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Transportation Science

Solar Plane Completes 24-Hour Flight 88

Posted by samzenpus
from the icarus-air dept.
asukasoryu writes "An experimental solar-powered plane landed safely Thursday after completing its first 24-hour test flight, proving that the aircraft can collect enough energy from the sun during the day to stay aloft all night. The record feat completes seven years of planning and brings the Swiss-led project one step closer to its goal of circling the globe using only energy from the sun. The team will now set its sights on an Atlantic crossing, before attempting a round-the-world flight in 2013." We ran a story about the flight's departure yesterday.
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Solar Plane Completes 24-Hour Flight

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  • Uses (Score:5, Interesting)

    by IflyRC (956454) on Thursday July 08, 2010 @11:07AM (#32840252)
    I think that this technology will show up in military drones before we'll ever see it in general aviation. It sounds great for smaller drones that can stay aloft without ever needing to refuel. Speed is also going to be a huge factor. Most drones, I would think, do not need to fly that fast as most can be launched near the location in which they need to patrol.
    • I think that this technology will show up in military drones before we'll ever see it in general aviation. It sounds great for smaller drones that can stay aloft without ever needing to refuel. Speed is also going to be a huge factor. Most drones, I would think, do not need to fly that fast as most can be launched near the location in which they need to patrol.

      Unfortunately, that is the fate of every great invention. First the military uses are abused. Civil applications almost always appear later.

      As much as I dislike the developments of autonomous small drones that can fly practically forever... weapons development shouldn't discourage mankind from making inventions and great designs.

      At the same time, I wonder how long until there are government / police drones flying at several km altitude over my house continuously (checking on the fact that I have nothing to

      • >> First the military uses are abused. Civil applications...

        [are abused] later.

      • The military spends the money to perfect it, or at least bring it to a generally useful stage. At the point that commercial interests get their hands on it, most of the major bugs in the core functionality have been worked out, allowing the erstwhile vendors to spend their money adding bells & whistles. By the time we consumers get our grubby paws on it, the major pitfalls have been addressed.
    • by Cytotoxic (245301)

      What ever happened to Helios, the NASA solar powered "atmospheric satellite"? It was like a giant version of the human-powered Gossamer Condor, but unmanned and solar powered. It flew to about 100k feet almost a decade ago and was designed to stay aloft for months. They had some kind of failure that resulted in a crash and that's the last I've heard of it.

      • Re: (Score:2, Interesting)

        by kg8484 (1755554)

        What ever happened to Helios, the NASA solar powered "atmospheric satellite"?

        I think you answered your own question:

        They had some kind of failure that resulted in a crash

        More info on Wikipedia [wikipedia.org].

        • by radtea (464814)

          More info...

          But none of that info relates to why the ERAST programme was terminated in 2003.

          Obviously a single failure of a single prototype wouldn't be enough to cancel an entire programme that was intended to lead the way toward a new type of long-term sustainable aerial platforms. If that were the case then Apollo would have never come close to getting off the ground! We all know that governments are needed to fund this kind of enterprise because only they have the long time horizons and staying power to get the j

    • Probably not (Score:2, Interesting)

      by gsgriffin (1195771)
      Um, maybe not. Huge wing span and slow? Perfect target. Not a useful payload. Hugh amounts of electronics needed by a drone and....the military doesn't care about the costs of fuel or operation. Land it. Fuel it up. Send it out again. This is not a military technology.

      We'll see this improve over time where costs will come down and eventually people that like to fly gliders, or hang glide or whatever (and have tons of money) will have items like this for play. We'll probably also have the technology b
      • Re:Probably not (Score:5, Interesting)

        by Chibi Merrow (226057) <{ten.ytinifniyeknom} {ta} {worremrm}> on Thursday July 08, 2010 @12:06PM (#32841040) Homepage Journal

        Um, maybe not. Huge wing span and slow? Perfect target. Not a useful payload. Hugh amounts of electronics needed by a drone and....the military doesn't care about the costs of fuel or operation. Land it. Fuel it up. Send it out again. This is not a military technology.

