Solar Impulse 2 Plane Takes Off From Egypt On Final Leg Of World Tour (reuters.com)

How long would it take an airplane to fly around the world without using any fuel? About 22 days of actual air time, according to Fusion. Solar Impulse 2, an aircraft which is powered by solar energy, left Egypt on Sunday on the last leg of the first ever-fuel free flight around the world. The team behind it tweeted a few minutes ago that they have completed 91% of the final, last, conclusive flight. Reuters reports: Solar Impulse 2, a spindly single-seat plane, took off from Cairo in darkness en route to Abu Dhabi, its final destination, with a flight expected to take between 48 and 72 hours. The plane, which began its journey in Abu Dhabi in March 2015, has been piloted in turns by Swiss aviators Andre Borschberg and Bertrand Piccard in a campaign to build support for clean energy technologies. "The round the world flight ends in Abu Dhabi, but not the project," Piccard told Reuters a few days before takeoff. Solar Impulse flies without a drop of fuel, its four engines powered solely by energy collected from more than 17,000 solar cells in its wings. It relies on solar energy collected during the day and stored in batteries for electrical energy to fly at night. The carbon fiber plane, with a wingspan exceeding that of a Boeing 747 and the weight of a family car can climb to about 8,500 meters (28,000 feet) and cruise at 55-100 kph (34-62 mph).

Comments

22 Days?

[Anonymous Coward]

Starting in March of 2015 to now isn't 22 days. It may have only been in the air for 22 days, but the trip sounds like it took about 1 and a third years.

Re:22 Days?

[Anonymous Coward]

Your advertising career is now over...

Re:22 Days?

[Archangel Michael]

22 days? My ass. It has been on the ground longer than in the air, which is probably some sort of record itself. And this is hardly news worthy except for the fact that it proved only one thing, that solar airplanes are highly impractical. No, it didn't prove that it could be done. Moving a mountain one grain of sand at at time isn't really proving you can move a mountain.

Re:22 Days?

[tnk1]

Yeah, the way most of these flights go, they end up on the ground longer for getting permissions to fly through airspace, fixing the plane, trying to get more money, and for other random stuff than they actually spend flying.

While you don't need fuel, there's no way you can guarantee that a plane that slow, fragile, and with limited cargo space can remain aloft for long periods of time with human passengers. There is a lot of groundwork, so to speak, to keeping a flight going.

What would be really impressive is if they have been able to actually fly the plane with only short, necessary stops to load food/water and perhaps do some maintenance checking. There would probably be an occasional need to wait for weather on take off. That still wouldn't be 22 days, but I'm sure it could be done in less than 80.

I just wish there was somewhere to go with planes like this. Unless they seriously reduce battery weight, you're never going to do more than some well financed adventuring in a solar plane.

Re:22 Days?

[PCM2]

Moving a mountain one grain of sand at at time isn't really proving you can move a mountain.

It isn't? I mean ... that wouldn't impress you? WTF would?

Re:22 Days?

[jellomizer]

Like a lot of people you miss the point. Sometimes the invention isn't meant to be mass produced but more of a proof that it can be done. Having it travel the world was a publicity stunt. But it was a stunt to show the advancements in solar energy. Not to spur a world of solar heavier than air aircraft. However the real progress is in using technology to build an aircraft light enough, and with enough power generation to support a long term flight.

Now if we take the stuff that we learned, use these solar panels on our homes, use the construction to make more fuel efficient planes. Even just keep the knowledge around until solar panels get more efficient or batteries get lighter to make such a device more useful.
However to pull such a stunt safely shows progress.

Re:22 Days?

[Archangel Michael]

This guy ...

https://en.wikipedia.org/wiki/...

Which is WAY more impressive than sitting on the ground for all but 22 days and calling it a record. ;)

Re:22 Days?

[Archangel Michael]

How much time would it take to "prove" it could be done? 365 years? Fly 100 Meters, land, charge for a month, do it again. That doesn't prove ANYTHING, except patience. It wasn't hard to fly 22 days, if they flew 22 days in a month, I would suggest that would be something. Flying 22 days in 44 days would be important. Flying 22 days in 90 days, 180, or even 270 days would be significant, but they have taken well over 1 year to complete the task, flying only 22 days out of that period. Meaning, they took over a year on the ground to fly 22 days. Not all that spectacular. And it only proved one thing, it is currently VERY impractical.

