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HeliTorque :: View topic - direction or opposite direction of torque rotation?
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HeliTorque Forum Index » Ground School

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direction or opposite direction of torque rotation?
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chopperjockey
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PostPosted: Fri Sep 25, 2009 10:18 pm    Post subject: direction or opposite direction of torque rotation? Reply with quote

The following question appears in a well known question bank.
Your answers please? and why.

A decrease in pitch angle of the tail rotor blades on a helicopter:

A) Causes the tail to pivot in the opposite direction of torque rotation around the main rotor axis

B) Is required to counteract main rotor torque produced by takeoff RPM

C)Causes the tail to pivot in the direction of torque rotation around the main rotor axis

D) Affects main rotor RPM
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PostPosted: Sat Sep 26, 2009 12:41 am    Post subject: Ground School Reply with quote

Ooooo. Tricky question. In order to answer correctly, one must understand what is meant by torque rotation. Torque is "to twist", "to turn", "to spin".
The rotor blades torque is in the same direction as the main rotor blades turn! The Anti-torque pedals are so named because they provide thrust against the effects of engine torque.

A) I would think this one.

B) Nope. We INCREASE pitch anytime power is increased

C) Don't think so. Decreasing pitch, reduces TR thrust, causing the copter to yaw in a direction opposite to that of the turning rotors (torque rotational direction)

D) However, this is also true! Since the tail rotor is coupled to the TR transmission then via shaft to the main engine transmission, any increase or decrease in pitch (load) of the tail rotors is transmitted to the engine, and rpms change accordingly. Left pedal settle, right pedal rise! (counterclockwise rotor system)

CONFUSION FACTORS: If one interprets torque rotation as the direction caused by the "effects" of the engine, then (C) would become the correct answer.
Since (A) and (C) are direct opposites, one MUST be the correct answer.
Answer (D) is a confusion factor no matter how you look at it.

That is why the correct answer lies only in the mind of the person who prepared the question!

Hate tests. Laughing
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