back to article Giant solar-powered aircraft takes to the skies

Swiss adventurer Bertrand Piccard today moved one step closer to fulfilling his ambition to fly a solar-powered aircraft round the world as his Solar Impulse completed its first full-fat test flight. The Solar Impulse The Solar Impulse boasts a wingspan as wide as a Boeing 747, with 12,000 solar cells powering four electric …


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  1. Locky

    Probably best

    To avoid clouds

    1. Nigel 11

      Avoid clouds

      Don't know what it's cruising altitude will be, but 10,000 feet puts you above most of the thick stuff over low-altitude land, and light high overcast still lets plenty of light through for solar cells (which are happy with diffuse illumination).

      10,000 feet is also low enough that one can breathe comfortably without pressurisation.

  2. Graham Bartlett
    Jobs Halo

    Can I be the first to say

    "Make it so, Number One. Engage!"

    (Ballmer icon is the closest thing to Jean-Luc.)

    1. M Gale

      Earl Grey, Hot!

      See title.

    2. Goat Jam

      That icon is

      St Jobs of Cupertino.

      1. M Gale

        Re: That icon is..

        ..just goes to show. Can't really tell any difference between them these days.

        Mine's the asbestos-lined one over there.

  3. John Robson Silver badge

    5 hops != flying round the world

    Or I can jump 7 miles...

    1. Gene Cash Silver badge

      What kind of stupid crap is that?

      Flying around the world is flying around the world, no matter how many stops you make. Are you saying I didn't fly from Florida to Arizona because Delta made a connecting stop in Colorado?

  4. Jimmy Floyd

    Burning up in the light of the moon

    "...five days continual flight per hop..."

    I'm presuming it has batteries for night-flights? Or perhaps the moonbeams are particularly strong in certain parts of the world.

    1. Natalie Gritpants Silver badge

      Flying where there is no night

      Maybe they're planning on flying inside the Arctic circle in the summer. Would that count?

      1. M Gale

        Remind me..

        ..of some old program with David Bellamy. He took a trip to the North Pole. Stuck his brolly in the floor on the pole, and walked around it. "There, I've just walked around the world!" ...and backward.. "And again!"

        Love that guy and his distinctive accent.

  5. Boris H.


    Going where no man has gone before.. umm wait wrong Piccard

  6. OffBeatMammal

    wonder what they'll charge

    for lugguage...

    1. Robert E A Harvey


      I'dhave thought anything that brought a charge would be welcome

  7. Will Godfrey Silver badge
    Thumb Up

    Good luck to them

    That's what I say, never mind you cynical bar stewards. I think it's great that people are still trying something different and not just following the herd.

    1. Anonymous Coward
      Thumb Up


      fantastic, even using hops this is one hell of a challenge. Agree with Will, stop whinging, this beats sitting at home watching Discovery.

    2. M Gale

      Obligatory ipad joke.

      Insert here.

  8. mahonj

    What is the point of this vehicle?

    I don't get the point of it - if it is for a persistent surveillance platform, it will need to be faster to be able to maintain position against winds > 50 mph, which you certainly get at 30K feet.

    So it would be unmanned - no problem, but if it can't maintain position, it won't be much use, unless you had a series of them being blown around on the trade winds, and using their power for data transmission.

    1. James Hughes 1


      The point? To fly around the world using solar power only.

      I thought that was covered in the article.

    2. No, I will not fix your computer

      Re: What is the point of this vehicle?

      The clue is in the article;

      The €70m Solar Impulse project is designed "to contribute in the world of exploration and innovation to the cause of renewable energies" and "to place dream and emotion at the heart of scientific adventure".

    3. Anonymous Coward
      Anonymous Coward


      If we followed this line of thinking the Wright Brothers would never have taken off...

    4. M Gale

      The point.. probably "to show we can". Think of it as being a more modern Wright Flyer. Totally useless in a practical sense, but demonstrated some very important concepts.

    5. Fred Bauer 1

      The point is

      the same as climbing Everest, or flying solo across the Atlantic, or flying a balloon around the world, or...

  9. Poor Coco
    Paris Hilton

    How does it land?

    It looks like the fuselage rests on a dolly for takeoff. How does it touch down without destroying the tail?

    1. JimND

      The title is required, and must contain letters and/or digits.

