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3-Blade Props

Discussion in 'Phantom 2 Discussion' started by Prophecies, Mar 11, 2015.

  1. Prophecies

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    Hi,
    So I have a few questions regarding the use of 3-blade props on my phantom 2. I recall watching a video and reading some articles about different prop types (Stock, carbon fiber, tri-blade, etc). Here is my question. I will be using my phantom 2 to film a friends wedding this summer, and it seems like 3-blade props are noticeable quieter than the stock DJI props. If I can reduce the amount of noise my Phantom will make during a wedding event, it would be fantastic.

    Does anyone have experience using these? Are they actually much quieter?
    Here is the video where I first heard about the three-blade props:
    https://www.youtube.com/watch?v=t6z04r2OZtE

    Thanks!
     
  2. QYV

    QYV

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    oh man if there are quieter props I'm going to have to try them! but

    that video was for a P1 but he described a 20% drop in flight time in the 3-blade.

    now I have to test this myself lol

    edit: found another video where he tests these props, he talks about them working the motors much harder than normal
    https://www.youtube.com/watch?v=R-vhQDsnoKA
     
  3. Prophecies

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    Yep, drop in flight time, but that is not really a problem nor a concern of mine. If I can diminish the loudness by a significant amount, I'll do it.
     
  4. QYV

    QYV

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    yea me either I'm way less concerned with flight time than motor stress
     
  5. Prophecies

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    The reduced noise is related to motor stress? I was more under the impression that the same force/thrust is distributed between three blades instead of two, which in turn reduces the vibrations in the air causing the sound it makes. I could be wrong though.
     
  6. QYV

    QYV

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    I'm not a physicist or anything but I feel like this is an educated statement:
    The reduced SOUND is as you describe, more blades = less sound due to the movement of the air
    The engine heat/stress would be due to the engines having to work harder to push 3 blades through the air, rather than 2.

    so related? yes but not like, directly. correlated

    I went ahead and ordered what appear to be some new fixed-blade 3-leaf plastic (not the carbon fiber collapsible) props from china that won't be here for a month. pricey, but they all are
    http://www.amazon.com/gp/product/B00UERYNS4
     
  7. N017RW

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    This is an condensed excerpt from an aircraft propeller manufacturer's FAQ:

    "Yes, in most installations increasing the number of blades helps to reduce noise... Vibrations are also perceived as noise... A 2-blade propeller produces two pressure pulses per revolution, where a 3-blade propeller will produce three smaller pulses per revolution (for the same amount of total thrust) which is inherently smoother and therefore quieter. The 3-blade propeller will generally have a smaller diameter than the 2-blade propeller that it replaces, which also reduces the tip speed and noise... The reduced diameter of the 3- blade propeller will result in less tip-generated noise and a greater clearance between the blade tip and the ground or fuselage. Both of these characteristics will reduce noise."

    All things being equal, more blades=less efficiency.

    But they do look cool!

    Lets us know how it works out.
     
  8. QYV

    QYV

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    cool... I think we're saying the same thing yes? the next logical step is less efficiency = motors work harder hence more stress on them, heat, whatever

    hehe they do look cool but I'm actually way more interested in noise reduction... I can't fly in public without drawing a huge crowd and I don't know about you guys but even in the city I can noticeably hear the Phantom buzzing up to at least 80m or more. Looking forward to being able to fly lower and not draw so much attention. in 6 weeks :roll:
     
  9. FedeVision

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    I'm testing cheap 9450 plastic selflock triblades (ebay), 17 grs eo, got to balance them a lot on Dubro, sounds like they spin faster on take off, once on air hard to control, hand catch or land (really needs gains adjustments), quieter but with a fffffffffff sound, faster batterie drainers, higher frecuency vibrations, less low frecuency, when descending tends to VRS a lot, maybe more twiching on gains could help, but Im waiting for 9050 GWS version to arrive so I can compare quality and behavior.

    Edit: forgot to mention this triblades are soft like stock 9443 blades.

    HTH
     
  10. gword256

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    I am also interested in the outcome of these three blade props. A quieter ride would be nice.
     
  11. QYV

    QYV

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    you got the ones like these? I didn't think of Ebay, just snagged them from Amazon
    http://www.amazon.com/gp/product/B00UERYNS4
     
  12. FedeVision

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    Yeap, those look the same, but description says: 28 grs!? Maybe type error there
    The ones I have are 16-17 grs each
     
  13. QYV

    QYV

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    his "item" is for 1 pair: 1 CW + 1 CCW so I was thinking the 28g was for the item total, ie the pair (~14g each)
     
  14. FedeVision

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  15. N017RW

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    It looks like they're just a third blade added to the hub.

    These are not designed with any consideration to the aerodynamics.

    I true three blade equivalent replacement would have reduced pitch and lenght per blade (reduced disc diameter).

    More blades = less efficient. More blades = less disc diameter. Effective when required for added prop to ground or fuselage clearance.
     
  16. jumanoc

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    Are your propellers balanced ? Difficult to control may be caused by unbalanced units.
     
  17. QYV

    QYV

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    do you feel like those CF triblade props ARE designed with those considerations? and these aren't ?
     
  18. SteveMann

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    The basic gains may be too high with the three-bladed prop.
     
  19. N017RW

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    You know I have not personally seen, held, or used any other props.
    The video FedeVision showed is my only glimpse.

    If they are nothing more than some guy making a mold with 3 blades from the two blade design than FV's review of the performance comparison does not surprise me.

    Because of the added weight and drag it takes more time and energy to change RPM (dampening) thus increasing the response time of corrections made by the FC. This causes the instability.

    I learned similar lessons with fixed wing a/c and prop testing.
    More [blades] is not better for more's sake.
    Three+ bladed props are used as a necessity not because of their looks.

    Now the tri-9050's he's waiting for may be an improvement and more comparable to twin 9450s as that will reduce the disc size by about .8"
     
  20. FedeVision

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    Sure, all balanced, first thing I did when received.