Max Kingsley-Jones/LONDON
When Airbus Industrie launched its four-engined fly-by-wire A340 family in June 1987, it was the first all-new long-range widebody for a generation, and seemed to catch Boeing on the hop. The McDonnell Douglas DC-10-derived MD-11 provided the only competition for the A340 for several years as Boeing seemed preoccupied with its "767-X" project.
Whether this was a ruse on Boeing's part to lull its rival into a false sense of security is open to conjecture, but Airbus vice-president strategic planning Adam Brown concedes that, when planning the A340 and twin-engined A330, the European consortium assumed that the competition would be a 767 derivative. When Boeing launched the all-new 777 twinjet in 1990, it became clear that the Seattle-based manufacturer had taken a long and detailed look at the market. Boeing had obviously formulated a family plan for its new aircraft from the day of the launch, with stretched and longer-range models over the horizon.
Boeing's 777 family approach stole the initiative from Airbus, and the new twinjet proceeded to infiltrate A330/A340 customers in the Asian market, as well as landing its own clients. While Boeing had a 380-seat 777, the -300, on the drawing board from the start, Airbus seemed reluctant to commit to a larger A340 that would enable it to compete head-on.
The European consortium was constrained by the engine thrust growth available from the A340's CFM International CFM56s and undertook some simple stretch studies under the "A340-400X" project name. In 1991 the studies crystallised around a 12-frame (6.3m) stretch, which boosted three-class capacity to around 340 passengers. With the constraints of the existing -300 wing and little more thrust available from the CFM56-5, however, the-400X would have suffered a range penalty of around 2,800km (1,500nm). Ironically, seven years on, it is Boeing which is now struggling to stay competitive as 777 engine manufacturers are reluctant to invest in increasing thrust much beyond 100,000lb (445kN).
With the long range market clearly being driven by payload/range performance, Airbus quickly decided that a larger new engine in the 40,000- 45,000lb-thrust bracket would be needed and so the consortium sought bids from competing manufacturers.
Airbus had started a formal process of soliciting input from potential operators in 1995, with the first meeting of a customer focus group. The second focus group meeting occurred in early 1996, followed by two more during 1997. A fifth will take place during the Farnborough air show this month. Around 15 airlines are usually represented, including both existing and prospective customers.
One of the first focus group-inspired changes was the decision to study a larger, 20-frame (10.6m) stretch of the A340, says vice-president marketing Colin Stuart. "Then British Aerospace came up with a modified wing solution incorporating an insert and providing 20% more area," says Brown.
CAPACITY AND RANGE
The 20-frame stretch, combined with larger wing and higher thrust engines "-provided the best balance of capacity and range", says Stuart. Dubbed the A340-600, the new model can carry some 380 passengers over similar ranges to those of the A340-300. At about the same time, Airbus also began examining a model slightly larger than the 295-seat A340-300, but with the -600's bigger wing and engines. The outcome is the ultra-long-range 313-seat A340-500.
General Electric signed a six-month exclusive agreement in April 1996 to study the development of a new engine for the stretched A340. By now, Airbus was looking for an engine in the 50,000/60,000lb-thrust bracket. The talks fell through in early 1997 when the two organisations could not agree on key issues, including commercial terms. After considering an offer from Pratt & Whitney, Airbus selected Rolls-Royce to provide its Trent 500 - a derivative of the Trent 700/800 - announcing the agreement at the Paris air show in June 1997, when the A340-500/600 programme also received the commercial go-ahead. Although the deal with R-R is effectively exclusive in the medium term, P&W continues to discuss the possibility offering an engine of the PW4000 on the A340-500/600 with Airbus.
| AIRBUS 340-500/600 | ||
| SPECIFICATIONS | ||
| Dimension | -500 | -600 |
| Overall Length | 67.8m | 75.3m |
| Wingspan | 63.5m | 63.5m |
| Height | 17.8m | 17.8m |
| Wing area | 437m2 | 437m2 |
| Maximum take-off | 365t | 365t |
| Maximum landing | 236t | 254t |
| Operating empty | 170.4t | 177t |
| Maximum payload | 43.3t | 55.8t |
| Fuel capacity | 213,120litres | 195,620litres |
| Powerplant | Rolls-Royce Trent 553 | Rolls-Royce Trent 556 |
| Thrust | 53,000lb | 56,000lb |
| Three class | 313 | 380 |
| One class | 440 | 485 |
| Optimum cruise speed | Mach 0.83 | Mach 0.83 |
| Maximum cruise speed | Mach 0.86 | Mach 0.86 |
| 15,750km (313 pax) | 13,900km (380 pax) | |
| Source Airbus Industrie |
The Trent 500 will be offered at thrust ratings between 52,000lb and 60,000lb. It incorporates the 2.47m-diameter fan, case and accessories of the A330's Trent 700, with scaled intermediate pressure (IP) and high pressure (HP) compressors and the high-speed, low-loading HP and IP turbines of the Trent 800. These elements are combined with an all-new high-lift low pressure turbine.
