As the topic says: What went wrong?

[Chop]

Hello,
I build my first quadcopter a few weeks ago and also flew it perfectly fine a few times.
But recently a crash made me think "Why the **** did it crash?

To describe the situation:
I was flying on an empty parking place about 3 min when suddenly the quadcopter stopped the motors, falling a few meters down (about 3-4), and then re-starting the motors and luckily self leveling, therefore preventing damage from hitting the ground.

Ok, i landed safely.
No warm battery, ESC or Motor.
Cables looked fine, Controllboard had no "ERROR" or something.
Soldering points also perfectly safe, no problem there.
Everything wired correctly, no cables loose or missing.
The KK also had connection to RX (regarding to the receiver test).
Voltage of the Lipo was still good but i don't remember the exact voltage.
The FPV system was alive the whole time so thats ok at least!

So, everything checked, no problems found, next flight.
Same thing as first flight, this time the quad did not restart the motors and hit the ground.
One broken arm and a few props had to be replaced.

Well, i coulnd't land safely but the "after crash analysing" went the same, nothing hot/warm, missing or loose.

Oh and during both "falls" i had no controll over the quad, no connection?

Possible theories for the crash:
- interference, wifi of nearby houses? ~50m
- metal lamp pole blocking the signal?
- Bad tx, therefore low range, early cutoff? <80m seems fairly low...
- cheap esc/ low quality, maybe there a cutoff?
- low c rate Lipo causing voltage drop and bringing ESCs to stop?

And finally, the exact components used:
- HQ 6045 carbon reinforced props
- Tiger Motors MN2206 2000kv
- Hobbyking YEP! ESCs 18A (the only ones left at the time and pretty cheap aswell, so i took them)
- Turnigy nanotech 1300mah 25c
- KK 2.1.5
- Emax 250 Pro Frame
- Flysky ct6-b

FPV
- Immersion RC -> 5.8Ghz, 25mw

That should be everything told. I tried to make it as detailed as possible because i would love to fpv all day long and the quad is currently grounded till the problem is solved. *hope for a solution*



(Maybe it's me just buying cheapo components or making beginner mistakes again and again, but that's another topic)

Greetings from northern Germany where the weather only leaves a few perfect flying days.

 

[holtneil]

Hi mate what firmware has the KK got on it the hobby king firmware has this cut out problem , reflash with steveis1.8s1pro

 

[Chop]

Jeah it has the standard firmware it came with.

So thats it? Just ordering this little cable to flash the kk?
I will try that and post the results once it arrived...
(it seems too simple to solve the problem o.o but who knows)

And are you sure that it has nothing to do with the ESCs or the transmitter?

 

[holtneil]

Well you can never be 100%, but it is a known fault of the hobby king firmware, to make you crash and when you check the quad it all works
But my gut says firmware when an ESC fails why do all the motors stop 3 will still be working thats why I say firmware shutting the kk off
If it was brown out or signal failing when you plug in the battery the receiver light will not be steady it will be flashing to say its had a brown out or signal loss

 

[Chop]

Well ok that sounds like a good explanation. Unfortunately the USBasp AVR programming thingy is not in stock here in Europe and i dont want to wait either weeks for it to arrive or pay tax for International shipping so i will probably go for a new board since the programming cable would cost ~12€ and a naze is not that much more.
I thought of the naze32 for future expansions like the osd and gps or maybe the cc3d (which has no osd support so i'll probably go for the naze32).
Oh and do you know for wich features the full naze32 instead of the acro is needed?
-OSDoge
-GPS (PH/RTH)

Thanks in advance

 

[Chop]

Ok never mind the question is no more relevant..

still thanks for the fast and informative answers!

 

[holtneil]

Hi Chop so have you gone for the nase32 I hope you know it will not work on any DJI or DJI clone frames as the guy who makes the board Hates DJI

 

[Chop]

yeah i heard the naze32 boards triple flip and head straight into the ground if contacted with anything by dji...im pretty happy they implemented that

 

[Chop]

I know this thread is now a bit quiet but i just wanted to say thanks for the support.

