Pilot Reported That He Filled His Fuel Tanks To Full, For The First Time Since Purchasing The Airplane Analysis: The pilot reported that he filled his fuel tanks to full, for the first time since purchasing the airplane, to conduct a flight test to calculate fuel burn rate. A weight and balance calculation provided by the pilot showed that the airplane was over the maximum gross weight by about 25 lbs. During takeoff initial climb, he observed that the airplane was not climbing as he expected and realized he would not be able to clear the trees or powerlines ahead of his position. The pilot initiated a forced landing to a grass covered field, however, during the approach, he observed that the landing distance available was too short and landed with a side slip to arrest the airplane’s forward movement.