Although a full launch was not announced at Paris, the Airbus board's amber light cleared the way for the aircraft to be offered to airlines. By the time of the full commercial go-ahead last December, commitments stood at around 100 aircraft from seven customers. The programme will require an investment of some $2.5 billion, and the consortium is aiming to capture at least half of the 1,500 sales forecast for the category through to 2010.
LATEST REQUIREMENTS
During 1997, the baseline specifications were tweaked to meet the latest requirements of potential customers, and slight increases in maximum take-off (MTOW), maximum landing and zero-fuel weights yielded a 370km increase in range. At that time, Airbus was battling against Boeing, offering the 777-200X to provide Singapore Airlines (SIA) with a 206-seat aircraft with a range of 16,260km to fly non-stop between Singapore and Los Angeles. The tweaks clearly achieved their aim, as SIA confirmed its selection of the A340-500 in May, with an order for up to 10 aircraft.
The A340-600 is some 10.6m longer than the -300 and will be able to carry 380 passengers (three-class) over 13,900km, some 370km further than today's A340-300. The A340-500 has a slightly stretched -300 airframe (to balance the enlarged wing) and extra fuel capacity, creating a 313-seater with a range of over 15,750km. The -500 will be powered by the baseline 53,000lb-thrust Trent 553, while the -600 will have the Trent 556, rated at 56,000lb.
Both variants are offered with a baseline MTOW of 365t, some 90t greater than the heaviest -300 now available. To cater for the increased weights, Airbus has replaced the A340's existing twin-wheel centre main gear with a four-wheel unit. The consortium revised the centre gear installation after input from the CFG, which wanted more cargo space. The gear had originally been designed to retract aft, but will now stow forward, enabling the rear cargo hold to be extended forward and providing space for two additional pallet positions.
Michel Delort, A340-500/600 chief project engineer, says that Airbus is working to finalise the systems design on the new models, a task which should be concluded by year-end. "The focus group meetings are running in parallel with working groups and design/build teams to ensure that we have a 'mature' aircraft at entry into service. Specific topics include systems, flight operations, structure, cabin, cargo and ground handling and engine nacelles," he says.
Delort says wing aerodynamic design was frozen in January 1997. Since then Aerospatiale, BAe and Daimler-Benz Aerospace Airbus have been undertaking windtunnel testing in France, Germany, the Netherlands and the UK as the design is fine-tuned. "The nacelle inlet and pylon shape have been finalised and the design will be frozen later this year," says Delort. He adds that installation drag has been checked in the windtunnel at France's ONERA research establishment, confirming performance targets.
A landmark was reached in June, with the selection of Sextant Avionique to supply active matrix liquid-crystal displays for the new A340s, which replace the Sextant-supplied cathode ray tubes that are standard on the current models. The latter part of this year will see more equipment selections being finalised, says Delort.
To handle engine-out conditions with the more powerful Trent 500s, the new models will incorporate the larger fin that Airbus developed for the A330-200 twinjet. The new fin has an enlarged torsion box, a 1m tip extension and a 6% increase in rudder chord. The tailplane will also be larger and will be made entirely of carbonfibre reinforced plastic, unlike the current unit which is a carbonfibre/aluminium hybrid.
The A340-500/600 will include extensive use of new structural materials. For example, the existing metal rear pressure bulkhead will be replaced by a unit constructed entirely from carbonfibre, while the engine pylons, which are now made of steel, will be made mostly of titanium. New lightweight materials will also be used in the wing, to enable Airbus to meet its weight targets for the aircraft.
WORLD'S LONGEST
The 10.6m fuselage stretch boosts the A340-600's overall length to over 75m, which will see it take from the Boeing 777-300 the mantle of being the world's longest airliner. Although the Messier-Dowty landing gear will be modified for the new variant, it will not be any taller. Delort says various solutions are being examined to avoid tailscrapes: "The long fuselage does bring some constraints, and solutions being studied include a 'smart system' with a rotation law built into the flight control software to limit the body angle during take-off, or warning devices on the flightdeck." Delort adds that the final selection of a solution will not be made before next year.
R-R will begin ground runs of the Trent 500 in the second quarter of 1999, while engine certification is expected at the end of 2000. Delort says that Airbus intends to undertake some flight testing with a Trent 500 installed in place of one of the CFM56s on the A340-300 development aircraft, before the consortium flies the first -600.
