Wookong M GPS Mode - Fair Warning

[222GR]

Just wanted to alert everyone of you flying WKM in GPS mode.... Be very mindful because it is my belief that they are all just ticking timebombs.
I've read enough posts now about Wookong flywaways and lack of input response. I'm simply the latest victim of an already familiar story.

I've been RC Flying for the past 2 years.
107 flawless flights with my S800 that I picked up in 2013. It was essentially an EVO with all the appropriate parts (arms, anti-vibration, landing gear, etc...)
WKM Firmware 5.26 for at least the last 20.
Happened to me on landing 30 feet off the deck after a perfectly normal flight 7 minutes in.
Pulling back towards me to land with solid orientation and Aft stick abrubtly became left stick and then it stopped listening to me all together except for throttle response but that was gone very quickly as well.

FAILSAFE!!!!!!!!.... failed completely as my aircraft began to fly in the opposite direction of home... ugh and holy $%&!

Back to me now still trying to wrestle her back to no avail. It wanted to toilet bowl and climb completely erratically until it aggressively climbed, took off north for a second and then dove for the ground a block and a half away un-recoverably.
The aftermath is purely financial as a beautifully well tuned S800, Z15, NEX7, and of course my costliest LIPOS are thoroughly destroyed and all i want is a time machine to at least get the opportunity to try to get her down in manual - which is a scary as hell prospect when you've got 15 pounds of chaos quickly flying out of your ELZ toward a bunch of homes.

Why did it go crazy and ignore my inputs? I'll probably never know and it's killing me. It doesn't matter how much I look at the data. It shows an issue but gives me no answers.
What will DJI do about it? Probably offer condolences and nothing more. (what did they do for all those that lost expensive rigs due to the now infamous "Flip O Death" that DJI verified as a flaw?)
How can I ever trust anything flying with GPS again? I never will, which is a shame because as much as I love attitude flying, GPS it's incredibly useful and should not be prone to such activity when it costs that much. Is that a crazy statement?
I was wrong when I thought I payed for quality I guess.
Take a look at my Z Compass Data and Satellite, maybe you can tell me what would make that happen. If you want all the data, PM me and I'll offer it up for your evaluation. Look at how crazy SAT validity is 10-5-10-5-10-5-10, etc....

View attachment 18177View attachment 18178

BTW, there was no solar activity that day, and the winds were at most 10 knots. I was out by the oceanfront. Based on the bad data I'd also assume TX interference was not the issue.
If I had known that I was experiencing a GPS issue perhaps my immediate emergency response would have been very different and I would have just dumped it from 30 feet and I wouldn't be looking at a total loss. Then again isn't that what FAILSAFE is for?!?!?!? It did not give me very much time to think but that my friends is where instinctive training will come in handy in your futures.

So my caution to all of you, if you only ever fly in GPS mode, you better be prepared because I promise this is inevitable.

HUGE LESSONS LEARNED!

Not that I'll ever truly trust another GPS flight controller but I'd love some input from you guys on a product that has more proven reliability and a fairly spotless track record if it exists?
Cuz oh my god my confidence in any of this tech is shaken to the core.

MikroKopter possibly???? (the only one that seems nearly as popular as WKM
Is the SYNAPSE still in just in development?
APM/3DRobotics???

I just don't feel like I can put any faith in DJI gear as much as I loved this aircraft. Sigh.

I'd love suggestions on how to proceed from here. Anybody want to buy a motorcycle so I can pay this junk off?

Thanks for listening and fly safe guys. (just not in WKM gps mode)

 

[Scott Drysdale]

Sorry to hear about your flight incident.... If you are genuinely interested it getting at the root cause of the accident..... send us some additional info and we will try to help.
1) What RC radio system were you using?
2) What FC firmware were you using?
3) I could think about more questions to ask but this is a start.

Just wanted to alert everyone of you flying WKM in GPS mode.... Be very mindful because it is my belief that they are all just ticking timebombs.
I've read enough posts now about Wookong flywaways and lack of input response. I'm simply the latest victim of an already familiar story.

