Design Notes: 787-9 lays the 787-10 foundation

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With two and a half years to go before ZB021, the first production 787-9, is handed over to  Air New Zealand at the end of 2013, Boeing is advancing forward on detailed design of the larger 250 to 290-seat Dreamliner, while it appears to be quietly laying the foundation for the third variant, the yet unlaunched 787-10. 
Up Weight Paves The Way
First, Boeing has again increased the maximum take-off weight of the 787-9, though it’s not entirely clear that the increase to 553,000lbs is driven entirely by regaining payload range capability due to an increase in airframe empty weight. Rather, one industry official indicates that the MTOW figure is be identical for the conceptual stretched 787-10. The increase actually appears to build a design bridge to the 787-10.
The same MTOW figures are indicative of structural similarity of the “simple stretch” -10, which hopes to fly 300 passengers a range of 6,900 to 7,000nm. If nothing else, the precedent for identical MTOW figures in Boeing stretches is found in the 777-200ER and 777-300, each with the basic takeoff roll weight capability of 582,000lbs.
While the 787-9 is starting to show signs of readiness for the -10, it still appears the larger jet is still “a long ways away” with hints of no earlier than 2015 and no later than 2017 starting to come in focus. 
A Question Of Fuel
Quietly tucked into the changing MTOW of the 787-9 is a further 44gal reduction in the aircraft’s fuel capacity. While not a very significant reduction when compared to the overall 33,384gal capacity, the amount now sits 144gal below the 787-8. This is a small figure, but 787-9 is set to deliver a 500nm range improvement over the -8 with more structure and payload flying on a wing with an identical wing planform as the -8. In a February 2010 interview, vice president of airplane programs, Pat Shanahan offered these thoughts on the optimized design flying farther on less fuel with more payload and structure:
That’s beauty of engineering, we’re not going to extend the length, add the same planform and decrease the range. So, the team, through understanding the performance of the -8, optimizing the configuration, they found a way to get the range and the extra payload.

The Cart Before The Horse
All this talk of the 787-9 and -10 is – first – entirely dependent on the 787-8 and its final certified configuration establishing a transparent baseline to work from. That final configuration, said Spirit AeroSystems CEO Jeff Turner in his company’s earnings call last week, will make the process of designing for the -9 considerably easier: 

I would say specific to the dash-9, as the dash-8 matures and nears certification, the dash-9 is a derivative off of that dash-8. So the more solid the dash-8 configuration is and becomes, the more straightforward the dash-9 derivative is. And that one is progressing very well.

Side-of-Body and Concept D
Before it was dismantled and relocated in pieces to the Boeing Boneyard in Everett, ZY997, the 787 static test airframe underwent a series of static tests with an updated side-of-body reinforcement modification designed for the larger -9 believed to be dubbed “Concept D”. It is believed that Boeing is focusing particular attention on the side-of-body join, further refining this terribly troublesome area for both weight and further growth.


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Fuselage Length & Program Cost
The phrase “simple stretch” tends to be a terrible misnomer, but is intended to convey the idea that an airframe’s modifications are generally limited to the fuselage and leverage capabilities already built into the smaller model, rather than optimize the airframe for equal payload and range performance. The 787-9 is made up of two 10ft stretches of Sections 43 and 46, placing all the structural growth into the center fuselage which is integrated in Charleston, already equipped with tooling for second model.
Industry officials say that design of the -10 is slightly smaller today than it was in 2007, but may still require a stretch of not just the 43 and 46 sections, but the 47 as well. The 2007 design stretched Sections 41, 43, 46 and 47. As the program seeks a low-cost investment to take on the Airbus A330-300, capital costs for tooling will undoubtedly be an important factor in keeping the investment low, stretching as few sections as possible is central to this say company sources. 
One potentially less obvious challenge is stretching the center fuselage so it still fits into the Dreamlifter. A 2008 diagram of the then-Global Aeronautica facility illustrated three types of centre fuselages on the pulse assembly line. Placing the full stretch in the center fuselage (preventing its air transport), could potentially make Charleston the base for the 787-10, saving tooling costs at Spirit and the nearby aft-fuselage fabrication facility.
Open Door For New Doors?
Saab North America, seeking to establish a presence in the US, identified the 787′s doors as a possible opportunity to expand its supplier relationship with Boeing. Saab already supplies the cargo doors on the 787, while Toulouse-based Latecoere supplies the Czech-built passenger doors. Latecoere recently signed a long-term supplier agreement with Boeing, but the doors have been a source of trouble these last few years, requiring significant rework after delivery. Latecoere doesn’t specify a variant in their announcement, but nor does Saab indicate on which model it hopes to expand its presence.
Renderings Credit Boeing

