TechStuff Classic: Flying Without Fuel

let's find out. We wanted to have a chance to chat about something that I talked about in a recent episode of Forward Thinking. So if you guys haven't checked out Forward Thinking, please do. I think I think a lot of tech Stuff fans would really enjoy that series. Joe is the head writer on Forward Thinking and has done amazing work. I have not written this episode, however, this episode was I thought really cool. And it's a

about a solar powered aircraft. Yeah, which, when you think about it, that on its face sounds pretty crazy, especially if you have taken time to really look into solar power and not just its advantages but it's limitations. Right right, Well, this is obviously not the only solar powered aircraft that's ever been created, right, it's it's probably the coolest one ever created yet. And it is amazing that you can take a huge, heavy thing off the ground with the

power of solar energy alone. That's just I mean, this is what powers your calculator, right, not not an airplane. Yeah. Like, for example, I have a a battery pack in my in my backpack solar panel that it faces outward, and in theory, you can use solar energy to recharge the battery pack, which then you can use to recharge something like a smartphone. Right, that's the basic premise of this backpack. Here's the thing. If I want to recharge that battery using solar power, I have to have it in the

sun for twelve consecutive of hours. One doesn't have to be consecutive, but twelve hours to get a full charge. Whereas if I were to plug it into the wall, it's an hour and a half maybe two hours total to charge it all the way up, maybe even less than that. So it just shows that that solar power, you know, getting a lot of energy from it is a challenge. Now, obviously the solar panel that's in my

backpack is not what you would consider bleeding edge. No, it's probably not the best that our current science has to offer. It's probably not even on the top near the top line for consumer tech right now, because what's available on the consumer side is a big drop down from the cutting edge best of the best. So, if you are getting a solar panel that has been designed to be as efficient as possible, we're talking top of

the line. This is the stuff that NASA is going to use, right, You're going to top out somewhere around forty to efficiency. And what you're talking about there is how much of the energy from the sun you're convert ing, right, So you're you're not even starting necessarily with a very high number. It's just how much of that solar energy is arriving at the panels, which is obviously going to be less than say the energy density of gasoline or

something like that, far less, far less. Yeah, so you're getting you're getting this, You're you're losing six the energy that hits the panel ra off the bat. Then that ends up being converted into electricity, and it's not that much per solar panel, Like an individual solar panel doesn't put out that much electricity, even if it's really efficient,

it's not putting out that much. That's why whenever you talk about really using solar panels effectively, you're talking about lots and lots and lots of solar panels, right, they have individual solar cells in them, and there might be thousands of these solar cells in one solar panel farm. Yeah, and if you're designing an airplane that's powered by solar panels, one of the big questions I would wonder is where

are you going to put them? I mean, when I heard about this thing before I saw an image of it, what I pictured in my mind was like a football field sized flat surface with just the tiny little, you know, person strapped to the bottom of it. And that's not that far off in a way that probably wouldn't fly. But yeah, definitely sign a plane. Yeah, you've gotta have a lot, a lot of surface area, right. You have to have a lot of surface area for multiple reasons.

So the big reasons why you need a lot of surface area, which in planes means a wide wingspan because obviously if you made the fuselage or the body of the plane the biggest part, then you have to figure out how do you get something that bulky and heavy into the air and have it have the vehicle maintain enough thrust to keep it in the air, because I mean thrust is a really important part of this too.

We we just established that solar panels aren't generating that much electricity, so they can't uh push a super powerful electric motor, and the electric motor is what's going to be turning the propellers that are going to provide the thrust necessary to get this plane in the air. So you have to keep weight in mind. You can't make it too heavy, and you still need all that service areas. So what do you do? Well, what the folks over at Solar Impulse, Oh, yeah, we should have said, that's

the one we're talking about, the solar Impulse. Solar Impulse A two is specifically what we're talking about. That there already has been a Solar Impulse one, which was kind of a proof of concept vehicle that they built in order to test out the different engineering approaches they were going to take, because their goal is to have this circle, this this solar Impulse to go all the way around

the Earth. I believe the demo of the solar Impulse one was a transcontinental flight, right It was from the West Coast to the United States to the east coast, and they had several legs of the journey. They even had set a record for the longest number the most number of flight hours consecutively for a manned solar powered aircraft.

