The pilot stated to the FAA inspector that he had an accident back in the 1960's. His back was injured. As a result of this, about 10 times a year, his legs will quit working and he will fall. On May 5, 2007, he flew his aircraft. On a latter flight that day, during the takeoff roll, he lost the use of his legs and could not control the rudders. He lost control of the aircraft and it turned over. He was trapped under the aircraft. Gas from the aircraft got on his body causing third degree chemical burns and he broke three ribs, and dislocated a shoulder. The pilot stated the aircraft was a Dominator by Rotor Flight Dynamics Inc. The pilot finished building the aircraft in February of 2007. The aircraft had a total of 6 hours on it. He had received dual instruction, but he did not have a pilot's license or a student pilot's license. The aircraft did not have an N registration number; however, he did have two sets of N registration numbers reserved. One of which he was planning to use on this aircraft. The pilot said the aircraft's weight was 350 lbs. One of the EMT personnel who attended to the pilot at the accident site stated to the FAA inspector that they have records showing the pilot having an accident in the same aircraft at the same airport in March of 2007. The FAA inspector did confirm with the pilot that the same thing happened in March. He was not hurt that time; however, the aircraft was damaged. He said he now knows that he lost the use of his legs at that time, but he did not realize it then. No mechanical abnormalities with the aircraft was reported by the pilot. A completed Pilot/Operator Aircraft Accident /Incident Report (NTSB Form 6120.1/2) was not received.