"Felt Like The Tail Was Thumping"

On May 9, 2020, about 0630 central daylight time, an experimental Titan Tornado S airplane, N318WH, was substantially damaged when it was involved in an accident about 3 miles north of Haskell Airport (2K9), Haskell, Oklahoma. The pilot sustained serious injuries. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. According to the pilot, he departed from 2K9 and climbed about 600 feet per minute to 2,000 ft where he intended to level off. He stated that the airplane was flying really well with no anomalies noted at that point. As he decreased the pitch attitude, very suddenly the airplane vibrated aggressively and it "felt like the tail was thumping."