Airbus A30X Blended Body-engine Concept

keesje · Mon Sep 13, 2010 10:16 am

Airbus will likely (very) soon announce the A320 NEO for which the PW GTF seems a likely candidate. This aircraft will form the backbone of NB sales for the next 10 years.

The A320 will be succeeded by a new narrowbody when substantial technological advances have been made and the market situation demands so. Last year a few possible configurations for the Aircraft dubbed A30X have been released.

http://www.flightglobal.com/blogs/fl...airbus-global-market-forecast.html

The two concepts with engine above the aft fuselage have been studied in various european research programs during the last decade. The third concpet shows a more radical redesign. It seems this concept is newer, Airbus used this summer for discussing future designs, produced additional models and graphics.

Although these are concepts only, I think a few interesting design directions become visible.

Wings: long slim clean, laminar flow wings most OEMS are looking after.

Engines: no open rotors but a more conventional ducted variant (although we do not know what’s inside). This concpet would indicate the industry isn't confident open rotor like promoted by RR will become feasible..

Size: it seems this aircraft is not a easily sizeable as e.g. the A318-A321 series. This could indicate Airbus still thinks the A320 will be replaced by 2 narrowbodies, a bigger and smaller one.

This pictures shows a more recent concept. It seems they messed up the windows / doors to hide the scale. I would not be suprized as this is a concept might be a twin aisle.

http://blog.flightstory.net/1529/images-airbus-concept-plane/

parapente · Mon Sep 13, 2010 3:23 pm

Thanks for above.It will be interesting to see what emerges.

Sadly I am of the opinion that if Boeing are "forced" to "go early" then they will play it safe.One one of the recent threads on the subject someone posted a 797 picture.It was like a shrunk 787-3 sort of.

Clearly it was an aircraft that they know they could build and would know what level of savings to expect.

The reason I raise this is that (to me) Airbus are not prone to risks.All their aircraft have been conservative.And before one says what about the 380 - it is really only a 747 on steroids.

As such if Boeing do not take a big risk - then nor will Airbus.

But working on the basis that I am 100% wrong (usually am) then I do see one common thought in these 3 designs.So much so that it appears to be a given.

That is (obviously) that they have removed the powerplants from the wing.This (being made of carbon) would allow them complete freedom to maximise its efficiency.

As for slightly forward swept as opposed to slightly swept - I am not in a position to know.I note Boeing has also played around with FSW.I guess with carbon the efficiency gains are not lost on weight which I believe was the historic problem.

2 have over (fuse) mounted engines. Efficient but hard for mantainance I guess.

As for the last one.It looks like a "Sonic Cruiser" European style.Aesthetic in the extreme.But looks low bypass which is no good today.And who (engine maker) has ever proposed it?

Rheinbote · Mon Sep 13, 2010 7:16 pm

Hard to believe the pumpkin orange design originated from Airbus. The rearmost door is misplaced, probably wouldn't open. The engine integration makes little sense beyond shielding the exhaust noise, the long S-duct is likely to create lotsa drag from frontal and wetted area. Engine segregation is lacking, an uncontained fire or a cracked tailpipe might take out one of the horizontal tails or burn into the fuselage. Judged by the exhaust nozzle the bypass ratio is 2 at best and the whole thing appears underpowered. Looks like space allocation for the main landing gear hasn't been given a thought yet.

Quoting keesje (Thread starter):
It seems they messed up the windows / doors to hide the scale.

And they put the cargo door on the wrong side then for what?

Starlionblue · Mon Sep 13, 2010 11:17 pm

Quoting parapente (Reply 1):

The reason I raise this is that (to me) Airbus are not prone to risks.All their aircraft have been conservative..

ALL aircraft designs nowadays are conservative. All designers keep optimizing previous ideas at this point.

Quoting parapente (Reply 1):
And before one says what about the 380 - it is really only a 747 on steroids.

Not really a 747 on steroids. They're both tubes with wings and they're both large. Within that, there are big differences. I will grant that the 380 is a conservative design. It is the least risky way to squeeze that many people into an 80x80 meter box.

