Podcast: How NASA's New 2050 Goals Could Reshape Airliners

Sixteen years after the launch of its ground-breaking N+3 project, NASA is using the same model to once again accelerate the pace of advancements as aviation strives for net-zero carbon emissions by 2050. NASA's Rich Wahls joins the podcast to discuss AACES. 

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Transcript

Guy Norris:                   Hello, and welcome to Aviation Week's Check 6 Podcast. I'm Guy Norris, senior editor, and with me is Graham Warwick, executive editor for Technology. Just a few days ago in mid-November, NASA awarded a series of contracts to develop sustainable concepts for future airliners for the 2050s. Issued under the Advanced Aircraft Concepts for Environmental Sustainability, or AACES 2050 Project, Phase 1 contracts were issued to Boeing's company Aurora Flight Sciences startups Electra.aero and JetZero, engine maker Pratt & Whitney and the Georgia Institute of Technology.

                                   If this all sounds a bit familiar, it should do. AACES follows a tried and tested blueprint first drawn up by NASA in 2008 when it launched the N+3 Project to identify concepts in technologies for airliners that could enter service in 2035. This ultimately led to the agency's Sustainable Flight National Partnership, or SFNP, and the Transonic Truss-Braced Wing, (TTBW) X-66. So now AACES is looking to go beyond SFNP to see what comes next. To discuss AACES and an aggressive set of associated new performance metrics that NASA has just released, we're pleased to welcome Rich Wahls, SFNP manager, friend of this podcast and lead author of the original N+3 solicitation and who led the initial review recommendations. So Rich, welcome, and thank you for joining us. Can I start the ball rolling by asking, why is AACES shooting for a 2050 timeframe? Why not, say, 2040?

Rich Wahls:                   Well, first of all, thanks for having me on. I am a fan of the show. I learn a lot by listening in. So timing. Timing of AACES, it's, again, going back to look at what we did in 2008. We were trying to get beyond the horizon of what the next product cycle is to get people out of the box in industry and universities and also to allow, I think, for a reasonable timeframe for development to happen from something that's... really starts out at an exploratory level. So this is 2024. 2050 is only 26 years away. That's not that far really in the timescale of aviation.

Guy Norris:                   Right. And Graham, you were saying that, yeah, if you look back, indeed, that the original timescale from 2008 for N+3, pretty well follows the same pattern, right?

Graham Warwick:         Yeah, I think so. It takes a long time in this business to mature technology to the point where you can incorporate that technology into an aircraft development program and then obviously, then it takes time to develop the aircraft. So if you're looking at 2035, you really need to be able to make a product decision 2028, 2028, '29. Certainly by the end of the decade. Based on what we've seen the industry achieve in terms of development time felt, you've got to make that decision before the end of the decade, '28, '29. And then you work backwards from that to say how do we get technologies to the usually recognized technology readiness level of six, which is the proven at scale in a representative environment, which says we've reduced the risk to the point where we can put that into a product development program. Now it's actually getting more and more complex.

                                   It's not just TRL anymore. You've got to have all these other RLs like manufacturing readiness and integration readiness and all these other things, but they coalesce at a point where you say that technology is ready to buy its way into this product. So you work back from that and say, and if you're NASA, what you have to say is, "How do I lay out a road map that says, 'Here's where I, NASA invest government money with industry in technologies that I can get ready by that timeframe?'" So in the case of N+3 leading to X-66, you had to get started back in 2008 to get that technology road map laid out and then move up the readiness scale to reduce the risk. So if you now look at 2050, you have to start now.

                                   And we also know that N+3 left a lot of technology on the table because the studies that came out of N+3, which for you and I, Guy, were just like gold mines. These were just the most fantastic studies. We dug into those studies, we looked at the technologies, but a lot of those technologies were identified, but they were too far out. So you saw N+3 narrow down into what became SFNP and the technology specifically that are being looked at, SFNP, truss-braced wing, small-core engines, high-rate composites, et cetera. Now you restart that process and probably a lot of the technologies that were identified at the beginning of N+3 but left on the table because they were not ready will be looked at again and say, if we now look at 2050, do those technologies make sense?

