 Hi, welcome everyone. My name is Dana Weinstein. I'm Associate Dean for Graduate Education here in the College of Engineering at Purdue and it's my pleasure to open up this Purdue Engineering Distinguished Lecture Series talk. So the beginning in 2018, the Purdue Engineering Distinguished Lecture Series invites world-renowned faculty and professionals to Purdue Engineering to encourage thought-provoking ideas and conversations with faculty and students regarding grand challenges and opportunities in their fields. Besides presenting a lecture to a broad audience of our academic community, I see across multiple levels here today, they also engage in an interactive panel with Purdue faculty and students. To welcome our esteemed Distinguished Lecture today, I'd like to invite Dr. Bill Crossley to this stage. Professor Crossley is a professor and J. William Urig and Anastasia Vornas, head of Aeronautics and Astronautics here at Purdue. He's been a faculty member since 1995. He's also the director for the partnership to enhance general aviation safety, accessibility and sustainability or PEGASIS, the FAA's Center for Excellence for General Aviation. So please help me welcome Dr. Crossley to the stage. Thanks so much. Great, thank you Donna and again as she said, I am the J. William Urig and Anastasia Vornas, head of Aeronautics and Astronautics. I'm really pleased you're joining us for the pedals lecture today. So my job now is to introduce our speaker, Dr. R. John Hansman. I've known John for probably 20 years, although we were joking that maybe I started at Purdue when I was 12. So we're trying to figure that one out. John's got a great resume here. I'm going to try to do it quickly because he said cut it down short, but he's done so many neat things. He's the T. Wilson Professor of Aeronautics and Astronautics at MIT, where he's the director for the MIT International Center for Air Transportation. He conducts research and advanced technologies for operational aerospace and transportation. He has seven patents, has written over 300 technical publications. He's got over 6,500 hours as pilot and command in airplanes, helicopters and sail planes, including meteorological production and engineering flight test experience. So he's got some stick time in addition to his lecture time. Professor Hansman also chairs the U.S. Federal Aviation Administration Research Engineering and Development Advisory Committee. Most of us know that as the REEDAC, which is really important function supports the FAA. He's also the co-director for the National Center of Excellence in Aviation Sustainability, which is known as ASCENT. He's a member of the U.S. National Academy of Engineering. He's a fellow of AIAA. He's received numerous awards, including the NAAA Dryden Lectureship in Aeronautics, the FAA Wright Brothers Master Pilot Award, the ATCA, which is the Air Traffic Controllers Association, Kritski Air Traffic Award, a Laurel from Aviation Week in Space Technology and the FAA Excellence in Aviation Award. So I can think of nobody better to give us some insights about electric and more automated aircraft. So please welcome John Hansman. All right, thanks everybody. So I'm going to talk about electric and electrification automation, but I want to start off and use this as sort of a theme by how to think about innovation in general, but particularly in aeronautics. So there's sort of two ways to look at it. One is you're going to innovate because you have some new opportunity due to a technology push. There's new technology. There's something that you can do that you can't do. And this could be for transport airplanes or helicopters or general aviation airplanes. The other is you have a needs pull. So there's something that you need and you need to innovate to fix a problem. OK, so traditionally, a lot of our work early in my career was trying to work safety problems. OK, so anything you could do to improve safety, you would do. There was a lot of push on research and a lot of. So anytime there was an accident, you would be trying to understand the reason for the accident to that. Now, the good news is the air transportation system right now is incredibly safe. There is actually no other mode of transportation that's even close. Riding on an escalator is much more dangerous. Like we have an accident about commercial aviation, about 0.2 per million departures. So it's incredibly safe. Now that's a good thing. It actually makes it hard to innovate. OK, because I can't screw up the system. So if I do something new, I have to make sure I don't screw it up. And it's actually very hard to prove that you're not going to screw it up. So that's where sort of certification challenges come in. There are other needs pull in the one that's big right now is sustainability. So, you know, I'll get to talk about that more. But there are also things like what is the demand? Are there ways to scale the system? And again, are there new markets you can treat? So let me start by talking about the technology push in terms of electrification and automation. OK, so there's a lot happening in electric vehicles. If you see that picture in the lower right, there's all kinds of startup companies that are doing all kinds of weird vehicles. I'll talk about some of them. OK, there's also unmanned air vehicles that are showing up. And this is really driven by first electric electrification, you know, because of what we're seeing in the car market because of the advances in batteries. There's interest in electric vehicles, particularly because they potentially have lower emission and they enable something I'll call distributed electric propulsion. I'll get into that. We also have lightweight and powerful control systems. The sensors and the processors and the algorithms. You know, if I look at my phone, OK, I have much more processing power in the phone than the Apollo capsule had or anything even close. OK, and not only is it the processing, but it's the cameras, it's the sensors, it's the GPS and whatever. So this stuff is really small, really light, it really changes things. There's also advanced geometries that are enabled by materials, composite materials, ways to do very precise CNC molds, 3D printing, things like that. And finally, a lot of things that some people both here and we're doing at MIT are using sort of integrated design techniques that allow you to design the vehicles to be really the overall vehicle to be really integrated. OK, so let me start with this. OK, if you think about the quadrotors, OK, how many people here have flown a quadrotor? OK, many people, right? It's a commercial product. OK, that's an existence proof of what you could do. OK, and these things are actually amazing. OK, they'll fly pretty long. They're incredibly precise, stable. You think about the pictures we use from these things. You know, 30 years ago, this would be, you know, unthinkable