Here comes the Boeing 797?

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19 years 10 months

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sferrin, I dont have the time to walk you through why people make the decisions they do, safe to say, better informed than you have things in hand. I think by 'British thing' you mean the Vickers VC10. seahawk, I'm not sure how the idea would scale down to 737 size.
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14 years 6 months

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sferrin, I dont have the time to walk you through why people make the decisions they do, safe to say, better informed than you have things in hand.
So far none of those decisions have included being able to punch off the engines so what makes you think it is a wise idea? :p

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19 years 10 months

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maybe I should just bow to your armchair expertise? perhaps you could come and do my job for me?
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13 years 10 months

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Interesting.....but........Boeing is commited to the 747-800..........and a BWB is one HUGE leap in equipment.....not sure if the public (or airlines ) will go for it.
Yes i agree they are planning way too far ahead why not just improve on what they have until they think they think its ready to be designed/manufactued

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14 years 3 months

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The real driver behind this revival may well be the increase in fuel prices...as the BWB does promise some interesting % increases in fuel economy...certainly sufficient to make the capital investment worth at least a study. If double digit % reductions in fuel consumption are possible, no matter the scale of the aircraft then the military will be interested as it may give payload increases and if future civil versions may keep user prices at the current low levels then passengers will not 'mind' at all...afterall do you remember the mindset when the twin aisle 747 came in..'who would want to sit away from a window?' according to them nobody would want to fly in it.. or escape from the upper deck and so on and so forth...solutions will be found.. whether or not they are acceptable is the challenge the designers face. Explosive bolts and jettisoning large parts of the airframe/ engine pods are, to date, fairly incompatible with civil aircraft and operations into and out of the currently located civilian airfields.....not to say that its not going to happen....but not on the foreseable future's horizon. ;) The military freighter may indeed be a more viable application. Also measn the funding is effectively a Government funded process..allowing civilian spin-offs in the future.. sound familiar?

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19 years 10 months

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Yep, peoples perceptions will change, it'll attract some people because it is novel, but you have to cater for the general populace and I think we all agree that they can be a tricky bunch! The idea of jettisoning the rear fuselage has been seriously considered in reports, having spoken to people in the know, simply because its a fast way out, and its better (aerodynamically, and structurally) than putting doors in the leading edge!. We are now starting to see that aerodynamic improvements available with today's 'standards' is yielding smaller and smaller increases as we refine our work and methods more and more. This is going to happen to engine technology aswell, as time goes on so a point will be reached where, unless somthing drastic is done, no further competitive advantage can be gained. This is true of aerodynamics, engines, and structures. The current rules, whilst providing safety for users are hindering the innovation of the aerospace companies in my opinion. As an example the A330 has a centre spar which forms a tank boundary, besides its main structural purpose. This boundary is placed in such a way that it cannot be penetrated by a fan blade, should one come loose, in order to ensure that only one tank is ever damaged by penetration through the covers. This is true of 'other' aircraft also. Today we have (admittedly large) engines which come fitted with ballistic blanket protection as standard which has been proven to contain a burst disk event. So, knowing that, we could remove the central spar, slightly redesign the front and rear spars, and save ourselves some weight or increase our range (take your pick). Problem: the rules formed in the 50's say that the tanks must be seperated as a matter of redundancy............so we now have uneeded multiple redundancy from rules which are not in-line with current thinking...........and an advantage going to waste! coanda
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14 years 6 months

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maybe I should just bow to your armchair expertise? perhaps you could come and do my job for me?
I have a better idea. How 'bout you stop whining and tell us why nobody designs their planes to be able to jettison the engines if it's such a great idea.

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14 years

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Picture the scene at the FAA certification review;- Boeing 797 Man "This is our latest blended wing mega airliner.... ain't she pretty" FAA Man "There's only one thing that troubles us, um..., if you are going to sit the pax in the wing, then where do you put want normally goes in the wing?" Boeing 797 Man "Darn it! we hoped you would not spot that!" FAA Man " your not seriously proposing to sandwich the PAX between the fuel tanks are you?" Boeing 797 Man "It's really not that bad .......... fuel tanks don't ever leak that much........ and I know, we promiss it won't every crash!"

