So I first want to say that unfortunately my micro sd card was not installed so I don't have a gpx file to help figure out this mystery. I was flying a project shooting stills and was in Altitude hold. I was wearing the earbuds and my MX20 told me receiver error. I was about 150 feet up, but I could see my led for my front boom started to flash. Most likely corresponding with the receiver error message. I started to bring the copter back and I took it off atl hold to start to descend. Immediately all 6 motors came to a complete stop and the copter began to fall. I quickly put it back into alt hold thinking it might recover, the motors did actually come back on and were trying to spin, however the rate of descent was too great and the copter landed in a tree (luckily). The copter should have returned home with the fail safe if it lost signal. I have talked to the guys at Quadrocopter and they are stumped as to what it could be. Thought I would reach out to everyone here to see if anyone has any ideas. Overview of copter. All cables are attached. Molex cable attached No visible burn marks from potential short. Running QC 10,000 Mah 4s lipo and had plenty of juice left. Any help would be greatly appreciated
Could be any number of things then. Did you have the Flashing of the LED's on the booms set for low voltage or any other warning?
I do, but the battery was at 15.9v when it crashed. The copter will also tell me when I have reached the "battery low", but it was telling me "receiver error"
Receiver error is an indication of a number of potential things. Setting up failsafe properly on MK systems is tricky. Sometimes the radio has a failsafe that can contradict what the flight controller does, which is terribly confusing. My first guess would be some kind of spurious radio problem caused by either a loose connection to the receiver, low battery level or other failure in the transmitter, or even possibly the radio getting interfered with somehow. Is there a chance you had the SD card in your transmitter and logs recorded on it? There's information in that log that can be very valuable in diagnosing radio-specific problems. But the RTF systems generally don't have that set up, and it takes a few minutes to enable. Gary Haynes wrote a succinct guide to how to enable Graupner logging here: http://forum.freeflysystems.com/ind...he-graupner-radios-to-record-flight-logs.843/
Steve, Thanks for the suggestions. I just plugged the sd card from the tx into my computer and a data log was not established so no luck there. At the time of the crash the transmitter was at about 5.2v so that shouldn't have been an issue. Here's something that I forgot to mention. The project I was flying was right on the Mexico/US border. I was in the US, but shooting business parks right there. Not sure if there was some crazy interference from my location. Unfortunately I won't know because the SD card wasn't in. (I won't make that mistake again). You referenced loose connections to the receiver. Is there a connection you can think of that would cause a loss of power if not connected correctly?
Garrett, Know if there were any nearby cell towers? I have seen a Cell tower do something similar (they were able to recover the UAV and land it), and I know there are quite a few on the border.
There are two servo connectors going to the Graupner receiver (maybe more). The two that come from the MK Flight Controller are the telemetry one in the top (signal only) and the main output (signal, power, ground). If that full servo cable comes loose, or if the power lapses, it can cause the receiver to fail. And this can happen if one of the RECOM on the MK board is faulty. That's the bit that steps down the voltage to the 5V DC that the receiver wants. If you have other things plugged into the receiver, one of those could cause a failure, too. Do you have any other devices plugged into the Graupner receiver? Certainly there could be some heavy duty radio stuff going on at the Mexico/US border, including the distinct possibility of some deliberate security things that could be the cause of your problems. But who knows...certainly not me.
"I was flying a project shooting stills and was in Altitude hold. I was wearing the earbuds and my MX20 told me receiver error. I was about 150 feet up, but I could see my led for my front boom started to flash. Most likely corresponding with the receiver error message. I started to bring the copter back and I took it off atl hold to start to descend. Immediately all 6 motors came to a complete stop and the copter began to fall. I quickly put it back into alt hold thinking it might recover, the motors did actually come back on and were trying to spin, however the rate of descent was too great and the copter landed in a tree (luckily)." Hello, Since you were able to fly back and deactivate/activate alt hold I don't think come home was triggered. The error - receiver strength is great since it warns you when it gets low therefore prompting you to get closer, change Tx antenna position, and/or say a quick prayer. Holger did have a safety motor turn off if you were in come home and had a MotorNOK error which usually translated to being stuck in a tree or in the ground binding a motor. Unfortunately without the Gpx file it's just speculation. Best, Jeff
Is it possible that you can connect up the Flight Control board with MK Tool on the PC and read out the state of the parameters, then save that as a .mkp file (it's just a text file) and then post it that. Also, if you get to do that, post a screen shot of the MISC tab. My working hypothesis is that you did not EDIT: may have the same issue as Tim Sessler had. See http://forum.freeflysystems.com/ind...tar-mikrokopter-and-graupner-mx20-combo.5397/ -- those are my images in his posting based on my analysis of his GPX file and -- more importantly, the current settings in the Flight Controller. So the pivotal question is whether you have "Use vario control for failsafe altitude" checked or not? If you did not, then what value did you have set for Emergency Gas? If it was very low, on loss of transmitter signal, if the copter went into emergency landing mode, the motors would stop. EDIT: Sorry about that clunker (aka brain fart), in the paragraph above....see the EDIT above! Andy.
And there is the whole other problem of MK NOT going into failsafe which I found totally by accident (checking Tx off FS) this past Spring> 5/19/2014: From Lothar Freudenberg at MK tech support: "Graupner did change the FailSafe function in the receivers. If you use the latest Software on your receiver you have to go into the Menu" ""Setting & Data view". There go to the window "RX Fail Safe Vx.xx" and change the "MODE" of channel 1 to "OFF". Now the copter will again receive the lost signal."
I would guess as well that you forgot to tick 'use various control for failsafe' so it used 90 stick settings instead of 90% of hover gas ( or what ever value you used.) Just as guess though..
As an update I will say I have yet to have any additional issues with the copter and I am beginning to think more and more that it had something to do with the close proximity to the US/Mex border. I will just decline projects that close.
It could have been a bad battery did you test that battery afterwords. I had a battery failure at 150 feet with the above 10Ah 4s Qc battery. I got super lucky that some how no damage occurred to copter. I was flying in a field with tall wild grass that cushioned the impact. I took flew out about few hundred feet low altitude than started a reasonable climb to 150 feet. I started to get a battery alarm, as I was bringing it back the copter lights flashed and it started to descend rapidly. I went to full power in manual and it still kept falling until ground impact. The copter had enough power to keep the attitude level which helped keep it from smashing into pieces. When I looked at the data card GPX file when I went full throttle the battery voltage sagged to 12.8 V. When the battery was no longer under load it was reading 15.6 V resting voltage. I used my field tester and found that the battery had severely discharged one cell. Internally something went wrong with that 4S battery. What you describe almost sounds like the battery failed in flight. Way to test it is to take a battery tester and view each individual cell and see if one is extremely lower than the other.