Solar Impulse Ends its Journey

feeling well. But today Jonathan and I are going to be talking about a subject that we've touched on in the past, and we're gonna come back and experience the fulfillment of an around the world journey of technology. Yeah. So back in April in two thousand fourteen, on April twenty three, to be precise, we published a podcast about solar powered vehicles, and we talked a lot about all sorts of different vehicles. Right, we talked about solar powered tanks.

Don't think we got quite around to that, but we got the cars and boats and and even airplanes. And we're talking about all sorts of different types of vehicles, including are different ways of using solar power from using solar power just as the primary means of getting energy to move the car to using solar power as a recharging station for electric vehicles, sort of a backup. Yeah, but one of the things we chatted about was this idea of a solar powered aircraft making a journey around

the world. Yeah, so you may have remember the name of this project. It was known as Solar Impulse back in the day. But we're sort of at the next level. It's one better. We've gone to Solar Impulse to write. The first Solar Impulse aircraft was impressive in its own right. We'll touch on that a little bit in this podcast, but it was the Solar Impulse too, that was the vehicle of choice to try and get around the world using only solar power as the source of energy. And

they succeeded. They did. They've just seated in a full circumnavigation of the globe in a completely solar powered airplane. Now, if if you haven't been reading about this and and you're like, wait a minute, how long did it take?

Did they ever land? It wasn't continuous, no, no, it was It was over the course of many, many, many segments and well well even kind of uh talk about just a few of those segments in particular, when something of real interest beyond I mean beyond just the fact that they did this incredible feat flying an airplane using solar power to generate electricity. Yeah, I guess I've read enough articles about Solar Impulse that I got kind of jaded.

I'm like, yeah, another Solar Impulse article. I need to remember to be astonished that this is a solar powered airplane. This is a heavier than air flying machine running entirely on photovolta excels. I still occasionally, when I'm on an airplane, We'll have that moment of this is incredible, and then I think, well, not only is this incredible, but someone

has created a solar powered one of these. Typically I am on a jet, not an airplane airplane, so it's not exactly the same thing, but it is really interesting. And uh, we'll talk about kind of the motivations behind doing this in the first place, Well, what happens next now that this around the world journey has come to an end, and some other interesting tidbits about the project here and there. But first we should kind of talk about where did this idea even come from to start with?

And and I actually went back and listen to that April fourteen episode because I want to make sure that when we did this episode, we didn't overlap too much, right, we didn't repeat ourselves, but really we were we were pretty uh, we were covering so many different topics in that episode that we didn't really dwell too much on Solar Impulse. So I feel okay about diving into the

background a little bit in this one. Uh. There were two people who were really the the heart behind the project, the people who kind of came up with this notion and decided to um to really move forward with it, one as Pinky and the brain. It's odd that you put it that way, and I'll tell you why, because one of them is sort of the technical expert and the other one was sort of the adventurer type. But they both have taken turns flying the Solar Impulse to

around the world. So the two people were Bertrand Picard and Andre Borschberg. Bertrand Picard was born in Lausanne in Switzerland and ninety eight, and on the Solar Impulse website if you wanted to read up on him, he is referred to as quote a medical doctor, explorer and lecturer and achieved the first ever NonStop round the world balloon flight. Oh I didn't even know he was also a balloonist. Oh yeah, No, he comes from a family of balloonists.

That is not even a joke. That sounds like it would be a joke, like, yeah, my family's into ballooning. It's absolutely true in the case Mr Picard, So this is this is uh, this is not our brain. This is our pinky. Here not to say that he's not intelligent, but he's he's he's our pinky. He's not the technical he wasn't the technical advisor. He's a psychiatrist. So clearly is already very intelligent. His father was an undersea explorer, his grandfather was a balloonist. Other members of the Picard

family include organic chemists and other explorers and balloonists. I mean, when you read about the family, you're thinking, this sounds like something out of a fantasy. And in fact, there can't be that many families of balloonists in the world, you would, Yeah, probably very few and far between. Bertrand's grandfather, August Picard, was the inspiration for a character in the

Adventures of ten ten. Yeah, there's a professor. There's a professor in in the Adventures who's this brainy professor type, and he was modeled in part on Bertrand Picard's grandfather. Why that professor? He makes me think inc of Trotsky? Does he look like Trotsky? I don't know that I would describe him as Trotsky looking. I guess. I mean, here's what I will say. The character is partly inspired by August Picard. I'm just trying to picture him. I

might have the wrong character in my mind. There's so many intintin to write. But it's it's funny that, you know, you talk about, yeah, these they sound almost like cartoon characters, and then you realize, oh wait, one of them kind of inspired a cartoon character. Uh. And. Bertrand himself did a lot of flying as a young man. He flew in ultralight aircraft, in balloons and in hang gliders, and he completed his circumnavigation of the globe in a hot air balloon in n So he had already set a