        Disclaimer: I work with the FAA on UAS system integration into the NAS, so my opinions are a bit coloured by my experiences.

        I don't think you're imaginative enough about the types of missions our military wants to fly. Yes, a slow moving large UAS is not useful for low altitude fast turnaround tactical type missions, but that's what a Raven [wikipedia.org] is for.

        Something like this, though, would be invaluable for long duration surveillance type missions, like monitoring borders in Iraq and Afghanistan for weapons smuggling. Stick something like this at high altitudes to do autonomous surveillance and deploy more agile solutions on an as-needed basis to check out potential targets the high altitude UAS detects. The plans for UAS systems are very layered approaches, with room for little soldier-deployable RC craft, short ranged attack/reconnaissance craft, and high altitude, long-range, long duration surveillance craft.

        You might think that the military will just "land and refuel" a UAS when necessary because money is no object, but that implies the existence of established airbases in the theater the UAS will be operating in, or long travel times to and from its mission which further reduce their loiter time. So, no, it's not as simple as "money is no object".

        Honestly, the period that UASes are most at risk is on landing and take-off, both from hostile ground fire and just simple things like wind gusts dashing them against the ground or knocking them over. Having a UAS system that rarely has to land and take off would immensely improve their reliability and life expectancy.

        So in summary, yeah, I think the military would be very interested in this type of technology.

        • all I read are the precursors to an affordable, 24/7, domestically deployed Panopticon system. Gotta think of the children, and if you have nothing to hide...
          • Re: (Score:3, Interesting)

            by Chibi Merrow (226057)

            They already do this sort of stuff with helicopters and aircraft for law enforcement purposes--at least UASes are a cheaper way to do it with less risk to human life. If a UAS crashes oh well we're out some money, if a police chopper smashes into a news chopper, it's bad times all around...
            Never mind the law enforcement implications, the immense benefit for things like tracking/coordinating responses to wildfires, cataloguing herds of wildlife, providing communication to remote settlements... Isn't Slashdot

            • Uh, if a plane with a 200 foot wingspan crashes into a dense urban area that its patrolling 24/7 you don't think its bad times all around?

              • As opposed to a manned aircraft that is orders of magnitude heavier and full of highly flammable fuel?

            • Isn't Slashdot the home of 'just because it can be used for something bad doesn't make it wrong!' type arguments? :)

              Ah yes, the famous "Don't hate the play--"...wait, that's the opposite. I can agree with you. If we don't want this thing watching us, perhaps we should speak up when governments put these policies into place. It is our government, after all. Don't let that get in the way of progress.

            • by Shotgun (30919)

              Since it's cheaper, we can expect a reduction in the police budget and some lowering of taxes. Right?

              Wrong. We can expect an expansion on surveillance activities, like UAV's patrolling the highways for speeders, or more patrols for people growing the wrong weed in their backyard. There will still be no budget for tracking wildlife herds or providing communication to remote settlements.

      • Re:Probably not (Score:5, Insightful)

        by DerekLyons (302214) <fairwater@gmail. c o m> on Thursday July 08, 2010 @01:28PM (#32842258) Homepage

        the military doesn't care about the costs of fuel or operation.

        I'm guessing all those times I spent at the end of a fiscal quarter or a fiscal year hoping I had enough budget to buy my spares and consumables were figments of my imagination. The same goes for the gradual accumulation of ships at the piers towards the end of a quarter, after all they didn't have a quarterly fuel budget... (And this was at the height of the Cold War!)
         
        Or, IOW, bovine exhaust. The military does care about the costs of fuel and operations as they don't have a blank check.
         

        Land it. Fuel it up. Send it out again

        The military also cares deeply about endurance and cycle time - because the shorter they are, the more units you need to maintain coverage. All else being equal (and taking budget into account) they'll chose the system with maximum endurance and minimum cycle time consistent with minimal life cycle costs.

      • by robi2106 (464558)

        I doubt that this sort of vehicle flys in low altitude. IT is probably a high altitude flyer (greater sunlight absorption, more stable air currents).

