Phantom 2 suddenly drops from the sky

[randlarson]

Maybe it's coincidence, but ever since I recently updated my Phantom 2 it has crashed more than ever. Each time it crashes when I'm descending a bit too fast. I've found that I must descend very slowly, there is little or no strength to suddenly push up if I find it's descending too fast.

A friend was using my Phantom yesterday and he crashed two times. The first time, the copter did a little wobble, then he says it felt like there was no power. It crashed into a palm tree. Time to get a ladder. You can see the video here:

https://www.dropbox.com/s/lvxc3bcmwh15gw0/crash_1.mp4

The second time it crashed, it was as if the craft was hit from the side:

https://www.dropbox.com/s/zixddkdk6u8xt69/crash_2.mp4

Each time the crash happened during a descent. In these two videos the descent seems to be fairly moderate.

Does anyone have any suggestions?

 

[Hawkeye 1]

VRS.....vortex ring state. Do a little research and you'll see that your crashes almost assuredly are caused by this condition.

 

[randlarson]

Someone mentioned that in a previous post. I'm learning about that. But, if you watch the video it's as if the craft suddenly quit and dropped. Today when I did some tests, I was extremely careful during descent and noticed that at times it felt like the craft was literally being sucked down. So I was extra careful. In the two videos, the craft is quite a ways in the air. Would the vortex ring state relate to this as well?

 

[Hawkeye 1]

Yes, I think it would. As a side note, does your Quad have prop guards installed? There has been quite a bit of evidence presented on this forum that they make the Quad much more susceptible to VRS.....sometimes when just hovering, much less descending. One way to help avoid this condition is to combine your descent with some other movement.......either forward, backward or lateral.

 

[randlarson]

Yes, I do have prop guards on. And now that you mention it, I tried hovering for a long period at about five feet. It felt like it was being pulled down.

 

[RScottCampbell]

Hi all, I'm the pilot in question on this one.

I hadn't known about VRS before, however, after reading up on it last night i'm pretty sure I've experienced this a few times. It was good learn what can be done to get out of that state.

The below are descriptions from my perspective of what happened. Do they sound like VRS?

Neither crash fits exactly into the craft state or control response of VRS as it's described.
- 1st crash - the craft was not descending, rather moving sideways when it started to severely wobble and then as it was moving sideways did a relatively soft, uncontrolled, no stick response at all, descent into the palm tree. When you watch the video, I lost stick response as it starts to wobble. The craft kept moving sideways and then down.

- 2nd crash - this one I was doing hard descent with no other movement (I won't be doing that again now that I know about VRS) and then at about 40 feet altitude (a guess) it was as if the craft got hit by something and it actually just fell. I had a spotter and she said there wasn't any wobble, just a sudden tip to one side then straight down. I didn't even have time to respond the the gut reaction of increasing throttle, let alone change direction or anything like that. However, when looking at the video it's clear the motors/props were still providing some lift because it didn't fall fast enough to be completely free fall.

Do these descriptions sound like VRS?

Thank you.