in terms of this technology. OK, so so people were doing this. We had a lot going on and on UAVs and people said, well, well, let's just scale it up. OK, right? I just put a person on the thing. OK, now, by the way, remember, I'm sorry, the safety thing here, the quadrotor has quadrotor. What happens when one rotor goes out in a quadrotor? You lose the vehicle, you crash. OK, so we can't do that. So even on this, and this was the early Volocopter, OK, you just scaled it up. It's basically a quadrotor. It has more than four rotors, so it's a multi-rotor. You can say it's got a sophisticated landing gear system and things like that. But this was actually the prototype of what became a company, OK, in Volocopter. This is one of the vehicles that people are pushing in terms of this distributed electric propulsion. So it's just a scale up of the multi-rotor. And by the way, Volocopter is not the only one. There's a Kitty Hawk flyer. I don't know if anybody's ever seen a picture of this. Same idea. This was actually funded by Paul Allen, OK, from Google. It's sort of a startup with Sebastian Thrun out of Stanford. And, you know, if you look at it, it's interesting. Now, the lower left picture was the initial prototype, OK, pretty sketchy. It kind of fails that safety case, right? By the way, you're given an exemption on the safety side if you're an experimental aircraft or if you're very small, less than 254 pounds empty. So these guys sort of were flying under that kind of safety exemption case. It was very sketchy. You'll notice some pictures of these. They're never over anywhere except water, OK, right? And then the picture in the center is a more modern version. So this was going to be a product. They sort of decided it was too sketchy. It's not going to happen. The Chinese got in here. So they're Ehang. Same idea, which is you have a multi-rotor system. These are being flown with two passengers in the vehicle. So they're there. I'll get back to it. One of the problems with the multi-rotor systems that are particularly the battery only one is they don't fly very long, OK? So there's problems with the battery technology. So you can't get a lot of endurance for them, but they're sort of good for very short missions. But that stimulated and there's been a huge expansion of different vehicle architectures. This is a way we decompose it. You can think of it in terms of systems that have a few propulsors and others that have many propulsors or motors. And then there's rotor lift. There's actuating hybrid lift, which is basically tilt rotors. There's static hybrid lift where you basically have a lift plus cruise. So you have wings, OK? But you sort of take off vertically. I'll show you some more. And then there's conventional take off and land and I'll get into some examples of that. So let me start with a lift plus cruise. This was also started very early. Back, again, Paul Allen, who actually was sort of the center of some of this initial starting. So the Silking Valley money sort of went into starting this business. He funded Alain Crow from Stanford, the stealth company, which is called Z-Aero. And that's the patent out of Z-Aero. And that's the lift plus cruise. So the idea here is you have one set of motors that lift the airplane off the ground and then you have a pusher or some other propeller to get you going forward till you get on the wing. And then you sort of fly on the wing. Z-Aero actually went into Kitty Hawk, so they were, Paul merged Kitty Hawk into the Cora, which is in the lower left. And now Kitty Hawk has combined with Boeing into a company called WISC. So that's the WISC airplane there. It's a pretty sophisticated design. It's two passengers, I'll come back to it, and it's fully automated, OK? With two passengers, they didn't want to, you can't afford the weight of the pilot so you basically just stick with the two passengers. We'll get into those challenges. There are other versions of this. This is the beta airplane. Actually, let me go back to some features. On this, on the Boeing WISC, if you look at it, the motors are actually very clever. They're pancake motors that have low drag. When you start going forward, you don't want a lot of drag on the motors. So they're very sort of thin motors with a low drag. You also, you'll notice you actually have 12 rotors on this vehicle. OK, because you have to deal, you still have to be able to fly the vehicle when you have an engine out-condition. The beta Aaliyah is an interesting airplane. So this is showing here, this is a company in Vermont, similar idea, Lyft plus cruise. You can see a picture of it on the left. You can see a picture on the right in flight, forward flight. OK, if you look carefully, you'll notice there are no rotors on it. OK, so they're having trouble with the motors. OK, you'll notice they only have four motors. The way they get their redundancy is each motor actually has multiple internal coils on it. So even if you short out one motor, you still have propulsion on that side. So that's the way they sort of are trying to do the safety case there. Another variant of this, this is the distributed electric propulsion tilt lift, is the Joby vehicle. In the Joby vehicle, the propellers basically or the thrusters lift you. And then once you get in the air, they start to tilt forward as you accelerate. They tilt more and more forward. So you can see it on the left in the climbing condition. And on the right, you can see it in the forward flight transition. Let me say all of these vehicles are very difficult to fly during the transition. So transitioning from the static to the forward is tricky from a flight control standpoint. There's some other, I like this one. There's another cute one. This is one of the small, sketchy, high-risk ones called the opener Blackfly. So this has got eight motors. It literally will pop off the ground, okay? Like a can opener and sort of fly around. It's in the ultra-light category. So it's, again, a single person airplane. Then there's another variant of this is the Archer Midnight. This is a mix of the tilt rotors which you can see in the front and then just the lift motors, which are on the back, okay? So there are different variations here. And finally in this sort of category is the Lilium Quote Jet. It's really not a jet. It's just a bunch of small electric motors that are ducted. This is a German design. And interestingly, there's a lot of pictures of it in hover. I'm not sure they've flown in forward flight yet, so. But there's a picture of what it would look like in forward flight. And there's another approach to this. Actually, we were involved in it looking at the technical challenges and asked the question and got involved in something saying, well, what if you took the same technology instead of trying to lift up and do vertical takeoff and land, what if you try to take off and land in a really short