When practicing vortex ring.........
Thread Starter
Join Date: Nov 2007
Location: Where it rains a lot .....
Posts: 213
Likes: 0
Received 0 Likes
on
0 Posts
When practicing vortex ring.........
When practicing vortex ring
Is the speed recovery time effected wether you are going into wind or down wind ?????
Is the speed recovery time effected wether you are going into wind or down wind ?????
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.
I'd not do that too close to the ground. If you actually enter VRS, recovery may take some altitude to achieve.
Avoid imitations
Join Date: Nov 2000
Location: Wandering the FIR and cyberspace often at highly unsociable times
Posts: 14,573
Received 415 Likes
on
218 Posts
Was that VR? Looks more like plain old running out of power /overpitching after an unstabilised and too fast approach.
Join Date: Apr 2003
Location: 18 Degrees North
Posts: 699
Likes: 0
Received 0 Likes
on
0 Posts
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.
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.
Last edited by Camp Freddie; 28th Jun 2012 at 22:10.
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.
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.
Just imagine, you do that in IMC with no GS Indication...
skadi
Join Date: Sep 2011
Location: Honolulu
Posts: 12
Likes: 0
Received 0 Likes
on
0 Posts
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....
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....
Last edited by Nedkelly123; 29th Jun 2012 at 06:06.
Join Date: Aug 2001
Location: Cornwall
Age: 75
Posts: 1,307
Likes: 0
Received 0 Likes
on
0 Posts
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.
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.
Ah, Geoffers, the thought of all that delicious Italian pasta for supper! Though I prefer the suppers after a trip in a French sim
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!!
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!!
Last edited by Hummingfrog; 29th Jun 2012 at 07:50.
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.
Join Date: Jan 2001
Location: UK
Age: 70
Posts: 1,364
Likes: 0
Received 0 Likes
on
0 Posts
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.
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.