On September 26,2010, approximately 1700 central daylight time, a Beech A36TC, N468SG, registered to and operated by the pilot, was substantially damaged when it struck a barbed wire fence and impacted an open field during takeoff from a grass airstrip 1 mile west of Snook, Texas. Visual meteorological conditions (VMC) prevailed at the time of the accident. The personal flight was being conducted under the provisions of 14 Code of Federal Regulations (CFR) Part 91 without a flight plan. The pilot, the sole occupant on board the airplane, was not injured. The cross-country flight was originating at the time of the accident, and was en route to Austin (3R9), Texas. According to the pilot's accident report, the wind had been out of the north between 5 and 10 knots for most of the afternoon. A cold front had recently passed through the area. He boarded the airplane and, unbeknownst to him, wind velocity increased to about 20 knots. The pilot elected to make a down hill takeoff. The pilot wrote, "About 3/4 way down the strip, I realized the airplane was not light on the controls and was not ready to fly. I noted the IAS was 60 knots and I kept the plane on the ground until reaching the end of the strip. I climbed up and over a barbed wire fence and crossed a deep creek. I then flew up and over a hill, but on the back side of the hill I lost lift and descended slightly. More fences and a road with ditches were coming up, so I climbed again. There was a 6-inch diameter pipe with a phone box mounted on it extending up about five feet above the fence on the near side of the road. The pipe cut off my left tip tank and the outboard portion of my left wing. After crossing the road and ditches, I struck a fence on the far side of the road and settled in a cow pasture. I went through another barbed wire fence and the rough ground in the pasture created side loads on my main gear, causing it to collapse inwards into the wells. The plane stopped and I shut the engine down normally. The nose gear remained extended and the only prop strikes were those on the fence wire." Upon exiting the airplane, the pilot estimated the wind had increased to 25 knots. The pilot said he had flown in and out of the airstrip for forty years without incident. He said the dry, freshly-mowed airstrip dropped 20 feet from the northwest to southeast. He had never installed a windsock because he was familiar with the terrain and varying wind conditions. He hadn't expected "the secondary wind gust that suddenly developed late that afternoon. A windsock is the only way I could have known about the changing wind speed."