ok so we bought the thing, we followed the instructions and double-triple checked, it still doesn't work.
the problem is: it is very unstable, it can't stabilize itself. We try to get off the ground , and within one second of take off, it goes insane, makes a sudden move/ flip... without touching anything but the throttle stick.
We tried to hold it in our hands while running, and it gave us a vague impression that it acts as it is in "+" config, although it is in "x". Also, it seems to try to stabilize in the wrong way: instead of compensating, it reacts exactly opposite, and increases errors.
one other issue: when throttle goes to 0, two motors stop fast, the other 2 take about 2 or 3 more seconds to... could that mean anything? Also, when it is almost taking off, but keeps contact barely, it spins... is that just vibrations, or does it mean anything?
I actually wanted to take a video of it but we ran out of propellers and also a motor mount broke. So a video will be coming shortly (if it helps any). We also have some logs, just say if it can help.
(we are begginers to quadcopters and RC in general, but say we know our way around mechanics and electronics and Arduino...we are students!)
thank you very much,
any help is welcome,