So if you're talking about unmanned aircraft, you end up having really long times because you don't have a human that you haven't Yeah, you don't need to worry about a person saying goodbye to their family for two weeks or whatever. Uh So for the manned record, we're talking, uh twenty six hours, ten minutes and nineteen seconds, so more than a full day. And if you're thinking solar power and you're thinking, how the heck were they able to fly when there was no son, we'll get to that.

Uh but yeah, So so the records already been set. These were all proof of concepts that they were saying, well, we need to figure out what things are required for this dream of flying a solar powered aircraft all the way around the world. What's required for that to actually become a reality. So this wing span was the first thing, and the Solar Impulse two s wingspan. It's pretty impressive. We're talking about seventy two meters, uh, so that's that's

more than two and forty ft. We're talking about the uh, the width. That's greater than say a Boeing seven. But unlike a Bowing, it doesn't have a huge fuselage full of passengers and cargo. This has a tiny, tiny little compartment. Yeah, it's essentially a little The body of the plane is very small. It will allow the two the pilot and co pilot to sit side by side, just as in a traditional aircraft that's not you know, front and back like the old World War One and World War Two

aircraft were turret. Yeah, no, I'm not gonna have to worry about that. Um. But yeah, it's it's relatively small, and it's made out of carbon fiber. So carbon fiber has a couple of advantages, right, It's pretty strong and it's really light compared to other materials. So you want to use something that's going to be resilient so I can withstand the rigors of air travel, and yeah, it can't be too heavy. So carbon fiber is what they

went with. And in fact, the entire plane ends up being something like I think it's twenty six hundred, no, sorry, twenty that's around five thousand seventy pounds. That means that there are cars on the market that are heavier than this airplane. Is this airplane that has a wingspan wider than a Bowing seven. That's pretty crazy, It's pretty crazy,

you know. I would imagine one reason that they can use those kind of fibers is because this airplane goes a lot slower than your standard passenger airplane, which obviously the faster you go, the more turbulence and friction you're gonna have to withstand, right, and uh yeah, So so with a Boeing example, for example, like your average commuter airline type of thing, you're talking about speeds in the five mile per hour range. With solar impulse too, you're

not gonna go quite that fast. The top speed is something like eight per hour, eighty eight miles per hour. Fortunately, it does not require one point twenty one jiggabats for it to fly, or else it would go back. How many watts does it require? Not many at all? Really, because again, all right, do you know how many solar panels are actually on this seventeen thousand across that seventy's because I don't know how big they are. They're not. It's not that they're that big. Well, I mean, think

of a seventy two wide wingspan. Um, you know, you're that's pretty huge. It's not that the panels themselves are the solar cells. I guess I should say it's not that the solar cells are that big, because really solar cells is more accurate than panels. Panels are like a collection of cells. But they're not that big. But the fact that there're seventeen thousand of them is pretty impressive. And they're only driving four electric motors. And like I said,

those electric motors turn electric propellers. The propellers are shaped in such a way to help provide the thrust needed so that you maintain the speed to uh to stay in the air. Those wide wings also are able to provide a lot of lift and stability and flight, although it is kind of tricky. You can't take off in windy conditions with this thing. You would imagine not because with such a wide wing span, a little bit of

wind could easily get it to start tilting any which way. Yeah, you have another thing I'd also imagine is that the wider wing span allows it to stay aloft at lower speeds. Yeah, yeah, that's another thing. And it's also not going to go to the same sort of altitude that you would see with like a commuter jet or something that's not gonna go up to thirty feet. Well, I've been cruising without fuel for a while now, I think I'll just keep

on going. But uh, you you folks out there, you look like you could use a little bit of a break, So we'll be right back. Okay, So we're doing around the world flight. It's at eighty eight miles per hour. That means at top speed eight eight miles per that's

not average speed, that's top speed. That would mean there's going to be some stretches of this flight where the airplane is gonna have to stay in the air a really long time because there's no convenient way to land it at night when you're over say the Ocean, right, They're gonna be times where the you know, those oceans are so wide, there's no way the plane can make a trip across say the Atlantic, in a single day.

