The pilot reported that he was performing high speed taxi testing of his tailwheel-equipped amateur-built airplane. During one of the high speed taxi runs the airplane inadvertently became airborne. The pilot stated that he attempted to land, but then decided to go airborne. He stated that he climbed to an altitude of about 3,000 feet and flew for approximately 40 minutes before returning to land. He stated that during the landing he was fast because he was attempting a wheel landing. He said that the airplane bounced and the airplane came back down hard. The airplane's retractable main landing gear collapsed and the airplane skidded to a stop on its belly. Examination of the airplane revealed that the eight landing gear attach bolts had pulled loose from the wing structure. The landing gear penetrated through the upper surface of the wing.