On August 21, 2005 about 1130 eastern daylight time, an experimental amateur-built Yamokoski Glastar airplane, N4970Y, sustained substantial damage when the airplane nosed over on impact with high vegetation and terrain during a forced landing following an in-flight loss of engine power near Marcellus, Michigan. The personal flight was operating under 14 Code of Federal Regulations Part 91. Visual meteorological conditions prevailed at the time of the accident. No flight plan was on file. The pilot reported no injuries. The flight originated from the La Porte Municipal Airport, near La Porte, Indiana, about 1100 and was en route to the Mason Jewett Field Airport, Mason, Michigan, at the time of the engine power loss. The pilot's accident report, in part, stated: Noted slight [decrease] in rpm. A minute later, engine began occasional misfire. Engine continued to lose power/rpm, ran increasingly rough until it quit another minute later. At first sign of [decreased] power, turned in direction of nearest airport. Altitude was about [2,800 feet]. Ran fuel selector through all positions; no improvement noted. Determined nearest airport unreachable. Found empty field and directed airplane toward it. Landed short in field [with] tall corn. Aircraft slowed, nose dug in, flipped forward onto its back. A Federal Aviation Administration inspector examined the wreckage. The examination did not reveal any pre-impact anomalies.