Superjumbo power

Tim Robinson gets an update on the progress of the engines that will power the Airbus A380, the Rolls-Royce Trent 900 and the Engine Alliance’s GP7200.

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By  Tim Robinson Published  October 1, 2005

|~|trent900.jpg|~||~|This year has been a momentous one for all involved in the Airbus A380 programme. A star-studded ‘reveal’ in January, followed by the historic first flight in April and the aircraft’s debut at the Paris air show have kept all eyes on the Toulouse giant’s progress towards entry in service. Running alongside the A380 airframe programme, however, has been the testing and development efforts of the two teams vying to supply the engines for this behemoth. Rolls-Royce, which counts Etihad among its customers, is ahead in terms of development at present, as the latest addition to its Trent family has already flown with the A380. The Engine Alliance, which comprises GE and Pratt & Whitney, is rapidly nearing this stage though, and it also has a lead in sales, which is due in no small part to having won a mammoth order from Emirates. The region’s third A380 customer, Qatar Airways, is yet to choose its engine supplier, and it does not plan to do so for at least another 12-18 months. Surprisingly, the engines that will eventually be used on the A380 are not be the most powerful ever used on a commercial aircraft. That title belongs to the monster 115,000 lb GE90-115Bs that power the Boeing 777-300ER. However, the A380 engines are unquestionably something special, particularly because of the need to meet a key requirement: quietness. Airbus’s early consultations with potential A380 customers showed that there was a strong desire to operate the aircraft in the QC2 departure criteria of London’s Heathrow airport, which is the strictest noise abatement regime in the world. This requirement was stipulated by Airbus to the engine-makers in 2000, particularly at the request of Singapore Airlines. The move complicated development work, but it also effectively future-proofed the A380 against the spread of noise restrictions worldwide. To achieve the desired noise levels both Rolls-Royce and EA opted to increase the size of the engine fan case to 116 in. This allows for a bigger fan, which is therefore slower turning and quieter. The success of these efforts was heard at Le Bourget, where the quietness of Trent 900s on the A380 was one of the major talking points. “A lot of people could not believe that it was a full rate take off,” notes Martin Johnson, vice president, communications, civil aerospace, Rolls-Royce. Although the spectators could hardly hear it, the A380 engines were producing thrust of between 70,000 and 75,000 lb. However, both suppliers’ engines will in fact be certificated at 81,500 lb of thrust, which gives room for growth for future variants. The 590 ton freighter variant will also need around 6500-7000 lb more power than its sister passenger airframe. Alongside being quiet and powerful, fuel efficiency was also a key part of Airbus’ criteria for the engines. The fuel burn for the airliner is designed to set new standards and Airbus claims that the A380 is more fuel efficient per passenger than a family diesel car. The A380’s huge economies of scale for fuel burn is one reason for this, but the other is the fuel efficiency of the contenders’ powerplants. Rolls and EA have taken different approaches to achieve this goal, but both manufacturers are confident that their engines will meet all of the criteria laid down by Airbus and its customers. ||**|||~||~||~|Roll-Royce Trent 900 Rolls-Royce was the first off the mark in the race to provide a powerplant for the then A3XX, signing an MoU with Airbus in 1996. Its offering, the Trent 900, is a logical development of the best-selling three-shaft Trent line of engines. The core, for example, is based on the Trent 500 and scaled up 10%. However, to meet Airbus’s requirements, Rolls has incorporated two pieces of new technology into the Trent 900. The first is a wide chord swept fan, which is the first to be used on a civil aircraft. These radical-looking swept fans were shown to provide optimum efficiency and airflow using new 3D computational fluid modelling techniques. Rolls’ second advance was to equip the Trent 900 with a contra-rotating shaft. This development, which was based on technology used in the engine-maker’s military lines, such as Pegasus, RB199 and EJ200, improves turbine efficiency and performance. It also means that fewer and lighter parts can be used. Proof of the virtues of contra-rotating shafts can be found in the engines for the Boeing Dreamliner, as GE has adopted the same approach for its GEnx powerplant. Rolls is also using one for its 787 offering, the Trent 1000. Alongside these innovations, however, the Trent 900 retains the three-shaft technology that is the engine family’s trademark. It is also a well-proven one, with Trents having now racked up more than 40 million flight hours around the world. Rolls also argues that the technology allows for lighter engines. For instance, the engine-maker says that its powerplants for the Boeing 777 are some 6-8 tons lighter in total than rival offerings, which translates into better fuel burn figures. “It is still our contention that [three-shaft] technology is typically better, as the Trents get larger,” adds Johnson. “It has allowed us to develop shorter, more rigid engines that are lighter in weight than the opposition,” he explains. Testing The new technology used in the Trent 900 and other minor tweaks to the design are now going through a testing process that has proceeded “extremely well,” according to Rolls. Switching the flight test focus from an A340 testbed to engines on an actual A380 did not throw up any major flaws. “[Results were] very much what was expected and in line with predictions, if not better,” says Johnson. At the time of writing, each of the four engines on the first A380 prototype had completed more than 275 hours of flight time during more than 90 flights. Rolls is also continuing to run a ground test ‘fleet leader’ powerplant to amass further data. The engine was officially certificated in October to a maximum thrust of 80,000 lb. However, it has actually run at 93,000 lb with no ill effects. It will also only enter service at 70,000 lb, so Rolls is confident that