Vortex Ring State...

[Anatoli-Kagari9]

It had been a year since I last played with the UH-1H... so I rushed comparing how easily I could get it into and out of VRS using the wrong techniques...

 

It surprised me that I need more than 3000fpm descending to get VRS ? Is it really that permissive IRL too ?

 

 

[Ramsay]

Last time I entered VRS in the DCS Huey I had a descent rate of approx. ~850 fpm in a stop turn while using an aggressive amount of collective, easing off on the collective and bank allowed me to recover safely.

 

Requirements for VRS are

 

• speed below ETL

• descent rate more than 300 fpm (R22, exact value depends on rotor diameter, aircraft weight and air density)

• 20-100% power/torque applied

 

Note: The lighter the helicopter and larger the rotor, the easier it is to enter VRS.

 

IIRC the consensus on a helicopter forum was that realistic values for entering VRS IRL was 40-60% TQ and 0.65 of the downwash.

RL pilots are trained to use lower values when flying to add a safety margin that allows for instrument lag, pilot response, etc.

 

 

 

Edited January 19, 2021 by Ramsay

[Lurker]

On 1/13/2021 at 3:44 PM, jcomm said:

It had been a year since I last played with the UH-1H... so I rushed comparing how easily I could get it into and out of VRS using the wrong techniques...

 

It surprised me that I need more than 3000fpm descending to get VRS ? Is it really that permissive IRL too ?

 

 

 

Did you have any ETL? (Translational Lift) The Huey is quite forgiving with VRS if you have at least some translational speed. It only get's dangerous below 30-40kph. 

[Anatoli-Kagari9]

@Lurker, I made sure I was bellow 30 kts, close to 0 kts...

 

It did fall into int, but took some work

 

Then you really can't get out unless you apply the proper procedure.

[FADEC]

To get in to Vortex Ring State, or Settling with Power you need to check these three boxes,

 

Speed Below ETL 16-24 Knots (This is not speed across the ground, but wind through the rotor system)

Rate of Decent greater then 300 FPM

And Power applied 20-80%

 

For Single Rotor Helicopters the primary corrective action use to be forward cyclic to fly out of it, now lateral cyclic  is the new "hotness" for corrective action.

[iFoxRomeo]

54 minutes ago, FADEC said:

To get in to Vortex Ring State, or Settling with Power you need to check these three boxes,

 

Speed Below ETL 16-24 Knots (This is not speed across the ground, but wind through the rotor system)

Rate of Decent greater then 300 FPM

And Power applied 20-80%

 

For Single Rotor Helicopters the primary corrective action use to be forward cyclic to fly out of it, now lateral cyclic  is the new "hotness" for corrective action.

VRS =/= Settling with power

 

jcomm with 3000fpm you should be beyond vrs already

[FADEC]

Yes VRS = Settling with Power.

 

and as long as you are above ETL all sins are forgiven, VRS / Settling with power wise.

[iFoxRomeo]

27 minutes ago, FADEC said:

Yes VRS = Settling with Power.

 

and as long as you are above ETL all sins are forgiven, VRS / Settling with power wise.

It is often confused, but it is not the same.

You don't need Vortex Ring State to settle with power.

You can settle with power with just -100ft/min, but that is not VRS then.

Settling with power means that you touch/hit the ground because you don't have enough engine-power to reduce your rate of descent in time.

Vortex ring state is a state of the rotor where the airflow is partially or fully "reversed".

A vortex ring state can lead to a settle with power, depending on the height you have. You can enter a VRS at 5000ft and exit the VRS at 4000ft without hitting the ground.

 

Fox

[FADEC]

Sorry Fox,

 

Settling with power has nothing to do with hitting the ground.   Vortex ring state is sometimes referred to as settling with power. The Federal Aviation Administration (FAA) sees these terms as synonymous.  If the helicopter is settling in its own rotor wash (I.E Vortex Ring State) that would be settling with power.  If I don't have enough engine power to reduce my rate of descent in time that that either a lack of performance planning, or potentially mushing if I'm flying like a dumb ass.

[iFoxRomeo]

17 hours ago, FADEC said:

Sorry Fox,

 

Settling with power has nothing to do with hitting the ground.   Vortex ring state is sometimes referred to as settling with power. The Federal Aviation Administration (FAA) sees these terms as synonymous.  If the helicopter is settling in its own rotor wash (I.E Vortex Ring State) that would be settling with power.  If I don't have enough engine power to reduce my rate of descent in time that that either a lack of performance planning, or potentially mushing if I'm flying like a dumb ass.

Well, the FAA used "Settling with Power" together with VRS. But even the FAA differentiates nowerdays. And luckily the Helicopter Flying Handbook is no Bible that can't be changed.

Quote:

https://www.faa.gov/regulations_policies/handbooks_manuals/aviation/helicopter_flying_handbook/media/hfh_ch11.pdf

"Vortex ring state (formerly referenced as settling-with-power) describes ..."

 

And the Canadians say the following in their Helicopter Flight Training Manual:

https://www2.tc.gc.ca/eng/civilaviation/publications/tp9982-exercise26-973.htm

Quote:

"There are some uninformed pilots who use “settling with power” to describe vortex ring, in fact some publications use the terms interchangeably. Confusion results when symptoms are related that do not describe true vortex ring but rather describe “settling with insufficient power”. This may occur when a pilot attempts to arrest a rapid, low power descent only to find that he has insufficient power available to bring the helicopter to either a hover or a no-hover landing without exceeding the engine limits. However, this is not a vortex ring situation. "

 

Fox

[admiki]

It's nice how people think that all that came from USA must be God given present to humanity.

iFoxRomeo is right VRS=/=Settling with power

https://www.youtube.com/watch?v=ehV9vLnBICE&t