I've been RC Flying for the past 2 years.
107 flawless flights with my S800 that I picked up in 2013. It was essentially an EVO with all the appropriate parts (arms, anti-vibration, landing gear, etc...)
WKM Firmware 5.26 for at least the last 20.
Happened to me on landing 30 feet off the deck after a perfectly normal flight 7 minutes in.
Pulling back towards me to land with solid orientation and Aft stick abrubtly became left stick and then it stopped listening to me all together except for throttle response but that was gone very quickly as well.

FAILSAFE!!!!!!!!.... failed completely as my aircraft began to fly in the opposite direction of home... ugh and holy $%&!

Back to me now still trying to wrestle her back to no avail. It wanted to toilet bowl and climb completely erratically until it aggressively climbed, took off north for a second and then dove for the ground a block and a half away un-recoverably.
The aftermath is purely financial as a beautifully well tuned S800, Z15, NEX7, and of course my costliest LIPOS are thoroughly destroyed and all i want is a time machine to at least get the opportunity to try to get her down in manual - which is a scary as hell prospect when you've got 15 pounds of chaos quickly flying out of your ELZ toward a bunch of homes.

Why did it go crazy and ignore my inputs? I'll probably never know and it's killing me. It doesn't matter how much I look at the data. It shows an issue but gives me no answers.
What will DJI do about it? Probably offer condolences and nothing more. (what did they do for all those that lost expensive rigs due to the now infamous "Flip O Death" that DJI verified as a flaw?)
How can I ever trust anything flying with GPS again? I never will, which is a shame because as much as I love attitude flying, GPS it's incredibly useful and should not be prone to such activity when it costs that much. Is that a crazy statement?
I was wrong when I thought I payed for quality I guess.
Take a look at my Z Compass Data and Satellite, maybe you can tell me what would make that happen. If you want all the data, PM me and I'll offer it up for your evaluation. Look at how crazy SAT validity is 10-5-10-5-10-5-10, etc....

View attachment 22368View attachment 22369

BTW, there was no solar activity that day, and the winds were at most 10 knots. I was out by the oceanfront. Based on the bad data I'd also assume TX interference was not the issue.
If I had known that I was experiencing a GPS issue perhaps my immediate emergency response would have been very different and I would have just dumped it from 30 feet and I wouldn't be looking at a total loss. Then again isn't that what FAILSAFE is for?!?!?!? It did not give me very much time to think but that my friends is where instinctive training will come in handy in your futures.

So my caution to all of you, if you only ever fly in GPS mode, you better be prepared because I promise this is inevitable.

HUGE LESSONS LEARNED!

Not that I'll ever truly trust another GPS flight controller but I'd love some input from you guys on a product that has more proven reliability and a fairly spotless track record if it exists?
Cuz oh my god my confidence in any of this tech is shaken to the core.

MikroKopter possibly???? (the only one that seems nearly as popular as WKM
Is the SYNAPSE still in just in development?
APM/3DRobotics???

I just don't feel like I can put any faith in DJI gear as much as I loved this aircraft. Sigh.

I'd love suggestions on how to proceed from here. Anybody want to buy a motorcycle so I can pay this junk off?

Thanks for listening and fly safe guys. (just not in WKM gps mode)

 

[222GR]

Absolutely Scott.
I fly dual Futaba T8FG Super for pilot and camera operator and I upgraded my WKM firmware to 5.26 maybe 2 months ago.
My setup was pretty typical, DJI 5.8 Ghz video downlink, iOSD MarkII (both of which still function remarkably - hell even the WKM still communicates though I'd be terrified to fly it on anything else with a chunk of the IMU case missing. God only knows what got rattled on impact.
Fire away with the questions, I'd love to get some idea if at all possible.

Let me apologize If I appear to be blanket accusing the WKM-M product to be the devil. I'm sure DJI has their issues but I've always taken the negative comments I've read with a grain of salt. I've never had any issue with my gear until now. Sure I wish the QC had been better on a few minor things but it's been manageable.
It might be unfair to jump on the bandwagon but I feel very angry about this and am terrified to be burned by more DJI products if that is in fact the issue.
Funny thing is I just talked to a buddy who works at a local hobby shop today. He was out flying a Blade quad this morning in the parking lot and had a flyaway. Poof. Gone. Miles away probably. No clue. But his experience was eerily similar to mine. Everything he did to regain control and the thing just had a mind of its own no matter what, and this kid is a super experienced RC pilot. It's nuts. Point is Blade isn't using Naza or WKM. no clue what it uses. It is just a toy though.

