The pilot of the amateur-built aerobatic airplane stated that he planned to perform three touch-and-go landings. Prior to flight he used a stick he had previously calibrated to check his main fuel tank. His main fuel tank held 19 gallons, with 1 gallon unusable, and he did not store any fuel in his auxiliary fuel tank. He measured 5 to 6 inches of fuel on his stick, which he equated to approximately 6.5 gallons of fuel. About 15 minutes after engine start the pilot was completing his third touch-and-go landing when, on the upwind leg and at approximately 300 feet above ground level, the engine lost all power. The pilot attempted to turn around and land on the runway in the opposite direction of takeoff; however, the airplane impacted the airport ramp area and came to rest upright. Examination of the wreckage by a Federal Aviation Administration inspector revealed that the main fuel tank, including the clear fuel line leading from the tank to the fuel selector valve, was absent of fuel. The inspector and airport personnel did not notice any evidence of the fuel tank being compromised or any postimpact fuel spill.