THE PLT OF THE RUSSIAN BUILT ACFT WAS PARTICIPATING IN AN AEROBATIC SHOW, OF WHICH, HE WAS THE DIRECTOR. HE HAD RPRTD HE WAS FATIGUED, THAT HE HAD BEEN UNDER CONSIDERABLE PRESSURE & THAT HE MIGHT HAVE TO STOP FLYING IN THE AIRSHOW. DRG THE AIRSHOW, A VERTICAL TORQUE ROLL & TAIL SLIDE WERE PERFORMED. ANOTHER TORQUE ROLL & TAIL SLID WERE THEN MADE THAT RESULTED IN AN INVERTED RECOVERY. FINALLY, ANOTHER TORQUE ROLL & TAIL SLIDE WERE PERFORMED THAT EVOLVED IN A 1-1/2 TURN SPIN. SUBSEQUENTLY, THE ACFT INPACTED THE GND IN ABOUT A 65 DEG DSCNT. NO PREIMPACT PART FAILURE OR MALFUNCTION WAS FND THAT WOULD HAVE RESULTED IN THE ACDNT. THE PLT HAD ENGAGED THE SMOKE GENERATOR FOR THE LAST MNVR & SMOKE ENGULFED THE ACFT AS THE TAIL SLIDE BGN. THERE WAS EVIDENCE THE PLT WAS OPERG THE ELEVATOR CTL TO RECOVER BEFORE IMPACT. HE HAD BEEN TAKING A BETA BLOCKER (PROPRANOLOL), WHICH HAD BEEN PRESCRIBED WITH THE WARNING OF NOT TO USE BEFORE FLT. A BLOOD TEST SHOWED 0.15 MCG/ML OF PROPRANOLOL, BUT NO PHYSICAL IMPAIRMENT WAS VERIFIED. DENSITY ALT WAS ABOUT 3800 FT.