During an early-morning flight, an experimental Wallace Skybolt broke up while executing an aerobatic maneuver near Reno/Stead Airport. The private pilot, the sole occupant, sustained serious injuries; the airplane was destroyed. The pilot reported that he was executing an outside loop. At the bottom of the loop, while inverted at about 8,000 feet msl, the pilot felt a vibration for 1 to 2 seconds. Subsequently, the right wing departed the airplane. As the airplane disintegrated, the pilot was able to release his seat belt and exit the airplane, deploying his parachute just before impacting the ground.