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keesje
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Airbus : Extensive Testing A30X Configurations

Mon Feb 09, 2009 11:32 am

A nice summary on aviationweek.com on the ongoing studies for A320/737 successors.

http://www.aviationweek.com/aw/gener...e=Airbus%20Refines%20A30X%20Design

Engine choices and related aircraft configuration / EIS timelines seems still to be the open questions. Or EIS as driver for possible engine technology. A chicken or egg debate.

I think the airframers won't let even an economic downturn distract them from getting a good starting position in this x000 aircraft replacement segment.

To be or not to be committing to an open rotor engine seems to be the question.



To be or not to be, that is the question;
Whether 'tis nobler in the mind to suffer
The slings and arrows of outrageous fortune,
Or to take arms against a sea of troubles


Source: William Shakespeare's Hamlet
 
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frigatebird
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RE: Airbus : Extensive Testing A30X Configurations

Mon Feb 09, 2009 12:17 pm

Very interesting article, thank you very much for sharing.

Personally, as an aviation enthusiast, I'm very glad to read that a completely different looking design is now a very serious option: forward swept wings, open-rotor engines positioned on the empennage: unlike the 787 or A350 Joe Public can see something radically new on the airports or in the air. The same kind of change from propeller engined aircraft to jet engined aircraft, or from swept wings to the delta wing of Concorde.

I cannot wait until this all becomes reality! I'm sure Boeing will not be far behind, interesting times ahead  bigthumbsup 

Quoting Keesje (Thread starter):
Engine choices and related aircraft configuration / EIS timelines seems still to be the open questions. Or EIS as driver for possible engine technology. A chicken or egg debate.

As long as both the current A320 and 737 backlogs are in the thousands, A and B will not hurry, or wait until engine makers set a definite date for launch of an open rotor design, which seems to become future at least for narrowbodies. In the upcoming years I believe production will exceed sales however, and with dwindling backlogs this may trigger both manufacturers to finally make the big step and launch a new design. I believe this will still be about 5 years away, with EIS around 2020 or so.
 
parapente
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RE: Airbus : Extensive Testing A30X Configurations

Mon Feb 09, 2009 3:10 pm

I second that -well found. You may have seen the bits and pieces I found recently on new BWB research.https://www.airliners.net/aviation-forums/general_aviation/read.main/4305021/

Whilst a slightly different topic one article did say that the next step (for Boeing) was to build a 737 sized prototype. Now this is NOT to say that they see their replacement as being a hybrid BWB -but it might be. How fantastic would it be id the 2 manufacturers came out with 2 completely different routes (winner takes all). The illustration looks very close to Airbus' biggest narrowbody customer Easyjet's design -coincidence??

Also I noted in the other thread that there was a (first ever?) small illustration of an hybrid BWB with twin rear mounted open rotor engines.

Again on their own these little snippits mean nothing. But I do wonder if this fight of the next decade is not going to mean that both sides will need to go for absolute max efficiency -over every other dynamic -as it is the key one $$$$$$$. (and CO2). So I would lean towards an open rotor solution for both now.
 
MCIGuy
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RE: Airbus : Extensive Testing A30X Configurations

Mon Feb 09, 2009 3:20 pm

LEAP-X is supposed to be ready by 2016 so I think we'll see new narrow-bodies sooner than later.
The open rotor design is a novel one, but these novel designs never make it into reality. My prediction: The next generation of narrow-body airliners will be twin turbofans with underwing engines.  Smile
 
birdbrainz
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RE: Airbus : Extensive Testing A30X Configurations

Mon Feb 09, 2009 3:21 pm



Quoting Frigatebird (Reply 1):
Personally, as an aviation enthusiast, I'm very glad to read that a completely different looking design is now a very serious option: forward swept wings, open-rotor engines positioned on the empennage: unlike the 787 or A350 Joe Public can see something radically new on the airports or in the air. The same kind of change from propeller engined aircraft to jet engined aircraft, or from swept wings to the delta wing of Concorde.

I'll certainly agree with that from an emotional and aesthetic standpoint, but I also think it's good to remember why things are that shape. It reminds me a lot of the classic upright bicycle. For nearly a century, people have tried to improve upon the diamond frame. I've even owned two recumbent bikes. At the end of the day, the "classic" diamond shaped frame wins out in most cases.

The same is true of the modern two-engined aircraft like the 787 or A350. This design wasn't arrived at by accident.

As for that design, I'm concerned about two things: maintaining/checking the engines, and what happens to the tail section if those fan blades become unattached.

However, I agree with you that shapes have gotten a little boring lately.
 
