Rudder trim. I have a Nexstar thats a complete rebuild. On the maiden, it was trying to turn left on takeoff. I'm used to seeing this from prop torque, so I didn't think much of it. After trimming and landing, I noticed the ailerons trim position was trying to roll the plane to the left. With the dihedral wing, this aileron trim was compensating for rudder! On the next flight, I slowly took out the aileron trim and compensated with rudder. After a few trials, the plane now tracks very nicely on takeoff.

Most of us forget that with the large dihedral wing, the rudder and ailerons are very difficult to distinguish between when trimming. Next time you go up, have your instructor either add right aileron trim or remove left aileron (depending on what you've got set up), and then compensate with left rudder. Just a few clicks at a time and see if this improves your ground handling on takeoff.

Brad