roll shake

Discussion in 'Radian' started by JY Air, Oct 17, 2012.

  1. Philip Ellerbroek

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    Mike,

    Did you come to a final fix after this thread progressed?

    Also, how have the blue o-rings been for you? Did you do the modification where you used the 1/4" ID grommets? If so, did it help? I just did the grommet mod and need to fly tomorrow. I was hoping to know if it is worthwhile to get the blue o-rings. I am in AZ and the temps are 60deg when flying. I know Tabb said temp can factor on if you should change the color of o-rings.

    Phil
     
  2. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    Hi Jim:
    IMHO your hypothesis is correct. The additional mass of the LiPo will alter the resonant frequency of the copter and it could well be that, in so doing, it will not longer vibrate when subjected to the same input frequencies.

    It's called mass damping, I believe. http://en.wikipedia.org/wiki/Tuned_mass_damper

    Andy.
     
  3. MIke Magee

    MIke Magee Active Member

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    Hi Philip. I've been grounded for more than a week with flu and weather up here in New England. I plan to have some results (hopefully positive) to share by week's end.
    -m

     
  4. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    It's not 'flu, Mike. It's a "viral upgrade." :)
    Andy.
     
  5. Bryan Harvey

    Bryan Harvey Member

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    I'm chasing ghosts also... Anybody care to take a look at my video and tell me what you see? I don't have enough experience to know what I'm looking at. Is the frame vibrating or just the gimbal? Prop vibrations, gimbal oscillations? You can see shortly after takeoff when I turn on the Radians.
    Gimbal and frame were balanced according to freefly videos and suggestions found on this forum. Hanging gimbal from center point appears perfectly balanced. Camera was balanced on the gimbal with belts off.
    Belts are tight with 2-3mm travel.
    Radians are set within the range of Andy's recommendations for the 5d Mark II.

    I was on 14" APC props for this video but had similar results with the 12" APC's.

    Is this the part where I repeat all the steps above? ;0)


    Also, if I power up my gimbal sometimes one (or some) of the Radians has a high pitched variable buzz sound while just sitting there on the table. Is that normal?

    I also have a clicking sound at startup before the props get up to flying speed. My friend who is an RC guy said it could be coming from the ESC's? Any thoughts?

    thanks...
     
  6. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    Hi Bryan:
    It's a little hard to see what's going on with the gimbal -- were you running the payload camera by chance? Usually that video tells us more about what the gimbal is actually doing -- although it is useful to get a sense of what's happening with the video you show.

    Have you balanced all the props? I'm not saying that's the problem -- it's just that you didn't mention that you had.

    By the way, bonus points to whomever was driving in during your test flight....they kept their cool. "Oh, yeah, it's just a giant black insect hovering above our house... happens all the time, doesn't it?" :)

    Andy.
     
  7. Philip Ellerbroek

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    Brad,

    This seems like a great mod, particularly if you are flying a Canon Mark3 or Nikon D800 and heavier.

    http://forum.freeflysystems.com/ind...-between-cs6-and-3-axis-gimbal.135/#post-8156

    I know Tabb mentioned an upcoming plate, but here are some good items if looking to do this modification in Carbon Fiber. Rockwest Composites has a 1' by 1' 2.5mm thick square for $25 (you can get it in 5mm thickness too, but that is $50 for the plate and may be overkill). Also, they have carbon fiber Loctite in 3ml for a clearance price of $4.88. So for under $35 you can do this square backer enhancement for increased strength but in carbon fiber.

    TIP: You MAY want to rethink countersinking the carbon fiber plate as it may risk the plate to cracking. Perhaps stick to a simple drill hole if possible.

    Here are the links for the products:

    1'x1' 2.5 mm Plate:
    http://www.rockwestcomposites.com/browse/carbon-fiber-plate

    48111
    1' x 1' x 0.100" / 8 ply (0,15,-15,0)s
    Uni
    Peel Ply (Satin)
    0.1
    1 to 5
    $24.99
    6 to 10
    $19.79
    11 to 999
    $17.59


    Adhesive:
    http://www.rockwestcomposites.com/browse/clearance-products
    1021-3-Clearance
    Loctite 330 Depend - 3 ml kit
    Kit
    Pale Yellow
    2.0
    3.0
    1.0
    0.3
    6.0
    1 to 5
    $4.88
    6 to 10
    $7.50


    Phil
     
  8. MIke Magee

    MIke Magee Active Member

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    I did a vibration analysis on the motors ( See below ). I have swapped out 3 of the motors (8, 7 & 5) to calm them down, and added some blue rings.