Stitch · Mon Sep 13, 2010 11:26 pm

Maybe the Sonic Cruiser style engine mounting are designed to help reduce exhaust noise by ducting it over the rear aerofoil? The engines would be mounted low in the structure, I imagine, to allow for easy maintenance.

tdscanuck · Tue Sep 14, 2010 12:13 am

Quoting Starlionblue (Reply 3):
ALL aircraft designs nowadays are conservative. All designers keep optimizing previous ideas at this point.

I would argue that a major reason for the 787 delays is that it *wasn't* a conservative design. Other than general layout (hardly the most interesting of design features), a great deal of that airplane is clean sheet, rather than an optimization of a previous idea. Unless you consider it an optimized Sonic Cruiser, for which there is some argument, but then you have to admit the non-conservatism of the Sonic Cruiser.

Tom.

BMI727 · Tue Sep 14, 2010 12:30 am

Quoting parapente (Reply 1):
One one of the recent threads on the subject someone posted a 797 picture.It was like a shrunk 787-3 sort of.

That may be what it looks like, but under the skin it must be far more than a shrunken 787 if they want to make their investment worthwhile.

Quoting parapente (Reply 1):
That is (obviously) that they have removed the powerplants from the wing.This (being made of carbon) would allow them complete freedom to maximise its efficiency

The efficiency of the wing perhaps. But remember that without the engines to act as counterweights, the wings will need more structure internally. Secondly, that ducting weighs something and furthermore just about any other position other than the wings make more work for maintenance.

Quoting Rheinbote (Reply 2):
Looks like space allocation for the main landing gear hasn't been given a thought yet.

How about a taildragger?

Quoting Starlionblue (Reply 3):
ALL aircraft designs nowadays are conservative.

Airliner design is that way by nature. Just look at how long it was between the first composite aircraft until the 787.

Quoting Stitch (Reply 4):
Maybe the Sonic Cruiser style engine mounting are designed to help reduce exhaust noise by ducting it over the rear aerofoil?

Honestly, having heard how quiet the 787 is, I don't think that placing the engines inside or above the fuselage is necessary to make the plane quieter.

Starlionblue · Tue Sep 14, 2010 4:27 am

Quoting tdscanuck (Reply 5):
Quoting Starlionblue (Reply 3):
ALL aircraft designs nowadays are conservative. All designers keep optimizing previous ideas at this point.

I would argue that a major reason for the 787 delays is that it *wasn't* a conservative design. Other than general layout (hardly the most interesting of design features), a great deal of that airplane is clean sheet, rather than an optimization of a previous idea.

It guess it becomes a matter of definition. Do you define the design as the planform or all the stuff that is unseen under the skin.

However I will grant you the 787.

Rheinbote · Tue Sep 14, 2010 6:02 am

Quoting Stitch (Reply 4):
Maybe the Sonic Cruiser style engine mounting are designed to help reduce exhaust noise by ducting it over the rear aerofoil? The engines would be mounted low in the structure, I imagine, to allow for easy maintenance.

Yes, that's probably the line of thought behind the concept. But having the engine and the nozzle far apart in different places is a bad idea to start with. The good old hush-kits were a much less inefficient way of attenuating engine noise than these compromises of the overall configuration.

DocLightning · Tue Sep 14, 2010 7:02 am

Quoting keesje (Thread starter):

This pictures shows a more recent concept. It seems they messed up the windows / doors to hide the scale. I would not be suprized as this is a concept might be a twin aisle.

One major problem with rear-mounted engines is the Whitcomb area rule. The cross-section of such an aircraft increases toward the rear and then suddenly cuts off. The last image shows one solution to that problem, which is to widen the fuselage up front and narrow it over the wings, but then you are left with the issue of how to arrange the interior of the aircraft without wasting vast volumes.