record before moving on to the Solar Impulse project. Like he had set the record as being part of a project to fly around the world in a hot air balloon. So he wanted to move up to something that was just slightly more high tech. Yeah, yeah, and and much more challenging in many ways from a technical standpoint, at

least endurance wise. It's probably pretty rough either way. But the other member, of course, Andre Borschberg, he was a graduate of m I T. So he's in his training is in an engineering that's kind of where his education was focused. And he was born in Zurich, Switzerland in nineteen fifty two. And he's also like I mean, if you read up on him, he is an incredible advocate

for a lot of social causes. Uh. He has dedicated a lot of time and resources to organizations like Rustos Decur which is or used to be known as Restaurants decor. This is actually a French organization that provides food to the needy. Um. He's also helped with social causes that benefit the sick. He's he's someone who is he's very outspoken about his desire to improve the lot of people around the world in as many ways as he can, and also has a lot of passion about the environment,

as does Picard as well. Both of them share this and obviously that played a large part into the decision to try and make a solar powered airplane, which you'd think was kind of crazy. Um he was sort of the technical department head. So yeah, he's our he's our brain. So when did they get this crazy idea to try to make a solar powered airplane that they could take

around the planet. Well, Picard kind of came up with it in two thousand two, and then he ended up talking with Boschberg and they decided to officially create a project called the Solar Impulse Project in two thousand three. So that was when they really started to say, well, what what's going to be necessary? What are we going to need in order to make this happen? And there were a lot of reasons that they were excited about doing this. Sorry, the thing that popped into my mind

is parachute. Yeah right, uh yeah, we I didn't put it in our notes, but I will touch on something interesting because there are certain questions that immediately come up of mind when you start hearing about how long some of these flights were, and I will I will go into some of that when we get bad pans, yeah, or the fact that well no, let's not let's let's

spoil it. I'll get there. Uh. So one of the reasons that they decided they wanted to do this, of course, was just the attractiveness of of setting another world record, right, creating a world's first. I mean, there could only be one world's first in any given category, and this was a way of doing that. So there's there's definitely that that sort of fame and explorer kind of side of the equation. Yeah, but this wouldn't be just a personal achievement.

Like anytime you demonstrate what can be done with renewable energy in a way that surprises people, I think that helps knock down some of the barriers that exist in opposition to greater investment in renewable energy like solar. Right, Yeah, that's precisely what they were seeing too. They were saying like, well, this is kind of like a a giant PR project to promote solar energy in particular and renewable energy in general.

And they also said, you know, by setting yourself a challenge, by giving yourself a definitive goal that we want to be able to achieve X, you then have to determine, well, what is necessary for you to get to X. It gives you something to work toward, which is a little bit easier than something that's open ended, like I want to improve solar cell technology. It's kind of like saying we're going to go to the Moon, as opposed to

we're going to develop our space exploration capabilities. Yes, and by giving yourself that definitive goal, then you have created like a laserlike focus on what is necessary to achieve that goal. And the nice thing is making those advancements ends up creating benefits that go well beyond just that specific project, and we'll talk a little bit about that

towards the end of this episode. So from two thousand three to two thousand and ten, they were really working on designing the plane that could fly not just in the daytime with direct solar energy. So it's one thing to create an aircraft that has enough surface area for solar cells to provide the electricity necessary to turn electric or to power electric motors that then turn propellers. That's

a challenge all on its own. Yeah, And we'll talk more about some of those design considerations in a bit, right. So the other part of that is how do you create one that can continue to fly when the sun goes down, because that that's been the big criticism. One of the big criticisms about solar power in general is that, well,

you're dependent upon the sun. When the sun is not out, you're not generating electricity, and so you have to figure out, well, how do you solve that problem for any application that uses solar power and not I mean flying a plane across the Pacific Ocean. That's a pretty clear engineering challenge, right, Well, yeah, electricity generation is a use it, lose it, or store it proposition. If you don't use it immediately or find a way to store it, it's not going to help you. Yeah,

it's just it's there, it's ephemeral, it's gone. Right. So they were able to create in two thousand ten the Solar Impulse one, the first of the aircraft, and uh demonstrate that it could actually fly through an entire day night cycle using onboard batteries to store electricity and then the batteries kick in once the solar cells are no longer able to pull the electricity necessary to power the motors.

