The aircraft collided with the ground in a past vertical inverted position. The wings failed in negative load after the pilot lost control in pitch with the airspeed decreasing and stalled into a dive. The pilot was on his first solo flight and his instructor was watching from the ground and talking to him on a one-way radio. The CFI was calling for a level flight at 40-45 mph. The aircraft stalls at 21 mph and has a top speed of 65 mph. The vehicle was about 600 ft AGL when the accident sequence began. The student pilot had flown 10 hours of dual and this solo flight lasted about 25 minutes. Weather was not a factor and no evidence was found of any failures or malfunctions which might have contributed to the accident. The autopsy examination did not disclose any pre-existing conditions which would have detracted from the pilot's ability to fly the vehicle. The pilot was 60 years old and did not have a pilot's certificate.