One of the challenges that Boeing faced back in the Sonic Cruiser days was just this. The plane varied significantly from a classic Sears-Haack body. (http://www.dlr.de/as/Portaldata/5/Resources/dokumente/abteilungen/abt_ke/vorentwurf/hepperle-sonic-cruiser-paper.pdf [see figure 5]). The consequence of this is that at cruise, the flow over the wings would be very supersonic (M=1.5 at some points).

A conservative mid-hull monoplane with wing-mounted engines circumvents a lot of these problems. There is still a huge spike in cross-section at the wing. This is unavoidable. The engines, mounted forward of the wing, smooth out the sudden increase in cross-section. The flap track canoes do the same at the trailing edge and thus serve as anti-shock bodies (the canoes otherwise don't have to be nearly as big as they are).

Mounting the engines off the wing also increases fuselage length, and thus weight. This is the primary reason why rear-mounted engines have fallen out of favor, even in the RJ market. The only real advantage was that high-mounted engines were better operating out of semi-prepared airfields where FOD was an issue and where airstairs might not be available. Now that almost all airports with jet service have paved runways and airstairs, this is less of an issue.

I don't think that these fanciful designs will play out. I think that A30X will be an under-wing twin with a straight fuselage.

SchorschNG · Tue Sep 14, 2010 7:55 am

The "Blended Body Concept" is probably an industrial design study.
Honestly, the design has so many question marks that it would die the second a real engineer looks at it.
The whole fuselage concept is questionable, the idea of putting the engines there makes no sense at all.

And: airframers never publish the designs they are truly working on.
The high mounted engine concept are dead, too.
As are the twin vertical stabs.

parapente · Tue Sep 14, 2010 8:58 am

The thing I loved about the Sonic Cruiser was Boeing's "imagination".They were/are still trying to push the boundries.Whilst I do not believe it will happen I often hope that the designs of the World's greatest aircraft designer (Burt Rutan) could be found one day in a commercial aircraft.Last year I took my son to Seattle (skiing in Whistler too close to miss out on!).

I could not help but notice that "pride of place" in their museum had been given to the "Starship" a design that I feel perhaps inspired the Sonic Cruiser.

I would love the 797 to look something like that!But I don't suppose it will.

keesje · Tue Sep 14, 2010 11:51 am

Quoting DocLightning (Reply 9):
DocLightning

Thnx for your comments. Apart from all the disadvantages we can come up with, I think advantages might be (unparalleled low drag for the forward fuselage and (laminar) clean wings and noise levels not possible with under wing engines. The noise would be shielded downwards as well as to the sides by the vertical tail planes. For the passenger cabin noise isolation could be reduced. Maybe it would allowed to fly restricted airports/ runways / (night) times other aircraft are not allowed.

Quoting Rheinbote (Reply 2):
Judged by the exhaust nozzle the bypass ratio is 2 at best and the whole thing appears underpowered.

The L1011 tail RB211 had a BPR of 5 40 yrs ago.. On the BPR, I think the jet pipe is not so small, bigger then e.g v2500. https://www.airliners.net/photo/China...irlines/Airbus-A320-232/0770887/M/ I do not know why a BPR of say 10-14 would not be possible in this configuration.

Quoting parapente (Reply 11):
The thing I loved about the Sonic Cruiser was Boeing's "imagination".

I think it was a little m ore then imagination. Obviously Boeing believed in the concept.
http://www.boeing.com/news/releases/...01/photorelease/q3/pr_010917a.html

SchorschNG · Tue Sep 14, 2010 12:56 pm

Quoting keesje (Reply 12):
I think it was a little m ore then imagination. Obviously Boeing believed in the concept.

I doubt they did. Looking at what they came up with the B787, the Sonic Cruiser can probably considered a "smokescreen" project. I doubt they ever invested serious engineering effort in the concept. Apart from that, before you go to the customers you usually have done 5+ years of research and refinement.

Quoting keesje (Reply 12):
Apart from all the disadvantages we can come up with, I think advantages might be (unparalleled low drag for the forward fuselage and (laminar) clean wings and noise levels not possible with under wing engines. The noise would be shielded downwards as well as to the sides by the vertical tail planes. For the passenger cabin noise isolation could be reduced. Maybe it would allowed to fly restricted airports/ runways / (night) times other aircraft are not allowed.

