Pop rivets holding 1.5 mm plywood on 15x10mm spruce longerons . Good idea ?

Discussion in 'Wood Construction' started by Speedboat100, Oct 4, 2019.

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  1. Nov 14, 2019 #61

    Speedboat100

    Speedboat100

    Speedboat100

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    I changed the blue....now the white stripes.
     

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  2. Nov 14, 2019 #62

    proppastie

    proppastie

    proppastie

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    deep state :eek:
     
  3. Nov 16, 2019 #63

    Speedboat100

    Speedboat100

    Speedboat100

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    I have no clue why the link did not work.
     

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  4. Nov 25, 2019 #64

    lr27

    lr27

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    With rivets, at least you know just where the parts will break.
     
  5. Nov 25, 2019 #65

    lr27

    lr27

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    Curious how you propose to break Betz's limit. Seems unlikely.

    If this fairing is as high as the blades of your VAWT, better make sure it CAN'T get loose, or someday when the wind is really tearing along, and your turbine is at high rpm's, it will hit a blade. You may get some interesting interactions between the direction of the fairing and the pulsed changes in wind direction from the passing of the blades. I think this would also be a problem with HAWT's, and a quick internet search indicated there's been some research on this. OTOH, the fairing might mean a bit less periodic stress on the blades, since they'd be passing through a smaller wake from the tower. I suppose if your blades are the spiral type, their wake wouldn't beat up on the fairing all that badly.
     
  6. Nov 25, 2019 #66

    Speedboat100

    Speedboat100

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    I only hope to brake the Betz's limit as it has been already in 1919 derived to show that the present day propellers are obsolete as the highest teorethical value for mechanical efficiency Cp is just 59,6 %.

    There are about dozen CFD analyses done that show that H-Darreius type wind turbine with articulating blades can exceed the 59.6 value even by 12% .

    https://iopscience.iop.org/article/10.1088/1742-6596/753/2/022056/pdf

    Very few people has actually tried to exceed it to show that researchers are right...and have been right since 1978.

    Anyway Paul Lipps has shown that as means of propulsion the propellers are 85% efficient. Numbers tell that they are anything but as harvesting the wind energy.
     
  7. Nov 25, 2019 #67

    proppastie

    proppastie

    proppastie

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    ...so does that make sense?....I guess without spending the time I do not want to spend ......what is an 85% propulsion propeller.....do you actually get trust 85% of the measured HP out-put of the engine?.....and what is the measure of the turbine?.....flat blade drag of the blade vs harvested HP?

    I seem to remember torque x rpm for propulsion....but is that thrust?
     
  8. Nov 26, 2019 #68

    Speedboat100

    Speedboat100

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    Yes Paul Lipps is a wizard ! You got the picture...albeit the language was poor.
     
  9. Nov 26, 2019 #69

    Speedboat100

    Speedboat100

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    There is also epoxy...rivets just ease the building.
     
  10. Dec 1, 2019 #70

    Speedboat100

    Speedboat100

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    I am starting to assemble the wing that I can start testing the system.

    Almost as if it wasn't a wooden thing.

    Kojetaulu18.jpg
     

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