The pilot reported that he remembered only portions of the accident sequence due to injuries sustained in the accident. He said that during takeoff from a remote, grass-covered site, as the airplane accelerated, he recalled discovering that there was no elevator control when he moved the control yoke aft. The next thing he remembered was being upside-down in the airplane immediately after the accident. The airplane subsequently impacted terrain, sustaining substantial damage to the fuselage, wings, and vertical stabilizer. After the accident, a camp helper told the pilot that due to windy conditions the prior evening, he had placed a large screw through the hole in the control yoke column, but he had forgotten to tell him. The pilot reported no preimpact mechanical malfunctions or failures with the airplane that would have precluded normal operation.