Honestly, the biggest driver of noise of engines is the bypass. So reducing it is plain stupid.

----
Just to give people an idea of how "not really a design" this is: it still has an APU exhaust nozzle. Now Airbus heavily promotes the fuel cell as APU replacement, so why should aircraft 2030 actually have an APU exhaust nozzle?

keesje · Tue Sep 14, 2010 1:03 pm

Quoting SchorschNG (Reply 13):
Honestly, the biggest driver of noise of engines is the bypass. So reducing it is plain stupid.

I see room for a pretty large fan behind they wing, don't you?

BMI727 · Tue Sep 14, 2010 2:50 pm

Quoting parapente (Reply 11):
I could not help but notice that "pride of place" in their museum had been given to the "Starship" a design that I feel perhaps inspired the Sonic Cruiser.

The Sonic Cruiser's commercial prospects seem to have been inspired by the Starship too. But since you raise the topic of the Beechcraft Starship, I should perhaps point out the big lesson from that project: if it ain't broke, don't fix it. The only reason I see for a subsonic airliner to go with a radical engine placement like that would be if significant aerodynamic benefits could be derived from the cleaned up wing or moving the inlets and exhaust of the engine.

Oykie · Tue Sep 14, 2010 5:53 pm

Quoting keesje (Thread starter):
This could indicate Airbus still thinks the A320 will be replaced by 2 narrowbodies, a bigger and smaller one.

With the span from A318-A321, both the upper end, and lower end suffer a bit relatie to the original A320. With the E195 eating into the lower end of the market it seems like going with 2 narrowbodies is the way to go. Unless they abandon the A318/319 size completely..

Quoting parapente (Reply 1):
That is (obviously) that they have removed the powerplants from the wing.This (being made of carbon) would allow them complete freedom to maximise its efficiency.

So it seems. With the load challanges of rear mounted engines, and the potentially higher weight, I wonder if the pressure on noise pollution is so high that they will sacrifice this to get the plane more quiet. There is one plane with two large fans and a normal wing. To me this looks like the most mature design.

Quoting BMI727 (Reply 6):
That may be what it looks like, but under the skin it must be far more than a shrunken 787 if they want to make their investment worthwhile.

I have the feeling that the 737 replacement will be as close to the 787 as the 757 was to the 767. Same crew and many similar technologies.

Quoting SchorschNG (Reply 13):
I doubt they did. Looking at what they came up with the B787, the Sonic Cruiser can probably considered a "smokescreen" project. I doubt they ever invested serious engineering effort in the concept. Apart from that, before you go to the customers you usually have done 5+ years of research and refinement.

There was a lot of engineering effort going into the Sonic Cruiser. Just look at the 787, which uses much of that engineering effort.

BMI727 · Tue Sep 14, 2010 7:40 pm

Quoting OyKIE (Reply 16):
I have the feeling that the 737 replacement will be as close to the 787 as the 757 was to the 767. Same crew and many similar technologies.

Certainly all the advances from the 787 will make it into the Y1. What I'm saying is that Boeing will need to go another step and find more advances for the Y1. If the Y1 and 787 have the same relationship as the 757 and 767 Boeing should already be getting ready to fly it. They could have launched it five years ago or so (and they had customers) but didn't because it wasn't worth their while.

If all the Y1 would be now is a smaller 787, they might as well just stick with a revamped and possibly re-engined 737 and wait until they have something better.

SchorschNG · Tue Sep 14, 2010 9:38 pm

Quoting OyKIE (Reply 16):

There was a lot of engineering effort going into the Sonic Cruiser. Just look at the 787, which uses much of that engineering effort.