| A340-500/600 CUSTOMER LIST - AUG 1998 | |||||
| ORDERS | OPTIONS | ||||
| 500 | 600 | 500 | 600 | TOTAL | |
| Air Canada | 2 | 3 | 10 | 15 | |
| Egyptair | 2 | 2 | 4 | ||
| Emirates | 6 | 6 | 12** | ||
| Eva Air | 6 | 6 | 12** | ||
| Lufthansa | 10 | 10 | 20 | ||
| Singapore Airlines | 5 | 5 | 10* | ||
| Swissair | 9 | 10 | 19 | ||
| Virgin Atlantic | 8 | 8 | 16 | ||
| Total | 19 | 32 | 17 | 40 | 108 |
| *customer undisclosed by Airbus Industrie | |||||
| **commitment (firm contract not signed) | |||||
Fabrication of the first A340-600 began in July, with metal being cut for the wing centre section. Final assembly of the first -600 will begin at Aerospatiale's plant in Toulouse in the second quarter of 2000, and will be integrated with that of the existing A330/A340 models in the purpose-built Clement Ader assembly hall. Delort says that the current wing and fuselage assembly/mating stations will not be able to accommodate the new models, so a second example of each will be introduced specifically for the -500/600 models. These will also be able to accept the existing A330/A340 variants, however. Airframe equipping will be undertaken in the existing parallel stations, adjacent to the mating positions.
The first A340-600 will be flown in early 2001, followed about five months later by the first -500. Type certification of the A340-600 as a derivative of the existing family is scheduled for early in 2002, to enable deliveries to launch customer Virgin Atlantic Airways to begin in the first quarter. First deliveries of the A340-500 will follow shortly after.
Airbus says the monthly production rate for the -500/600 will reach four units in 2004, plus an additional three a month of the existing A330/A340 models. Airbus sees the new variants as complements, rather than successors, to the existing A340-300. It says that it expects the -500/600 to have a positive impact on sales of the existing aircraft.
Although the 380-seat Airbus will come to the market some four years after its Boeing rival, Airbus believes the design and performance of the new aircraft will more than compensate. "We are competitive with the current 777-300 on seat-mile costs, and can offer 1,000nm [1,850km] more range," says Stuart. He adds that, compared to the proposed long- range 777-300X, "-we have a massive take-off performance advantage".
ULTRA-LONG-RANGE RIVAL
Airbus claims that the 365t MTOW A340-600 requires a 3,260m (10,700ft) take-off run at sea level, ISA+15°C, while in similar conditions the 777-300X, equipped with 104,000lb-thrust engines, needs 3,800m. The A340-500 has a similar advantage over its ultra-long-range rival, the 777-200X, Airbus says. Neither long-haul 777 model is yet launched, and they are unlikely to enter service earlier than the new Airbuses.
Although it is a devoted fan of the twinjet concept in certain conditions, Airbus questions the practicality of extended range twin-engined operations (ETOPS) on ultra-long-range flights, and sees its "ETOPS free" four-engined design as the only solution. "ETOPS has expensive pitfalls that can cause enormous delays for passengers and can add substantially to operating costs," says Stuart.
He argues that a long list of difficult conditions must be met to undertake an ultra-long-haul ETOPS flight with, for example, a series of alternate airports along the entire length of the route having to be open to Category 1 standards. "Alternatives on polar and transpacific operations generally do not have these characteristics," he says.
Although Airbus is known to be studying even greater performance capabilities for the new family, Delort says that growth studies will not be firmed up until the first aircraft has been flown. "We have identified possible developments, but we want to fly and test the baseline aircraft before deciding," he says. BAe says the A340-500/600 wing structure has the capability for higher weights which, combined with higher thrust versions of the Trent, would provide increased payload/range ability.
ENLARGED WING IS KEY ELEMENT IN NEW FAMILY
In parallel with the studies of larger A340 versions, Airbus wing designer British Aerospace began to look at ways of increasing the wing's lift performance. BAe says that studies initially centred upon simple trailing edge modifications which, although increasing the wing's lifting capability, did not provide for increased fuel capacity. The company then studied wing inserts and root extensions before deciding in favour of the former in early 1996.
BAe says it decided on the insert solution as it provided the benefits of increased area and greater fuel capacity, while enabling the leading and trailing edge components to be common with the existing A340 wing.
The basic design of the new wing was finalised in January 1997. It incorporates a three-frame (1.6m) wingbox extension combined with a tapered insert, along with 1.6m wingtip extensions and the existing 2m-span canted winglets. The modification increases wing area by 20% which, combined with the larger centre section, boosts fuel capacity by 38%. The A340-500 features an extended centre section fuel tank, increasing its fuel capacity compared to the -300 by a massive 50%.
Although the tip extension requires a longer seventh slat, the two-position leading edge slats will otherwise be common with those on the existing aircraft, as will the single-slotted trailing edge flaps, although the deployment angles may be altered slightly.
The tapered insert provides a slight increase in wing sweep, from 30° to 31.5°, and greater chord without any significant increase in depth, which BAe says will yield a slight increase in cruise speed. Airbus expects that Mach 0.83 will be achievable in all conditions, compared to the current wing's M0.82 design cruise speed.
The wing is the largest ever produced for a civil aircraft in Europe. BAe has invested some £70 million ($113 million) in its manufacturing facility at Chester, with a purpose-built line being created.
Source: Flight International
