On July 29, 2012, at 1343 eastern daylight time, an experimental Smith Applebay Zuni II glider, N1ZV, sustained substantial damage when it impacted trees and terrain while on the downwind leg to runway 36 at the Richmond Field Airport (69G), Gregory, Michigan. The pilot, the sole occupant, received serious injuries. The glider was registered to and operated by the pilot under the provisions of the 14 Code of Federal Regulations Part 91 as a personal flight. Visual meteorological conditions prevailed at the time of the accident. No flight plan was filed for the local flight which originated from 69G at 1329. The pilot reported that he completed the pre-takeoff checklist, which included a positive control check of the flight controls. He reported that the takeoff and tow to 3,000 feet above ground level (agl) was normal. The pilot released the glider from the tow airplane at 3,000 feet agl about 2 miles northwest of 69G. The pilot was unable to find the necessary lift, and as the glider lost altitude, he started flying back toward the airport. Still not finding the needed lift, he proceeded toward the initial point for landing on runway 36. As the pilot flew the downwind pattern leg, he realized that he was not going to be able to complete the pattern. He attempted to clear the tree line that crossed the downwind leg, but the glider hit the trees and subsequently impacted the terrain. A witness located at the airport reported that he observed the glider on the downwind leg. He reported that the glider's altitude was low – about 125 to 150 feet agl, and it was in close to the airport and flying "somewhat slowly." The glider seemed to slow down even more as it began to turn to the base leg. He reported that the left wing stalled and the glider pitched down nearly vertical. It completed about 1/2 spin before it disappeared behind the trees about 2,000 feet away. Another witness at the airport also reported that the glider was too low on the downwind leg. He reported that the glider went down as it turned to shorten the pattern. A Federal Aviation Administration inspector examined the glider wreckage. Flight control cable continuity was confirmed from the flight controls to their respective attach points on the flight control surfaces. The inspection of the glider did not reveal any evidence of pre-impact failure or malfunction.