I got the naze a week ago or so and changed my flying location and my last few flights went flawless. I think that solved the issue. *happy *
"Cheap and easy could everyone." - Lesson learned!

 

[holtneil]

HI mate sorry been on night work glad its sorted my friend , play safe and happy flying

 

[Chop]

I should not have said that. :/ It happend again but i was lucky and only ~2m high and ~70m away so no damage at all.
But i still wonder what could have happened.
Location is far from any Wi-Fi or telephone antennas and i was standing up for better signal.
I also managed to reproduce a signal loss on a "test setup" but the rx had no light indication after it had signal back so i cant detect if the copter actually had a signal loss. That makes it probably even more complicated.

 

[holtneil]

Hi mate the next time you plug battery in if the receiver flashes it had a brown out, they dont all flash that the time you get it back

 

[GJH105775]

What are your motors pulling also. If they pull near the ESCs you probably have the problem Neil said. The battery could be having too high of current drawn and then a voltage drop, causing a brown out. Usually batteries puff though. Does this happen while your hammering the throttle?
By the voltage being good, it should be higher than the voltage listed on the pack. It could also be voltage cutoff on the ESCs also.

 

[Chop]

I don't have a thing to measure the current but ecalc claims about 13A max. ESCs are 18A.
A voltage drop of about 0.2v - 0.4v while jumping from ~25% to ~60% throttle.
The LiPo can handle up to 50c for a short period of time. 25c is for constant. And no puffing yet.
I had problems with lv detection before and therefore set the ESCs to NiMh so thats sorted.

To get some "try out" solutions, what could be done against brownouts? new lipo, ESCs, rx or even a whole new tx system?

 

[holtneil]

Hi as for a test you can run receiver and FCB off a single battery and flight power for the battery you have been using

 

[Chop]

Hi sry for not replying...

A new Taranis 9XD Plus (this badass was very hard to get here, it feels like i got the last one in europe!!) is on the way aswell as some KISS 18A ESC, a seperate BEC and a small PDB with a integrated BEC.
It will take a few days for the stuff to arrive but i will post any results after the build. If it still crashes then i think my copter has a bad curse on it or sth

 

[Chop]

Ok to refresh this thread i have to say the issue is NOT fixed... I changed basicly every single part on the copter.
- power distribution changed 2 times
- fc changed, powered by seperate bec now
- esc changed, top quality now
- no bullet connectors, everything properly soldered
- rc system changed, no failsafe indication there
- different lipos -> no change

the only thing left are the motors, which have been through a few crashes, including one were i managed to brake a carbon fibre arm...
it flies great but suddenly the motors stop and the copter drops out of the sky like a rock..... not very reliable :/

i bench tested the motors (still on the quad, props off) with the taranis and with cleanflight directly but the random stopping was not reproducable...
it might help to know that the stopping happens at about 4-6 min in flight sometimes more sometimes less...
the naze board should have no problem since even while dropping it provides information for the minimosd
i also tryed fpv and LoS -> still dropping so no interferance there...

can a bad motor (or perhaps more than one) realy cause a complete stop and make the copter drop?

 

[GJH105775]

It could if two phases were shorting, but it would be lost as soon as it started. What about a bad battery?

 

[holtneil]

Hi mate you only need one motor stop and the quad will come down , can you get a single motor just replace the one
A bad battery all motors will stop

 

[Chop]

Thanks,
the lipo...i have tried two different packs of the same kind, both causing crashes and since the voltage is also constant (seen through minimosd, sensed via vbat feature of naze) a lipo failure is unlikely...
i will try to identify if there is a motor problem, maybe contacting phases due to vibration, tomorrow
maybe previos crashes have damaged the motors also...
and would the naze stop the other motors to "correct" if one fails?

im startin to believe someone aims a high power radio signal at my quad all the time making it crash on purpose...haha