Hello lovely forum,

so i just posted this in the radio category, but i thought, this might indeed fit here better.
Now about the post: so today i had an interesting experience. I flew my drone (i am pretty new to this hobby, it was maybe my 40th flight or something) like 200m horizontally and 100 meters vertically away from me. Connection was super, even for 5.8 Ghz Dji, i had 50Mbps, the crossfire (250mw) signal was also fine throughout the event. Now, very casually, about 2 minutes into the flight, the drone seems to have stopped giving any kind of throttle. It was still armed, the motors spun and the onboard recording of the 03 continued, but it dropped. Neither GPS rescue, nor Angle mode or any stick input changed the drones behavior. it just dropped. This is especially weird, because at r×_loss, failsafe should have activated, and if it did not failsafe, why did it drop at all? This is the basic question of this post. Because i landed on solid concrete, i destroyed a battery, 3 motors, and because of my dumbness to try and boot the drone without a smokestopper after the event an ESC. Wow. that was about 200€ worth of stuff. 

The real question is: has anyone got a clue, what happened? The problem is, i haven’t got goggle DVR recordings, because the SD-card was full and i didn’t bother to empty it for a last flight.

Also interesting is, the  Current reading, after the accident, said, while disarmed, 100A. Now, a possibility would be a broken ESC? Another possibility i thought of, is that my ESC to FC connector was not properly secured, which may have cut off the Motor lines, but have left Energy flowing through sill connected pins. I think this could be, because this was the case after the crash, however, i cannot say if the loose connection on the fist hand.

I would love to have any input, especially as i already ordered all my parts for a 6“ long-ranger, and i really do not want this to happen there again.

PS: I am using a tango 2, dynamic power turned off. In addition, i think, in the past i have had some micro failsafe, but as a result of very low experience, i am not sure if it was as just me pushing the throttle a little too hard. 

There are too many things that this could be to give you a definitive answer, especially without video.

If it just started lowering itself to the ground, you could have ran your battery down too far.

If it tumbled its way down, it could have been have been a desync, a dead esc, a connection that came loose (wire or plug), a motor failure (burnout or catastrophic bearing failure), a failure on the flight controller, or something else.

Those are some of the possibilities for the initial cause- but as you found out, more damage happened when it hit the cement. I don’t think you’ll really be able to determine if, for example, a thing that is burnt out caused the crash, or if that thing burnt out because of the crash when a wire came loose on impact and shorted something out.

Hello Lemonyleprosy,
it definitely needs to have been a failure within the aircraft. The battery was near full, Connection was good, at least as i can remember being reported in the goggles.
Although i cannot help with a DVR-Video, here is an onboard recording of what happened.

https://we.tl/t-Ph2ZOIW3Jl

Hope this helps.

I primarily view this forum on my phone, so I won’t be able to view that unless you upload it to YouTube or similar, but even after viewing it, it’s unlikely that I’ll be able to say, “it was this”. It would just be, “it could be any of these things”, so I don’t know how helpful that would be.

I didn't realise you had posted the same question in two different threads. I put an answer in your other thread. I will copy and paste the same again below.

It could have possibly been some kind of brownout with one of the voltage regulators but it's difficult to say. Do you have a blackbox log of the flight? That can sometimes help to shed some light at to what happened when you end up getting an unexpected incident during a flight.

Hello, it’s me again.
No, sadly i have blackbox logging turned off. Should i just leave it on?
Here’s the video on YT:
Hope this brings more light into the darkness.
Thank you for your time.

It looks to me like GPS Rescue kicked in either by it being tiggered manually or from a failsafe. That is why it would have done an immediate 180 degree yaw towards what it believed was the home point. How many satellites did you have showing? If GPS Rescue detects any anomalies or fails any sanity checks (i.e. it doesn't have enough satellites locked to determine where to start flying back to) it will just disarm the quad and drop to the ground for safety reasons so it doesn't have a flyaway. From the footage it looks likely to me that is what happened.

(30-Jun-2023, 11:24 PM)SnowLeopardFPV Wrote: It looks to me like GPS Rescue kicked in either by it being tiggered manually or from a failsafe. That is why it would have done an immediate 180 degree yaw towards what it believed was the home point. How many satellites did you have showing? If GPS Rescue detects any anomalies or fails any sanity checks (i.e. it doesn't have enough satellites locked to determine where to start flying back to) it will just disarm the quad and drop to the ground for safety reasons so it doesn't have a flyaway. From the footage it looks likely to me that is what happened.

As far as i can remember, i had more than 10 satelites, that should be more than enogh. In addition, i dont think this was a failsafe case, because it is set to first slowly gain altitude for 1.5 sec, then return to home, and, as far as i remeber, the turnaround was my input, to check video signal when the antenna is pointing away rom me. It seems like, when turned back, it just randomly failed.

Unfortunately without a blackbox log to give you some clues it's just going to be a guessing game. At least with a log you would be able to see if any of the modes or a failsafe had been triggered, and/or if the FC was unsuccessfully trying to command 100% throttle to any of the motors when it dropped out of the sky which would indicate a power or signal failure to those particular motors.

I tend to leave blackbox logging permanently enabled on my quads that have an SD Card slot (which has virtually unlimited logging space). For quads which only have a flash data chip for logging it's a bit more of a pain because you can usually only log a few flights before it fills up after which you then have to manually erase the flash memory either from Betaflight Configurator or via a switch on your transmitter which can take > 30 seconds to do. At least if you have a log of every flight, if anything unexpected happens during the flight you then have some data you can analyse afterwards.

It looks to me like there was an issue with your front left motor, like it was slowing down/stopping. That’d point to a desync, esc, or motor problem- but that could just be the frame rate playing tricks on me.

If it was a proper desync, I would expect it to go into a more violent tumble. As Snow said, it looks more like it just disarmed mid air.