On August 17, 2004, about 1830 eastern daylight time, an amateur-built Stephen T-bird TBT06, N655DM, piloted by a non-certificated pilot, was substantially damaged when it impacted trees and the ground shortly after takeoff from a private airstrip near Gobles, Michigan. The 14 CFR Part 91 personal flight was operating in visual meteorological conditions without a flight plan. The pilot and passenger received serious injuries. The local flight was originating at the time of the accident. In a telephone conversation, the pilot stated that he performed a pre-flight inspection and warm-up of the airplane prior to the flight. He said that he performed a full-throttle takeoff and cleared a grouping of 70 to 80 foot tall trees by approximately 50 feet. He stated that he was above the stall speed of the airplane the entire flight. He said that after clearing the trees the airplane started descending and would not climb. He said that the airplane continued to descend until impacting more trees even though the airplane was at full throttle. He stated that there were no mechanical difficulties with the airplane. He stated that the weather conditions where the accident occurred were light winds at about 4 knots. He stated that there were some black clouds associated with a thunderstorm to the north of this location.