The owner/builder/pilot had recently constructed the home built ultralight vehicle. According to friends, he most likely had never ridden in an airplane & he believed it was possible to build & fly the ultralight with no instruction. According to the owner of a garage where the ultralight was built, several people had advised the pilot that flight lessons would be prudent, but he disagreed. Reportedly, the pilot had made taxi runs & had said that he was going to 'crow hop' the ultralight as his next step toward his first flight. However, after lifting off, the ultralight continued to climb to approximately 60 to 75 ft AGL. After clearing electric lines on the west side of the field, the ultralight was observed to begin a left yaw that continued until the vehicle had turned to an easterly heading. The wings had remained level until this point, then the vehicle entered a left roll, the nose pitched down & the ultralight crashed in a steep nose down, almost inverted attitude. The engine sounded normal & continued operating until impact.