Listen in to hear Frank Haselbach, president of ISABE and head of propulsion at Airbus, in conversation with Aviation Week's Guy Norris. They discuss various technology pathways for commercial engines to help decarbonize the air transport industry.
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Transcript
Guy Norris: Hello, and welcome to this edition of Aviation Week's Check 6 Podcast. I'm Guy Norris, Senior Editor, and last week, I was at the 26th International Society for Air-Breathing Engines or ISABE Conference in Toulouse, France. Now, we all know everything needs an engine, but as aviation faces the challenges of sustainability, radical alterations in cycle, fuels, and hybridization, where is the industry going? I sat down with Frank Haselbach, who is the president of ISABE and also the head of propulsion at Airbus, to talk over some of the difficult choices lying ahead, here's what he had to say.
Frank Haselbach: In this generation to come, and I think the next 10, 15 years will be full of an opening and diverging space of what is the best propulsion architecture for the next generation of aircraft, is it the evolution of the ducted turbofan, what we call the ultra-high bypass ratio turbofan going from the numbers of what, 9, 10, 11 today to 14, 15, that territory? Or is it, well, going open architecture, losing the casing, losing the nacelle, losing the fan casing, I meant, and having either the single-stage fan rise as championed by CFM, so GE and Safran, or something like an open rotor concept where you have two counter-rotating open rotors, going back to stuff which we looked at in the '80s and about 15 years ago with the counter-rotating open rotors of investigations. That is a key question of the industry now. We don't have the answer. There are pros and cons for both.
If I look at engines today to go to the theoretical limits of what you could do on propulsive efficiency or on cycle efficiency before you hit things like stoichiometric temperatures and other things or meaningful CO₂ limits, there's maybe another 30% of improvement there in that territory, and then in the integration is maybe a bit more. So that's what we are going at together, so that's an interesting time.
Guy Norris: Right, and of course we can't ignore the subject of what fuel will be powering all of these engines in the future.
Frank Haselbach: Yeah, absolutely.
Guy Norris: And I think that's another intriguing aspect here. Obviously, sustainable aviation fuels, it's not just about the problem of how to produce more, which we're hearing a lot about these days, but it's also about what sort of SAFs we're going to have, whether they're drop-in or even non-drop-in. There's so many debates aren't there, and so many areas where we just don't know the answers yet.
Frank Haselbach: Yeah. But I think the problem is very clear to everybody. We have to cut through the fossil fuel chain, so we have kindly, of course, an open chain, so we are taking energy which was stored 260 million years ago by not our ancestors, even earlier than that. And that of course was stored as we know over a long period of time, so it's solar energy which was stored then, and it manifested itself in terms of crude oil, gas, and coal. And using it today means that CO2, which was stored at that time, now gets out now and actually changes the propensity of the Earth's atmosphere to maintain heat, and as a result we have the global warming, so that's what we are fighting.
So cutting through this and saying, "Okay, I'm taking today's solar energy in terms of solar, wind, tidal, whatever, it's all linked to it, and turn it into renewable energies, which I can use, and either in form of biofeed stocks, waste, and so on, or in form of power to liquid, so hydrogen and carbon source, and then the Fischer-Tropsch mechanism to get to synthetic fuel. All of those things are possible." They, of course, have all to be scaled up to the needs of 500 million tons of jet A-1 type of fuel by 2050, and of course, it has boundaries and challenges.
And we had actually on this conference a very nice talk also from the Aviation Accelerator Initiative, which was looking at the overall ecosystem which can produce this stuff, and where are the boundaries, and what is the impact of neighboring industries, whether it's shipping or industry, industrial power, and fundamentally providing energy to society, so we can't do this in isolation.
So then, you go a step further. You mentioned drop-in and non-drop-in fuels, so clearly the big difference is... Drop-in means I do all of this and make sure that what I have produced still meets the Jet A-1 spec of fossil fuel. That's reasonably safe you could argue. It will be not a big change to aircraft or engine, and we have to investigate a bit, like blending. Does blending face a risk or so? But that's fairly simple for airports, fuel providers, aircraft manufacturers, engine manufacturers, airlines. Great.
Non-drop-in offers new opportunities. You can actually take certain things out like aromatics, so long molecules, circular chains of carbon hybrids, which have the propensity of forming soot and could be a core of contrails. And consequently, if you take them out, you make the fuels better for the environment because you have some non-CO2 effects, which are effective and better because you have less contrails or no contrails. But they then face the risk of, well, what do I do, for instance, in a big airport? Normally, the fuel comes in pipelines underneath the apron to the aircraft on the ground, so you have to be clear that you have to have then two pipelines for the old fuel and the new fuel because you can't mix them, so all of those challenges come in, and that's stuff which needs to be discussed and not only here around propulsion, but also in the wider sense of ACARS and the airport associations, and so on.