And um Picard flew that mission. It was a twenty six hour long flight, so a day and two hours of flying, and it was again a proof of concept. They knew at the time that the Solar Impulse one was not going to be the aircraft to go all the way around the world. But it was sort of the prototype that allowed them to test the technology and make sure that in fact, it would serve when they needed to get to UH to circumnavigate the globe. UH. In two thousand, the two men flew the Solar Impulse

aircraft across the United States. UH. They took turns piloting the plane, and they traveled in several legs, so they would fly from one city to another city several hundred miles away, and then UH. Typically what they would do is actually switch off so that one person only one persons in the plane because weight is such a big consideration, right, So you got the pilot and that's it, and the other person would either take a commercial flight to get

to the destination or drive to the destination. Really you could probably run and yeah, I mean if you were yeah, these these plane, this plane does not go very fast in the grand scheme of things. But then you would switch off, you know, you go to whatever the next city is, and then the pilots would trade. And this was not can This wasn't necessarily like one flight right after the next either, Right, there was a lot of downtime between flights because for one thing, they needed to

make sure that the weather conditions were going to be acceptable. Yeah, that's a big thing, because this this plane's even though it's made out of some pretty interesting high tech material, ultimately you're still talking about a fairly delicate machine. And so you couldn't just and plus again, you need solar power. You need sunlight. So flying through like storms not a great idea with a solar powered aircraft. Usually when the captain says we can't take off in this weather, it

is a safety consideration. In this case, you literally might not be able, you might not have the energy necessary to achieve light. Yeah. So, but that that happened in two thousand thirteen, they were able to fly across the United States in this in this several legs kind of journey. And in two thousand and fourteen they officially started to work on the second aircraft, Solar Impulse too, and they began to incorporate lessons that they learned from the first

Solar Impulse aircraft. And this one would be the one that ends up flying around the world. That didn't start until two thousand and fifteen, and it went until July two thousand sixteen. So it's really took a year in several months. Yeah, it was a long process. This was not again, something that was done in one continuous trip. Um. So let's talk about some of the design considerations that

come into play when you're talking about a solar powered aircraft. Well, the most obvious one is the difference in the energy that you're using to power the vehicle. So in a normal airplane you would use to circumnavigate the globe, you're going to be running on aviation fuel. There are different kinds of aviation fuel, but most often it's a kerosene based jet fuel these days, and that's going to be

a high energy density, high quality fuel. Uh. And it's important for flight because heavier than air flight is not just energy hungry, it's energy ravenous. Um. You have to generate enough thrust to overcome the gravity of the entire planet. I mean, just think about it, and the planet is constantly trying to pull you down to it and give you a big earthy hug. Right. So it is rather earthy, isn't it. Yes? I guess it could also be briny, Yeah, I guess, depending upon what part of the Earth you

are over. Actually, it's more briny than earthy when you really get down to surface area. But go on, quite true. But yeah, so these are design considerations you'd have to factor in. So to lift an airplane off the ground, you've got to generate that forward thrust to to drive the the air and the way you wanted to go across the aerodynamic design of the airplane under the wings. Uh, so you know there are considerations like the wing span.

You can make the wings longer to generate more lift as you're trying to fly, but that also adds ways, right,

so you have to you have to make that. I mean, there's so much delicate math that goes into designing something like this where you think, all, right, what is the optimal arrangement of wingspan to weight where we're gonna have the large enough wingspan to generate the lift we need to get off the ground and and hopefully have the best wing span to uh improve the efficiency of flight so that you're not having to spend way too much

energy to maintain flight. Like you want to have the minimum amount of energy you need to continue to be in the air, but you don't want you can't go you know, you can't make a wingspan of indefinite length, because eventually you get to a weight that it makes it impossible for you to achieve flight in the first place. Structural integrity exams and that also is a real issue, right, like if you've got too big, then the ends of the wings would be so heavy that your aircraft would

break apart. Yeah. So this aircraft was powered by photovoltaic sils, as we said, so, yes, that's the kind that directly converts the sunlight into electricity, as opposed to other forms of solar such as solar thermal. Right, it's not it's not generating electricity through heat. It's changing it's when the photons excite electrons, and that's what you get with your electricity.

And it's just the big black mirrors that you see yep, yep, the kind that you would see on typically like if if if your neighbors, or if you have ever installed solar panels on the top of a house, that's typically the kind that we're talking about, right. So it's got a lot of those. It's got seventeen thousand two photovoltaic cells that are across the top of the airplane for

a maximum exposure. Yeah, and and those cells provide electricity to four thirteen point five kilowatton motors, and those motors each turn. Each motor turns a propeller and also provides charge to onboard batteries. So if you look at the Solar Impulse too, and you see this this plane with really wide wings, you'll see that there are the four

propellers in these little like rectangular casings. Those casings hold not just the propeller and the electric motor, but also the battery, the four big batteries that are on board this plane. So that's where they're balanced there along the wings, so that the weight is distributed just the right way, and that the propellers are positioned in such a way to provide the optimal thrust for the air craft. Now, those batteries have to be an interesting design consideration because

usually batteries are heavy. Yeah, these batteries are are They make up twenty of the aircraft's overall weight. More than actually it's more more than a quarter of the weight of the aircraft goes to those four batteries that are in that the wings of the Solar Impulse to do. Yeah, so let's get into the design here. So, yeah, this thing if you've seen a picture of it, and if you haven't, you should go look it up. There are some great photo galleries online and Solar Impulse, either at

