The 71 hour student pilot reported that while maneuvering his experimental homebuilt airplane, 'the aircraft entered a slow right hand, uncontrolled turn, [and] continued [in] that mode of flight until impacting the earth.' A witness reported observing the airplane's nose drop as it made a right turn. Subsequently, the airplane's right wing and nose impacted the ground. The witness further reported that the engine was running during the entire event. According to the FAA inspector, high gusty wind conditions prevailed at the time of the accident.