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19 years 10 months

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Vega, I'm not up on the effects of crashes, do you know how many survivable crashes have had ruptured fuel tanks? I wonder what proportion of the 'fuselage' would be taken up with the cabin interior? I can see that it would probably be able to have dual use, carrying both respectable passenger and freight payloads in upper and lower decks. Having the fuel in-line or above the cabin deck would need some innovative thinking. Besides this, fuel systems can be made to vent between wings during lateral manouveres, and during some failure cases. I wouldnt like to see systems pipes running under the cabin deck, between wings! sferrin, 1.No aircraft has had between 2 and 4 T7 sized engines hanging off the end of the tailplane. If one/some engines were to stop, a significant amount of drag, above the CG would develop. This would change the aircraft trim, moving the CG aft, an aft CG reduces the stability of the design. The control system would, of course, be required to balance these forces aerodynamically. You either make this engine failure case a control system design criteria in the overall aircraft design, driving positions/sizes of control surfaces, and engine placement, or you try to be innovative. Jettisoning the engine pods, to my mind IS innovative. 2. Should the aircraft have a succesful ditching or forced landing we have the problem of getting people out. Given that the aerodynamicists have successfully argued that disturbing the leading edge is worse than the cost of putting the exit doors/sections at the back, we have to put the doors at the rear. The following possibilities exist.... a. passengers must wait until the engines have run down, ensured that there are no fires, or ruptured pipes and that there is no debris in the way of clear exits, then they can exit. b.the engines are still turning and a fan disk disintegrates, spraying the cabin with hot molten metal (should the metal puncture ballistic protection). c. same thing applies to a ditching and you have the added urgency of a sinking, which will be nose down, ensuring that passengers will need to climb to the exit if the evacuation should need to be delayed. d.options a to c wouldnt happen in real-life(tm) because everyone would be scrambling for the nearest exit. jettisoning a rear section of the aircraft, and it wouldnt neccessarily have to include the engine pods, provides ample exit room. Of course, these are all options, but it is intersting to play with the idea's to see what comes of them......for example, how do you get the fuel from the tanks to the engines?? in current aircraft its basically 3 metres of pipe from tank to combustor, but in a BWB there's allot of (uphill!) pipe to consider......... coanda
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14 years 6 months

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Picture the scene at the FAA certification review;- Boeing 797 Man "This is our latest blended wing mega airliner.... ain't she pretty" FAA Man "There's only one thing that troubles us, um..., if you are going to sit the pax in the wing, then where do you put want normally goes in the wing?" Boeing 797 Man "Darn it! we hoped you would not spot that!" FAA Man " your not seriously proposing to sandwich the PAX between the fuel tanks are you?" Boeing 797 Man "It's really not that bad .......... fuel tanks don't ever leak that much........ and I know, we promiss it won't every crash!"
I think they were planning on putting it below the passenger compartment. . . I hope. No idea where the luggage would go. The thing is, with that kind of configuration you have a LOT of volume to work with. Luggage could go down the center below the floor with the fuel in the outer area.

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14 years

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I wonder what proportion of the 'fuselage' would be taken up with the cabin interior? I can see that it would probably be able to have dual use, carrying both respectable passenger and freight payloads in upper and lower decks. Having the fuel in-line or above the cabin deck would need some innovative thinking. Besides this, fuel systems can be made to vent between wings during lateral manouveres, and during some failure cases. I wouldnt like to see systems pipes running under the cabin deck, between wings! coanda
Just where the fuel goes in a blended wing may be one of the fundamental cert issues... in such an aircraft volume is at a premium, and the cabin/baggage space takes up a lot of that. Hence to get the required fuel volume, pretty much every awkward little remaining cavity needs to be full of fuel...... even the space above the Pax cabin. Just for the record the first proposal for this type of blended wing aircraft that I've seen came from Handly Page in the mid 60's.

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19 years 10 months

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I guess it all comes down to relative sizes.........i.e. what size will the 'wings' be on this design? A330 ish? As you know Vega, the fuel in a wing is a very effective damper, and can prove quite useful in keeping loading under control, so I personally cant see them making empty wings, especially with all that volume going to waste..........you could put a cavity between the 'wings' and the 'fuselage' to create a safety barrier should there be a tank rupture in that area.