How far are we from the perfect electric "homebuilt" ?

Discussion in 'Hangar Flying' started by Speedboat100, Aug 20, 2019.

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  1. Aug 20, 2019 #1

    Speedboat100

    Speedboat100

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    I mean that if we could get the most unforeseen ideas implemented to an electric aeroplane...how far are we from this perfect situation ?

    I assume it means:

    1. New structural ideas
    2. Better engines
    3. Battery developement
    4. Aerodynamical innovations

    This is very necessary to get developement fast..as the energy density of batteries is about 1/20th at the best cases from fuel.

    I think we can make 65-70 % progress compared to the systems today flying....in 10 years.

    Electric engines are simple and light...which is a good thing ( I opened one ).
     

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  2. Aug 20, 2019 #2

    Speedboat100

    Speedboat100

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    I read somewhere that the biggest mistake is trying to convert an existing type of gas powered plane to an electric one....is there truth to this. I think there is.
     
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  3. Aug 20, 2019 #3

    radfordc

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    New designs and motors may help a little, but it's batteries that are the critical path to practical electric planes. Lithium-polymers are 2-3 times better than Nickle Cadmiums...we now need something at least 2-3 times better than Li-Po's.
     
  4. Aug 20, 2019 #4

    stanislavz

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  5. Aug 20, 2019 #5

    Tiger Tim

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    “Perfect” is a moving target and one that’s probably best if it’s always out of reach. How awful would it be if we knew we had reached the peak and there was nowhere left to go?
     
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  6. Aug 20, 2019 #6

    Speedboat100

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    They fly 2 hrs + if they want to:

    Lithium-Nickel-Manganese-Cobalt batteries.
     
  7. Aug 20, 2019 #7

    Speedboat100

    Speedboat100

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    That reduction gear on bike hub motors would already be one advancement...you could run a bigger dia prop.
     
  8. Aug 20, 2019 #8

    Hephaestus

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    In RC world we stopped using gearboxes and started using appropriate sized motors. Introducing drivetrain losses - isn't a benefit. It's a stopgap because you couldn't find an appropriate motor.
     
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  9. Aug 20, 2019 #9

    pictsidhe

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    A direct drive motor is going to be much heavier than a geared motor.
     
  10. Aug 20, 2019 #10

    stanislavz

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    In most cases no. You still need constant power in tens of minuts. Not few second burst. Energy packed to dense - active water cooling to cooe with.

    Make it bigger and flatter - a lot of active area for cooling.
     
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  11. Aug 20, 2019 #11

    Hephaestus

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    Psru design for electric is no easier than gas.

    Even in the RC world with 40 years of practice gearboxes for electric motors don't have great reliability.
     
  12. Aug 20, 2019 #12

    Speedboat100

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    But they seem to work ok in the electric bicycle world !
     
    Last edited: Aug 20, 2019
  13. Aug 20, 2019 #13

    Hephaestus

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    Different loads different forces.
     
  14. Aug 20, 2019 #14

    Speedboat100

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    I am also worried about the cooling..if the gear is in the front.
     
  15. Aug 20, 2019 #15

    stanislavz

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    All still goes to power / cooling surface. You cant put more than 1.2 Tesla in iron core before saturation. Independant of shape.

    And pancake shape will provide way much cooling area, than more compact shape. Plus automaticly will make less rpm and more torque.
     
  16. Aug 21, 2019 #16

    Speedboat100

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    Yes I agree...secret lies there...maybe a hole in the middle ? Hollow shaft ?

    https://en.wikipedia.org/wiki/Tesla_(unit)
     
  17. Aug 21, 2019 #17

    Hephaestus

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    caplus.png
    These are what massive induction motors that generate massive heat look like. First you get cooling fins, then you get fans to direct flow appropriately, then you get into water cooling.

    The technology is already out there - we use it daily on industrial sites. Simply a matter of assessing the needs then addressing cooling in a step by step methodology.
     
  18. Aug 21, 2019 #18

    stanislavz

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    Not only.. I do like to imagine pancake motor (inrunner or outrunner) - as a set slices of original stator, cuteed and joined one to one, forming better cooling area and higher leverage. So - square motor, cutted into 4 slices, and joined end to end, will have 4 time torque, and 4 time less rpm. And (if we only take side cooling area into calculation) and 4 times of cooling area :) But some extra copper in coils. All else - magnets/core are in same size mass
     
  19. Aug 21, 2019 #19

    Speedboat100

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    Hollow shaft could bring cooling air to the batteries.

    Then the prop ( and spinner ) should be a integral part of the rotator...and the stator is belted where the spinner starts in a regular plane....with a gaping hole in the middle to bring smoothly air to the batteries. This saves about 1.5 meters in the length. Or ½ meter in a smaller AC.
     
    Last edited: Aug 21, 2019
  20. Aug 21, 2019 #20

    Speedboat100

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    This may be too far in the future:
     

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