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Transportation

Solar Impulse Plane Begins Epic Global Flight 65

Posted by samzenpus from the as-far-as-the-sun-will-take-us dept.
An anonymous reader sends word that the Solar Impulse 2 airplane has begun its attempt to fly round-the-world powered by nothing but the sun. "A record-breaking attempt to fly around the world in a solar-powered plane has got under way from Abu Dhabi. The aircraft — called Solar Impulse-2 — took off from the Emirate, heading east to Muscat in Oman. Over the next five months, it will skip from continent to continent, crossing both the Pacific and Atlantic oceans in the process. Andre Borschberg was at the controls of the single-seater vehicle as it took off at 07:12 local time (03:12 GMT). He will share the pilot duties in due course with fellow Swiss, Bertrand Piccard. The plan is to stop off at various locations around the globe, to rest and to carry out maintenance, and also to spread a campaigning message about clean technologies."
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Solar Impulse Plane Begins Epic Global Flight More

Solar Impulse Plane Begins Epic Global Flight

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  • Hopefully the estimates of the plane's traveling capacity aren't as overblown as the articles predictions for solar energy's takeover of hydrocarbons.

    • Re: (Score:2, Insightful)

      by Anonymous Coward

      Yeah, it's hard to imagine how this technology matters to most aircraft. Don't get me wrong, it's an impressive demonstration of how far you can go on a tiny amount of power, and there are a few applications where it might matter (e.g., high altitude drones). But one look at the amount of power it actually takes to push a commercial airliner (e.g., one Boeing 777 engine produces ~75 megawatts at full throttle) and you realize solar power is completely irrelevant for that application.

      These kinds of article

      • It means they haven't done the math. Heck, even if you covered every square metre of a plane with solar cells you couldn't collect enough power. There's not enough there.

        Let's do the math, then. The specifications [wikipedia.org] of Solar Impulse-2 are available as a starting point.

        At 269.5 square meters of solar cell coverage, and an average power density [hypertextbook.com] of 1.35 kW per square meter, the maximum amount of energy the plane can harvest is about 364 kW. Now, we can use two facts to avoid the ugly world of aeronautical engineering (which I don't know): The aircraft has flown under its own power, supplied by four 17.5-horsepower motors. Those motors therefore supply about 13 kW each, for a tot

        • There are some difficulties when it comes to scaling aircraft. Very simply:
          Lift = Air_density * Velocity^2 * Coeff_lift * Wing_Area / 2
          Drag = Air_density * Velocity^2 * Coeff_drag * Wing_Area / 2
          Coeff_drag = Parasite_drag + (Coeff_lift^2 / (PI * wing_span_efficiency * wing_aspect_ratio))
          efficiency is a number in the order of 0.85 to 0.9

          So, whilst you only have to increase wing area linearly with mass (or increase speed to the square root of mass), doubling your speed quadruples your drag, and doubling your

        • A Boeing 777 is designed for speed. If you're not in a hurry, solar power might just be a reasonable option very soon.

          No, a Boeing 777 is built for efficiency and "good enough" speed. High speed rail is already killing short-haul aviation in many places around the world.
          Anyway, let's play this game. How slow is slow enough? The Solar Impulse cruises at 35 knots true airspeed - given upper altitude winds, your actual ground speed might in fact be negative on many days. Just to give you a taster of the energy requirements of "slow" flight (I have the actual manufacturer perf tables): at the lightest loadout (10000 lbs) and

          • Re: (Score:2)

            by rioki ( 1328185 )

            The thing with a solar powered plane is that at theses speeds, I think plane it the wrong design. How about a solar powered airship. You don't need power to keep it flying (almost) and it has a way higher surface area to put solar panels on. Additionally Batteries are almost neglectable, since all you need to do is provide more buoyancy through the balloon.

            • Fully agree here, a solar-powered blimp might actually not be such a bad idea, especially when your goal is primarily loitering for hours on end over something like a race track, or conducting traffic surveillance. However, for transport, especially mid- to long-distance transport, it's a horrible idea. It's akin to placing solar panels on roofs of cars and expecting to be able to use it practically, except much worse due to the much higher drag and power requirements of airplanes.

    • Re: (Score:1)

      by Anonymous Coward

      I wish the pilots well, and it's obviously an interesting project in terms of being an adventure. But to be honest, I don't really see what it's proving in terms of promoting solar power.

      I can see the potential for unmanned solar powered aircraft staying aloft for long durations, but others have already demonstrated the potential for that better, by, you know, building unmanned solar-powered planes that flew for weeks non-stop ( QinetiQ Zephyr [wikipedia.org].

      In terms of piloted aircraft, it actually just shows how bad an o

      • If you want to promote solar power, I'd say maybe use in a context where it actually looks good next to the alternatives.

        Such as in the context of powering airplanes with synthetic hydrocarbons produced by solar-powered hydrocarbon generators?

      • Re: (Score:2)

        by unrtst ( 777550 )

        With a bit of fossil fuel power, GlobalFlyer circumnavigated the globe non-stop in less than three days. An A380 could circumnavigate the globe 100 times in the five months these guys will be at it, making one stop per circumnavigation, moving 160000 people and vast amounts of cargo to the other side of the world.

