I have been flying a custom-framed aluminum Arducopter on the Ardupirates code. I took a break for a couple of months and then recently started up again. I decided to switch to the AC2 path, so I updated the firmware with the most recent version of the code using the Mission Planner. I then went through the setup and test procedure described in the wiki, setup the motors, setup the radio, turned on and tested the sonar, and so on. I setup my mode switch to start in "Simple" mode. Thus far in the setup and testing, everything seemed OK.
But when I attempt to take off, the quad is extremely unstable. As I increase the power on the throttle, even before it gets off the ground, I see it rocking rapidly, with small amplitude but high frequency. When I juice the power to take off, it goes up a few inches or feet depending on how much power I give it, but is extremely unstable, rapidly whipping and tilting back and forth in increasingly large motions, as if it's desperately trying to get control but loosing it, and then flips and crashes. This same behavior happened consistently three times before I decided I had a definite problem and I needed to diagnose it.
I've seen various bad flight conditions (backward props, lose motor connections, broken props, etc.), but I've never seen this rapid oscillation and wild instability before.
Does anyone have any suggestions?
Replies
1) Is your APM facing forward? (between the arms for X or towards the front arm for +)
2) Have you configured correctly for X or +?
3) Have you run the "motors" test in the CLI to make sure you've got all the motors hooked up right and props spinning the right directions? It's the same as before, but always worth testing again.
4) Have you held the quad in your hand with motors are 1/4 throttle and tested whether stick movements tilt it in the right way?