Not at eighty eight miles per hour. It's gonna take multiple days and nights of flying for it to get from one point to another where it can safely land. Because they do plan on taking this trip through several legs where the plane will be able to land. Maintenance screws can come out and and do some repairs if necessary, that kind of thing. It's not like it's going to do a full flight around the Earth without ever touching down. They will be touching down along the way and then

taking back off and another leg of the journey. But still when you're over the ocean, you don't have that luxury. So you've got to be able to fly at night. So that's when they switched to monkey on a stationary bicycle power. You know, I recommended that. I thought it's time has come. I mean, it's an unproven technology, I'll grant you, but I really think we have not tapped

the potential of monkey bicycles. No. I think this is they've got to be using some some pretty good batteries and that has to be a very important part of the design, right because batteries are heavy eat this airplane needs to be light. Yeah, they used uh, they created

lithium batteries. They actually had. The engineers had to look at a way to make the batteries incredibly efficient and uh, they had to be able to charge quickly because if you aren't getting a full charge throughout the day, then while you're also driving those propellers, then that could become a problem at night, right if you want to remain aloft, that could be a serious problem. So they experiment with different electrolytes um, which, of course, as we know from Idiocracy,

is the stuff that plants crave. But no, they experiment with a lot of different chemical compositions to try and make the most efficient batteries. So they went with lithium batteries. They are kind of think of like a long, thin almost like a film as opposed to a big battery pack. So it it's pretty remarkable the design, and they weigh The batteries weigh six thirty three k or about two thousand seventy seven pounds, which means that you know, the they weigh up little bit more than a quarter of

the actual plane itself the batteries alone. So obviously batteries are heavy. They're important because you have to have that energy to tap into at night, Otherwise, once the sun starts to go down or it gets too cloudy, you're

plane would plummet. And this isn't just a problem for planes, I mean it's especially a problem in planes, right, This is a problem for any electric vehicle, right, is is how to deal with this massive battery that's required to operate motors with this kind of power exactly, And it's something that we've seen not even not just in an electric vehicles, but electronics in general. We have a little bit more to say about this interesting episode, but before

we get to that, let's take another quick break. The processing power has increased steadily over the years. We've got the whole observation of Moore's law where we're seeing it practically double every two years or so, depending upon your interpretation of the observation. Uh, well, then why haven't batteries kept pace with that? You know, I'm seeing my my mobile devices getting more powerful, but the batteries draining faster,

so it's not as useful to me as long. And part of that is just because batteries aren't on that accelerated path. I mean, there's only so much we can do with chemistry. To be fair, they have come a long way. This is also a topic we talked about not too long ago on Forward Thinking, is how far batteries have come. And it is kind of amazing what we've achieved today. I mean, your standard lithium ion battery today is kind of a wonder work, it really is. Yeah.

The fact that you're able to recharge it so that the chemical the electrochemical reaction that's going on within the battery gives off electrons. I mean, that's the whole point of a battery. Otherwise it would be useless. Uh. And in a in an alkaline battery, this is an irreversible uh reaction, So the electrochemical reaction happens, electrons are given off. As a result, you can use those electrons to do work,

thus electricity. But once it's drained, once that chemical reaction has gone to a certain point, you're not generating enough electrons for it to be useful anymore. You have a dead battery. Whereas with these lithium rechargeable batteries. There are non rechargeable types too, but with rechargeable batteries you can reverse that reaction by essentially forcing electrons back backward through

that pathway. It's basically doing the whole thing backward. You're putting work into the battery the same way you took work out of it earlier. Yeah, So the fact that we've managed to do that and increase the efficiency even a little bit. Is the reason why something like the

solar Impulse too is is possible. And again we're not going to see this actually fly around the world until two thousand fifteen, but they've already proven that it works with that first proof of concept vehicle that was able to stay up in the air for twenty six hours. The fact that it was able to charge the batteries, fly all the way through the night and continue, Um, you know they're fully certified to fly at night. It shows that there's been a lot of work done here.