They didn't have an engine, and most stuff was basically proving concepts of the B787, which apparently was in the pipeline for some time. Boeing started serious work on the Sonic Cruiser in 1999, didn't do wind tunnel before 2001 and never showed real high-lift design or engine intake.
You cannot walk to airlines and sell a concept, you need several 10000 engineering hours to have something.
When you try a more advanced "high risk" concept like the Sonic Cruiser, you'll need much more.
I doubt Boeing ever considered the Sonic Cruiser a viable product. Remember: Boeing originally only wanted to spent ~4 Billion USD on the B787, the rest was supposed to come from "risk share partners".

Oykie · Thu Sep 16, 2010 7:37 pm

Quoting SchorschNG (Reply 18):
They didn't have an engine, and most stuff was basically proving concepts of the B787, which apparently was in the pipeline for some time.

According to my info the engines would be based on the same core as the higher thrust 777 engines. But not sure how far that got. Anyway. To continue the thread. I really like to see these radical design. It gives us a glimpse of how we believe the future might be today. I even like to read about ideas for year 2000 about 30-50 years ago.

XT6Wagon · Fri Sep 17, 2010 4:30 pm

Quoting SchorschNG (Reply 13):
I doubt they did. Looking at what they came up with the B787, the Sonic Cruiser can probably considered a "smokescreen" project. I doubt they ever invested serious engineering effort in the concept. Apart from that, before you go to the customers you usually have done 5+ years of research and refinement.

Wrong, they were very serious about the sonic cruiser. It would have been cheaper to operate than the 787 in an era of cheap, stable fuel prices. Trip fuel burn comparable to the 767, but massive savings in crew and MX costs. (reduction of hours in the air). When the gas prices spiked, switching to a more conventional design was called for and done.

In fact I'd almost put money on Boeing still having a few people working on the sonic cruiser as techologies to deal with high transonic flight might still be very important to have going forward.

SchorschNG · Sat Sep 18, 2010 3:05 pm

Quoting XT6Wagon (Reply 20):
In fact I'd almost put money on Boeing still having a few people working on the sonic cruiser as techologies to deal with high transonic flight might still be very important to have going forward.

Boeing basically created the Sonic Cruiser idea in 1999 with an initial engineering team of 12 (in words: twelve) engineers.
The Sonic Cruiser was a maximum risk design, with many technical unknown unknowns.
Today only airliners are built which operate in fully understood regimes.
Even slight deviations like producing part of the structure with CFRP (which is done in industry since 30 years, so not totally new) already endangers a program.

The Sonic Cruiser would have needed at least 10 years development, refinement and definition.

Fun fact: there is only a single real "document" available giving specifications of the Sonic Cruiser. And it wasn't written by Boeing.
See: http://www.mh-aerotools.de/company/paper_7/astec_2002.htm
While performance predictions for "conventional" aircraft are a fairly simple thing, the Sonic Cruiser would have been high risk even here.

tdscanuck · Sat Sep 18, 2010 4:03 pm

Quoting SchorschNG (Reply 21):
Fun fact: there is only a single real "document" available giving specifications of the Sonic Cruiser. And it wasn't written by Boeing.

Funny thing about facts...you need to do your research. I'm currently starting at a list of 12+ documents, every single one written by Boeing, giving specifications for the Sonic Cruiser.

Tom.

Stitch · Sat Sep 18, 2010 5:03 pm

Quoting SchorschNG (Reply 13):
I doubt (Boeing) did (consider the Sonic Cruiser a real program). Looking at what they came up with the B787, the Sonic Cruiser can probably considered a "smokescreen" project. I doubt they ever invested serious engineering effort in the concept.

I worked on it and all I can say was at the time, those of us on the program operated under the assumption it would enter service if customers placed orders.

Quoting SchorschNG (Reply 13):
Before you go to the customers you usually have done 5+ years of research and refinement.

Suppose it depends on the customer. Arpey might have been blowing smoke when he said he would like to order the first three years of production for AA, but then again, maybe he wasn't...

XT6Wagon · Sat Sep 18, 2010 5:14 pm

Quoting Stitch (Reply 23):
Arpey might have been blowing smoke when he said he would like to order the first three years of production for AA, but then again, maybe he wasn't...

