The accident occurred during the second flight since manufacture/certification. The experimental amateur built airplane was a reproduction of a WWI British fighter that was in production 1916-1918. On the first flight, the pilot noted that forward stick pressure was needed to maintain level flight. The pilot/builder subsequently adjusted the horizontal stabilizer to increase the nose-down flight characteristics. On the second flight, the pilot stated that the takeoff was normal but the airplane had a lower rate-of-climb and airspeed than the first flight. Upon reaching 2,000 feet, the pilot reduced engine power and noted having normal stick pressure to maintain a level flight attitude, but a 10 mph drop in airspeed and 100 feet per minute descent rate. The airspeed and altitude continued to decrease as he turned to the left. An increase in engine power did not result in an increase in airspeed or reduction of the descent rate. The pilot stated that the airplane continued to loose airspeed and altitude until about 30-40 feet about ground level when the right wing dropped and the airplane impacted terrain. The original airplane design incorporated an engine installation with a zero degree engine thrust angle. The accident airplane incorporated a different engine that resulted in a -12 degree engine thrust angle. The pilot/builder was unaware of the thrust angle differences until after the accident flight.