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Prop Change

Posted by David Ardis on November 28, 2013 at 2:30pm

I have just purchased 4 new Graupner 10x5 Propellers to replace the existing APC 10x4.5 slow fly props on my TBS Style Quad as I was not happy with the vibration levels.
Thought I would share the results.

3689560737?profile=originalVibration levels for APC Props

3689560794?profile=originalVibration levels for Graupner Props

I had spent a lot of time trying to balance the APC props but could never get much improvement. I just balanced Graupner props very quickly and got the above result

David Ardis

Tags: apc, balance, graupner, propeller, vibration
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Comments

  • David Ardis December 10, 2013 at 4:43am

    Leonard

    Had the quad out at the weekend and got the pitch and roll P up from 0.14 to 0.18 and as you have said altitude hold is much the same.

    The quad still needs some fine tuning but even on a windy day it is very stable any easy to fly.

    Thanks for everyones comments

  • Developer
    leonardthall December 9, 2013 at 6:39pm

    Hi David,

    Sorry for the delay. Here are the results of my analysis. The is the standard deviation after subtracting a 5 sample moving average filter from the data to account for real flight accelerations.

    Graupner

    X Noise: 0.23909
    Y Noise: 0.14196
    Z Noise: 0.52456

    APC

    X Noise: 0.46539
    Y Noise: 0.31099
    Z Noise: 0.53945

    So it looks like the Graupner are better in the X and Y but have similar performance in the Z. So your position hold should be better but your altitude hold should be about the same.

    Thanks for providing the files and sorry for the delay in my reply!!

  • David Ardis December 1, 2013 at 4:59am

    Leonard

    You can download the the files from the link below.

    If you want me to do any other test send me a PM

    Graupner Props

    APC Props

  • Developer
    leonardthall December 1, 2013 at 3:10am

    Hey David,

    Could you post the two logs you used here. I would like to run them through my matlab code to put numbers to the pictures you have above.

    Thanks!

  • Gary McCray November 29, 2013 at 12:43pm

    Hi Oliver and Robert,

    Actually one of the more interesting points is how the multicopters are used, if as Oliver said, <10mph.

    Then most of the dynamic motion based characteristics aren't as important.

    What you want are propellers that will permit stable vibration free hover and appropriate response for necessary maneuvering. And high efficiency is important too.

    If you want speed then the situation gets a lot more complex.

    But I would say that the veruy large majority of actual uses for these things do not require speed and the majority of high performance options are pretty much hobby fun only so not critical for "pro" uses.

    Basically for the significant and professional use, speed is not an issue, optimized hover and precise handling and payload carrying and stable (and vibration free) camera platform capability are what are important.

    So basically I think the complexities of high speed prop design for multicopters can be deemphasized.

    What we really need are propellers designed for our actual multicopter applications, various sizes and weights of copters with stable camera platform operation in hover and slow speeds.

    Also increasing propeller diameter increases efficiency but introduces more asymmetric forces acting around the prop shaft (vibration or tilt). So that is always a trade off.

    All that said, except for Paul Pounds, it doesn't seem like anybody has done any serious design of rigid propellers designed to hold a vehicle primarily stationary in a hover and we are just using airplane castoffs.

  • Rob_Lefebvre November 29, 2013 at 8:53am

    Yep, that's what the dampers are for.  Some head designs now feature a firmer pivot point in the center of the head, allowing even softer dampers to be use.  Align has a sleeve with tapered bore which fits between the dampers.  Gaui has the "Formula" head, which actually has the feathering shaft retained by a central ball bearing system.

  • Rob_Lefebvre November 29, 2013 at 8:04am

    Oliver, lead/lag is a different thing.  Blade flapping really is up and down, and is taken care of by either the teetering hinge at the center of the head, or the flapping hinges at the root of the blade.  Flapping and Lead/Lag do get intermingled in some weird ways that I haven't actually understood yet.  It makes a difference if the lead/lag hinge is inboard or outboard of the flapping hinge.  

    In forward flight, the entire rotor disk actually tilts over, this is due to the flapping to relieve disymmetry of lift.

  • MR60
    Hugues November 29, 2013 at 8:01am
    Having tested different brands of props at different sizes&pitch, the conclusion was you can't draw a general conclusion on a brand better than another. In the same brand some prop size are really good while other sizes are really bad (in terms of vibrations).
    Personally the best i have experienced in 14-15" size are the wood XOAR props because they are very light, rigid and produce two times less vibrations than the APC of the same size.
  • Rob_Lefebvre November 29, 2013 at 3:46am

    Yeah, it's a miracle these the APC SF props work as well as they do. And indication that APC is a high quality product that is overdesigned.  I've been using them on a medium-lift octo with a fair amount of power.  But I'm switching over to APC MR's.

  • Developer
    John Arne Birkeland November 29, 2013 at 3:34am

    Slow fly propellers where never meant for this. They are made for low rpm's on light weight planes, not high rpm lifting like we are doing.

This reply was deleted.