distance? And so there's a company called Electro which is doing a blown lift hybrid electric. And basically we can, on a fairly large airplane, take off and land in about 100 feet. The way we do this is with blown lift technology. So the idea here is if you blow over the wing with a deflected flap, you get some lift from the deflection of the flap and you get a delay in the stall speed. So you can get very high lift coefficients. Lift coefficients like six or seven or eight, okay? Which allows you to fly incredibly slowly, okay? Now this idea has been around for a while. In the 70s, NASA in Europe, they did tests of airplanes with blown lift, but they were the mechanical propulsion systems which were very complicated. The distributed electric propulsion is a really elegant application of this because it's very easy for me to now put my motors along the leading edge of the wing. And this is much more like a conventional airplane. So we got involved in it in student design projects, did some initial feasibility studies, did a four passenger concept design. We then did wind tunnel testing of the blown lift capability and the students designed and built a 30% scale demonstrator. And this technology was then handed off to a startup company, Electro, which is building the airplane. So this is an Electro slide. You can see them pointing to the MIT tests and we're building right now a two passenger technology demonstrator. This is now not battery powered, it's hybrid electric. I'll get into that in a minute. But it's got four motors on each side. The test airplane is based on a Cessna 172 wing with a bespoke fuselage in the propulsion system. And then there's a product. This will be flying next summer or spring. And I'm sort of lined up to be the test pilot on the airplane. So I've been spending a lot of time making sure they don't screw it up, okay? So that's kind of the technology push. Let me now switch to the needs pull and go in a different direction. The biggest thing that's going on in the overall aerospace industry, if you talk to the people of Boeing or Airbus or whatever is concerned about sustainability, okay? This is an existential threat to air transportation. So there's huge focus on environmental impacts. Primarily climate change and carbon emission and global warming, although there's concern with other emittance. The first thing to note though is that basically emissions scale with fuel burns. So anything you do to improve fuel efficiency will improve the sustainability of the airplane, okay? So this increased focus on greenhouse gas emissions is really, as I said, an existential threat. Aviation today represents between two and three percent of the manmade or anthropogenic greenhouse gas emissions. However, as we move to other electrification in industry and in cars and whatever, the percentage attributed to aviation is gonna increase. So there is a real concern about flight shaming in basically the degradation of the market. So the industry is trying to figure out how to close the gap. Now one thing to note, remember I said that the emissions scale with fuel burn, okay? Where is the fuel consumed? So this is a plot from Brian Yuko who's the chief engineer for sustainability in one of my former students at Boeing. This actually comes from his thesis is this is a plot of the flights around the world, okay? The green is the number of departures as a function of stage length and the blue is the fuel consumption, okay? And what you see is that 50% of the departures are, let's say the right way to say it, because I think about this differently, but basically the story of this plot is that most of the fuel is burned on long haul propulsion, okay? So 50% of the fuel is consumed by flights greater than 2,800 kilometers, whereas 50% of the, where that's 90%, only, sorry, only 12% of the flights, okay? So the idea here is if you really wanna make a difference you wanna work on the long haul, that's by the way the hardest technically to solve. So this is the challenge for all of us. Okay, so there's many different approaches to this, to sustainability, this is where the electric comes back in, a battery electric, hybrid electric, hydrogen, and then there are things you can do in conventional. Battery electric sounds really good, okay? There's zero emissions, by the way, that's only if you get your energy from a clean grid. Most of our grids are not that clean, okay? But in the future we'll have cleaner grids. And as I told you in the beginning here, electric allows you to do all this distributed electric propulsion stuff. So there's all kinds of interesting things you can do. However, you're really limited on what you can do, particularly in the range payload, okay? We'll get to that. There's also safety and certification issues and a bunch of detailed issues. Let me get to the battery issue. Okay, so here's the problem. Batteries sound good, but they're not very energy dense. If you think about jet fuel, okay? It's got 11,000 or about 12,000 watt hours per kilogram of fuel, okay? If you think about batteries, the best batteries are about 400 watt hours per kilogram, okay? So you're paying a huge hit on weight, okay? And then by the way, you can't get the energy density from this, this is at the cell level. When you start actually looking at how you would use it, you get what we call knockdown factors, okay? So you need to take those cells and you need to pack them in something so if they catch fire, they don't catch the other cells on fire, okay? So you lose about 25% there, okay? You actually don't know how much energy you have in the cells, okay? Anybody ever had their computer run out of energy or do you know exactly how long it's gonna be before your computer runs out? You have no idea, right, okay? So you gotta deal with that, okay? Then as the computer gets older, it gets worse. And then by the way, for airplanes, you can't run out of energy in the air and you're distributed to electric propulsion airplane or you're in a brick, right? Okay, so you gotta be on the ground. So you've gotta have margin, okay, which we consider to be reserves. So really only about 25% of that energy is available for the mission. So it really limits what you can do, okay? So there are many people doing battery airplanes if you go look at the market. So what I've got here are some examples and by the way, this is my, this is Hansman's scorecard on the reality check is the color, okay? So if you go to that whisk airplane I told you about, that's a two passenger airplane. They're talking about missions of 25 miles. That's probably doable, okay? Joby, they've got a five passenger airplane at 150 miles, questionable, okay? Lilium, seven passengers at 155 miles, really questionable, okay? Region, I didn't talk about region. Region is interesting. This is actually using the battery technology but for a wing and ground effect seaplane that takes