        • Of course, by more stable air currents you're referring to 100+ MPH winds high aloft? Imagine the power needed to keep the speed just to hover over a spot let alone make headway. This is why commercial flights transcontinental can be so different from city to city depending on the direction of flight (in relation to winds aloft). Of course your very correct if the purpose is a one-way flight using the winds to get you there...like a balloon would.
          • You really don't know what you're talking about...

            NASA had a solar powered craft at 96,000ft in 2001. Reality disagrees with your theories. High altitude currents are not a problem as they generally ARE stable, as in moving in the same direction and same speed pretty consistently. The problem for a UAS is low altitude winds, which can change direction and intensity very rapidly and lead to loss of control or even breakup. NASA's Helios (the one that flew at 96,000 ft) had no problems whatsoever at altitude.

    • by kimgkimg (957949)
      Or alternatives to satellite repeaters? Just have a blanket of these encircling areas 24/7.
    • by Yvanhoe (564877)
      Well, currently this is a civilian project and it has a lead. Military projects are often incredibly conservative.
    • by Reilaos (1544173)
      Good point. Drones also benefit from not freezing to death in 20 below conditions at night.
  • by SpacePunk (17960)

    Ok, it works fine on one of the days of the year that has the longest period of daylight, but how well does it work on a day that has the shortest period of daylight? Just because something works in optimum conditions doesn't make it noteworthy.

    • by IflyRC (956454)
      My guess would be "not very well". Its basically a glider, 193 ft wingspan is HUGE. Thats the size of an airbus A330. I'm not certain if the wingspan is needed to house the 12k plus solar panels or if the wing area is needed in order to provide extremely low wingloading while carrying an extremely heavy, large number of batteries. Granted as battery tech gets better, less will be needed to store the required energy and as solar panels become more efficient - hopefully we won't need as many to charge the b
    • by eln (21727) on Thursday July 08, 2010 @11:27AM (#32840504) Homepage
      You're right. The original Wright Flyer barely made it off the ground in optimum conditions, there's no way it would have made it in poor weather, and it certainly wouldn't get me across the country in a reasonable amount of time. Clearly this whole heavier-than-air flight nonsense is wildly impractical and we should stop trying to make it work.

      Solar powered flight is evolving just like any technology, and it's currently in its infancy. It may or may not ever prove to be practical, but abandoning it just because an experimental craft has shortcomings we don't think a fully mature product should have would be silly.
      • Re: (Score:1, Troll)

        by MozeeToby (1163751)

        Hardly the same thing, in my opinion. We know the power densities required to move cargo and people through the air at acceptable speeds and solar just cannot realistically supply it. This thing has the wing span of a 777 and the carrying capacity of an ultralight. Even assuming that you can increase the efficiency of the solar cells by five times you're still not talking anything remotely practical for commercial use.

        Don't get me wrong, it's some very impressive technology. An unmanned variant might so

        • by blackfrancis75 (911664) on Thursday July 08, 2010 @11:58AM (#32840918)

          you're still not talking anything remotely practical for commercial use.

          If such a plane can be made to carry even small amounts of cargo across the earth - slowly, but faster than terrestrial speeds - and it's operating costs are negligible, wouldn't that have a variety of commercial applications?

          An unmanned variant might someday even has some military and civilian uses

          Contradicts first statement.

          it's never going to replace our chemically powered, high speed transportation aircraft.

          Possibly true, but irrelevant.

          • by bkeahl (1688280)
            I wouldn't say he was contradicting himself. He said "... still not talking anything remotely practical ...", that does not mean it can never work, just that we're not there yet.

            He then says it might be practical someday, perhaps wanting to make it clear he's not opposed to researching it and being hopeful it'll become practical someday.

            Simple physics says it'll never replace chemically powered high speed aircraft. So he was right there. Of course, you just decided it was "irrelevant" for some reason.
        • Re: (Score:2, Troll)

          by Molochi (555357)

          Semi-related to this (the power density bit). There was a design for small arms ammunition in the '90s that used an electrical heating element. The propellant was water flashed into superheated steam. I don't know what the momentum impulse energy would be for superheated steam, but the escaping vapor would at least be supersonic, making it an interesting idea for a renewable propellant.

