Are Electric Planes Finally Ready For Takeoff?

20:29 minutes

A view of the lower end of an aircraft.
A plane’s turbines. Credit: Shutterstock

You’ve probably had the experience of your flight landing, and as you wait your turn to deplane, seeing the ground crew running up to refuel the plane from a tanker of jet fuel. But could that tanker one day be replaced by a charging station, at least for some types of flights? 

Electric aircraft offer the potential of cleaner flight, with fewer emissions, as well as a quieter ride. Last week, Rolls Royce announced that a flight last November by their experimental electric propellor-driven aircraft “Spirit of Innovation” had officially beaten the world zero-emission speed record at 345 miles per hour. And on a more practical level, the company Eviation is set to test its nine-passenger electric commuter plane, named Alice, in the weeks ahead.  

Omer Bar-Yohay, the CEO of Eviation, and Mark Moore, the CEO of electric plane start-up Whisper Aero, join guest host Miles O’Brien to talk about electric aviation technology—and what it might take to bring battery-powered planes to an airport near you. 

Further Reading

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Segment Guests

Mark Moore

Mark Moore is CEO of Whisper Aero, based in Crossville, Tennessee.

Omer Bar-Yohay

Omer Bar-Yohai is Co-Founder and CEO of Eviation, in Arlington, Washington.

Segment Transcript

MILES O’BRIEN: For the rest of the hour, electric aviation. As the world looks to decarbonize transportation, aviation is the high hanging fruit. Transitioning from fossil fuels won’t be easy, but that doesn’t mean it’s not happening and may be sooner than you think.

Last week, Rolls Royce announced that an experimental aircraft it calls Spirit of Innovation has officially beaten the world zero emissions speed record at 345 miles per hour. The flight took place in November. And on a more practical level, the company Eviation is set to flight test its nine-passenger electric commuter plane Alice in the weeks ahead.

Joining me now are two electric aviation pioneers trying to help this movement take flight. Mark Moore is a former NASA engineer who has worked on electric propulsion for more than 30 years. He co-founded Uber Elevate and is now CEO of Whisper Aero. And Omer Bar-Yohay. He is co-founder and CEO of Eviation. That’s the company with the Alice commuter plane that I just mentioned. Welcome to both.

MARK MOORE: Thank you. Thrilled to be here.

OMER BAR-YOHAY: Thanks, Miles. Thanks for having us.

MILES O’BRIEN: Mark, you’ve been around for a long time in this business. There’s been a lot of talk about electric aviation for a long time, but in recent years, it seems like the pace has quickened. Give us a sense of how much innovation is underway in a lot of these small startup companies.

MARK MOORE: It’s funny how money will quicken the pace, isn’t it, because there has been a lot of money going into electric flight. You name it whether it’s the SPACs where the Jobys and the Verticals and the Lilium have each raised about a billion dollars to get their electric vertical takeoff and landing aircraft flying and through certification to the fantastic work that Omer’s doing with more practical and faster eCTOL. That is electric conventional takeoff and landing aircraft, which they’re just about to fly and everyone can’t wait to see it fly because it’s gorgeous.

And it’s emission free. So, yeah, it’s just– this is a new Wright Brothers era where there’s about 600 companies. Some of them are just small efforts in their garages but many seriously funded efforts to get all sorts of different electric aircraft from small recreational one person all the way to commercial transports. In fact, the largest one right now is being developed by Heart Aerospace at the 19-seater scale.

MILES O’BRIEN: You know I’ve heard the analogy. It’s not unlike Detroit at the turn of the last century when there were a lot of little shops and garages trying to figure out what the automobile would look like. Is that a good analogy?

MARK MOORE: That is an excellent analogy. And the reason General Motors is called General Motors is because they combined a whole bunch of companies together in a period of consolidation, and that’s going to happen for us, too. You’re not going to have 600 winners. Frankly it’s so expensive to certify an aircraft that probably there’s only going to be about five eVTOL companies that get through certification, and maybe five to 10 eCTOL companies that get through.