stations around the world or in flight. It's cool looking. It's got a massive wingspan, gigantic. Yeah, it's huge, a wingspan of seventy two ms. And that is compared for comparison. I looked up the wingspan of a Bowing seven eight, which is sixty eight point four meters, So this is a one passenger aircraft that has a wider wingspan than

a Bowing seven Right. And uh, in case you're not up on the metrics, for one thing, if you wanted to switch it to yards, it's almost seventy nine yards wide, which means that it's getting pretty close to being as wide as a football field is long. I mean, you know it would it would if you were to put it in the center line of a football field, it would span a very good portion, pretty much to the

two ten yard lines. Yeah, it's it's pretty impressive. It's about two thirty six feet if you prefer feet to yards. Uh yeah, so huge wingspan, but on, but compare that to the fact that the entire airplane. According to those public facing material Solar Impulse put out, it weighs two point three tons. Okay, so that's a lot if you're trying to like lift it with your arms. Yeah, but that is not a lot for an aircraft. Compare that again to a Boeing seven actually, the weight of which

I couldn't find from Boeing itself. I'm I guess maybe we shouldn't consider it surprising that they don't want to share publicly the weight of their aircraft. But I did find an online aviation encyclopedia that claimed that the empty weight of a Boeing seven forty seven is about four hundred and seventy thousand pounds, which works out to two Yeah,

that's that's hefty, But think about the comparison there. So the Solar Impulse has about a hundred and five percent of a seven forty seven swing span and less than one percent of its empty weight. Right, So you already are seeing that they had to make some pretty uh dramatic considerations in order to make this a viable aircraft. Beyond that, you could say, well, how do they get

the weight so low? And part of it was the use of lightweight materials like various carbon fiber composites that are lighter in weight than stuff like steel and aluminum. But that's not enough. They also decided, hey, is this particular system necessary for the plane to get up and stay up in the air, And if it isn't, we're getting rid of it. And that's exactly what they did

when they started designing the Solar Impulse. They said, anything that's not specifically necessary to get into the air or stay in the air, we're not gonna put it on the plane. So do they have like the pilots weighing their breakfast that they before they take off. I'm certain that they had very specific like, uh, allotments for what food could be brought onto the plane because you have to eat. Some of these flights took more than a

hundred hours uh and that's multiple days obviously. So one of the other things they would do is say, like, well, you know, it would it would be pretty heavy if we had a system to pressurize the cockpit, so let's not do that. So the cockpit was unpressurized, also unheeded, unheeded. Yeah, there was no heating, rare conditioning in in that cockpit. Yep. You you were pretty much gonna need to make sure you were bundled up or able to cool off um or just endure it for the length of the flight.

And it also meant that they had to have um now, like they had to carry like a portable oxygen tank to occasionally take a good whiff because they're flying it. They're flying a decent altitudes like twenty nine feet. I mean, that's that's pretty high up there. So they were definitely, uh being adventurous in this approach. So anyway, these are these considerations weren't made lightly. It wasn't like they were

just being cavalier about it. They were making very tough calls on all right, what what can we expect to do without putting our lives at risk unnecessarily? Uh, and what can we what do we absolutely have to have in order for this to be a successful project and

not a terrible, terrible note in history. And that's a that's a tough call because these both I mean, clearly Picard had a history of adventure in his past, and you know, sometimes you might make a call that other people would say, well that just seems like that's too far beyond my threshold for risk. Right. But this meant that they got a plane that was at that two point three tons that wasn't wasn't as nearly as heavy

as other aircraft. And that's one of the reasons why it was a success, because they were able to keep that weight down, which allowed the electric motors to provide enough thrust to keep the plane going. So it kind of brings us over to the fact that we know we mentioned before the flying by night, like how do

you fly by night? Right? If you've got to fly for four days straight in order to go across an ocean or something like that, and if you can't, you can't just run on what's available at the moment, right, And if you're determined, if you're absolutely determined that solar power is going to be the source of your energy and you're not going to fudge by having a like a fuel based motor, backup motors and yes, some sort of engine as well as the motors, then you've got

to figure out, you know, how are we going to to continue to fly at in you know, the hours of darkness. And then of course comes down to those

batteries we talked about. They have four high voltage batteries aboard the solar impulse too, and the photovo take cells can actually generate enough electricity to both power the electric motors and recharge the batteries simultaneously, which was absolutely necessary on the very long flights, right because you know, you would get to a point where, sure, you might be able to make it through one night, but if you're not able to recharge that battery during the next day

and then you go into a second night, you run into some serious problems. So each battery is a seventy leader lithium polymer battery with an energy density of two hundred sixty one hours per kilogram, and their total mass is six hundred already three kilograms, And like I said, that means it's more than a quarter of the total

weight of the aircraft. So, uh, that to me is incredible that the batteries themselves make up more than a fourth of the of the weight of the entire vehicle, especially when you think of a vehicle that has a wingspan that that huge. Uh. They could store a maximum capacity of thirty eight point five kill what hours of energy of electricity, and they did did have a second battery, but that battery wasn't like a backup system or anything.

