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CF props vibrating

Discussion in 'Pro/Adv Discussion' started by exit 4, Mar 1, 2016.

  1. exit 4

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    I noticed today as I was preparing to take off that my P3A was vibrating on the ground before take off. It was sitting there as the props were spinning waiting for me to push the throttle. The whole craft was shaking. I know the props are balanced as I did it a few weeks ago. I replaced them with the regular white plastic type. Could the cf props be out of balance with nothing happening to them other than flying? I am going to rebalance them tomorrow to double check. Any thoughts?
     
  2. 0DRK3RT

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    Did you recently update your FW? Did the vibrations not happen when you put the white props back on?
     
  3. exit 4

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    White props and no vibration. I don't understand how they could go out of balance without some type of contact or anything like that. The thing is, there was no vibration on the earlier flights. As if something happened during the last flight? Any ideas?
     
  4. ianwood

    ianwood Taco Wrangler
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    Are they DJI props or some other brand?
     
  5. 0DRK3RT

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    I wonder if you screwed one of them on crooked? Just a guess
     
  6. dixter

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    put three of the white props on the quad and one of the CF props... spin it up... if it doesn't vibrate then take one more white prop off and put another CF prop on... if you get to 4 CF props and no vibration then you installed them correctly and they work... if not then you should be able to tell which CF prop is the issue and replace it...
    There is one other issue that people don't seem to think about.... its called Prop Tracking and its mainly caused by one side of a prop being warped... the prop itself will exhibit a perfect balance if the balance is checked but if the two outter edges of the prop don't track each other then the prop will not spin correctly and cause vibrations...
    so.. you might have a warped prop ???
     
  7. exit 4

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    Genuine DJI.
    Just checked the balance today and two are out of balance. How can this happen? No crashes, no falls, no kind of abrasion at all. Can't figure it out.
     
  8. exit 4

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    Interesting, the tracking issue. Never heard of it. Of course there are many things I am nieve to in this realm. Thanks.
     
  9. dixter

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    Thats why I'm a little surprised when I see people say they keep the props mounted when in a carry case for the quad... if there is any pressure on the props and they get warm... say in a car... then they can become warped...
    If you want to test a warped prop then take an old prop and heat it with a hair dryer and bend one end of the prop so that both ends won't track each other...
    then put it on a motor and see how it affects the air flow of that prop... the larger length props ( helicoptor ) are more prone to bad prop tracking than the short span of the quad props... but its still one more item to check for in your investigation... easy to rule out a warped prop...
     
  10. dixter

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    to check prop tracking on our RC helicoptors we put a thin line of white paint just at the tips of the blades... when you spin up the blades you look at them from the side.... you look for the thin white paint line.... if the line looks thick then you know the"prop is not tracking correctly... if the line looks thin the prop is tracking correctly and not warped... on a quad the props are easy to check tracking with a prop balancing jig... just put the prop on the jig... place the jig on a counter top with the prop extending over the edge of the counter top... move the jig with one edge of the prop hanging straight down and the prop edge as close to the side of the counter top without touching... now while watching the prop from the side rotate the prop until the next prop edge is straight down... the distance from the prop edge to the counter top edge should be exactly the same... if not then you have a warped prop... just one more step to complete when balancing a prop properly...
     
  11. Phantomfreak

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    Lots of good info on prop tracking.. I knew what this was but not the name. I agree about keeping the props on when the bird is in the case.. I do it with my microraptor case but I take the lid inner foam piece out so as to have no contact and pressure on either the props or the RC antenna's.
     
  12. exit 4

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    So, I balanced the CF props again. Put them on the craft. Start it up and no vibration. Idles smooth, moves nice, no sign of vibration. Fly for 6 or 7 long flights. Today the bird is vibrating again. Put the stock white props back on. No vibration again, so I now am using the standard plastic props. Anyone have any idea why the vibration keeps coming back to the CF props? I'm lost as why it would go away and then come back? Help lease.