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This is Part 2 of 2 covering Vortex Ring State / Settling with Power. If you missed the first video I'd recommend checking that one out first before watching this one. Here is the link (   • Vortex Ring State / Settling with Pow...  ). In the first video we defined these 2 terms as well as went into what exactly is occurring in the rotor system. In this video I address the 3 requirements for a Vortex Ring State, conditions conducive to encountering it, and how to recover once you get into it. I hope you enjoy!

3 Requirements for a Vortex Ring State:
1. Airspeed greater than Effective Translational Lift (ETL). This is important because ETL directly refers to the outrunning vortices and operating in clean, undisturbed air. If you're faster than the vortices, Vortex Ring State can't affect you. Here's the video on ETL if you want a refresher (   • Effective Translational Lift (ETL) in...  ).
2. Rate of Descent greater than 300 Feet per Minute (FPM). This magnitude (and greater) of vertical descent can mean significant upwards flow of air through the rotor system.
3. 20%-100% Power Applied. This means that you are in some sort of powered flight and not in an autorotational state. In an autorotation, there is only upwards flow of air through the rotor and vortices cannot form.

Conditions Conducive to Vortex Ring State:
1. Steep Approaches. These approaches tend to have high rates of descent relative to forward airspeed.
2. Downwind/Tailwind Approaches. Your rotor will descend below ETL sooner in these approaches.
3. Poor Altitude control when hovering Out of Ground Effect (OGE). Without a good cross check, a rate of descent could form easily. Due to OGE hovers typically being high power Requirements with relatively low/no airspeed, the only thing left for a Vortex Ring State is a descent in altitude.
4. Hovering above Max Hover Ceiling. Hovering this high requires all available power which generates massive vortices around the rotor disk. Much like #3, all it takes now is some altitude loss.
5. Descent from OGE Hover. This is where it's critical to keep rate of altitude loss in check and not allow more than 300 FPM rate of descent.
6. Formation Approaches. While in formation you are subjected to the vortices of the aircraft in front of you. Encountering these vortices when slower than ETL could cause massive rate of descent shifts which could then easily lead into a Vortex Ring State.

Recovery
1. Initial Collective Increase. In the early stages of Settling with Power a collective increase could stop the development of Vortices. However, if the Vortex Ring State has already occurred, this could exacerbate it and cause even more altitude loss. If this is the case, proceed with options 2 or 3.
2. Directional Flight. By accelerating in flight (in any direction) through ETL the rotor outruns the vortices and operates in cleaner air. most experts say the most expeditious way to recover from Vortex Ring State is with right Cyclic and right pedal.
3. Autorotate. This last option is altitude dependent but escapes the vortices by falling away from them. By entering an autorotational state, the airflow becomes 100% upwards through the rotor system and the rotor escapes the vortices. However, directional flight must be established somewhat before collective application or the ring State could reform.

That concludes this 2 part video. I hope this helped clarify the topics. If not, feel free to ask questions in the comments section below. If you liked the video, make sure to click "like" below and subscribe to get notifications of future videos.

As always, safe flying.


If you're just getting started and want more information, pictures, and more explanations, I'd recommend reading the Rotorcraft Flying Handbook - http://amzn.to/2ifPlnZ

If you've already got a basic understanding, and want to further your professional helicopter education with advanced helicopter concepts, I'd recommend reading Cyclic and Collective, by Shawn Coyle - http://amzn.to/2ifQGLx