There's a great deal of interest in blended wing-bodies (BWB) all of a sudden. Yesterday the Silent Aircraft Initiative people unveiled a chunk of their work, which we wrote about. There is plenty of other work going on, such as this at Cranfield University. And Boeing will fly the X-48B model early next year.
I suppose there are two broad motivators behind all this: the potential for carrying very large passenger loads economically, and other environmental issues, especially noise. There are compelling reasons why this really could become reality.
But here's a paradox. The main objection that is raised to the idea just about wherever it is discussed, here for example, is the increased likelihood of passenger airsickness mainly owing to a) their distance from the longitudinal axis b) the absence of windows for many of them. The paradox is that, as far as I can see, in all the public domain literature on the subject (and there is a lot) that issue is scarcely or never mentioned. I don't know if that's because the researchers have already concluded that it's a non-issue, or perhaps they can't do any useful research without a full-size aircraft.
Anyway, if it is a problem then it does seem extremely difficult to fix it - a potential showstopper. But I wonder about the logic of the argument. Hardly anyone ever seems to be airsick these days, which I suspect (just my guess) is mainly down to improved ride, particularly on fly-by-wire types. That's even though plenty of passengers are yards away from a window, and in any case there is often no visible horizon.
On a BWB the big differences are that a) some people have no window at all and b) perhaps more important, many will be a long way from the centreline of the aircraft and so subject to much greater vertical movement than usual during turns.
Now if this really does cause widespread airsickness than that is a big problem and it's not obvious what the solution is. But will it? It seems to me that it's only as the aircraft is actually rolling into the turn that the situation is much different from now - once you're established in the turn then it doesn't matter how wide the aircraft is or where you're sitting. And the general ride will be incredibly smooth.
(I've got a personal obsession with windows - but it's nothing to do with airsickness and I'll save it for another post.) If you've got thoughts on the BWB issue leave a comment.
Your obsession with windows is not personal, it's shared by the rest of humanity. We all need an open vista to be happy. It's quite visceral to want to look at the real ground and clouds and not be subjected to in-flight "entertainment". For subsonic flight, a conventional configuration has the same optimality and longevity as the wheel, the bike, and the internal combustion engine. Give me my stick and tube..
Regards.
Dr Dimitri Simos
According to some Russian researchers in 1998 the vertical motion far from the longitudinal axis will spill your coffee. Their solution was a "semi-blended" wing body.
David Nixon
Video screens. You place video screens with a simulated exterior image. I always fly aisle seat and I have no problems with this lack of window, air sickness problem. Wimps.
Rob Coppinger
The big show-stopper seems to me to be the escape requirements - where will the emergency exits be ? Will the 200-odd passengers be able to get out within the 90 seconds ?
Electronics will probably take care of yaw spilling coffee on entry into turns, while there's no reason not to give passengers an "outside view" via the seat-back screen. But getting on & off the BWB - emergency or no - is a puzzlement ...
And don't forget that Aerospatiale (as was) was working on a similar "post-A380" many a year ago ...
Carry on blogging !!!
John Price
Quite a bit of work been done and being done on the evacuation issue. Take a look here: http://fseg.gre.ac.uk/fire/fseg_verres_WP2_modelling.pdf
Kieran Daly
Some researchers (Martinez Val, Spain) state that emergency evacuation could be achive, as regulated in current FAR/JAR regulations, for a mid-size flywing wing. Nevertheless, as indicated in a previous post, the emergency evacuation is the main show-stopper for both flying wings and blended wing bodys of 450 pax or higher. Maybe, a new kind of aircraft requires a new kind of regulation. Category F of ICAO for Aircraft didn't exist up to the A380 project.
And regarding to the bumps due to the offset from the longitudinal axis, you must bear in mind several issues like how are the modes of stability of the aircraft, the fly by wire system and another important matter: because of its higher wing surface, the wing loading of this kind of aircraft is lower than that of the conventional aircraft, as a result, they could fly higher, 50000 ft cruise altitude is fairly feasible with the appropriate engine. At that flight level the atmoshphere is much calmer, thus, lowering the neccesity of maneouver.
I'm looking forward to reading your comments!
JPM
It's pretty much a non-issue - studies show that the ride quality of the BWB is within a few percent of that of existing conventional airliners on the NASA-Jacobson passenger acceptance matrix. With flight control law improvements, this difference will be futher reduced.
See "Blended Wing Body Design Challenges" by R.H. Liebeck (AIAA Paper 2003-2659) for some brief discussion and analysis.
Scott
Video screens. Yep, anything to avoid actual vision of actual reality.
I love to fly. I love to look out the window, endlessly, marvelling at all that there is to see, from murky clouds to endless ocean or land. It's a continuous miracle.
I have no interst at all in IFE. Just give me a window, and I won't move for hours. Promise.
I fear the electrochromic windows of the 787, complete with "manual over-ride for use by the flight crew" (FI, 26 Sept, page 61). I am very familiar with current "manual over-ride" which expressionless flight attendants now practice, as they lean across to the window to pull the shade down. I have to intervene physically to prevent this wordless over-ride. Yes, hard to believe, but I do intend to pass the whole night looking out. How many of the 300 other passengers saw the lights of the fishing fleets between Japan and Alaska? How many others saw the first colours of the morning? How many others saw the contrails and black dot of the aircraft passing us in the opposite direction at a fantastic closing speed?
I guess we need to have a choice on the ticket and seat selection: viewing or non-viewing section.
Jim Johnson
Jim's comments about the B787 strike a chord with me....I'll avoid the aircraft (if I can) once it is apparent that I will be denied the opportunity to exercise my preference to look out of the window rather than either watch the IFE or sleep. And if I can't avoid flying in it, the cabin crew had better be prepared for a lively debate on the subject. I won't be the only one voting with my feet over this issue. Boeing be warned.
Andy Coupland
I don't think distance from the centre-line of the a/c should be much more of an issue than, say, for passengers at the front or rear of any currently operating aircraft as it pitches up for climb, or down for descent...particularly in these days of 'fly-by-wire' technology.
The 'less-discussed' problem, as I see it, may in fact be the relative fuel-burn at different speeds of such a configuration. While fuel savings of up to 27% over conventional 'tube-and-wing' aircraft are touted for the BWB, will the larger forward-facing cross-section of the spanloader mean that these savings are only realised at speeds of about M0.70-75, with less impressive economics at M0.82-85, the speeds at which current aircraft operate ? Will the infrastructural investment required to adapt airports, maintenance facilities, etc then be considered worthwhile, in light of these more marginal economics?
John Caffrey
Big video screens networked trough the cabin(s), should be able to provide enough visual clues to avoid problems; and we go trough all that already any time the aircraft we are in manoeuvres whilst we are busy not looking outside.