        I originally misread the summary, assuming this had to be a non-stop thing, then quickly realized that's not what they said, and the 2 pilots 1 seat stood out a lot too.

        So, I agree... how is this an interesting technical achievement? Given enough time, they could throw a paper airplane around the world, or fly a glider around the world. At this point, "around the world" only seems interesting to me if it's non-stop or human powered (ex. walk around the world).

  • This will be one video I will look forward to seeing!

    • This will be one video I will look forward to seeing!

      You just want to see them pull back on the stick, you sicko!

  • Pilots (Score:2, Funny)

    by Thanshin ( 1188877 )

    Why carry pilots instead of an AI?

    If it's just for bragging about the capacity for dead weight, they could have chosen other forms for it. Like, a large pig with a funny hat. Or 150Kg worth of penguins.

    • Re: (Score:1)

      by Anonymous Coward

      Why carry pilots instead of an AI?

      It would obviously run Linux, because without a pilot, windows is unnecessary.....

    • Guess: Legalities as well as PR.

    • I don't know, I think flying a pig in a hat or 5 emperor penguins would be pretty good bragging rights.

  • Five months? (Score:3)

    by DrXym ( 126579 ) on Monday March 09, 2015 @08:15AM (#49214347)
    That's a really long time whether it is solar powered or not. If they're waiting for windows as the article says it suggests this plane runs a serious risk of having the crap kicked out of it by the weather when it attempts to fly certain legs.

    • Re:Five months? (Score:5, Interesting)

      by bsDaemon ( 87307 ) on Monday March 09, 2015 @08:53AM (#49214611)

      When SI1 did the trans-american flight, they had a stop-over at the Smithsonian's Udvar-Hazey annex out near Dulles and I went to go see it. I got to meet Bertrand Picard, which was really cool, got to touch the plane, and it was also a good excuse to go and see the rest of the collection.

      With this aircraft, we're talking about something that has the weight of a car but the wingspan of a commercial long-haul airliner. It is largely constructed out of carbon fiber, and with proportions like this I would assume that sufficiently strong winds could cause it to snap. There are also the stop-overs for educational and marketing purposes (such as spending 3 days at Dulles with the first plane 2 years ago), as well as rest and recuperation time for the pilots. They have a large ground crew, engineering team and marketing team that moves with them. It's kind of like picking up the circus and moving it to a new city and trying to get there in time before your elephants, which are on a different train.

      That said, it's one of the coolest things I've ever gotten to see in person, and Bertrand Picard is an amazing guy, from an amazing family. His grandfather was a high-altitude balloonist and scientist who inspired Professor Calculus in Tin-Tin. His father went with Challenger Deep to the bottom of the Marianas Trench. His uncle was also an explorer, Jean Picard, after whom Jean-Luc Picard of Star Trek was named. The idea for this plane came about after nearly running out of fuel during an around-the-world balloon flight in the 1990s.

      Whether we'll be seeing solar air transport on a commercial level in my lifetime or not, they're definitely attacking various engineering, scientific and social problems in a high-profile way.

      • Whether we'll be seeing solar air transport on a commercial level in my lifetime or not, they're definitely attacking various engineering, scientific and social problems in a high-profile way.

        I love the forward thinking and positive view of technology including solar power, but there's no way there are ever going to be purely *directly* solar powered commercial airplanes in the future. The power requirements are just so far removed from being able to fly at anywhere near the speeds you may want to travel at to make it a viable mode of transport. Just to give you a taste of the energy requirements needed for air travel, let's have a look at a modern airliner, .e.g a Boeing 777-200LR. From experie

        • Re: (Score:2)

          by bsDaemon ( 87307 )

          This plane is really battery powered; the solar cells charge the batteries and take in enough over the course of the day to power the batteries over night. The plane could stay aloft indefinitely, if it weren't for the pilot's biological needs.

          I agree that a 'solar powered' commercial airliner isn't realistic. however we very well may see some 'hybrid' type of aircraft in the future where large portions of the electricity necessary to run non-propulsion systems is provided by solar-rechargeable batteries (

          • I know they charge during the day and use that to run during the night, however, that's not really addressing the basic power requirement problem.
            I'm glad to see you acknowledge that this is probably not realistic to power an airliner and I'm sorry to put a dampening on your hopes for this being used to power on-board systems. The electrical draw in an airplane is minuscule compared to the mechanical load of just moving the airplane through the air. As I've calculated, the 777 requires about 100 MW of powe

        • Put simply, even from first principles, the idea of a solar-powered commercial airplane is just a non-starter.

          And you haven't even touched on the safety/risk aspects of relying on "fuel as you get it from daylight" to transport commercial quantities of people.

          At best, a "solar-powered" plane will be an electrical battery/cap-powered plane that is charged with solar-panels.

          It is hilarious and tragic that an AC response accuses you of not having enough imagination. The sad thing is that he is the one who is not using his imagination to consider the costs, challenges, and risks.

