The pilot stated that he departed the airport on a local flight in an experimental amateur built category airplane. After reaching about 100 feet above ground level and about 0.5 nautical miles from the departure end of the runway, the engine "sputtered" and subsequently lost power. The pilot attempted a forced landing to a field located directly in front of the airplane. During the landing, the airplane impacted the ground, the main landing gear splayed, and the airplane skidded about 40 feet before coming to rest nose down in a ditch. The airplane sustained substantial damage to the wings. The pilot reported no preexisting mechanical failures or anomalies, but during a postaccident examination of the airplane he discovered that he had failed to open the fuel tank valves prior to the flight.