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Phantom 3 can get blown away...

Discussion in 'General Discussion' started by kelleysislander, Jan 19, 2016.

  1. kelleysislander

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    Hi All,

    I have been dong multi's for a while now and just got my first P3P and of course studied the stock firmware and the DJI GO app, then explored the various 3rd party apps with a primary focus on performing waypoint missions.

    Along the way I ran across this guy who almost lost his P3P due to the stock DJI implementation not allowing any more power to the motors than is needed for the 11 mph or whatever "speed limit". Well, you'd think that was fine until you watch this guy's video here: where the Phantom was too stupid to realize it was getting moved off of its course and maybe it would be appropriate to apply a little more power to save the day.

    I run a DJI 450 quad with similar motors and props and that thing will hold position in a 30 mph wind (haven't tried any faster) simply because the propulsion system is quite capable of that performance. I bet it will do more just because that thing will actually fly close to 42 mph.

    As to the 3rd party waypoint apps (who wants an app w/o WP capability anyways), they pretty much fall into 2 camps: Fully Autonomous (ie, Litchi) and Controller Dependent (ie AutoPilot), where the former lets you create waypoint missions offline and upload to the controller, and the latter where the signals all run from the controller in real time. The former lets you run the mission even when you have lost radio contact, and the latter aborts and does a RTH (kind of limiting when you may want to do a mission where you want to fly, say, over a tree line and descend on the other side, all still within radio range except for the trees as obstacles).

    Of the Fully Autonomous "Litchi" app I was wondering if what happened with that guy could happen in Litchi, where the stock DJI GO app's RTH was overcome by the wind. I know in Litchi that you can set the (higher than 11 mph) speed to cruise between WP's and can also set the "Stick" speed so that if you move the throttle stick forward you can increase the speed along the waypoint route up to that limit.

    In summary, my questions are these:

    Will Litchi, or any other app, perform a RTH and apply sufficient power to overcome a small 11 mph breeze?

    Will any app allow you to fly past the 11 mph limit in any manual mode at all?

    Thanks,

    Bill
     
  2. N017RW

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    Location:
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    P3 horizontal speed is spec-ed at 16m/s = ~36 mph.
     
  3. kelleysislander

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    Thanks that's good to know!@@

    Cheers,

    Bill
     
  4. RVD98072

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    I watched that video before. I think that guy's issue is that he didn't know how to change his drone into ATTI mode to manually fly it back.

    I would recommend to everyone that they learn how to switch into ATTI mode and use the radar and map to guide your drone back manually.

    Also, it does get windier the higher up you go so he may have been able to lower altitude a little bit.
     
    Reed L likes this.
  5. kelleysislander

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    Yeah, I kept on thinking about the the wind gradient as well... Noticed that effect when launching those chinese lanterns... seems like once you reach the windy altitude those things really took off.

    I'm thinking, RVD98072, that even P-GPS would allow you to override like ATTI, unless P-GPS, like RTH, limits the power output???

    Cheers,

    Bill
     
  6. WetDog

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    He basically let the drone try to fly itself. It will do that under some circumstances, but clearly not all. Yep, learning how to actually fly the thing is useful. At least he got it back...
     
  7. Meta4

    Meta4 Moderator
    Staff Member

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    It's not the Phantom that's stupid.
    It was the pilot's 2nd flight and he clearly has no idea what he's doing.
    A couple of relevant points:
    1. He has strapped 2 pairs of sails (prop guards) onto his Phantom that catch the wind and make it much harder for the Phantom to deal with wind.
    2. He took off with only 50% battery
    3. He flew away downwind in strong windy conditions
    4. He's got no experience with RTH and doesn't understand that RTH has a top speed of 10 metres/sec as opposed to the normal flight speed of 16 m/s.
    5. He just sits there watching his Phantom getting blown away rather than pushing the right stick to give it some power or descend to reduce wind strength or cancel RTH and fly it himself.

    The one thing he got right was the title of the video - how not to fly a Phantom
    The Phantom is more than capable of handling those conditions if not being flow by a complete tosser.
     
    yankee65 likes this.
  8. kelleysislander

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    Thanks for that, Meta4...

    When you said "pushing the right stick to give it some power"... are you describing a Mode 1 controller???

    With a top speed for RTH of 10 m/s, is that only achievable in no-wind conditions?

    If the wind was exactly the RTH velocity of 10 m/s would the Phantom just hover there, unable to overcome the wind?

    I said the Phantom was "stupid" when I really meant "different" or "less better in this regard" from other controllers I have had experience with.

    Based on that experience with, say, the Pixhawk, once you command it to RTH it will execute that command, using as much power as it needs to return. If the wind truly does overcome the max speed of the thing you will lose it, but it will die trying ;)

    The Phantom does things a little differently and just applies the "normal" power required to achieve the RTH velocity, and does not apply the power truly needed to overcome the wind. In that case one must, as Meta4 has stated, know how to fly the darn thing.

    Of course, the one wild card in all of this is that we do not know exactly how fast the wind was up there where that person had it. Maybe it really was applying power and the wind was really above the max velocity of 16 m/s and it just could not keep up. The guy never did disclose the current being drawn, information you could get from a quick glance at the DJI GO app.

    In any event, for me this has raised concerns that need to be heeded about flying these in the wind, something that should be taken seriously...

    Maybe, after all, the P3 really does try its best.

    Does anyone know if that is the case?

    Thanks,

    Bill
     
  9. impilot51

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    Typical. Not understanding the bird, the software, the features and how they work. Love the lessons learned though, and still not really understanding some of the mistakes made....and blaming the P3. What a Doofus.


    Sent from my iPhone using PhantomPilots mobile app
     
    Meta4 likes this.
  10. Meta4

    Meta4 Moderator
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    The default is Mode 2 and that's what almost everyone flies with in Phantoms.
    I meant more speed rather than power ... and that's the right stick.
    RTH will travel at a leisurely 10 m/s in still air.
    I've never heard a plausible explanation why it's programmed that way - it's a limitation we have to understand and work around.
    But knowing about it, it's as easy as to give it some stick and come home 5 m/s faster.

    In a 10 m/s headwind, RTH would appear to be hovering .. for a stock Phantom.
    One handicapped with prop guards would go backwards.
    You can tell when it's windy enough to be a serious concern just from the wind in your ears and hair.
    That's a big enough clue for most fliers.
    Without prop guards a P3 can handle winds of 25 knots (and more if you are careful and know what you're doing)
    Our video guy said that he was too scared to add input to RTH and just let it do its thing.
     
  11. kelleysislander

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    Meta4,

    thank you very much for your reply!@@

    The info is very useful and now I understand everything you have said...

    Cheers,

    Bill