I was wondering if anyone has any insight into the following problem re: our 3d Robotics X8:
We initially were taking off with horizontal and altitude hold on, but the copter seemed to keep flying off in an unexpected direction and crashing. Eventually we took off fine without any holds on. Then while flying I put it in altitude hold, all good. But then as soon as I flipped the horizontal hold on, the copter took off sideways and down and crashed.
This may be related: eventually after flying a number of times fine, keeping horizontal hold off, the copter would beep all of sudden while flying, and then start going down to one side, and did not respond at all to throttle being all the way up. This was followed by sequential beeping of all motors (this video):
This sequence of the sudden beep (unrelated to any action we took) followed by the inexplicable sideways and down into the ground, then the motor beeping, happened a few times in a row so we stopped flying it.
Would be interested to hear any ideas on this, thanks!
That sounds like the ESCs beeping. I wonder if they are out of sync. Do they all spin up at the same time when you put on a little throttle?
I don't know if the ESC auto-sync protocol is different for an X8 than an Octo, but it is quite straightforward and can be done in about 5 minutes. http://copter.ardupilot.com/wiki/initial-setup/esc-motor/
Not sure if you have resolved this yet, but I came across another potential issue. Here in Panama we have noticed that the placement of the antennas of the Garmin dog tracker on the craft can have huge impacts on copter stability. I don't have any videos of this yet, but we have generally found that when the dog tracker is powered on the longer transmit antenna has an interference pattern at 5 second intervals that can cause severe pitch and roll 'lurches' on the copter, potentially leading to a crash situation at low speeds and altitudes. We have found two solutions - having the long antenna pointed down to the ground along one of the legs and have the smaller square patch GPS antenna of the tracker pointed below the horizontal plane of the copter, for example pointed straight out instead of up. But I suppose if the tracker isn't on, that might not be the issue.
Thanks for the dog tracker tip. We weren't using one.
Instead it seems the symptoms I was discussing were from the battery failsafe. One question - The batteries we got with our 3DR X8s are 6000mAh, but I see that in your tutorial it's entered into the MissionPlanner calibration at 11000mAh. Is that just because you're using different batteries? Or should we enter something different than then number on the outside of our battery (6000mAh)?
The value for the battery in Mission Planner should match that of the battery pack. This number is used by Mission Planner to estimate battery life during the flight.