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Just so I'm clear on this-ATTI vs. GPS modes and flyaways

Discussion in 'General Discussion' started by radioguy, Dec 8, 2014.

  1. radioguy

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    As I grow in the hobby, I'm flying my P2 more and more in ATTI mode so I don't have to rely on GPS. This got me thinking, and wanted to put this out to the brain trust-if I'm flying in ATTI mode, my Phantom is not relying on any GPS information, but only what the Naza "sees". Therefore, anything that could cause a flyaway would be limited to either a disruption to the radio control system (and what the Phantom receiver hears), or a really, really strong wind gust out of nowhere.

    Any thoughts? Am I on target?

    Thanks much!

    Fred in OKC
     
  2. msinger

    Approved Vendor

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    Re: Just so I'm clear on this-ATTI vs. GPS modes and flyaway

    Depending on your settings, your Phantom will RTH or auto land when the battery reaches a certain level. I've seen some people talking about issues where that function kicks in when the battery is still 50% full. I wouldn't consider the RTH a flyaway, but some might when they see their Phantom shooting straight up into the sky as it's trying to reach the set RTH altitude.
     
  3. Hughie

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    Re: Just so I'm clear on this-ATTI vs. GPS modes and flyaway

    Or mechanical failure. Not sure how long a P2 would stay airborne if an ESC or motor or prop failed, but I am pretty sure it would start by making undemanded movement in a given direction.

    Also, in IOC mode have you considered Course Lock. Home Lock wont apply because that needs GPS, but I think Course Lock does not. If you accidentally select CL you wont directly get a flyaway but it could contribute if it were not flying in the direction you though it was.

    As far a I am aware ATTI = NAZA + IMU + Altitude from Barometer
     
  4. radioguy

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    Re: Just so I'm clear on this-ATTI vs. GPS modes and flyaway

    I leave my transmitter in CL mode. To my knowledge, I've never used HL mode. It's either GPS or ATTI for my P2.
     
  5. doug86

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    Re: Just so I'm clear on this-ATTI vs. GPS modes and flyaway

    You forget the single biggest cause of flyaway: human error.

    Other things that could cause problems:
    -a bad S1 or S2 switch. there was a rash of that going around for a while.
    -loose plugs inside the body
    -magnetic interference messing with the compass

    I think it's become our urban myth that flyaways are caused by GPS problems. As your question already points out, the thing will fly just fine WITHOUT a GPS signal, so how does loss of GPS account for loss of control? Sure, GPS could be an issue, but IMO, avoiding the use of GPS doesn't reduce your chances of losing your Phantom.

    your mileage may vary
     
  6. Hughie

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    Re: Just so I'm clear on this-ATTI vs. GPS modes and flyaway

    Assuming the GPS is serviceable, it could be a flyaway issue if Home Point is not set properly. As you say at the top, human error.
     
  7. ianwood

    ianwood Taco Wrangler
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    Re: Just so I'm clear on this-ATTI vs. GPS modes and flyaway

    This is not the case. GPS is not a common cause of flyaways. If switching to ATTI restores control, something else was at play (e.g. autoland, RTH, etc.). Mechanical failures similarly don't often result in flyaways and usually cause an abrupt descent.

    Most all true flyaways that I've seen are consistent with either a compass or IMU issue. The only way to work around those is manual mode.