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Phantom can't maintain altitude in GPS Mode

Discussion in 'Phantom 1 Help' started by felas, Oct 13, 2013.

  1. felas

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    Hi all,

    I am new pilot, just a couple months having phantom. Several flight with just gopro and Immersion 600mW FPV works perfectly.
    Then I upgraded with Arris CM2000 gimbal, small gps tracker, total weight is about 1250 g.

    Now everytime I fly either in GPS or Atti and left throttle at center, Phantom can't maintain altitude. I have to constantly adjust throttle.

    I always do compass dance, LED status is always green before I start flying, even do the Advanced Calibration and lastly try to increase vertical gain to 125% but still it can not maintain altitude perfectly, although a little bit stable compare to vertical gain 100%.

    Any ideas what else should I check ?

    Thanks
     
  2. martcerv

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    Your pretty heavy there and using stock 8 inch props or even worse graupner 8x5 style possibly? These are going to struggle, not sure how much extra power your gimbal draws but first thing to try are some 9 inch props.

    I use 9050 gws triblades and these fly great even at 1.3kg total weight but normally I fly around 1.2kg. Having props with not enough lift for such a heavy phantom will give you issues. DJI rec9mmends max weight of 1.2kg on a phantom but changing props will give you more lift.

    I assume along with your lack of lift you are also getting very short flight times. If your very heavy and props need very high rpm just to maintain lift any pitch angle will likely make it lose altitude. If the gimbal is also drawing more power then this is only going to hurt more. I found a similar result trying different props whenever using props not really suited and not giving enough thrust.
     
  3. felas

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    Yes, I am still using stock prop. Flight time indeed reduces a lot from 8-10 minutes, now only 5 min top. I will try with 9" prop then.
     
  4. miskatonic

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    Not just 9" props, 9" tri blade props.

    Are you also using a single stock battery to fly this beast?
     
  5. martcerv

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    I prefer the 9 inch triblades but even DJI style profile 9 inch dual blades will be much better then stock 8 inch props. Id stay away from anything with the graupner profile as even at 9 inches the graupners barely give as much lift as a stock 8 inch prop in my tests. The new DJI 9 inch blades may be worth a try but I still havent found anything to match those GWS 9050 triblades on a heavy phantom.
     
  6. felas

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    Yes, I am just using single battery. After I weight again, found out that my set up was around 1350 g ! :). So start dumping several item like prop guard, gps tracker and small2 parts like CF for Video tx base and just stick tx directly to phantom body. Now it's around 1250 g, . I also readjusted vertical gain in Assistant Software up to 200%.

    Tested again and seems very much stable when hovering. Flight time also increasing around 6-7 minutes. Last thing to try will be 9" props as soon as I got ones.
     
  7. miskatonic

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    You might notice that your stock battery is getting warm after flights. If it is getting warm you may be putting too much strain on the battery. It may not be up to the of lifting that much weight. It may be time to switch to higher C battery or run parallel batteries.
     
  8. martcerv

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    1350g is very heavy and stock props would really struggle, also be aware when flying heavy using props that arent generating much lift. If you get to level 2 battery protection and the NAZA starts to reduce throttle percentage it will quite likely just fall out of the sky like a brick. Using the triblades it still does ok and you can still descend at a controllable speed, when I tried regular props I noticed at this point it was just coming down fast no matter what you did.
     
  9. felas

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    Are you using stock motors with the triblades props ? I don't know why my setup up is very heavy, while its quite similar with others. Single battery, Arris Cm2000 v5 gimbal. Gopro H3B, Immersion 600mw Tx and infinity Hobby CF Landing gear.