there is plenty of growth margin should a larger engine be needed for a heavier version of the A380 in the future. Customers Alongside its technology and experience, Rolls is always keen to emphasis its support credentials when selling engines. Its TotalCare power by the hour maintenance programme has been adopted by 60% of Trent 500 customers and nearly all Trent 900 operators. The programme is run out of an operations centre in Derby, England, which is manned 24/7, 365 days a year. It is able to provide realtime fault analysis for customers and predictive maintenance, which cuts costs for airlines and reduces downtime. In total, Rolls has been able to win orders from six A380 customers, comprising Singapore Airlines, Lufthansa, Qantas, Virgin Atlantic, Malaysia and Etihad. The Trent will also be used by the launch customer for the A380, Singapore Airlines, which, despite the well-publicised delays in the development programme, is still expected to receive its first aircraft before the end of 2006. ||**|||~||~||~|Engine Alliance GP7200 General Electric and Pratt & Whitney decided to form the Engine Alliance in 1996 in order to develop an engine for the then A3XX. They based their efforts on a powerplant that was designed for the proposed Boeing 747-500/600 — an aircraft that never left the drawing board. The engine, which was named the GP7200 — GP being an amalgamation GE’s and PW’s own engine designations — is a two-shaft design using hollow swept blades. It uses a core derived from GE’s GE90 married to the low pressure rotor and forward fan case from the Pratt & Whitney’s PW4000. Other partners in the programme include German giant MTU, France’s Snecma and Belgian-based Techspace Aero. The GP7200 differs from the Trent 900 in two important ways. The first is the use of a two-shaft design rather than the Trent’s three shafts. Also, while Rolls is only offering one version of the Trent 900, EA is developing two versions. The GP7270, which will be rated at 70,000 lb thrust, will power the A380–800 passenger version, while the GP7277, which will be rated at 77,000 lb thrust, will be used by the heavier A380 freighters. “When we designed the GP7200, we planned for growth,” explains Bruce Hughes, president of the Engine Alliance. “We are currently seeking certification at 76,500 lb of thrust and then we will certify the same engine at 81,500 lb in 2007. If needed, the basic GP7200 architecture can also accommodate thrust growth up to 84,000 lb,” he adds. EA asserts that the GP7200 has several advantages over the Trent. These include better fuel burn — 0.5% less over 6000 nm according to Airbus — better reliability, a two shaft design, which means fewer moving parts, and a proven fan blade. Testing To back-up these claims, the GP7200, like the Trent, has been undergoing an extensive test and development programme both in ground rigs and using GE’s 747 flying testbed. EA says it has completed 85% of the tests required for certification, which it is aiming to achieve this month or shortly after. The only three tests left for the engine are a 150 hour block endurance test, water and hail ingestion testing, and icing conditions. After certification, EA will then continue with the service readiness programme and prepare the engine for certification to 81,500 lb in 2007. Meanwhile, EA has also delivered the first flight test engines to Toulouse. Originally, the first flight of the GP7200-powered A380 was scheduled for next month. However, with the A380 now suffering delays, it seems that a more realistic date for the first flight will be in the spring of 2006. Customers Like Rolls, EA has an extensive worldwide maintenance network to support current and future GP7200 customers. Within the region, the most notable development is the Emirates’ GE engine test facility, which will be up and running in 2007. This support, along with the engine’s reliability, are key selling points for EA. “We have an extensive flexible service network for our operators… and we anticipate the first shop visit at about 3000 cycles (22,500 hours),” says Hughes. Customer support, says EA, was also an important factor in Emirate’s decision to select the GP7200 for its 43 A380s on order, which was a shock for Rolls-Royce. In addition, says Hughes, “the fan blade reliability and performance was a big selling point, as well as the two-spool design, which offered lower maintenance costs.” The latest customer for the GP7200 is Korean Air, which ordered 23 engines worth $300 million for the five A380s it has on order, in June. EA is therefore closing the gap on Rolls in terms of customers, as it now has five compared to the UK company’s six. However, EA is well ahead in terms of the numbers of engines sold, due to the Emirates’ mammoth order for 43 units. This deal alone accounts for more than half of all the GP7200 ordered so far. In total, EA has firm orders for 320 engines, valued at $4.1 billion.||**|||~||~||~|Conclusion Rolls-Royce and EA will continue to battle it out for engine sales to A380 customers, starting with the five airlines that have ordered the plane but not yet selected a powerplant. EA is also looking to unseat Rolls at Singapore Airlines, as the carrier has issued an RfP for 15 more very large aircraft. This deal may replace the 10 Trent-powered A380 that the airline has on option. This attempt to unseat a rival could also be harbinger for the future of the A380 engine market, particularly now that the widespread use of power by the hour deals makes it easier for airlines to operate different engine types. Of course, engine-makers always attempt to outdo each other when an airline orders more aircraft, but the limited size of the A380 market is likely to make the competition in this sector even stronger. Even a small order by an existing A380 operator will be one of a limited number of possible engine sales, so the outsider will fight extra hard to unseat the incumbent supplier. That the engines are also unlikely to find use on other aircraft only reinforces this. Boeing’s proposed 747-Adv, for instance, will use scaled up versions of 787/A350 engines rather than smaller versions of A380 engines. As such, despite the $12-15 million pricetag on each engine, the manufacturers will only have a small number of chances to recoup their development costs.||**||

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