Shortly after take-off a loud banging noise was heard from the inboard area of the right wing. The pilot elected to fly a low level circuit and land to investigate the noise. On short final approach heavy sink was encountered, and despite the application of power the aircraft touched down about 100 metres short of the runway. It ran through the airport boundary fence and came to rest near the flight strip with the gear collapsed. Investigation revealed that a section of the door seal had become unstuck and had trailed in the slipstream, beating against the door. The pilot had believed that the aircraft had suffered a serious malfunction and was anxious to land as soon as possible. Her husband, who occupied the right front seat, was a more experienced pilot. However, he did not offer to take control of the aircraft. It was probable that the airspeed during the approach was less than the optimum. When sink was encountered, the power and control inputs which were applied were insufficient to prevent the aircraft striking the ground in a semi-stalled condition.