Help with iFlight nazgul5 V2 death roll?

[itsniklavs]

Hey, so i just got the iflight nazgul5 v2 4S BNF quad. Set it up, tried flying it for a few seconds and it just started literally spinning and dipped mid air.
I couldnt understand what had happened so i tried googling it and looking on youtube and everything, i found out that this is called a "death roll" when the motors "desync" i guess(??)
Thank god a friend of mine was filming my first flight - https://files.fm/u/yg6cq966m if you zoom in super close it looks like it starts rolling mid air but i cant seem to understand which side/which motor is to blame. But when i take off the props and power it up at home, the motors seem to work perfectly fine when i increase/decrease the throttle.

Oh and a general question - should the motors\flight controller/VTX get hot when a battery has been plugged in even when its standing still for some time (5-10 min) or e.g. the motors are spinning with no propellers on?

ANY help will be greatly appreciated since im kinda new to this hobby and theres A LOT to learn Smile

p.s. if there are any settings/info i should check/post here please feel free to tell me! Trying to learn as much as i can.

Thanks!

 

[wafflejock]

Hiya, thanks for sharing the vid helps with figuring out or at least making some educated guesses at what's going on.

Regarding motor desync while possible this isn't a very common problem, more often a signal wire from the FC to the ESC or the ESC itself has some issue or could even be a loose prop nut that stops one corner from being able to apply thrust (or something simple as a zip tie or battery wire getting in the way of a prop).

Because of the flying off the snow and mentioning that the gear runs hot I am suspect that some snow could have melted and the water could have shorted some connection shortly after the take off there. I would try it out again somewhere dry and just fly line of sight at first (watch the quad no goggles on and keep it in "angle mode" so it mostly stays level and can just practice hovering it a safe distance away from yourself). Usually watching/testing things like this line of sight (LOS) can help determine what's happening or what it is you do with the sticks that throws it into the bad place . From there can maybe get another vid of that and just thoroughly test each ESC as you did already on the bench but can do it on the ground with props on and just use right stick only so no throttle input and tip the quad left right forward back (not to far to not scrape up you props). If under load things are okay on the ground should be good for that LOS test flight.

In general a VTX will run hot because it is a transmitter and so usually is basically a transistor or other amplifier component that boosts a signal before passing it along to an antenna, if you have no antenna attached or the connection is broken the VTX will still be amplifying power and not be transmitting any of it out as radio waves really so will get hotter than if antenna on it but they always run pretty hot. You do usually want to keep the VTX off if bench testing for extensive periods if you can so it's not just cooking itself, the airflow from flying helps cool it.

The FC and ESCs should stay cool while not operating same with motors. Motors running loaded (with props on or resistance to spin like a finger rub applied) then it will use more torque/amps to try to keep the speed going and overcome the load. The extra current means extra heat in both the motors and ESC. If VTX is near those other PCBs it can heat them up too but usually the FC itself doesn't run terribly hot in my experience.

If you can get Blackbox logs from your quad that can be helpful to diagnose issues as well, sometimes will see actual faults in the logs when checking out in blackbox log viewer app (separate from betaflight configurator but similar).

 

[Dugdog47]

I've had death roll on 2 kwads and both reasons turned out to be esc related. One was because of underpowered escs and the other was because of my bad soldering (luckily I've gotten better since then lol)

Check all solder joints on the escs, I'm willing to bet you have a dry joint.

 

[itsniklavs]

Hiya, thanks for sharing the vid helps with figuring out or at least making some educated guesses at what's going on.

Regarding motor desync while possible this isn't a very common problem, more often a signal wire from the FC to the ESC or the ESC itself has some issue or could even be a loose prop nut that stops one corner from being able to apply thrust (or something simple as a zip tie or battery wire getting in the way of a prop).

Because of the flying off the snow and mentioning that the gear runs hot I am suspect that some snow could have melted and the water could have shorted some connection shortly after the take off there. I would try it out again somewhere dry and just fly line of sight at first (watch the quad no goggles on and keep it in "angle mode" so it mostly stays level and can just practice hovering it a safe distance away from yourself). Usually watching/testing things like this line of sight (LOS) can help determine what's happening or what it is you do with the sticks that throws it into the bad place . From there can maybe get another vid of that and just thoroughly test each ESC as you did already on the bench but can do it on the ground with props on and just use right stick only so no throttle input and tip the quad left right forward back (not to far to not scrape up you props). If under load things are okay on the ground should be good for that LOS test flight.

In general a VTX will run hot because it is a transmitter and so usually is basically a transistor or other amplifier component that boosts a signal before passing it along to an antenna, if you have no antenna attached or the connection is broken the VTX will still be amplifying power and not be transmitting any of it out as radio waves really so will get hotter than if antenna on it but they always run pretty hot. You do usually want to keep the VTX off if bench testing for extensive periods if you can so it's not just cooking itself, the airflow from flying helps cool it.