We're starting to wonder if there's something going on in the area with our large military presence and fighter jets, radar, and what not.
Seems unlikely considering I've had flawless flights a lot closer to the action than that with no problems but who knows, seriously.
I don't read about MK flyaways, or Hoverfly flyaways. Are there bad stories out there just as prevalent with that gear or is it just because DJI is so stinking accessible to the masses that we hear it all? Ahh well another phantom bites the dust yadda yadda.
How can I be certain that it wouldn't happen again even if i strictly flew in ATTI mode or constant Manual (god forbid)

 

[Bluerex]

Man, I am so sorry to hear of your loss - very un-cool!
Can I ask if you were using any of the "Intelligent" modes? I have seen similar things happen to an APM where it decided to switch modes (apparently) all on it's own when flying in IOC mode.

C

 

[Droider]

Sorry to here of the crash.

In my opinion and experience its the firmware from >5.20 that is supposed to put the craft into atti when sats are lost.

I had that happen to me when I first upgraded higher than 5.20. Its the same with the A2. it certainly does not go to atto but a sate somewhere between atto/manual and return to home.

All my WKM are on 5.20

Dave

 

[turkeybird]

I don't think that this will appear anytime too soon, but the days of GPS may be numbered. Interesting tech news : Quantum compass http://beforeitsnews.com/alternativ...ompass-technology-to-replace-gps-2957016.html

 

[Kari]

Agree with Dave, only use firmware 5.20 or even 5.16. Imo 5.16 have been most reliable and i will never update my wkms anymore to anything else.

 

[Scott Drysdale]

I remained with WKM 5.20 firmware until I sold my MR and even then advised the new owner to remain with 5.20..... I did not like what I was reading about the subsequent FW update failures.... There is only so much room inside the "black box" for creeping elegance in the firmware....
once that boundary is approached, too many things go wrong..... at which point it is time to move to a larger and more powerful/efficient "black box".

Case it point.... the original Playstation 3 firmware updates reached a point where the PS3 became a brick.... (internal components overheated and failed).
some claim it is an interesting way to get the buyer to pull out more money to pay for the newer hardware release.

 

[Bartman]

I don't have a WKM but I know the NAZA will exit advanced features when it goes below 6 satellites.....so I wonder if the WKM is the same and if the erratic flying you observed was the heli losing and quickly regaining satellites making it repeatedly enter and exit whatever mode you were flying in.....regarding FAILSAFE, it will only work if it has the satellites to stay in that mode.

so, consider it was experiencing loss of its sixth satellite, it would drop from an advanced mode like IOC but shouldn't have lost GPS Mode (essentially position hold), if it choked on the GPS feed and lost all six then it would drop from GPS Mode and be unable to rescue itself with FAILSAFE. But if it choked on the GPS signals, cleared itself and then repeatedly choked and recovered, it might appear as a crazy a$$ dance in the sky helped by your desperate attempts to see some form of control response.

Plausible?

 

[dazzab]

What really bothers me about such incidents is that they keep happening and that there appears to be no way to find out why. As you say, until that time we are all just flying ticking time bombs.

DJI really needs to raise it's game and start communicating with it users. But I don't think this issue is specific to DJI or to the use of GPS. If I had to guess I'd say that your comment about the airbase is the most significant. From everything I've read over the years about these incidents it seems that all the usual things we suspect have been ruled out in most cases. But the one thing none of us monitor in real time is radio interference.

The other unknown is of course the flight controller code. Because it's closed source, there is just no way to know if a specific set of circumstances could be causing a software crash/issue. I live for the day when open source controllers surpass DJI performance. I don't think we are too far away from that although open source comes with it's own set of issues as well.

 

[222GR]

Man, I am so sorry to hear of your loss - very un-cool!
Can I ask if you were using any of the "Intelligent" modes? I have seen similar things happen to an APM where it decided to switch modes (apparently) all on it's own when flying in IOC mode.

