Profile: SME Interview on the Technical Path for eVTOL Technologies (Part 1)

Martin: So what we're seeing in the past couple of years, since eVTOL has really come to the forefront of advancing aerospace technology, is a lot of the knowhow it's come across from experience with electric vehicles and electric cars, electric trucks, as you say. So even down to the employees. We're seeing it coming from that market, that industry. And knowing what eVTOL companies know and trying to get to the market as quick as possible, they really have repurposed a lot of the technology.

A lot of the architectures that they are used to designing, manufacturing, and us as consumers using, are these electric cars. So typically technology wise, performance wise, we're seeing similar kind of battery packs running at a similar kind of voltages of 400 in the very kind of base level for electric vehicles up to 800. That's where the aerospace, electric aircraft tend to be operating right now is around the 800 volt system. Really employing kind of the very simple architecture of a battery, a power distribution unit, and inverters and motors are being carried across and ideally optimized, for the specific aerospace architecture into what we will see with these eVTOL and eCTOL aircraft. But obviously there's a lot more of the motors involved, and these aircraft are a lot more power hungry than electric vehicles.   

So you see a lot more battery packs. You see a lot more motors, and ultimately a lot more redundancy in electric aircraft because obviously with these cars, when you drive a car down the street, you can you have an issue, you run out of charge, you kind of pull over to the side of the road and you get rescued. But now when you're flying a few thousand feet up in the air, you don't really have that luxury. So we have to bump it up in terms of safety, in terms of robustness. So you tend to have greater redundancy of systems, you have more battery packs powering different configurations of motors. You tend to see aerospace-grade components in the safety critical architectures to ensure that these vehicles are safe to fly. So it's been quite a learning curve, particularly for those in the startup organizations to kind of come up to the aerospace way of working. Working with the agencies and the authorities and regulatory bodies for aerospace. So it's really interesting time of how we're kind of melding aerospace and automotive technology. So there is a lot of similarity. But at the same time there's quite a bit different, because of the standards and the safety aspect. 

Matt: When you think about electric cars, electric trucks, and compare them with electric aircraft, we're now defining this in a three-dimensional space versus a two-dimensional space. So when you only have to think about, you know, driving on a road and, and your steering wheel versus lift and, and navigating in that between buildings and power lines and stuff like that. So the types of systems that are required to fly in that vertical type of space require additional systems and especially sensors on the motors and propellers and things like that, which you probably don't have that level of sophistication in the car driving vehicle. So what does that mean for again, safety is even more critical. 

Matt: Great question. So in when we think about eVTOL architectures and think about the vertical aspect of it and compare that with traditional aircrafts, aircraft will have a generator creating electricity on an airplane. So if you think about just flying commercially, you have every comfort available to you. You're entertained and all that's running on electric. You're communicating the avionics systems. That's all based on some batteries. But on the engine you have a generator. So the generators typically creating often a three phase power that comes off of that AC power. And when we deal with eVTOL, especially the pure electric aspects of those, you have many, many batteries that are responsible for the takeoffs and creating that lift feature, and also at cruise, and then also any other avionics system or comfort system on the aircraft. So what we're seeing is the batteries create an issue in that when you fly batteries around, they're not getting any lighter.

When you fly traditional conventional aircraft around, they are burning fuel, consuming fuel and also creating more efficiency as you fly. So one of the main challenges with the electrical architecture is to design things efficiently, especially with heavy batteries, and where you place them to enable optimum flying characteristics. And what we're also seeing with the architectures is the power required to get lift is very, very high. You're talking megawatts of power. And power is a function of how much amperage and voltage you can put through your, your cables and connectors.   

And so if weight is already an issue and current is typically related to how big the wires are, you don't want your wires to physically get bigger because A. they won't fit, and B. they're very, very heavy. So the other lever you have is voltage. And when you create higher voltage, that creates a, relatively speaking, a very dangerous situation with high voltage. Think about lightning bolts and the amounts of voltages in those forces of energy. And with the voltages we're looking at, they're pushing around 1000V. So that's a very, very high voltage. So the insulation materials have to be extremely robust. If you have any kinds of scrapes on a cable or something that creates a failure mode with high voltage, it's very, very dangerous. So in these architectures we have to consider safety especially the other part is how do we charge. Or how do you get that energy? So the charging systems is something that has to be thought through in the infrastructure you're flying around. So whether it's an airport or let's just say you land on a building, you need to have the ability to get charging. And charging, I would say, is a key piece of the infrastructure that we still have to develop with the eVTOL.  

