An 'almost' flyaway... or not?

[Richlizard]

Hi all.

Having now read dozens of stories of ';flyaways';, I have come to the conclusion that actually flyaway has almost become the excuse word for bad airmanship. I myself thought I had one when I lost my phantom a few months ago, but had to concede to the experts that actually I probably lost visual while over a factory building and brought the rest on myself on what was probably a day too windy for the craft.

So I am half expecting this morning';s activities to be shot down in flames as an error on my part, but rather than hope it doesn';t happen again, I want to know what, if anything, I did wrong and would appreciate advice. I will answer any questions as honest as I can. Feel free to get stuck in.

So with a minor window of mild weather, I took the opportunity to take out my F550 to film some flood areas in the countryside, mostly roads. I did most of my checks yesterday but double checked everything again this morning. I also recalibrated the compass as like most of us, having not flown for so long I just thought it best.

I even took along an observer, perhaps feeling a little apprehensive after not flying for so long and recently changing my two red arms to black and re-soldering the battery connections as they weren';t perfect.

First area: no problems at all.

Second area: Took off and while attempting to head direct to the tree area where I wanted to film, I felt that my ';forwards'; direction was more a 45 degree direction (GPS mode). I didn';t like it, so thought the prudent thing would be to bring it down and start all over. Taking off to head height, the 550 seemed to hover perfectly so I took it over the treeline and headed towards the flooded area. As I approached where I wanted to film, I noticed the GPS wasn';t holding position. In fact, it seemed to be moving away even though the wind was light. So I went into Atti and it seemed everything was fine. Perhaps I was just imagining it?

Moving around a little, I stopped to hover over the area and adjusted the gimbal to point more down than it was. Flop... the gimbal failed. Now the last time I was flying regularly, the gimbal (Zenmuse h3-2d) failed each time, but it was windy. The supplier (byod) told me it is designed to ';stall'; if you fly too fast, creating an angle that is too steep for the gimbal. I had shown them a video of it on my desk when it stalled. Ref: Zen stall and they told me this was normal behaviour. Even though it does not happen on my friend';s machine with identical setup! But I said I would test again and give them a video of my findings when the weather improves. It didn';t!

Anyway, I am wandering off and this wasn';t that test. This was just to get a few snaps of flooded areas, mostly requested by friends.

Well as soon as the gimbal went, viewing it on my monitor, I knew I would have to wait up to 30 seconds for it to right itself. I put it into GPS mode to hover and told my observer what had happened. As we waited for it to right itself, it suddenly took off like a speeding bullet through the sky in a westward direction from us so we saw the full speed of it. It was seriously flying, possibly 50mph if that is even possible. I was not touching any of the controls. I immediately flicked to Atti to save it, but it had gone. My stomach sank as it shot off behind trees and hundreds of yards away. More worryingly, towards a main road!! I ';knew'; I had lost it, but what was the extent of this going to be.

Last resort: The big red button. I switched on failsafe. To my absolute surprise and major relief, it just turned towards me and flew directly at me. I had GPS back on before the red button flick and it was heading fast directly towards me... but NOT where it took off from. As it got closer, I had of course lost all confidence in GPS, so switched to ATTI and landed it safely in my arms.

We got back to the van and checked absolutely everything. Pulled it to pieces and everything was as it should be. We could find nothing at all wrong. Checked it all in the Naza software and all seemed healthy there too. If I had never flown again, I do not know what I could have done to change things.

So we took the decision to go on to the final areas. Taking it easy, I took off and only went up ten metres at a time. It was as solid as could be. I didn';t keep it up too long as I didn';t want to tempt fate, but it flew and hovered exactly how it should.

The daft thing is that the roads (closed) we wanted to film flooded look exactly the same from the air as they would if they were not flooded!

But as you can imagine, my confidence has been pretty much shattered. My aircraft was just hovering, very little wind, 9 GPS sats showing on my iOSD, in the middle of nowhere with interference... and it decided to make like an asteroid and shoot.

