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Listen to your Phantom......it maybe telling you something important

Discussion in 'Phantom 1 Discussion' started by JKDSensei, Sep 15, 2015.

  1. JKDSensei

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    First of all, I definitely do not claim to be an authority on Phantoms. I'm still learning and have a long way to go before I feel like an "expert". But I've been flying RC for over 40 years and have picked a few fairly good habits over that time.

    Like most people, I have an ever growing library of videos I've captured with various Phantoms and non DJI UAV's.

    Playing back a video I took today, I noticed that I seem to hear more resonance when flying than earlier flights.
    So I went back and pulled up some video from some flights of several months ago and sure enough.....they were much quieter and smoother with no resonance and no jello.

    By listening to the difference in the sound of the Phantom now and then, I can tell that something is changing.
    Now I have to investigate to find out exactly what.

    Another thing that has tipped me to some kind of developing potential problem is that I'm beginning to get Jello in my videos. I did not have ANY jello in my videos until the last 10 flights or so and it seems to be progressing.

    My initial suspicion is either propeller imbalance, motor wear, stress cracks or the controllers aren't controlling the motors as accurately as they used to.

    Propeller imbalance seems the first logical thing to check because that would be the most likely thing to change and easiest to determine. I have used prop guards on this puppy since day one. They all look perfect by the way but I'm going to remove them and do a magnified view to make sure none are developing hidden cracks. Balancing is definitely in order. A prop that develops a crack at the hub could potentially hang in there for a while...but cause some resonance like I'm hearing. Stop flying. Remove props and find out.

    Motor wear: seems unlikely since I only have 40 flights or so on this Phantom. But I'm going to check them for shaft freeplay, vertical shaft movement and any other potential developing problem as best as I can. Perhaps they need a little lubrication. Maybe a bearing has worn. Better to check than lose a bird.

    Stress Cracks: I have used propeller guards on this particular Phantom since day one. I don't see any cracks anywhere in the shell and I've heard that prop guards reinforce the shell under the motors but because of this vibration / resonance I'm going to remove them and examine the shell carefully.

    ESC Controllers: The controller boards control the speed of each motor. While I can't see how a controller board would cause this issue...I'm just keeping it in mind. I don't know of any way to determine if there's any developing issues with a controller board. Well...maybe if one controller board is pushing one motor too fast it could cause a resonance? You tell me.

    I'll post back anything I find but I guess my point is that sometimes problems that eventually bring a Phantom down might be avoided through careful maintenance and paying close attention to the signs that something is changing.

    YMMV

    It would be interesting to hear if some of you guys have experienced these kinds of changes and if you took action or if you ignored it and subsequently had a crash or other issues.
     
    #1 JKDSensei, Sep 15, 2015
    Last edited: Sep 15, 2015
  2. bobmyers

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    I put on a new set of props this week and the noise dropped significantly. I couldn't believe the difference. I had been flying the ones I took off since I received the Phantom. I had balanced them previously but they may have had gotten out of balance over time. I haven't check the balance on the old props, but I will.

    Unfortunately, the ESC's for the P3 are built into the main board, so an ESC replacement would probably involve replacing the entire board. Looking forward to your observations.
     
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  3. JKDSensei

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    Thanks Bob. Maybe I'll try my spare props.
     
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  4. Pilot_FML

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    IMHO everyone of the possible reasons you note above could (and probably does) contribute to the sound change and increasing jello.

    Unless you don't fly much, normal wear and tear has to degrade performance even in with a good maintenance schedule. Unless you R&R key components on fixed and unwavering schedule (like the airlines do) old age catches up to any aircraft.

    Jello in particular is a tough nut to crack ... and keep cracked. The most unbelievably small change, can subtlety and almost inconceivably bring back large amounts of jello. I know that very well from all the experimenting I've done with trying to suppress jello. Doing so is 80% scientific and 20% a matter of art.
     
  5. JKDSensei

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    ok. Just seems this Phantom is a bit "young" to be developing issues. If I find something obvious that caused it I'll post it.
     
  6. kjar211

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    I just bought new props from dji and it's balanced yet very noisy. Thinking about another brand maybe
     
  7. JKDSensei

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    If you have video saved from your first few flights, go back and play those and listen to the sounds you hear. Is it the same or has the Phantom gotten a lot noisier? If so, it could be resonance vibration from wearing motor bushings or bushings with not quite enough lubrication. If a motor has ANY axial play in the shaft (even if it feels tight), the motor could resonate slightly. I think 3 bladed props might be good.
     
  8. JKDSensei

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    The sound continues to get louder. Almost afraid to fly it. Lubricated all 8 bearings with TRI-FLOW Teflon lubricant and it worked......for all of 3 glorious minutes. Then the resonance came right back.

    Seems that you CAN lubricate the bearings after all. Maybe if I had done it early on the motor would have lasted longer? Not sure. But once a bearing is actually worn, it's not likely to "repair" the damage by lubricating. It may get quieter for a few minutes....and that's exactly what I experienced.