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Question about flight modes.

Discussion in 'Pro/Adv Discussion' started by HWCM, Jul 5, 2016.

  1. HWCM

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    When flying in P mode, on the map there is a green or yellow line drawn to show the direct route back to home. If I fly out a couple miles and it looses satellite connection for some reason and it switches to atti or if I have a compass error, will that line still be there? So I can fly back manually. If not, will RTH work if I hit the button on the controller?
    I could probably test this myself, but I was just sitting here thinking about it because I flew over some heavily wooded rolling hills (small mountains really) with no reference but trees. I was wondering what I would do if I lost GPS, compass, video or all three.
     
  2. Numone

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    Think the line would be on the map. If you lose R/C signal for < 3 secs RTH should automatically switch in. I don't think hitting the button on the r/c initiates RTH; I think you hit the RTH symbol on the go app, don't you? If you were to lose GPS, compass and video I think in theory, if it was still in the air, you could retrace back but someone will be along with a definitive in a moment I'm sure....
     
  3. HWCM

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    You can do both. Have you never noticed the big button on your remote that says RTH? It is to the right of the power button. They look the same.
    You think it would be, so do I. But thinking twice about it, if there is no compass or GPS how would the flight controller know which way to go? Hmmm
     
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  4. Numone

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    Yes SA, I've seen that one. I've tried to initiate RTH using the button as a test and sod-all happened but I can use it to cancel RTH, so maybe there's a setting wrong somewhere.
    So back on topic, you're right of course, it wouldn't know where it was at all..
     
  5. Meta4

    Meta4 Moderator
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    It's important to know how to activate RTH so that you can when you need to.
    Go out and try again.
    This time try to press and hold to activate RTH and just a simple press to cancel.
     
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  6. Meta4

    Meta4 Moderator
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    Rather than getting too excited about the hypothetical scenario, understand that you aren't going to lose GPS unless you fly deep into a narrow canyon, under a roof or in a forest.
    If you did lose GPS your Phantom would be in atti mode and you would have full control but it would not be able to RTH.
    You aren't going to lose your compass in flight and as long as you don't calibrate it close to steel objects, you probably won't get a compass error in flight either.
    If you lose video, or the app crashes, you still have full control and RTH.
    Having practised with RTH you would be able to confidently bring the Phantom back even if it's out of sight.
     
  7. HWCM

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    Sod-all? Edit:You have to push and hold the RTH button to activate RTH.
     
    #7 HWCM, Jul 5, 2016
    Last edited: Jul 6, 2016
  8. HWCM

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    I am not getting excited at all. Calm down.:cool:
    Yes, thank you. I know all of what you are pointing out. I have been building and flying quads for years. I have had GPS modules burn up mid flight before. I have had compasses go completely out of wack mid-flight before. I know I would have full control and I am very well capable of flying with the sticks without a compass or GPS or even a gyro. I was asking if the yellow or green direct line to home would still be accurate on the app in case I was far away and could not tell my orientation. I know it uses the GPS corordanince and compass to show on the tablet which direction is home. I was curious if it used what it knew before the malfunction or if the guidance lines disappeared after the malfunction.
    I have used the RTH function many many times on many different builds. It is definitely a much appreciated function when it is needed, that is when it works correctly. ;)
    Thank you for your input though. I got a chuckle out of it.
     
  9. Numone

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    Yeah, will do later today. Knew it'd be a case of UO! Was too impatient and certainly didn't hold the button long enough. Dickhead! LOL!
     
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  10. Vertigo

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    yeah, we've never seen that happen :/
    Phantoms never fail to RTH.
    Kp index never spikes either.

    Worrying about "hypotheticals" that are extremely likely to happen at some point, is precisely what any drone operator should do.
     
    mrgoodwrench, Numone and HWCM like this.
  11. Meta4

    Meta4 Moderator
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    KP Index?
    That's beyond hypothetical ... it's mythical and much-hyped beyond all reality.
    There's never been any case of KP index affecting Phantom flight that I've been able to track down.
     
