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Future Of Blended Wing Commerical Aircraft  
User currently offlineMason From United States of America, joined Jun 1999, 748 posts, RR: 1
Posted (9 years 4 months 2 weeks 4 days 22 hours ago) and read 4589 times:

It's been a few years since serious mention of this was made. Both Boeing and Airbus had undertaken research activities to look into Blended Wing Body (BWB) aircraft, similar to the Northrop YB-49. The idea is to use the entire surface, or a significantly larger percentage of the surface area to produce lift, therefore reducing operating costs. These designs also offer increased strength over the conventional design, where the fusalage is essentially dead weight. I have included some links with more information and pictures. What do you think of a blended wing aircraft? Unlikely Boeing will persue this for some time, with the 787 project. Could this be the opportunity for Airbus to break out? Too risky? Personally, I think it's a great idea, and within 30 years we will be flying inside the wing!

http://www.twitt.org/bldwing.htm
http://www.flug-revue.rotor.com/FRheft/FRH0101/FR0101e.htm

25 replies: All unread, showing first 25:
 
User currently offlineGlom From United Kingdom, joined Apr 2005, 2818 posts, RR: 10
Reply 1, posted (9 years 4 months 2 weeks 4 days 21 hours ago) and read 4529 times:

The problems associated with BWB is the lack of windows, but I'm sure someone will think of some design that will make it passenger friendly.

I don't think the 787 will slow down Boeing to allow Airbus to take the lead on this. The A350 will delay Airbus by even longer.


User currently offlineHiFi From Brazil, joined Apr 2005, 192 posts, RR: 0
Reply 2, posted (9 years 4 months 2 weeks 4 days 21 hours ago) and read 4487 times:

Hi.
Not a very catchy idea in my opinion. A lot of safety issues come to mind.. For example, engine position. We have seen lots of progress during the last decades to prevent rotor bursts from seriously damaging an aircraft. A Concorde-like layout would be very difficult to certify nowadays...
Of course it's very hard to assess rotor burst risks without knowing exactly where the fuel tanks are, which regions are pressurized, how essential systems are arranged, etc.. but I still think it might be a barrier to such a design.

Another point is: are BWB designs really aerodynamically superior? Maybe some aerodynamics people should help me on this one. Sure, lift is better. But you significantly increase wet area... what about drag? Have existing BWB aircraft proven themselves more efficient?

Also, start getting used to aisle seats, as windows would probably be very hard to get in BWB aircraft.  Wink



no commercial potential
User currently offlineOldAeroGuy From United States of America, joined Dec 2004, 3527 posts, RR: 67
Reply 3, posted (9 years 4 months 2 weeks 4 days 21 hours ago) and read 4469 times:

There are some major issues that I've never seen adequately addressed:

- Emergency egress with a collapsed main gear.
- Maneuvering loads on passengers located at the most outboard seating locations.
- Cargo capacity and loading issues.
- Pressurization issues

Contrary to popular belief, the advantages of a blended wing/body is not in aerodynamics. The biggest gain is the distribution of payload along the lifting surface and an attendant reduction in structural weight.



Airplane design is easy, the difficulty is getting them to fly - Barnes Wallis
User currently offlineSBN580 From United States of America, joined Mar 2005, 401 posts, RR: 3
Reply 4, posted (9 years 4 months 2 weeks 4 days 21 hours ago) and read 4457 times:

http://www.twitt.org/BWBBowers.html

Here's a paper written by one of my favorite engineers I worked with at NASA Dryden, Al Bowers. He was in charge of the BWB work for Dryden around 2000. I can find no references to the program still being active, I am sad to say. It's a great idea.



North Central: Good People Made Their Airline Great! FLY MD-90 POWER! Keep 'em Flying DELTA Family!
User currently offlineWhiteHatter From , joined Dec 1969, posts, RR:
Reply 5, posted (9 years 4 months 2 weeks 4 days 21 hours ago) and read 4438 times:

If you do some sniffing around certain websites concerning so-called 'black' projects, there is usually some chatter about freighters and tactical airlifters being built to this design. A tank doesn't need a window.