That second battery was a low voltage type of battery that specifically provided electricity to the cockpit systems, so you would have your navigation tools and things like that continued to be powered through that battery, as opposed to one of the ones that was in charge of making sure the propellers didn't stop moving. Um And if you look again at the picture, you'll see the little that they called him gondolas, the the kind of rectangular cubic sort

of containers that the propellers extend out of. They are pretty big. There was a great picture in one of the one of the pages on the Solar Impulse page that showed a person, an engineer, laying inside a gondola, clearly working inside of it on connections, and so all you see are the person's legs and feet sticking out from the end of it. So it was they're big, they're not tiny things, and the batteries take up a

good amount of space in there. And they actually partnered with a whole bunch of different companies to create this. It wasn't just Solar Impulse too. So in this way, Solar Impulse is a lot like organizations like NASA where they partner with other companies to provide materials or entire systems, depending upon what it is you're talking with. Yes, Yes, So this was not just two guys who went into

a backyard and built a solar powered airplane. One of the companies they worked with quite a bit was sulv a UM, they Solve. They did a whole bunch of different work on the Solar Impulse too, but they, for one thing, provided the material, the lightweight, sturdy material, mostly carbon fiber and carbon fiber fiber composites to create the

actual body of the airplane. They also provided a protective resin to coat the solar cell so it was transparent, but also provided protection in the event of the aircraft encountering bad weather or you know, any sort of dust or anything like that that it may have to move through from one region to another. You know, you're going around the entire world. That's a lot of different environments

you're going to pass through. Uh. And the solar cells were provided by a company called SunPower, and they were really high efficiency all things considered. They had an efficiency of twenty two point seven percent now compared to consumer solar cells which tend to be around twelve to. Maybe you might find some as high as twenty, but that would really be super high end on the consumer side,

two seven percent is pretty incredible. Now. That efficiency means that twenty two point seven percent of the energy hitting that solar cell can be converted into useful electricity. The rest of it is bouncing off or being absorbed as heat, just sort of the nature of solar. Yeah, it's we're never going to develop a solar cell that will be

a percent efficient. It is physically impossible. The I think the hypothetical limit from like a quantum uh level is somewhere between I want to say, I want to say is the absolute limit, but it's closer to like six for more realistic limits, and that's if everything were perfect,

which will never do anyway. Um So getting to this twenty seven is actually pretty incredible, even though it sounds low when you're thinking about percentages and you think twenty two point seven doesn't sound that impressive, but trust me,

it is. Uh. Then there were other companies. There was a company called Omega that provided lightweight l e ed s for the lighting for the plane, obviously very important when it's coming in for a landing, that kind of stuff, and there were others as well, So this was a group effort. Now let's kind of talk about the actual trip around the world. Well, yeah, so, as we mentioned, the Solar Impulse is a one seater. Yeah, so you

don't get to have a companion on this journey. Yeah, and this was the same as what I was talking about with the USA trip, where the pilots would switch off between legs, but it would mean that one person would take a normal flight over to whatever the destination was and await the arrival of the the other pilot, and then they would switch out and do that all the way around the world with some pretty significant delays in between some of those legs. That's got to create

a very weird looking like commercial flight history. Yeah. Well, there's gonna be one point in particular where we're gonna talk about some kind of an unfortunate but sort of funny, uh, set of circumstances that involves the more mundane aspects of travel. Well, so the two pilots were the same two pilots we

talked about before. It's the same two guys behind Solar again, right. So, Uh, as we mentioned before, the flight was not continuous that there were seventeen different stages of the flight that they spent a total of over five hundred hours in the air growing around the world, but layovers included. It took, as we said, over a year to complete the entire circumnavigation. Right, so five hours is around the twenty one days. So you think about your like, think about for for three

quarters of the month of February you are flying. Yeah, not, I mean for for for twenty four hours a day for three weeks you're flying. It's a lot of flying. I don't want to do that. I mean, you would hit executive platinum like no time at all, but that would be brutal. But you're not right in first class, are you? No? No, this isn't even steerage if there were such a thing for aircraft. Well, let's talk about the different legs of the flight because some of them,

some of them will just gloss over pretty quick. But a couple of them had some interesting stories. We came a price about them. So they started and finished in Abu Dhabi in the United Arab Emirates and uh so the first leg of the trip was Abu Dhabi too, Muscat, Oman, right, and I wanted to give you guys sort of a comparison, Like we talked about five hours in the air, twenty one day's total, and it took more than a year

for the whole thing to complete. But it's still kind of hard to put into your head, like how fast is this thing traveling? The answer is not very uh, And so I thought one way to do that would be to take this first egg from Abu Dhabi to Mascott and to look at the amount of time it would take on a commercial flight versus the time it took the Solar Impulse to to complete that trip. So if you were to book a commercial flight on Oman Air, that particular trip would take about an hour and fifteen

