The pilot was practicing takeoff and landings when he extended the landing gear and heard the landing gear motor start while the airplane was on the downwind leg to runway 10 (2,738 feet by 50 feet, asphalt). The pilot noticed that the landing gear was not down during the landing flare. The airplane touched down on the runway with the landing gear retracted, and the airplane skidded about 500 feet before coming to a stop. The airplane received substantial damage when the airplane's firewall and underside skin were damaged. During the airplane's recovery, the landing gear control handle was placed into the down position and the landing gear extended when the master switch was placed into the on position. Post accident inspection of the airplane revealed no anomalies.