      There's a wheel at the base of the tail, two very long retractable wheels on the wings and a retractable nose-wheel. The 'dolly' looks to be access steps for the pilot, and probably some maintenance/monitoring stuff.

      Looks good fun though. I'd love a go in it :)

  10. Trevor 10


    Assuming the 44mph figure was a ground speed, and assuming that they stuck to the equator which is 24000 miles (of course it wont be with the equator, they will want to be over land as much as possible so flight distance would be longer)

    I make that a little short of an 18 month journey, but the article seems to be saying the journey will be less than a month (5 day legs x 5 legs).

    Are they traversing the global just a little south of the north pole and hence covering 360 degrees but only actually flying 500 miles?

    1. Anonymous Coward

      Get a calculator

      44mph x 24hours x 5days x 5hops = 26400miles

    2. JaffaMan

      check your sums!

      Very quick maths check only accounting for ground distance covered around the equator, no stops, constant speed etc.

      24,000m/44mph = 545.5 hours non-stop flying time

      /24 = 22.7 days or just over three weeks.

      So yes, it would be just less than a month if you include a few stops.

    3. Anonymous Coward


      Not entirely sure how you came to this figure, missed a multiplication somewhere or something?

      The equator's about 25,000 miles..

      At 44mph average speed, theyll complete an average of 1,056 miles per day (44 x 24 = 1056)

      Theyre planning on upto 5 legs of 5 days each, a total of 25 flying days. 1056 x 25 = 26,400 miles they can potentially cover in this 25 days at an average of 44mph.

    4. Ammaross Danan


      24000 miles / 44mph = 545.45~ hours / 24 (hours in a day) = 22.72~ days / 5 ("legs") = 4.54~ days per leg.

      Math works out fine for a 5 day leg x 5 legs.

    5. Fred Bauer 1

      Check your math

      Flying continuously, they'd do it in 23 days. You are thinking they are only going 44 miles per day!

    6. Stuart 18

      44mpH that's Miles Per HOUR

      Recent reckonings give us approximately 24 of them hour thingies every day so that's 24 x 44 = 1056miles per day x 5 = 5280miles per leg x 5 = 26,400 miles comfortably making a trip around the world with maximal landfall (sic) I surmise the previous poster was using 44miles per DAY to get 18 months.

    7. Simon R. Bone

      @Trevor 10

      er..... there are 24 hours in a DAY -> 44miles*24 = 1056milers per day -> 23ish days of flying

    8. Trevor 10


      immediately after pushing the submit button for my previous post I realized, I was out by a factor of 24.

      no prizes for guessing what I forgot to do in my calculations

    9. MadChemist

      confused indeed

      ...your confusion probably arises from the fact that your days seem 23 hours shorter than the average for this planet.

      "mph" after all does not stand for "miles per day" and thus, with your numbers the whole trip would take 22.7 days airborne.

      1. Tom 7 Silver badge

        That is assuming your we're stupid enough

        to insist on still air to fly in. Using trade winds would more than halve that.

        1. M Gale

          Trade winds?

          Not unless it's a flying galleon. If they could get high enough to take a ride on the jetstream however, ~300mph would certainly help. Of course that would mean taking oxygen on board, and I've a feeling every ounce matters on an aeroplane like that.

          Pirates because, well..

  11. Stone Fox

    it looks a little small to have a toilet...

    "up to five days continual flight per hop"


    I'm guessing that at the heights they'll be flying the windchill factor of sticking your arse out the window to do your business might be a little extreme.

    1. M Gale

      Mummy, there's an aeroplane up in the sky..


      Goodbye blue skies, indeed.

  12. Filippo Silver badge

    solar powered

    If only it flew faster (okay, a lot faster), it could simply follow the sun around the globe.

  13. Adam Williamson 1


    It's a proof-of-concept, you numpty.

  14. Anonymous Coward

    How will they take a shit?

    Just asking?

    1. lglethal Silver badge

      Astronaut diaper perhaps?

      I do not want to be the one meeting them at landing time, i have to say!

  15. John Smith 19 Gold badge

    Roughly 22 days 18hrs continuos flight

    Challenging to say the least.

  16. Martin Usher
    Thumb Up

    A little thermal help please!

    If this beast is a sailplane with additional electric power then it could conceivably stay up for a very long time, especially if it got some altitude. Sailplanes can travel quite fast -- at least as fast as a light plane -- and in the right conditions can stay up all day (or until the pilot gets bored) and attain serious altitude (20,000feet+).