          Just find a source for more water (clouds) than you are using and you could stay up indefinitely. Heh, an "atmospheric buss

    • Just because something works in optimum conditions doesn't make it noteworthy.

      That's a load of crock.

      The LHC only works in optimum conditions and you don't think that's noteworthy?

      Seriously, the number of things that "only work in optimum conditions" is beyond comprehension. My computer would probably go on the fritz if it were to pass through a super strong magnetic field but you don't see me calling it useless.

      • by SpacePunk (17960)

        The LHC is noteworthy for breaking down.

        Of course, we aren't talking about the LHC or your Atom powered computer. I simply do not see the hoopla over the aircraft until it flies on a day with the shortest period of daylight. Then I'll think it's fairly 'neat'. The lack of any serious payload is another thing entirely. Any jackass with enough money could have done this. It's a small, tiny, increment in air flight technology. Whoop it up all you like, eventually it won't lead anywhere useful.

  • Hybrid Planes (Score:3, Interesting)

    by COMON$ (806135) on Thursday July 08, 2010 @11:18AM (#32840378) Journal
    Which makes me wonder, can enough energy be gathered to help offset the cost of jet fuel in existing commercial planes? You are above the clouds so you have a steady supply of power, but I dont know anything about the amount of energy a jet plane needs. Perhaps solar cells just aren't efficient enough yet? If that is the case, how efficient would they need to be?
    • Re: (Score:1, Troll)

      by IflyRC (956454)
      I'm not sure how you would get solar to work with a jet engine unless you switched over to a ducted fan type setup. A jet engine requires combustion. You would need two completely different propulsion systems on board the aircraft...and that adds weight. With the additional weight, power needs will increase, lift generation will need to increase and your stall speed increases.
      • by wagnerrp (1305589)

        A jet engine requires combustion.

        No, a jet engine requires heat input. You can provide that heat in any manner you please, including electric resistance heating.

        I'm not sure how you would get solar to work with a jet engine unless you switched over to a ducted fan type setup.

        Nearly all jet engines in use are ducted fans.

        • by jshackney (99735)

          Nearly all jet engines in use are ducted fans.

          Technically, no, they aren't.

          A ducted fan utilizes an engine to turn a propeller which is mounted inside a tube. Propulsion is provided by the propeller moving the air. The fan shroud makes the propeller more efficient.

          A [turbo]jet utilizes combustion/exhaust to turn a turbine which turns a compressor and generates high pressure exhaust gases which are forced out the back of the engine. There's no (or pathetically little) thrust from the internal components of the jet engine, thrust is a result of the hot g

      • by Shotgun (30919)

        You could have the solar panels assist in driving the existing fans. Less fuel would be required to get the same cruise power. In this arrangement, no moving parts are added. The extra power from the solar panels basically becomes a solid state driver.

        The question then breaks down to what is the payoff of layering the upper skin of the aircraft with solar panels. You would already have an aluminum substrate. Could one of the newer printing techonologies work? With the switch to composite technologies,

    • Re: (Score:3, Interesting)

      by gurudyne (126096)

      If solar cells were 100% efficient, they might be able to gather enough energy to power the entertainment electronics on commercial aircraft.

      Yes, you have a steady supply of power but you would be lucky to gather one (1) kw per square meter on cells oriented 90 degrees to the Sun. Since that would probably not be optimally aligned to the flight direction, your collection would be less.

      • Why on earth would this be a troll? The estimate seems to be in the right ball park.

        • Re: (Score:3, Insightful)

          by COMON$ (806135)
          looks like someone had mod points and went down the thread marking troll. This is what we refer to as someone abusing their mod points. One of the more blatant ones I have seen.
    • by Nyeerrmm (940927)

      State of the art solar aircraft look a lot like gliders. Huge wings, tiny fuselages, and slow speeds. And these are using top of the line, 25-30% efficient cells. On first glance, this tells me without a drastic improvement efficiency a cost effective passenger liner is out of the question for now.