Guy Norris:                   Yeah. And Rich, I know we briefly mentioned them in the intro there, but could you walk us through some of the projects that are now going to be included under this new phase or this AACES program?

Rich Wahls:                   Yeah, you went through them. There were awards and there's a Boeing-led team or Aurora with Boeing that's back in N+3, they were two separate companies and now they're one, and they have partners with them. Penn State, Michigan, MIT are involved with them. Electra, which interestingly is led by John Langford who used to be Aurora and now has a separate company, and he's got a team looking at distributed electric propulsion, like their smaller vehicle they're flying now. JetZero who's doing the blended wing body project now, they're going to be looking at a cryogenic hydrogen and they'll look at a tube and wing concept as well. Georgia Tech is the one university-led team. They've got a concept they're starting from that is hydrogen based, but they're, like other teams, are looking at the range of possibilities.

                                   And Pratt & Whitney is an engine-led company. They were involved with the MIT team in Phase 1 and others, and they're looking at starting with their HySIITE concept set that came out of the RPE work. But as I understand it, they're looking at other concepts as well. I've, in this AACES process, been more of a consultant leading into it and haven't been directly involved in the selection process. So there's details I don't know, and I'm looking forward to seeing as well. But the basic premise was put yourself out there in the future far enough out in the future to, again, get out of the box. And in this case, it's like open the aperture to what you think the future energy state might be.

                                   Will we have a lot of SAF? Will it be hydrogen? Could it be natural gas based, whatever it might be, or highly more highly electric? And so there should be exploration just like there was at the beginning of N+3. What a lot of people don't remember is in that Phase 1, a number of the teams were looking at alternative fuels, not SAF, and it was pretty exciting. But then when they boiled it down to the end of Phase 1, a lot of those things got eliminated because lo and behold, 20 years was pretty short time to think they were going to change the energy infrastructure. So this opened the aperture again.

Graham Warwick:         So we wrote about, 'cause N+3 wasn't just the one study. Out of N+3 came, some of the projects had additional phases. So Aurora took over on leading the D-8 from MIT. They took it through several phases before they were acquired by Boeing. But Boeing, with what became the X-63, which their project was called SUGAR, and, of course, that went through I think five or six phases. It's still going in some ways on the exploring the fundamentals of the truss-braced wing, but out of that came X-66. And, of course, Guy and I love all the acronyms that come out of this. And, of course, and in that SUGAR study they had all these designs. They had SUGAR Volt, which was the hybrid electric one.

                                   They had SUGAR Freeze, which was the liquid natural gas one. So they did do this initial study of alternative energy sources, but I think it's much more core to AACES that it's not making the assumption that the energy stays the same going to 2050. Guy is very close following hydrogen for commercial aircraft, and he's noticed that this is really the first signs of NASA opening its aperture to hydrogen. Up until now, whenever we've asked the question of NASA about hydrogen, it's been, "That's the Department of Energy's job." But now we're seeing these studies at least say hydrogen's in the mix.

Rich Wahls:                   Yeah, so AACES is definitely a concerted effort that opens the aperture and looks at all these things. But through our University leadership projects, for a good four or five years now, we've had the CHEETA concept out of Illinois that was a hydrogen-fueled cell-based concept, and there've been other lower-level activities. Starting around 2020 is when in Europe hydrogen became the popular thing, and we've had some exploratory studies. We weren't going to immediately change the direction of the ship and say that's the answer 'cause it's still not clear that that's the answer truthfully, and 'cause there's a lot of questions about how you transition to something different. Is there something that's more amenable to a transition to a different fuel? I don't really know, but that's why we're exploring it. But AACES is a big push, and I think you'll see us talking about it in the future.

                                   You'll hear us talking about this transformative, what's the energy future landscape? And you'll hear AACES concepts. You'll hear a couple of the internal ones. I think Guy reported on one of the seedling studies we had internally at ISABI, the charge project, that's a low-level activity. And you'll hear CHEETA and there's other university studies looking at ammonia and things like that under John Cavolowsky's program. What some people don't remember, going back to N+3 again, is when we closed out Phase 1, there was a reaction. The NASA people were all excited about all the things and then there was, I don't know, "We're limiting a lot of the possibilities. Can't we look at an N+4 right away??

