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Initial Phantom 2 Vision experiences and some questions

Discussion in 'General Discussion' started by rjstone, Oct 1, 2014.

  1. rjstone

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    Greetings! I bought myself a Phantom 2 Vision and received it a few days ago. I'm happy to report that I haven't managed to destroy it, or anything else, yet!

    So far I've mostly just been flying it around slowly in the back yard. Problem is that my back yard is sort of like 50x50' surrounded by either a wall or trees or a wall of a house. Even though I'm being extremely careful I'm probably an idiot to fly it around in such a small space, even close to the ground. So far I've managed to damage two rotor blades, though that wasn't due to the confined environment or a typical loss of control. Basically I landed on concrete with the battery alarms going off, and was messing with the throttle control as it was sitting there, attempting to just spin the rotors up and down a bit without actually developing enough lift to take off. Apparently this is bad idea, because the rotors won't necessarily spin up and down at the same speed, and I suspect that's even more true with a 90% depleted battery. So the thing tilted over and ground two of the props against the pavement. So I threw those out and replaced them with some of the spares.

    (I did order prop guards, but I haven't received them yet. I'm pretty sure they would have been sufficient to save the props in this situation.)

    It seems like even with a fully charged battery, you don't want to do anything like spin the rotors up, then back down again, then back up immediately to try to take off. From now on when I land the thing, even if I want to take off again immediately I shut the rotors off, let them stop, then start the rotors and let them reach their idle speed before trying to take off, just to make sure they're all at a stable speed before doing anything.

    Later, due to poor depth perception, bad lighting (extremely bright sun with shade present), and the camouflage effect I managed to clip a rotor on a very small tree (basically one of those ready-to-plant fruit tree type things). At least I can say I didn't hit the tree because I lost control of the thing, but I did totally fail to "see" where the tree was. This was only about 3 feet off the grass, so I somehow managed to escape that with no damage. (The thing flipped over and landed on its top, but amazingly the rotor that clipped the tree showed no signs at all of damage, not even a scratch.) The grass had a bit of dew on it though, so immediately afterwards one of the motors wasn't working. (It was behaving as though one or two of the stator coils wasn't working.) But I just cleaned everything up, used a duster can on the motors, and gave it some time to dry out and it was back to normal. I'm guessing it was just moisture. (I've flown it at least 40min since then with no problems.)

    I did fly it up about 300ft or so two or three times to take some photos, but I'm not very confident that I have enough open space here for the limited accuracy of the GPS to automatically land the thing properly if something went wrong. At one point it lost connection with the RC up that high, but no big deal. I just flipped the switch and regained control, then landed manually. Actually I had it lose connection to the RC about 20-30t from me once, oddly enough, but just reflexively flipped the switch and got it back immediately. Then later I realized that the power on the thing didn't come from the factory cranked up to "FCC compliance" and fixed that.

    I still haven't gotten used to using the right control motion by reflex, especially if the heading is not the same as my facing direction, so I'm mostly flying it around facing away from me. I figure I just need to keep flying the thing around slowly and carefully trying to be really precise until I develop the right reflexes for it.

    Some questions:

    • I notice that the drone doesn't stabilize itself 100% perfectly. This is particularly true if I yaw the thing around quickly. I figure this is probably due to the limits of GPS accuracy, but perhaps I'm wrong. Should I do the compass and accelerometer calibration even though the utility claims I don't need to?
    • No matter what I do I can't seem to get the little "radar" thing to turn into an artificial horizon. What am I missing here? (Seems like I must be failing to see where the option is in the settings menu or something.
     
  2. CallMeAlan

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    My first thought was: RTFM. Thrice. Print it out. Read it again. Thrice. Then go and find somewhere with loads of space, no trees, calibrate. Wait for at least 6 satellites, get the green LEDs you've just read about 6 times, and take it from there. Maybe consider checking K-index and stay at home if it's >=6.

    And GPS is certainly not as limited as you think.
     
  3. HarryT

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    ... And download the DJI "Pilot Training Guide" from the web site, and work through it systematically. Your description is a classic one of trying to rush things.
     
  4. rjstone

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    I did read the whole manual and I just reread it again. It doesn't seem like I've missed anything but I'll reread it a third time.

    The manual does say "Hovering Accuracy (Ready to Fly) Vertical: 0.8m; Horizontal: 2.5m" so how am I underestimating the GPS? It doesn't seem like it's that accurate and any home point where it might try to land automatically needs to be at least 10ft in radius if not 5 times or more that just to be safe.

    Can anyone answer my question about the artificial horizon? The manual (which I've read twice so far, this section more than that) seems to show that it should be there, but instead I get some sort of mini radar.
     
  5. Meta4

    Meta4 Moderator
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    That's about right for GPS. Consumer grade GPS is about that accurate. You can only get pinpoint accuracy with survey grade differential GPS which costs several thousand dollars and won't fit in a Phantom. But the GPS accuracy is plenty good enough for flying.
    I'm not sure what artificial horizon you're looking for - there is none and since the Phantom is self-levelling you wouldn't have much use for one anyway. The radar is extremely useful as it tells you where in the sky your phantom is and which way it is pointing. If you ever fly out of site or lose your bird in the sun, this is your lifeline.

    The manual explains it pretty well and makes no mention of an artificial horizon.
     
  6. rjstone

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    Having read the manual over two times now, I can say it does mention an artificial horizon, just not using the proper aeronautical terminology:
    For some reason they don't use the actual term "artificial horizon", but "(2) Blue and brown areas indicate its pitch. (3) Tilting of the brown and blue area shows roll angle." describes exactly what's in the image and it's exactly what any maned aircraft pilot speaking English would call an "artificial horizon".

    I don't see the icon that's pictured or described in the PDF. It starts out looking like a little radar and tapping it makes a larger version of the "radar" appear.

    So I'm confused as to whether they just removed this entirely for some reason, or if there's some hidden undocumented option somewhere that needs to be set to enable it.
     
  7. Meta4

    Meta4 Moderator
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    Interesting .. just checked your manual.
    I fly the P2+ and there is no mention of the artificial horizon in that manual and no AH in my app.
    But since it's the same app for P2V and P2+ it looks like they never implemented it but left it in the P2 manual.
    Just ignore it - it wouldn't be much use anyway.
     
  8. rjstone

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    Oddly it would be a good feature on the P2V+ because if the gimbal is in full stabilization mode instead of "FPV mode" then it would show you the roll angle of the craft when you couldn't see it on camera otherwise. On the non+ it's less useful unless maybe the camera is pointed way down and maybe you do something insane like try to fly FPV using only the iphone app in full (attitude control off) manual mode.

    They must have been working on it and then pulled it before the P2V+ came out without updating the P2V manual, otherwise there woulnd't been a screenshot. This seems to make no sense when it would be most useful for the P2V+. Maybe they just wanted to force people to enable FPV mode rather than rely on a tiny artificial horizon.