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Phantom 2 motors cut out when descending
639 4 2016-8-29
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markusrowe
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United Kingdom
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I've had my P2 for almost a year now, with around 15 - 20 flights so far. I don't presume to be an expert, but I feel fairly confident in my flying ability and with the inner workings of the drone.
I activated Naza M a while ago merely intrigued by what settings were available. I didn't think I'd changed much but I had this problem with the motors turning off when holding the left stick down for a few seconds. I've since learnt that this was due to one of the settings I had changed in Naza M - Lesson learned.

I've since changed the settings back and had a couple of flights to test it out, all seemed ok.
Today I went out and flew in an open field, still wary of the potential issue but it seemed to descend perfectly. There was almost no wind today, it was a great day for flying.

Then, after going a little higher (around 60m) I started to bring it down and I had the same problem, the motors didn't seem to cut out completely, but I had no control over them. The P2 was falling for a fair few seconds while I was holding the left stick up, but it didn't react and inevitably hit the ground. Luckily it wasn't falling too fast and the grass in the field was really overgrown, so no damage was caused.

I've put a video up on youtube () can anyone shed any light on this?

I have also read on some forums that you shouldn't hold the left stick down 100% to descend, I struggle to believe this as I know some DJI controllers actually lock the left stick when you pull it all the way down. Am I wrong in thinking that?

Any advice would be appreciated.

Mark
2016-8-29
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dak162
First Officer
Flight distance : 2655604 ft
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United States
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That wasn't engines cutting out. That was severe turbulence due to your aircraft descending through its own down-wash. It is know as Vortex ring state (VRS). It is best to have horizontal motion when descending rapidly.
2016-8-29
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markusrowe
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United Kingdom
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That's great info Dak, thanks very much. I've been looking for some other explanation for this for a while now. I'll go out for a test flight again soon but keep moving forward while descending and let you know how I get on.
2016-8-29
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DJI-Thor
Administrator
Flight distance : 13602 ft
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markusrowe@gmai Posted at 2016-8-30 05:29
That's great info Dak, thanks very much. I've been looking for some other explanation for this for a ...

Hi, it does look like Vortex Ring State, you're lucky that the drone wasn't flying very high.  You see some users pull the stick all the way down is because P3 and P4 has solved this issue by using a different design on the shell and motor, and cap the maximum descending speed. So for P3 and P4 pilots they are safe.

Also avoid prop guards unless if you're flying indoors or congested area, there's anecdotal evidence that prop guards increase the likelihood of VRS.
2016-8-30
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roy
First Officer

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Wholding the left stick down does not cut out the motors. As a matter of fact my left stick has an auto lock down to bring the craft down without having to hold the stick down. Only after landing and stoping decent will the motors shut off. It's a built in feature. Also explained in the manual. Sit of is both stick down and in. Left stick down is decent only. If craft stops it's decent for a few seconds then it will auto shut off.
2016-9-23
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