                                   And so when we did N+3 Phase 2, we allowed each of the four Phase 1 winners, awardees to bid on an N+4, a 12-month N+4, where we said, "What if we gave you 15 more years, 10 or 15 more years, what else would come back in?" I recall the only one of the four that bid on that was the Boeing SUGAR team. Everybody else said, "We want to keep focusing on our N+3 and dive into that." And that's what led to the SUGAR Freeze that was a LNG-based, high truss-braced wing with a tail cone thruster, and there's a report out on that in 2012. So the SUGAR Volt was the one that Boeing had GE on their team. And if you look back to 2008, there was talk about a lot of electrification. Airliners were becoming more electric, but not in the propulsion system. But in the eVTOL personal air vehicle, there was a lot of talk.

                                   And NASA had a concept called the N-3X that was a superconducting blended-wing body, so it was out there. But once we had the SUGAR Volt that had a NASA stamp with the GE and Boeing stamp that this is something that could be possible, that in my mind was a turning point when the whole electrified propulsion for large aircraft just took off. I remember Marty Bradley and I went to a battery conference and we were the only people... We did it intentionally. It was a pure battery conference. We were the only aviation people there. And then Marty got up and presented the SUGAR Volt, and our idea was, "Are these battery people going to laugh us out of the room?" And they didn't. They said, "It's a lot of work, but what you're talking about is in the realm of the possible," and a lot of work came from that all over the world, I think.

Graham Warwick:         I actually wanted to bring Guy in here so he doesn't just moderate. Guy's talked about the new metrics. He mentioned those early on. One of the things that we need to make clear is that NASA came up... and the industry loves this. Actually, I did an interview with John Langford at Electra, and he said, "We love those metrics." NASA came up with this generational idea of N+N, N+1, N+2, N+3, which was N was then the state of the art, and then N+1 was the next generation. So back in that mid-2000s, N was the 737-800 N+1, which what would become MAX A320neo type of technology.

                                   N+2 was the next generation on from that, and N+3 was that 2035 generation. Guy can address this. Looking back, that had a huge impact because you've got JetZero on AACES and JetZero is a blended-wing body. And a lot of the technology in that came out of a NASA program called ERA, Environmentally Responsible Aircraft, which was targeting N+2. So we have to realize that these programs, even though they've got these very simple names, N+1, N+2, have incredible lasting impact if they work right, and that's what AACES promises. But Guy, did you want to come in on that side of the thing?

Guy Norris:                   Yeah, I think one of the areas I did want to ask Rich about was these new metrics that we've alluded to a couple of times. The fact that they are this in black and white terms, something which everybody can aim at, and at least it's a nice baseline for everybody to judge their progress against if you like. What you said earlier, Rich, about you went to opening the aperture, you talked to the battery people all those years ago about the art of the possible. Now we're looking at now other energy sources. You've mentioned LNG, and of course, liquid hydrogen for the future. And it is become very clear that these new metrics have evolved to embrace that. And the fact that there's so much uncertainty still out there about what on earth we could end up in say 20 years or more with. So would you be able to just talk us through the revised targets a little bit and how that is reflected in that?

Rich Wahls:                   So the metric table has its origins way back in 2006, '07 when Fay Collier was the Subsonic fixed wing project manager. He and I think maybe Dennis Huff originated the N+1, N+2. And so we started with just N+1 and 2, and added an N+3 when we came out with this original solicitation. And the metrics changed over the years. In fact, when we put out N+3, we had a much more aggressive noise goal that was meant to be 55, basically no noise at the airport boundary. And the intent was through the Phase 1 and the Phase 2 work, we would revise them. We'd put them out as aspirational goals and see what we got back. Same thing, I think, can happen here in AACES, is that the far term goal, we put them out there.

                                   I've heard people praise them. I've heard people go, "Oh, my God, they're pretty aggressive in the timeframe. They're not that far beyond the midterm goals, but hopefully they find the right balance." Now what you alluded to with opening the aperture is in a world where you have jet A or drop in in carbon and fuel burn are pretty directly related, you could keep going the way we were going. But if you enter to a world where you have no carbon in the fuel and you make a choice to, for example, using hydrogen, you will have less carbon out of the tailpipe. You really need to look at carbon through the life cycle to be fair about it, but you also look at energy efficiency.