So we've got, uh, the energy side covered. The fact that it's going to be using solar power to drive the electric motors and day switched to battery at night. It's going to be able to fly really for as long as the pilot and co pid can stand. That was my question. Yeah, what's this gonna be like for the pilot incopilot? Okay, have you ever, Joe, have you ever traveled first class? Oh? No, okay, so I've traveled

first class. Not to brag, but it's prett sweet. And once you traveled first class, how is the champagne and cheese select? We didn't have champagne. We had real pain, thank you, none of this champagne you guys talk about. Um no, but but I mean it's anyone who's traveled first or business class and then goes back to travel coach, the belly aching is unbearable, right, It's just this idea. Oh no, yeah, you can't go back, by the way.

I haven't traveled first or business in years, and and frankly, I'm still amazed that planes work, so I'm happy either way. But but there was a period shortly after that time where I was able to travel first or business where I was one of those unbearable people for that particular reason. I'm unbearable for many other reasons now, but for that

particular reason where I can't believe this wonderful complaining. I know, flying coach, though, would seem like an amazing luxury compared to what the pilot and co pilot are going to have to be able to endure to make this round the world flight a possibility, because one of the things they're gonna have to, like I said, stay in the air for some of the estimates are as long as five days and nights, or perhaps even longer for just

one leg of this journey. So for five days and nights, you are in a chair in a plane and you cannot go anywhere because there's no space. Every single ounce matters on that plane, every single inch counts, so there's no space in the back for one person to go and and collapse while the other one flies the plane. Instead, their chairs are going to be designed in such a way where they can lay back into a cot form

and you can. The plane is going to have an autopilot, so they can sit there there heading and course and both catch them z s while they need to, and then wake up and everything should be fine. Um somehow I don't suspect that will happen. Well, I think it's probably more likely that they're going to do their best to take shifts. But the nice thing is that they can set on autopilot and catch some rest if they

need to. But alright, so we've got we've got laying down to rest, and we've got sitting up to operate. But there's still one important human activity besides the whole eating and drinking thing. They'll obviously have some food and water up there on the plane as well. There's one other important activity that we can't avoid. Yeah, I was about to ask have the engineers factored into the plane's course the fact that it might be losing a bit of mass as it travels. So what we're alluding to

is where do you poop? I mean, you know, it's one of the most popular questions on how stuff works, as main site is all about space toilets um. In this case, those fancy chairs I was talking about they double up as as both chairs and cots. Well, really they do triple duty because they're also lavatories. I had to do it. Joe. Joe is rolling his eyes, So everybody,

we've already achieved some horrible pun hat trick. Everybody who misses Lauren's eye rolling, just that her spirit is living in Joe right now, even though Lauren herself is not in thet Yeah. So um, but no, it's it's true. The the actual chairs are going to do this this triple job of being the place where you sit, the place where you sleep, in the place where you have to go to the bathroom because they couldn't incorporate a separate lavatory because again, every single bit of weight counts.

It seems like there would be ventilation shues. Yeah, I haven't. I haven't actually seen any illustrations or animations of how this actually works, Like, does does the does a little bit of the bottom of the chair just open up to the to the I mean, who knows? I honestly do not know the answer to that, because I haven't seen the illustrations I've seen. I've seen footage of them testing out the chairs, laying it back into cot form, but not the pooping. Well, here's a question I don't

know if you know the answer to. Is the cabin pressurized? Are they flying at such an altitude that they don't have to press size the cabin? And now the pictures I've seen, I've seen them wearing essentially air masks as well, so I would imagine that the cabin is not pressurized. But I also imagine they're not typically flying in an

altitude where that's too much of a problem. They did, as I saw, have have masks there because I saw a guy who essentially he pulls the mask aside in order to eat a little snack cake, drink a little water, put the mask back on, go on his merry way. Um, But whether or not the whole thing is pressurized, I don't think it is because again, that would require a lot of weight to be able to put in the

systems necessary. You have to seal everything off, obviously, because if if you don't seal everything off, you can't maintain a pressure, and you know, it would just be escaping the whole time. Plus then you would have to have the mechanisms necessary to pressurize the cabin, and all of that adds weight. So really, when it comes to solar aircraft in general, not just the Solar Impulse, but any solar aircraft, anything that's not absolutely necessary to maintain flight

tends to be left behind. So you don't have a lot of the systems and a lot of the other niceties. In fact, a lot of solar aircraft don't even have landing gear. They have they have wheels that allow them to roll around when they're before they take off. Then once they take off they jettison the wheels because that's weight,

