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Fly Away theories

Discussion in 'General Discussion' started by phantomi, Sep 3, 2014.

  1. phantomi

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    I have read about some fly away situations were the human error factor may be minimized because the users are experienced ones and take all the step to avoid it. Can be there an intrinsic hardware problem that can result in fly away that can not be prevented? Want to hear about theories about this, if you, like me, feel that a fly away situation can strike at any moment.
     
  2. N017RW

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    Yes... component, system, human, or workmanship failures to name a few.

    You'll have to accept the risk or build them for static display only.

    Many who are new to R/C aircraft have never [yet] experienced loss or damage due to the nature of such systems.

    Anytime you are remotely , untethered, trying to operate a 'toy' such as these you should expect the possibility of failure of one kind or another at some point in your career.

    Sure, control systems are FAR more advanced than in the 70's when I started not to mention the other technologies these craft contain. But they will never be foolproof or completely fault tolerant. Just about any failure in the propulsion or control systems will bring the Phantom down.

    Phantoms are on the low end of outdoor type hobbyist multi-rotors and perform very well for their quality and price point but even a/c which cost much more are prone to failure and loss. Not to mention documented industrial or military failures.

    Having said that there are many here, including myself, who have 10's or 100's of flights with no issues. Experience helps but there is no guarantees with this endeavor.

    Remember it's a hobby for most and hobbies cost money... you gotta 'pay to play'. And despite the possibilities, I enjoy every airborne moment with my r/c aircraft.
     
  3. ProfessorStein

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    I've spent a lot of time reading threads concerning fly-aways, and as far as I've been able to tell, we really have yet to see any fly-aways that could be contributed to anything other than either pilot error during flight, or poor pre-flight maintenance.

    And I believe we've established that switching to ATTI during a fly-away can recover control. So I find I'm less and less worried about fly-aways, actually. I have close to 100 flights, now, and have not experienced any problem whatsoever, except a couple of drift issues that I can trace directly back to poor compass calibration or, with this latest one, a motor that's going bad.

    I truly do not believe that there is anything intrinsic in the hardware that can result in a fly-away.

    However, as N017RW pointed out, a lot more issues can come up that cause, not a fly-away, but a system failure... typically resulting in your bird coming down. Is that any better than a fly-away? Probably not. But it's a whole different ball of wax.
     
  4. phantomi

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    Thanks. I'm aware that component, system, human, or workmanship failures can bring the Phantom down, and has accepted the risk. But the fly away situation is particularly unique and allegedly one that can be prevented or at least recovered from.
     
  5. discv

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    The odds of experiencing a genuine flyaway is approaching nil. Forget it and enjoy.

    Carry out pre flight checks, missing not one step.

    I could not guess at the numbers of Naza flight controllers that have been shipped. But many hundreds of thousands certainly.

    Over the years I have read of less than 10 100% genuine flyaways.
     
  6. rrmccabe

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    My theory is anytime the Phantom does something the pilot did not expect and crashes somewhere it is OFTEN labeled a fly away.

    What once perplexed me when I was new and I considered a bug/flaw/defect makes sense now and is easily recoverable in all my situations so far.

    I think the most important thing a new pilot can do besides read the manual, is go to an open area under controlled circumstances and test RTH, Home lock, resetting homepoint at various elevations and invoking failsafe, run the battery down and watch it autoland, switch it to ATTI with a light wind and just see what happens.

    Once you do all these things you have a better understanding of what the Phantom tries to do under various circumstances and ways to correct them if needed.
     
  7. discv

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    I like that. New pilots can simulate their own 'flyaway' ;)
     
  8. rrmccabe

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    It's a great way to learn. GPS mode is just a flick of the toggle away. Best to see what no GPS does in a controlled situation, and how to react. Best not to be surprised and have to figure it out.
     
  9. ProfessorStein

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    Well... since 9 times out of 10, that's what new pilots call a fly-away... it makes sense ;)
     
  10. ElGuano

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    Of all the reports, theories and accident analyses I've seen, there is never a single, corroborating fact that points to a uniform point of failure in the hardware or software. It could be that there isn't enough information out there, or that people tend to be quite bad at recollecting and recounting a situation in stress that happens and finishes over a few seconds time, but I haven't seen anything that points to an addressable fault in any given component. To me, that suggests that "flyaway" is really nowadays a generic term for any loss of pilot control.

    When there is something actually systemic, it tends to show up quickly, with even small data sets. For instance, the old WKM gps overvolt was reported, diagnosed, and confirmed (with a huge amount of testing) though it arguably impacted several orders of magnitude fewer people than any Phantom/Naza issue claimed.

    I'm not saying DJI is perfect, but clearly the SNR on the flyaway issue is very low...
     
  11. N017RW

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    Yea, flyaway is an unfortunate new word for crash because the FC can often maintain flight whereas with the old 'planks' and CP helis (before FCs) would just return to earth more quickly... sort of speak.
     
  12. Buckaye

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    I agree with another poster on here who said - it's a risky and can be expensive hobby.

    Once you get that in your psyche - it makes the worry easier to handle :)

    That said - my most frustrating moments as an RC pilot have come from the "random" crash - or one that didn't seem to be my doing. But here's the bad part...

