On June 24, 1995, at 1230 central daylight time, a Luscombe 8A, N2086K, was substantially damaged while taking off from Edward Getzelman Airport, Hampshire, Illinois. The pilot and passenger reported serious injuries. The local 14 CFR Part 91 flight operated without a flight plan in visual meteorological conditions. The pilot stated that the flight was to be a familiarization flight for the passenger. It was decided that the passenger, who holds an airline transport pilot certificate, was to perform the takeoff. The passenger was seated in the left seat. In a telephone interview with the passenger, he stated that for the takeoff he was "at the controls with guidance." He also stated that he and the pilot had a clear understanding, prior to takeoff, that the pilot was the pilot-in-command (PIC) of the flight. After completing the preflight, the PIC stated he taxied the airplane to the end of runway 36 (2200' x 100') where he performed an engine run-up which he reported was normal. The PIC stated that he then briefed the passenger on the instrument panel, the takeoff, and the abort point on the runway in the event a normal takeoff could not be accomplished. The passenger then began the airplane's takeoff roll on the grass runway. The PIC stated all instrument readings were normal. "The plane became airborne briefly at an expected point but settled back to the runway," the PIC stated. At this point, the passenger pulled the throttle to the idle position and began to apply the brakes to abort the takeoff. The airplane exited the end of the runway, crossed a hay field, and struck a ditch along a cornfield and became inverted. The PIC reported the temperature at the time of the accident was 92 degrees. In a telephone interview, the PIC stated that he had performed a mental calculation of the airplane's weight and balance prior to takeoff. He had determined that the airplane was loaded within limits. The PIC stated that he was not able to compute the airplane's takeoff distance because there are no performance charts available for the airplane. He also stated the engine operated normally throughtout the event.