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Co-Axial and Tandem rotor systems


Guest rookie101
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Guest rookie101

Hello to all,

 

Sadly, this questions has been bothering me for sevaral days and I now feel the need to ask it. How does a helicopter with a tandem or coaxial rotor system yaw, because does not the tail rotor on, let say, an S-64 make the helicopter yaw from side to side. If this is true (and I am 99.9% sure it is) than how does a CH-47 or Ka-32 yaw. I was thinking (:o) that on both systems one blade would slow down while the other would mantain what ever speed it was going at which would cause the helicopter to naturally yaw whatever direction, but then that doesn't work for the Ka-32 :wacko:. All input is of course appreciated.

 

rookie

 

BTW- don't haze me too much on this if the answer is pretty obvious. The screen name says all.

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Hi,

 

You are quite right, the tail rotor on the S-64 is used for yaw control (in addition to anti-torque(countering torque of main rotor.).

In the case of the CH-47, it uses differntiial cyclic on the for and aft rotors to yaw. To yaw left, it will input left cyclic on the forward rotor and right on the aft rotor.

In the case of the Ka-32, it uses differential collective. Normally the collective is equal on both rotors and thus each rotor counters the torque of the other. If the collective of one rotor is made to be greater than that of the other, the torque in the rotor system is unbalanced and the fuselage will yaw one way or the other.

 

BTW-... if more people would just answer a question asked, rather than having some snide comeback, the world would be a better place. :)

 

Take Care.

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Guest rookie101
Hi,

 

You are quite right, the tail rotor on the S-64 is used for yaw control (in addition to anti-torque(countering torque of main rotor.).

In the case of the CH-47, it uses differntiial cyclic on the for and aft rotors to yaw. To yaw left, it will input left cyclic on the forward rotor and right on the aft rotor.

In the case of the Ka-32, it uses differential collective. Normally the collective is equal on both rotors and thus each rotor counters the torque of the other. If the collective of one rotor is made to be greater than that of the other, the torque in the rotor system is unbalanced and the fuselage will yaw one way or the other.

 

BTW-... if more people would just answer a question asked, rather than having some snide comeback, the world would be a better place. :)

 

Take Care.

 

Thanks for the explanation Darwin. :D

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