[QUOTE=olnico;12258473]I don't think it is rudder flutter.
The pilot comes in at full power for a knife edge pass. Kicks the rudder in full travel.
The fin separates due to excessive aerodynamic loads. /QUOTE]
Same thing happened to the full size BD-10:
https://en.wikipedia.org/wiki/Bede_BD-10
Fox's first prototype, N9WZ, was completed in 1994 and entered testing. Although it had been modified to incorporate the stronger tail of Bede's design, it broke up mid-air on 30 December 1994 when the vertical stabilizers failed due to a crossflow condition, killing Van Wagenen. The National Transportation Safety Board (NTSB) later concluded that Bede's fix was severely under-designed, and offered nowhere near the strength that had been calculated.[SUP][7][/SUP] Fox had not performed any testing to verify the redesign of the vertical stabilizer spars before continuing flight testing, instead relying upon the data provided by Bede.