There was some detailed speculation concerning a USAF freighter/lifter design which would eventually be introduced which has the blended wing/body design, but is currently classified. The basics in tunnel testing and B2 operation data are already there to start the project off. Less vertical surfaces also help make the design more stealthy.


User currently offlineMason From United States of America, joined Jun 1999, 748 posts, RR: 1
Reply 6, posted (9 years 4 months 2 weeks 4 days 20 hours ago) and read 4392 times:

Interesting observations. I am always impressed with the knowledge in this forum. While we're discussing aerodymanics, what about canards (small wings on the forward fusalage)? I know these have also been studied, but never implemented. My grandpa is an ex-Boeing windtunnel manager, so I've seen all sorts of concepts. Early 757/767 as a tri-jet, T-tail, even a 767 with an upper deck running the rear 2/3 of the fusalage! To me, the BWB seems like the most likely prototype, pressurization and window issues resolved.

User currently offlineRIX From United States of America, joined Aug 2000, 1787 posts, RR: 1
Reply 7, posted (9 years 4 months 2 weeks 4 days 13 hours ago) and read 4244 times:

Pressurization... Windows... Emergency evacuation... "Maneuvering loads on passengers located at the most outboard seating locations"... each of these is a serious issue, but none is an issue for a freighter. Don't know about passenger aircraft, but BWB freighter looks quite probable.

User currently offline2H4 From United States of America, joined Oct 2004, 8955 posts, RR: 60
Reply 8, posted (9 years 4 months 2 weeks 4 days 12 hours ago) and read 4177 times:
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DATABASE EDITOR

Boy, I've got to think ground maneuvering would be another difficult issue to solve.


2H4





Intentionally Left Blank
User currently offlineLehpron From United States of America, joined Jul 2001, 7028 posts, RR: 21
Reply 9, posted (9 years 4 months 2 weeks 4 days 7 hours ago) and read 4066 times:

Quoting HiFi (Reply 2):
are BWB designs really aerodynamically superior? Maybe some aerodynamics people should help me on this one. Sure, lift is better. But you significantly increase wet area... what about drag? Have existing BWB aircraft proven themselves more efficient?

Yes, some or a properly designed BWB, may have aerodynamically superior performance. Think of a regular plane with no fuselage, you're literally cutting your parasite drag in half, or more. That alone has the greatest impact on range, but the increased profile may reduce the cruise speed to Mach 0.78 or so. Again, if designed right.

Pressurizing a flying hockey puck is a different story. Air naturally wants to be a sphere, hence a bubble. Unless you integrate a flying ball 60-feet wide with 400 people on multiple decks...I donno.

Either way, there currently isn't a whole lot of money going into it, so the knowledge gained is at a minimum rate. After a while, all of the knowledge gained sound the same and people loose interest in investment. Considering how most airplanes are built, this is totally out there resulting in high manufacturing costs which is part of the development.

The point of the BWB I think was to be able to pack pax while maintaining a serviceable size, but the A380 proves that this can still be done with traditional shapes, so why put the investment is something new and different?

So far the only blended wing body that has proven itself for its uses is the B-2 Spirit.

That said, it is not a flying hockey puck, it barely retains a traditional tube fuselage, I figure a BWB doesn't have to look like what people so far seen -- its what i mean by design right.

I think it can still be done, per se. Just gotta expand your mind a bit.



The meaning of life is curiosity; we were put on this planet to explore opportunities.
User currently offlineAeroWeanie From United States of America, joined Dec 2004, 1609 posts, RR: 52
Reply 10, posted (9 years 4 months 2 weeks 4 days 6 hours ago) and read 4016 times:
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Bob Liebeck at McDonnell Douglas and now Boeing has been heading up a project to study the design of a BWB. He's been at it for about 10 years now and gets a bit of funding from NASA. Problem is, he is down at Long Beach and I don't think Boeing Seattle takes his project too seriously. His group has published a number of SAE and AIAA papers on the topic and he gave an AIAA dinner meeting presentation up here in Seattle 3 years ago. During the dinner meeting, there was a jack hammer going away on the street outside and he kept joking "someone go out and tell Alan to knock it off!" I'll leave it to you to guess who he was referring to...

