The pilot reported that during the initial climb the airplane reached 300 ft agl and then began to sink. He made a shallow turn, committed to landing in a field, and then began shutting down the engine, fuel, and electrical systems. During landing in the rough field the landing gear collapsed and the airplane sustained substantial damage to the right wing, fuselage, and engine mount. The pilot reported that there were no preaccident mechanical malfunctions or failures with the airplane that would have precluded normal operation. Based on information provided by the pilot, the airplane was roughly 100 lbs over the maximum allowable gross weight. The meteorological data for the date and time of the accident was used to calculate an estimated density altitude of 6,473 ft. Surface conditions showed a 20 knot direct headwind gusting to 30 knots for the runway being used and an outside air temperature of 29° Celsius. The performance chart for the airplane at maximum gross weight for these conditions showed a climb performance of about 400 feet per minute (fpm). It is likely that the airplane, which was overweight and operating at a high-density altitude, had a lower climb performance.