On October 14, 2015, about 1445 central daylight time, an experimental amateur-built Zenith STOL CH701, N4931M, was substantially damaged shortly after taking off from Weedon Field (EUF), Eufala, Alabama. The private pilot was not injured. Visual meteorological conditions prevailed, and no flight plan had been filed for the flight to Eu-Wish Airport (MU68), Hermann, Missouri. The personal flight was operating under the provisions of 14 Code of Federal Regulations Part 91.After the accident, the pilot was granted permission by the NTSB investigator in charge to transport the airplane to his home in Missouri, being advised that additional information would be requested. The pilot subsequently failed to respond to any NTSB information requests, either directly or through his attorney. The investigation could thus only rely on the information gathered onsite by the responding Federal Aviation Administration (FAA) inspector, and on a written statement from the pilot subsequently provided through his attorney to the FAA inspector. According to the pilot, he had purchased the airplane the day before in Florida, and was flying it home to Missouri, stopping at EUF to refuel. After refueling, the engine would not start, and the battery discharged. After charging the battery, the engine started "normally." In a written statement the day of the accident, the pilot stated that after takeoff, about 50 feet above the runway, the airplane "turned left and did not respond to any control inputs to trim right and stay over the runway. Instead, it continued a left bank and impacted the ground." In a later statement, the pilot stated that he had performed an engine run-up at 4,000 rpm without noting any anomalies. After which, he taxied to south end of runway 36 and commenced the takeoff. After applying full power, the airplane took longer than normal to take off due to crosswind conditions. About 50 feet above the runway, at mid-field, the engine began to run roughly and vibrate, and was not producing full power. The pilot attempted to "smooth out" the engine by adjusting the throttle; there was no mixture control. The pilot then attempted to land the airplane back on the runway, but in the process, it veered off the left side and flipped upside-down. The pilot egressed the airplane, and reached back in to turn off the fuel valve as the emergency vehicles arrived. According to the responding FAA inspector, the airplane had been moved to a hangar prior to her arrival. There, she noted that one blade of the three-bladed composite propeller was broken off and one was cracked. There was no bending or twisting of the propeller blades. There was no dripping or splattering of oil on the engine cowling. No anomalies were noted within the engine compartment. The fuel bowl on the left side of the engine was full, and both wing fuel tanks were full of fuel. The inspector also drained fuel from each of the two wing tanks, and the fuel sump on the underside of the fuselage, just aft the engine compartment, and all samples were "clear and clean." The inspector noted no control binding to the elevator or rudder, and while checking for aileron binding (none noted), the pilot stated that the controls "got mushy." The FAA inspector subsequently drove out along the runway to where the airplane was recovered, which was about 3,200 feet from the departure end of the 5,000-foot runway. Weather, recorded at the airport 13 minutes after the accident, included clear skies and calm winds.