R22 No Push Stick Foreward.
Joined: Feb 2007
Posts: 6
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From: Directly under the Earth's sun....now
an enlightening experience
My worst and best flight involved a check ride before I took delivery of a new R22 for delivery to Northern Alberta. My check ride was fairly uneventful until the pilot checking me out decided it would be a good idea to check my "bush sense" and asked me to enter an extremely tight confined area (even for an R22) with tonnes of overhanging dead fall, and tonnes of tree stumps. I said no initially, however he explained exactly how he wanted it done and that he wanted me to at least make an effort so after a few dummy runs in we went. Pucker factor of about 8....
After that I think he just got bored and he decided to demo OGE zero speed auto's and wrapped it all up with a demonstration of Vortex Ring State at altitude. It was needless to say an enlightening experience, but not an enjoyable one. In the end it was nice to see what the aircraft could do but it also gave me a healthy respect for staying within the flight envelope. Who knows maybe that flight saved my life once or twice?
After that I think he just got bored and he decided to demo OGE zero speed auto's and wrapped it all up with a demonstration of Vortex Ring State at altitude. It was needless to say an enlightening experience, but not an enjoyable one. In the end it was nice to see what the aircraft could do but it also gave me a healthy respect for staying within the flight envelope. Who knows maybe that flight saved my life once or twice?
Last edited by rotarypilot; 21st February 2007 at 06:57.
Joined: Sep 2005
Posts: 385
Likes: 0
From: england
Hi guys,
as fixed wing PPL I quite fancy doing a PPL(h) at some point, and I am reading this thread with interest
- Can someone explain why sudden forward movements of the cyclic are so dangerous please?
as fixed wing PPL I quite fancy doing a PPL(h) at some point, and I am reading this thread with interest
- Can someone explain why sudden forward movements of the cyclic are so dangerous please?
Joined: Feb 2001
Posts: 603
Likes: 0
From: US
Can someone explain why sudden forward movements of the cyclic are so dangerous please?
Helicopters with a teetering rotor system can experience mast bumping in negative g. The results are usually unfavorable.
http://www.everything2.com/index.pl?node_id=1488804
Joined: Nov 2004
Posts: 1,334
Likes: 0
From: Cambridgeshire, UK
Kengineer-130,
I don't claim to be an expert, and certainly disregard my comments if an instructor chips in...
A helicopter cyclic movement initially controls the pitch/roll acceleration of the helicopter. The rotor responds quickly and the heli starts to swing, but it takes a while for the rate to build up. As the fuselage rolls or pitches the machine then becomes velocity control like a fixed wing. This is caused by the lag in rotor following heli, leading to an equilibrium at a fixed pitch or roll rate - basically the swash plate angle is now generating gyroscopic nutating forces. Once the heli starts to translate (or change its translational speed) flapback then leads to positional control on the cyclic.
Eventually the system will reach the attitude demanded, but the delay in response can lead to overcontroling hence reduced-g mast bumping (or PIO in hover). There is also the fact that the range of cyclic movement required for flapback (heli version of dihedral) increases stick sensitivity.
Actually a suprisingly good way to train your reflexes for the fine movements required is to thermal a glider. Being near stalling, while in a turn seems to make you much more aware of the aircraft feedback. It's been a little while since i flew anything though...
Mart
I don't claim to be an expert, and certainly disregard my comments if an instructor chips in...
A helicopter cyclic movement initially controls the pitch/roll acceleration of the helicopter. The rotor responds quickly and the heli starts to swing, but it takes a while for the rate to build up. As the fuselage rolls or pitches the machine then becomes velocity control like a fixed wing. This is caused by the lag in rotor following heli, leading to an equilibrium at a fixed pitch or roll rate - basically the swash plate angle is now generating gyroscopic nutating forces. Once the heli starts to translate (or change its translational speed) flapback then leads to positional control on the cyclic.
Eventually the system will reach the attitude demanded, but the delay in response can lead to overcontroling hence reduced-g mast bumping (or PIO in hover). There is also the fact that the range of cyclic movement required for flapback (heli version of dihedral) increases stick sensitivity.
Actually a suprisingly good way to train your reflexes for the fine movements required is to thermal a glider. Being near stalling, while in a turn seems to make you much more aware of the aircraft feedback. It's been a little while since i flew anything though...
Mart
Last edited by Graviman; 24th March 2007 at 15:07. Reason: Just checked this up in Prouty...
Joined: Nov 2004
Posts: 1,334
Likes: 0
From: Cambridgeshire, UK
Just reworded that last post, having looked it up in Prouty. This was more for my own sanity, since i like to make sure i understand such things.
I would be more than happy if anyone were to correct it, since it would also benefit my understanding.
Mart
I would be more than happy if anyone were to correct it, since it would also benefit my understanding.
Mart
