According to the pilot, he was repositioning the tail-wheeled airplane from a 720-foot grass strip to an airport for maintenance. He computed a takeoff distance of 450 feet and completed two practice takeoff runs to verify that the airplane was able to take off from the short runway. During the practice runs, about 400 feet down the runway, when the airspeed indicated 50 knots, the tail "came up normal" and the pilot aborted the takeoff. About 400 feet into the accident takeoff roll, the airplane encountered a "dip," briefly became airborne, then settled back onto the runway. The pilot continued the takeoff, and rotated the airplane 100 feet prior to a cornfield off the departure end of the runway. The pilot attempted to gain altitude, but the airplane struck corn stalks and descended into terrain, which resulted in substantial damage to the fuselage, wings, and engine firewall. The pilot reported there were no mechanical anomalies with the airplane. The winds reported at an airport 30 miles to the north of the accident location were calm.