I am close to gaining my licence. Imagine if this was a commercial job? I cannot afford for this to happen again, but cannot understand why it did.

Anyone got any obvious advice please? I know this isn';t Facebook, but please keep abuse to a minimum. Feel bad enough as it is.

Cheers

[Jumpy07]

Richard,

What version of firmware are you using in the Zenmuse ?.. reason I ask is that the latest version does not go into "stall" mode as easily..  it copes with higher load on the motors..

[attachimg=1]

Also the different rubber bobbins that come with the Zenmuse have different hardness.. and allow for different angles.. so make sure you have the widest ones... think 40deg the black ones allow for widest range..

[Richlizard]

Hi Craig.

I went through all the Zenmuse stuff with Martin at BYOD who seems to be the mutts with everything RC. I have the black ones on, if that helps. I tried the white ones and it made little difference, but as they were so lightweight I didn';t feel comfortable with them and switched back to the black ones.

Strangely, DJI say not to use any on the 550, but I could find no way to attach the gimbal without them lol.

When the weather clears and I get my confidence back, I will take some footage of when it happens, but today';s incident was definitely nothing to do with angles as it was barely moving and very little wind around.

Any ideas on the asteroid incident here?

[Jumpy07]

Not sure Richard.. would check your failsafe settings.. make sure the assistance shows failsafe when you switch your TX off.. and check what the other sticks do..

Only thing I can think of is it went into failsafe (RX Failsafe) and didn';t trigger failsafe on the Naza... (if that makes sense)

[Richlizard]

I did check all these things after putting on two new arms recently and doing the soldering. I can';t say 100%, but I check these almost every time I go out now since the phantom issue.

I just realised, I haven';t flown since I installed a canbus hub recently due to having one canbus too many (btu added). I would have thought that either works or it doesn';t, but maybe adding the BTU and Hub is just one thing too many.

Maybe once I have sorted gains out with the BTU, I should remove the BTU and Hub and stick with just the iOSD and PMU on canbus.

[Jumpy07]

I would recalibrate your TX and check what happens in assistant when you switch your TX off..

The assistant should show failsafe when your TX is off..   not just when you flick the failsafe switch.

[dyls]

It doesn';t sound like the fail safe was the problem.
The craft came back to him when he switched the fail safe on.
He says it was coming right to him and he then switched to atti mode to land it.

The flying away for no reason is his problem.
I have heard of other Naza';s doing a similar thing.
Although I don';t believe they got to the bottom of the problem either.

Good luck

[n506]

Well, to state the obvious, in order for it to stop hovering and decide to fly away, it has to either receive an instruction to do so, or it has to think it';s doing the right thing on its own. Thinking it';s doing the right thing on its own is very hard to do anything about, if there is indeed any software issue with the naza, but receiving an instruction to do so is something you can check.

It sounds like full throttle engaged, but it lost gps control. This could be receiver failsafes not being correct and your transmitter lost contact with your receiver (for whatever reason) and had a failsafe of perhaps atti mode on your selection switch, combined with full throttle (easy to do if the throttle should be reversed to knock to zero, but hasn';t been). This would cause it to fire upwards, staying level, but as soon as it hit higher level winds, it would just go with them (generally 40-50 feet up you get a lot heavier winds). And then you messed about with the controls but got no response, because you';d lost your signal, but by chance the signal was reestablished (when a source of interference stopped?) and the fact you';d hit the failsafe button caused it to jump immediately to that command and come home?

That solution sounds slightly more likely than a wrong decision to move by the naza, because I';m not sure it would quite go off like the bat out of hell that you describe if it decided to move to another location, and also, I doubt it would start to fly home if it was wrongly understanding where it should be?

I think you want to take off your props and connect to the naza control software and check what absolutely happens when your transmitter is switched off... just in case that';s what it is. If it isn';t that, the scarier problem is that it doesn';t sound like a problem that could have been within your control!

[Richlizard]

Thanks n506.

I will check tomorrow what happens when transmitter is switched off.

As for what you described above being the ';solution';... I think I will need a really fresh head for my brain to see that as a ';solution'; 

Will let you know tomorrow. 

