The pilot reported that during takeoff initial climb from the uncontrolled airport, at 50 feet above ground level, he heard the sound of an airplane coming towards him from the left and saw a shadow of the airplane on the ground merging with his, and initiated an abrupt turn of 90 degrees to the right to avoid a collision. Upon completion of the turn, the pilot noticed that he had lost a significant amount of airspeed and was heading toward a residential structure. The pilot initiated a second turn to the right to miss the house and attempted to regain airspeed. Subsequently, the gyroplane impacted terrain adjacent to the runway. The pilot reported no mechanical anomalies with the flight control system or engine prior to the accident. A witness located adjacent to the accident site reported that another aircraft was apparently making a high-speed pass over the runway and overflew the gyroplane as it was taking off.