                                   And when I was doing IKO studies with the LTAG and we were trying to pull together a lot of hydrogen studies, the energy efficiencies were all over the map. And most of them had an energy efficiency hit if you went to hydrogen 'cause you're adding more volume and so more structure and more weight, even though the fuel's lighter. It felt like a pretty aggressive goal would be that if you could maintain energy efficiency and use hydrogen, then you were a winner. And so in the new table, there's a tougher goal with more fuel burn reduction if you're using a drop in fuel versus maintaining the same kind of midterm level goal if you're using something that's zero carbon just to scope the landscape out.

Guy Norris:                   Right. And we've seen how you've gone from fuel burn, as you said, to basically like a broader vehicle level energy consumption metric, then therefore that's based on that kind of combination of looking at range and aircraft geometry and all those factors. But one of the other ones that I thought was interesting was the move to the nvPM, the non-volatile particulate matter aspect. And the way that this probably reflects the growing awareness of contrail emissions and the propulsion system being designed to, at least with that in mind.

Rich Wahls:                   Yeah, it's that. It's also one of the local air quality factors. And it's also, there've been changes in the CAPE standards in the nvPM area in the last three or four years, and so it's acknowledgement of that. If you look back to the original N+3, there was a row for field length 'cause everybody was talking about short takeoff and landing. And so we've morphed over the years. We also used to have a cruise NOx metric, and since there isn't technically a cruise NOx metric in CAPE now, we took that out. But the nvPM is in there and for the reasons you say, I think tied to contrails, tied into local air quality, it's relevant to put it in there.

                                   And you always keep noise in there, and the noise isn't going away and fuel burn, but a big difference on the fuel burn to energy consumption thing. So personally, I think when anybody talks about fuel burn, they really ought to be talking about energy consumption. When you start mixing batteries in hybrids, it really is what's the energy you're using, and you really do have to track the life cycle to see where that energy's coming from to know whether you've really made progress. But the big difference is rather than tying energy consumption to a best in class or a specific airplane, with the CAPE CO2 standard that's weight based, we now have a specific airplane agnostic metric that you work against this line. But it's an energy efficiency. It's an energy metric. It doesn't take into account the cleanliness of the fuel per se, so it's still challenging.

Guy Norris:                   Yeah. Graham, any last thoughts from you before we wrap?

Graham Warwick:         I really just want to emphasize the importance of what came to be the importance of N+3. It started as a series of very interesting studies, but it has proved over time that it mapped NASA's roadmap for the years that followed. We have a new generation of engines in development with hybridization designed in from the beginning, small core, very high bypass ratios. We have the ability to go to very high rate composite airframes very quickly, which we need to do to renew the fleet quickly and get more sustainable aircraft out quickly. We've got to build, we've got to get to that 60 or 70-a-month rate quickly. We can't take years to get to 60 or 70, we've got to get there quickly. So we've got to tackle this problem about composites being very, very hard to make at a high rate.

                                   And then you've got the electrification, the hybrid electrified flight demonstration part of it, and not to forget, there's a bunch of stuff on the air traffic management side that's being done. And then the X-66, which we have no idea really what the impact of the X-66 is, but it puts on the table a possibility that Boeing may make an architecture change for a future airplane. And so we have to look at AACES in that context and say that if it works the way that N+3 did, then there will be a roadmap that comes out of that that will guide drive, whatever the term you want to use, NASA's investment and industry's investment because NASA Aero doesn't do anything on its own. It does it with an industry partnership, cost sharing and everything. So it will lay out this map, it will map out for the U.S. industry what this future pathway is. So we really need to understand now the potential importance of these studies to set that path for 2050.

Guy Norris:                   Well, thanks, Graham, and thanks to you, Rich, and also to NASA for keeping us gainfully employed and excited and for inspiring hopefully the industry in the next generation. 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. So bye for now, and thank you for listening.

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