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

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

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  1. Sep 13, 2019 #301

    henryk

    henryk

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    =KASPERwings have STATIC stability and controll,
    i.e. it can "fly" with ZERO forvard speed !

     
  2. Sep 13, 2019 #302

    stanislavz

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    Last edited: Sep 13, 2019
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  3. Sep 13, 2019 #303

    Speedboat100

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    Yes the wing tip brakes seem a bit odd...and might be a menace to a beginner.
     
  4. Sep 13, 2019 #304

    Speedboat100

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  5. Sep 13, 2019 #305

    Speedboat100

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    Last edited: Sep 13, 2019
  6. Sep 13, 2019 #306

    Aerowerx

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    http://airfoiltools.com/
     
  7. Sep 13, 2019 #307

    Speedboat100

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  8. Sep 13, 2019 #308

    stanislavz

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  9. Sep 13, 2019 #309

    stanislavz

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    I will try to get in touch with them, they are using carbon rods tech, from Jim.

    But - twin boom configuration has beauty in placing wheels on boom, safer prop (there was incidents then prop have not deployed in time). Easier to make and smaller molds - especially, with improved untapered wing by Strojnik .. Almost same as building two gliders in place of one.

    Ps. my idea of using same airfoil for tail was wrong, and no one fixed it.. :)

    Will try to play with moldless wings, i do have cnc foam cutter..

    And post me to gallery of composite wing/ wingtips connectors..
     
  10. Sep 13, 2019 #310

    Aerowerx

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  11. Sep 14, 2019 #311

    Speedboat100

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  12. Sep 14, 2019 #312

    Speedboat100

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    I was wandering if a 14,2 m ( max 3 seater ) spanning all electric flying wing could have a FBW system...and an autopilot...it might give more customers.
     
  13. Sep 14, 2019 #313

    Speedboat100

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    This ought to fly 1 hr at 10 kg/m2 wing loading. It has Eppler 548 ....a 0 moment foil.
     

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    Last edited: Sep 14, 2019
  14. Sep 14, 2019 #314

    Speedboat100

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    How about electrifying Pelican ?
     

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  15. Sep 14, 2019 #315

    stanislavz

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    Me not. Have to nice childs.

    To narrow cg range, to tricky to fly...
     
  16. Sep 14, 2019 #316

    Speedboat100

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    PIOS tendency increased ?
     

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  17. Sep 14, 2019 #317

    Aerowerx

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    A zero moment isn't essential. In fact you can use just about any airfoil, but low moment is highly beneficial. You are going to need some kind of nonlinear twist to ensure that the stall starts at about 30-40% of the half span. The AoA will then automatically adjust itself for zero moment.
    (A bit more complex than that, but want to avoid thread drift again)
     
  18. Sep 14, 2019 #318

    Speedboat100

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    I was thinking about twisting just the end piece of the wing..last 20%.
     
  19. Sep 14, 2019 #319

    Aerowerx

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    You should have the largest amount of twist at 30-40% of the half-span. That is where the stall will start, leaving the ailerons still effective.

    Look up Al Bowers paper on the PRANDTL-D. Why reinvent the wheel---I mean wing:)? He has already figured it out! The important thing is the general shape of the twist distribution, not the absolute amount of twist.
     
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  20. Sep 14, 2019 #320

    Aerowerx

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    Out of curiosity, I was just looking at some 20kw-30kw motors.

    Have any of you considered that they use liquid cooling? At least the ones I have looked at. That means a radiator, pump, and coolant, which in turn means more weight.

    Another thought. If you use "5 gallon size" battery pack that weighs about 100 pounds, you can distribute the batteries to get the desired mass distribution. The motors I was looking at weight about 35 pounds, without cooling system. This is one advantage over a 95 pound IC motor, and you don't have to worry about the CG changing as the batteries are drained.
     

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