Vrs / Ivrs
Trying to summarize
Full VRS (see posts of Nick, Shawn)
- start with a vertical descent until you reach 75% vi (= 1040 ft/min for an averagely loaded R44)
- until fully developed VRS at 100% vi (= 1390 ft/min)
If lots of power available escaping is possible with power (example = tail rotor VRS's in sideways flying that can be controlled with lots of power)
But even Nick suggests putting nose down and flying out of it (see VRS thread post 232)
Some suggest to go to full autorot if altitude permits as alternative to shed of Vortex (..)
Quite some dangers here (see TC), not to be shown, should be test pilot territory (question: is this part of flight testing envelop similar to plank deep stall testing ? remains unanswered)
IVRS
- vertical ROD between 50% and 75% vi, so 700 - 1040 ft/min.
- or as Shawn, the Coyote and myself say, increase chance of IVRS by provoking tail rotor wake interference via slow backward flight at lesser ROD
Most people suggest to put nose down via cyclic only , some suggest also to lower collective (if lots of altitude is available) to get nose down faster, nobody suggests to use power
"I"VRS should be demonstrated using ample altitude safety margin, up to the instructor how big or small the "I" should be.
Risk factors
- the specifics of the helo aerodynamic configuration (horizontal stabilizer), making it more or less prone to take on a nose down attitude
- vi = weight requiring proportionate descent rates and altitude safety margins
m2c
d3