The Aircraft


Fuselage

The new XWB fuselage has a constant width from door 1 to door 4, unlike previous Airbus aircraft, to provide maximum usable volume. The double-lobe (ovoid) fuselage cross-section will have a maximum outer diameter of 5.97 m (19.6 ft), compared to 5.64 m (18.5 ft) for the A330/A340. The cabin's internal diameter will be 5.61 m (18.4 ft) wide at armrest level compared with 5.49 m (18.0 ft) of the Boeing 787 and 5.86 m (19.2 ft) of the Boeing 777. It allows eight-abreast 2–4–2 arrangement in premium economy layout, with the seats being 49.5 cm (19.5 in) wide between 5 cm (2.0 in) wide arm rests. Airbus says that the seat width will be 1.3 cm (0.5 in) greater than a 787 seat in the equivalent configuration. In the nine-abreast, 3–3–3 standard layout, the XWB's seat width will be 45 cm (18 in) which will be 1.3 cm (0.5 in) wider than the proposed equivalent seat layout for the Boeing 787. A ten-abreast high-density configuration is also available.

Wings

The A350 features new all-composite wings that will be common to the three proposed variants. With an area of 443 m2 (4,770 sq ft) it will be the largest wing ever produced for a single-deck widebody aircraft. The geometric wingspan of 64.7 m (213 ft) is 4.5 m (15 ft) greater than that of the A330. This is the same span as the long-range Boeing 777-200LR/777-300ER, which has slightly less area. The wing tip will not sport the traditional wingtip fences, but instead are curved upwards at the final 4.4 metres (14 ft), "sabre-like". The new wing will have 31.9° of sweep, helping to increase typical cruise speed to Mach 0.85 and maximum operating speed to Mach 0.89.

a350-xwb-winglet



A new trailing-edge high-lift system has been adopted with an advanced dropped-hinge flap (similar to that of the A380), which permits the gap between the trailing edge and the flap to be closed with the spoiler.  The manufacturer has extensively used computational fluid dynamics and also carried out more than 4,000 hours of low- and high-speed windtunnel testing to refine the aerodynamic design, achieving the final configuration of wing and winglet on the "Maturity Gate 5" on 17 December 2008.

The wings are produced in the new £400M/46,000 square metres (500,000 sq ft) North Factory at Airbus Broughton, employing 650 workers, in a specialist facility constructed with £29M of support from the Welsh Assembly Government.

All three A350 XWB family members share the same wing planform – with a 64.7-metre wingspan, a total area of 442 sq. metres, and high swept leading edge. In addition the internal wing structure will be scaled to meet the specific requirements of each aircraft variant.  

Innovative concepts applied to the A350 XWB wing’s high-lift devices will reduce noise and drag while also improving the aircraft’s low-speed performance.  One of these innovations is the stream-wise deployment of trailing-edge flaps. On a traditional swept-wing jetliner, the outboard flaps extend at an angle to the airflow. For the A350 XWB, flap deployment is along the direction of flight – resulting in better lift efficiency and improved low-speed performance, while reducing aerodynamic-generated noise. 

Other A350 XWB wing enhancements include the adoption of a drop-hinge mechanism to improve the flap’s deployment kinetics, along with the introduction of a downwards movement for the upper wing spoilers to fill the gaps that occur when flaps are extended. In addition, the A350 XWB’s flight computer will perform in-flight trimming of the inboard and outboard flaps, creating a variable camber wing that adapts to different flight conditions.



Nose

The XWB's nose section will adopt a configuration derived from the A380 with a forward-mounted nosegear bay and a six-panel flightdeck windscreen. This differs substantially from the four-window arrangement in the original design. The new nose will improve aerodynamics and enable overhead crew rest areas to be installed further forward and eliminate any encroachment in the passenger cabin. The new windscreen has been revised to improve vision by reducing the width of the centre post. The upper shell radius of the nose section has been increased. The nose is likely to be constructed from aluminium but Airbus is currently running trade-off studies considering a one-piece carbon fibre structure. According to Gordon McConnell, A350 Chief Engineer, a carbon fibre structure would need titanium reinforcements for birdstrike protection, thus the aluminium structure is the best cost-wise.

A350xwb nose

Cockpit and avionics

The revised design of the cockpit dropped the A380-sized display and adopted 38 cm (15 in) LCD screens. The new six-screen configuration will have two central displays mounted one above the other (the lower one above the thrust levers) and a single (for each pilot) primary flight/navigation display, with an adjacent on-board information system screen. Airbus says the new cockpit will allow advances in navigation technology to be placed on the displays in the future plus flexibility and capacity to upload new software and to combine data from multiple sources and sensors for flight management and aircraft systems control. The A350 XWB will also feature a head-up display.

