On April 1, 1993, at about 1330 eastern standard time, a Grob 102, N792G, collided with the ground during a forced landing at Kingston, Georgia. The glider was registered to and operated by Atlanta Soaring Club, Inc. under 14 CFR Part 91, and visual flight rules. Visual meteorological conditions prevailed. A flight plan was not filed for the personal flight. There were minor injuries to the private pilot, while the glider was substantially damaged. The flight was originating at the time. During a towed take off, the tow plane's engine lost power. The tow pilot released the glider at about 150 feet above the ground. The glider pilot stated that he released the tow rope, then turned left to provide room to make a right turn back to the runway. According to the glider pilot, during the right turn the "nose fell & I hit the ground." The tow pilot's diagram of the airstrip depicted an open field to the east of the runway. He stated that it was his planned emergency landing site when the engine lost power. Subsequently, the tow pilot discovered that the fuel shut-off valve had been partially closed. The position of the fuel shut- off valve resulted in a loss of power until the throttle was reduced.