13 Responses to Design Notes: 787-9 lays the 787-10 foundation

  1. CM May 12, 2011 at 2:00 am #

    “through understanding the performance of the -8, optimizing the configuration, they found a way to get the range and the extra payload [in the 787-9]”

    This make perfect sense, which is why the A350 program schedule is so puzzling. Trying to deliver the A358 just a year after the A359 means Airbus cannot do for the A358 what Boeing is doing for the 787-9. Namely, Airbus will not be able to refine and optimize the A358 from flight test learnings gathered from the A359… A358 design loads will be complete before the A359 flight load survey can be completed.

    While this article highlights Boeing making some of their own good news for the 787, it underscores the fact Airbus is painting themselves into a corner where I fear the same thing will not be possible for the A350.

  2. SDFlight May 12, 2011 at 6:08 am #

    Boeing annouced the B787-10 atleast ten times just to cancel it two weeks later, thats why the customers choose the A350XWB. Airbus might not take all flight test results for the A358 but maybe there is an advantage in CFRP technologies from developments over the last 25years, just in case somebody in the US recognizes Airbus has much more experience in CFRP.

  3. Larry May 12, 2011 at 12:28 pm #

    So, the -9 gets more payload and range than the -8. Unless the fuel burn per hour of the -8 is a great deal less, what is the advantage of buying a -8 once -9 production begins?

  4. Anonymous May 12, 2011 at 2:36 pm #

    @Larry:

    There isn’t – remember Jon’s article about the pricing on 787-8′s? I’m not sure BA wants to sell any more -8′s than they have to at this point.

    Look at the 777 line; how many -200′s are sold v. -300′s.

  5. keesje May 12, 2011 at 5:45 pm #

    The 787-9 offering more range, capacity with less fuel capacity and the same wing. The miracle of engineering.

    If that becomes reality I would also trade in my 787-8s at the first opportunity.

    Lets not be romantic, then the 787-8 simply isn’t a very good aircraft.

  6. CM May 12, 2011 at 5:59 pm #

    Hey SDFlight, pay attention.  The world is a pretty complicated place and there’s lots you are missing. 

     

    1. Boeing has never “announced” the 787-10.  It has never been offered for sale to any airline.  It has never been an “airplane program”.  It has only ever been (and remains) a “study”, so it’s hard to understand why you think it has ever been cancelled even once, let alone 10 times.

     

    2. What you are claiming is that because Airbus introduced a CFRP vertical fin in 1974 (A300), and because Boeing did not introduce a CFRP tail on a commercial product until 1982 (ACEE 737), that somehow this is dictating the level of advancement and technology between the two OEM’s 30+ years later.  Frankly, that is a ridiculous perspective.  In 1981 Boeing was selected to build the CFRP wings and center section of the B-2 bomber – a far more complex CFRP structure than Airbus has ever developed.  Boeing was selected because they had more CFRP intellectual capital and capability than any other aerospace company.  That leadership remains today, and is reflected in the glaring differences in composite technology levels between the 787 and A350.  The 787 is truly an advanced composite architecture while the A350 is pure black aluminum.

  7. Tom May 12, 2011 at 6:34 pm #

    The decision to build the 350 with lower percentage of composite is no due to lack of knowledge.

  8. CM May 12, 2011 at 9:31 pm #

    @Tom

    I totally agree. The A400M is all the evidence you need to back up your statement; Airbus is more than capable of building an aircraft with far more composite content and far more advanced composite architectures than the A350… But they didn’t.

