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2 quick ?s: shell & ATTI

Discussion in 'General Discussion' started by QYV, Jul 26, 2014.

  1. QYV

    QYV

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    I don't have any stickers applied and wasn't paying attention last night and I mounted the top shell on backwards. I don't have my good tools and really don't want to turn it back around right now... could it cause any problem? I think it's just the GPS receiver up there so I don't think it matters? I've flown a couple times before I even noticed... no issues and the Home Point seems accurate via my iOSD.

    I'm also in Naza mode now and starting to fly in ATTI. I'm pretty sure I know the answer but ATTI isn't just lateral float, it's vertical as well yes? so like if there's a sudden updraft or downdraft you will gain/lose altitude with the wind?
     
  2. ChuckMRN

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    I'm pretty new to all of this, but what I do know is if your build your own (ie 450/550) the GPS has an arrow on it and must be facing forward. My best guess is GPS is directional.

    EDIT
    Those units have a built-in compass, plus doesn't.. Mine is stable in ATTI as far as elevation, but will drift with the wind
     
  3. OI Photography

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    Top shell definitely needs to be oriented properly, the GPS antenna inside is directional and will seriously throw the NAZA off if it's not in alignment with the direction the NAZA expects it to be. The screw holes for the GPS board in the lid are uniquely offset so you can't mount it there wrong, you just have to be careful to get the lid back on properly.

    As for ATTI, that mode only stabilizes the attitude of the aircraft, i.e. no roll or pitch unless you give stick input in that direction. When in this mode the Phantom should maintain a level attitude, but it will drift laterally with the wind and may be carried up or down as well with drafts or currents.
     
  4. QYV

    QYV

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    awesome thanks! Switching it back now
     
  5. ElGuano

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    2 quick ?s: shell & ATTI

    Respectfully, on a phantom or p2, you can leave the shell on backwards. The gps is entirely nondirectional, it's the compass on the leg that must be oriented to the front of the quad. The screw holes are only directional because they match the pcb pattern of the separate Naza gps/compass puck, more of a manufacturing efficiency decision than anything else.
     
  6. OI Photography

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    :eek: Good to know...I thought I had seen reports of erratic flight at launch that was cleared up when the lid was put back on in the proper direction
     
  7. ElGuano

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    Re: 2 quick ?s: shell & ATTI

    i

    I think we used to see reports about that because in the olden days, people tended to rely on the arrows embossed into the shell to tell you which props to put on which motors (prior to self-tightening props). If you rotated your shell 90 degrees, you would put the cw props on the ccw motors and yeah, it'd instacrash :O. Nowadays you literally can't get it wrong, so the shell orientation doesn't matter (unless you mistake your orientation by looking at the stickers).
     
  8. Wedeliver

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    if the shell direction don't matter, how does the craft know which direction is forward? i put mine on wrong once i think it was off by 90degrees and i realized it when i was flying and it was not going in the ditection i wanted it to go.
     
  9. ElGuano

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    The compass on the leg is directional. The part of the compass that points forward tells the Phantom which way the nose is pointing. If you flip the D-bracket and place the compass on the opposite leg, the Phantom will think it is facing backwards, and the inconsistent data between the compass and GPS will confuse the flight controller and cause the quad to spiral out of control (the so-called "Toilet Bowl Effect").

    I don't have an answer as to why your top shell being off 90 degrees would affect flight, could it be that you were looking at the stickers and that made you think your Phantom was pointed 90 degrees off its actual heading?

    Here's a picture of my Phantom, you can see how much I've messed around with orientation on it--the shell is rotated, the Naza is reversed, the compass is on a different leg. I don't even bother looking to see which way the shell is pointing when I put it back together :)
    [​IMG]
     
  10. Wedeliver

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    You have a very pretty quad. what gimbal are you using?

    I am sure the problem I had flying when the upper shell was on wrong was that I had no idea what way was forward.


    so, I am still confused by how the quad knows which way is forward. For some reason my mind wants to think this is a different parameter then which way is north, which is what I thought I taught the quad when I did the compass dance. Like for my radar detector where I drive in circles and then it knows which direction is which by compass. (which is what you are saying but for some reason I am having a hard time wrapping my head around it).. I think about my other flying machines and they seem to know which way is forward without any compass setting. now ioc brings a whole batch of software to the table and can turn around any "PHYSICAL" items that set which way is forward in the craft.

    trying to find answers I found out why folks think they can fly without doing anything, just unbox and fly away.. that's what this following link says.

    http://www.dji.com/product/phantom/feature
     
  11. ElGuano

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    It's a Tarot T-2D. I've been thinking about upgrading to the H3-3D, but it's a bit more complicated for my setup than most :)

    The arrow always points forward.
    [​IMG]
    [​IMG]

    The Naza will always consider the arrow as the direction the nose is pointing, always. When you calibrate the compass, you are telling the Naza what those coordinates are (the nose is pointing 180 degrees, or 183 degrees, or 291 degrees).
     
  12. QYV

    QYV

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    try to disconnect yourself from the idea that the quad has a "forward" at all. "forward" is a relative term we use to make it easier on our brains and keep the lateral stick movements logical (and help with the camera obviously) but the quad is omnidirectional it just knows go in "that" direction when you move the stick.

    The quad has to have some way of knowing which way is... let's call it "forward" and that way it knows is (according to ElGuano and it makes complete sense) to know which leg the compass is on. As long as it knows which leg the compass is on, it knows when you press the stick in a certain direction (let's call that "left") it will move itself in that direction.

    makes sense why if you move that compass to a different leg, the Phantom has no way of knowing you did that so now when you press "left" it goes in a different direction because it thinks that's where it's facing.

    anyway getting back to the original issue, fwiw I made several flights with the compass on "backwards" and didn't have any trouble. RTH even worked properly I always try it just to feel comfortable before I go out 300-400+ meters.