ALTA altitude drop in forward flight

Discussion in 'ALTA' started by Rory Hinds, Sep 22, 2015.

  1. Rory Hinds

    Rory Hinds Member

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    I’ve been flying my ALTA and noticed a significant altitude drop in forward flight in both Height and Position flight modes, manual mode seems find but they you ride the throttle anyways.

    The strange thing is flying backwards is dead on and so is left to right but on forward flight it drops a huge amount.

    I can have the ALTA at 8 feet off the ground and when I fly forward 20 feet it would drop 5 feet and be 3 feet off the ground, its pretty crazy.

    AUW= 30lbs
    Payload= Red + M15
    Power = 2 x 10,000mah
     
  2. Chris Jordan

    Chris Jordan Member

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    I bet it wouldn't happen if you weren't maxed out. What's your location? (Where do you live)
     
  3. Rory Hinds

    Rory Hinds Member

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    I'm Fernie, BC Canada.

    As mentioned its fine flying backwards and left to right but forward flight has the drop, so how could this be weight related?
     
  4. Chris Jordan

    Chris Jordan Member

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    Your CG could be off, and you're WAY over AUW. Did you happen to read the manual? here's the link in case you didn't yet. http://freeflysystems.com/software-manuals You totally should. Grab a drink, get comfy and highlight those gorgeous 128 pages. For reference though, here's the Guide on AUW. Don't fly again with that much weight IMO: Gross Weight .png
     
  5. Rory Hinds

    Rory Hinds Member

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    Thanks Chris, yes I've read the manual. Thanks.

    I'm sure this is not weight related as it flies fine backwards and side to side so don't see how its only in forward flight that the weight effects it like this.
     
  6. Chris Jordan

    Chris Jordan Member

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    It's choking. You're AUW should be set to 3300 ft and your current temp. You're a good 5 lbs OVER the Max.
     
  7. Rory Hinds

    Rory Hinds Member

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    I don't find it choking at all. Motors are a cool 34C after flying for almost 60minutes (7 x 8.50 minute flights)

    If it was the weight then the motors would be stressed and at a higher temp plus I'd see this drop in altitude on backwards, left and right flight not just on forward flight.

    If the altitude issue was on all flight then I'd be with your thinking but as its not and the motors are cool cucumbers then this is something else... bug in the accelerometer... the whole forward only drop is just weird.
     
  8. Josh Lambeth

    Josh Lambeth Well-Known Member

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    Sounds like you need to adjust the Height Gain settings a bit. Mine also drops a touch and I am at 25lbs AUW. I need to tune a bit more.

    What is your Height Stiffness setting?
     
  9. Rory Hinds

    Rory Hinds Member

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    My height vertical stiffness is 13
    And my position gains for horizontal stiffness is 30
     
  10. Tabb Firchau

    Tabb Firchau Administrator
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    Drooping in height hold mode to some degree is inevitable. It comes from the barometer being affected by the props and air inflow / outflow from the enclosure over the electronics.

    It can also be worse lower to the ground with more air disturbance. If you can run a higher height stiffness it should get better, but watch out for any vertical oscillation.
     
  11. Rory Hinds

    Rory Hinds Member

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    does the air flow differently in reverse when you fly backwards compared to flying forward?
    I'm getting very noticeable altitude holds going backwards, its solid and reliable but going forwards it drops a major amount so much so that forward flight less then 8 feet off the ground is dangerous. I can do the same shot in reverse which is just strange.

    Here are my Height settings...

    [​IMG]
     
  12. Rolf Ableiter

    Rolf Ableiter Active Member

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    it makes a difference because the barometer needs a little hole for measuring. This should be in the front.
    the faster you fly the more you'll loose height.
    you'll have the same behaviour with MK, WKM, A2, inspire 1, whatever.
    the inspire is better because it is a closed system and perfectly balanced with the perfect settings.
    but even the inspire looses height when flying fast forward.

    the only way to have a stable flight is to have an algorithm wich compensates the drift (not only the drift of the barometer, also accelerometer, compass, etc)
    freefly let the user change so much parameters to find the perfect settings and this is really amazing but needs to learn about them and how they interact with each other...
     
  13. Rory Hinds

    Rory Hinds Member

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    totally get losing a little height is normal but what I'm getting is so not normal as it shouldn't be loosing so much height so quickly to make it unsafe to fly forward when you're 8 foot off the ground. It would mean the shots I can get are no longer available with the ALTA which I find hard to believe.
     
  14. Rolf Ableiter

    Rolf Ableiter Active Member

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    how fast do you fly?
    8 feet is not very high in my opinion when flying fast.

    I'll get mine tomorrow and i will try it out. The problem could be that i find the same behaviour normal and you not. It would be good to see a mvieclip of your Alta flying with the heightdrop...
    Did you try it with different payloads? and did you try it with another system (like a cinestar with wkm, MK or similar)?
     
  15. Rory Hinds

    Rory Hinds Member

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    yeah totally. My normal and your normal could be completely different.

    I'll try shoot some footage of the drop and post it.
     
  16. Gary Haynes

    Gary Haynes Administrator
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    Rory the vertical stiffness of 13 is below the default setting of 20. Try bumping that back up to 20 and see if it doesn't improve.
     
  17. Josh Lambeth

    Josh Lambeth Well-Known Member

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    Gary the SB sent out said to drop it to 12... I have had Alt. Hold issues at 12 and will be trying 15-18 to see how it works...

    Josh
     
  18. Gary Haynes

    Gary Haynes Administrator
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    Forgot about the SB. Need an update to the manual ;)
     

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