tail rotor drift

tail rotor drift

tail rotor driftclick for a larger image
The front component of the torque couple and tail rotor thrust (two forces) cause the helicopter to drift to the right.
tail rotor drift
This view is from the rear of the helicopter. A couple is produced by the horizontal component of total rotor thrust and tail rotor thrust causing a rolling tendency to the left.
A side force produced by the tail rotor which, unless corrected, causes the helicopter to move sideways on the ground. The main rotor thrust is offset to produce a side thrust to correct for the tail rotor drift. This tendency must be corrected by moving the cyclic to the direction opposite to that of the drift so that the disc tilts slightly and stops the drift. The other method for correcting tail rotor drift is either to have a tilted mast or the use of bias in the cyclic control mechanism. Also known as a translating tendency. See also tail rotor roll.