Tail Rotor

Question 1

What is the purpose of a tail rotor?

Answer 1

Anti-torque. Heading control in the hover. Balance in forward flight.

Question 2

What is tail rotor drift and how is it countered?

Answer 2

A drift towards the advancing side of the disc. Countered with cyclic.

Question 3

How does tail rotor drift occur?

Answer 3

The fuselage rotates in response to the torque reaction from the rotors.

There is no nose rotor. So the tail rotor provides counter-torque. This stops the rotation but sets up a sideways drift around the pivot point of the aircraft.

Question 4

What is tail rotor roll?

Answer 4

The effect of countering tail rotor drift. A couple is set up between the cyclic input (rotor head) and the tail rotor thrust.

The main rotor now has a horizontal component in the direction of cyclic input.

Question 5

What stops tail rotor roll?

Answer 5

The other couple that is set up between the vertical component of total rotor thrust and the weight which acts through the centre of gravity.