Vortex Ring State

Hi everyone
i have some questions about vortex ring state that i couldn’t find answers by googling.
i know that VRS happen when we descending fast or air pressure under props goes near zero and we could survive from this state by cutting up forwarding air flow with propellers.

but some questions
does is it happen less to Hexa and Octocopters ? (because of more motors and power)
does is happen less with a Octox ? or this motor arrangement could make stronger VRS ?
could VRS flip a multi rotor ?
is motor KV could affect ?

@mboland
@Leonardthall
@xfacta
@Eosbandi
@dkemxr
@andyp1per

Does it happen at all on multirotors?

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Hi @dkemxr
yes it seems that its happen to multirotors



but i cant find any video with hexa or octocopters

Video 1: unstable flight control
Video 2: Looks like low battery
Video 3: unstable flight control

Or anything other than DJI phantoms.

VRS is a very specific aerodynamic condition that multirotor propellers fundermentaly does not support. Combine that with the 4 or more independent propellers destroying anything that resembles VRS that does form. Extremely unlikely to happen on a normal multi.

Descending into your own downwash, stalling your propellers, and a number of other effects that could be mistaken for VRS, sure.

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yes it seems that its limited to DJI phantom 2.

i was created this topic because last week one of my quads started wobbling while fast descending without any lose of control , i was stopped it just by moving throttle stick to center

so it seems that it just descended to unstable air that generated by itself, is it right ?
note : copter was tuned and have may successful flight

I think the term is often misused…

Depending on the tune of the copter descending into your own prop wash is not as critical event as a traditional helicopter.
If your copter has lots of power and is sensitively tuned you might be able to flip it, but I have never observed that.

The biggest issue is power to get out of it.
If your descending fast and apply power it can take a lot longer than you expect to arrest its descent.
I have pancaked a few times doing this playing with a 450 size indestructible frame I make for the cattle musterers.

Golden rule, if you want to descend fast have some lateral motion as well.

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