On April 14, 2013, about 0900 central daylight time, an experimental Quad City Ultralight Acft Corp Challenger I airplane, N171DP, descended and impacted terrain following a takeoff from the Chambers County-Winnie/Stowell Airport, near Winnie, Texas. The pilot who was the sole occupant sustained serious injuries. The airplane sustained substantial wing damage. The airplane was owned and operated by the pilot under the provisions of 14 Code of Federal Regulations Part 91 as a personal flight. Day visual flight rules (VFR) conditions prevailed for the flight, which did not operate on a VFR flight plan. The local flight was originating at the time of the accident.The pilot had recently purchased the airplane. According to the pilot's accident report, he climbed the airplane and was at 300 to 400 feet above ground level where he leveled the airplane off and reduced its engine power. He stated that he fixated on the instrument panel instead of staying concentrated on flying. The pilot indicated that he did not feel the airplane bank left and he "mashed down on the left aileron pedal too much." The airplane pitched down and started to spin. The pilot pulled on the "stick" and applied "full right aileron." The airplane did not immediately respond to the pilot's control inputs. As the airplane recovered from the spin, the wing made contact with the ground. The pilot reported that there were no mechanical malfunctions with the airplane during the accident flight. He did not have a Federal Aviation Administration pilot's license nor a medical certificate. A witness, who was the prior owner of the accident airplane, observed the pilot and airplane during the takeoff. He saw the pilot "immediately start cross controlling the airplane." The witness thought the control inputs were full left rudder and right aileron. After the airplane climbed between 200 to 300 feet above ground level, the airplane started a left turn. The airplane made a complete 360 degree turn, it pitched down where its wings leveled, and it began making a right turn that tightened and appeared to develop into a spin. The right wing struck the ground first, followed by the nose and the left wing. He indicated that the aircraft came to rest upright. At 0935, the recorded weather at the Beaumont Municipal Airport, near Beaumont, Texas, was: Wind 060 at 3 knots; visibility 10 statute miles; sky condition overcast clouds at 1,100 feet: temperature 20 degrees C; dew point 17 degrees C; altimeter 29.79 inches of mercury.