User currently offlineSebolino From France, joined May 2001, 3681 posts, RR: 4
Reply 11, posted (9 years 4 months 2 weeks 4 days 5 hours ago) and read 3980 times:

The website you provided says this about the A380:

The fin will tower 75 feet above the tarmac, but no ordinary tarmac will be able to support its massive one million, eighty four thousand pound takeoff weight. Such a huge shape will also cause problems with wake vortex, passenger circulation and comfort, plus the daunting attendant psychology in flying in something that big. At a greatly higher price than the newest 747, it will only hold 75 more passengers without any significant increase in speed or range.

They are definitely not very serious !
The idea of a flying wing is however very interesting.


User currently offlineMason From United States of America, joined Jun 1999, 748 posts, RR: 1
Reply 12, posted (9 years 4 months 2 weeks 4 days ago) and read 3860 times:

Well given all the airports having to make accomidations for the A380s size and weight, I don't think they were too far off.

User currently offlineOldAeroGuy From United States of America, joined Dec 2004, 3527 posts, RR: 67
Reply 13, posted (9 years 4 months 2 weeks 4 days ago) and read 3861 times:

Quoting Lehpron (Reply 9):
Yes, some or a properly designed BWB, may have aerodynamically superior performance. Think of a regular plane with no fuselage, you're literally cutting your parasite drag in half, or more

That sounds great, but you can't just eliminate the fuselage and keep the wing. Wing size must be increased to provide the volume to hold the passengers. You end up adding additional wetted area and/or additional profile drag due to increased wing thickness.

A practical BWB probably can't work below a given passenger size due to volume constraints. Around 250 springs to mind, but I haven't done a comprehensive data review. Not a candidate for replacement of the A320/737.

Quoting Mason (Reply 6):
While we're discussing aerodynamics, what about canards (small wings on the forward fuselage)?

The main value of canards is you can have a stall free configuration.

Other than that, stable canards will always be less efficient than a conventional configuration.



Airplane design is easy, the difficulty is getting them to fly - Barnes Wallis
User currently offlineRayChuang From United States of America, joined Jun 2000, 8018 posts, RR: 5
Reply 14, posted (9 years 4 months 2 weeks 3 days 23 hours ago) and read 3787 times:

I think the BWB airplane will find its primary niche as a cargo carrier.

Imagine being able to carry more cargo than the A380-800F (and carry outsized cargo, too!) with lower fuel burn than the A388F and/or longer range than the A388F!  bigthumbsup  Such a plane would be of great interest to FedEx, UPS, CargoLux, and the air cargo divisions of LH, SQ, CX and NW.


User currently offlineLehpron From United States of America, joined Jul 2001, 7028 posts, RR: 21
Reply 15, posted (9 years 4 months 1 week 4 days 9 hours ago) and read 3596 times:

Quoting Mason (Reply 12):
Well given all the airports having to make accomidations for the A380s size and weight, I don't think they were too far off.

The intial reason for the BWB research was a platform that could take more capacity as a reference aircraft at the same scale, up to twice capacity in fact.

Quoting OldAeroGuy (Reply 13):
Wing size must be increased to provide the volume to hold the passengers.

Duh, I was talking about said 'aerodynamic efficiencies'.  irked  With traditional airplanes, there is a drag loss due to wing & fuselage interactions, a blended fillet can reduce these effects, i.e. look at Lockheed SR-71 and its sloped fuselage chimes. Also consider the effect of lift-to-drag on a fuselage maxes as 0.05 or less.

Quoting OldAeroGuy (Reply 13):
A practical BWB probably can't work below a given passenger size due to volume constraints. Around 250 springs to mind, but I haven't done a comprehensive data review. Not a candidate for replacement of the A320/737.

Like I've said, if done right, anything can work. Perhaps I should ask what shape is your baseline for all future possible combinations of the design to call it 'practical'? With all due respect, a flying wing and a blended body wing are not the same thing, though they can have the same function, big deal. In addition, Boeing and NASA's BWB concepts they were studying were different as well, just NASA'a version was well publicized as the pax flying wing. Boeing's concept was much different, it had a lower parasite drag component. I remember seeing it before Boeing took it off their website a few years back. They were basically high winged aircraft where the wing's chord travelled 80% of the plane's length.