or an hour and twenty minutes. And keep in mind, you know, that includes all that whole taxiing business, you know,

the stuff when you're not actually in the air. So somewhere around a little hour and twenty minutes to get from point A to point b. Uh the trip, the distance that the Solar Impulse to travel, which by the way, is probably not the exact same flight path that you would see in the commercial flights, was about four eight miles or seven seventy two kilometers and it took them to Uh, it took the solar Impulse to rather thirteen

hours one minute to make the trip. So thirteen hours and a minute to go the same distance that a commercial flight would take in an hour and twitter. So yeah, that it's incredible. A thirteen hour You know. I've been on some flights where there's been delays, but I've never had an hour and twenty minute flights stretching to a thirteen hour one minute flight. Oh man, I don't. I don't like sitting on an airplane for a long period

of time. Um, I mean not. It is a wonderful modern luxury to be able to travel, yes, all around the world, so I shouldn't complain about it. But I'm I'm not so made as to enjoy long periods of sitting still without being able to get get up and go do something else. Yeah, especially not being able to do it without being a complete inconvenience to everyone around you. Yeah, because it tends to be the way it is on flights. Also, one thing that you do have an advantage of over

the pilots of the solar impulse too. This is a good time to talk about it because thirteen hours. That's a long time to go, right. If you are on a long flight, elaboratory you've got elaboratory you can walk to, but you better not try to smoke in there or disabled the smoke detectors. You are in for a for a weapon that you couldn't believe, or at least a finger wag. Right, it's a Delta Airlines State Safety video choke. Uh yeah, so on the celar impulse to of course,

there's single seater. There's no lavatory there. The chair, the pilot's seat, served multiple purposes. This was exactly a reaction in the April fourteen episode. I said, oh yeah, when I got to this part you and Lawrence, So yeah, it acted as the pilot seat, a cot for sleeping in, and a toilet. Yeah, which, by the way, I have a chair at home that serves those purposes too. It wasn't meant to that. I figured, with a little determination,

you can turn any chair into that kind of thing. Wait, so does it stretch out to become a cot or do you just sleep sitting on That is a question I do not. I think I think it may have reclined a little bit, because I would think just for some kind of strange psychological reasons. You need to be in a slightly different position for sleeping than the position

you're in for pooping and and possibly also for piloting. Yeah, yeah, so yeah, that's attractive to think about, right, the idea that you've got, you know, you know, but but you you couldn't have a lot of other stuff there because it would add weight. So it was it became a matter of necessity. Uh, not the most glamorous of things to think about, all right. So the first trip was Abu Dhabi to Oman, and next they went Ohman to uh Metabod, India. And here's a funny story. This is

what I was talking about with the mundane. So Picard lands in India and when he gets there, there's this big welcoming ceremony and there are a bunch of local authorities there, they are members of the media there, they all want to have their picture tag and they all are doing speeches. They're talking to him, they're welcoming, welcoming him.

He's getting this incredible experience. And it went on for so long that Picard was not actually able to go and get his passport stamped to move to to legally enter the country. They closed down the office the essentially the checkpoint where he could get his passport stamped, and so he was stuck. It was kind of like, you know, being stuck in an airport. He could not legally go

anywhere else. And so uh he was delayed, and that meant that he was not going to be able to catch another flight to go further into India and meet up with uh the other pilot Borshberg in order to do another switch, and that was to Varanasi, India, And so it became clear like he it was gonna make a delay, and this was a big deal because a delay in one place means delays all the way down the line. For It's not like they could pick up speed and make up for lost time. This plane was

not built for that. So it was it was legitimately a concern to them that they were going to have this delay, and there was not really anything they could do about it. They were kind of stuck in this this legal bureaucratic mess. It seems almost a metaphor for those times when a bureaucratic limbo interferes with the progress of technological achievements. Yeah, exactly. It's a great little way to point at it. I mean you part of you, you're like you understand where the issue is it. Well, yeah,

I mean you've gotta you gotta follow the protocol. But couldn't we have maybe had him get his passport stamped first and then have the big welcoming ceremony. Clearly no, so they were able to continue obviously. So the next leg was to Varanasi, India, and then there was a switch then um Mandalay in Myanmar, and then Cheong King or Chong Hing I should say, in China, uh non Jing, China, Nagoya, Japan, and then we hit the longest leg of their journey

around the world. Because what's after Japan. Well, if you're playing risk, you might go to come chat up across through Alaska. But they were crossing the Pacific Ocean. Yeah, and Pacific, by the way, is pretty big. It's a big ocean. So they were going from a Nagoya, Japan to Hawaii and this was the the longest expanse that they were going to have to travel in this solar powered aircraft. Barshberg was the one who piloted this leg, so I guess he got the short straw and Um