C

I was concerned about the same thing after the fact that somehow a switch got flipped. I used Home Lock and POI but upon verification my switch for that mode did remain off.

 

[222GR]

I don't have a WKM but I know the NAZA will exit advanced features when it goes below 6 satellites.....so I wonder if the WKM is the same and if the erratic flying you observed was the heli losing and quickly regaining satellites making it repeatedly enter and exit whatever mode you were flying in.....regarding FAILSAFE, it will only work if it has the satellites to stay in that mode.

so, consider it was experiencing loss of its sixth satellite, it would drop from an advanced mode like IOC but shouldn't have lost GPS Mode (essentially position hold), if it choked on the GPS feed and lost all six then it would drop from GPS Mode and be unable to rescue itself with FAILSAFE. But if it choked on the GPS signals, cleared itself and then repeatedly choked and recovered, it might appear as a crazy a$$ dance in the sky helped by your desperate attempts to see some form of control response.

Plausible?

I read that WKM is setup to do this as well but i noticed no difference in flight performance if it did happen. The iOSD data shows that it switched to ATTI 3 times during the flight, once almost immediately after takeoff which perplexes me. Then twice very very briefly during the meltdown. The data also shows it flipping into Waypoint Mode near the end whatever that is. I don't have the downlink to utilize the waypoints so I think that's just where it went craziest.
The auto switch to ATTI in the beginning of the doesn't align with any of the other recorded flight data so I'm not for certain its trustworthy. Your choking and recovering theory sounds reasonable for sure. I shoudl see more rapid changes in the data from GPS to ATTI too and it's just not there.
Anything is plausible Bartman. I can only say it's dance seemed consistent with itself and not necesarily impacted by my inputs as well but it's very hard to say. It's altitude increase, fighting against me as I'm trying to bringing throttle down too was a weird one. I only killed throttle completely after the aircraft was gone (down) and far beyond recoverable.

 

[Bartman]

wouldn't increasing altitude be consistent with a failsafe actuation? at least if it was below the altitude it would fly the failsafe at when the failsafe triggered

does a GPS system really need 6 satellites to function? why have these modes (especially failsafe) unavailable when satellites go below 6? i could see three maybe but six??

i also wonder if these units have lower than necessary internal temperature tolerance. i wonder if a lot of the problems would go away if the circuitry were removed from the cases and allowed access to ambient airflow. crazy behavior from electronics can certainly be attributed to high circuit temperatures as was mentioned earlier

 

[222GR]

wouldn't increasing altitude be consistent with a failsafe actuation? at least if it was below the altitude it would fly the failsafe at when the failsafe triggered

does a GPS system really need 6 satellites to function? why have these modes (especially failsafe) unavailable when satellites go below 6? i could see three maybe but six??

i also wonder if these units have lower than necessary internal temperature tolerance. i wonder if a lot of the problems would go away if the circuitry were removed from the cases and allowed access to ambient airflow. crazy behavior from electronics can certainly be attributed to high circuit temperatures as was mentioned earlier

I deactivated Failsafe once it was determined un-useful. The Altitude increases came after and happened like 3 times before it departed.
I agree with your comment on Failsafe being GPS dependant. I'm sure it's necessary but 3 would be more reasonable. I would be ok with CLOSE TO HOME mode

 

[Bartman]

maybe a useful mode would be Failsafe-Failsafe....if it senses a failsafe actuation it that it doesn't complete it should begin a descent and land wherever it is at some moderate rate of descent. Failsafe being actuated at a distance though where the pilot can't tell if the LED is indicating GPS problems doesn't seem like a very reliable failsafe or something a pilot should feel comfortable depending on.

 

[Kari]

How did you deactivate failsafe? If i remember right you also need to switch mode to manual (or atti) and back for deactivating it. Only switching failsafe off in switch does not necessarily deactivate it. In this kind of odd behaviour in flight should always switch to atti or manual so you can clear possible false gps information. I like to keep things as simple as possible and dont use any iosd or datalinks. Just because the more there is gadgets onboard, more there is places for failure.