I tried to recreate from what I remember, take a gander:

They even insinuated the shape they settled on could support carriers with needs from 150 pax out to 1,000 pax all while keeping the overall size and MTOW doen compared to traditional airliners. The issue of practicality is just a reminder of what we are used to and good at compared with what is unproven simply because no one has been willing to try up until now. Less investment doesn't mean something doesn't work, just there was no real intent to be serious in the first place, except for PR. It's why we don't have widespread electric cars, we like our oil.



The meaning of life is curiosity; we were put on this planet to explore opportunities.
User currently offline2H4 From United States of America, joined Oct 2004, 8955 posts, RR: 60
Reply 16, posted (9 years 4 months 1 week 4 days 9 hours ago) and read 3579 times:
AIRLINERS.NET CREW
DATABASE EDITOR

Quoting OldAeroGuy (Reply 13):
The main value of canards is you can have a stall free configuration.

Other than that, stable canards will always be less efficient than a conventional configuration.

I was under the impression three lifting surfaces was generally more efficient than the conventional wing and tail configuration. Isn't the Piaggio Avanti's much-touted speed and efficiency based on it's canard configuration?


2H4





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User currently offlineIwok From Sweden, joined Jan 2005, 1108 posts, RR: 0
Reply 17, posted (9 years 4 months 1 week 4 days 9 hours ago) and read 3544 times:

-----edited-----
-----see next post -----

[Edited 2005-05-25 07:20:50]

User currently offlineIwok From Sweden, joined Jan 2005, 1108 posts, RR: 0
Reply 18, posted (9 years 4 months 1 week 4 days 8 hours ago) and read 3536 times:

I have also been pretty interested in the BWB. But there are many problems with the idea for pax. My main issue is that it will be like sitting in a movie theater for 12-hours.

Interesting comparison is available at:
http://www.aerosite.net/bwb.htm



The intersting thing about this a/c is that it would be lighter than the 380 by about 15-20% and yet carry 67% more passengers. However, it is probably better off as a freighter since windows are not needed.

This article has an interesting paper by Boeing on the benefits of the BWB freighter. It also talks about "formation flying" to reduce fuel consumption. I think the analogy is similar to a flight of geese.

BWB frieghter

-iwok


User currently offlineEilennaei From , joined Dec 1969, posts, RR:
Reply 19, posted (9 years 4 months 1 week 4 days 8 hours ago) and read 3522 times:

Quoting Lehpron (Reply 9):
Pressurizing a flying hockey puck is a different story. Air naturally wants to be a sphere, hence a bubble

Splitting hairs, but by nature air, being a gas, does not prefer any particular shape, it just fills all the available space. Most existing designs are more or less irregular tubes rather than spheres, against the dictionary definition of a "three-dimensional closed surface such that every point on the surface is equidistant from the center"

-Eilennaei


User currently offline3201 From , joined Dec 1969, posts, RR:
Reply 20, posted (9 years 4 months 1 week 4 days 8 hours ago) and read 3503 times:

In a previous life, I was very close to a lot of serious BWB research, and all I can say is Lehpron and the rest of you young guys, you should listen to your elders, because in my opinion the two most accurate comments on this thread are these:

Quoting OldAeroGuy (Reply 3):

Contrary to popular belief, the advantages of a blended wing/body is not in aerodynamics. The biggest gain is the distribution of payload along the lifting surface and an attendant reduction in structural weight.

(If you don't know what he means, look at wing load distributions with both lift and weight, the weight of the fuselage, engines, payload, etc. -- especially of a conventional tube-and-wings at max zfw and no fuel; then compare to a BWB at same payload and fuel load)

Quoting AeroWeanie (Reply 10):
Problem is, he is down at Long Beach and I don't think Boeing Seattle takes his project too seriously.

Regarding the freighter refocus, there was at least one, probably more, paper on that at the AIAA 100 years of flight conference in Dayton, shouldn't be too tough to track down.

