On July 31, 2004, at 1930 central daylight time, an amateur-built Stamsta Wittman Tailwind W10, N917WT, built and piloted by a private pilot, was substantially damaged while attempting to land on runway 27 (2,223 feet by 30 feet, dry asphalt) at the Waunakee Airport (6P3), Waunakee, Wisconsin. Visual meteorological conditions prevailed at the time of the accident. The local flight was operated under the provisions of 14 CFR Part 91 without a flight plan. The pilot reported no injuries. The flight departed 6P3 at 1830. The pilot reported that when he turned onto final approach the airplane was positioned about 500 feet above ground level (agl) with an airspeed indication of 80 miles/hour. The pilot stated that he noticed the airplane was too high while he crossed-over the approach end of the runway and that the "airspeed was at stall [speed]." The pilot stated he responded by lowering the aircraft's nose and increasing engine power. The pilot reported the increase of engine power "did not respond until nearly on the runway." The pilot stated the airplane "landed hard" and the main landing gear collapsed.