This just started on my IRIS. A few seconds after takeoff the IRIS just seems to loose power and settles back to earth even with full throttle. I have tried it with a second fully charged battery, same result. I doubt it is related, but immediately prior to this I had relocated the FrSKY antenna wires as described in the troubleshooting guide. I saw a significant improvement in GPS performance, but now it won’t stay in the air.
try recalibrating radio.
I forgot to mention recalibrating the radio was the first thing I tried. No joy.
I’m going to point a friend of mine to this thread - he has the same exact issue as you. Maybe you guys can figure it out. He’s gone around and around with 3DR to no resolution. some days it will fly fine, but most of the time after and arbitrary amount of time it will descend to earth without warning. it seems to be more frequent with the gopro on it, but a little gimbal and cam should be nothing for a quad of this size and price. The last time he had it out it pulled this stunt from about 5 feet up smashing his cam and busting 2 arms. he’s fed up. Good luck.
Mark, I had a look at your log. The problem seems to be that your battery is dead. It starts off with voltage of only about 12.0V, and is down to 11.0V in less than half a minute. Towards the end, it’s down to 10.5V, and the Iris is trying as hard as it can, outputting full throttle.
I’d try a new battery.