On October 29, 2010, approximately 1430 central daylight time, a Walker Sonex airplane, N234KS, impacted terrain near San Angelo, Texas. The private pilot and student pilot were seriously injured. The airplane sustained substantial crushing damage to the wings and fuselage. The airplane was registered to and operated by a private individual under the provisions of 14 Code of Federal Regulations Part 91 as a personal flight. Visual meteorological conditions prevailed for the flight, which operated without a flight plan. The flight was originating from a private airstrip at the time of the accident. According to a statement provided by the student pilot, the flight was the second flight the two pilots had flown that day. The private pilot was controlling the airplane during the accident flight. At an estimated 100 feet above ground level the student pilot heard a loud noise come from the back of the airplane like they had struck an object. The airplane began to vibrate and the private pilot told the student pilot that he did not have control of the airplane. The student pilot recalled that the engine appeared to be operating at full power with his last recollection that the airplane in a left turn with a nose high attitude before impacting terrain. An inspection of the airframe and engine by a responding Federal Aviation Administration inspector did not reveal any preimpact anomalies which would have precluded normal operation of the aircraft. Impact signatures were consistence with an aircraft stall during the initial climb. There was no evidence of a material failure to explain the loud noise prior to the accident; the source of the loud noise was not determined. A blood sample obtained from the private pilot by the Texas Department of Public Safety (DPS) revealed an intoxication level of 0.11 blood alcohol content.