The unoccupied airplane inadvertently became airborne and crashed shortly after the pilot hand-propped the engine. The pilot reported that he attempted to hand-prop the engine because the aircraft's battery had insufficient charge to utilize the electric starter. The pilot stated that he "tied the tail down" with an automotive style, webbed cargo strap. The pilot reported that after successfully starting the engine, the tail tie-down failed as he repositioned himself to get into the cabin. The pilot stated that he reached "in through the window and tried to pull the mixture out, but could not reach it." The pilot reported that he hung onto the aircraft as it began to accelerate forward, and believes he "moved the throttle more open" before having to let go of the airplane due to its increasing ground speed. The unoccupied airplane eventually became airborne and crashed about one mile from the ramp area. The pilot stated that the accident could have been prevented if he had used wheel chocks, utilized another tie-down on the tail, or had a person at the aircraft's controls during the hand-start.