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    •  
      CommentAuthorfostertom
    • CommentTimeOct 9th 2017
     
    Posted By: finnian500m2 of wing area: 20% efficiency panels would get you
    roughly 100kW of power with sun directly overhead
    What solar intensity are you assuming? Should be a lot more than on the ground.
    •  
      CommentAuthorSteamyTea
    • CommentTimeOct 9th 2017
     
    20% is pretty good and not much more than 1400W/m^2 even at altitude.
    But let us say that they are 100% efficient, still leaves a really large gap. 500 kW compared to 5 MW.
    • CommentAuthorfinnian
    • CommentTimeOct 9th 2017
     
    I was assuming 1kW/m2: you would get 1.3kW/m2 at extreme altitude. This kind of rough estimate is only accurate to one significant figure.

    Doesn't actually make that much difference of course... this is massively unfeasible, so factors of 30% aren't going to help.
    •  
      CommentAuthorfostertom
    • CommentTimeOct 9th 2017 edited
     
    Posted By: finnianPower needed at cruise is about 50MW
    Is that the 747? What for a 10 seat slow big-wing 'air-taxi'?

    Renewablejohn's ref https://cleantechnica.com/2017/05/06/solarstratos-solar-airplane-aims-stratosphere-fueled-sunshine/ defines the sustained-PV model - no one's suggesting the air-taxi would be that - but given the wing area it would be daft to not top-up in flight when possible, even if at night/in winter/in the north it relies entirely on ground-charging.
    •  
      CommentAuthordjh
    • CommentTimeOct 9th 2017
     
    Posted By: fostertomgiven the wing area it would be daft to not top-up in flight when possible

    That's not at all obvious. You would have to calculate the cost of the extra weight of the solar panels and set that against the benefit of the electrical energy generated.
    •  
      CommentAuthorfostertom
    • CommentTimeOct 9th 2017
     
    Thin-film solar panels near to commercialisation weigh no more than wallpaper.
    •  
      CommentAuthordjh
    • CommentTimeOct 9th 2017
     
    Posted By: fostertomThin-film solar panels near to commercialisation weigh no more than wallpaper.

    Even if that is true, they don't wallpaper airplane wings.
  1.  
    <blockquote><cite>Posted By: djh</cite><blockquote><cite>Posted By: fostertom</cite>Thin-film solar panels near to commercialisation weigh no more than wallpaper.</blockquote>
    Even if that is true, they don't wallpaper airplane wings.</blockquote>

    No they dont wallpaper aeroplanes they create purpose built machines with solar incorporated capable of flying over the alps. This is the two seat version flying since 2014.

    http://allthingsaero.com/general-aviation/experimental-aircraft/gallery-solar-powered-airplane-is-here

    Its the first commercial solar plane capable of recharging its batteries whilst in flight.
    •  
      CommentAuthorSteamyTea
    • CommentTimeOct 9th 2017
     
    Posted By: fostertomThin-film solar panels
    I was waiting for that, along with monocrystalline.
  2.  
    <blockquote><cite>Posted By: finnian</cite>I was assuming 1kW/m2: you would get 1.3kW/m2 at extreme altitude. This kind of rough estimate is only accurate to one significant figure.

    Doesn't actually make that much difference of course... this is massively unfeasible, so factors of 30% aren't going to help.</blockquote>

    You can keep your 747 cattle trucks in the sky.

    This is more my kind of travel which should be doable with electric.

    http://www.airjuan.com/airjuan-fleet-cessna-grand-caravan-seaplane.php
    •  
      CommentAuthordjh
    • CommentTimeOct 9th 2017
     
    Posted By: renewablejohn
    Posted By: djh
    Posted By: fostertomThin-film solar panels near to commercialisation weigh no more than wallpaper.

    Even if that is true, they don't wallpaper airplane wings.


    No they dont wallpaper aeroplanes they create purpose built machines with solar incorporated capable of flying over the alps. This is the two seat version flying since 2014.

    http://allthingsaero.com/general-aviation/experimental-aircraft/gallery-solar-powered-airplane-is-here" rel="nofollow" >http://allthingsaero.com/general-aviation/experimental-aircraft/gallery-solar-powered-airplane-is-here

    Its the first commercial solar plane capable of recharging its batteries whilst in flight.