off on hydrofoils. They're talking 180 miles, 12 passengers, that's probably doable, that's green to yellow. And then there are people doing sort of retrofix into conventional airplanes, aviation and heart. If you look at their numbers, it's just hard to see how they're gonna work, okay? So they get the reds, okay? The other thing is I mentioned the battery thermal runway, almost everybody who's worked in this space has had a fire on their, this is the aviation prototype airplane that burned itself up, okay? So remember, you're not even allowed to carry your lithium ion batteries on the airplane, okay? So now I'm gonna carry them as the mission. Anyway, all right. Now an alternative is to go to hybrid electric, okay? And that has some advantages, so I still get all the electric configuration advantages but I can get better range and efficiency, okay? And in fact, one of the nice things about a hybrid is that I can run the turbine, run the engine in its ideal operating point. So instead of, right now we design the airplanes for takeoff, the engines for takeoff, and so at cruise there may not be at their optimal operating point. Here you can run at your ideal operating point most of the time, so you get some advantage. You can use some of the sustainable fuels, so it's okay. But it adds complexity and weight to the airplane, so it has to buy its way onto, what we call buy its way onto the airplane. There's some configuration, so Airbus is doing a fan demonstrator. Honda is looking at it for EVTOL. In that electric airplane I told you about is designed to be hybrid electric, again so that you could get the range and mission profile out of it. There's some other things you can do that people have been looked at for bigger airplanes. One of the things you can do on the right is the NASA, is the double bubble that came out of MIT and the lower left is the NASA Stark. It's something called boundary layer ingestion. So you get drag from the boundary layer that generates a terminal boundary layer on the fuselage. And the idea of boundary layer ingestion is if you suck that boundary layer into the engines and accelerate it with the engines as a thrust, you can get a significant reduction in the drag of the airplane, so that'll improve the efficiency. The problem in a typical engine is that the jet engines can't take the crappy flow that comes in from the turbulence. But with a hybrid electric, you might be able to get around that because the fans may not be as sensitive. The other problem, if you look at that double bubble case, there's a concern on what's called engine fratricide. But if both engines are next to each other and one of them blows up, it takes out the other engine, you lose the airplane. So there are some problems there. So there's some reasons why hybrid may allow some of these other capabilities to buy this way on. Let me also say a little bit about hydrogen. Hydrogen in some cases is part of an electrification, but also hydrogen and aircraft is effectively just a chemical battery. It's a way to take energy that you generate on the ground, put it in the airplane to use in the air. And there are different configurations. So you can use hydrogen as a direct fuel into engines. Jet engines will burn almost anything. You can do a hydrogen hybrid where you have a turbine that does the battery, or you can do a hydrogen electric fuel cell. So the hydrogen goes into a fuel cell to generate electricity for the system. Now the challenge in hydrogen is, how do you store it? The beauty of hydrogen is it's a chemical that has actually a higher energy density than jet fuel. The problem is its volumetric density is very poor. So it takes, or volumetric energy density is very poor. So it requires a lot of volume. You can basically compress the hydrogen down in a high-pressure gas storage, which I'm showing on the right. And that will work, but now you have the weight of that compression. So with new technologies, maybe we can get that down. There's some work there. Or you can compress it into a cryogenic liquid, which is what's done on spacecraft, or space launch vehicles. That's doable. It has a bunch of, however, operationally, it has all kinds of problems. And by the way, you now have hydrogen leaking around the system, which is not necessarily a good thing. So the pluses are it's zero emissions, if you can get it from a clean grid. It's got a potential for long-range flight, but there's all these other problems I just sort of talked about. It also, by the way, requires a hydrogen fueling infrastructure. So I have a hydrogen airplane. I have to only go to airports where I can refuel the airplane, which I have to think about. Okay, there are people doing it. There have been some demonstrations. Upper left is DLR, has a fuel cell case. There's a company called ZeroAvia that's retrofitting fuel cells into 19 passenger airplanes. And there's a company called Universal Hydrogen, led by Paul Aromenko, who was the CTO at Airbus for a while, which is doing compressed hydrogen retrofits. So there is action sort of going on in that space. And then there's some other cases here. Let me push over now to the automation focus, okay? A little bit, and say a few words about the automation. So part of the reason why we want to automate is by both the needs pull, is from the needs pull. We'd like to scale the systems, and particularly some of these things that you saw like the Evito airplanes, they're not enough pilots to fly those airplanes. So how do you allow the system to grow bigger, or allow more people access to aviation, okay? So there's a lot going on in autonomy, okay? Currently crew costs are a major factor for an airline. Crew costs are about 25% of the direct operating costs of a major airplane airline. So you'd like to cut those costs if possible. You also notice if anybody here has been on a flight that's been delayed, we don't have enough pilots right now in the US to fly all the flights that people wanna fly. So we really are at a place where we're being hung up by that, okay? There's been a lot, the lower left there is an Airbus cockpit, okay? And it turns out in most transport category airplanes, we already automate the flights, okay? On typical transport airplane, the pilots start the engines, they taxi out, they get at the end of the runway, they take off, they climb to 500 feet, and they turn on the autopilot, fly the entire flight on the autopilot, get to the final, and on flare and landing, they take the autopilot off and land. Their planes are technically capable of landing themselves at certain airports and runways. So we're actually very good, just like we were with the quad rotor, on automating what the lower right is showing kind of interloop control tasks, what that right picture is, is showing you the feedback loops. And what it shows you is that, from a flight control system, we're pretty good, we can automate that