In conversation with Rolls-Royce CTO Paul Stein

It’s not something you expect: the Chief Technology Officer of Rolls-Royce, Paul Stein, sitting quietly among kids in the UK pavilion at Dubai Expo. But there he was, attending the Rolls-Royce Science, Technology, Education & Maths session to inspire children for technology. And hopefully, become a CTO somewhere. In conversation with Rolls-Royce CTO Paul Stein. While Stein is moving on next March to take become chairman of the Rolls-Royce Small Modular Reactor (SMR) program and is succeeded by Grazia Vittadini, he was most willing to discuss the various programs and the engine maker’s future strategy. Paul Stein is very proud of the electric ACCEL aircraft that on November 16 became the world’s fastest electric aircraft, flying at 559.5 km/h and the fastest climb to three kilometers in 202 seconds “It’s the fastest electrically-propelled machine that mankind has made. So we're quite proud of that. And ACCEL really along with what we're doing next door is part of us giving back to the community because we recognize we need to inspire the next generation of young engineers and scientists and hopefully, the Raspberry Pie kits that the kids are playing with next door and the ACCEL aircraft and all the videos we're showing or the various products will create at least a few engineers in the future.” AirInsight: But how much of ACCEL is going into the next generation of airliners? Stein: “ACCEL has been a way of us testing out the battery systems, the parallel products, the motors, you know, in a real high-stress environment, massive discharge on those batteries to achieve that power output to punch through the airspeed record. The data that we've been collecting on the battery performance battery charging regime and all that sort of stuff is now invaluable data that makes its way forwards into sort of passenger carrying or unmanned services.” The ACCELL broke the record for the world's fastest electric aircraft on November 16, hitting 559.5 km/h. (Rolls-Royce) “I think we've made public our relationship with Vertical Aerospace, where we're the propulsion provider so all that technology is now being put to use this motor as the first application for an eVTOL vehicle. But Vertical is not our only customer. We're in discussions with a number of different providers but Vertical has been a sort of lead customer. They're a great company and they have a pretty good pathway towards certifying pure electric eVTOL aircraft within about four or five years.” AirInsight: I remember seeing a Rolls-Royce presentation at the 2019 Dubai Airshow, in which your company laid out the roadmap for electric, hybrid-electric, and sustainable aviation fuels. Is that roadmap still valid? Stein: “Yes, we are completely committed to that. We've stuck to it ever since then.” AirInsight: Of course, since then hydrogen has moved in. How has this changed your view on the way to go in the future? Stein: “Well, there's a remarkable similarity between the roadmap that we spoke about in 2019. And the roadmap required of hydrogen, you know, there's two ways in which you can use hydrogen. You can burn it in an engine or you can convert it to electricity where the fuel cell and propel the aircraft that way. We're running experiments right now and Loughborough University in the UK, on flame stability and all the other things that you need to establish to create hydrogen aircraft. Then it will be up to Airbus to do the rest of the system, how they manage the fuel, and the airplane safety and certification pathway. So with what we're doing with our research into direct burn, hydrogen is entirely compatible with what Airbus is doing. And then if you want to use it in a fuel cell, well then electric propulsion is the powertrain so that's fully compatible as well.” AirInsight: How much is hydrogen in your plans for UltraFan, your next big engine research program? Stein: “Right now, hydrogen isn't on the UltraFan roadmap. Because it's all experimental. Everything we're doing in hydrogen is experimental knowledge-gathering, positioning ourselves, in case our framers want to go down that route where propulsion providers, so we've just got to provide what the airframers want. We're going through the knowledge acquisition stage.” AirInsight: Has changed Airbus’ decision to commit itself to building a hydrogen-based airliner by 2035 changed your view of what should happen in the next fifteen years? Stein: “No, because we know that hydrogen is an option for the future of aviation propulsion. We have a very kind of straightforward analysis of the future of aviation propulsion. And if I can answer your question in a more systematic way than just simply chipping away at the hydrogen issue. We are absolutely convinced that for medium to long-haul flights, we will decarbonize aviation. We're 100 percent sure of this. By the evolution of our jet engines into UltraFan and actually, also our business jet engines and our long-range engines will run on sustainable fuels, which will be introduced through a blended increase of some kind. Probably as per the EU refuel mandate, which is a blend trajectory that goes through something like 10 percent by 2030 and 20 percent by 2035. And if we had 100 percent today, we would use it.” Paul Stein applauds Airbus' commitment to hydrogen but thinks it will take a lot of work until long-haul aircraft will fly on hydrogen. (Airbus) “Decarbonizing medium to long-haul, we’re absolutely crystal clear see the need for very, very efficient engines because we know the fuel will be more expensive. Some customers can run 100 percent SAF if they wish. We're going to certify our engines very early so they can run on 100 percent SAF and if customers can get hold of it, that's great. That's brilliant. But for the bulk of the industry, because of the enormity of the ramp-up required, we need 500 million tons, which is a massive amount of capital repurposed by the big oil and gas companies like Shell, Total, Air BP, and Exxon