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-   -   When practicing vortex ring......... (https://www.pprune.org/rotorheads/489187-when-practicing-vortex-ring.html)

nellycopter 28th Jun 2012 18:54

When practicing vortex ring.........
 
When practicing vortex ring
Is the speed recovery time effected wether you are going into wind or down wind ?????

Lonewolf_50 28th Jun 2012 19:01

What altitude are you doing this practice at?

I'd not do that too close to the ground. If you actually enter VRS, recovery may take some altitude to achieve.

Anthony Supplebottom 28th Jun 2012 19:21

When practicing vortex ring .. don't inadvertently do this .......


ShyTorque 28th Jun 2012 19:28

Was that VR? Looks more like plain old running out of power /overpitching after an unstabilised and too fast approach.

Anthony Supplebottom 28th Jun 2012 19:31

Yep, looks like that. Just saying to be careful when recovering from the practice (especially you aren't so high).

Hummingfrog 28th Jun 2012 19:43

The helicopter doesn't know if it is into/cross/downwind so the answer to your question is no.

HF

hueyracer 28th Jun 2012 20:54

If you are IN VRS-no.

But trying to recover from it-it is different.

With tailwind it takes longer to get out of it again.

Always add at least another 500 ft if you are practicing this with a new student...

Hummingfrog 28th Jun 2012 21:04

Huey Racer


With tailwind it takes longer to get out of it again.
are you sure of that statement!!

HF

nellycopter 28th Jun 2012 21:26

I thought this might bring on some conflicting comments,

Hummingfrog 28th Jun 2012 21:49

It is a simple concept - does a helicopter fly relative to the ground or air?

HF

Camp Freddie 28th Jun 2012 21:50

I am on board with Hummingfrog, clearly the helicopter doesn't know or care if it's into wind or downwind, it's only interested in the relative wind, I think there are 3 points of interest here.

1) it's a matter of how it looks visually, into wind you are often moving backwards over the ground in order to get a good rate of descent in the incipient stage, whereas downwind you are still moving forward over the ground at the same point and that feels more normal .

2) while recovery clearly takes the same time, you are not so well placed downwind at the bottom of the recovery much nearer the ground if you run into a problem that may require an autorotation and engine off landing.

3) in my experience people are often shown the wrong technique for minimum height loss recovery, in particular they do not level the ship as they recover the airspeed through 30kts and as they pull power with the nose still down they accelerate the descent and lose far more height than they would otherwise.

Min 2000ft height is a good starting point I think with a student.

[email protected] 29th Jun 2012 04:59

It will take longer to recover if you have a 5 kt tail wind compared to a 5 kt head wind because you have to accelerate through the zero airspeed condition to get positive airspeed.

nellycopter 29th Jun 2012 05:42

Are you sure Crab....

skadi 29th Jun 2012 05:54


It will take longer to recover if you have a 5 kt tail wind compared to a 5 kt head wind because you have to accelerate through the zero airspeed condition to get positive airspeed.
For VR you should have 0 kt airspeed, so its no matter were the wind comes from....
Just imagine, you do that in IMC with no GS Indication...

skadi

Nedkelly123 29th Jun 2012 06:00

VR
 
I always thought that :
1. Establish Out of ground effect hover. Induced Air is pulled directly through the rotor system
2. As we descend we add upwind component which opposes the induced airflow of our OGE hover.
3. This results in Vortices being created from the blade root and moving outwards along the blade if more power is added.

To get out of the VR we need to clear the vortices. The most common is to gain airspeed forward... but this may not always be possible.

So a movement to the front, side or even backward sufficient to clear the vortices will help get out of VR... pull pitch and recover.

For training its any indication of airspeed....

fadecdegraded 29th Jun 2012 06:35

It will take more height and distance over the ground to recover from VRS downwind than it will by recovering into wind.
If in doubt try it but keep plenty of height on

Geoffersincornwall 29th Jun 2012 07:11

DON'T DO IT.........
 
...........IN THE HELICOPTER.......

If you are going to rehearse the recovery from VR (Settling with Power if you prefer) then do it in a simulator. You can crash all day and still go home for supper.

G. :ok:

Hummingfrog 29th Jun 2012 07:47

Ah, Geoffers, the thought of all that delicious Italian pasta for supper! Though I prefer the suppers after a trip in a French sim:ok:

Only ever saw "Vortex Ring" once - in a Whirlwind on the climb to 10,000ft sortie when in was demoed on the way back down - decided I would avoid it at all costs - at that height I couldn't tell if we had a head or tail wind - neither could the old Whirly 10;)

HF

Crab - I am surprised at your answer - head and tail winds are only with reference to the earth not the the mass of air the helicopter is flying in!!

[email protected] 29th Jun 2012 08:16

Yes, and if you are moving backwards within that mass of air ie with a 5 kt tail wind, and you want to move forwards in that mass of air ie to achieve a 30 kt headwind, then it will take longer to achieve than if you were already moving forwards in that mass of air ie a 5 kt headwind. It doesn't matter what the earth beneath you is doing, it's all about TAS and going from a negative to a positive rather than from a positive to a larger positive.

Helinut 29th Jun 2012 09:26

In my book, Hummingfrog is right in what he says, but that is not quite the whole story. The helicopter is controlled and manipulated by the pilot, who uses visual cues to decide what to do and when.

As Crab suggests, a downwind demo of VRS will be likely to involve starting at a negative speed hover wrt the air (or at least a lower airspeed than into wind). There seems to me to be 2 possibilities:

The recovery is standard (i.e. does not vary depending upon the relative wind).
In this case, a "standard" amount of nose down will initiate the recovery. But with downwind the pilot will wait longer to see the positive (30+ kts) IAS that he requires before doing the rest of the recovery. Because he waits longer while descending, the aircraft will descend further.

The recovery is varied to take account of relative wind
Knowing that he is downwind with lower/negative air speed the pilot chooses a larger nose down attitude when downwind. That has the same net effect that the total descent will be greater than for into wind, before positive IAS is achieved.


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