stuff. The harder stuff comes in, in where the humans are doing it, are really more at sensing the environment, understanding the situation, okay, which we call situation assessment, and then changing the plan if there are different conditions there. Now, there's a question as to whether that has to occur on the airplane or whether it can occur off. So there's a lot of work going on and sort of looking at how to do that. There's a project, this is kind of a joke, but there's a DARPA project called the Aircraft Labor and Cockpit Automation Sale alias that actually looked at that. And there are programs, some people call simplified vehicle operations. The idea here is to not get rid of the pilot, but to basically simplify flying the airplane so more people can fly more reliably. I'm a pilot, I actually fly it myself for transportation. I didn't fly out here, I should have, okay. But one of the challenges is in order to stay current to fly in all weather conditions, I have to spend a lot of money and fly a lot of different airplanes just to be current and with that. It's actually not that hard to do, but that's sort of the way the rules work. So we're trying to look at can the technologies make it easier to stay current or reduce what is required to be able to use the airplane as an operator. They're also there for some safety reasons, so this is actually the first certified full automation system on an airplane. It's called the Garmin Auto Land System. There are a couple of airplanes where if the pilot becomes incapacitated on a single pilot operation, a passenger can press a button that says emergency auto land and the airplane will actually fully fly itself, it will actually declares over the radio that it's an emergency, that it's landing and it will find an airport and it will land and it will get to the ground. And by the way, this is an interesting certification case because it was hard to prove, remember I told you you had to prove that you're not gonna degrade the safety in the system? It was hard to prove that this would work to the standards that would be accepted for very high level automation. However, the argument that the test pilots and Garmin made to the FAA is, hey, anybody who's pressing this button is gonna crash, right? I mean, the pilots incapacitated, right? So the downside was not that low. So they said, all right, we'll certify that one. Okay, all right. But that sort of motivated, there's a bunch of activity going on on this, okay? So I mentioned again, I keep coming back to it, the Boeing Whisk airplane, this is gonna be fully autonomous out of the gate. Okay, so they're never planning to have an pilot fly this airplane. If you leave and look at it, there's no control stick, there's nothing in there, you just fly it. And part of the reason why Boeing is investing in this is they see this as a path to testing what needs to be done to really put humans in an airplane that would be fully autonomous, okay? It's easier to start with a two-person airplane than a 600-person airplane. Okay, so that's why they're starting small. The two companies on the right, X-Wing and Reliable Robotics are doing a similar thing, but they're not even putting people in there, they're starting with cargo, okay? So they're taking Cessna caravans and converting them over for to be fully autonomous. I'll get back to a minute what I mean by fully autonomous, but no human on the airplane, okay? And again, it's a little bit easier because if the bags crash, die, they don't die, right? So the one on the lower left is Skyrise. So they're automating a helicopter, this is an R-66 helicopter, technically more challenging, but again, there's some things you can do with that that would be very useful, okay? One of the things that you see if you go back, so WISC, in addition to their airplane, has worked on what's called a CONOP. So this is, by the way, the very common thing in this industry is it's a concept of operation. So what would happen if you really were to go and fly this airplane? So, and if there's a document that they just published to get everybody on board, including the FAA, with how this is gonna work. Now the interesting thing if you look at it in detail is that they haven't gotten rid of the human, they've just moved the human off the airplane, okay? So a lot of the stuff that I show here is the human role in today's cockpits, okay? Has been moved off the airplane to the Fleet Operations Center. So we have good communications. So when you get to a hard decision, like, you know, I mean, by the way, if you're an airline pilot, one of the hardest decisions is somebody who's sick on the back of the airplane. Do you divert or don't? Don't you, okay? So these are things that are hard to write into a computer or software algorithm, okay? So things like that you sometimes need to call home for advice as to what you should do, all right? All right, let me go to my last example and then we'll go to questions, okay? Which is doing something totally new and important with the airplane, but also driven on sustainability. So one of the things that we did started about three years ago with, again, students at MIT in collaboration with Harvard and some schools in Portugal. We developed a high-altitude, long-endurance airplane system called the Stratospheric Airborne and Climate Observatory System. So this was a high-altitude solar airplane which was done to basically take measurements to support understanding of global climate change, okay? So that was the mission. There were a bunch of missions in there, but let me talk a little bit about these airplanes. So people have been trying to do high-altitude, long-endurance solar airplanes for a while. Okay, NASA did the Helios airplane, which, by the way, crashed in 2003. Okay, you can see the airplane. It had a 247-foot span, okay? All right, the span was a football field. There's a Facebook Akila that has a span of 140 feet. That also crashed, so these airplanes, in order to basically get the wing area you need for the solar cells, okay, need to, and to fly at these very high altitudes, need to be very, very, very light wing loading, okay? And they're basically these flexible structures that were very hard to put together. By the way, also a lot of people in this industry, and I do have that, yeah, yeah. So this is Aurora, this is a 243-foot span airplane, okay? All solar cells. Now, these airplanes were generally designed to be basically communication relay satellites. So they wanted to stay in one location, and they wanted to operate all year, okay? And this airplane got shut down before it flew. It was built but didn't fly. So one of the things you realize is that this was really tough. Now, jumping back to the mission, I was talking about, a lot of the climate change missions are driven by phenomena that occur during the summer. So what we did is we say, well, if we relax the constraint