Mobil. We're very proud of Shell's commitment to two million tons by 2025. That's great…” AirInsight: That’s still small… Stein: “Well, it is a start. Every step through the forest has to have a first step. So they've led the way and the Americans as you know, moving heavily into SAFs through viewing how tax credit should be given to carriers and also just simply pump-priming money to create a SAF industry. So SAFs are happening, right. More efficient engines are happening. We talk about UltraFan as our big contribution to that in a bit. At the small end of the market, pure electric is here and now. You've seen ACCEL flying and you've seen the number of eVTOL companies that are set up all around the world. We are certain that many eVTOL applications will require a range extender or a turbo-electric generator, burning SAFs to extend the range of the battery. And that's why we publicized a relationship with the German government to create a turbo-electric generator in Brandenburg and that's going to be a world-beater on power to weight ratio.” “Now, between the two, there's some exciting space for innovation. So between the sort of, I don't know 1.000 kilometers and the perhaps 200 kilometers we're going to get from pure electric, there's some really exciting innovation to be had. As a propulsion provider, we're in a position where we can actually back most of the trajectories. So if there's a route to manage the engineering maturity challenges of hydrogen early, then we can follow that path. If sustainable fuels ramp up in volumes, and the need for hydrogen is less, we can follow that path. And if customers want hybrid-electric with a range extender, we can follow up. So I think we're in pretty good shape. Really, we've not excluded anything. But we backed heavily UltraFan, sustainable fuels, electric, and hydro-electric. And then we've kept options for everything else.” Despite not having an aircraft program to power yet, Stein is very positive about the future of the UltraFan demonstrator. (Rolls-Royce) AirInsight: Speaking about UltraFan, you're almost ready to do the first ground test early next year. But then, what will be the application of this engine? A couple of years ago, it looked like it would be the New Mid-market Aircraft (NMA) from Boeing. On which aircraft from Airbus or Boeing will UltraFan be? Stein: “What I think is going to happen is that we will demonstrate UltraFan. Every indication is it's going to be a game-changing product, in terms of its noise, its fuel burn, and all the characteristics, its compatibility with electrification path into the future. And it's a scalable architecture. We haven't designed it for a particular thrust class. Well, the demonstrator is 84.000 pounds of thrust, which we chose so we can compare it with an existing engine. But it's a scalable architecture, and that's a big thing because, in the past, we've designed special engines for every airplane. Now we've got one scalable architecture that goes from 25.000-30.000 pounds of thrust to pretty much as large as you like. In fact, so large, that drag starts to become a problem because the fan is so big. But certainly up to 110.000 pounds if ever such an engine was needed.” “What will then happen is that we'll have dialogues with the airframers, who will then see the engine and I'm almost certain there'll be then discussions that unfold with Airbus and Boeing. We're not in the business of predicting what they'll do. We're in the business of showing them what a great engine UltraFan is going to be and then it's up to them to make a decision about what their roadmap is.” AirInsight: But you have exclusivity of the Trent XWB on the Airbus A350 until I think 2030-2031. Stein: “We have secured that position, yes.” AirInsight: Is it an option that they will replace the XWB with something from the UltraFan program because it's more efficient? Or is that eating into your business case for the XWB that you might like to extend for as long as you can for the next 10 years? Stein: “First of all, we never try and hold back technology. With stainable aviation fuels ramping up in 2030, fuel efficiency will be in massive demand. If customers want UltraFan, they will end up getting UltraFan. We’re not in the business of making airframers decisions for them. Our business is making the world's best jet engine. We will show it to the airframers and then they will go through a period of consideration about how they can capitalize on that technology and offer their customers the world's most fuel-efficient airplanes.” AirInsight: At this year’s Dubai Airshow, your President of Civil Aerospace Chris Cholerton talked about the smaller, single-aisle market as well. That Rolls-Royce is waiting and ready to go into the market again. That's of course the result of the scalability of the engine again. Stein: “As I said to you, it's scalable and it has been designed to be shrunk down or boosted up. So a version of UltraFan could be made available for that market. But that's not to say, we'd make a decision to go into it. It just means technically, it can cover that thrust class. And I think as Chris said, it just positions us for a future. This is a business still recovering. It's very tempting to make predictions about what's going to happen nine years out. I was watching the news this morning. And for example, some of the predictions of the return of passenger numbers are looking more and more optimistic with time. Nobody thought that. Recently, we assumed the market would recover 2024-2025. We're now hearing airlines pulling that date forwards. Maybe there'll be more optimism in the industry." "We've tried to invest wisely during the dip so that we emerge from it able to provide whatever propulsion solutions are needed for the next stage. And there's something really important for us. Certainly going into COVID, we were a company that just made engines for the widebody fleet and in civil aviation for the last couple of business jets. That really was our market share with