Mikrokopter Dropped like a brick from the sky

ctbon

ctbon

Member
Had a bit of a nasty crash and I have no idea what went wrong.

It was flying perfectly and as I was bringing it back to land on my balcony she just just cut her engines and dropped like a stone from about 15 feet in the air. A couple of outriggers were bent and some plastic screws were broken and the battery was ****ed up pretty bad so I won't be using that one anymore. Everything else was fine. I put it upright, disconnected and reconnected the battery to see if it would start and it did. I hooked it up to MK Tools and everything was OK. What might have went wrong?
 

O

ovdt

Member
ctbon said:
Had a bit of a nasty crash and I have no idea what went wrong.

It was flying perfectly and as I was bringing it back to land on my balcony she just just cut her engines and dropped like a stone from about 15 feet in the air. A couple of outriggers were bent and some plastic screws were broken and the battery was ****ed up pretty bad so I won't be using that one anymore. Everything else was fine. I put it upright, disconnected and reconnected the battery to see if it would start and it did. I hooked it up to MK Tools and everything was OK. What might have went wrong?
Click to expand...

Hello ctbon,

I had the same power cut issue a few weeks back: http://www.multirotorforums.com/showthread.php?2106-Several-crashes-some-lessons-learned

Did you have a sd card installed on Navi-ctrl? If so, please upload it we can check that out. (I didn't have it installed so I have to investigate the problem more extensively. For instance, the molex conector between FC and PDB is quite important. You should check out the PDB against I2C errors. )
 

ctbon

ctbon

Member
yeah, I was just reading your thread after I posted this one...I didn't have the SD card installed so I guess it will remain a mystery as everything is checking out ok right now. How could I check the PDB for I2C errors?
 

Droider

Droider

Drone Enthusiast
Eh Up Chris.. ouch.. what was your flight time / battery condition.. it sounds to me you had a power failure.. low voltage may be.. do you have a battery alarm?

Dave
 

ctbon

ctbon

Member
Hi Dave, the battery alarm didn't go off. I don't think it could have been a low voltage issue. I had a full charge and less than 5 minutes of flying with no camera. I was flying very close so I would have heard the alarm. I didn't check the battery because it was mangled from the crash but I'm pretty sure it couldn't have been drained. Also, I easily restarted the copter after the crash and there was no alarm then....just the awful noise of two props grinding against each other due to a bent outrigger :nevreness:
 


C

connexxion

Member
Never ever rely on the molex cable only.

Solder 2 extra connections between the FC and PDB.

Solder a direct connection between C and D on your FC and PDB.Also solder a direct connection between the Fc and power on your PDB.That molex cable is a nasty little thing.
 

Benjamin Rowland

Benjamin Rowland

Member
connexxion said:
Never ever rely on the molex cable only.

Solder 2 extra connections between the FC and PDB.

Solder a direct connection between C and D on your FC and PDB.Also solder a direct connection between the Fc and power on your PDB.That molex cable is a nasty little thing.
Click to expand...

Could you explain this a bit further. I'm new to this. Thanks.
 

C

connexxion

Member
Benjamin,

the little molex connector/cable was ment to keep things wirewise simple.

This is how things used to look like and I just build one this way:http://gallery.mikrokopter.de/main.php/v/tech/CIMG8362_Verkabelung_Vor_Einbau.JPG.html

It feeds the FC,passes the I2C commands and even feeds/connects the buzzer.

The cables it is made of are very stiff and pass all the vibrations to the little connectors.These connectors are not made for what you use them for.

Instead,go the oldschool way and solder flexible silicone wires directy on your FC.More wires and work involved but much more realiable than the little molex connector.

I'm almost finished building a quad witk MK electronics and will see if I can take a picture or two when finished.

We had I2C problems no one could solve.Even MK Germany didn't know what was going on.Until we soldered a direct connecting between the Fc and PDB.

Another copter had a molex of which one cable almost broke.Replaced it with a new one AND soldered direct connections.

When soldering direct connections on the FC you can leave the molex on.Doesn't hurt to have 2 connections.If one fails,the other one can act as a back up.

I hope things cleared up now.
 

J

J.T.

Spiralling out of control
I've had this happen. In my case I was descending and tried to yaw at the same time...and switched the motors off by mistake..DoH!
 

C

Choppercam

Member
I was changing the camera setting the other day when i picked up the mk and rocked it back and forth and all of a sudden everything went dead. The bind light was flashing madly and very faint (not like the flashing when you loose signal) I hadn't even been in the air so batt was full but when it happened the motors were not spinning as i was only testing the mount settings, any way i disconnected and plugged in again and it was fine. Done about 2 hours since and it has never crashed. Not sure what it was. No sd log as the motors weren't fired up.

Cheers

Tim
 



Meez

Meez

born to fly
Me too have several experiences dropped off during flying. It turn out my batteries was old and can't supply enough power already. Now i changed all my battery to new one. And i make sure to break-in all my new batteries. So far so good.
 

D

Dewster

Member
That's my worst fear of flying my little hexa. I actually had that happen to my AR-Drone. I think it was a battery issue. It was more of a brown out than a total power failure. The craft just dropped and then caught itself midflight.

I constantly check the solder connections to my power distribution board after having one wire come unattached (Whew). This happened before any flight tests though. Before and after flights I check connections. I also run batteries in parallel for high flying. My theory is hopefully if it is a battery issue that the other will provide enough power to land safely.

Things that make em crash: prop coming off, esc failure, bad power connections, batteries, flight controller....pilot error (most of my crashes....).
 

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