Posted by Miles Smith on November 20, 2012 at 9:02pm
Hey all,I've been flying my 3DR hexacopter for a few weeks now, and have been having a ton of fun and learning a bunch!Last week, I tried to attach a 5.8Ghz Transmitter to my hexa, and the setup I had been using deployed the camera by zip tying it down to one of the arms. Now I knew this would obviously set it's center of gravity off a bit, but I figured that the APM software would work that out by applying more lift to that side.Without the transmitter, this worked. However, when I added the transmitter, and also a 2650mAh 3s lipo to power the whole camera setup, I think it put it way off balance.The hexacopter went up in the air just fine, but after approx. 60 to 90 seconds, it started spinning on it's left-to-right axis (the side with the camera fell first).Now what is really weird is that the craft was stable as could be to start, but then it appears that it hit some sort of software correction limit. I don't know much about PID values, but I would guess that a value that's designed to correct pitch was so overloaded that it rolled over to a negative value, causing the flipping.Now to my question, how much is too much? I've now upgraded to a gopro, so I figure that the smaller weight will make it easier, but does it have to be EXACTLY centered? If so, I don't have much clearance under my 3DR Hexa-B frame, does anyone have any recommendations for either a new frame, or new landing gear that will increase the ground clearance?
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The camera doesn't have to be centered, but the weight does have to be balanced. So if you put the GoPro on one side you could offset the weight by putting a battery on the opposite. Getting the balance as close to perfect as possible is very important. ArduCopter can "learn" to fly out of balance but this is not a good solution because some drivetrains would always work harder than others and it would reduce the limits the copter would otherwise be capable of with evenly distributed weight (maximum payload, fast vertical ascent, rate of yaw, etc.).
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The camera doesn't have to be centered, but the weight does have to be balanced. So if you put the GoPro on one side you could offset the weight by putting a battery on the opposite. Getting the balance as close to perfect as possible is very important. ArduCopter can "learn" to fly out of balance but this is not a good solution because some drivetrains would always work harder than others and it would reduce the limits the copter would otherwise be capable of with evenly distributed weight (maximum payload, fast vertical ascent, rate of yaw, etc.).