some historical stuff still flying but largely in terms of new products. We're going to emerge from it with a fantastic relationship with the oil and gas companies in sustainable fuels. We believe way ahead of our competitors. A roadmap to make all of our products that we sell today compatible with sustainable fuels. UltraFan, having been ground tested, is an entrance into a whole new market that we didn't have any products before, which is the whole electrification piece. And we are preparing all of that sort eVTOL space and the Small Modular Reactor program, which is our little nuclear power station. It is meant to generate the sustainable fuels we need for the rest of the fleet. So I think we're pretty pleased with the way we've reshaped the company during that period.” AirInsight: Yes, but I want to find out what the applications of these engines that you are developing now will be. Or of General Electric’s RISE, for instance. In 2035, Airbus wants something with hydrogen. Do they need an aircraft in between? Will they or Boeing do another new program that needs your engine or some else’s? Stein: “Well, so Airbus ZEROe program does not produce transatlantic airliners. The first will be about a small turboprop and there’s some larger, blended wing body but these are not transatlantic airplanes. So if Airbus wants to continue with the success of the A350, it's going to have to carry on making gas turbines powered increasingly by sustainable fuels, with those gas turbines evolving in efficiency and the airplane design also evolving.” AirInsight: So there will probably be a more efficient version of the A350 on the horizon… Stein: “I'm not gonna say anything about Airbus its products. You can interpret it how you like. Boeing is a company that has to reinvent itself. It's gone through some tough times. They're great customers of ours as well. We're very close to Boeing. We work with them on a number of defense programs as well as on the 787. Everybody wants to see Boeing succeed as well.” AirInsight: But you as Rolls-Royce aren’t sitting on your hands until 2035 until something of a hydrogen aircraft is there. There will be a need for the UltraFan technology or whatever? Stein: “Absolutely. And you hear GE and Pratt & Whitney say the same thing. When all the CTOs get together, you’ll find us all saying exactly the same thing. As I keep repeating, there's a lot of knowledge that's needed in the world of hydrogen to get us to a place where we can help produce that roadmap. It's great that Airbus has stuck its head above the parapet, as we say, and is moving ahead with some concepts in hydrogen. That's great and we stand ready and willing to work with them when they've got to a point where they're ready to demonstrate or are ready to produce airplanes." "But before 2050, we're not going to be crossing the Atlantic on a hydrogen-powered aircraft. Those transatlantic routes are the big workhorses of the wide-body fleet. They will be powered by very efficient engines running sustainable fuels until 2050. Beyond 2050 I haven't got any idea, I won't be around anyway. But some of the young people next door are being inspired and who knows what the direction might be.” Electric motors on the Vertical Aerospace eVTOL is another key market for Rolls-Royce. (Rolls-Royce) AirInsight: One last question, if I may. When GE’s John Slattery announced the RISE program this summer, he invited Rolls-Royce and Pratt & Whitney to join the competition and the race for technological innovation. What’s your response then to that invitation from GE? Stein: “We always say General Electric makes a brilliant competitor for us. They're a great company. We respect them and they've done a great job, so we don't look down on the competition at all. We have our own pathway on the sort of larger 25K to up to 120K engines. We’re very pleased with UltraFan, it's quite a breakthrough architecture combining incredible propulsive efficiency through having an ultra-high bypass ratio with great thermodynamic efficiency and with a completely redesigned core. Many people don't know that the core we use right up to the latest XWB is broadly the same as the RB211 that was invented in the 1970s. So it's time for something new. We haven't released the numbers but these are sort of significant steps above the efficiency of the existing core. Coupled with that big fan, which gives you another few percentage points efficiency by having a slow turning fan that is has got a huge bypass ratio with the core being a very small component of the fan. And then aircraft integration is thought about right from the start which gives you another few percent of efficiency. And then the whole thing's got an upgrade path. Now we're very proud of that roadmap and we'll leave GE and Safran to make their own claims about their technology.” AirInsight: So ground testing of UltraFan starts in 2022 but the first flight is not confirmed? Stein: “The program from then on is then going to be subject to the discussions with the airframes because we're not going to race ahead and do something ahead of the market need. We're not speculating when the first test flight will be. We've declared the ground test, we're going to take it to ground test, and then there will be discussions. When we show UltraFan working, believe me, journalists like you are going to be very interested in the results. We've got marvelous Testbed 80 which we're going to be using for demonstrating its capability. And then the phones will be ringing all the time between ourselves Airbus and Boeing to decide what happens next.” Paul Stein has been CTO at Rolls-Royce since May 2017, having joined the UK company in January 2010 as Chief Scientific Officer. He will work alongside Grazia Vittadini until the end of March when the former Airbus CTO takes over as the new Chief Technology Officer at Rolls-Royce. Stein will then chair the SMR program plus some other projects with the company as well.

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