The long-distance twin also comes with a choice of engine, now that Rolls-Royce is on the programme offering the Trent 1700 along with the GE GEnx-1A.
|A350: Improvements to the cruise speed, cabin, the crew rest area and simplification of the structure, landing gear and fuel tanks.|
Airbus, long a pioneer of composite materials in its aircraft, is erring on the conservative side compared with its rival in this market, the Boeing 787.” Where Boeing is committed to using some 60% composites in the 787 structure, the A350 features about the same in ‘advanced materials’ – made up of composites and aluminium lithium.
While carbonfibre reinforced plastic will be used in the A350’s wing and empennage, aluminium lithium will used in the fuselage.
A350 chief engineer Dougie Hunter says that the decision to use aluminium lithium in the fuselage is to enable the customer to better cope with accidental damage to the aircraft while on the ground.
“The fuselage does suffer from a lot of damage,” he says. “With all the servicing equipment that goes up to the aircraft, there is a tendency towards a significant amount of damage. With a composite structure, it can be repaired, but not as easily as metal.
“Aluminium lithium allows for easy damage assessment and standard procedures for repair.”
The issue of the proportion of advanced materials used in the A350 and the 787 – and where they are used – led to a verbal firefight between the two manufacturers earlier this year.
Boeing accused Airbus of breaking the industry taboo over raising safety as an issue in the development of each other’s products. Airbus retorted that its observations were not based on safety, but operational issues.
Advances in computing power have enabled the extensive use of computational fluid dynamics (CFD) to help design. CFD was used to reprofile the wing so that the onset of drag rise is delayed and raise long-range cruise speed from Mach 0.82 to 0.83 and economic cruise speed to M0.84.
A total of 8t in weight savings have been made from a number of initiatives, which include the use of advanced materials, redesigned wing fuel tanks and the design of simplified landing gear. The stiffness of the composite wing has allowed the centre spar to be taken out and a reorientation of the ribs made.
The aircraft’s nose has been reprofiled to meet the demands of customers wanting a greater level of comfort in the forward crew rest area. Originally located behind the cockpit area, Airbus moved it to the avionics bay under the cockpit to free up more space in the passenger cabin. In addition, in security-conscious times, it was considered a safer option allowing flightcrew to move from cockpit to rest area without entering passenger space.
By reprofiling the nose, the height of the forward crew rest area has been increased to 1.75m (5.7ft). The change also enables Airbus to scrap an earlier plan to equip the aircraft with a longer nose landing gear leg.
Hunter says: “We had adopted the longer leg to give the A350 a level standing position on the ground, but the reprofiling enables us to have a lower attachment point to achieve the level attitude with existing leg length, although the gear will be all-new.”
Larger cabin windows and wider seats are designed to give the A350 passenger appeal. The popular external cameras, enabling in-flight progress to be followed on seatback screens, will be transferred from the A330/A340 models to the A350.
The design team aims to give even the tallest passenger more headroom when entering or leaving seats by the better integration of stowage bins into the sidewall and ceiling panels.
Alan Pardoe, director product marketing A330/A340/A350 product family, says: “This is a cabin design with the passenger and the airline mind. Again, we have learned from the [development of] the A380. Airlines will be able to reconfigure it very easily: it will be easier to take things in and out.”
Source: Flight Daily News