The pilot reported that after he completed an aerial observation flight, he decided to conduct a simulated engine out approach to an open field. When the airplane was about 40 ft above ground level, the pilot aborted the approach by applying full engine power and elevator backpressure. The pilot stated that the descent was not immediately arrested, but the airplane seemed to be accelerating. As the airplane continued to descend, it slipped to the left and the left main landing gear struck a bush which induced more left yaw and loss of lift. Subsequently the wing struck vegetation and terrain and the airplane cartwheeled before it came to rest upright. The airplane sustained substantial damage to the wings and fuselage. The pilot reported that there were no preaccident mechanical malfunctions or failures with the airplane that would have precluded normal operation.