All the above is conjecture. Facts:1. 2nd year race pilot, non military. 2. he was in the lead 3. aggressive pass by #2 without voice call on race radio. Conjecture: High speed departure due to possible wake turbulence causing over G and G-loss of consciousness followed quickly by descent to the ground with unconscious pilot. If you weren’t there and/or don’t like air races you might not wish to comment.