    The A350 design (like any other aircraft, 787 included) is a compromise between what is technically possible, what is cost-effective, and what can be reasonably achieved with acceptable program risk. The 787 program, with the advantage of more development lead time and less industry pressure (i.e. urgency), accepted greater risk and as a result has certain architectural advantages over the A350. An example is the use of one-piece barrels in the fuselage. The A350 program by necessity had to accept less risk and shorter development time. This is why the A350 fuselage architecture is less advanced. See page 25 of
    THIS AIRBUS PRESENTATION
    to see this stated directly from Airbus.

    Other factors influencing the A350 architecture include the requirement to place workshare with the constituent nations who provide RLI. This creates an additional consideration for Airbus, which in some cases artificially constrains the airplane design. Aluminum passenger and cargo floor beams from Augsburg are a good example of this. There are numerous global suppliers who could provide Airbus with CFRP beams. Instead, the A350 is unnecessarily saddled with something exceedingly undesirable to the airlines.

    For what it’s worth, Airbus claims a higher composite content in the A350 than Boeing does for the 787 (53% versus 50%, respectively). I’m not sure how that’s the case, given what appears to be much greater aluminum content on the A350 (forward cab, pax floor, cargo floor, etc are all aluminum on the A350 and CFRP on the 787), but it really doesn’t matter. Both will be good aircraft, and both will deliver significantly improved economics versus the 767, A330 & 777-200.

    Cheers!

    CM

  9. Seychelles Jack May 13, 2011 at 12:16 am #

    It seems that wing platform was ultimately designed for the 787-9. It does look a bit awkwardly oversized on the -8 model.. the 787-9 will be a truly beautiful aircraft, bringing the best out of the Dreamliner design.

  10. SDFlight May 13, 2011 at 6:07 am #

    Hey CM

    So far the Boeing marketing department would like to tell everybody, the truth is maybe a little different. Boeing claims the B737 is much more fuel efficient than the A320, the customers don’t agree and have other values. So i’m missing something? I don’t think so.

    We will see, if the B787-10 will ever come to live, first Boeing has to deal with some other problems. (B787-8, B747-8I, especially ordering numbers, and finally a competitor to the NEO)
    So far believe or not, it’s up to you.

  11. Guru Josh May 13, 2011 at 6:55 am #

    Looking at the vertical tail of the 787 and seeing those skin stringers with the stringer feet tacked to the skin with metal fasteners, I’d say we are definitely talking black metal here ;-)

  12. fred May 13, 2011 at 2:34 pm #

    so how did they do it (boeing – -9 compared to -8)? i doubt that much comes from the aero cleanup alone? and it is heavier, so it’s a puzzle.
    better engines on the -9?

  13. CM May 13, 2011 at 5:36 pm #

    Hi Fred.

     

    Because Jon highlighted both the reduced fuel capacity and added range on the 787-9, it’s easy to think they two are in some way related.  They aren’t.  Despite numerous weight, aero and engine improvements which will be introduced with the 787-9, it will not fly further on less fuel than a 787-8.

     

    In reality, the reduction in fuel volume on the 787-9 is not really a noteworthy item at all:  Airliners are seldom fuel volume limited.  Boeing and Airbus design their aircraft this way to make sure the limiting factor in how far an airplane can fly is never that the airline simply cannot get enough fuel onboard.  By making sure fuel capacity is not the limiting factor, aircraft range capability becomes a function of maximum takeoff weight – i.e. Is the structure capable of supporting the passengers and payload, plus enough fuel to fly this mission, and does the wing produce enough lift to get it off the ground?

     

    The added range on the 787-9 is partly a function of the improved aero, weight and engine performance (every lb of fuel you didn’t burn on the miles behind you is fuel you get to burn for the miles not yet flown), but mostly the added 787-9 range comes from added MTOW and the ability to load more fuel onto the airplane in the first place.

     

    Hope this helps!

     

    CM

     

    PS:  Josh, you are absolutely right.  Many aspects of the 787 remain black aluminum architectures and the vertical fin is a perfect example.  It just shows how much potential remains for future generations of composite aircraft!