      However, there's one caveat to that. Most of those planes are concentrating on extremely long-duration flight, and a major component of the weight is the battery mass required to store all the energy for the n

      • by COMON$ (806135)
        Ya I was just thinking as a supplement. there is a large surface area on planes and even if you could reduce the cost of a flight by 1% you would think that would amount to a huge cost savings overall.
      • by Shotgun (30919)

        Most light aircraft spend the vast amount of their lifetime sitting around in the sun on a airport tarmac some place. If you're going to make a battery powered solar plane, give it a two hour endurance and have it charged with thin film panels on the wings. The owner won't be back out to fly until the next weekend anyhow.

    • Re: (Score:3, Informative)

      by wagnerrp (1305589)

      You are above the clouds so you have a steady supply of power, but I dont know anything about the amount of energy a jet plane needs.

      Going off some numbers for a (relatively old and inefficient) 747, you burn through ~5gal of kerosene per mile, at 550mph. That's about 6lbs of fuel per second, or around 120MW of thermal output. Using average efficiency available for commercial solar panels, you're looking at a half square kilometer array to power a single aircraft at cruise conditions. If you were to replace the turbine powered ducted fan engines for electric powered ones, you would cut that power consumption in about half.

      • by Shotgun (30919)

        But what if you only used the solar generated energy to augment the jet engine's intake system? For instance, build the first state of the intake with a ring of inductors? Increase range. Provide emergency electric/power backup. Possibly extend glide range. It would be a relatively cheap and easy retrofit.

        • by wagnerrp (1305589)
          If you covered the entire wing and fuselage with solar panels, you might get around 150kW out of it. That's 0.1% of the engine power at cruise. You probably wouldn't even provide enough thrust to offset the additional weight of the system, much less make it economical.
    • Re:Hybrid Planes (Score:5, Interesting)

      by BlackPignouf (1017012) on Thursday July 08, 2010 @12:04PM (#32841010)

      Assuming that the solar irradiance you get on top of the atmosphere is 1360W/m2, 1 square meter worth of solar panel with 20% efficiency (e.g. the best SunPower crystalline silicon modules) would generate 270W of electricity.

      Airbus claims that the A380 consumes 3l/100km.passenger of fuel.
      At Mach 0.85 (~250m/s at 10km altitude), this represents 27l/h.passenger.

      Assuming 10kWh/l of fuel energy content and 50% efficiency of the turbofans (pulled out of my ...), that amounts to 135kW of mechanical power needed for every single passenger.

      Assuming an electrical motor with 100% efficiency, you would need 500m2 of solar panels for every passenger to generate the required electricity, but only during the day.

      The plane from TFA seems to have 200m2 of solar panels with 12% efficiency. It can get away with it because it is much lighter and flights much slower.

      Conclusion : The orders of magnitude just don't match, even with 100% efficiency => Commercial flights as we know them & photovoltaics are incompatible.

  • Seriously, look at the photographs. This thing has a 60m wingspan, is covered in cells, made of carbon fibre and weighs just 1.6 tons. It's fantastically light for its size - I shudder to think how much more efficient your solar cells would need to be to get even a small passenger airliner in the air.

    • Re: (Score:1, Interesting)

      by Anonymous Coward

      From the article:

      But while the team said this proves that emissions-free air travel is possible, it doesn't see solar technology replacing conventional jet propulsion any time soon.
      Instead, the project's overarching purpose is to test and promote new energy-efficient technologies.

    • Re: (Score:1, Interesting)

      by Anonymous Coward

      I think the goal of the project is more to 'promote solar energy' rather than to develop a commercial airliner.

      If they wanted to produce a useful airplane, they would probably use solar power to split water into hydrogen and oxygen on the ground, and use the hydrogen as fuel for some kind of jet/prop engine. This would be far more practical than using 400kg of Lithium-ion polymer batteries to store the energy and they would probably end up with a plane that can to some degree compete with todays planes in t

      • by wagnerrp (1305589)

        If they wanted to produce a useful airplane, they would probably use solar power to split water into hydrogen and oxygen on the ground, and use the hydrogen as fuel for some kind of jet/prop engine.