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Stitch
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RE: Airbus : Extensive Testing A30X Configurations

Mon Feb 09, 2009 3:23 pm

Quoting Parapente (Reply 2):
But I do wonder if this fight of the next decade is not going to mean that both sides will need to go for absolute max efficiency -over every other dynamic -as it is the key one $$$$$$$. (and CO2). So I would lean towards an open rotor solution for both now.

Do not discount noise. Airport communities around the world are demanding quieter planes and as I understand it, open rotor engines are exceptionally loud, hence designs that mount them up and away from the fuselage and try to surround them with control surfaces to help act as baffles.

[Edited 2009-02-09 07:24:41]
 
MCIGuy
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RE: Airbus : Extensive Testing A30X Configurations

Mon Feb 09, 2009 3:30 pm



Quoting Stitch (Reply 5):
as I understand it, open rotor engines are exceptionally loud

Me too, think C-130.
 
gsosbee
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RE: Airbus : Extensive Testing A30X Configurations

Mon Feb 09, 2009 3:36 pm

Interesting and thanks for posting. The upcoming decade or two should be interesting. The illustration above is interesting; however the CG issues with weight and thrust above the center axis of the airplane will need to be solved before this particular concept can go much further. This can be assisted with computer controlled surfaces, but that adds weight and complexity to the airplane.
 
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pylon101
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RE: Airbus : Extensive Testing A30X Configurations

Mon Feb 09, 2009 3:36 pm

A possibility that A & B might go different routes is excluded IMHO.
Neither manufacturer is interested even in theoretical risk to lose the biggest part of the business - if counterpart's choice of design prevails.

At some point either the design choice is obvious, or A & B decide together which way to go.
 
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par13del
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RE: Airbus : Extensive Testing A30X Configurations

Mon Feb 09, 2009 3:45 pm



Quoting Pylon101 (Reply 8):
At some point either the design choice is obvious, or A & B decide together which way to go.

That trend of thought did not prevent A from going side stick or type rating across a range of frames, or using one fuselage type across various models, or B deciding that a large twin - B-777 was the way to go rather than 4 engines, why would they stop now?
If either side sees where some idea will give them an advantage they will jump on it, only us fan boys believe that both OEM's want to see the other in business, that's political speak either B or A would love if all a/c flown belonged to them.
Presently the technology does not exits to give either side a quantum leap ahead in the A320/B737 market, if one could get two aisles efficiently on a/c that side someone would produce it, harsh reality is that within this market segment, the improvement has to come from engine technology, the rest - composites, avionics etc. are marginal at best and easily matched.
 
scouseflyer
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RE: Airbus : Extensive Testing A30X Configurations

Mon Feb 09, 2009 3:48 pm

Did anyone see the MD80 fly in the 1980s with the Open-roter prototype engine and can you remember how noisy it was?
 
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Stitch
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RE: Airbus : Extensive Testing A30X Configurations

Mon Feb 09, 2009 4:02 pm

The type of control input was a function of design aesthetic. In some ways so was the move from physical physical cables to electronic wires in control surfaces (I understand they allow more nuanced control inputs, but the actual actuators remain mostly the same whether they're commanded by cables or wires).

As to the 777 being a twin, it still has it's engines slung under the wings and twins had been performing long-range operations for over a decade.

And Airbus and Boeing use common fuselage forms because it means tooling costs remain low.

Jet engines on commercial airliners in the "modern" era (the past half decade) have generally been hung under the wings because that is the easiest way to maintain them and it offers the most flexibility in terms of scaling thanks to CoB and other physical properties. You can only hang so large/heavy an engine off the aft of a plane, which is why you either need to use more then two (727, VC-10, etc.) or you can only grow so large. Witness the latest generation of regional jets, who have moved from aft-mounted engines to underwing-mounted.

Open rotor engines mounted above the fuselage and surrounded by control-surface baffles are going to be far more difficult to maintain due to having to use "cherry-pickers" and other specialized equipment to reach them. You'll also have less room to work about them because of clearances between the engines and the control surfaces (which in itself could cause issues with airflow over said surfaces and affect their performance).

I certainly can't rule them out, but I would not be surprised if all these tests and design studies are working against the concept and not promoting it.
 
texl1649
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RE: Airbus : Extensive Testing A30X Configurations

Mon Feb 09, 2009 4:06 pm

Aren't noise cancellation systems getting nearly viable for near-airport use, in addition to cabin systems?
 