Guy Norris: Right. Of course, you do really get the feeling that at a conference like this, you're getting the nearest thing to a glimpse into the future, and at least a potential pathways to the future as well.
Frank Haselbach: Absolutely.
Guy Norris: At hydrogen, that's another huge area of debate here. I thought it was interesting, and I'm not sure if you were able to see it when NASA, where we are sitting here now actually in this room, presented a hydrogen-powered concept, which to me shows the promise potentially that the US is beginning to look perhaps more seriously as the first inklings of that.
Frank Haselbach: Well, that's good to see. Good to see. In my other role as from Airbus, we clearly are pushing hydrogen as an aviation fuel. And I haven't seen that particular presentation, but I know clearly that, for instance, hydrogen... Well, it has a very high specific energy per mass, a very poor one for per volume, and that's one of the challenges, that's why you have to go to cryogenic storage in order to get a better volume densities. But, of course, that then puts the challenges of managing that fuel, distributing it, preparing it for consumption in either a jet engine or a fuel cell to generate electric power, all of that you put into the aircraft and into effectively the industry who makes the vehicle. Well, in the SAF world, you put all the challenges and complexity into the fuel producers, so it's quite a difference in approach.
Nonetheless, we believe hydrogen is very good because you have no carbon, there is no CO₂, you can burn it, you will still have, if you burn it, still have nitrogen oxide and water vapor, and if you put it into a fuel cell, you will only have water coming out.
Guy Norris: And there's just two other areas I thought we could quickly touch on. One was obviously in your formal life at Rolls-Royce before you moved to Airbus, you were no doubt involved in the early days of some of this, but we heard about the hydrogen research that Rolls is doing, some of the more unusual aspects of it, and preparations for testing on the Pearl 15, which will be next year, which I thought was really interesting. I know others are looking at that too, but...
Frank Haselbach: I think all engine companies are looking at it because, clearly, we are quite a player in the industry and if we say we're going to go for hydrogen or listen to an extent, so now speaking as Airbus, so the Rolls guys have actually done quite interesting stuff. I think that in the beginning, did an investigation of getting a factory hydrogen burning on a (AE)2100 type of turboprop engine. That was just to get the whole system going, understand a bit the fuel system, and how you can do it. And now this, yes, they have the plan to burn on a Pearl 15, you're right on that one, and that will go to full power, so interesting to see how they prepare the fuel and so on. All with gaseous hydrogen still, I understand.
But, of course, all the engine companies are also looking at, well, how can we do pumping technologies for liquid hydrogen? Because you have to get to pressures above the combustion pressure, which means you have to have the ability to manage this. And then, this is, of course, rocket technology to an extent, but in rockets, on rocket engines, it's typically done for uses of once or five times or 10 times, not for 10,000 times, 15,000 times, so they're getting the cyclic life of such a component right is one of the key challenges, I think.
Guy Norris: Right, of course. And of course, this conference is quite well-timed for certain things. For example, Rob Miller came over from the University of Cambridge and used it as a platform to announce the work that they've been doing on basically trying to accelerate technology with the hope of saying if we want to stand any chance of meeting the 2050 emission goals that have been set for zero carbon, we really have to accelerate what we're doing now. And he's brought forward that his team, anyway, helped with really outlining a roadmap to try and bring that forward. And I think it was revealed in New York as well.
Frank Haselbach: Yes, it was revealed in New York. He actually published the report on Monday morning for the ISABE conference to have it on time for him to be able to talk about it, so we triggered that to an extent. We're quite proud about that. And it's an interesting one, and it looks to all the elements of... If you look at the net-zero plan of the industry, clearly it's, first of all, get more fuel-efficient aircraft out there. And clearly, that's in our own interest, and you know the challenges we have in the overall industry post-COVID to get the supply chain up and running again in its depths and in its, let's say, ability to deliver slickly to the end customer, to the airlines, but getting new aircraft out there which are replacing aircraft which are 20, 25% less fuel efficient is quite a significant contribution to net-zero. Otherwise, we would actually have growth at a much higher CO2 output, so that's the first leg.
The second leg is the stuff we're doing on the new propulsion systems and new wings, to an extent, in the aircraft world that engines and wings make aircraft better. The rest is very important, but not so important as those two things.
