On February 21, 1998, at 1113 eastern standard time, a Tankersley Europa Mono-wheel homebuilt, N6173K, collided with the ground shortly after takeoff at the Fernandina Beach Municipal Airport in Fernandina Beach, Florida. The airplane was operated by the private pilot under the provisions of Title14 CFR Part 91, and visual flight rules. Visual meteorological conditions prevailed and no flight plan was filed for the local flight. The pilot received serious injuries and the airplane sustained substantial damage. The flight was originating at the time of the accident. According to the pilot, he purchased an engine for the airplane on February 29, 1996. After numerous problems with the engine and no support from the engine dealer, the pilot/builder began to install components that were recommended by others. After installing an oil cooler and exchanging the radiator, the pilot attempted to fly the airplane in order to evaluate the performance. After departing the airport, the airplane was "sluggish." The pilot stated the engine was not producing enough power to climb over the trees. While climbing, the pilot stalled the airplane at a height of approximately 150 feet above the ground. A witness stated, according to an FAA inspector, the airplane had to be restarted several times during taxi to runway 8. The witness also stated that the airplane departed runway 08 and porpoised during the climb. The airplane climbed to about 200 feet above ground level (AGL). He said the airplane then turned left 70 degrees and crashed into runway 4. The witness stated the engine thrust was decreasing. According to the FAA inspector, the engine contained adequate oil, showed no signs of seizing, and was able to be rotated. The fuel tanks contained fuel. The propeller blades showed rotational signatures and damage. He stated that the airplane experienced a partial loss of engine power. The pilot then stalled the airplane and nosed down into runway 4 at a 30 degree angle. The inspector also stated the pilot had plenty of runway ahead of him as well as a grassy area available for landing.