ALTA is not stable in wind...

Discussion in 'ALTA' started by Josh Lambeth, Sep 16, 2015.

  1. Josh Lambeth

    Josh Lambeth Well-Known Member

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    Hey Guys,
    I'm curious how many of you have flown your ALTAs in the wind. I'm talking 10+ mph winds. Our ALTA even after messing with the gains doesn't fly well at all with our 1DC on board. We are 25lbs AUW with batteries. It seems like it wants to go very unstable if I am flying it around. A couple times I needed to let off the stick and let it fly with the wind a bit before it would settle down. I was actually worried it could crash with how unstable it was flying. My current gains in Attitude Mode are Stiffness: 58 and Hold: 56. I've tried hold gains as low as 43 and as high as 60. Stiffness gains have been all over the place as well but I can't seem to find anything that works.

    I am now using the black vibration dampers and that seemed to help a small amount compared to the teal ones.

    Altitude hold works ok at a setting of 12. Not awesome but that's to be expected in the wind.

    Position hold is completely unusable in the wind. I haven't tried adjusting any of those settings yet however.

    Any help would be awesome. Thanks.

    Josh

    P.S. I did speak with the Copter Kids and they suggested trying a "overall gain of 65" but I am not sure if that is the Stiffness or Hold setting. I tried to clarify with them bUT haven't received a response yet.
     
  2. Tabb Firchau

    Tabb Firchau Administrator
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    Go back to default stiffness and hold strength Josh and make sure you dont have any vibration issues.
     
  3. Josh Lambeth

    Josh Lambeth Well-Known Member

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    I will try that.

    Looking at the App I see there is a vibration data coming in through the monitor. What is an acceptable number there? I remember seeing that earlier and I believe I was seeing between a 10-14 on all the motors.

    Thanks.

    Josh
     
  4. Chris Jordan

    Chris Jordan Member

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    Josh, The Alta should be VERY stable for you in high wind, Echoing Tabb's comment, start over at default settings. If you're worried, use weight first instead of your camera and gimbal. Cheers
    CJ
     
  5. Cody Hanthorn

    Cody Hanthorn Member

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    Any update on this Josh?

    I have a little concern on this "I was actually worried it could crash with how unstable it was flying". If your gains where on the low end and then on the high end without a visible change that makes me a little worried.

    Playing with all kinds of vibration dampeners seems painful and lots of experimentation. Are there known recipes that work?


    -Cody
     
  6. Josh Lambeth

    Josh Lambeth Well-Known Member

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    I have been traveling and just got back. I haven't had a chance to try any new settings. Going to tomorrow hopefully.

    Josh
     
  7. Tabb Firchau

    Tabb Firchau Administrator
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    I am flying default settings in very windy conditions. The ALTA does get hit by winds because of the huge props we run and relatively light disk loading, but I dont find it uncontrollable.

    Hoping the default settings give you a better feel Josh
     
  8. Josh Lambeth

    Josh Lambeth Well-Known Member

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    Thanks Tabb. I'll give it a try. Been super busy with other jobs lately (not flying unfortunately but will give it a try soon).

    Josh
     
  9. Aj White

    Aj White Member

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    I have a theory, I have been flying a bunch in the last week in all kinds of conditions and noticed on descent in height mode it's really unstable. however when I fly in purely Manual it descends much smoother. Anyone else experience this?
     
  10. matt ragan

    matt ragan New Member

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    Were you able to do some testing with the default mode? My Alta is also flying somewhat eratic in the winds
     
  11. Dave King

    Dave King Well-Known Member

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    Interesting to know about this. Can anyone tell me what the acceptable vibration numbers you should be seeing in the app are?
     
  12. Josh Lambeth

    Josh Lambeth Well-Known Member

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    I've flown in winds 5-8mph and it was flying better then before but it still seems a little wobbly... I am on full default settings which were from the factory after the recall.
     