Airbus A-350 XWB  cockpit view



The avionics will be a further development of the integrated modular avionics (IMA) concept found on the A380. The A350's IMA will manage up to 40 functions (versus 23 functions for the A380) such as undercarriage, fuel, pneumatics, cabin environmental systems, and fire detection. Airbus says benefits will include reduced maintenance and lower weight because IMA replaces multiple processors and LRUs with around 50% fewer standard computer modules known as line-replaceable modules. The IMA runs on a 100-Mbit/s network based on the avionics full-duplex (AFDX) standard, already employed in the A380 instead of the Arinc 429 system on the A330/A340.

Engines / Powerplant

The Trent XWB family comprises two basic engines to power the three A350 variants. The baseline 370 kN (83,000 lbf) thrust version for the A350-900 will be derated to 330 kN (74,000 lbf) and 350 kN (79,000 lbf) for the -800, while an upgraded 432 kN (97,000 lbf) thrust version will power the A350-1000. The higher rating 432 kN (97,000 lbf) engine will have some modifications to the fan module - it will be the same 118-inch diameter but will run slightly faster and have a new fan blade design - and some increases in temperatures brought by new materials technologies coming from its research programmes. The basic 248t MTOW -800 will be offered with a 330 kN (74,000 lbf) sea-level-thrust rating, while the 279t MTOW option will have 350 kN (79,000 lbf) thrust. Airbus also plan to offer a 'hot and high' rating option flat-rated at 350 kN (79,000 lbf) at higher altitudes and temperatures which uses the full capability of the -900's 370 kN (83,000 lbf) thrust engine prompted by the operating requirements for Middle Eastern launching customers Qatar Airways, Emirates, and Etihad.

The Trent XWB will feature a 118-inch (300 cm) fan diameter and the design will be based on the advanced developments of the Trent 900 (Airbus A380) and Trent 1000 (Boeing 787). The Trent XWB may also benefit from the next-generation reduced acoustic mode scattering engine duct system (RAMSES), which is a noise-dampening engine nacelle intake and a carry-on design of the Airbus's "zero splice" intake liner developed for the A380. Engine thrust-reversers and nacelles will be supplied by US-based Goodrich Corporation.

The A350 XWB will feature a 1,268 kW (1,700 hp) Honeywell HGT1700 auxiliary power unit, which has 10% greater power density than the previous generation of Honeywell's 331 APU family. Honeywell will also supply the air management system: the bleed air, environmental control, cabin pressure control and supplemental cooling systems. The ram-air turbine will be supplied by Hamilton Sundstrand and will be located in the lower surface of the fuselage. The generator requirement for the ram air turbine is 100 kVA compared to 150 kVA for the A380.

Fuel and Hydraulics

Parker Hannifin will supply the complete fuel package: inerting system, fuel measurement and management systems, mechanical equipment and fuel pumps. The fuel tank inerting system will feature air-separation modules to generate nitrogen-enriched air that will be used to reduce the flammability of fuel vapour in the tanks.

Parker will also provide hydraulic power generation and distribution system: reservoirs, manifolds, accumulators, thermal control, isolation, software and new engine- and electric motor-driven pump designs. Parker estimates the contracts will generate more than US$2 billion (€1.5 billion or £1 billion) in revenues over the life of the programme.

Undercarriage

Airbus adopted a new philosophy for the attachment of the A350’s main undercarriage as part of the switch to a composite wing structure. Each main undercarriage leg is attached to the rear wing spar forward and to a gear beam aft, which itself is attached to the wing and the fuselage. To help reduce the loads further into the wing, a double side-stay configuration has been adopted. This solution resembles the design of the Vickers VC10.

Airbus devised a three-pronged main undercarriage design philosophy encompassing both four- and six-wheel bogies to ensure it can keep the pavement loading within limits. The A350-800 and A350-900 will both have four-wheel bogies, although the -800's will be slightly shorter to save weight. Both will fit in the same 4.1 m (13 ft) long bay. The proposed higher weight variant, the A350-1000 (and the A350-900R, which is being proposed to British Airways, with -900 size but with sufficient fuel capacity to allow nonstop London-Sydney flights) will use a six-wheel bogey, with a 4.7 m (15 ft) undercarriage bay. French-based Messier-Dowty will provide the main undercarriage. The nose gear will be supplied by Liebherr-Aerospace.

airbus-a350-gear