Airbus opts for larger wing on A350-1000 through trailing edge extension
By Max Kingsley-Jones
Airbus is working to reach the design freeze for the largest A350 variant, the -1000, in the middle of this year and has revealed that the stretched aircraft will feature a slightly larger wing the -800/900 models.
The 369-seat -1000, which has an 11-frame stretch over the -900, is due to enter service at the end of 2015. A separate A350-1000 design team was set up in 2009, headed by the XWB programme's deputy engineer Alain De-Zotti, which is examining trade-offs for the design, says chief engineer Gordon McConnell. Detailed definition is due to be completed at the end of 2011.
Airbus's operational requirement targets for the -1000 include keeping the approach speed to 150kt (277km/h) at maximum landing weight, compliance with London's QC1 noise requirements for arrival and QC2 for departures, and the capability to reach an initial cruise altitude of 33,000ft (10,000m) in less than 30min.
"With these parameters we were able to do the work to design the wing, and we found that with some changes to the trailing edge we can meet all these requirements," says McConnell.
The wing will feature a trailing-edge extension increasing its area by 4%, which McConnell describes as "quite a big change because it extends the high-lift devices and the ailerons, making the chord bigger by around 400mm. We've been able to optimise the flap lift performance as well as gain more performance in the cruise."
The -1000 design team will work this year to finalise the changes over the -800/900, with some other less significant trade-offs to be completed on the configuration. Windtunnel tests will be run this year based on the enlarged wing, covering both performance and loads. "This will allow us to size the structure properly, which will give us a good idea on the weight delta of the aircraft," says McConnell.
Source: http://www.flightglobal.com/articles/20 ... -edge.html - Flight International
Airbus devises plan to compress A350 flight-testing by three months
By Max Kingsley-Jones
Airbus aims to meet the A350's mid-2013 service-entry target by compressing the flight-test programme into 12 months, after revealing that it has burnt up some of the development programme's " buffer".
The A350-900's 12-month, 2,600h flight-test programme will begin in mid-2012 with the maiden flight of the first of five development aircraft.
The date for the first flight has slipped by three months because of development delays in the aircraft's structural design, but Airbus is confident it can meet the mid-2013 service entry target for launch customer Qatar Airways by reducing the original 15-month test programme by three months.
"We've got five aircraft in the flight-test programme - which is more than we usually have," says A350 chief engineer Gordon McConnell.
He says that the original 15-month plan had been generous - some customers had questioned why it would take Airbus so long - and the airframer has been running projects with its flight-test and engineering teams to devise ways of compressing it.
One example is the flight manual process, says McConnell: "In the past we've done the aerodynamic testing to freeze the configuration, then the performance testing, and then built the flight manual. We've been working to make that a more concurrent effort."
The flight manual will now be built ahead of flight testing and will then be checked during flight-testing, with adjustments being made when necessary. "We've been able to save quite a lot of time on that critical path," he says.
The first two A350s to fly (MSN001 and 003) will be heavily instrumented. MSN001 will undertake all of the flight-envelope opening at the beginning of programme, to enable the aerodynamic and flight-control configurations to be frozen.
"MSN003 will be more devoted to performance and systems testing, but the two aircraft will be interchangeable because they have the same instrumentation," says McConnell.
The third A350 to fly will be MSN002, which will have a cabin installed. "We'll fly that early in the programme so we can do proper operational testing on the cabin and deliver a mature aircraft to customers," says McConnell.
MSN004 and 005 will undertake operational tests and extended twin-engine operations trials towards the end of the programme, with Airbus planning to have up to four of the first five aircraft airborne before end-2012.
Source: http://www.flightglobal.com/articles/20 ... three.html - Flight International
A350 launch customer Qatar Airways unconcerned by three-month first flight slip
By Max Kingsley-Jones
Airbus A350 launch customer Qatar Airways is unconcerned about the three-month slip in the twinjet's first flight schedule, believing that the buffer built into the test programme should ensure its deliveries remain on track.
Airbus confirmed to a gathering of existing and potential customers in Nantes during its recent fifth-programme progress review that final assembly and the maiden flight of the first A350-900 have slipped by three months to the third quarter of 2011 and mid-2012, respectively, due to issues that have cropped up during the design of the airframe's carbonfibre structure.
However Airbus remains committed to the mid-2013 first delivery to Qatar Airways, which has 80 of the Rolls-Royce Trent XWB-powered twinjets on order.
"We are currently relaxed about the slippage," says the airline. "The three-month delay is easily accommodated within the flight-test timescale, which has been reduced from the very long 15 months originally planned, to 12 months, which is the industry norm."
The programme's chief engineer Gordon McConnell says the airframer knew it had "a good buffer" built in to the original 15-month flight-test programme and had been looking at ways to do it quicker.
Programme manager Didier Evrard says that as the detailed definition of the baseline A350-900 progressed last year and Airbus prepared to begin machining the first parts, "I had to give a bit more time to our structure designers for deeper validation".
He says that the reason for Airbus's caution was that the "process for development of structure in composite is really different [to metal] - you cannot start machining the part and then improve the design".
Four areas of the design were affected: the airframe sizing, the wing-root joint, the fuselage's electric structural network (which helps the conductivity of the carbonfibre fuselage) and the fuselage damage tolerance. The first two of these have been resolved and the fix approved, while the others have a solution under validation.
The slip has already ha an impact on production, with the first material cut on the A350's horizontal cruciform sliding from November 2009 until 5 March this year, which has also pushed back the assembly of the centre wing box by three months to mid-2010.
Evrard says that the A350's systems development is "roughly" on schedule but having consumed margin on structures "it is important that we secure and find other buffers in the phases to come".
However, he is optimistic that the schedule can be met: "It's not going to be easy, but we have a good chance to be there or thereabouts."
Source: http://www.flightglobal.com/articles/20 ... light.html - Flight International