Helicopter Lessons: Vortex Ring State / Settling with Power (Part 2)

Introduction

• Part Two of the Vortex Ring State / Settling with Power series.
• Focus on understanding the three requirements for settling with power, conditions conducive to it, and recovery methods.

Requirements for Vortex Ring State

1. Airspeeds less than ETL
   • ETL (Effective Translational Lift) is when an aircraft is operating in clean air, having outrun its vortices.
   • Below ETL, wingtip vortices affect the rotor system.
2. Rate of Descent Greater than 300 feet per minute
   • This condition promotes upward air flow that can form vortices.
3. 20% to 100% of Available Power Applied
   • Sufficient power is applied but not enough to stop the descent.
   • Different from autorotation which only has upward air flow through the rotor.

Conditions Conducive to Vortex Ring State

1. Steep Approaches
   • Approaching at angles of approximately 30 degrees (higher than normal and auto-rotative angles).
2. Downwind or Tailwind Approaches
   • Reduced airspeed and altitude, within range for vortex ring state.
3. Poor Altitude Control in OGE Hover
   • No airspeed, power applied, and unchecked descent rate can lead to vortex ring state.
4. Hovering Above Max Hover Ceiling
   • Insufficient power and excessive vortices due to increased power usage.
5. Descent from OGE Hover
   • Less than ETL, power applied, risk of exceeding 300 feet per minute descent.
6. Formation Approaches
   • Operating in disturbed air from another helicopter's wingtip vortices.

Recovery from Vortex Ring State

1. Initial Collective Increase
   • Early stages: may break the cycle before full vortex ring state develops.
   • If descent rate increases, collective increase is no longer an option.
2. Establishing Directional Flight
   • Any directional movement to break ETL.
   • Forward right cyclic with right pedal reduces power required, allowing increased collective.
3. Autorotation (Altitude Permitting)
   • Bottom out the collective, establish directional flight, then increase collective to exit vortex state.
   • Experts suggest right forward cyclic with right pedal for effective exit.

Conclusion

• Vortex Ring State: Rotor system engulfed by vortices.
• Settling with Power: Helicopter descends into its own downwash.
• Recap of techniques and conditions discussed to avoid and recover from vortex ring state.

Reminder: Ensure safe flight practices and keep learning.

End of Lecture.