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

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  •  Model Electric aircraft (4+ / 0-)
    Recommended by:
    elfling, Orinoco, basquebob, Bisbonian

    fly extremely well, and very fast ... but not for very long.

    As you said ... it's the energy storage that is the issue. Those batteries are very heavy.

    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 06:21:37 AM PDT

    [ Parent ]

    •  That's likely to change (2+ / 0-)
      Recommended by:
      twigg, Orinoco

      If and when it does, is there any other reason this won't work? It seems like the logical future of aviation for all sorts of reasons, most of them green.

      "Liberty without virtue would be no blessing to us" - Benjamin Rush, 1777

      by kovie on Tue Apr 02, 2013 at 06:25:19 AM PDT

      [ Parent ]

      •  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 ]

      •  About 20 minutes of flying (2+ / 0-)
        Recommended by:
        lazybum, Orinoco

        is what I could expect from an electric aircraft, compared with maybe two hours from nitro weighing about the same, so there is much progress to be made before they are comparable.

        20 minutes is quite long enough for a hobby, but it wouldn't get me from Tulsa to Dallas at full scale.

        I agree on green reasons. Even electricity generated on a large scale, from fossil fuels, is greener than trying to do it in individual engines. When we can generate power from renewables on a large scale then we will really be in business.

        I don't know quite how green cars like the Volt really are, but they are quite heavy so maybe that's a blind alley for aircraft and we need something better. Of course when we get it, cars will benefit too.

        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 06:42:31 AM PDT

        [ Parent ]

      •  Engine weight (1+ / 0-)
        Recommended by:
        lazybum

        you are replacing one or two turbine blades with an electric motor, which has heavy coils of wire and permanent magnets, or more heavy coils of wire, plus magnet cores.

        Electric motors might be an ideal solution for powering zeppelins, where the high heat of a turbine engine would be a problem.

        "The problems of incompetent, corrupt, corporatist government are incompetence, corruption and corporatism, not government." Jerome a Paris

        by Orinoco on Tue Apr 02, 2013 at 11:15:52 AM PDT

        [ Parent ]

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