Personally, I have a deep hatred of the A380, not because I think it's too big or because I'm an Airbus-hater, but because in that size aircraft it's finally feasible to do a BWB, but there's only demand for (at most) one aircraft, so the stupid tube-and-wing thing kept the BWB passenger transport from becoming an immediate reality -- and for that, I won't forgive Airbus.


User currently offlineA350 From Germany, joined Nov 2004, 1100 posts, RR: 22
Reply 21, posted (9 years 4 months 1 week 3 days 18 hours ago) and read 3367 times:

@Mason: thanks for the great links!

Although I can't imagine BWBs to come anytime soon, I'm quite optimist they'll play a big role in maybe 20 or 30 years as A380 replacements. My reasons are:
  • air travel and global economy will ever grow, but energy resources won't grow, so fuel efficiency (no regard which fuel is used) will become the number one priority.
  • a BWB will always be far more fuel efficient than a tube-and-wing a/c built with the same materials, engines, avionics etc.
  • all technical issues of a BWB can be solved, there is no show-stopper
  • The young generation accepts virtual reality much more than the older ones, they will accept PTVs as "virtual windows" .
  • already today people accept being far away from the next window for long hours in ships like cruising ships or ferries.


Just my  twocents 

A350



Photography - the art of observing, not the art of arranging
User currently offlineMason From United States of America, joined Jun 1999, 748 posts, RR: 1
Reply 22, posted (9 years 4 months 1 week 3 days 17 hours ago) and read 3320 times:

Hey, A350, thanks for your optimistic attitude. I totally agree on every point. The problems can and will be solved in order to cope with energy requirements and the global energy situation, which is in constant debate.

User currently offlineMD-90 From United States of America, joined Jan 2000, 8508 posts, RR: 12
Reply 23, posted (9 years 4 months 1 week 3 days 17 hours ago) and read 3260 times:

Quoting 2H4 (Reply 16):
Isn't the Piaggio Avanti's much-touted speed and efficiency based on it's canard configuration?

The big reason is because the foreplane and tailplane both provide lift. The foreplane is actually not a canard, since it's not used to change the pitch of the aircraft. The horizontal tail does not provide downforce (which, ultimately, has to be overcome by the lift of the wing), which means that the wing can be smaller (and the Piaggio has a very small wing: it's only barely larger than a 172 in surface area).

http://www.twitt.org/BWBBowers.html

One of the more interesting facets of this design was the position of the engine inlets. Since they are right down on the wing surface, they are ingesting the boundary layer so any airflow sucked into the engines can be ignored as drag. This gives a huge increase in the L/D due to the decrease in drag.

I thought that was pretty interesting.

[Edited 2005-05-25 23:18:08]

User currently offlineKeesje From , joined Dec 1969, posts, RR:
Reply 24, posted (9 years 4 months 1 week 3 days 16 hours ago) and read 3238 times:

A brand new aircraft development like the B787 appears to require an investment of $10 Billion. One has to sell many hundreds to break even.

A BWB design would likely be an enormous investment. If it´s use is limited to freight, a large military program to start with might be necessary.

I agree with Oldaeroguy on design issues. Pressuring such a flat shaped cabin will translate into enormous tensions & structural weight issues compared to a simple tube..

Also stretching / shrinking to create a family seems more complicated.


User currently offlineAreopagus From United States of America, joined Sep 2001, 1369 posts, RR: 1
Reply 25, posted (9 years 4 months 1 week 3 days 14 hours ago) and read 3165 times:

Quoting MD-90 (Reply 23):
The foreplane is actually not a canard, since it's not used to change the pitch of the aircraft.

That's funny. A description I read of the Curtiss XP-55 Ascender (or "Ass-ender") says that it was not technically a canard design, as there was no fixed surface forward: it was all-movable for control.

Quoting Keesje (Reply 24):
Pressuring such a flat shaped cabin will translate into enormous tensions & structural weight issues compared to a simple tube.

If it's built like an A380 fuselage tipped on its side, it shouldn't be so bad. That is, a series of circular sections with a web structure (instead of a floor) at the joins, which acts as a partition between bays of passengers.


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