 

[222GR]

How did you deactivate failsafe? If i remember right you also need to switch mode to manual (or atti) and back for deactivating it. Only switching failsafe off in switch does not necessarily deactivate it. In this kind of odd behaviour in flight should always switch to atti or manual so you can clear possible false gps information. I like to keep things as simple as possible and dont use any iosd or datalinks. Just because the more there is gadgets onboard, more there is places for failure.

You know what Kari, that's a good point I didn't think about that.
I'll have to try it with my 550 again to verify. I'd have sworn that disengaging gives you back control in whatever flight mode you were in previously.

When I flipped my failsafe switch, the aircraft actually did level off but it was the flight in the wrong direction that freaked me out. IF GPS was good it would have stopped, climbed, and came back.
It didn't stop and i was afraid to let it go to far so I disengaged the switch which ceased the wrong direction flight and seemed to put me right back into GPS Mode, toilet bowl, no control.
There was an obvious difference in flight characteristics between failsafe engaged and off again but I won't rule out that a bad assumption was made.

The hindsight of the situation is what kills me. In the heat of the moment it wasn't instinctual to flip to ATTI or Manual, especially since it wasn't obvious to me I had a GPS issue.
It was instinctual to flip FAILSAFE. When FAILSAFE failed for obvious reasons now seen, I'm left with fighting an out of control aircraft. It really doesn't give you a lot of time to assess the situation.
Crappy thing is I'm a proficient ATTI and Manual pilot, it just wasn't second nature enough in an emergency
If we could safely simulate compass errors in GPS mode, training oneself to immediatly go to ATTI or Manual would be best to save precious seconds of hysteria.
Failsafe is only really for loss of transmitter signal if I read that right but it seems like an easy crutch or get out of jail free card that we all want to use to get out of trouble. It obviously wasn't designed to get us out of GPS flight mode trouble.
Could I have saved it in ATTI or MANUAL..... it's impossible to me to say yes but it's the only option for me if and when i rebuild.

This has given me many a sleepless night.

Moral of the story: If FAILSAFE doesn't do what it's supposed to, you have a GPS problem and you better switch to ATTI or Manual to stand a chance of Survival (maybe)
And trust me guys, when something first goes wacky, it isn't totally obvious there's a problem at least in this situation and you think, "Oh that was odd" and seconds are lost.
As I was landing, the first time it went left as I was pulling aft i actually just stopped, hovered, and brought it back to the right like normal and continued backwards for a few seconds until it went left again and then wouldn't stop with centered sticks. Thats when I knew i MIGHT have a problem but ok, just relax and control it (more seconds lost)
wow, its' really not responding to me at all is it.... Failsafe. WHOA WHATS UP?!?!. That's finally when I knew i positively had a problem that escalated fast from there.
Can you envision how the events transpire and you aren't totally all there yet like "This is a big deal!" until its possibly too late?

Still, I really wish there was a way to know what would cause such an error in the first place and avoid the circumstances all together. Hence I'll forever have a hard time having faith in GPS hold mode and you all should as well.

 

[sk8brd]

222gr- was the home point recorded prior too take off? reports like this make me want to rip the gps puck out permanently. i fly with one finger on my mode switch at all time incase of surprises but mostly fly atti. i read reports that even in atti there is compass data being used in flight and flicking into manual is your safest bet when things get wild...sorry to hear about your rig-total bummer.

 

[222GR]

Yeah my home point recorded ok according to the LED.
My failsafe switch and mode switch are right there at my index finger. My finger sits right in between to block accidental engagement and to be quick to FAILSAFE. From now on I'll be quick to ATTI or MANUAL first and keep my fingers crossed.

I don't want to bash GPS, i just don't want to see people depend on it as we all know many who do. I typically fly ATTI a lot too, just this one day, i wanted to grab a couple quick pics and I trusted it and it bit me. It can bite anybody at anytime truly.

 

[sk8brd]

yeah totally hear ya..were any white flashes visible on led..just trying troubleshoot. was the imu mounted on frame or were you using that "upgraded" imu mounting plate on the landing gear. it seemed in past reports like the flip of death deal that vibes had a lot to do it although you can never really be sure as dji never explains anything just provides "updates"