mi-8 helicopter Landing

[Kowshik]

During doing approach of MI-8 helicopter why helicopter judders on short finals. What is the remedy of this??

[tusler]

This normal vibration and almost all helicopters go through it at a certain speed when they transition from flight to hover.

Check this out:

 

 

[Hammer1-1]

Slow down nice and smoothly while pulling back on the collective and holding altitude. Practice doing this in any helicopter and you'll be proficient in landing in no time and you can also minimize the vibrations you feel when transitioning back from fwd flight to hover.

[Hiob]

With a certain forward speed, the rotor disc acts more like a wing than like a "fan". Transitioning from one state to the other gives those vibrations. Both in acceleration and deacceleration.

[tusler]

On 7/11/2021 at 7:34 AM, Kowshik said:

During doing approach of MI-8 helicopter why helicopter judders on short finals. What is the remedy of this??

Sir, I have found this site that has helped me understand what make a Heli fly and help with controlling it. I hope it helps you too.

 

[Kowshik]

Is there any chance that with those vibration i will fall into vortex ring state?? Or its just because of transverse flow effect/loosing ETL. Can I get the explanation?

[tusler]

I  know from experience that if I am OGE and the vib's start and I let that VSI dip to 500, i will be in a ring state real quick, so if you can keep it just on the edge of the vib's as you are coming in to land with just a little fwd speed it will keep you out of VRS.

The Hind is even worse because it has no vibration to let you know, its real smooth and quiet and then all the sudden I am falling out of the sky. LoL

Edited July 12, 2021 by tusler

[Hiob]

12 hours ago, Kowshik said:

Is there any chance that with those vibration i will fall into vortex ring state?? Or its just because of transverse flow effect/loosing ETL. Can I get the explanation?

Before the shuttering, above 50-70 kph you're safe from VRS. Beyond it, you need to add collective and watch the VSI closely. Descent with VSI 1-2, max 3.

[Kowshik]

2 hours ago, Hiob said:

Before the shuttering, above 50-70 kph you're safe from VRS. Beyond it, you need to add collective and watch the VSI closely. Descent with VSI 1-2, max 3.

but on the last day I saw that at 50-60 kph helicopter started shuttering .VSI was 2-2.5 and as I add more power the shuttering increased. Can you plz tell me whether it was normal or symptoms of VRS.

[Hiob]

I don't have the exact values at the top of my head.

In general - with the Mi-8 there is no way to avoid it. It is normal. In acceleration/take-off you can "push/rush through it", but in final approach there is no way since you need to do everything slow and feely.

The increase of collective is not to avoid or reduce the shuttereing, but to counter the loss of lift that comes shortly after it.

Try a shallow fixed-wing-like landing - that is the easiest way and you'll probably don't need to be that careful with the collective since you never loose ETL.

In a vertical landing ALWAYS keep a close eye on the VSI and counter any change immedietly with small adjustments of collective.

The Dangerzone (when the shuttering kicks in) is, when transitioning from forward flight into a hover without groundeffect (when you come to a stop midair with the intend to land vertically) and then the shuttering is your first last and only hint (except watching your instruments) to be on high alert regarding VSI.

 

Watch the youtube tutorials of vsTerminus on Takeoff/Landing and Hovering. They are very good and teach everything you need to know way better than I can describe here.

[Kowshik]

3 hours ago, Hiob said:

I don't have the exact values at the top of my head.

In general - with the Mi-8 there is no way to avoid it. It is normal. In acceleration/take-off you can "push/rush through it", but in final approach there is no way since you need to do everything slow and feely.

The increase of collective is not to avoid or reduce the shuttereing, but to counter the loss of lift that comes shortly after it.

Try a shallow fixed-wing-like landing - that is the easiest way and you'll probably don't need to be that careful with the collective since you never loose ETL.

In a vertical landing ALWAYS keep a close eye on the VSI and counter any change immedietly with small adjustments of collective.

The Dangerzone (when the shuttering kicks in) is, when transitioning from forward flight into a hover without groundeffect (when you come to a stop midair with the intend to land vertically) and then the shuttering is your first last and only hint (except watching your instruments) to be on high alert regarding VSI.

 

Watch the youtube tutorials of vsTerminus on Takeoff/Landing and Hovering. They are very good and teach everything you need to know way better than I can describe here.

thanks