Martin: So this is a great question. I mean, this is a fantastic question for future MBA business students. They're going to look at this market for decades to come to the kind of really talk about what's happening here. So, if this goes right back to the early days of the automotive industry, the 1900s and 1910s, when you had hundreds of motorcar companies, motorbike motorcycle companies out there and names that are kind of now consigned to the history books but sometimes live on in different generations. So why are things happening the way they are? Well, essentially this market is completely new. We haven't seen anything like this before. One thing you shouldn't think about eVTOL is that it's electric helicopters. It really isn't. Now, what we're seeing is perhaps a three to five time reduction in operating costs. And if you remove the pilot and we go fully autonomous, we should start seeing price points for consumers that are very similar to taking a taxi across the city, or they're taking a train fare from one city to another. And it really is down to how this this market is kind of growing. So it's finding its feet. And right now, we're in this kind of first generation of market leaders where again, a lot of them are startups. So they are working to their investor time frame demands. And finding the right business model itself.  How is the public going to access these aircraft? What is that business model? How is going to be validated? What is the mission profile? I mean, people are expecting to see a revolution in mobility. Uber elevate did a great job many years ago to kind of really kick off this industry.   

It showed a future potential out there of what the public could be doing with urban air mobility and electric aviation. Electric aerospace. So what we're kind of seeing is a bit of, it's kind of Darwinism almost, as a lot of these kind of use cases get understood, the customer base, whether you're looking at doing freight or cargo, whether you're looking at doing a paracivil type application of security, or fire service, or emergency service operations, or whether you're doing a passenger commuting or transfer. How you do that in last minute, last mile kind of, delivery services or middle distance or longer distance and whether that regional, or whether you do that across cities or across lakes or across mountainous regions. All that kind of plays into shaping what these aircraft are. How long are they going to fly? How far are they going to fly, how much payload, whether it's passengers or cargo, kind of comes down to many, many niche markets. So that's one aspect. That's just a market aspect. And then we're kind of looking at the technology. So I kind of mentioned earlier there's a lot of this technology is kind of transferred particularly batteries in from automotive into the aerospace domain.   

So as we grow that that technology, as we learn more and more and make these batteries more efficient, the chemistry more efficient, the packaging more efficient, the connectivity more efficient, not just in the batteries, but in the high voltage system. We start designing specific eVTOL optimized components. And I kind of like what we are doing now. You can see efficiencies there in weight. You see efficiencies in assemblies, the efficiencies in packaging, that these aircraft demanding. You can see this gradual evolution from this first generation of trying to find out how it's going to be using current technology, through the industry as it matures, as the market matures, then start looking at how can you make the architecture efficient? How can you go up in higher voltages? How can you address the market more, as, you know, essentially you start creating a demand for the market. Because this is so new, you're going to open up different mobility options for people. You're going to be able to connect cities today or in very near future, that take just half an hour to get across where, when the road system or rail system takes many, many hours. Norway comes to mind in particular, for example. So, yes, the reason why this is all really taken a kind of many iterations is there's a lot of learning to be done, not just in technology, but in the market application and who the customer is. So super exciting. And this will continue for many years to come.  

Matt: Another really good question. And this is why, at least at TE, our approach is to think about our aerospace products and components that have decades of proven industry performance and redeploying those types of products and materials. There's something in aerospace called the TRL level or technology readiness level. And that's very important to understand when a new component is proposed to be used. For example, if it's used in an electric car, you know, what's the difference in the environment when you use it in an aerospace environment? And what's the expectation of reliability of those components? So as we think about the different architectures and the iterations of aircraft, there is a lot of learning going on. And when something fails, it makes big news. So you don't want to have something, if it fails, you want it to fail and perhaps a test environment. So when we think about even the structures and traditional aircraft, the propellers are usually mounted on the fuselage or very close to the fuselage. And some of the new designs that we're seeing, the propellers are mounted further out on the wings. And they're not just mounted further, they have articulating motions on them. And so we're seeing a lot of different things as they do test and flight. You know, our cables have to connect to electric motors means they have to have a different level of flex endurance.   

Typically in a in a traditional aircraft, you're not going to see that type of flexing. The route ability in tight spaces means we're looking at new geometries for cable, and all these have to be validated and tested. So over time, you know, we do have a long pedigree and a long history. Very good pedigree, a long history of the types of materials that we've been using in our connectivity products, our power switching products, and also our wire and cable products. So we have many tests that we already do that are industry standardized, that the industry has helped us to ensure the durability of flight over time. And these are things like how does it handle the temperature ranges, whether it's hot or cold environments, how does it handle the typical chemicals that an aircraft will be exposed to? For example, any kind of fluids which typically aren't going to be around electric aircraft, but they will be around typical airspace environments. There's other things like de-icing if it has to fly in a cold environment. So those are just a few of the aspects. There's a lot of testing done around salt environments. So salt can be a catalyst for a lot of things including corrosion and things like arc tracking on cables. So we had to be very aware of these things as we deal with the higher voltage and doing electric flight.  

