A question regarding the tail rotor dynamics.

[VanjaB]

Why does the Helicopter spin clockwise when collective is fully down?? Or rather why do I need to apply left rudder to keep the helicopter from spinning. (Sometimes not even holding the wheelbrake is enough) I understand that when you increase the collective you need to fight the torque forces but these forces try to push the helicopter anticlockwise so and so you need to apply right rudder.

[dahui]

because the blades dont have zero pitch when the pedal is in the middle. because you have to push the right pedal to far for hovering...

 

in the jetranger for example (PowerPedal is left but it doesnt play a role...)

hovering is left pedal, cruise is a little bit right...

Edited October 3, 2013 by dahui

[sobek]

Why does the Helicopter spin clockwise when collective is fully down??

 

Because your helicopter needs to apply very little torque to the main rotor to keep it turning in that configuration, yet the tail rotor is set to counter a lot more torque when the pedals are centered, so there is no balance of torques and the helicopter wants to turn.

 

It's the simple principle of actio and reactio.

[VanjaB]

Ahh I see, so the tail rotor is configured for a higher collective setting. Makes sense.

 

A followup question, although its not related to the Mi-8. Do modern helicopters (single rotor configuration) have some kind of electronic aid that adjusts the tail settings on the fly?

 

For example a pilot pulls up (or down) on the collective, and the flight computer adjusts the rudder input automatically.

 

Is this done in helicopters at all or is that a big no no?

[AlphaOneSix]

For example a pilot pulls up (or down) on the collective, and the flight computer adjusts the rudder input automatically.

 

This can be done in certain autopilot modes on some helicopters. Also, some helicopters do it mechanically so that any collective input automatically adds tail rotor input.. The Black Hawk, for example, does this.

[VanjaB]

This can be done in certain autopilot modes on some helicopters. Also, some helicopters do it mechanically so that any collective input automatically adds tail rotor input.. The Black Hawk, for example, does this.

 

Thanks for taking the time to answer. Was wondering about that because this is how its done on RC helicoptes as well, mechanically I mean. Sounds like an essential upgrade that would make piloting and especially landing much easier.