-737-decision.html

oeing's response to the A320neo is likely to be both a higher-performance 737NG ready by 2015 and an all-new aircraft, which will probably be a light twin-aisle entering service in 2019 or 2020, according to an assessment by Buckingham Research Group.

In a client report issued following Boeing Capital Corp.'s aviation finance conference this week, New York-based Buckingham said that Boeing "is considering a range of options for a new aircraft and believes the technology—propulsion, materials, avionics, etc.—will be available to support a service entry in 2019/2020" (ATW Daily News, April 19).

However, the firm said the "new aircraft should not be considered a replacement for the 737, 757 or Airbus narrowbodies … Like the 707, which first replaced turboprops with turbojets, the 747, which first introduced jumbo capacity, and the 777, which first introduced four-engine capacity with a two-engine airplane, Boeing's new aircraft will likely address a new market with new capabilities."

Interestingly, Buckingham reported that a "meaningful number of investors" still believe that Boeing will re-engine the 737NG. "Our view has consistently been that Boeing will not re-engine, but a number of investors acknowledge the possibility that Boeing might re-engine if a major 737 customer defected and ordered the A320neo," it said, noting, "Boeing may be so capacity-constrained [with orders] that it may not have the option to re-engine the 737."

It added, "Internally, Boeing appears convinced that the 737NG's projected 2016 performance is competitive with the A320neo ... The finance community and lessors are urging Boeing to wait and leap ahead with a new aircraft versus a derivative."

Buckingham also believes that Boeing may forgo bidding on the upcoming Delta Air Lines RFP for 200 A319-sized aircraft. "We think that Boeing already factors in some near-term share loss as a result of its product strategy and that it expects to regain the market share high ground with a new airplane later in the decade," it stated.