During the takeoff roll the pilot noted a loss of aircraft performance, but considered that there was insufficient strip length remaining to safely stop the aircraft. Shortly after becoming airborne the tail assembly struck the wooden top railing of a bridge. The left wing tip struck a dead tree 65 metres further on, the aircraft slewed to the left, touched down and came to rest with the engine and landing gear torn from the fuselage. No fault could be found with the aircraft systems which may have contributed to the reported loss of performance. The take-off, on a oneway strip, was conducted with a slight tailwind component and the estimated take-off weight slightly exceeded the climb weight limit specified in the aircraft P chart. The pilot's technique to assist in getting the aircraft airborne was to progressively select full flap during take-off. On this occasion the use of full flap apparently degraded the climb performance of the aircraft to such an extent that it collided with the bridge.