As more and more routes push durations that require 1.5 or 2 crews per flight, I am betting you will see more and more push for even faster speeds. Certainly we have seen that Airlines not willing to accept planes with a rated cruise lower than .85. Shaving 30min or more on a flight can have startling cost savings if you can duck extra crew requirements by doing so.

SchorschNG · Sun Sep 19, 2010 8:59 am

Quoting XT6Wagon (Reply 24):
As more and more routes push durations that require 1.5 or 2 crews per flight, I am betting you will see more and more push for even faster speeds. Certainly we have seen that Airlines not willing to accept planes with a rated cruise lower than .85. Shaving 30min or more on a flight can have startling cost savings if you can duck extra crew requirements by doing so.

Maybe we should rather look at single pilot operation during cruise flight (not the entire flight).

Quoting tdscanuck (Reply 22):
Funny thing about facts...you need to do your research. I'm currently starting at a list of 12+ documents, every single one written by Boeing, giving specifications for the Sonic Cruiser.

They are probably not public domain and I guess you are not willing to share them in any way?

tdscanuck · Sun Sep 19, 2010 2:21 pm

Quoting SchorschNG (Reply 25):
Maybe we should rather look at single pilot operation during cruise flight (not the entire flight).

I think that's probably a very sensible way to go...it would unload the crewrest/crew seating considerably on very long haul if you could have both crews takeoff, then one go to sleep at top of climb, swap in the middle, then have both land.

Quoting SchorschNG (Reply 25):
They are probably not public domain and I guess you are not willing to share them in any way?

They are indeed not public domain and I'm not in any position to share them here, unfortunately.

Tom.

Rheinbote · Sat Sep 25, 2010 7:53 pm

Quoting XT6Wagon (Reply 20):
Trip fuel burn comparable to the 767, but massive savings in crew and MX costs. (reduction of hours in the air)

So you think the SC would have had a lower utilization in hours/day than a 767? And what about MX based on the number of cycles? Wouldn't the higher speed have had an impact on MX cost (engines, loads, materials)?

XT6Wagon · Sun Sep 26, 2010 4:14 pm

Quoting Rheinbote (Reply 27):
So you think the SC would have had a lower utilization in hours/day than a 767? And what about MX based on the number of cycles? Wouldn't the higher speed have had an impact on MX cost (engines, loads, materials)?

Yes, Many of these long routes would still be restricted by slots and/or desirable times to the same number of flights per day as current. Some would see more cycles in a day on shorter routes where it lets an operator put in one more leg per day. The additional revenue should pay for the additional wear, as with any other airliner.

We won't know exactly what it would cost, but I'm guessing the extra cost would be centered in the engines. Paint might be an additional area of extra expense, but I don't know how much. Overall I suspect that they would have used a new generation of engines and the composite fuselage to keep the overall costs lower, thus hiding the extra costs more speed brings.

keesje · Tue Dec 28, 2010 5:38 pm

Some new visuals on the BWB concept. Major advantages od this A320 replacement seem to be it is suitable to fit high BPR turbo fans, it's able to make a difference in exhaust noise and different lenghts are possible.

jwenting · Tue Dec 28, 2010 6:03 pm

sounds like a blend between the ducted fan powered MD90 derivative and the original Sonic Cruiser.
Perfect thinking: "let's take parts of 2 failed designs that made them fail, put those together, and we have a sure winner with the subsidy machines in Brussels to milk for years and years".

777236ER · Tue Dec 28, 2010 6:09 pm

Quoting jwenting (Reply 30):
et's take parts of 2 failed designs that made them fail, put those together, and we have a sure winner with the subsidy machines in Brussels to milk for years and years

I'm not sure you're using 'to milk' in the context you mean it. Of course, you could be correct - the European governments have been collecting significant royalty payments from the A320 for years.

Stitch · Tue Dec 28, 2010 10:28 pm

I can't see how an Open Rotor issue would be able to fit in there, so I wonder if Airbus feels OR will never be commercially viable...

