How does yaw work?

[MetaMarty]

I love the complexity of this simulation. I just can't seem to find an answer to this generic coaxial rotor question.

 

Given the fact that there is no tailrotor, I figured the only way that yaw could work would be to initiate some kind of differential torque in the rotors. However, looking at the pictures of the rotor hub, it seems that both swashplates are interconnected with bolts, which would make independant movement impossible. I might be mistaken, but the only way differential torque would work as far as I know, is to lower one swashplate and raise the other one. This would maintain the cyclic configuration and transfer weight from one rotor the other.

 

Although the blade pitch is visible, it looks like the swashplates are not animated in the simulator, so I can't study the behaviour while moving the flight controls.

 

What am I missing here?

[Grodin]

I love the complexity of this simulation. I just can't seem to find an answer to this generic coaxial rotor question.

 

Given the fact that there is no tailrotor, I figured the only way that yaw could work would be to initiate some kind of differential torque in the rotors. However, looking at the pictures of the rotor hub, it seems that both swashplates are interconnected with bolts, which would make independant movement impossible. I might be mistaken, but the only way differential torque would work as far as I know, is to lower one swashplate and raise the other one. This would maintain the cyclic configuration and transfer weight from one rotor the other.

 

Although the blade pitch is visible, it looks like the swashplates are not animated in the simulator, so I can't study the behaviour while moving the flight controls.

 

What am I missing here?

 

I don't have a clue about choppers... But i'd say changing blade pitch in relation to the other rotor would make this rotor give more lift than the other one thus yawing the chopper.. But what do i know ^^

[AlphaOneSix]

Nevermind, I was wrong. :(

Edited December 24, 2008 by AlphaOneSix

[RvETito]

Incorrect, the swashplates are fixed for the rotormast, they don't move up and down, only tilt. Those are the two sliders that move up-down together (collective) or differentialy (pedal).

 

Hang on, I'll look for a pic to show u.

Edited December 24, 2008 by =RvE=Tito

[MetaMarty]

Incorrect, the swashplates are fixed for the rotormast, they don't move up and down, only tilt. Those are the two sliders that move up-down together (collective) or differentialy (pedal).

 

In my model helicopter, the collective moves the entire swashplate up and down and the swashplate is not fixed to the shaft. I would not see in what other way you could increase the pitch collectively.

 

Differential torque, as I see it, could only be created by moving the swashplates up and down independant from one another. But looking at the picture on the frontpage of the manual, it looks like the swashplates are pretty much connected to eachother by rods. This would totally inhibit independant movement.

[RvETito]

My mistake here, the good old Ka-32 legacy :)

 

The two swashplates indeed slide up and down but only together, as you noticed the rods connecting them. They form the lower slider. The upper slider is on the top of the rotormast and is moving up-down by push rods inside the inner driveshaft. So for differential control the two swashplates move in one direction while the upper slider moves in the other. Note that the lower rotor blades pitch can be changed only from the swashplate (one link) while there are two on the upper rotor- one from the upper swashplate and one from the arm connected to the pushing rod, coaxial to the driveshaft. Look at this pic:

Edited December 24, 2008 by =RvE=Tito

[MetaMarty]

Ah, now I understand. I missed the upper part of the hub. Some feat of engineering.

 

This also poses some interesting limitations on the flight envelope. I figure that using rudder pedals could be quite dangerous in high-collective situations, as it could push one of the rotors to dangerously high AOA.

[RvETito]

No limitations on pedal input for such reasons, only for highspeed forward flight as a blades intersection precaution. The static adjustment of the rotormast (flight controls rigging) is such that the differential pitch should not change the overal rotor lift, only to distribute it between the two rotors. Even at maximum collective the pilot can apply maximum pedal (either).