THE COMMERCIAL PILOT WAS CONDUCTING A WHEEL LANDING TO THE ACTIVE RUNWAY. ON LANDING ROLL OUT, THE AIRPLANE STARTED TO VEER TO THE RIGHT. THE PILOT APPLIED LEFT RUDDER AND THE AIRPLANE WENT STRAIGHT FOR A SHORT DISTANCE AND VEERED TO THE LEFT. THE PILOT APPLIED FULL RIGHT RUDDER AND APPLIED POWER WITH NEGATIVE RESULTS. THE AIRPLANE EXPERIENCED AN ON GROUND LOSS OF CONTROL AND DEPARTED THE RUNWAY, NOSED OVER, AND CAME TO REST ON ITS BACK.