Faro · Wed Dec 29, 2010 12:25 am

Quoting keesje (Thread starter):
laminar flow wings

IIRC, this is very hard to achieve and maintain. I suppose you mean laminar flow over, say, the first 10-20% of wing chord only? Unless of course there's some new breakthrough in this field...

Faro

Aesma · Wed Dec 29, 2010 2:27 am

Quoting stitch (Reply 32):
I can't see how an Open Rotor issue would be able to fit in there, so I wonder if Airbus feels OR will never be commercially viable...

I guess they would put them above the tail, removing the "ducts". It would be a change of position for the engines, but the rest of the plane would stay the same.

What is the advantage of those ducts by the way ? I understand the noise gain, but I thought ducts like that where inefficient. And isn't the thrust coming out upwards ? Does the plane fly pitched up ?

tdscanuck · Wed Dec 29, 2010 3:55 am

Quoting keesje (Reply 29):
Some new visuals on the BWB concept.

Am I missing something? Nothing pictured there is a BWB.

Quoting faro (Reply 33):
IIRC, this is very hard to achieve and maintain. I suppose you mean laminar flow over, say, the first 10-20% of wing chord only? Unless of course there's some new breakthrough in this field...

Laminar flow over the whole wing is very difficult to maintain in a commercially viable way, but there are lots of people working on it. It's easy to do if you use active technologies like boundary layer suction...the trick is making those technologies economical and certifiable, or finding something entirely new. There are some very interesting surface treatments out there with promise.

Quoting Aesma (Reply 34):
What is the advantage of those ducts by the way ?

The only advantage I can see is you're pulling air off the high-pressure side of the wing, which makes the inlet/wing interaction easier to deal with.

Quoting Aesma (Reply 34):
I understand the noise gain, but I thought ducts like that where inefficient. And isn't the thrust coming out upwards ? Does the plane fly pitched up ?

I think the engines themselves are still nearly flat, it's just the inlets that are sloped.

Tom.

BMI727 · Wed Dec 29, 2010 4:30 am

Quoting keesje (Reply 29):

Some new visuals on the BWB concept

That doesn't look like BWB to me. Maybe you got the wrong pictures.

Quoting stitch (Reply 32):
I can't see how an Open Rotor issue would be able to fit in there, so I wonder if Airbus feels OR will never be commercially viable...

And I'm not sure why you would waste weight with such a long intake or exhaust duct either.

Quoting faro (Reply 33):
Unless of course there's some new breakthrough in this field...

The HondaJet is using natural laminar flow wings. There is a technical paper on their website which I haven't gotten around to reading yet. Of course applying that technology to a wing with a span nearly three times that of the HondaJet is probably not especially easy.

Quoting Aesma (Reply 34):
I understand the noise gain, but I thought ducts like that where inefficient.

Well, it's extra weight if nothing else. Beyond that it won't be particularly easy to access for maintenance. Beyond that, I don't see why the twin tails are necessary, other than to drive the point home that this isn't you daddy's Airbus. Seems like more unnecessary weight and complication.

Aesma · Wed Dec 29, 2010 2:11 pm

Were inefficient and not "where", I shouldn't post when too tired.

Quoting tdscanuck (Reply 35):
The only advantage I can see is you're pulling air off the high-pressure side of the wing, which makes the inlet/wing interaction easier to deal with.

Makes sense.

Quoting tdscanuck (Reply 35):
I think the engines themselves are still nearly flat, it's just the inlets that are sloped.

But the outlets also do seem to point up.

Quoting BMI727 (Reply 36):
Beyond that it won't be particularly easy to access for maintenance.

I often read that here, but isn't there less and less maintenance on new engines ? And depending on where they are exactly inside the duct, it shouldn't be that bad with big access panels.

tdscanuck · Wed Dec 29, 2010 5:09 pm

Quoting Aesma (Reply 37):

But the outlets also do seem to point up.

They look like scarfed inlets (cut back at an angle) to me, rather than actually pointed up. That looks like noise mitigation, rather than a different thrust line.

Tom.

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