Matt: Yes, a battery is a really interesting area because, as you know, with a lot of the devices you use, the battery energy quality at a full charge is not the same as the energy quality at a very, very low amount of charge. And so if you think about flying and you think about when that low battery light comes on and you're flying and do I have enough time to land, you know, that makes that will make, you know, the passengers very, very nervous, I would think. And you know, so the quality of the connections are very important, especially in vibration and making sure that every, every connection, literally every connection counts as, as you think about this core energy supply in flight. And so when we design our connectors, we want to have efficient, material usage in there. And the function of current carrying capability is a function of the cross section of the material and the conductivity of the material. And also the shape matters as well with heat transfer. So we spent a lot of time into designing these optimally to make sure you get the less loss of energy connecting to the battery.    

Matt: So one of the, I would say new aspects of electric motor connectivity, it depends on where the motor is mounted and if it has to do things like articulating during flight. So, typically it would be mounted in a position to enable the vertical part. And then it would articulate so it can do the translation part of the flight. And so when we talk about our cables and how we rate them and thinking there might be thousands of flexes during one flight, that now becomes probably a maintenance issue. And so enabling quick maintenance on aircraft is important. And also being able to do inspections and understand the life of any kind of component in terms of what's the span of maintenance period for it.

So these are some of the things as we deal with high voltage and when high power and high voltage, as I mentioned before, when it fails, it fails very dramatically. It's, you know, lightning bolts that could, you know, arc to different surfaces. So we have to be very careful as we do these designs and test them and make sure that the electrical motors, some of the other aspects we do in commercial aerospace is designed for what if it fails? For example, if a motor would fall off, what happens to the cable? Does it rip out of the airplane? And we make some special terminals that are designed to even break so it doesn't pull the cable through. So there's a lot of very unique things that we can offer for electrical motor connectivity. 

Matt: Another good question. And the electric motors are controlled typically by an inverter that's hooked up to a power distribution unit. So the battery is the source of the power. And then it goes into a power distribution unit that will control the types of power being run to different systems, whether they're avionics or the propulsion systems. And today, with the types of power that we're talking, the megawatts of power, we need, new types of switching control. And today we're doing this, both with traditional electromagnetic controls, but also in the future we're developing solid state controls. So what that does is that enables a better reliability because it doesn't wear out the contact surfaces that are doing the power switching. It can have things like fault detection embedded into the electronic controls. And these are things that I think for the future are required to do things more reliably, safely, and enable electric flight. 

Matt: Another great question. So when we go from prototype to production or even before that, from concept to prototype to production, we think through how we would build an airplane or aircraft and routing things like these cables. Once they get these in hand and see how difficult it is sometimes to route a heavy power cable, we now have to rethink how we do build things to scale up for production. So what we've learned over the past two years is going from just the concept of getting something into air to fly. And then we get the concept of okay, how do I now scale this up to make potentially hundreds or thousands of airplanes? And the other thing they have been evaluating. again looking at perhaps automotive grade products and can they be used and that's the cables, the connectors, the power switching types of products, the sensors, maybe even fiber optics. They can now translate into using some new technology that can help save weight, not just get something off the ground, but to fly efficiently. So when we think about this whole transition, we're learning a lot with what works. We're learning a lot from the aerodynamics perspective and the aerostructures perspective. We also have to consider the whole maintenance philosophy. Again, how we do charging and all this? Do you take batteries in and out, or do you hook up to a power cable? So I think there's a lot of things still being learned. And those are some of the gaps. So the infrastructure of how do I do quick charging, where are those charge access points going to be? And all this still, I think, is being discussed in the electric flight community. 

Martin: So it's really interesting here because there's kind of two forcing functions. Firstly is the huge desire for aerospace or aviation to limit their carbon dioxide emissions. And there's governments worldwide are looking to use legislation and regulation to ensure aerospace does its part. We recently see the introduction of sustainable aviation fuel. A lot of hydrogen testing with running of gas turbines, for example. Electrified aircraft are part of that, whether it's hybrid or fully electric, there's a lot of work going into ensuring that these emissions, whether it's carbon dioxide or NOx or no noise are reduced. We see a lot of incidents where traffic is being lowered. For example, in Holland, the Schiphol airport is limiting the number of movements for aircraft, particularly business jet. And we see in France where, where there is an alternative to go by high speed rail between cities, domestic flights are banned. Even if the rail ticket is two or three or even greater times for the paying customer. So we're seeing kind of a lot of legislation happening to, to reduce that. So that's one area where there's going to be a drive for electric aircraft. And secondly, the big driver for that is it's kind of offering up this, this greater mobility option to people. And some of the first incidents of business cases, use cases for eVTOL was, was getting across town.   

