Complex sentence: Many full-sized (and model) rotorcraft have mechanically interconnected main and tail rotors so that when changing main rotor speed (and hence yaw torque), the tail rotor follows suit to compensate.
Split into simpler sentences: Many full-sized (and model) rotorcraft have mechanically interconnected main and tail rotors. Thus, when changing main rotor speed (and hence yaw torgue), the tail rotor follows suit to compensate.