[flybywire]

Hm, i can only echo what Craig had said about firmware.  I have a 550 with naza 2, canbus, iosd mini, bt unit & 2.4 datalink, so the full monty!  I have the latest firmware for all the modules, and have not experienced any issue.
I did have one similar incident to you with a naza v1, in that i was flying forwards, when suddenly it pitched up and went wot, whilst i lost pitch and roll.  I still had yaw & throttle, but hit a tree before i could really do much.  It did dent my confidence at the time, but i checked it over and could find no fault, i still use that quad, but have never had a repeat since, and have every confidence in it.  I put it down to either interference or radio failure, because of the loss of control.
What radio are you using?  Are you using same radio for your phantom?
Do you have telemetry for analysing dropped frames etc?

Andy

[n506]

Well if the solution is something you can fix that';s brilliant. The scary blackbox code is what has always scared me hence I have a naza but no gps unit fitted. But they';re one of the most popular flight controllers ever sold so it';s likely always that a problem is pilot based in the majority of occasions or else they';d be flying off in all directions all the time.

[Richlizard]

What radio are you using?  Are you using same radio for your phantom?
Do you have telemetry for analysing dropped frames etc?

Andy

I use a Futaba T8J and the phantom has the same receiver, yes.

[flybywire]

I use a Futaba T8J and the phantom has the same receiver, yes.

I assume you mean the same model of Rx, not the ';actual'; same physical Rx!?
Does it have a satellite Rx? 

[Richlizard]

I assume you mean the same model of Rx, not the ';actual'; same physical Rx!?
Does it have a satellite Rx?

It has the same model of receiver, correct. One transmitter controls two receivers. The phantom was at home miles away with its own receiver.

Not sure what your last question is asking.

[dyls]

A satellite RX is a 2nd RX that plugs into the first RX to give more "power".
I don';t believe Futaba need/use them.

Good luck

[Richlizard]

Oh i see.

No, I don';t have one of those and have never gone out of range. In fact, I would estimate I was filming only approx 100m from where we were stood.

I have flown over 400m away in the past.

So frustrating.

[n506]

I think the concern for me is not that you could have lost connection (radio comms is always at risk of interference here and there) but that if loss of comms was the cause then it should have failsafed safely back to you... but it didn';t right off which does make me suspicious that your receiver has a default failsafe which isn';t set to enable the naza failsafe, and may worse still be stuck to full throttle which is very dangerous.

If not, you have a mystery on your hands as to the unusual behaviour as I can';t think of any other reasonable explanation.

[dyls]

Ah ha, n506 now I';m with ya.
Your spot on, I';m with you.

On my Futaba 6ex TX I can';t turn off my failsafe.
I can only turn the throttle down but now off.
It is something that would conflict with the flight controllers failsafe setting.

Jumpy makes the same point earlier, I missed the point there as well.
I';m often in a state of ....

Good luck

[flybywire]

As n506 has mentioned, please check your failsafe setup in the Naza assistant, see what happens when u turn off your Tx.  The throttle should be set at around 55%, which in ';normal'; circumstances is just hovering.

[Richlizard]

Flybywire, do you mean set in Naza at around 55% or set on the failsafe page in the T8J?

Anyway, most want to see what happens when I switch my transmitter off... so here it is...

[attachimg=1]

[n506]

That was my bigger worry... I think you have a mystery on your hands. If that is what happens when you lose signal, then I have no explanation of why it should take off on its own like you describe. Do you have an i-osd that you could record footage from? If so, it would indicate loss of satellites or such like in a future incident.

Cut the bl**dy gps wire I think, although I do have a control freak attitude to my gear.

[Richlizard]

I have iosd but no, can';t record what it says on the screen.

I was taking images at the time 2 seconds apart and looking at the images, the whole thing lasted maybe 20 seconds before I gained control. That is a long time when it is going full blast away from you.

I thought it might be an idea to show one of the images before it happened as you can see there is very little to cause any interference.