And Sao Paulo is one of the largest cities in the world, and it already has an urban air mobility option through existing helicopters. And the effect of that is you reduce a 2.5 hour commute from the airport into the center of Sao Paulo to something like 20 or 30 minutes. Today we see helicopters in Manhattan, ferrying people five minute flight between JFK and downtown Manhattan, which can take an hour, typically by road. So that's kind of the very first kind of demand option where has already said that the 3 or 5 time reduction in operating cost for, for mobile transit through the air is going to be offering high speed, reliable, and safe flight for, for pretty much everyday people. Then it comes to kind of connecting communities. And once the market, once the industry starts showing that there are options for people, certainly in places where the road and rail infrastructure isn't quite there. The UK is one of them, where we can offer up regional transportation. Across Florida, for example, another use case, across Norway is another, UK is another, I think that goes across lakes and rivers, seas. The Caribbean is another one where it can cost several hundred dollars for a 20 minute flight to go between islands. So it does offer up kind of everyday opportunities for people. And that demand isn't there yet because it's kind of seen as not available.   

But once it starts happening, it'll be a self-generating demand. Options start opening up. But in terms of what the limitations could be now, there have been various studies on this, throughout the European Union and other cases, in the US where companies have done [eVTOL companies] have done their own research. Some of the big worries is noise and how noisy are these aircraft going to be? And there have been some great demonstrations of how just how quiet these aircraft are a lot, lot quieter than, than turboprop general aviation and helicopters almost to speaking level as it flies overhead. So very good to see. Safety is another aspect. So, are these aircraft safe to fly? And that's very key thing. They are aircraft. They are not ground vehicles. They are not electric cars. They're not electric trucks. So they do abide by aviation safety rules, which are incredibly safe, and it's the safest form of transport nowadays. Another topic is access is kind of interesting here because it's not just about giving people a way to drive to a vertiport or, or how they get their taxi to an airport and then away from an airport to their place of work and in the center of town, or for example. So it's not just about access there, it's about financial access.   

How do you make this accessible to perhaps not just a group of elites, but make it accessible to individuals at a lower income level, but also in terms of physical and mental ability as well. So are these aircrafts accessible for wheelchair users or those who have personal space issues. And one of the issues I was kind of brought to my attention was how autonomous vehicles perhaps are not appealing to women users because of the lack of someone in authority in a vehicle, which I thought was very interesting. So how can we make these, these aircraft fully, fully accessible for everyone? And of course, now kind of going back to the safety and reliability aspect, we've got to make sure these aircraft are robust and demonstrate that to people that they are safe to use in every way. So safety, reliability, noise, making as these aircraft as little impact as possible to people today while giving them greater mobility access than they have today. Can we get them both? I think we can. I think we can get both aspects here with careful design work, working with providers like ourselves to look at optimizing components and subsystems, to really kind of help, as I said, the evolution of this industry going forward, there's a lot to do. And it's super interesting and great to be part of it.  

Matt: One thing that I think would really help to drive market adoption is the whole cargo area as well as military. And this is an area where they can do a lot of training and get a lot of that required flight time hours in a very low risk environment by moving cargo around with some of these eVTOL type vehicles. Some of the limitations I would see with market adoption are the ride experience. And you know, when people are used to a commercial aircraft ride experience, it's designed to be very comfortable. And, you know, perhaps riding in an eVTOL might feel like more of a roller coaster ride or something like that. And as an outsider, think about sitting in a cafe in Paris enjoying your coffee and croissant, and all of a sudden this eVTOL comes down, blows a lot of wind, dirt and debris everywhere. And people may just have a different feeling about that. And not just that, but in addition to those factors, but also privacy. So if you have access now vertically into different spaces, maybe your own backyard, and maybe your neighbor is flying his eVTOL, maybe you want some privacy that is now intruded upon with this type of aircraft. So these are just some of the other aspects that could be considered with market adoption. 

Martin: Yeah, you make a good point, Matt, because I fly small four seater general aviation aircraft and you can get quite a ride in those on crosswinds, especially when you're coming to land. So yeah, that's another part of it is how comfortable are you going to be in these very, very stiff airframe, vehicles. You're going to get a lot of turbulence around, skyscrapers, etc. if you're not careful. So yeah, that ride quality is important.