The pilot stated that he was practicing takeoffs and landings in the airport traffic pattern. After takeoff, he noted that the air was very turbulent, and decided to land. The pilot made two landing attempts, and during the third attempt, the airplane landed long and overran the runway. The airplane traveled over an embankment, contacted several logs, nosed over, and came to rest inverted. Post-accident examination revealed substantial damage to the fuselage, left wing and vertical stabilizer. The pilot reported no preaccident mechanical malfunctions or failures that would have precluded normal operation.