Guy Norris: It's all about the engines-
Frank Haselbach: Absolutely. Absolutely. So, that's the key. And this is where the discussion of UHBR against open fan and other things come in and best possible ways of implant planting it. And then, of course, it's the sustainable aviation fuels. And that is, for me, the drop-in, the non-drop-in, and the hydrogen to an extent, which then hydrogen drives another set of technologies again and will most likely not play a major role too, for the 2050 goal. But it will play a major role of preparing the second half of this century and then seeing... Because if you look at hydrogen, it's even a great fuel for long-range because you need less of it. It's such a powerful fuel.
Guy Norris: And of course, one of the aspects he did bring up was the idea of moon shots, these projects which...
Frank Haselbach: Wait, where hydrogen is one of them?
Guy Norris: Exactly. Hydrogen is one of them. And of course, talking of moon shots, guess we can't end this conversation without briefly, obviously mentioning you're also... We're here in Toulouse where Airbus is headquartered, you're Head of Propulsion.
Frank Haselbach: Yes.
Guy Norris: We are looking at now, the beginnings of a series of task programs, which are... I was trying to think about going back in the history of commercial aviation, it's really going back to the late '80s and early '90s when McDonnell Douglas put a UHB on the back of an early open rotary, basically on the back of an MD-80, tested two versions. It's like Back to the Future. Of course, that effort was probably ahead of its time. Ended because the oil prices went back down, and there was no need for it. But now here we are in the mid-2020s, where are you now in beginning to plan out this evaluation?
Frank Haselbach: So, we've been fairly public about this. We embarked on a project together with CFM, so GE and Safran because they came up with the rise concept, which was slightly different than the open rotors of the past, it's a bit simpler because it is only a single-stage rotating stage, so it's effectively a turbofan without the casing and the nacelle. But you have to have variable pitch and a stator in order to provide things like thrust reverse, and so on. So I looked at this when I joined from Rolls-Royce to Airbus, and said, "Well, that's an interesting idea," because it takes some of the complexities of the oil system, the mechanical systems in the older attempts away, which normally stands for, if you have complexity, you find technical solutions. But later on, you have massive amount of maintenance costs, and challenges, and so on, and I was fearing that you actually have a good fuel advantage, which you eat up by effectively additional maintenance.
So, this time, this looked a bit simpler, interesting in that respect, it's because of this slightly bigger than a counter-rotating open rotor, so you have to look at the integration, and that integration is the key challenge we have. So, of course, you have questions like, "Well, you lost your casing. You lost your nacelle. You lost your means of managing noise from the fan. How do you do that now?" So clearly, it'll be clever fan-blade design. On the one-hand side, you have a much lower pressure ratio, so that helps as well. And so you need to tackle now the noise at source, and that's what CFM is doing. So, they tackling the noise at source in order to get to levels, which then allow for the right margins to Chapter 14 in terms of community noise, in the right margins for effectively the working staff and the passengers in the cabin because our attempt is, if we do this, people should not hear the engine when they're sitting in the cabin, they might see something different outside, but they shouldn't hear it, so that's the target.
We are looking at, of course, you have no longer a casing which could hold a fan blade out. So you have to look at, well, how lightweight can I make this blade, and how can I actually shield the fuselage appropriately? And up to now, the preliminary work we're doing, all of that looks like it's within the margins and limits we set ourselves, so that's okay, you can account for that. And then, of course, you have to look at the parasitic losses you have on the L/D for the wing because you have a much bigger wetted area, which sees the turbulent wakes from the fan blades. So, all of those things are accounted for. We are working on them. We have a roadmap together with CFM to look at this. We have a technology program of engine tests and integrated engine tests, detailed tests, bird strike, and so on, in order to get the feeling, will that work.
And then, of course, we have in '27, '28 round about where we're doing the flight testing on an A380, which will give us, understand the means of compliance, get the altitude performance, doing all those things, and so on. All of that is technology. It's pure technology development. Understand whether that architecture could be the right architecture for the next generation of engines and aircraft. And also, of course, it's the question of saying, "If I do all of this, do I get it to the right weight? Do I understand the projection of the maintenance costs?" And so on, all of those things. So it is a great adventure, and really, it's a great time for a propulsion engineer in an aircraft company, I can tell you.
Guy Norris: Fantastic. Yeah, of course, as you mentioned, an exciting time for really anybody who's thinking about a future in propulsion or in engineering like that. Well, Frank, thanks so much for your time. It's been a pleasure, and hopefully, the next time, or sometime in the future, we'll be seeing results of these flight tests.
Frank Haselbach: Absolutely. I believe. I can't wait, I tell you. Thank you.
Guy Norris: Thank you. Well, that's a wrap for today's Check 6. Don't forget to follow us in your podcast app of choice, and one last request, if you're listening to us in Apple Podcasts and want to support this podcast, please leave us a star rating or write a review. Goodbye for now, and thanks for listening.
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