        Then you would have to land to refill. The purpose of this kind of aircraft is that you can load it down with some electronics, radio, or other sensor package, and let it loiter over an area for months on end. Ideal for surveillance drones, atmospheric testing, flying cell transponders, etc...

    • Still I'd like to have one in the shed so I can take it out for a cruise on a nice sunny day.

      and if I dont feel like going for a cruise on a sunny day I'll just leave it outside, connected to a grid tie inverter
  • by Anonymous Coward

    The flight took 26 [bbc.co.uk] metric (Swiss) hours.
    Wasn't aware of imperial hours existence :-)

  • by strack (1051390)
    they really should put some large solar panel surfaces on the middle part, have some large wing areas sticking out from the middle, not really for lift, but to gather more sun. im kinda suprised they didnt make the wings longer from back to front, for more solar panel area.
    • Re: (Score:3, Informative)

      by wagnerrp (1305589)

      im kinda suprised they didnt make the wings longer from back to front, for more solar panel area.

      Larger chord length would result in lower aspect ratio, higher induced drag, and lower efficiency. They could put propellers out on the wingtip to counter induced drag...

  • by tomhath (637240) on Thursday July 08, 2010 @12:40PM (#32841554)

    What they proved is that they can make it through the night with fully charged batteries. What they didn't say in the article is whether the batteries would be charged back up by tonight if they had stayed aloft.

    Still an impressive feat, but I'll be even more impressed when they can show that it fully recharges while in flight.

    • by The Bean (23214)

      Be impressed, what you said is basically what this flight set out to, and did, prove.

    • Re: (Score:3, Informative)

      by jklovanc (1603149)

      Check out http://www.solarimpulse.com/nightFlights/charts.php [solarimpulse.com]. Notice that it took 6.5 hours to go from 46% charge to 100%charge. By extrapolation it should take about 12 hours to get a full charge though that may not be true as the solar cell efficiency seems to decrease as the cells cool below 0 degrees. Here are a few other interesting points from the graph.

      1. They need a more accurate speed and altitude sensor. There are quite a few spikes in the charts. Some of them have "disappeared". They were probab

      • by tomhath (637240)
        The chart I see shows "Battery Load", not Charge. Am I not understanding something? It looks to me that they climbed to 9000M and kept it at full power as they glided down to 2000M overnight. The generator did very little for the last 16 hours of the flight.
        • by jklovanc (1603149)

          Considering that the battery "load" level went up when the motors were using less power than the solar cells were providing and it went down when the motors were used during the night I would surmise that they meant battery charge.

          They are not using a generator; They are using solar cells. The cells did very little because the batteries were full or there was no sun out during the last 16 hours.

    • Yeah, to really drive the point home I'd like to see them launch it during the day, stay aloft that night, fly around the next day recharging the batteries, and then stay up all night again.

      From the data this looks like they could do this, that'd be cool.

  • Unless the batteries contained at least as much charge on landing as they did at takeoff, this does not prove "that the aircraft can collect enough energy from the sun during the day to stay aloft all night".

    The real test will be when the plane can stay continuously aloft for a week or more. That will mean they're either collecting enough energy during the day to keep them aloft through the night, or else they've made a major breakthrough in battery technology, which would be even more exciting.

  • Well I learned that American Airlines now has Wi-Fi in-flight. The blurb next to the video preview told me so. And in case I missed it, the big 20-second ad comes up before the Solar Plane video, helpfully building anticipation. Then in case I forget, I get a nice reminder at the bottom of the video, all the way up to the infomercial.

    Has msnbc always been like this?

  • There are a lot of possibilites if this can be developed. The roof of cars could be solar panel(s). This would be in addition to the electric cars power source and once the cost of producing solar panel comes down perhaps more people will use it on their homes. Of course; it doesn't look good so that could also be a deterent to the look of your home.

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