  12. Vertigo

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    There is nothing hypothetical about KP index. You do know how its measured right? By using ground based magnetometers, just like the one in your phantom. Its an actual measurement of compass errors due to -mostly- solar activity. You can argue over at what level it affects our drones, but when it hits 9 or 10, I assure you its not a mythical thing.

    As for losing GPS; that also most definitely happens, its happened to me plenty of times, and not just when flying without clear view of the sky. GPS signals are radio signals and can suffer from radio interference; either from ground based sources or ionization of the upper atmosphere. They are also influenced by thick clouds.
     
    #12 Vertigo, Jul 6, 2016
    Last edited: Jul 6, 2016
  13. Meta4

    Meta4 Moderator
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    The KP-index affecting your flying is a much hyped myth with no evidence that it has ever caused any problem.
    The commonly held belief is that at KP-index of 5 or above, the sky will fall and your Phantom will fly away, etc, etc.
    But no-one has ever come up with any evidence of problems caused by flying with a high K-index.

    The general idea is that it will affect GPS accuracy, because high K-index conditions do have an actual small impact on GPS accuracy.
    But just how much and what impact does it have?
    Here's something to look into: http://www.nstb.tc.faa.gov/reports/PAN86_0714.pdf
    Look at P31-32 and you find that GPS errors were measured at a couple of metres.
    But GPS already has an error of a metre or three anyway anad you don't even notice that when flying.
    If you flew with a slightly larger GPS error what impact would that have?
    Probably nothing you'd ever notice.

    By the time KP-index is high enough to cause .
    GPS affected by clouds? Really!!!
    You've just given your credibility away.
     
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  14. Vertigo

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    GPS signal work at microwave frequencies. Water (vapor or ice crystals) does affect it. Im not saying you cant get good reception on a cloudy day or even below a giant CB, Im saying thick/thunderclouds will impact the signal, as will many other factors that combined can contribute an increased HDOP or losing your GPS lock. Saying that never happens only shows your ignorance. Ive been working with GPS in aviation since 1986.

    As for the KP index, I never claimed its on important factor for GPS reception. Its main effect is on magnetometers, not GPS or radio waves. Though it it can impact those too, usually to a much smaller degree.
     
  15. Meta4

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    So are you just going on about trivia or is there anything in this that has any effect that anyone will ever notice?
     
  16. Vertigo

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    Even though I typically fly in attitude mode, I tend to notice when I lose my GPS lock. People also tend to notice when they have compass failures.
     
  17. Meta4

    Meta4 Moderator
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    You fly in atti but know when you lose GPS lock?
    People notice when they have a compass failure?

    I was asking if any of the other stuff you mentioned would have any noticeable impact on anyone flying a Phantom. (hard to see how your examples have any relevance)
    eg .. KP index .. Are you aware of anyone that has ever been able to show that a KP-index above 5 had any impact on their flying?
    GPS/clouds .. has this ever had any impact on anything?
    Or are you just talking about trivia that has no measurable effect on anything?
     
  18. Vertigo

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    Im telling you GPS and compass failures are not some extreme rare occurrence and most definitely not just a result of not calibrating in situ or not flying with a full battery or whatever the popular go-to theory of the day to explain yet another flyaway. Saying that it isnt going to happen and to just rely on RTH working is bad advice. These failures happen and its something that any RPAS pilot should be prepared for. What actually causes the failures is not relevant to this discussion, but I named some factors.

    If you want to start a discussion about what precise KP level is actually dangerous (I never said 5) or which sources of interference are most likely to affect your GPS signal, I suggest we do that in a different thread.
     
  19. RémyHeli

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    KP is not a myth, ie GPS position can 'bend' up to 30 meters in Europe. Context is of importance, high KP condition not welcome if fly conditions are already bad such as low number of visibles satellites.

    Here is the different thread!
    Solar Flares


    Sent from my iPhone using PhantomPilots mobile app
     
  20. Meta4

    Meta4 Moderator
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    KP index isn't a myth, but the so often mentioned risks of flying when the K-index is 5, 6 or 7 is.
    If you search forums you find loads of posts suggesting you shouldn't fly if the K-index is 5 because your Phantom will fly away
    The post you mentioned confirms this.