Development of VRS

[rubidug]

I am reading/studying the Wagtendonk book for the second time, hoping to start my PPL training next month.

 

Not to start another VRS vs SWP arguement, but the title of this part of the chapter is: Vortex Ring State (Settling with Power) LOL

 

On page 159 it shows the requirements for development of VRS as:

--low or zero airspeed (below TransLift)

--some power

--rate of decent 400-800 ft/min.

 

Does that mean that ALL, or SOME of these factors are needed to start VRS? To me, its not clear.

 

In other words, assuming no wind, can VRS begin from a hover at zero airspeed? If so, how are heli's able to do long line, ENG hovering at high altitude, etc.

[pilot#476398]

Yes, they are all needed to get into settling with power (together)! An airspeed less than ETL can be zero airspeed, in fact settling with power is usually initiated during training from a hover at around 2000 feet or so. Just lower the collective and start a vertical desent. When it get to around 400 fpm raise the collective and you'll find yourself in it!

 

Helicopters can do those other jobs by simply not letting a desent rate build up while in a hover!

[rubidug]

So, it is ALL 3.

Thanks for clarifying!