The FC and ESCs should stay cool while not operating same with motors. Motors running loaded (with props on or resistance to spin like a finger rub applied) then it will use more torque/amps to try to keep the speed going and overcome the load. The extra current means extra heat in both the motors and ESC. If VTX is near those other PCBs it can heat them up too but usually the FC itself doesn't run terribly hot in my experience.

If you can get Blackbox logs from your quad that can be helpful to diagnose issues as well, sometimes will see actual faults in the logs when checking out in blackbox log viewer app (separate from betaflight configurator but similar).

Hey, huge thank you for taking the time and for a very informative response!
As for the testing, i will sure go out in the next couple of days and try testing it with props on and on the ground, little adjustments to each side without throttle. And then the LOS procedure too.

As for the blackbox, i had never ever touched it so yesterday i just went and exported everything thats on it - Blackbox file download
It gave me 77 different flight logs, the rest of them are little 1-5 second tests of me just not knowing what i do and doing some stick movement with no propellers and on my desk so please ignore those, as for the crash that im looking for I assume its the last log on the list since that is the longest flight i have got there.
But just to be sure, is there any way of telling on what date/time each log has been created? I noticed that the 8mb blackbox was full when i exported, so maybe it has never even recorder the crash.
If im able to find the date/time of it i can perfectly find the one i need, since there are maybe a few like 9 or 18 second logs im really not sure which one is the right one.
If there are no options on checking the date of recording, are you able to see which flight it may have been just by looking at it + the video i have provided?

Im pretty sure its the last log (29sec long), but again i dont really know since i dont understand the blackbox files and they are all just lines and curves and stuff to me

Thank you for everything and anything!

 

[itsniklavs]

I've had death roll on 2 kwads and both reasons turned out to be esc related. One was because of underpowered escs and the other was because of my bad soldering (luckily I've gotten better since then lol)

Check all solder joints on the escs, I'm willing to bet you have a dry joint.

Thank you for the quick response!
As for the soldering, im still learning on that one, since i bought a BNF quad i had nothing that needed to be built, i think the Nazgul5's are pretty solid out of the box and esc shouldn't bethe issue but you never know i guess.
So should i practise my soldering and redo all the cables that are going from my motor to the ESC(?) or like any specific cable that needs to be checked out?

 

[wafflejock]

Hey will let ya know when I have a chance to grab the logs and try looking them over but in general I just wipe out the black box log and make sure it's turned on to start recording logs (sounds like already good there) but might be worth saving current ones and wiping them out from the quad so it just has new logs going forward (usually I just do a few test runs and dump the files then clear the black box memory so can get more fresh logs)

 

[wafflejock]

So I did finally look at the logs here and unfortunately on the crashed one not seeing the disarm at the end or any sort of thing happen at the end that would indicate the failure. Best I can say is the FC power cycled for some reason otherwise the log shouldn't just cut off (let me know if you see the same maybe I need to update my version of betaflight log viewer)

 

[itsniklavs]

Hey will let ya know when I have a chance to grab the logs and try looking them over but in general I just wipe out the black box log and make sure it's turned on to start recording logs (sounds like already good there) but might be worth saving current ones and wiping them out from the quad so it just has new logs going forward (usually I just do a few test runs and dump the files then clear the black box memory so can get more fresh logs)

Hi, thank u for the answer!
As for blackbox - i notice that it really fills up the 8mb super fast right? Are there any recommended settings or anything i should put the blackbox to?

 

[itsniklavs]

So I did finally look at the logs here and unfortunately on the crashed one not seeing the disarm at the end or any sort of thing happen at the end that would indicate the failure. Best I can say is the FC power cycled for some reason otherwise the log shouldn't just cut off (let me know if you see the same maybe I need to update my version of betaflight log viewer)

Yes sir, i saw that it doesnt have the disarm set, but i think it was because of the crash. Am i seeing it correctly that at the end of the log it made one motor spin to 100% right? Idk i will try flying again in level mode and check for any suspicious stuff but so far so good, will give updates if anything happens, thank you for everything!

 

[wafflejock]

Yah the FCs with onboard flash do tend to be really small hence the habit of clearing it out also just easier to find which log was which flight doing it from a clean slate. Some FCs have a micro sd card slot usually used for extra long black box logging, can get like a 4GB micro SD on the cheap and not worry so much about clearing logs to get space. There was some weird data in that log but wonder if it got corrupted if power cut or dipped to the FC could have been something as simple as loose xt-60 connection or something (if battery ejected during crash hard to say though and still just a guess)

 

[wafflejock]

Generally speaking the flight logs will show the events whenever something like ARM/DISARM or RXLOSS or anything like that occurs but if something was shorting or otherwise under powered then corrupted logs are definitely a possibility unfortunately (despite the name our blackbox in this case is just as exposed as the rest of the FC to the elements).