Desperately thinking aloud, is there a chance the Zenmuse stall somehow triggered something to go wrong? I have no idea what that something could be mind...

[n506]

Can';t say it looks like the sort of place that you';re liable to get interference right enough, but always hard to say for sure. I take it you know the basic stuff like keeping the antenna on the transmitter at right angles to the direction of the craft? Beyond stuff like that, perhaps an issue with your transmitter?

Similarly it could be an issue with any part of your setup from transmitter/receiver through to flight controller. Your zenmuse is connected to your flight controller in this case, so it could be a possibility (in a way most brushless gimbals could never be), but I can';t see the flight controller being that "hooked into" the zenmuse as to cause that kind of issue.

Right off, I can';t really think of any good reason (one that you can easily fix) as to why it should have acted the way it did. You';ve covered the only possibility I could think of right off. It sounds one of those nasty intermittent problems that can be so hard to track down. I remember when I first bought a naza v2 fc, it had an issue out the box where it would dump full power through the motors and take off like crazy for a second anywhere up to about 5 minutes into a flight. Of course, I';d instinctively kill power, and it';d then drop like a stone. It caused a lot of frustration trying to figure it out, but the fix ended up being a complete factory reset and redoing all the settings, and it';s never done it again. So if there is some kind of bug in the system, perhaps a factory reset could be worth a try at least. It';s a horrible situation, because there';s nothing worse than fearing that your craft could take off like crazy at any given second, especially if you';re taking on jobs with it!

[Richlizard]

Thanks for the reply again. Answers below.

Can';t say it looks like the sort of place that you';re liable to get interference right enough, but always hard to say for sure. I take it you know the basic stuff like keeping the antenna on the transmitter at right angles to the direction of the craft? Beyond stuff like that, perhaps an issue with your transmitter?

I didn';t know this, no. But my transmitter doesn';t have an antenna - Futaba T8J. The receiver inside has two wires that are placed at right angles.

It caused a lot of frustration trying to figure it out, but the fix ended up being a complete factory reset and redoing all the settings, and it';s never done it again. So if there is some kind of bug in the system, perhaps a factory reset could be worth a try at least.

I';ll try anything once. Do you mean resetting the Naza? Because I did this when trying to sort out the gimbal issue... which has definitely not been solved as it now ';stalls'; when just hovering as has since been proven. Probably worth a separate thread so this main issue doesn';t get sidetracked.

[n506]

You shouldn';t have any issue with your transmitter then. In the case of a normal transmitter, if you were to point the aerial directly towards the craft, you';d have virtually no signal reaching the craft, compared with having it at right angles to the craft. It';s sort of a deadzone in the aerial transmission.

I went to the Tools section in the naza assistant software and did a "Restore default settings" after making a note of the settings. I then re-entered all the settings. No explanation as to why, but the identical settings appeared to work correctly after that. I';m not really suggesting it as any kind of fix... rather that it appeared to cure a bug that I couldn';t get rid of any other way, and this may be a similar possibility for you. A bit of "If you don';t know what the problem is, start from the basics".

Sorry I can';t really help you further, but I literally can';t think of any other "pilot controlled" issues that it could be. A very weird one, because I was genuinely expecting something simple like receiver failsafe issues that would cure it. If you do figure it out to a specific problem, write back. It';d be very cool to know what the cause was!

[Richlizard]

The sad thing is that to solve the problem, I would probably need to reproduce the issue... and I really don';t want to do that! 

[n506]

Always the catch-22 of an intermittent problem!

[Gadget Man]

BTU, (Bluetooth), transmits on 2.4Ghz.
I wouldn';t myself consider using Bluetooth if my control reciever was also on 2.4Ghz.

Just a thought..

[Richlizard]

BTU, (Bluetooth), transmits on 2.4Ghz.
I wouldn';t myself consider using Bluetooth if my control reciever was also on 2.4Ghz.

Just a thought..

Are you saying that the equipment recommended and sold by DJI could actually cause their own equipment to fail? Surely if there was an issue, they wouldn';t sell them?

[Gadget Man]

No I am not saying that, not at all