    That's really not relevant to my point.
    •  
      CommentAuthordjh
    • CommentTimeOct 9th 2017
     
    Posted By: renewablejohnThis is more my kind of travel which should be doable with electric.

    http://www.airjuan.com/airjuan-fleet-cessna-grand-caravan-seaplane.php" rel="nofollow" >http://www.airjuan.com/airjuan-fleet-cessna-grand-caravan-seaplane.php

    But specifically, it isn't electric and is completely irrelevant to the discussion.
    •  
      CommentAuthorSteamyTea
    • CommentTimeOct 9th 2017 edited
     
    I just re-read a bit about Solar Impulse.
    Seems it did 25,000 miles with a flight time of 23 days, so a bit over 1000 a day, 45 MPH. But that was over 16 1/2 months, so 1.8 MPH.
    Cost about $20 Million.
    Takes 1 person, the pilot.
    And that is the best there is as it i proven.
  3.  
    <blockquote><cite>Posted By: djh</cite><blockquote></blockquote></blockquote>

    Not irrelevant as that is the size of aeroplane Airbus and Siemens are developing.
  4.  
    <blockquote><cite>Posted By: SteamyTea</cite>I just re-read a bit about Solar Impulse.
    Seems it did 25,000 miles with a flight time of 23 days, so a bit over 1000 a day, 45 MPH. But that was over 16 1/2 months, so 1.8 MPH.
    Cost about $20 Million.
    Takes 1 person, the pilot.
    And that is the best there is as it i proven.</blockquote>

    Nothing like a bit of bias reporting. Yes it did take a long time to complete the journey but that was because they cooked the batteries and had to wait for replacements. As for the best your a long way off with Siemens currently holding the performance records and probably the Duo is the current most useful long distance plane.
    •  
      CommentAuthorSteamyTea
    • CommentTimeOct 10th 2017
     
    Are you referring to this:
    https://www.siemens.com/press/en/feature/2015/corporate/2015-03-electromotor.php?content[]=Corp
    I don't think it is really relevant to passenger planes.
    Fake news.
    • CommentAuthorgyrogear
    • CommentTimeOct 10th 2017
     
    "Next you will be saying you cannot power a plane with a steam engine".

    On The Contrary: big steam engine, powered by a ground- or space-based laser to boot.

    (for cost-efficiency, laser generated by a decent wood-burner...)

    gg
  5.  
    Posted By: gyrogear"Next you will be saying you cannot power a plane with a steam engine".

    On The Contrary: big steam engine, powered by a ground- or space-based laser to boot.

    (for cost-efficiency, laser generated by a decent wood-burner...)

    gg


    I was actually referring to the remarkable Doble powered steam aeroplane flying in 1934. With the advance in solar thermal power generation an updated version could well be a viable alternative to batteries.
  6.  
    Posted By: SteamyTeaAre you referring to this:
    https://www.siemens.com/press/en/feature/2015/corporate/2015-03-electromotor.php?content[]=Corp" rel="nofollow" >https://www.siemens.com/press/en/feature/2015/corporate/2015-03-electromotor.php?content[]=Corp
    I don't think it is really relevant to passenger planes.
    Fake news.


    If you actually read the article you quoted you would see its this new generation of engines which is being used in collaboration with Airbus for there next generation of aircraft.
    • CommentAuthorgyrogear
    • CommentTimeOct 10th 2017
     
    Posted By: renewablejohnwas actually referring to the remarkable Doble powered steam aeroplane flying in 1934.


    Nice one, I was totally unaware of this technology...

    Here is another video...

    https://www.youtube.com/watch?v=2TtHOkgwrk8

    gg
    •  
      CommentAuthorSteamyTea
    • CommentTimeOct 10th 2017 edited
     
    Posted By: renewablejohnIf you actually read the article you quoted you would see its this new generation of engines which is being used in collaboration with Airbus for there next generation of aircraft.
    Yes I read it, 5 kW/kg for the motor, nothing about batteries.
    If goes at 350 km/h (ish) and can toe a glider up. Has a reasonable rate of climb too.
    But John, it is not a 100 seater passenger plane that can do a 100 miles and meet all the regulatory law.
    And even of the air frame and motor weighed nothing, I suspect, but cannot brothered to calculate and you would only come back with some spurious claim about something, that the mass of the batteries would will make it way too heavy.

    As for a modern steam plane, come on, get real.
    •  
      CommentAuthorfostertom
    • CommentTimeOct 15th 2017 edited
     
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