Unable to maintain lift - Need assistance

I have a Walkera Scout X4, recently I got tired of fighting Walkera’s watered down version of arducopter so I ended up pulling out the flight controller and loading the stock arducopter 3.2.1 build on it. They are using some sort of APM2 board. May be custom built, but I doubt it.

So, I got 3.2.1 loaded, and everything looked good. Took it out for a test flight and seemed to be in good shape. Very stable, good response, everything seemed to be good. Put in in the case and left it till the weekend. Pulled it back out, popped a fresh battery in and went flying. 6 inches off the ground, and flip over… OVER AND OVER again, chased that issue for 3 days before I noticed that all the PID controller values in MP were 0… Odd, last thing I did when flying was an autotune, landed and took it back up just to make sure it still looked good. So, once I saw that, I loaded the stock param file for the X4 back on it and took it up, back to flying good. It was 3:00 in the morning when I saw that and got it fixed so just took it up long enough to see it was flying. In the case it goes… Next day, head to the park, pop in the other freshly charge battery and take off. So far so good… Then after just a few minutes, I was barely able to keep it in the air. It was stable, but not maintaining lift. Full throttle was keeping the landing gear brushing the top of the grass. Any change of roll, pitch or yaw makes it drop like a stone.

So, I start chasing that problem… And now I am at a loss. At first I was thinking it was a bad battery. I have tried it with a brand new, freshly charged pack and it is still doing it.

RC Input looks good from the RX, it’s seeing the full PWM value for full throttle. Ran the ESC calibration (or as much as you can on whatever ESC’s walkera is using…) nothing seems to help. I reloaded the firmware fresh after erasing the chip with AVRdude and started fresh. Once again, had a few minutes of good flight, then it started to sink, and any maneuvering made it worse.

I also ran a short GPS track around the field, the autopilot was not able to keep it in the air either. I wish I had a camera handy so I could have gotten video… I had the WP ALT set to 20FT (in case it went nuts, it either wouldnt have too far to fall, or be easier to get out of a tree) while it was flying the altitude of the scout was all over the place, even bounced off the ground a few times and kept trying to fly.

I went in and turned on full logging and did it a few more times… One thing that strikes me as really strange is the data in the logs… One of the logs shows good IMU data, another shows nothing but 0… The data in the logs seems very spotty to me, could just be me though as I am not that familiar with the logs yet.

The logs are on my dropbox folder…
Can anyone offer any suggestions? Or maybe take a look at the log’s and see if they are of any value?


I should also mention one other thing… I don’t think it’s related, but who am I to know :slight_smile:

About half the time when powering the quad on, one or two of the motors will spin up. Most of the time for half a second or so, mostly it’s the front two motors, have seen it on one of the back ones though. And just once, I have seen it not just pulse, but stay on…

Hello. Having here the exact same problem, but wit a QR X800. Also replaced FCS 800. Did you find any solution? Any info will greatly be appreciated. Ben

try throttle calibration on your esc and radio calibration from mission planner