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Vortex ring
is a condition which can have disasterous effects.
Vortices are always present around the trailing edges of the rotor. In the following conditions they will intensify to
such an extent as to cause the blade to stall which results in a sudden loss of thrust and a rapid loss of height.
Vortex ring can only occur when all three of the following conditions occur:
1) The blades are being driven - Power On (i.e. not auto-rotating).
2) A high rate of descent (greater than 300 ft/min in the R22).
3) Low forward speed (less then 30 kts).
Removal of any one of these avoids vortex ring.
In a vortex ring condition, raising the collective makes matters worse and instead of reducing the rate of descent it
actually causes it to increase.
To recover from vortex ring you need to alter the airflow conditions causing it. The conventional recovery is to apply
forward cyclic and thus increase the airspeed then wait until the airspeed increases beyond 30 kts before applying
more power.
Obviously if vortex ring is allowed to occur too near the ground, recovery by increasing airpseed will not be possible -
the following photo shows the end result!
Vortices are always present around the trailing edges of the rotor. In the following conditions they will intensify to
such an extent as to cause the blade to stall which results in a sudden loss of thrust and a rapid loss of height.
Vortex ring can only occur when all three of the following conditions occur:
1) The blades are being driven - Power On (i.e. not auto-rotating).
2) A high rate of descent (greater than 300 ft/min in the R22).
3) Low forward speed (less then 30 kts).
Removal of any one of these avoids vortex ring.
In a vortex ring condition, raising the collective makes matters worse and instead of reducing the rate of descent it
actually causes it to increase.
To recover from vortex ring you need to alter the airflow conditions causing it. The conventional recovery is to apply
forward cyclic and thus increase the airspeed then wait until the airspeed increases beyond 30 kts before applying
more power.
Obviously if vortex ring is allowed to occur too near the ground, recovery by increasing airpseed will not be possible -
the following photo shows the end result!
British Airways: "BA123 request for push back clearance from terminal."
Control Tower: "And where is the world's most experienced airline going today without filing a flight plan?"