And, look, many of the smaller companies are going to consolidate or just go away. But it’s a really healthy period of innovation. You let the genetic algorithm run wild and try every single type of experiment.

MILES O’BRIEN: We’re talking electric aviation this hour with Mark Moore of Whisper Aero and Omer Bar-Yohay of Eviation. Let’s explain to people the challenge of electrifying aviation, and I know, Omer, you are deeply involved in this. It has to do– well, frankly a gallon of jet fuel pound for pound is an incredibly potent thing, and trying to match that with batteries is a challenge, isn’t it?

OMER BAR-YOHAY: The energy density question is definitely a big part of the problem, but it’s also a big part of the opportunity. It’s a different system, so you don’t need to look just at a pound per pound comparison. You need to look at the bigger picture.

And I think one of the beautiful things that as Mark very accurately said what you’re seeing is how much electric propulsion opens up the design space. You can do more things. You can put proposers and integrate them differently into the wing. You can create all sorts of weird shapes of planes. Some of it is trying to solve a problem. Some of it is trying to gain an advantage.

But you’re right, Miles, with the fundamentals. A battery today holds far less energy than the equivalent volume and weight of fuel. The motor itself, by the way, converts that energy to propulsion more efficiently, but that doesn’t even come close to compensate for that change.

On the other hand, the fact that we have both zero emissions, simpler maintenance, and that expansion of design space allows us to create new tools or new flying devices that do better than the prevailing design out there today for a reciprocating engine.

MARK MOORE: Miles, you know I hate it when you do that direct energy comparison because it doesn’t take into account so many factors. As Omer said, these electric motors are 95% efficient. A small turbo shaft or reciprocating engine is about 28% to 30% efficient so that there’s a three times difference in the efficiency or three times less energy that’s lost or required right up front. And the cost of electricity is less than these aviation fuels, and what’s really important is it’s far more steady.

Oil prices go up and down all the time, and it drives airlines crazy in terms of being able to have reasonable costs. Electricity is very flat and level costing and lower.

MILES O’BRIEN: So this is a key point, and, Omer, I want you to comment on this. An electric motor is much smaller. You can place it all over the airfoil, and that can affect the controllability in fundamental ways. But when you look at your aircraft, the Alice, it looks like those could be just plain old turbine engines in the back. And I assume this is– you got to start somewhere as Mark pointed out. Is this because you have to get through this process with the FAA and certification and it has to be a little more conventional, and down the road might it look very different?

OMER BAR-YOHAY: I think the answer on our end is all of the above. I think the Alice is a revolutionary plane from many aspects, but if you take two steps back, it looks like an airplane. It takes off from a runway. It has two props in the back. It has control surfaces that are fairly standard.

There are a few things we couldn’t get away with when transitioning to electric propulsion, and we had to hit a higher mark of efficiency. But as Mark rightfully said, there are more efficient way to have proposers integrated with controls and with lifting devices with the wings and create configurations that can do more things. The question is when can they do them safely and when can they do them reliably and can you get a product out the door in two years’ time from where I’m standing today or three years’ time from where I’m standing today.

And I think the interesting part is that it’s the right thing to do in the short term because there is so much learning and so much pushing on just getting the first Heart 23 light aircraft all fly by wire. No one did that before. Everybody’s talking about the Alice being the first commuter aircraft that’s all electric. That’s tremendous.

So that’s why I started the company. It’s my pride and joy. That said, I think the challenge of making this airplane all fly by wire is not smaller than making it all electric. And making this something that you can really bring to market in a reasonable time frame is the only way for a startup company to survive, and it serves a huge purpose because it opens the door for those next iterations and those improvements going forward. And it already has this tremendous role to play in an industry that’s just waiting to be revolutionized.

You called it the high hanging fruit. It’s definitely a fruit, and we can get there. So the question is how practical it is and how can it be certified and do you have the components. And that folds back to the challenges you asked about. It’s not just that there is less energy.

