The airplane was substantially damaged at approximately 1725 Mountain time when it impacted terrain off the departure end of the runway. Visual conditions prevailed; the Private pilot sustained minor injuries. Several witnesses reported that, during the takeoff roll, the airplane appeared to take off, settle back to the runway and then take off again. One witness stated that the pilot appeared to abort the takeoff. The aircraft departed the end of the runway, rolled down the embankment and nosed over, coming to rest 1287 feet from the departure end of the runway.