          • Oh yeah, the safety is a whole other matter :) The reason I took it from a physics angle is that if the basic physics isn't there, we don't even need to consider the question of safety and risks (which are, to a much larger degree, qualitative). It'd be like discussing the safety implications of intergalactic wormhole transportation technology.

  • Solar constant is 1kW/m^2. No way around that. (Score:4, Interesting)

    by renergy ( 1646119 ) on Monday March 09, 2015 @08:25AM (#49214411)
    Given the solar constant, i.e. the fact that there is at most 1kW per square meter of solar irradiation, there is no way this kind of planes could be used to air transport as we know it. To make the plane more powerful, way too much wing area would be needed, which would in turn reduce the speed etc. So, unfortunatelly, planes powered directly with photovoltaic panels will always be very limited in the weight they can carry. There are still applications for such kind of planes, though. (the 1kW/m^2 corresponds to a clear sky, the plane perpendicular to the impinging fotons, near the equator around noon, so the sun rays go almost perpendicularly through the atmosphere AM1.0 spectrum - simply the most favorable conditions). Photovoltaics (on a large area) powering the synthesization of hydrocarbons for conventional airplanes, renewably from air CO2 and water - that's completely different story. But it is not what this project is about.

    • surveillance
      disaster monitoring
      coms relay / internet
      electronic warfare / jamming / decoys

    • Re: (Score:2)

      by AmiMoJo ( 196126 ) *

      Solar aircraft could be a whole new class of bird that replaces some of the functionality of satellites. Much, much cheaper to build and launch, can stay up almost indefinitely and then be easily retrieved for maintenance. Think wireless communications, from "sat" phones to mobile broadcasting to wireless internet. Could be useful for surveillance applications too, e.g. deploying at high altitude over interesting areas at a price that is affordable for charities and other NGOs working on the ground.

      • If the Solar Impulse project is anything to go by, it's hopelessly dependent on good weather to be able to sustain flight. For example, if you were dealing with aviation on a regular basis, you'd know that there are these things called "upper altitude winds [aviationweather.gov]" which regularly reach speeds in excess of 100kts even at fairly low altitudes (~10000-15000 ft) and given that the Solar Impulse's cruise speed is around 35 kts, it'd simply get blown all around the place, almost like a balloon. At that point, you might
    • Comment removed based on user account deletion

    • There is a way around 1kw/m^2: multiple exciton generation. One photon generates more than one electron so current is more than the incoming light generates without the MEG techniques. The 1kw/m^2 value is based on one photon-one electron.

      Wikipedia [wikipedia.org] says:

      "Note that in the event of multiple exciton generation (MEG), quantum efficiencies of greater than 100% may be achieved since the incident photons have more than twice the band gap energy and can create two or more electron-hole pairs per incident photon."

      Ke

      • No, there is not. You are mixing the number of particles and the energy they have. You can get more free electrons than incident photons - this is really what the Quantum efficiency is about, QE = [number of electrons]/[number of incident photons]. But those "more electrons" would be at a lower energy level, which translates to lower open circuit voltage of the cell. The overall energy of the pair of electrons would still be lower than the energy of the photon that kicked them to the conduction band, i.e.

  • Mouse: What does it mean?
    Switch: It doesn't mean anything.
    Cypher: Everyone falls the first time.

  • popularize idea, not have solar airplanes (Score:4, Interesting)

    by Anonymous Coward on Monday March 09, 2015 @09:01AM (#49214651)

    I think that the effort isn't about "solar powered airplanes", since, as pointed out above, 1kW/square meter just doesn't do it. It's more about "expanding the possible" by doing something unusual. There's significant value in doing something challenging.. or do you sit at home and say, "well, it's theoretically possible to go to the North Pole on foot. I can read lots of books and figure out how to do it, theoretically. So, that problem's solved. Next...."

    How many people will be inspired by the idea in general: yes, you can do cool stuff with solar power. Some will be impractical (cargo planes with solar cells), but maybe, as someone does the calculations to show that it's impractical, they'll get an appreciation for what *is* practical (dirigibles using solar power for propulsion, but not lift, if we want to stay in aviation) , and then, they'll go out and say, let's go do that. Or, for that matter, they may not go solar power at all, but you've planted the seed of curiosity in someone

    Let's not forget, too, that at least one of the pilots is an adventurer (he's already done a non-stop around the world balloon flight) from a family of adventurers (August in balloons, Jacques to the bottom of Challenger deep)

  • why not a standard glider? (Score:1)

    by Anonymous Coward

    If this trip is over months with stops in the middle, why not use a standard glider, which in skilled hands can fly thousands of km without stopping? All gliders are solar powered.

    • Transpacific glider? I wanna see that!

  • I bet that every time the plane lands it is plugged into the grid to recharge. Saying "but it will only use solar energy from the grid" is just marketing spin.

  • While the mission will be run out of a control room in Monaco, a group of engineers will follow the plane around the globe. They have a mobile hangar to house the plane when it is not in the air.

    I wonder how big the carbon footprint of the support team is. I bet it is at least a few times as big as the carbon saved by the aircraft.

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