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Four questions to Éric Schulz, President of Civil Large Engines at Rolls-Royce
10/13/2015
| Interview in Toulouse by Romain Guillot
© Le Journal de l'Aviation - all right reserved |
Le Journal de l’Aviation met Éric Schulz, the President of the British engine manufacturer Rolls-Royce's "Civil Large Engines" branch last week to talk about the range of Trent engines. Rolls-Royce is now the exclusive supplier for Airbus's A350 and its future A330neo, while maintaining its presence on the current A330 and A380, as well as on Boeing's 787 family.
The new Trent XWB-97 (with 97 000 pounds of thrust) will soon be starting its flight tests. What can you tell us about this campaign?
The first A350-1000 engine has just been delivered to Airbus to fly on the A380. Its first flight is expected soon, even if there may still be a few days' drift for one reason or another. As we did for the Trent XWB-84, we are going to "debug" the flight domain and understand how the engine behaves. We will then enter a phase where we will produce engines for the first three A350-1000 intended for testing. The advantage of the A380 flight bed is that we can collect information in flight as quickly as possible.
Rolls-Royce was hit by the slow-down in sales for the Trent 700 this summer. What's happening now?
It's slightly paradoxical and Airbus is pretty much in the same situation as us. On the one hand, we have a full order book for the Airbus A350 and the future is relatively secure, and on the other we have the bridge to cross between the A330ceo and the A330neo. I would say that today, with the latest order from China [The China Aviation Supplies Holding Company has signed a framework agreement to acquire up to 75 A330 with 45 definite, ed.], we are much better equipped to deal with this transition. We now have a very healthy order book.
What are the objectives for the Advance and UltraFan programmes?
The UltraFan is Rolls-Royce's vision for the very long term. Why? Because we are facing a physical problem in that engines keep getting bigger and the bypass ratio rate keeps rising. To be effective, the turbofan needs to run more and more slowly on the one hand, while the low pressure turbine, like any other turbine, is effective at high speed. The other phenomenon is that the slower a low pressure turbine runs, the larger it must be, which adds even more weight. While we can still reduce the weight significantly for the fan, it's more difficult for the hot parts. The only thing we can do is to put a gearbox in place in time.
But as we come from triple-spool engines, there's no justification yet for using a gearbox in relation to our bypass ratios. Unlike our competitors who use two-shaft architecture, our third shaft is only used to manage the fan. We can still brake the low pressure turbine to adapt it to the fan speed. The problem we are finding is one of turbine effectiveness, but at bypass rates higher than those of our competitors on the double bodies. This is why we are thinking about using the UltraFan at a later stage, in the second half of 2025.
As for the Advance, it will be a new generation engine which will start to prepare the way for the transition to the UltraFan because one of the physical obstacles that we will encounter is the redistribution of the work between the intermediate compressor (IP) and the HP compressor.
Do you think that the geared architecture will be adopted by most engine supplier?
I think that we are all facing the same dichotomy between fan speed and turbine efficiency. Pratt & Whitney has already chosen the gearbox solution but unfortunately physics is not linear. The issues encountered at 25.000 or 26.000 pounds of thrust are not the same as at 100.000 pounds. Four times the power means that you are confronted with oil cooling and shaft power problems, which are radically different. This means that the technological solutions will not be the same. This is why we are planning for the UltraFan after 2025.
The Advance's demonstrator should be running on test-bed in 2017 and we hope to see it enter service around 2022-2023. For the UltraFan, we are targeting 2028, even if there are numerous technical problems to be resolved before then. We are expecting fuel consumption savings of around 5% for the Advance and an extra 5% for the UltraFan, which means a saving of 10% in relation to the current Trent XWB.
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Éric Schulz
