FLUG REVUE February 2005: A380 engine battle

February 2005

TRENT 900 AND GP7200 COMPETE FOR A380 BUSINESS

By Patrick Hoeveler

The biggest and most powerful engine to have ever flown on an Airbus is about to commence its next set of tests. Soon the Trent 900 from Rolls-Royce, designed as a three-shaft engine, will be lifting off on the A380 megaliner after tests on an A340. Like the American rival model, the GP7200 from the Engine Alliance of GE and Pratt & Whitney, this engine had to undergo dramatic change, albeit in its case relatively early on in development, when the A380 customers requested that it should comply with the special QC2 noise limits at London's Heathrow airport. As a result, the designers had to increase the fan diameter to 2.95m. “Noise proved to be a very important factor at that time,” recalls Robert Nuttall, Vice President Marketing at Rolls-Royce, “but it was not the only design factor. We tried to find the best mix of thrust requirement, reduced fuel consumption, low emissions and low costs.”

The results of the flight test campaign appear to have vindicated the engineers. “The very good performance figures confirm the values obtained on the test rig,” Nuttall confirms. “Quieter, cleaner, earlier” is how he sums up the advantages of this engine over the competition. Moreover, thanks to the proven Trent family of engines concept, the risk is low, he points out. The new and most challenging features of the A380 powerplant compared with previous models are the fan with its swept blades, which amongst other things is responsible for the low noise emissions, and the principle of “counter-rotation”. Here, efficiency is improved by having the high-pressure system rotate in the opposite direction to the other shaft. “Both technologies have fulfilled our expectations,” says Nuttall.

Despite this, the engine specialists still had to make some relatively minor modifications to the turbine blades, the high pressure compressor and one gasket. The company is not expecting any major problems during flight testing on the A380, as computer-aided predictions have made it possible to examine operating characteristics to an ever greater depth. The first Trent 900s out of a total of 18 required for the A380 test programme are already in Toulouse. Meanwhile ground testing is continuing in Derby, England, so as to accumulate more experience with the engine.

Meanwhile things are also coming together for the Engine Alliance's GP7200. The otherwise bitter rivals, GE and Pratt & Whitney, formed a joint venture company in 1996 to tackle together the project of developing a powerplant for a new version of the Boeing 747 and the planned A3XX. On 3 December 2004, the GP7200 flew on the Jumbo Jet in Victorville, California, albeit on a flying GE testbed, as the 747 version was not implemented.

There are currently five engines running in the USA. Altogether Bruce Hughes, President of Engine Alliance, is planning to use nine units in the test programme. This is one more than the original number, and is required in order to complete the desired 8,000 operating cycles in time for certification in the third quarter of 2005. Changes such as modifications to the compressor and turbine blades had resulted in two months' slippage. “We are introducing the new hardware slowly. The changes are not enormous,” he says.

This summer the first engines will be transported to Toulouse for flight testing on the A380. As far as Hughes is concerned, the advantages of his product include reduced maintenance costs due to fewer parts in the two-shaft architecture of the GP7200. “We have a small performance advantage and should have the edge in the life cycle costs.” On the other hand, the Engine Alliance cannot currently guarantee compliance with QC2 for the A380 freighter. “We need more data,” says Hughes. Apparently they have some ideas for further noise reduction up their sleeves.

The Americans have pursued a strategy similar to that of Rolls-Royce over the design of the GP7200. “We took tried and tested components (from the PW4000 and GE90) and introduced new technology in a way that makes sense to the customer.” For Hughes, the new challenges lay in the area of the swept fan blades made of titanium, which had to be optimal from an aerodynamic and weight point of view, and the low-emission combustor. “In both areas we are getting good results,” is his conclusion.

The customers, who are being fought over “just as fiercely as on other programmes”, will soon be able to satisfy themselves of this. Following the latest order for the Trent 900 from Malaysian, the British have cut Engine Alliance's lead in numbers of firm orders. If one includes options, then both sides have about 50 percent of the A380 market, with Rolls-Royce having the most customers and Engine Alliance the larger individual orders. The majority of decisions for the remaining engine orders are expected by Hughes and Nuttall this year. As the Englishman points out, “2005 will be an interesting year!”

From FLUG REVUE 2/2005

Last updated 10 January 2005

FLUG REVUE, Ubierstr. 83, 53173 Bonn, Germany