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Aerospace X Prize Clean Aviation: $10 million

  1. Jan 17, 2010 #1

    mheslep

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    An MIT collaboration with the X Prize foundation may soon release a proposal for a fastest coast to coast flight using only electric power.
    http://web.mit.edu/newsoffice/2009/x-prize-1217.html"

    I am thinking some of the electric ducted fan technology discussed https://www.physicsforums.com/showpost.php?p=2292842&postcount=14", and some very high end battery technology is the key, probably primary batteries if they allow it. I'll follow up later.

     
    Last edited by a moderator: Apr 24, 2017
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  3. Jan 17, 2010 #2

    mheslep

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    From earlier "[url[/URL], I considered a Bombardier CRJ900, modified with ducted fans, at 12 kWh(41k BTUs) per mile based on its gross range data given a full load of fuel. Perhaps that could be cut that in half for a more efficient, slower, jet aircraft appropriate for this contest, or 6 kWh (21k BTUs )per mile? Distance for the contest is ~2500 miles, with two stops allowed, or ~850 miles per leg, 5100 kWh (17.4 million BTU )per leg.

    [PLAIN]http://en.wikipedia.org/wiki/Zinc_air" [Broken] non rechargeable batteries achieve about 0.5 kWh per kg, giving ~11 metric tons of battery per trip leg. However, power density of metal air batteries is low, at least for commercial models. This 11 m ton pack would provide only 1.1 MW.

    Ducted fan concept:
    attachment.php?attachmentid=20065&d=1250005478.png
     
    Last edited by a moderator: May 4, 2017
  4. Jan 17, 2010 #3
    This prize seems to ignore the realities of energy storage issues. Everyone under the sun in the UAV world is trying to get high energy electric systems. I do not see what this prize is supposed to do, it's certainly not going to 'start' people thinking about electric. As for your post above, does a 'superconducting motor replaces turbine' exist outside of the imagination?
     
  5. Jan 17, 2010 #4

    mheslep

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    http://www.transportenvironment.org/Publications/prep_hand_out/lid/398" [Broken] shows aviation fuel efficiency topping out at about 1MJ / seat-km in the large jumbos, or 2 seat-miles per kWh. I'm curious as to how that metric would scale down for smaller jet aircraft - fewer seats, more overhead.
     
    Last edited by a moderator: May 4, 2017
  6. Jan 17, 2010 #5

    mheslep

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    Why, what's wrong w/ petroleum for the UAV crowd?

    ? That's not my sketch. AFRL built a 3MW motor. It's out of the paper in the link I referenced in the other thread.
    http://www.masbret.com/asc08/ASC08_Tuesday_Plenary_Electric_Aircraft.ppt
     
  7. Jan 17, 2010 #6
    Why would you want a loud, vibrating engine on a UAV?
     
  8. Jan 17, 2010 #7
    I'm looking at that ppt, and I have to ask: why would you use an electric motor to power a ducted fan, and not just use a more efficient propeller???

    Also, where are you going to get adequate energy storage?
     
  9. Jan 17, 2010 #8

    mheslep

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    Ok you're talking about military applications. Doubt that matters for the higher altitude aircraft.
     
  10. Jan 17, 2010 #9

    mheslep

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    Sorry I don't follow. What source of power are you suggesting, if not an electric motor? Edit: Perhaps you are asking: why use an electric motor instead of a traditional gas turbine? Electric motor can be >95% efficient, is quiet, as you mentioned above, and can run on electric charge that may have been generated on the ground and stored in the aircraft.

    Post #2, for purposes of this prize. 11 metric tons of battery per 850 mile leg.
     
    Last edited: Jan 17, 2010
  11. Jan 17, 2010 #10

    FredGarvin

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    Spurring on innovation is nice. That is what makes the world go round and improve. However, this, like every other electric application, is doing nothing more than shifting the sources of pollution. Most forms of clean electricity production are pretty much fixed. What's going to happen if this electric dream comes true with millions of cars and now aircraft. Crank up the coal plants. We certainly aren't doing much in nuclear and dams are pretty much fixed output. It's short sightedness at its best.

    Back on topic....there is no way to make current energy sources viable and thus useful. Like the other X prize, it is nothing more than a stunt.
     
  12. Jan 17, 2010 #11
    No, i'm saying why would you power a fan, instead of a prop. Larger rotors are more efficient.
     
  13. Jan 17, 2010 #12
    Why do you doubt this? The purpose of a UAV is to be a sensors platform. The formula for arc length is [tex]s=r d \theta[/tex]. The higher you are......
     
  14. Jan 17, 2010 #13

    mheslep

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    At least regarding the cars you must know that the power plants, even the worst of them, are much more efficient that any internal combustion engine going down the road. In moving cars to electric, conservative figures say CO2 pollution improves by almost a https://www.physicsforums.com/showpost.php?p=2507689&postcount=178" on average. SO2 may increase, if coal picks up all the additional load. In metropolitan areas pollution drops dramatically across the board, and the really bad stuff (benzene, etc) goes away completely. For me the biggest win is it does away with imported oil.

    Edit: Last, how did I forget: electric ground vehicle transport is 1/3 the cost per mile of petrol based. It's break even amortizing in the cost of the batteries - at today's price of a gas, and that's only going up.

    Or the natural gas. Just as much gas electric power capacity in the US as there is coal; gas is more expensive but much cleaner. And local.

    Nuclear http://www.world-nuclear-news.org/C-Shaw_eyes_US_reactor_uprate_market-0701104.html" [Broken] and turbine upgrades are going through - another US 4GWe while nobody was looking. Also add another 5-10GWe a year wind - useless for baseload but fine for charging batteries.

    Maybe so. First X prize didn't advance the art in any areas?
     
    Last edited by a moderator: May 4, 2017
  15. Jan 17, 2010 #14

    mheslep

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    Oh. Prop aircraft are more efficient that turbofan jet aircraft? Still? I wouldn't know. This is a contest so speed matters, so my first hunch was to go with the fan. I was guessing something under 200-300 knots would be required to keep the losses to drag down, but I am vaguely aware that the altitude, lift, and air speed couple together in matter (that's beyond me) that complicates the energy efficiency issue.
     
  16. Jan 18, 2010 #15

    FredGarvin

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    At these low speeds, yes.
     
  17. Jan 18, 2010 #16

    FredGarvin

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    Are we talking efficiency or polluting/going green?


    Nope. Not a bit.
     
  18. Jan 18, 2010 #17

    mheslep

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    Improving the first usually means improving the second, though 'going green' is not on the top of my to do list. I'm primarily after getting off imports and spending less on energy per mile. Electric transportation does that nicely, probably in aircraft too from what I can see.

    Hmm. Do you believe that's specific to the X Prize and its particulars, or every such contest: Lindberg crossing the Atlantic, etc?
     
  19. Jan 19, 2010 #18
    At what size aircraft operating at what altitude and for what distance? Why do highly efficient puddle-jumpers side with turboprops while highly efficient medium and long-haul aircraft side with turbofans?
     
  20. Jan 19, 2010 #19
    Valid point, but for this competition I fail to see why one would use an electric duct fan.
     
  21. Jan 19, 2010 #20

    mheslep

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    It is a first across the line, coast-to-coast speed contest. I see the decision (prop or turbofan) depending on the speed/efficiency curve of the chosen aircraft. If the efficiency allows it, go with a fan and get 3-400 knots.
     
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