like the fuel containers on the Space shuttle. Yeah, so it means that when you're landing, you're not so much landing as you are having as controlled to crash as you possibly can, which I'm sure is nerve racking, but that's part of the design. So the plane is designed to have that kind of landing. It's not, you know, an emergency type thing. This is this is standard operating

procedure onboard solar aircraft. And uh yeah, so, I mean it's kind of I'm curious to see really how this continues to develop, what the experience ends up really being like for the pilot and co pilot, what it you know, whether or not they're able to make this. By the way, I didn't mention this their plan for the entire journey. You know, we're talking about that eight eight miles per

hour top speed. It's going to take them five months to go all the way around the world, and that's in various legs of the journey, so it's going to be lots of stopping and starting, but five months total. So it's uh, you know, it's it's it's not something that's going to take place super fast, obviously, but I'm really curious to see if they're able to make it all the way around the world. And one of the things I love about this is that it's and it's

really a pure engineering challenge, right. The whole thing was this idea of let's build a heavier than air aircraft only powered by solar energy. Um, the batteries are charged by solar energy. So that's how you can say that it's only powered by solar energy and be able to fly it all the way around the world. All right, that's our goal. How do we achieve that? And on

a sleep. When they first started thinking about this, they started talking about it back in when they first started thinking about it, it was not something that could have been achieved just based upon the technology they had at their disposal. The team had to innovate and and invent things and tweak stuff in order for this to happen.

And that's what I find so exciting because it's one of those projects where even if you think it's a ridiculous endeavor to fly around the world in a solar powered aircraft, the truth is the work that they're doing can inform other industries and other technologies that end up

benefiting us in the long run. Yeah. Well, before I read about this particular story, I would have thought a solar powered aircraft was just impossible, that there's no way you can generate enough power to create the thrust you need to stay aloft and heavier than air aircraft. Obviously, if you have a balloon or something. But right, yeah, and so it just blows my mind that they can

do this at all. Not to mention the the extent to which there take king this technology, we should talk about how this is almost certainly not going to be the passenger plane of the future because all of the First of all, I think all the reasons that we gave of what they had to do in order to make this possible. I'm pretty sure that your average frequent flyer doesn't want to poop in their chair, right, that would be a big one. Well, and you can't get

enough people on it, it doesn't go fast enough. You can't pressurize it, or at least that's what I assume. I could be wrong about that. I didn't see anything about pressurization on about the solar impulse. If I'm wrong about that, that's fascinating. I would want to read more about that. How they achieve that using this lightweight approach. But well, even if you table that one, I mean, all the other concerns make this this is not going

to replace the passenger jet. No, No, they What it could do is you could take a look at all the different considerations the tea made in order to make the aircraft as efficient as it possibly can, and some of those lessons you might be able to apply to

aircraft designed in the future. Yeah, And I would think one thing to focus on, or at least for us to remember, is that the advances that come with this kind of aircraft that are really important to future aircraft that people might fly in are not necessarily like the

solar panels or the solar implementation. It might be the ways that aircraft like this use clever tricks to become lighter and still stay have enough stability in the in the fuselage not to come apart, right right, Yeah, because one of the things, you know, one of the big reasons why this is so important is that we didn't really address this, but air travel generates a lot of pollution.

Right Your standard your standard jet, like your standard commercial jet, can create as much as point forward to point six five pounds of greenhouse gas per mile travel. That all depends on the destination and paradoxically, perhaps uh, the further you go, the less you're generating per mile. But the reason for that is because takeoff and landing are where you generate the most greenhouse gases because they require the

most power. Yeah, there are people who talk about buying carbon offset credits when you take an air travel journey. That's not a bad idea, even though through through air travel it's not necessarily just carbon emissions. Is other greenhouse gas more prevalent in jet fuel exhaust? Ye, But I mean it's it's a huge amount. Like you're talking, you know, point forward two point six five pounds of greenhouse gases.

I mean, I don't know if you've weighed a gas recently, but it takes a lot for it to make a pound, So you're talking about a truly massive amount of greenhouse gases every time an aircraft is flying. Uh. And again, depending on the type of aircraft and how far it's going, that's what tells you how much average you are generating.

