On February 2, 1997, at 1030 eastern standard time, a homebuilt, Vans RV-4, N42BN, was substantially damaged when it struck the ground during a go-around at the York Airport (THV), York, Pennsylvania. The certificated commercial pilot and passenger were not injured. Visual meteorological conditions prevailed for the personal flight that originated at Westminster, Maryland, about 1000. No flight plan had been filed for the flight conducted under 14 CFR Part 91. In the pilot's written statement, he said that he entered the down wind traffic pattern for landing on runway 34, and observed an airplane on the taxiway, short of the runway. When the pilot turned his airplane from base to final approach, the airplane on the ground taxied onto the runway. He elected to do "S" turns to give the airplane on the runway time to depart, but airplane remained on the runway. The pilot also said: "...Prior to ground impact, I elected to wave off...power was applied...Upon rolling wings level...I felt a left slip and stick shaker...The aircraft began falling, rolling left impacting the ground..." The pilot further stated that during ground impact, full power was applied, and the airplane became airborne. The pilot continued the climb and then completed a successful landing at THV. The pilot stated that he encountered no malfunctions with the airframe or engine.