On June 2, 2001, at 1710 eastern daylight time, an experimental certificated Stampe Et Renard SV-4, N25SV, was substantially damaged during takeoff at the Old Rhinebeck Aerodrome (NY94), Rhinebeck, New York. The certificated commercial pilot sustained minor injuries and the passenger sustained serious injuries. Visual meteorological conditions prevailed and no flight plan was filed for the personal flight conducted under 14 CFR Part 91. The pilot stated that he flew into NY94 to visit a friend, who owned the accident airplane. While at the airport, the pilot accepted an offer to fly the airplane in the local area. The pilot performed an extensive preflight inspection with the owner, who briefed him on the airplane's flying characteristics. As the pilot prepared for takeoff, he noted the wind sock indicated variable winds from the south to the west at 10-15 knots. He then taxied to the south runway, and performed a run-up inspection. During takeoff, the pilot rotated the airplane about 400 feet down the runway, and established a climb at "Vy". The pilot stated that the airplane performed "normally" during the takeoff and initial climb. However, about half way down the length of the runway, the airplane "started losing a positive rate of climb," and began to descend. When the pilot realized the airplane would not clear trees at the departure end of the runway, he reduced power and lowered the nose of the airplane to perform a forced landing. The airplane impacted the ground "hard" in a 20 degree nose down attitude, near the end of the runway. The airplane owner witnessed the accident, and stated that the airplane was "running fine" during taxi, takeoff, and initial climb. As the airplane approached trees at the end of the runway, the owner turned his attention away from it. He was drawn back to the airplane when he heard a reduction in power. He then observed the nose of the airplane drop, and impact the runway. The owner reported that he flew the airplane two times on the day of the accident, and that there were no mechanical deficiencies. Examination of the airplane by a Federal Aviation Administration (FAA) inspector, revealed substantial damage to the engine and forward cockpit area of the airplane. No mechanical malfunctions were observed. The pilot reported 11,500 hours of total flight experience, with no previous experience in the accident airplane. He also reported no mechanical malfunctions with the airplane. The runway at NY94 was a 2,200-foot long, and 75-foot wide dirt strip. Weather reported at the Dutchess County Airport (POU), Poughkeepsie, New York, 18 miles away, at 1653 was reported as winds variable at 3 knots, visibility 10 miles, broken clouds at 2,000 feet, temperature 70 degrees Fahrenheit, dew point 63 degrees Fahrenheit, and altimeter setting 29.65 in Hg.