    Of the crashed that seemed random - 90% of them were somehow my doing :(

    Here are some of the mistakes I have made:

    1. Bad solder joints - wrecked a TREX 600 flybarless - $250.00
    2. Didn't tighten the "Jesus" bolt on a regular bolt check - remarkably on $50.00
    3. Probably $1000.00 in several crashes doing maneuvers I wasn't ready for :)
    4. PHANTOM - set second waypoint behind first waypoint and used a banked turn on iPad Groundstation - not considering a tree/altitude correctly.... maybe $20.00 (new blade, gimbal dampners and 2 Gimbal dampner locks)

    The closest I got to a Phantom fly-away was another altitude issue combined with bank turns where I set the lowest altitude too low and crashed into some grass. Though I think the design of how the iPad Ground station and Phantom measure altitude could be more user friendly - it turns out the fault was really mine... for being too cocky having had the Phantom for exactly a week LOL.

    The only absolute random "fly away" issue I had was with the Align FBS - it's firmware was pretty buggy and I had an issue where it got out of control for a few seconds before I brought it down hard (luckily only minor breakages).

    I guess - the crux of my response is - it may seem like people are exaggerating when they state things like "almost all" fly-aways are newb pilot errors... but it probably is a lot more user error than anything else.

    The one subject that really has my interest lately is the early auto-landing thing... that one bugs me a lot because in Florida you cross little bodies of water almost everywhere...
     
  13. syotr

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    In a true flyaway situation, the bird just takes off in some random direction with no response to input from the controller, this after properly establishing home position. (dropping out of the sky because of VRS or power failure is a different thing.) Changing to ATTI mode may recover if the problem was GPS related. Activating return to home does nothing as this requires GPS to be working.
    No one really knows what causes these flyaways since we don't have a "black box" recorder to show what was going on in the program at the time of failure. These are very complex machines with lots of parts. Any number of mechanical or electrical problems could cause a flyaway, failing motor, overheated component, stuck sensor, bad solder joint. Vibration and electromagnetic interference can also cause such problems.
    Many here will pull some made up statistics out of their azz and say that 99.9% of flyaways are pilot error because it has not yet happened to them. There have been too many cases where experienced users, following all proper procedures have watched their Phantom suddenly fly off in the middle of an otherwise normal flight. I feel sorry for those who have had this experience, especially when they post here and have everyone pile on them saying they must have done something wrong.
     
  14. N017RW

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    In my plank days we called it a 'lock out' or similar because as was stated you have no control.

    The a/c control surfaces may freeze and gravity takes over quickly or it my climb, bank, dive, loop, roll, etc. and remain airborne awhile longer but the end result is the same... often a few less things to take home.
     
  15. ElGuano

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    I don't think we can draw any conclusion on a single use case being the one and only "true flyaway" situation. It's very common to hear a claim that there was "no response to TX at all" whereas we know when a Phantom builds up enough speed, the time required to respond appreciably to tx input may not be enough before it careens into a wall or tree. Sometimes experienced pilots claim non-responsive TX, and iOSD logs may show the opposite, just that there was an accidental switch into manual mode before the crash. Gravity happens fast, there's not a lot of time to note anything.

    This happened to EMCSQUAR, he's one of the ones here I don't doubt when he actually describes what happens and says what he did to counteract. Unfortunately, in the vast majority of flyaway claims, the OP gives so little information that it's hard to do anything other than speculate. But there's such a prevalent tendency to immediately default blame the flight controller when the problem could be any of dozens of other components critical to maintaining flight, that a lot of focus is spent corroborating or debunking that variable.
     
  16. cshaw

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    I had a loss of control event recently and crashed into a forest. Looking back I think 2 things went wrong.
    1. I am not sure that the compass calibration I did right before the flight was OK. It seemed to be, the lights went out, but I didn't actually check the screen to make sure the P2V+ was in the middle of the radar screen. I now recheck the compass calibration every time.
    2. When weird stuff started to happen. and the Phantom started to lose position I was over a lake and probably panicked a bit. Trying to head for dry land as fast as possible and switching to ATTI mode probably did not improve the situation at all.

    Luckily the phantom made it through the trees to the ground and was completely undamaged.

    My last few flights have been in a big field practicing actually flying the thing to try to improve my response to unpredicted movement. ATTI mode is not for the faint-hearted and GPS mode is too easy for beginners to get into trouble.

    Back flying RC Helis I usually took off about 30mins after arriving at a flight location. Spent the time checking and rechecking everything. Now we expect to just rock up, poke in a battery and fly.
     
  17. darwin-t

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    I can think of one. FC40s, at least, come with the altitude and distance limits set at 2,000 yards. That is over a mile.

    I don't know what the default limits are on other models.
     
  18. BWJ

    BWJ

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    Maybe the craft will be confused by calibrating on and on every day. :roll:
    You do not have to calibrate your compass before every flight; this is not necessary and may actually increase your chance of having a problem. DJI recommend re-calibrating only when moving far away from last flight point.
     
  19. EMCSQUAR

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    Adding my 2cents to the conversation, yes I had a fly-away and yes it took off on it's own. On some of the tests I've done on DJI equipment I've literally invited a flyaway to happen -> https://www.youtube.com/watch?v=RvNUzi5 ... VSNdmm127A

    Yet the one & only REAL flyaway happened in ideal conditions and later was found to be a glitch in advanced IMU calibration in newly released MAC assitant software for NAZA M V2. Once I retrieved my Phantom I recal'd it w/PC and it flew as normal. I then tried MAC software and was able to duplicate it. I then contacted DJI I showed them results which they immediately found & updated MAC asst.

    Overall I feel DJI updates love them or hate them are making fly aways few and far between, but there are certain conditions that if a pilot is not aware of could be conceived as a flyaway. IE: flying low over calm water or a frozen lake - water/ice will relect Tx control signal in a dozen different directions. Or flying in high RF areas - get/download apps that show current RF freqs around your flying areas. Biggest thing is to know what your aircraft limits are and get familar w/them.