    The whole purpose to staying up is to end up with an unmanned plane you can send up and tell to loiter for the next month or two. Its cheaper than launching satellites. (As for any human needs -- find out how glider pilots cope.....)

  17. A 15
    Paris Hilton

    I know how Trevor10 got to the figure...

    He did 44 miles per day instead of 44mph. It comes to about 1.5 years then.

  18. Bounty


    "Flying around the world is flying around the world, no matter how many stops you make. Are you saying I didn't fly from Florida to Arizona because Delta made a connecting stop in Colorado?"

    Correct, you flew from Florida to Colorado, then from Colorado to Arizona, not from Florida to Arizona. It probably doesn't make a big difference when going on vacation, but when you're trying to brag about your awsomeness it does make a difference. What this guy is doing is hard, but I'll be even more impressed by the guy who does it nonstop.

    -Bounty "I've gone 10,000 hours without eating" (just not consecutively) Hunter

    1. Penguin007


      You are a sanctimonious prick. Why don't YOU build a plane that flies around the world without stopping?


  19. CAFE Foundation
    Thumb Up


    This achievement is about the extreme technical challenges in aero and energy use. A noble effort and one that will surely have spin-off benefits.

    1. Nigel 11
      Thumb Up

      Spin-off benefits

      Definitely. Replace the human pilot with a robot and a bunch of comms gear, get the endurance up from days to months, and you have a cheap and quasi-stationary replacement for satellites to bring 21st-century communications to rural areas. (They'd need to increase the cruising altitude, but with no human pilot that might not be too hard).

      Actually, better than satellites, for which speed-of-light latency is a nuisance or worse.

      You might care to ponder how many "essentials" of a modern car were invented and developed for racing or rallying, and might never have been developed at all if motor-sports had not been pushing at the envelope.

      1. mahonj

        The problem is holding position, not endurance

        It seems obvious that this is a test for a long endurance UAV where they put in a pilot during the test phase as they need the flexibility that a pilot gives during development.

        This I buy.

        However, I am not sure it will be able to remain circling around one point for a long time if the wind gets up. If you can only go 44mph, and the wind is > 44mph, you will start to drift off.

        What they need is more power, and hence solar cells that are more efficient for the same mass (check out their website). They would also like better batteries (as would the whole EV world).

        They may be in luck with the batteries as loads of people are working on this, it is likely to happen sooner or later. The solar cells are another matter. Lots of people are working on solar cells, but I have not heard of anyone working on very LIGHT ones. This they will have to pioneer themselves.

        Then there is the ultimate efficiency of solar cells. These seem to top out at about 38% at present for very expensive ones. They are using 12% ones (for lightness), and we could imagine they could get to say 18% with a little work.

        This is still only 50% more power, which might allow them fly 25% faster - say 55mph - this is still too slow to hold position in many stratospheric zones.

        1. Nigel 11

          Better than 18%

          You can buy 18%-effficient panels to go on your roof today. The gap between best and cheapest will narrow for solar cells, just as it has for CPUs.

          For light weight, one wants a thin film solar panel, rather than thick(ish) slices of silicon assembled into an array. Then integrate the thin film into the flight surfaces of the UAV. You can probably do that with CdTe or CIGS, and the technology of thin-film solar cells is rapidly advancing.

          It might not be the end of the world if one could not do stratospheric position-holding, though it would require some diplomatic effort to allow a large number of high-altitude unmanned communications platforms to "orbit" the planet in the stratosphere. Manouvering ability sufficient to avoid being blown over a few paranoid states like North Korea might suffice, if China, Russia, the major emerging economies and the West agreed to allow a worldwide UAV communications system.

          Air is much thinner at high altitude - doesn't that reduce the amount of power needed to fight a headwind?

  20. Louis 3

    Flight, right!

    This is all well and good... in theory. But, everyone knows that you can't "fly" around the world!

  21. SolarDude

    Better alternatives

    While this is cool, to me this seems much less promising than other technologies. Consider this:

    They also have a flying prototype. And their craft is faster, flies higher, is safer, wouldn't be affected by cloud cover, and most importantly can actually carry a useful load. I think the future of solar powered aircraft is more likely to take a shape like this than a heavy aircraft that can not lift anything.

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