This was a record breaking flight. It spanned five thousand, five miles or eight thousand, nine hundred twenty four kilometers. Their maximum altitude was around twenty eight thousand, three hundred feet or eight thousand, six hundred thirty four meters, so pretty high up there. And the whole thing took them four days, twenty one hours, and fifty two minutes to

fly to Hawaii. So they just shying five days flying. Yep, that's a lot of poop napp And that's I mean, that's an endurance test, right, and that that also shows you have to have a lot of of confidence in

your aircraft's ability to stay on course. And you know, I'm sure they developed strategies for how long they should sleep at a time and then wake up probably regular intervals, to make certain that they're still on course and haven't drifted, or that the weather conditions hadn't changed in a way that was going to put them at risk. There are a lot of considerations you have to make when you're in that position. It is almost unthinkable to me, like

how complicated that had to be. I have trouble sleeping on a regular passenger airliner. Yeah, yeah, I understand entirely, and once they once they landed in Hawaii, they needed repairs. And this is also terrifying. They had to repair because the batteries had sustained dammit, they had been overheating. And so you know, anytime you're talking about a chemical battery, temperature can play a big role in how that battery performs. If you cool a battery down too much, then it

is very sluggish. It's not going to generate electricity at the rate that you would normally expect. Uh So that's a problem. But if it overheats, then the chemical reactions can start going, uh getting too fast. You end up losing capacity, so that even once the battery cools down, you can never charge it as fully as you did before. So then's a good reason not to leave your laptop in a hot car. Yeah yeah, because then you're like, hey, you know, it's weird because charge the other day lasted

me like six hours and now it's like two. Uh So, they obviously had to do repairs and replacement of a lot of of parts to make sure that they would be safe for the next leg. Because while the next leg was as long, you're still talking about multiple days over the Pacific Ocean, right, so they get to Hawaii, they have to do repairs. That slows them down a little bit. Then their next leg was from Hawaii to

San Francisco. This was a two thousand, five thirty nine mile or four thousand eighty six kilometer journey, which took two days, fourteen hours, and twenty nine minutes to make the trip, so not nearly as long, but still two days of flying two and a half more than two and a half. From San Francisco, they flew to Phoenix, Arizona, then to Tulsa, Oklahoma, then to Dayton, Ohio, and this

is when they hit another snag. So one of the things they had for this project was they had a portable hangar, like an airplane hangar to store the airplane when it wasn't in flight or when there wasn't a hangar that they could use in the location they had gone to. And this portable hangar was kind of an inflatable um UH building, So they inflated it had a semi rigid structure and they could park the airplane in there. In Dayton, Ohio, there was some problem where the hangar

started to deflate. Yeah, it was collapsing in on its plane with the plane inside it. So you've got this plane with this massive wingspan and this lightweight strong material. But it is very lightweight material. If you were to put too much weight on the end of those wings and they could snap or at least weaken the structure, which obviously would be devastating if that were to fail in the middle of a flight. So this was a moment of high anxiety and stress for the entire team.

They didn't know at first if the plane had sustained any damage, and so they had to take some time to make sure that, in fact it was still in good working order. Fortunately it was, but it did end up causing a bit of a delay and and set them back a little further than what they had intended. Uh. Their next trip was from Ohio to le High Valley, Pennsylvania, which is near Allentown. I've never heard of that before.

You never heard of Allentown or le High Valley. As I say, if you've never heard of Allentown, I got a Billy Joel song you Gotta Here, which is really depressing, but it's a song about Allentown, Pennsylvania. From there, they took off and landed in New York and then we hit the next pretty long leg. So they had already gone across the Pacific. That was the that was always

going to be the longest of their trips. But now they had another long stretch over ocean, this time the Atlantic Ocean, and they were flying from New York across the Atlantic to Seville, Spain. Now this took a lot less time than crossing the Pacific. The Atlantic is not as wide, or at least the distance between North America and Europe is not as great. But they didn't have a stop along the way here. Now this was straight flight from New York to Saville. So this was the

second longest leg. The third longest would have been the second part of the Pacific trip. The first was Japan to Hawaii. This would be the second one. The third was Hawaii to San Francisco. So this trip lasted two days, twenty three hours and eight minutes, so almost three days, and the distance traveled was four thousand, two hundred four miles or about six thousand, seven hundred sixty kilometers uh.