From a sustainable supply chain perspective, from a maintainability perspective, from a charging infrastructure perspective, there are so many things that need to be solved and done right for a plane to really be out there work safely like a workhorse, that getting something that can go to market in a certified way we believe is the most important thing right now and getting it to perform great and be the Tesla of the skies. It didn’t really change the car, but it was an awesome car.

And then can we do better going forward? Well, yes. And I think Mark’s company and some other efforts out there today really are showing the way.

MILES O’BRIEN: Omer, I’m glad you mentioned the car. When you get into the idea of penetration of electric vehicles on the ground, the big issue is range anxiety. What are the practical limits of range for a battery-driven aircraft at this point.

MARK MOORE: So it really depends on the type of electric aircraft. So for the eCTOL, the conventional takeoff and landing like Omer is developing, 300 to 500 range is what batteries can do today.

MILES O’BRIEN: And that’s miles, correct?

MARK MOORE: Yes. Statute miles. So if it’s an eVTOL aircraft, then they’re really limited to anywhere from 60 to 150-mile range. And a really important discriminator range is whether you’re flying visual flight rules or instrument flight rules. So, Miles, as a pilot that if you’re going to fly in all weather conditions, which is what commercial aircraft have to do, then you’ve got to keep a lot of reserve energy on board to do a 40-minute loiter plus an alternate to another airport. That almost half the amount of range available for an aircraft when you’re flying in non-ideal weather conditions.

MILES O’BRIEN: OK. So range limits the potential growth for all battery aircraft. One of the other issues which comes up, particularly when you start talking about these eVTOL, electric vertical takeoff and landing vehicles, which would be akin to the mission of a helicopter today, one of the big issues there is noise. And I know, Mark, you have spent a lot of time thinking about this. If, in fact, they become as ubiquitous as the visionaries in this space see these things– and then we’re talking about people who imagine millions of these craft populating cities, isn’t the noise potentially a showstopper?

MARK MOORE: Noise is huge if you’re talking about getting to scale, and scale is where great direct operating costs happen. So, yes. So after I left Uber Elevate, instead of joining Joby, which is an awesome eVTOL company, I decided to do my own startup. And for this whole first year the startup, all we did was reinvent and create the next generation of distributed electric propulsion that had specifically the goal of being able to be the quietest way to produce thrust ever developed.

And we have done that. And now we’re integrating our propulsers into different aircraft type that can be the most community friendly way to fly. So, yes, we think it is absolutely critical, maybe not in the first couple of years. But if you’re going to get the scaled operations and not just in urban areas– one of the nice things about urban areas is there’s a lot of background noise, so that’s one advantage they have. But they use a lot of power. So they make quite a bit of noise these, eVTOL aircraft.

For eCTOL, they’re taking off at small airports, but they’re flying over a lot of residential communities. So if you’re talking about doing 50 to 100 operations per day at a single location, you better be quiet or else you’re going to show up on a Google search like surf air San Carlo airport where mothers are holding picket signs saying your aircraft are waking up my baby. I don’t like this aircraft alarm clock.

MILES O’BRIEN: Something that needs to be solved for sure. Omer, another issue which came up in the course of the development of your craft, which was a setback, is the battery systems themselves. You had a thermal runaway which is a complicated way of saying a big fire and destroyed the aircraft. Help us understand what the challenge is when you’re using lithium ion batteries, and how have you solved that concern or attempted to solve it?

OMER BAR-YOHAY: First of all, thanks for the reminder. It was literally two years ago, and seeing the Alice kind of taxiing at speed on the runway just the 50 or 100 to 50 feet from me right now reminds us of how a good team can bounce back. Yes, we’ve had a lot of testing done to batteries and we’ve had intended and unintended fires happening every once in a while. The battery world and any storage of energy– if you come to think of it there is a risk in putting flammable combustible liquid in a tank and then burning it a couple of times a second in a piston chamber or in any other combustion chamber. So batteries as a chemical solution and a structure that holds energy has unpredicted or let’s say not safe ways of discharging that energy as well, and if mistreated or mechanically hurt significantly, they could combust.