Re:22 Days?

[Solandri]

Unless they were covering up the solar panels while on the ground, and only using them to charge batteries while in the air, there is no point.

Technically all energy sources except geothermal are solar. Fossil fuels are solar energy collected by plants millions of years ago. Wood is solar energy collected by plants in the last few decades. Nuclear is energy from stars which went supernova to create the elements heavier than iron that we use for fission. Wind is the air's movement in reaction to differences in localized warming by the sun. Hydro is water which was evaporated by the sun, and traveled to a higher potential energy state.

So if you're charging your batteries with solar panels while the plane is sitting on the ground, then it's really no different from using any of the above energy sources. It's all just collecting solar energy in one time period, and using it to fly a plane around the world in a different time period. They're just doing it with solar panels (collector) and batteries (storage), instead of with plants (collector) and oil (storage).

The only way this would be a technology demonstrator is if they're only using the solar panels to charge the batteries while in the air. That would be demonstrating that a plane can carry enough solar panels to sustain itself in continuous flight through both day and night. I've been following this project on and off since it first began with their first plane, and I still haven't figured out if this is what they're actually doing. It's like they want to do it because Solar! Not because it would indicate we've crossed a fundamental engineering threshold with PV technology (generating capacity / weight has exceeded a certain point which makes continuous flight possible).

No fuel?

[110010001000]

No fuel? How does it fly with no fuel??? Magic rays?

Re:In other words significantly worse than a hot a

[110010001000]

But they are out to "build support for clean energy technologies", just like the Volvo Ocean race is to "build support for the ocean". It isn't just a bunch of rich guys avoiding real work. We promise.

So whats the Southern Hemisphere? Chopped liver?

[OzPeter]

Is there any reason that this plane couldn't have flown into the southern hemisphere for part of its flight? It's not like we don't have sunlight down south.

Re:In other words significantly worse than a hot a

[jellomizer]

Chuck Yeager's Bell X-1 That broke the sound barrier. Wasn't useful for fighting or carrying cargo. All it did was go faster than sound.

Still 70 years later we only break the sound barrier on a limited bases. As its cost and safety are still large concerns.

Now lets say you take this solar technology and make solar power blimps, and we move to slow and steady transportation future.

Re:So whats the Southern Hemisphere? Chopped liver

[XXongo]

Is there any reason that this plane couldn't have flown into the southern hemisphere for part of its flight? It's not like we don't have sunlight down south.

Hm-- if it never crossed south of the equator, it didn't really fly around the world, since it flew a route considerably shorter than a great circle.

I mean, if you go to Antarctica and walk in a circle of radius one meter around the south pole, you didn't really circumnavigate the globe on foot.

Re:1 seat 2 pilots

[Maxwell]

Pilot A lands the plane. Pilot B, having flown ahead on a commercial airliner, and is thus well rested, gets into the plane and takes off. Claim to be green. Repeat.

Re:1 seat 2 pilots

[I4ko]

So in other words you are saying while pilot A was flying the plane, pilot B was stored in a place where sun doesn't shine ... I mean inside an aluminum cylinder.

Re:In other words significantly worse than a hot a

[unrtst]

Chuck Yeager's Bell X-1 That broke the sound barrier. Wasn't useful for fighting or carrying cargo. All it did was go faster than sound.

Still 70 years later we only break the sound barrier on a limited bases. As its cost and safety are still large concerns.

Uhhh... is your point that, 70 years from now, we will only use solar for flight on a limited basis because the cost to performance and weight ratio still sucks?

I think it's a neat achievement, but to attempt to tout that it is ecological or uses zero fuel is BS. The support crew still needs to travel from place to place on each landing point it made, effectively burning up way more fuel that it would take for one or two pilots to fly around the world using conventional aircraft. When it can do it all on its own, and hopefully non-stop, that will be a huge feat. Feel free to go unmanned for that - having a person on board shouldn't make much difference these days.

