Well maybe it is the Rotor Wash effect, but I am starting to think otherwise.
The thing is I flew it perfectly the day before all over the place, full speed, I tried the return to home feature, no problem.
Then the next day, I flew it fine, doing figure eights and square patterns at all kinds of altitudes, I took it up as high as I could. Brought it down, no problem.
I would corner rapidly when flying square patterns, it would wobble a little on the hard corners, but Quickly recover.
then I descended like I was before and all of a sudden it went into the Wobble, at 20' and came down kind of fast into the grass.
Then I flew it again, and the 1st batt. warning light sequence started,(I still had 1-1/2 green bars on batt. indicator)
So I brought it in, it was not very high,-30' or so, and it went into the Wobble, as I got to about 15' off the ground.
,,,,I tested it again, and it did it again.
So now I am afraid to fly it until I do a full reset and re-calibration of the firmware.
Sure Rotor Wash is a concern, but the way I was consistently getting wobble when the day before I had none makes me suspicious.
And I was doing straight down vertical descents the day before, without these problems.