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Phantom losing altitude in Atti mode

Discussion in 'General Discussion' started by VoicOfReason, Sep 14, 2014.

  1. VoicOfReason

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    Today I was flying out about a half-mile from home in Atti mode. On the return trip in Atti mode, I noticed I was losing altitude fairly quickly. I quickly switched into GPS mode and ascended. Does it sound like I may have been absentmindedly slightly descending with the left stick while flying or MIGHT this indicate a problem with an on board system?
     
  2. Mike

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    My P2 loses altitude when flying full speed in atti. It holds pretty well when flying slower.
     
  3. Zinnware

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    You did not state the version of software on your bird. Older versions like 1.08 will definitely loose altitude in ATTI mode. I noticed that version 3.06 holds altitude pretty well for my Phantom 2 with a H3-3D.
     
  4. Jayson Hanes

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    totally normal on all versions that i've used since the P2V+ came out up to the latest.. you just have to keep an eye on that altitude when you hit 45+mph :)
     
  5. VoicOfReason

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    So, today I tried flying in ATTI at full speed. I pretty much had to push the altitude throttle up all the way. Normal, too?
     
  6. Jayson Hanes

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    in atti at 45mph, from 400 feet, I have to be careful not to fly into trees. Atti is not gps stabilized.. therefore it is totally normal. The phantom may have a barometer but there doesn't seem to be any priority to maintain altitude if you're zooming. Try normal mode and flying forward :)
     
  7. ProfessorStein

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    Are you using the nipple grip again, dirk? :shock:
     
  8. ProfessorStein

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    It does seem like it might be a firmware version difference... but I haven't actually seen any of the guys having trouble post what versions they're on... only Zinnware, who's on the latest and he's not having trouble. Last I checked you were on 3.06, too, right dirk?
     
  9. Mike

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    I'm on 3.04 and mine loses altitude when I floor it.
     
  10. Jayson Hanes

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    I don't get what the big deal is. It makes sense for it to lose altitude in atti when you are flying fast...
     
  11. ProfessorStein

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    No big deal. And you're right, in a way... it does make sense mechanically. But it also seems as though some Phantoms do and some Phantoms don't. So... we're just trying to figure out the difference. Because... given the choice... I'm pretty sure most pilots would opt for the Phantom that doesn't.
     
  12. Jayson Hanes

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    I'm pretty sure that for those that "do not" lose altitude during "flight while in ATTI" must be only flying to speeds of 25 or 30 mph.. in that, they are simply not flying fast enough or are flying into a headwind preventing top speeds. I've not bothered to identify at what speed this becomes more obvious, but I don't think it's a stretch to say that any speed below 35 mph is pretty tame.
     
  13. ProfessorStein

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    Ummm... nooooo... if you happened to read the thread entirely, you'd see that dirk was travelling at 40mph and did not lose altitude (in fact, he gained it, though only negligibly). And Zinnware stated he saw altitude drops on earlier versions of firmware but now, with newer firmware, not.
     
  14. BlackTracer

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    I am definitely going to retest this myself. I know for a fact that with 1.08 which I ran for 4 months on my plus, it lost altitude when pitched/rolled and moving at 25-50 mph. I haven't extensively tested with 3.06, but I plan to.
     
  15. VoicOfReason

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    For what's it's worth, I had a Micro Drone 2.0 where you had to crank the throttle upward when moving forward otherwise you lost altitude. I just got used to it.
     
  16. Damon

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    In ATTI it is clearly a conflict in the software code and the physics of the P2. Your right stick is telling it you want full pitch or roll 25% in version 3.06. The P2 can not maintain that commanded pitch and ascend too. Its priority is the pitch. If you let off the right stick slightly then it will ascend listening to the throttle command.

    This is even more obvious when going into headwind with all the wind pushing downward on the now diagonally faced top of quad.

    It is not a factor in GPS because the P2 can maintain 15% pitch and ascend without the two cancelling out the others command.

    In my experiences in no wind the loss of altitude is very slight, maybe .05 meter descent per second or less. In head winds I've seen over 1.0 meter per second descent. Normally on right stick let off the P2 climbs back up to its original height.
     
  17. macheung

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    I routinely fly pretty fast on the return leg on my long distance runs (2-2.5km) and do not usually notice any lost In ATTI mode going 25-30 degrees of pitch (v2.0 firmware). I suppose it is possible for the p2 to not generate enough loft at high tilt angles, but I have not seen that at up to 30 degrees or so in pitch. My estimated airspeed is about 15-18m/s, ground speed about 16-22m/s due to wind).

    Granted, my long distant runs are usually into the wind, so the high speed return leg is typical downwind.