Helicopter shaking on descend

[sLYFa]

I noticed the Mi-8 to increasingly shake when flying at high forward and/or vertical speed, which I believe is realistic (Vortex Ring, blade-stall). However, I also sometimes expierence shaking when descending at low forward and vertical speed.

I was doing a FARP approach with 50km/h forward and 3m/s vertical speed.

At about 50m altitude the helicopter started moderately shaking albeit with no noticeable influence on controllability. Anyway, I wonder if this is intended behavior and how it can be explained, as I believe there should be no blade stall occuring at these low speeds.

[lmp]

I noticed the Mi-8 to increasingly shake when flying at high forward and/or vertical speed, which I believe is realistic (Vortex Ring, blade-stall).

 

Vortex Ring State does not happen at high forward speeds. It happens in or near hover when the helicopter is descenting quickly.

 

I was doing a FARP approach with 50km/h forward and 3m/s vertical speed.

At about 50m altitude the helicopter started moderately shaking albeit with no noticeable influence on controllability. Anyway, I wonder if this is intended behavior and how it can be explained, as I believe there should be no blade stall occuring at these low speeds.

 

You were transitioning from ETL to hover and if you would continue to slow down without decreasing that descent rate, you would end up on the verge of VRS. Both of those situations (ETL to hover transition and VRS) cause shaking.

[MauganRa84]

I enjoy the shaking on descent, makes it feel like a theme park ride hahaha.

[TimeKilla]

Vortex Ring State does not happen at high forward speeds. It happens in or near hover when the helicopter is descenting quickly.

 

Yep only below 40 knots could become an issue.