The pilot was practicing a soft field takeoff. As the airplane accelerated the nose lifted more than anticipated and at a lower airspeed. The airplane drifted left off the runway surface and the pilot decreased power and attempted to correct the heading change with rudder, but the airspeed was too low for the rudder to be effective. The airplane struck a precision approach path indicator (PAPI) assembly and the pilot brought the airplane to a stop. The pilot determined he had incorrectly set the flaps to the second notch (full down) instead of the first notch specified in the pilot’s operating handbook, which he said contributed to the conditions leading to the loss of control. He further stated there were no mechanical anomalies with the airplane that contributed to the accident. The airplane sustained substantial damage to the right wing.