of operating all year, and only operate during the summer, does the design become more reasonable? The other thing is, in traditional, remember I talked to you about optimization tools, traditionally the criteria used for optimization is the weight of the airplane, because that's normally a surrogate for the cost and complexity. But we realized that the surrogate to optimize is actually the wingspan because that's a surrogate here for risk. So we wanted to reduce the risk of the airplane. So what we did is we designed, we optimized for wingspan, and we didn't try to do it, we only looked for summer months. So the upper right plot is a plot of required wingspan to fly a particular mission, okay? As a function of latitude and time of the year. And what you see, which is not a surprise, is in the southern hemisphere, right? In their summer, if you go to the poles, right? It gets easy. Now, by the way, I should have explained. The reason why it gets easier is you need batteries to get through the night, okay? But when you're at the peak summer time in the northern hemisphere, southern hemisphere, at the pole you have no night, so you don't need any batteries. Now, you don't quite get there. But the idea here is that you can make the airplane much smaller and lighter. So instead of, you know, 300 foot span airplanes, we're now talking 60 foot span airplanes, which are really reasonable. So we designed that airplane, and it has a bunch of minutes, so two motors. One of the other things is because the wings are so flexible, you can't use normal ailerons, okay? So the way we do roll control is you can see these devices out there that we call ailerons, okay? And what they do is they actually go the opposite sense. So use the aileron to intentionally twist the wing, and you get an increase in lift in the wing. So it's sort of a little bit counterintuitive. And the first mission that we're planning on this, or we're working up, is a mission to the Antarctic. So this is a collaboration with Brent Menchow from EECS, which is the biggest uncertainty in global sea level rise has to do with how fast ice will flow off the Antarctic glaciers. It turns out that these glaciers are being blocked by ice sheets that are on the face of the glaciers. And those ice sheets are breaking up. So there is a concern that they're suddenly are gonna break away, and you're gonna have a massive increase in sea level rise. And this is the biggest uncertainty. There is no way to go to the Antarctic and observe this in the resolution you need. We can do satellite observations, but they only update once a week. And for understanding the breakup, you really need to be there and watch cracks form in the ice. So the idea is to send this airplane down to the Antarctic to do that. So we've been doing development in it. In this summer, in collaboration with this company, Electra, we had student intern build the first prototype of the airplane. So this is the airframe that will fly in the stratosphere, okay? This is the first flight that occurred in August. You can see the Taylorons and the motors on the airplane. It was a quick build effort, so it doesn't have the full set of solar cells, et cetera. But this was the existence proof and we're now getting support to do the first stratospheric flights. And from the first stratospheric flights, then we'll go to the Antarctic. So let me stop there and open it up for questions and discussion. So I realize this is pretty broad, but I just wanted to hit lots of topics, so, yeah. For cleaner ways. Oh, I think we wanna... First of all, let's just give Dr. Hansman a hand. Thank you, John. Raise your hand and either I or Marina will run around and hand you a microphone, so. I was just curious. When it comes to like cleaner ways of getting the plane off the ground, are ionic or nuclear propulsion considered at all for this? And if not, why? Okay, so, all right. So there are some people doing ionic propulsion, but the problem is there's not enough thrust from the ionic propulsion to get a big airplane off the ground. So it may work for some small UAVs and things like that, but I think it just isn't gonna scale. By the way, part of the problem is that in order to get the voltages high enough to get a lot of thrust in the atmosphere, it'll cause a breakdown, which is like what you have inside a fluorescent bulb. So that's the technical challenge there. Nuclear, nobody's looking, as far as I know, of seriously nuclear on the airplane. And the reason is if you have an accident, you have a nuclear spill, it's ugly, okay? There are, I do believe that we're gonna see nuclear or fusion used to provide the energy that will either go into the batteries or the hydrogen or whatever. So I think the more likely path is use the nuclear power to go into a chemical conversion that you can fly on the airplane. It's my guess, yeah, yeah. What do you think about the viability of solid state or graphing batteries and how they would affect the practicality of electrical propulsion? Yeah, like the battery space right now is cool, it's the wild west, okay? I mean, the bottom line is from the airplane standpoint is performance. So first off, if you can get something that's not gonna go into thermal runaway, I'm all for it, okay, right? So if you can get to it. Cause that saves me on the packing factor and then it's all about energy density, right? So right now, people are about 450, the people are at the cell level, okay? And if you look at the trends, they're moving up, but I don't know how fast. So if there's some quantum transition, you could be there, but remember, we're 400, it's 12,000 on jet fuel, okay? So until you can do that transition to 12,000, so there's a big gap between where you are. So what will happen is the low-end battery applications will become more applicable, but I don't think it's gonna solve the problem. I think we gotta, that's why hydrogen or, I didn't talk about sustainable fuels, that's another option, we're gonna have to do something like that. Hey. Okay, this question may or may not be for investment purposes, but when it comes to taxis from what you've seen, do you think one company is better poised to take market share or is it really a risk to certification? So I think there's a bunch of, there is a risk to certification. I think people totally underestimate how hard it's gonna be to certify. The people who are probably in the best position right now are Wisk and Joby, okay? Joby, their advantage is they're vertically integrated and they're partnered with Uber, so if they can get certified to carry passengers, they gotta market, okay? I don't know whether they can make enough money in their market to pay for all the money they spent to do the development, but that's a business question. I think Wisk is another possibility because they're pretty far, so those are the two that are furthest along. Wisk is probably harder