protective fences around the spectator stands. >> reporter: these are 70-year-old world war ii fighter planes, modified to turn them into drag racers. >> the airplane looks different. we cut ten feet off the wings, five feet off each side. >> reporter: in a promotional video, jimmy leeward, the pilot who crashed, described the extensive modifications that made this old propeller plane race as fast as a jet. >> you need those types of speeds, you need jet speeds. >> any time you modify an airplane that has been designed for one function, to make it do another function, it makes it less safe. >> reporter: eyewitnesses say they saw pieces of the plane's tail fall off as it made its final turn. the photos support that. and there's this picture, taken the instant before the crash. >> there is no pilot's head in that cockpit. that tells me he was likely unconscious, slumped over the controls. >> reporter: piecing together exactly what happened is now the task of federal investigators. >> really our mission is, eye