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PITingres
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RE: Airbus : Extensive Testing A30X Configurations

Mon Feb 09, 2009 4:46 pm



Quoting Texl1649 (Reply 12):
Aren't noise cancellation systems getting nearly viable for near-airport use, in addition to cabin systems?

I read at least one paper based on the original flight tests that stated that open rotor was going to have serious noise problems along the entire flight path, not just landing and taking off.

I wish the open rotor people all the best in their noise suppression efforts, but my bet is on open rotor for commercial air transport never making it past another flight test article, if even that far. I hope I'm being pessimistic.
 
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par13del
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RE: Airbus : Extensive Testing A30X Configurations

Mon Feb 09, 2009 5:01 pm

Well during WWII Kurt Tank tried a cowl to streamline the radial engines on the FW-190, this is an open rotor design, how about some form of covering, I know technically you are getting into a jet engine design, I simply mean is there any way to cover the rotors rather than open. If that could be done, they could be moved under the wings.

Just a thought from a non-technical engineer type.
 
DfwRevolution
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RE: Airbus : Extensive Testing A30X Configurations

Mon Feb 09, 2009 5:02 pm



Quoting PITIngres (Reply 13):
I read at least one paper based on the original flight tests that stated that open rotor was going to have serious noise problems along the entire flight path, not just landing and taking off.

At cruise altitude, an open rotor won't have trouble with ground noise over its flight path but there is the issue of cabin noise. One of the big technical issues with the open rotors flown in the 1980s were their vibration levels. This led to a very noisy cabin environment and posed fatigue problems for the engine pylons and rear empennage.

Constructing an airframe of a stiffer material like carbon fiber could help mitigate some of the vibration issues as could active vibration canceling systems.

Quoting PITIngres (Reply 13):
I wish the open rotor people all the best in their noise suppression efforts, but my bet is on open rotor for commercial air transport never making it past another flight test article, if even that far. I hope I'm being pessimistic.

I don't see the open rotor entering widespread commercial service because it's clear that more "conventional" turbofans have not reached a plateau. An all-new narrowbody using a conventional turbofan could still achieve a 15-20% reduction in SFC by the end of next decade without compromising on noise, maintenance, or cruise speed.
 
ArabAirX
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RE: Airbus : Extensive Testing A30X Configurations

Mon Feb 09, 2009 5:49 pm



Quoting DfwRevolution (Reply 15):
I don't see the open rotor entering widespread commercial service because it's clear that more "conventional" turbofans have not reached a plateau.

I share your view on that otehrwise the likes of PW would not be doing the GTF or CFM looking at the LEAP-X engines.

On the other hand, the chances of a smaller diameter open-rotor could make its way onto a bizjet...
 
Oykie
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RE: Airbus : Extensive Testing A30X Configurations

Mon Feb 09, 2009 6:00 pm



Quoting Keesje (Thread starter):
I think the air framers won't let even an economic downturn distract them from getting a good starting position in this x000 aircraft replacement segment.

I believe this downturn might accelerate a replacement need. When orders did keep coming in, Boeing and Airbus said. Hey. Let's not rush things. Remember the saying. "Don't fix it if it ain't broke". When Boeing was by far the largest manufacturer they only kept upgrading their portfolio. Airbus tried get a bigger share and kept on developing. After 9/11 and the orders went dry Boeing started being creative and launched the 787. I doubt that Boeing would have launched that plane if it time had been better. They might have continued on the SSC as well as the 767-400ERX and 767-300ERX. But as the economy dried up, the setting became survival of the fittest. The A332 won that battle. Now on the 737/A320 replacements the stakes are higher. Both have a pretty competitive product range. The low price, high rate of production low operating cost that gets lower for each year makes it difficult for new entrants such as the C-series or Embraer competitor. So what will be the optimum replacement? I am sure that as orders dry up, the replacement will come sooner, rather than later. But perhaps as a mid life upgrade rather than an entire new airframe? Both airframes are pretty optimized. But perhaps they should sacrifice commonality to make each model even more competitive? I mean the A318, 736 should loose some weight. As should the A319 and the 73G. The 738/739ER and the A320/321 should get a higher MTOW so they could take more payload on transcontinental route. I believe that would be the safest bet right now.

Quoting Frigatebird (Reply 1):
In the upcoming years I believe production will exceed sales however, and with dwindling backlogs this may trigger both manufacturers to finally make the big step and launch a new design.

 checkmark I believe that you are right

Quoting MCIGuy (Reply 3):
LEAP-X is supposed to be ready by 2016 so I think we'll see new narrow-bodies sooner than later.

A mid-life update combined with LEAP-X engines or GTF might be the safest bet for the manufacturers right now.

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