Hind Wobble

[Pjay22]

Hi All,

 

Just wondered if they'll implement the Hind 'wobble' that occurs during initial start up? Not major but would be cool.

 

Around 20secs into the video.

[Focha]

Not every helicopter (Hind) wobble like that. It seems to be either that the cyclic is not centered or the rotor is not balanced.

 

But every video I see, you see the Hind wobble like mad. xD

 

Edited August 13, 2020 by Focha

[Fri13]

Not every helicopter (Hind) wobble like that. It seems to be either that the cyclic is not centered or the rotor is not balanced.

 

If rotor would be so badly unbalanced, it would tear up the aircraft fairly soon.

[AlphaOneSix]

It's because the rotor blades are not all exactly the same distance/angle apart after sitting for a while. Some blades lead a bit, some blades lag a bit, depending on the angle of the rotor mast to the ground or how the rotor was tied down and if the blades moved independently for any reason. At startup, at a certain rotor speed, all the blades lead and lag to their proper angles, but before they get there, the rotor has an imbalance due to this uneven spread of the blades, which causes the wobble. The more imbalance, the more wobble.

 

If you could somehow keep all the blades at exactly 72 degrees from each other, there wouldn't be any wobble at all.

[Pjay22]

It's because the rotor blades are not all exactly the same distance/angle apart after sitting for a while. Some blades lead a bit, some blades lag a bit, depending on the angle of the rotor mast to the ground or how the rotor was tied down and if the blades moved independently for any reason. At startup, at a certain rotor speed, all the blades lead and lag to their proper angles, but before they get there, the rotor has an imbalance due to this uneven spread of the blades, which causes the wobble. The more imbalance, the more wobble.

 

If you could somehow keep all the blades at exactly 72 degrees from each other, there wouldn't be any wobble at all.

 

Great explanation :thumbup:

[Hueyman]

I second that ! And the viscosity of the lead/lag dampers, also depending on the temperature, have an effect on how quick blades resets themselves with centrifugal force.

 

The SA330 Pumas and similar fully articulated rotorhead helis also does that.

 

On the current DCS Mi-8, there is already something quite similar, yet not identical on first start up : instead of wobbling once per revolution, at every blade count you notice a light out of balance situation, that disappears as RPM rises to the nominal range and that are only preset at first start up of a newly loaded game.

[ThorBrasil]

Not every helicopter (Hind) wobble like that. It seems to be either that the cyclic is not centered or the rotor is not balanced.

 

But every video I see, you see the Hind wobble like mad. xD

 

 

This video happens the same oscillation as the first one. The difference that the side camera is more evident than the front camera, but both oscillate. :thumbup:

[Focha]

You guys are right, all helicopters wooble a bit, but those Mi-24 wooble a lot! In the R44 I flew the tail wooble like mad at idle power. But on the AS365, that was not really noticeable. But depending on the aircraft, even the same type would produce different woobles and vibrations, I flew a few AS350, more than 9, and there were some that wooble more than others. The rotor system of 350 and 365 is alike. Never flew the Puma or Super Puma.

 

Also, it can be the fact that the axis of the main rotor shaft on the Mi-24 2,5° tilted to the right. It can also help producing those woobles.