So if we're able to take lessons from things like the solar impulse to air craft and incorporate them into future aircraft design so that aircraft are more efficient and using less fuel than we are, having a smaller negative impact on the environment overall. Yeah, And while as we said, there's probably not going to be a solely solar powered aircraft,

there may be hybrid aircraft in the future. For standard commuters, and you know, you can see the possibility of using solar power for things other than the thrust, right, you can use solar panels to do things like help power some of the various systems aboard the aircraft, depending upon

what kind of aircraft it is. I mean, you probably don't want all the avionics powered by solar power, but things like cabin lighting that kind of stuff could certainly be augmented through solar power either probably in a more uh analogous way to the way the solar impulse has batteries.

You would probably use the solar power to charge batteries and then the systems withdraw electricity from the batteries not have a direct line solar panel to system because that wouldn't be as useful in in you know, all the different situations that aircraft go in. The Other thing about to keep in mind is the aircraft tend to fly higher than your your regular cloud level commercial aircraft do, so they actually have better access to sunlight than say

something that can't go that high. Um. Yeah, and also we're seeing this technology being incorporated into unmanned aerial vehicles. Uh, there's already proposals for u A v s that could use solar panels and never have to land. They could just stay in the air perpelled, you know, until they needed some form of maintenance. So until something breaks, they're fine,

in which case they'd probably just crash. Yeah, if there's enough of a warning where you know something's going to end up, or you just have you know, a set schedule or when things need to have regular maintenance, then you might be fine. But if you get a note saying, oh, propeller failed, and probably like, well lost that one. But it's in interesting because it could be used for all sorts of stuff, not just I mean a lot of people sit there and think of surveillance, but that's not

the only use. You can use it for things like sending it into a dangerous area that's been hit by a disaster or other sort of calamity and get a really good idea of what's going on before you send any kind of first responders in, or in a example like the Fukushima nuclear reactor disaster, you want to be able to send in you know, robots and that kind of stuff without having to put people in harm's way,

because that's that's potentially a really dangerous situation. And having something that can maintain its position for a longer amount of time is more useful than something that just gets a snapshot and then that's all. You know. The battery life is only twenty minutes or forty minutes and then you have to fly it back. Uh, that's not as useful. Having something that can maintain its presence and keep an

eye on developing situations is incredibly useful. So I think we're going to see that kind of technology more widely deployed over time as well. So I'm really really excited by this project. I mean, I love any kind of engineering challenge where it makes people think creatively about how

to solve these problems. So maybe in the future will do an episode about some of the amazing DARPA challenges to like some of the ones that have incredibly difficult tasks that engineering teams have to figure out how do they achieve these these goals. I like the problems that are specifically like this, where you're trying to squeeze every

last drop of efficiency out of a mechanical system. Like the same way I might not admire the way they drive in terms of safety reasons, but I like reading about the hyper milers, the people who try to get every possible efficiency advantage they can out of their car. Well, Joe in an in an offline conversation that we had earlier this week, we've already determined that Mrs Todd shortcut

isn't interesting. King short story about you know, finding that most efficient, most efficient route, even if it costs you your sanity. Um, yeah, but no, I agree. I mean it's one of those things where you always think, like, there are those moments where you think, all right, we've hit it, We've hit the pinnacle. There is no squeezing a single ounce of efficiency more out of this. Somebody smart can probably figure something out. Yeah, which is that's

always fantastic. I mean because again, we all stand to benefit. It might not be immediate. It might not be that the next day you wake up and suddenly the world is a magical place. But it could mean that another five or ten years down the road, technology that we had not thought was possible is a mundane reality because of the things we learned from these engineering challenges. It's pretty cool. So yeah, I think first I want to say thank you Joe for coming on the podcast visiting

te stuff. Hell, well, you know, the hounters are all ours, And that wraps up this classic episode of tech Stuff. Hope you enjoy aid listening to it. If you have any suggestions for future topics I should cover, or any topics that require an update or three, let me know. You can reach out on Twitter the handle we uses tech stuff h s W and I'll talk to you again really soon. Yeah. Text Stuff is an I Heart

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