because they have to certify without a pilot where Joby is just trying to certify the airplane with a pilot. So I think there's, if you had to handicap them, I think they would probably get there first, okay? But there may be some other applications like say I have a bias interest in the Electra. I think Electra, on the certification side, Electra gets certified as an airplane, okay? And it's actually somewhat easier to certify as an airplane. Joby gets certified as this mishmash of tilt rotor, vertical lift, and airplane. So they're actually, three days ago or last week, they published the certification proposal in the federal register, so we don't actually, they don't even have a basis for certification. So it's, yeah, but we can have a long discussion, but it's tricky, so. Other question, yeah. I have a question. You mentioned thermal runaway. And I was wondering if that is a limiting factor because I see a number of applications for this spacecraft, this aircraft that you have designed. Especially if you're trying to monitor, say desert regions or countries with added climate. How would you imagine the impact of thermal runaway would constrain flights in those regions? Yeah. So it depends on whether it's a manned airplane or a human populated airplane or not. Okay. For a UAV unmanned airplane, it's probably easier. I mean, we're already at pretty high thermal energy densities. You may have thermal runaway. It's terrible, but you know, that probably you'd hurt someone. For human airplanes, airplanes with humans, you have to design for thermal runaway. Okay. So if I have a cell that goes bad, I have to guarantee that that airplane will not crash. That's actually gonna be a safety certification requirement. So that's the reason why the cells get to be problematic because I have to add weight to, the way I deal with that is I provide protection between that cell and the other ones. And it just adds weight and the thing gets to be hard. So you're in this area. That's why, you know, if you can show up with the graphene batteries that will do the trick, it's gonna make it much easier because I'm gonna get around that problem. Right. Yeah. You mentioned four electric aircraft and a hybrid electric aircraft and a hydrogen aircraft. Yeah. Like three different configurations. Which one you think is the most possible configuration that will serve the public transportation in the near future? So I think that, I think that the hybrid electric is the most likely to really be a practical airplane. Hybrid electric with sustainable aviation fuels is probably where you're gonna go for the midterm future. There are some battery airplanes will come in but they'll come in only at the very short range. Okay, right. And then I think in 100 years we'll be flying hydrogen airplanes. Okay, but there's a lot to be done from there. And let me say there's some non-obvious things on hydrogen. Okay, so on the, on liquid hydrogen, which looks really good, okay. One of the problems is for safety reasons, at least if you do it the way we do it today. Okay, when I refuel a hydrogen, when I refuel a launch vehicle, okay. One of the things I have to do is I have to make sure that I get the hydrogen out of there when I'm done. Okay, so I have to purge this system and I purge it with helium. And the reason why I have to use helium is helium is the only gas that won't freeze at liquid hydrogen temperatures. So you really don't have any alternative, okay. There is not enough helium in the world to do that. So when we've done projections as to the cost of a hydrogen operation, liquid hydrogen, 50% of the cost would be the cost of the helium to purge the tanks, okay. So there's the non-intuitive factors that get into that. Now we might be able to fix those technically, but those are challenges. So that's why they're further out there, okay. Other question, yeah. Quick question. Of the four or five-ish EV toll designs that you talked about, which one do you foresee being the most certifiable or most safe for the consumer market, the compound helicopter, the hydrostatic, or the tilt rotor? Okay, like I believe the Eastall, because that's the one I'm willing to be the test pilot on. Okay, right. Of the other ones, I think they're, they could all get there, okay. Obviously the easiest one is the multi-rotor system, okay. The volucopter's already flying, but if you looked at that, I mean that thing had 18 rotors, okay. It's not very efficient, okay. So sure, if you only want to hop across the river, so that'll work. I think that the, then the, like I say, the WISC and the Joby configurations both are there. It's hard to know the technical challenges or through transition. And by the way, one of the big problems in those airplanes that I didn't talk about operationally is the noise. So we don't know yet. Everybody's pretty close to the vest on what their real performance is. So we'll have to see. So it'll shake out. It's gonna be a very interesting time, right. There's a, I mean that's why it's a cool time to be doing stuff, because there's a lot happening. And the interesting thing from an airplane design standpoint is the electrification opens up the design space to configurations that, you know, we're totally, both a combination of the electrification and the flight control system. So I can use configurations that would never be realistic 30 years ago. So, other questions? Can I kill them? Ah, come on. There's one in the back. That's out of the room, John. They like you over here. Yeah, yeah, yeah, yeah. I'm scaring everybody in this side of the room apparently. Nobody wants to talk to the professor. Hi, so most of the presentation was geared towards like commercial applications of these new technologies and the pushes and pulls associated with that. Obviously, defense is a very large portion of the aerospace industry. So how do you see like the similarities and differences between these technologies in the defense sector and what are some of the other pushes and pulls that might be present in one space versus the other? Yeah, for these type of airplanes, there's some interesting differences. So for example, one of the applications that I've seen is for some of these things, that's a very useful Evito application is for medical evacuation. So you might have a unmanned, and again, if you're somebody in the battlefield who's critically wounded, you're willing to, again, the risk to get in a non-piloted vehicle and be a single person carrier out, automated kind of makes sense. So I think you see some applications like that. There's some applications on the stole stuff that is being looked at. There, you know, Joby is involved. There's a whole Air Force program doing some of that things. They tend to be more special forces type missions and things like that where you're trying to fly people in and out or support on sort of distributed island situations and things