The pilot performed several maneuvers in the local area during a "phase 1" flight test. The pilot returned to the departure airport where he completed two normal landings on runway 04 (2,340 feet by 200 feet, grass) and was to perform a third landing. The pilot stated that during the third landing flare, the airplane sink rate was "too fast" and the nose wheel contacted the runway. The airplane then nosed over. The airplane was configured with full flaps. Damage to the airplane included a buckled fuselage and vertical stabilizer. The pilot was uninjured. The pilot stated that engine power should have been applied to control the sink rate. Examination of the accident site revealed a ground scar in a field about 130 feet from the runway threshold or about 30 feet from the runway edge. The ground scar was consistent with the airplane's initial touchdown point. The pilot said that he would usually use an aim point that was about 100 feet past three yellow cones that delineated each side of the threshold.