From Seville, Spain, they flew to Cairo, Egypt, and then from Cairo back to Abu Dhabi, where they started and that would conclude this globe trotting trip and um. But they were facing challenges right up to the very end. I read in the Solar Impulse blog where they were talking about the very last leg of the journey, and there were a lot of concerns. They were related to both, you know, the politics and the climate of of trying

to cross the Middle Eastern terrain. So they wrote, quote, crossing the Middle East is not as easy as you may imagine, which I already think of as not being easy. Yeah, there are a number of factors such as no fly zones, heat, thermal's talking about the thermal patterns right, like like updrafts of air from where, you know, the same sort of things that that large birds of prey would use to

remain aloft. Yeah, take off and landing conditions and wind, making this flight the most complex we have yet encountered. I would imagine, like just when you start looking at the different countries that they had to either pass over or stop end, it must have been a real effort to get the kind of permissions necessary to make this journey. I mean, just even the beyond the technical challenges, just the political negotiation you would have to do yeah, I

don't even know. I mean, I can't. Is it difficult to land a plane in Myanmar? I do, I don't know, But I'm sure that when you're passing through some of the countries they were talking about, there's you want to be real specific with your permission request to enter their airspace. And I guess it probably doesn't hurt that they're both Swiss.

That probably helps a little bit. But uh, and also you know that this was a a an endeavor to push solar power, and you know it's an environmental and scientific value to the project, which I think helps a lot of countries say yeah, we're all right with that. But still, I mean, I wouldn't want to be the person who's, hey, we hired you. Your job is to get permission for us to enter the airspace of all of these countries, like and keep in mind that some

of them don't like the countries. You have already been in peace on Earth and goodwill towards he who sits in the poop Cut. Poop Cut that it's gonna be the name of my band, poop Cut. Ladies and gentlemen, Welcome to the stage, poop Cut. So the total journey as we mentioned. Began in March, finished in July on July, so, uh took a long time. It was more than twenty six thousand, seven hundred miles or forty three thousand kilometers

in total. That's a long journey. It's a very long journey. Yeah, and you actually I like that you have a note here about what the average flight speed was on that final leg of the dree You think that you're thinking trying to cross the finish line right there, they're almost there, so they gotta be putting it a pedal to the metal. How fast were they going? It's thirty four point five miles per hour or fifty five point four kilometers per hour, and that you wouldn't think that you could stay up

in the air at that speed. Right. Well, it's those huge wings, you know, it's being lights having the design giant wingspan and uh man, that's uh that's impressive. Yeah, and uh you might wonder, well what comes next? I mean, we now that they've completed this this thing, they've been working on it for more than a decade, Well what are they gonna do now? Bertram Picard has said, quote I'm sure that within ten years we'll see electric airplanes

transporting fifty passengers on short to medium hall flights. That that sounds great to me, but I somehow have a hard time believing that that will be the case. Yeah, I mean it would be awesome if it was. I don't know how you could. You would have to design it so that the speed of travel is much greater to to make it worthwhile worth the time, Like, why

why is this commercially appealing? Yeah, because if you could drive to the location faster or as fast as the process of getting on a plane and flying, then why would you bother with the flying part? Right? I guess you could say for crossing water or something, it might be an alternative to taking a boat. Um, so that's possibility. And man, you could also argue that if you were to design like a luxury version of this, it could become kind of, uh, status sort of thing. But that's

not exactly commercial demand. That's talking about Hey, one per centers, how would you like to very slowly pass over the land that you rule with iron fist? You know? I would also think that fifty passengers, Okay, that's adding a lot of weight. Commercial passengers are probably gonna want lavatories, and yeah, They're probably are not so happy with the poop cut the drink carts and stuff like that. They will probably want heating and air conditioning. Um. So, I

don't know. It's a little hard to imagine. But one thing that I'm not trying to discourage it. I mean, I think it would be great if somebody could figure out a way to make this work commercially. I'm just trying to put the pieces together in my head. It's hard for me to imagine it being practical. I I think it would also be awesome if we could make it practical, because getting off a reliance for fuel would be great. I mean, we've talked about the environmental impact

of stuff like air flight and other shows. So um yeah, I would love to see it too. I don't know how practical it is, but one thing that is practical again is the fact that by making this engineering challenge and by completing it, they've shown what solar power is capable of doing, and with any luck, they've inspired more people to really take a serious look at solar power as a way of supplementing or perhaps supplying all of

their electrical power. And that would be amazing. Um. And we we've talked about that in other shows as well, so ultimately, you know, again it was get your names in the history books and also let's promote the heck out of solar energy and renewable energy. And I think they succeeded on both counts, so really impressive, and it was interesting to look at another kind of engineering challenge. Uh. We talked about that in like all the DARPA episodes too,

it's very similar. So this was pretty cool. I'm glad that we had a chance to follow up on it because when we recorded this back in two fourteen, I wasn't sure if it was ever going to actually happen. There were some times with weather delays and some of the mechanical problems where I was wondering if they were going to be able to complete it, but they were,

so congratulations to them. It's pretty cool. If you guys have suggestions for a future episode of Forward Thinking, or you've got any questions or comments, send them our way our addresses FW thinking at how stuff Works dot com, or you can drop us a line on Twitter or Facebook at Twitter where FW Thinking. On Facebook, you can search FW you Thinking in the little search bar. Our hopeile should just pop right up. You can leave us a message there and we will talk to you again

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