like that. So there's definitely applications there. There's a whole nother set of discussion on autonomy and unmanned air vehicles for military applications that go into other areas that are there, but probably be on the scope of what we can talk about here. Oh yeah. While partnering with Harvard and Portugal, how do you balance the ethics and promise of that possibly cutting edge project? Say a little bit more about the ethical concern. Ethical concerns, I guess, since the tech industry is becoming bigger and it could be used for other things besides what you meant it to be. And then also it's a very small sample size of what you've been able to do so far. Yeah. I mean, I think, I mean, technology can always be used as a voyage sword. I think that particularly this class of vehicle that we're talking about here that has very limited sort of adverse use. These tend to be used for things like surveillance missions and things like that. So I would say it did not come up as a concern to us. I think our bigger concern on this area is trying to convince people to really get the information to understand climate change in a way that will support action. Okay. Yeah. Yeah, sure. Do you think if you get a military contract with your project as it advances what is kind of the leeway between, like, do you give your project part of your project to them or do you kind of just keep it to yourself in the public sector instead of private? I mean, it depends on the, I guess I'm not sure exactly the context. I mean, everything we've done so far is in the public sector. Yeah. I was just saying I have family members that are in special forces and also do autonomy. Yeah, yeah, yeah. Autonomy, so. Yeah. When you bring this very possibly cut edge project, how do you, I guess kind of make sure it's ethically capped at one point so it doesn't get out of control when you possibly have a military contract? Yeah, I mean, I think different individuals have different views of what the ethical concerns are. I think the question is if you believe that there's a need for sort of military support, then there are people who will support the military. I think for me personally, I'm comfortable with sort of surveillance and support stuff like the electrostole is supporting special operations but is not a direct weapons source. So, I mean, but different individuals will have their own lines. Yeah, yeah. You mentioned Garmin Autoland. Yeah. That will just declare the emergency in the case of an incapacitated pilot. Yeah. When that system is in place, for example, the piloted aircraft that declares emergency, one of the first things ATC wants to know is the intentions of that aircraft. Yeah. So is there the functionality for ATC to actually interface with the system to understand the intentions of the aircraft or do they just have to vector traffic kind of away from that aircraft's head? So, as I recall, and I'm trying to remember the details of it, it squawks 7,700. So it squawks an emergency code. So air traffic in their own nose, the airplane has an emergency. And by the way, the procedures are for air traffic, they will vector, so whenever that happens, they clear the airspace in whatever direction the airplane's going. Because you can have that. And then at broadcast, and I can't remember, it may know the air traffic frequencies. I know it broadcasts on the common frequencies. In probably 121.5, that the airplane has an emergency and it is diverting. And I don't recall whether it actually, then, in the voice thing will say the airport is diverting too. But what it literally does is it finds the closest airport and it will fly to that airport and fly and approach and land in that airport and stop. So, and it was worked out, but like I say, it was a very interesting kind of non-standard project because it didn't fit the certification general rules. But what was argued in into, you don't have to meet them because you're already in an emergency situation. So you don't have to meet the standard normal operations criteria. Hi, professor. So I wanted to. I lost him. OK. Yeah, there you. Yeah, so you mentioned wing and ground effect vehicles. I was wondering, what are the potential challenges with those kind of vehicles? Yeah. So that airplane, by the way, I'm embarrassed I didn't. Let me see, find the picture of it. What's in here somewhere? Yeah. So this is the middle one here on the left. OK, it's a wing and ground effect. This is a company region. And what it does is, by flying at low altitude, because basically you get a mirror image of the wing underneath, you get an increase in your lift to drag ratio. You get more lift for the same drag, OK? So you get more performance out of the airplane. So it actually takes off on a hydrofoil, OK? So you can see the hydrofoil on the bottom. So it's a sea plane that lifts into a hydrofoil and then it pops into the air. The challenge with these are actually landing in high sea states, OK? So that you have to be able to take the loads and be able to fly. The interesting thing here is that these guys are trying, they may be too clever for their own good, but they're actually not certifying this as an airplane. They're certifying this as a hovercraft, OK? So it turns out if you're certifying as a hovercraft, there's some FAA regulations you don't have to meet, OK? So to make it a little bit more practical. But the reason why I scored it is better on sort of the overall performance is that because of the wing ground effect, you can effectively carry more weight at less penalty, OK? So it's a little bit more practical than some of the other battery airplanes. Question, yeah? You mentioned that safety was a primary concern in the application of highly automated aircraft. Can you speak to the impact of cybersecurity on the integration of this field? Sure. So there's a lot of people who, there's a lot of people and normally they're cybersecurity consultants, OK, who raise all kinds of cybersecurity problems for both commercial airplanes and whatever. So I would say today's existing airplanes are pretty robust, OK? The flight control systems are isolated from the rest of the systems. There's all kinds of firewalls are pretty hard to get to. And by the way, the input is done indirectly through a human, OK? So that's good. You do open up a vulnerability pathway when you start commanding the airplane from a remote site. So if you look again at the WISC con ops, they deal with that, OK, in terms of what the communication guarantee protocols and et cetera are. So there is obviously a potential concern that you might hack it. That is a known vulnerability. So in order to get approved by the FAA, you would then have to prove that you're robust to that, OK? So it's a failure mode that you have to consider. OK, with that, I think we're out of time. Let's give Dr. Hansman another hand for really engaging discussion of electric and automated