Autorotation NR trend
Thread Starter
Joined: Apr 2006
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From: Europe, Middle East, Far East and rarely USA ... so far !
Autorotation NR trend
May be this is a silly question but it arose among many "professional" pilots without any confirmed explanation.
The question is:
during an autorotation at constant speed and considering a helicopter with a rotor turning CCW like the Agustas, if we turn to the right what is the NR trend and what happens turning to the opposite side?
Cheers,
Sax
The question is:
during an autorotation at constant speed and considering a helicopter with a rotor turning CCW like the Agustas, if we turn to the right what is the NR trend and what happens turning to the opposite side?
Cheers,
Sax
Thread Starter
Joined: Apr 2006
Posts: 41
Likes: 0
From: Europe, Middle East, Far East and rarely USA ... so far !
What I personally think is that the trend in this situation is to increase turning to the right and decreasing when turning to the left... the opposite in case of CW rotor turning
Last edited by Sax412; 20th January 2009 at 15:39.
Joined: Jul 2001
Aviation Qualifications: ATPL(H)
Posts: 508
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From: UK
Leaving myself open for some heavyweight abuse here.........
The Nr will rise in turns in either direction due to load factor as GG correctly stated.
However, as the disc is tilted, there will be a transient increase or decrease in RRPM (CCW rotor - Nr increases transiently as rolled right) due to Vsquared effects on drag (and autorotative force) between advancing and retreating blades. The higher the airspeed, the greater the effect. Zero airspeed autorotation = no transient Nr change.
JJ
The Nr will rise in turns in either direction due to load factor as GG correctly stated.
However, as the disc is tilted, there will be a transient increase or decrease in RRPM (CCW rotor - Nr increases transiently as rolled right) due to Vsquared effects on drag (and autorotative force) between advancing and retreating blades. The higher the airspeed, the greater the effect. Zero airspeed autorotation = no transient Nr change.
JJ
Joined: Sep 2007
Posts: 217
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From: All over UK awaiting the dream.
LOL how numb.............titlt the disc forwards increase fwd speed and you will get a reduction of Nr the value of which will be proportional to the rate of application and the commensurate with the max value of reduced inflow angle. You also get an increased ROD [which is useful] and a reduced ground track distance. A useful technique for controlling increasing Nr without using the collective following a mishandled turn - in either direction.
Best Wishes
Best Wishes