Piccard

[hypethetica]

This family has a long history of aviation firsts, and I assume the pilot here is a grandson of this guy: https://en.wikipedia.org/wiki/Auguste_Piccard/ And yes, that's the same sirname which inspired Gene Roddenberry to create Jean-Luc.

Re:So whats the Southern Hemisphere? Chopped liver

[mandark1967]

M8 if it flew down under the equator the solar collectors would be on the wrong side of the wings ;)

Wind energy still better

[johannesg]

I mean, wind-powered ships have been doing this for over half a millennium now. Clearly solar has a lot of catching up to do.

And how many continents were discovered using solar power so far? I tell you, wind is where it's at!

Re:Wind energy still better

[angel'o'sphere]

Perhaps you should a few "half a milleniums"?

Sailing rafts we know since about 4500 before christ. Boats minimum 3500 BC, likely even older.

Sailing over the Oceans, e.g. Atlantic did Eric the Red around 1000. The Polynesians settled the Pacific since 4000 BC ... with sailing boats and rowing canoes.

Re:So whats the Southern Hemisphere? Chopped liver

[angel'o'sphere]

That is actually not as "un funny" as it seems.

When the F16 was in the conception phase, they had the idea to disallow certain flight maneuvers. E.g. flying on the back etc. So they had a strict computer trying to interpret the pilots steering commands and keeping the plane in the air and follow that command as close as "reasonable".

Unfortunately they had sign error when calculating the normal vector of the planes orientation on the southern hemisphere.

Result: if you cross the equator the plane thinks you are flying upside down. According to "the rules" that was not allowed and you where flipped around. Then again: the pilot realized the plane is really flying upside down and tried to flip it around: but he could not, as the flight computer was exactly preventing that!

Interestingly this bug was found in the Simulators, before the plane even was flight ready. The idea of so much computer control as abandoned then.

Much more impressive flight in 1929

[fnj]

The Graf Zeppelin flew around the world in 4 hops in 1929, racking up a total flying time of 12d12h13m and a total elapsed start-to-finish time of 21d5h31m. The longest leg was Friedrichshafen, Germany to Kasumigaura, Japan; 11,743 km in 101h49m. The Pacific leg was 9634 km in 79h54m.

This was less than a year after completing the zeppelin, which was the first intercontinental commercial airship in the world. There were no breakdowns during the entire operation, and no unexpected stops or layovers. There was a full load of paying passengers and commemorative mail. Passengers slept comfortably in cabins, ate meals in a dining room, and viewed the spectacular scenery through large windows (which could be opened) from an altitude of only around 300 meters.

Contrast that with a cluster foxtrot lasting 2 years, taking 17 hops, and a total of 22 days flying time.

Re:The Wright brothers would have loved you!

[knorthern knight]

> This is huge news - this is first aerial circumnavigation of the globe that hasn't involved fossil fuels.

B U L L S H I T
http://gizmodo.com/flying-a-so...

* There's a 28-person Mission Control Centre in Monaco (60 people to provide round-the-clock coverage)

* It needs a Russian Ilyushin IL-76 strategic airlifter, a four-engine jet originally designed to carry machinery and military supplies into remote parts of the USSR. Yes, a fossil-fuel-burning 4-engine jet.

* The Ilyushin IL-76 carries a ground crew. You see, the Solar Impulse needs people on the runway to grab its wings when it lands. This results in shutting down a regular airport for 20 minutes, and regular passenger flights being delayed for these special snowflakes.

* Oh yeah, the wingspan is so honking big that it won't fit in a regular hangar. And it's rather fragile, so you don't want it sitting out in the open. So the Ilyushin IL-76 also carries around an inflatable hangar.

* The plane *MUST AVOID CLOUDS*. That includes cirrus overcast above it, because then its solar cells don't work.

In short, it's an expensive publicity stunt. And since they needed an Ilyushin IL-76 jet to circumnavigate the globe with them, I repeat... the bit about "fossil fuel free" is absolute bullshit.