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View Diary: How Airliners Work - Propulsion (191 comments)

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  •  Ah, but with liquid fuel, you only have to carry (8+ / 0-)

    it halfway to where you're going.

    With the battery, you have to haul the weight all the way, so you land just as heavy as when you took off.

    So the energy density of the battery needs to be higher effectively than that of the fuel (accounting for efficiency).

    is there a mechanical engineer in the house?  

    Happy little moron, Lucky little man.
    I wish I was a moron, MY GOD, Perhaps I am!
    —Spike Milligan

    by polecat on Tue Apr 02, 2013 at 06:37:27 AM PDT

    [ Parent ]

    •  It's a differential calculation (3+ / 0-)
      Recommended by:
      polecat, TheDuckManCometh, basquebob

      and High School calculus was a long time ago.

      You have to carry some of the fuel all the way, some of it a fraction, etc ... as opposed to batteries being carried all the way, all the time.

      So the shorter the flight, the smaller the differential and that means that "long-haul" electric flying is much further off than short-haul.

      By the way, I love your sig and I have another favourite from Sopike Milligan:

      I thought I saw Jesus, on a tram.
      I said, "Are you Jesus"?
      He said, "Yes, I am".

      I hope that the quality of debate will improve,
      but I fear we will remain Democrats.

      Who is twigg?

      by twigg on Tue Apr 02, 2013 at 06:47:32 AM PDT

      [ Parent ]

      •  This diary is about simplifying math... :) /nt (1+ / 0-)
        Recommended by:
        twigg

        Happy little moron, Lucky little man.
        I wish I was a moron, MY GOD, Perhaps I am!
        —Spike Milligan

        by polecat on Tue Apr 02, 2013 at 07:28:51 AM PDT

        [ Parent ]

        •  We already hit (1+ / 0-)
          Recommended by:
          polecat

          the outer limits of my knowledge ... so I won't be complicating it further :)

          Even the "simple" math though does explain why it will be a long time before we get long haul electric aircraft :)

          I hope that the quality of debate will improve,
          but I fear we will remain Democrats.

          Who is twigg?

          by twigg on Tue Apr 02, 2013 at 07:31:01 AM PDT

          [ Parent ]

          •  Fuel-cell electric might be interesting, but (1+ / 0-)
            Recommended by:
            twigg

            turbines are really efficient and reliable, not to mention cheaper than fuel-cells.  And I don't see someone putting a Stirling engine in a plane anytime soon.

            Happy little moron, Lucky little man.
            I wish I was a moron, MY GOD, Perhaps I am!
            —Spike Milligan

            by polecat on Tue Apr 02, 2013 at 07:39:41 AM PDT

            [ Parent ]

      •  I'm not into perpetual motion, but how about (1+ / 0-)
        Recommended by:
        twigg

        an unpowered fan, a turbocharger if you will, to drive a generator to help with a top off charge to extend range, and potentially reduce battery weight?

        Republicans are like alligators. All mouth and no ears.

        by Ohiodem1 on Tue Apr 02, 2013 at 08:16:15 AM PDT

        [ Parent ]

        •  Well that is pretty much (2+ / 0-)
          Recommended by:
          Ohiodem1, polecat

          the theory behind some cars.

          I can't help but think that aircraft engineers have already thought of it.

          I imagine that a generator large enough to make a significant difference would be large, heavy and require quite a bit of fuel. They can't, for example, recover energy under braking like a car can, and overcoming the rolling resistance from a heavy car is completely different to "lift".

          So I imagine the "perpetual motion" thing applies, as does gravity and stuff :)

          I hope that the quality of debate will improve,
          but I fear we will remain Democrats.

          Who is twigg?

          by twigg on Tue Apr 02, 2013 at 08:21:45 AM PDT

          [ Parent ]

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