Vortex Ring State
A must know for all members here.

Very useful. Thanks for sharing.

Very nice share indeed! I wonder if some of the "It fell out the sky" is actually that Vortex Ring State making the Inspire 1 appear defective I'm certainly going to be watching out for it.

Great Tutorial big guy. It would be nice if we had a section on the forum to post Tutorials. If it happens I would like to see it monitored by a moderator to insure that the posts are beneficial in nature such as this Post.

rodger Posted at 2015-3-18 22:08
Great Tutorial big guy. It would be nice if we had a section on the forum to post Tutorials. If it h ...

Captain Obvious Posted at 2015-3-18 21:49
Very nice share indeed! I wonder if some of the "It fell out the sky" is actually that Vortex Ring S ...

My phantom did just that, and i was over the water.
Altitude was only 5-7meter and got caught in a fortex
There is some video of this on my youTube channel.

I was thinking of this just this evening reading about people concerned that doing a rapid descent could turn off the power by holding the stick to the bottom for more than three seconds. My concern was vortex ring state. Since I have started flying my Inspire 1 I always make a point of translating during faster descents.

What is translating?

A known culprit to the phantom vortex ring state are its prop guards.. Without them far less people are experiencing it.. But even so it's quite easy to get out it if you have enough altitude. The inspire has much greater vertical speed compared to the phantom so it could be that vrs is more likely, but does it also happen while hovering? I almost maintain some sort of forward movement when landing, to prevent vrs, but when shooting I hover a lot.
Btw, that's one bad ass crashproof quad he's flying! Great post!

The is purportedly what brought down the stealth helo in the Bin Laden raid. Plenty of docs on it and a few really creepy videos of it actually happening to full scale helicopters can be found online. Never really occurred to me that it might happen to a quad but certainly plausible. Good post.

I have had this with the I1. Descending from around 100m with very little wind the bird developed a bad wobble, with the slightest of forward input on the right stick, she came out of it and continued  the descent smoothly. I never knew that wobble could have ended in disaster.
I will be looking out for this in future, thanks Dundee.

what a great video.  Some invaluable information here.  Thank you for sharing
Cheers.

Jason

VRS is NOT a guarantee you'll crash!!! If you enter VRS "go full throttle and forward. or yaw r or l and forward. you pop right out of it. I have practiced this with a smaller, less expensive quad, by entering VRS on purpose and flying out of it in this manner. I believe you just have to disrupt the Vortex below your craft. I haven't tried it with the Inspire 1 yet but this maneuver has worked every time with the cheaper craft I used.

This may also be why both the Inspire and Phantom have maximum descent speeds. The Inspire's is 4 m/s and the Phantom's is 2 m/s.

DJK Posted at 2015-3-19 08:47
What is translating?

Moving in the horizontal plane. Thus if I descend quickly I feed in a tad of right joystick to keep the quad from dwelling in its own turbulence.

I saw this video some time ago and because of it I always make sure that I am moving with some horizontal velocity when making descent.

These videos are so helpful to learn from other's mistakes and experience so we don't have to experience it ourselves. I really appreciate those who take the time to document these things for us.

So glad I saw this as I often film fast drop descents, though usually spinning.   Haven't even noticed this but will now be more careful.   

I'm guessing here but if you had enough altitude, pull right back on the thrust, drop through the turbulence and "Presto" you're good to go!
Yes? No?
I think I'm gonna wait for one of you guys to test my theory. Let me know how it goes.

markaguille Posted at 2015-3-20 18:29
I'm guessing here but if you had enough altitude, pull right back on the thrust, drop through the tu ...

Thanks Dundee, this is really helpful. I will never descend the same again.

VRS can be a very bad thing if you are flying fast close to the ground and stop suddenly. It will lose altitude fast as it falls into the disturbed air. I almost belly flopped onto the camera two days ago doing a high speed run up the road. I was about 4 feet off the road and I stopped quickly and just caught it from smack down with full up on the stick.

Dangair Posted at 2015-5-23 15:22
VRS can be a very bad thing if you are flying fast close to the ground and stop suddenly. It will lo ...

