The 287-hour private pilot reported that the homebuilt airplane experienced a loss of engine power during initial takeoff climb. The airplane impacted the ground while the pilot attempted to return to the airport. The airplane impacted the ground in a nose low attitude and came to rest in the upright position in an open field within 50 yards of the runway. The Federal Aviation Administration inspector, who responded to the accident site, was able to interview the pilot at the scene of the accident. The pilot reported that the airport perimeter fence limited the possibility of proceeding straight ahead for a forced landing. The pilot added that a turn was needed to maneuver the airplane to a suitable landing area. The inspector documented structural damage to all portions of the airplane forward of the cockpit, confirmed the availability of full fuel on board, and did not note any obvious discrepancies. In a telephone interview with the NTSB Investigator-in-Charge (IIC), the pilot stated that during the emergency turn back to the airport, he allowed the airplane to slow below minimum flying speed and, due to close proximity to the ground, was not able to successfully recover the aircraft prior to impacting the terrain. The pilot, who was also the builder of the airplane, was not able to determine the reason for the engine's occasional loss of power. The pilot, who was also a mechanic, performed an inspection on the engine and could find a reason for the loss of engine power. The pilot added that he thought the engine malfunction was the result of a carburetor related problem. The airframe and engine had accumulated a total of 175 hours. An automated weather reported station at the Lubbock Preston Smith Airport (KLBB), 32 nautical miles south-east of the accident site, reported at 1253 winds from 060 degrees at 3 knots, visibility 10 statute miles, scattered clouds at 5,000 feet, temperature 83 degrees Fahrenheit, dew point 57 degrees Fahrenheit, and barometric pressure of 30.12 inches of Mercury.