Hello all,
I am from Canada, spend most of my time looking down a long line, and flying in the mountains. I find myself in the kind of work environment that frequently lends itself to vortex ring situations. I am not an instructor, but I can perhaps throw a few ideas on the table that I wish I knew when I was starting out. Some of this will be redundant for people, and I apologize for any inaccurate terminology that may be used in current instructor speak.
It's important that students have a thorough understanding of exactly what Vortex Ring is. They need to know:
-What 3 factors you need to get into it,
-How to recognize it,
-How to get out of it.
I just wanted to elaborate a bit on some of these points and add to the concepts that the basic exercise teaches.
To get into it we need:
-Little or no airspeed,
-Rate of decent,
-And using power.
If you don’t have all 3 present no worries right? Well not always!.....Up flowing air gives you the same situation as being in a descent. Hovering at the top of a ridge can be brutal if the air is screaming up the slope at you from below. First off you are surprised at how little power you need to hover, you feel the mushiness of the tail, pull a bit of power and all of a sudden it gets real ugly. Same mechanics as the practice scenario, but different causes and your not 2000' off the ground!
Next part would be on how to recognize it. Most will talk about shakes and shudders, tail is all over the place etc..All very important of course, but the reality is that if you are on very short final and it gets that bad, you are in big trouble unless you make immediate and drastic action to recover.
In production work your going as fast as practical (not possible), floating in on minimal power and pulling power on very short final. Unless your SURE that you have no V.R. concerns its always good to do a little check with the collective just before the final pull. This is the crucial part... when you do this your looking to see how the helicopter is reacting and how it feels under your ass. If all is good you should feel HEAVIER in your seat when you pull a bit of collective. If your anywhere close to entering V.R. you will not get that "heavier" feeling as your weight will stay neutral. If your closer to V.R. you will feel lighter in your seat...all this happens WELL before you begin to notice the usual signs of V.R. that everyone talks about.
Now put this into the hovering on the top of the slope scenario previously mentioned. Your hovering 40' off the trees (or your longline load is 40' off the trees) trying to decide if your going in or not. Your at a low power setting due to upflow air, make sure you have some air under you so you can abort if necessary and give the collective a bit of a pull, are you heavier or lighter in your seat?
Finally a few comments on how to get out of it. We are all well versed on that one, I just wanted to expend a bit on the practice scenario that we all learn with. The reality is that if it happens unexpectedly at 100' or less, there is not a lot of room to work with. Another reality is that unless your in full blown V.R., it doesn’t take much to get out of it. Generally just getting out of your downwash by moving a few rotor widths will do it. (try to go crosswind if you know your downwind as it started). What if your are already below treeline going into a pad and dont have the room to maneuver? One thing that can help is to stir the cyclic in a circle. This disperses your downwash a bit and can help a lot in the recovery.
Awareness that you are working in conditions conducive to V.R. , early detection followed by swift and accurate recovery techniques is what its all about concerning V.R.
The emphasis though should be on awareness and detection.....all the recovery techniqes in the world wont help a guy that repeatedly stumbles into in unaware.....he wont live long or he will be so scared after the first time he will have a hard time in a production work environment and will be quick to shut it down as he gets out of his comfort zone.
Conditions that are most conducive to V.R. are working in the bush with light and variable winds. You don’t always have the luxury of any form of wind indication (no water, leafy trees etc). If you want to be quick in these conditions you need tools to detect early V.R., and be comfortable with rapid recovery methods. In conditions like this the "collective check how does it feel in the seat thing" allows you to stay well ahead of the game. Always do the check early enough to get out of it if it doesn’t feel good. This kind of thinking allows you to work downwind, and in a variable wind condition with confidence and swiftness in a production environment.
Can you tell that I am sitting on a fire contract and its pissing rain? Too much time on my hands..
Thanks for reading my ratings....just wanted to offer suggestions on how to teach a new pilot to think about the whole concept and bring it a little closer to the ground so to speak.....
Signed;
Dammyneckhurts