The way to fix it is actually not that complicated, but it is very different than the way the auto industry, for example, treats a battery. The auto industry has the perception of what’s called a graceful burn or a graceful thermal runaway, meaning if I give you enough minutes to leave your car and your car burned, maybe it’s not so bad. This doesn’t quite work for aviation, and it doesn’t quite work for the systems that we want to see on airplanes.

With this in mind, we’ve created and I assume that anybody who wants to be successful in this space right now will have to create not just a set of systems that test batteries to the point that sometimes they burst into flames and then you model it and make sure that you know to handle it, get rid of the energy that that’s exhausted, and not make it not allow it to propagate but also battery manage and prevent. And that combination is really the heart of any safe propulsion system that’s battery driven.

Getting there has a lot to do with the scrutiny coming in from the regulator. There are a lot of standards in place how to do this right and how to test it but also has a lot to do with our ability as an industry to look at the battery cell and to build on top of that. The cell has its own characteristics. And it’s a lithium ion cell, but that’s the high level declaration. There are so many specifics and differences in the cylindrical cell that Tesla uses and in the pouch cells that other car manufacturers use you have different ways to handle thermal runaway. And those need to be explored, built, and then proven to the point that, A, you didn’t have too much overhead in terms of the safety systems on board, and on the other hand, you created the system that is safe to allow that repeated safe operations that we want and need to expect from the aviation industry.

MILES O’BRIEN: I’m Miles O’Brien, and this is Science Friday from WNYC Studios.

So, Mark, let’s talk for a moment then about the regulatory process here. The FAA doesn’t have a ton of experience certifying electric aircraft. So what’s that going to look like? What sort of timeline is realistic? In short, when are we going to get into these aircraft? Is it sooner than we think or when you get into FAA regulations? Sometimes I can rock on for quite a while.

MARK MOORE: We are getting very close. And first of all, look, the FAA vehicle certification division is doing an excellent job facing these new technologies. So I firmly believe from everything I’ve seen and heard that you will see electric conventional takeoff and landing aircraft certified within the next two years. I think Omer’s on a path to do that. He can disagree. But I think the electric vertical takeoff and landing aircraft are on track to certify by 2024.

The wonderful thing is that both of these types of aircraft will be certified through what’s called Park 23. It’s for small aircraft, and the FAA did an excellent job getting ahead of things by essentially rewriting all of part 23 to be able to utilize consensus standards, ASTM and SAE, other standards. So essentially these are ways, for electric motor, a standard way of ensuring that it’s safe for batteries, a standard way to ensure that it won’t go into thermal runaway.

So previously, a couple of years ago, the FAA could not use these performance standards. You had to follow their prescriptive recipe for how to certify, and it was cumbersome, complex, and just not a great way to do business. So thank goodness that now we can all use these performance standards and be able to benefit from them.

MILES O’BRIEN: Unfortunately, we’ve run out of time, gentlemen. Mark Moore is a former NASA engineer who has worked on electric propulsion for about 32 years, he co-founded Uber Elevate and is now CEO of Whisper Aero. And Omer Bar-Yohay, he is the co-founder and CEO of Eviation. Good luck with the upcoming test flights. Keep us posted. And thanks to you both for joining me today.

MARK MOORE: Thank you, Miles.

OMER BAR-YOHAY: Thanks so much for having us.

MILES O’BRIEN: And if you want more on the world of electric aviation, I recently filmed a Nova episode on this topic, which we talked about briefly. It’s called the Great Electric Airplane Race. You can find a link to that at sciencefriday.com/electricairplanes.

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As Science Friday’s director and senior producer, Charles Bergquist channels the chaos of a live production studio into something sounding like a radio program. Favorite topics include planetary sciences, chemistry, materials, and shiny things with blinking lights.

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Miles O’Brien is a science correspondent for PBS NewsHour, a producer and director for the PBS science documentary series NOVA, and a correspondent for the PBS documentary series FRONTLINE and the National Science Foundation Science Nation series.

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