On August 21, 2005, about 1400 Pacific daylight time, the wing of a Beech A36, N7226M, dragged the ground during takeoff at Healdsburg Municipal Airport (O31), Healdsburg, California. The owner/pilot was operating the airplane under the provisions of 14 CFR Part 91. The airline transport pilot and one passenger were not injured; the airplane sustained substantial damage. The cross-country personal flight departed Healdsburg at 1400, with a planned destination of Truckee, California. Visual meteorological conditions prevailed, and no flight plan had been filed. The approximate global positioning system (GPS) coordinates of the accident site were 38 degrees 39 minutes north latitude by 122 degrees 53 minutes west longitude. The pilot reported that during takeoff he rotated at 75 knots. Shortly after liftoff, he felt the airplane roll and yaw; he thought that he was encountering a wind shear. The pilot initiated corrective control inputs with the rudder, neutral aileron, and forward yoke pressure. The airplane attitude and flight path returned to normal, and the pilot retracted the landing gear. The pilot did not feel or hear the impact of the left wing tip and was surprised to see the damage during the climb phase of the flight. The pilot elected to divert to Napa County Airport, Napa, California, where he executed an emergency landing. In the pilot's written report, he stated that the airplane and engine had no mechanical failures or malfunctions during the flight.