According to the student pilot, he reported that while in a hover prior to departure, he attempted a 360-degree right pedal turn. About 180 degrees into the turn, the rotation speed started to increase. The pilot thought his reaction to the increased rotation speed was not as decisive as it should have been, which resulted in the helicopter departing controlled flight. The pilot stated that he did not press on the left pedal; instead he released pressure on the right pedal. The helicopter came to rest upright after impacting the ground, which resulted in substantial damage to the tail rotor drive shaft and boom. The pilot reported no preimpact mechanical malfunctions or failures with the helicopter that would have precluded normal operation.