Question on downwind autorotations
Thread Starter
Joined: Jan 2008
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From: ireland
Question on downwind autorotations
Greetings folks,
I was talking to a friend of mine recently who was telling me that downwind autorotations are practised by certain schools. I had never heard of the practise, and wasn't sure if he was having me on.
However, he insisted that they were possible by carrying out the following movements:
Enter autorotation as per usual, except in a downwind heading. Once you begin to flare at the end of the auto, instead of applying pedal to keep the machine straight, (as you would in a normal auto) you let the torque rotate the helicopter around 180 degrees, where you then apply pedal and some forward cyclic to arrest your downwind speed, and carry out a cushioned landing with collective as per usual.
I was arguing that the rotation from downwind to upwind would result in a low rpm situation as at some point your airspeed would drop to zero in the transition from 'backwards' to 'forwards' flight, and not enough time to bring it around fully into wind.
Has anyone ever heard of this procedure? There is a pint riding on this by the way!
I was talking to a friend of mine recently who was telling me that downwind autorotations are practised by certain schools. I had never heard of the practise, and wasn't sure if he was having me on.
However, he insisted that they were possible by carrying out the following movements:
Enter autorotation as per usual, except in a downwind heading. Once you begin to flare at the end of the auto, instead of applying pedal to keep the machine straight, (as you would in a normal auto) you let the torque rotate the helicopter around 180 degrees, where you then apply pedal and some forward cyclic to arrest your downwind speed, and carry out a cushioned landing with collective as per usual.
I was arguing that the rotation from downwind to upwind would result in a low rpm situation as at some point your airspeed would drop to zero in the transition from 'backwards' to 'forwards' flight, and not enough time to bring it around fully into wind.
Has anyone ever heard of this procedure? There is a pint riding on this by the way!
Joined: Jun 2006
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From: Can't see for cloud
mmm, from what you have described, the idea of turning 180 in the flare doesn't sound very appealing as you may be travelling backwards when you touch the ground. I know a few instructors and I haven't heard that one.
Thread Starter
Joined: Jan 2008
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From: ireland
Where does the torque come from if you are autorotating?
Maybe a confusion with a similar technique for a downwind "quick-stop" practiced by some instructors (mainly US?).
TT
TT
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From: Redding CA, or on a fire somewhere
downwind "quick-stop" practiced by some instructors (mainly US?).
Guest
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From: EU
The torque reaction is from the engine; so if the needles aren't joined lifting lever will not cause usual torque reaction: In fact a lever pump may cause the fuselage to go in the direction of the disk due to increased friction. Similarly, "letting pedal go" will allow the fuselage to turn with the disk: the thing you would usually be trying to avoid at the end of an autorotation.
Whether you would have energy to arrest the ROD, and groundspeed and suffer the loss of RRPM as you push cyclic forward into wind, begs the question of why you'd make life so hard.
I can't imagine anyone doing this in an R22 and that is what most schools use.
Whether you would have energy to arrest the ROD, and groundspeed and suffer the loss of RRPM as you push cyclic forward into wind, begs the question of why you'd make life so hard.
I can't imagine anyone doing this in an R22 and that is what most schools use.
Last edited by PPRuNeUser129638; 1st October 2009 at 17:14.
Guest
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From: EU
Yes, it's in the JAR syllabus, but involves 180 degree turn with airspeed at height. No pedal turn as discussed here.
I didn't have the impression that it was normal quick stop practice in the US, but have heard it suggested as a quick stop method: perhaps a further confusion with demonstration of limited cyclic control downwind.
I didn't have the impression that it was normal quick stop practice in the US, but have heard it suggested as a quick stop method: perhaps a further confusion with demonstration of limited cyclic control downwind.
Avoid imitations
Joined: Nov 2000
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From: Wandering the FIR and cyberspace often at highly unsociable times
I think the person originally telling this tale was talking through his back passage. If he wasn't at the time, he would probably be doing so after the ensuing accident...
From a closed down engine, there is no torque to use, only transmission drag.
From a closed down engine, there is no torque to use, only transmission drag.
Joined: May 2005
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From: All over
This is a technique that we have just mastered whilst bored waiting for some new students to walk in the door.
Entry auto as normal reduce airspeed back to zero, pedal turn 180 and apply aft cyclic estimate backward speed to around 50 kts look out as normal for the flare height, commence flare by pushing forward on the cyclic. Hold flare until zero speed. There no problem with tail rotor striking the ground as this is a backward flare ensure no run on speed to avoid spade end of skid digging in.
Its sounds dodgy but its not that hard to perfect
Entry auto as normal reduce airspeed back to zero, pedal turn 180 and apply aft cyclic estimate backward speed to around 50 kts look out as normal for the flare height, commence flare by pushing forward on the cyclic. Hold flare until zero speed. There no problem with tail rotor striking the ground as this is a backward flare ensure no run on speed to avoid spade end of skid digging in.
Its sounds dodgy but its not that hard to perfect
Joined: Oct 2007
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From: New Zealand
Yep let me know too as I'd love to see this as well. Early on in my flying I did 2000hrs in a Robbie instructing and believe me it won't work unless you're one of those, 1 in a million pilots, that can do anything. And if it did work, I bet you wouldn't do it again as it would be quite a ride!!!!!!!!!
Good luck to all practicing this one. Make sure your life insurance is up to date.
Good luck to all practicing this one. Make sure your life insurance is up to date.
Joined: May 2005
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From: All over
I was first shown this by an extremely experienced / crazy pilot. I then progressed on to rearward flight quick stops and them bit the bullet on an old 22 with less than 5 gallon and 1 pob I have not tried in a 44 yet dont want to bend it.
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From: West Wales and Zug, Switzerland
I must ask the question, why whould you want to do this. If the !!!! hits the fan and the donkey does stop simple auto to the ground would be enough.
Or is it so bad you need to be looking for a Darwin award.
Or is it so bad you need to be looking for a Darwin award.
Last edited by Jarvy; 1st October 2009 at 20:46.
Passion Flying Hobby Science Sponsor Work
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From: Belgium
180 degree flare
I have trained these advanced techniques in aug-2008.
Was quite surprised it is possible (with a R44).
Basically it is a "turning flare".
But I consider this a quite tricky maneuver
1. Blade almost "touch" the ground because one is speeking of a quite steep low level turn. So turn should be managed quite precisely.
2. Rolling out of turn and touching down is delicate to avoid lateral movement and risk of roll over, more tricky than just leveling the heli in a straigth line.
Personally I think a 90 degree is more manageable. Technique can also used to avoid a last minute obstacle on the intented landing spot, for instance a cable detected lately.
d3
Was quite surprised it is possible (with a R44).
Basically it is a "turning flare".
But I consider this a quite tricky maneuver
1. Blade almost "touch" the ground because one is speeking of a quite steep low level turn. So turn should be managed quite precisely.
2. Rolling out of turn and touching down is delicate to avoid lateral movement and risk of roll over, more tricky than just leveling the heli in a straigth line.
Personally I think a 90 degree is more manageable. Technique can also used to avoid a last minute obstacle on the intented landing spot, for instance a cable detected lately.
d3