That is interesting but I am surprised that VRS is the culprit. I find that the altitude hold is pretty weak when translating from forward flight to hover. I have seen mine drop a couple of metres and VRS certainly was not the cause. I have even seen it slowly land itself from a hover over some thirty seconds from 2m height. It seem like the aircraft flies into some high pressure caused by the rotor wash and the controller instructs it to descend. Mind you, it is still vastly more accurate than the autopilot on any real aircraft that I have flown.

Dangair Posted at 2015-5-23 15:22
VRS can be a very bad thing if you are flying fast close to the ground and stop suddenly. It will lo ...

That is interesting but I am surprised that VRS is the culprit. I find that the altitude hold is pretty weak when translating from forward flight to hover. I have seen mine drop a couple of metres and VRS certainly was not the cause. I have even seen it slowly land itself from a hover over some thirty seconds from 2m height. It seem like the aircraft flies into some high pressure caused by the rotor wash and the controller instructs it to descend. Mind you, it is still vastly more accurate than the autopilot on any real aircraft that I have flown.

Dundee,

Thanks for posting this.  Really good explanation of why not to descend too fast and explained in a good simple way.  
Pretty durable little machine he uses in the video also.

Cheers.

fullyestablishe Posted at 2015-5-23 17:05
That is interesting but I am surprised that VRS is the culprit. I find that the altitude hold is p ...

well it is. imagine standing  under the aircraft, pretty windy right? when the aircraft is flying and stops suddenly it must make a compensation maneuver and return to its neutral position. In essence it is spraying chopped up wind all over the place and you are stopping right inside of all this displaced turbulent air. Whats worse is it is being reflected in many directions off the ground adding to the turbulence. The propellers are wings and wings do no perform well in turbulence the like to cut clean air. If the same situation happened to a prop underwater it would cause cavitation.

After viewing this I do believe that I have had this happen.     Not to the point of crashing though.       I notice on straight down descent the pitch of the motors seems disrupted.    I look up and see the bird wobble as in the video.     As soon as it began it stopped.     Happens more than I would like to admit.   Been chalking it up to bird fighting wind on descent.       Highly aware of it now.       I find myself descending on a slope.    Takes all of the formentioned wobble away.    Thanx Dundee.  

Dangair Posted at 2015-5-25 01:57
well it is. imagine standing  under the aircraft, pretty windy right? when the aircraft is flying  ...

Dear Dangair,
I certainly understand what you are saying, I was merely making the distinction between a fully established descent into VRS as opposed to flight into disturbed air that is transient. Both of us know when flying proper aircraft how unpleasant flying in one's own prop wash is, or wake turbulence. One can often hear the Inspire dealing with disturbed air but I would not classify it as VRS, VRS is when you have very little control left, like a super stall in a high tail aircraft. I do not disagree with you and it was only a point of syntax. My experience is that DJI have done a good job of keeping us all within the fight envelope.

A USEFUL REMINDER TO ALL

Aloha dundee,

     This is the video I was able to use to get Vortex Ring State into Wikipedia on the Quadcopter page and quadcopters into the VRS page.  The editors cut a couple other videos but this one was very clear.  There was a lot of resistance to recognizing that VRS applies to quadcopters.  First time I ever fought it out in the back "discussion" pages.

     BTW, VRS is also known a "descent under power".  No matter how much you try to climb out of it, it will not work.  Only translating can get you out of trouble as noted in the video and some of the comments here.  

     The new DJI products have introduced tilt to the motors to reduce VRS.  The P2s, up until the P2 v.3 had VRS problems.  The firmware reduced the P2 descent speed to 2 m/s for that reason.  The new P3 (and the P2 v.3) now have a descent speed of 3 m/s with the tilted motors.

     Besides the Stealth H-60 in the BinLaden raid, the Osprey V-22 that crashed during certification testing had one of the rotors go into VRS.  VRS is definitely something to be concerned about.  But, I never did find propguards to have any effect one way or the other as some noted.

Aloha and Drone On!