    But alas, the problem remains. Despite all the things that we have done from re-re-re-balancing, motor swaps, gimbal tweeks, bands, bobbles and several sacrificial chickens. SO, I have given up. I'm placing my beloved Cinestar, 360 gimbal, radians, transmitters and all the stuff into 2 pelican body bags and shipping them to Columbia falls. I've simply lost too much opportunity with this vibration and wasted WAY too many hours. I will share what they find, and should know in a couple weeks.

    BTW, vibration analysis below was done at setting "100" in the motor test, with a 5 second sample. The "bad" motor below was a 10 second sample going from motor speed 0 to 100.

    Thanks to everyone who suggested things to try from Andy to Casey.

    vibration analysis.jpg vibration analysis2.jpg
     
  9. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    It was those damned chickens, wasn't it Mike?
    Use goats. They work better. :)

    Seriously -- bummer.

    I appreciate you posting the vibration shots. They're quite telling in terms of "good" and "bad" motors, aren't they?
    Are you going to change the bearings on the bad motors?

    Andy.
     
  10. Gary Haynes

    Gary Haynes Administrator
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    Mike great series of screen shots. Can I ask you to describe how you mounted and the orientation of your iPhone on the boom?
     
  11. Philip Ellerbroek

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    Mike,

    What IPHONE App is that?

    Phil
     
  12. Gary Haynes

    Gary Haynes Administrator
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    Vibration from Diffraction Limited Design
     
  13. Pavlos Antoniou

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    Woooo these numbers are too low...!

    What motors are these... have you hanged the copter in order to measure the vibes???

    I cannot even think of these numbers on new motors too ! :( :(
     
  14. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    Pavlos:
    Could you clarify what you mean by "these numbers are too low?" Do you mean the MK Tool Motor Test setting or some of the vibration data?

    Thanks
    Andy
     
  15. MIke Magee

    MIke Magee Active Member

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  16. MIke Magee

    MIke Magee Active Member

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    Gary, I'm tragically simple. I use what I have. The parts I used for mounting are as follows:

    parts.jpg
    4 of: standard boom knuckles, 35mm bolts, press nuts. One rubber band, and a 3D level. Also note that there is a 1'X1' 1/4" foam pad that I rested the whole thing on. All booms extended over the foam and no boom touched any surface at any time.

    The mounting I used was placed back towards the end of the boom. The iPhone was leveled and held in place very tightly with the band. It was very secure, and took about 2 minutes per boom to install and uninstall.

    mounting.jpg

    Here's what it looked like - a hack, but my best one of the week. Of course I didn't leave the level or prop on it. It's interesting to note that each analysis identified my button press to record on the Y axis. Also, before I ran each one, I ran it w/o the motors and made sure they all flatlined. I could have avoided that bump with a delay start.

    My whole goal was not to analyze the performance of the standard QC motor, but only to compare them against each other.

    Best,m

     

    Attached Files:

  17. MIke Magee

    MIke Magee Active Member

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    Andy, they were fresh out of goats at Sacrifice Depot. Besides after paying the absurd transport charges for these pelicans, I'll be eating goats and small animals for the next 6 months.

    And yes, vibrations, like sound (redundant) hides nothing. I'm game for changing the bearings if QC won't RMA the motors, and someone can point me in the direction of parts and process.

    -m

     
  18. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    That's the trouble with that place. They keep their stock levels soooo low that there's never enough of what you want when you need that special something...

    As luck would have it: http://forum.freeflysystems.com/ind...he-bearings-on-a-qc-3328-motor.563/#post-8201


    Andy.
     
  19. MIke Magee

    MIke Magee Active Member

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  20. Pavlos Antoniou

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    MIke i am talking about the Vibration numbers... they are too low..! how was the MR?? it was hanged??? or what??
     

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