  13. Fabien Deregel

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    Hi, if ou are flying with the Movi gimbal, you can make maybe a quick test : put the gimbal in " motor kill" mode and check if you notice any difference in the behavior of the Alta during flight.
    Sometimes, it happens that gains seem to be well setup on the ground / handheld on the gimbal but not adapted to flight at all. With just tiny too high gains, the gimbal will get in a kind of auto oscillation , which is routed by the dampers and make the frames "bump", then people think that the flight controller is the culprit or the machine itself when it's simply... trying to correct a parasite wobbling coming right from the gimbal itself...
    It's a bit out of subject, but check in the video below what happens on a DJI frame .... it's needs to reduce dangerously the gains of the flight controller and the culprit here is .. the gimbal ( and also the DJI frames that are wrongly designed but that's another story... )
    check the booms at 15 second in the video... With a well tuned Movi M5, there are no more oscillations at all on the same machine and flight controller gains can be risen up to 30 points more with no issues and bring the flight much more comfortable...
    Hope this helps and that you will find the right settings or the origin of the trouble :)
    Best regards,
    Fabien

     
  14. Michael McVay

    Michael McVay Active Member

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    Hey guys...my Alta was quite unstable in the wind as well. Here are my conditions and what I was hoping for:

    1. Alta was set to stock settings after being returned from the wiring upgrade
    2. Flies fantastic in manual mode.
    3. When in position hold in wind (I was testing in 15-25mph) the Alta would hold its position over the ground, but you needed nerves of steel to watch what it was doing to accomplish that. Super twitchy and wobbly - lots of rocking around in the sky.
    4. Lots of height variation but more on that later.

    What I wanted to have is an Alta that can be parked in the wind and remain relatively calm and stable looking. My other copter are all quite good in this respect. I emailed support about my experience and what I was hoping for and was advised to tune the horizontal stiffness and hold strength LOWER. Essentially I think the copter was trying too hard to stay perfectly flat and trying too hard not to move at all. This must have led to all the constant twitching, rocking, etc.

    I started by lowering both settings by 3-5 from their default values. This resulted in the copter being far less twitchy and more softly adjusting itself to stay put. I did not notice any movement in the way it was holding its position over the ground. So I then increased the horizontal stiffness by 1 or 2 so that number ended up getting closer to the default setting. This is where I left it. Horizontal stiffness is maybe 2 clicks below default and hold strength is 3-5 lower.

    Now, I was testing with the lower tray on the bottom with 6 pounds of batteries for dummy weight. This is 2-3 pounds lighter that how I generally fly it. I am sure that will have some effect on things. Also, at the suggestion of Dave King I am going to hang the Alta by the middle of the center handle and double check overall balance. He said that to get perfect balance he had to shift his batteries slightly.

    I'm sure I will make a few more small adjustments as I put the M5 back under it and fly at my regular weight. But, lowering those couple settings really helped get my machine to a position that made me feel good about watching it sit there in 20+ mph winds and varying gusts.

    Important: Remember that these adjustments are in the Position tab once you have selected Aircraft Dynamics. It is also recommended that you adjust these settings only AFTER your machine flys the way you prefer it to fly in manual mode. My assumption is that these settings are also factoring in the way you fly in manual mode - and use their values to get your position hold characteristics to match your manual flying characteristics (but I'm not 100% thats why they recommend the tuning sequence that they do).

    Hope this helps point you in the right direction.
     
    Matt Beardsley and Steve Maller like this.
  15. Gary Haynes

    Gary Haynes Administrator
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    Good point from Michaels post. Small changes are the ticket to tuning. And then test. Happy with result make a note for the future similar situation. Not happy make another small change. Really no different that the tuning that we used to do with MK. If you find the numbers are getting high go back to default. Also try to change one parameter at a time. Makes tuning much easier. Couple at a time, maybe. More than that you may never know what is causing your results to be good or bad.

    Read pages 60-62 in the Rev C manual.
     

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