On July 22, 2014, about 2055 eastern daylight time, an experimental light sport Ultrastar, N4425W, was substantially damaged during a forced landing just after takeoff from a private airstrip near Halifax, Pennsylvania. The student pilot was seriously injured. Visual meteorological conditions prevailed, and no flight plan was filed for the local personal flight, which was conducted under the provisions of Title 14 Code of Federal Regulations (CFR) Part 91.According to the pilot, he had not flown the airplane in about three years, and in the days preceding the accident flight, had been inspecting the airplane. The inspection included removing the carburetor float bowls to check for contamination, performing run-up checks of the engine, and performing several high-speed taxi runs down the length of the runway. Noting no abnormalities, he ultimately elected to depart on the accident flight. During the initial climb after takeoff, while about 200 feet above the ground, the pilot noted that the airplane's engine did not seem to be producing enough power. He elaborated that the engine continued to sound normal, but he felt as if its power output was slowly decreasing over the course of about 10 seconds. Due to the small size of the tachometer, he was unable to determine if the engine rpm had changed. With the airplane descending, the pilot chose a cornfield as a forced landing site, as there was no safe area straight ahead, nor did he feel the airplane had enough altitude to return to the runway. During the approach for landing, the airplane slowed, entered an aerodynamic stall, and impacted the cornfield, resulting in serious injury to the pilot and substantial damage to the airplane. Following the accident, the wreckage was not recovered nor was it examined. The airplane was originally manufactured in 1991, and was equipped with a Cuyuna 430 two-stroke engine. The airplane was issued an airworthiness certificate on December 12, 2009, as an existing aircraft without an airworthiness certificate that did not met the requirements of CFR Part 103.1. At the time the airworthiness certificate was issued, it had accumulated 142 total hours of operation. The single-seat airplane was equipped with a 5-gallon fuel tank, had an empty weight of 349 pounds, and a maximum gross weight of 650 pounds. The pilot held a student pilot certificate, which was issued on October 2012, and an FAA third-class medical certificate, which was issued in January 1999. He also held a repairman certificate with a light sport aircraft inspection rating for the accident airplane. Airman records maintained by the FAA did not contain a total number of flight hours by the pilot, and no flight experience or student pilot certificate endorsement records were made available by the pilot for inspection. The weather conditions reported at Muir Army Airfield, Annville, Pennsylvania, located 16 nautical miles east of the accident site, at 2058, included wind from 200 degrees true at 5 knots, few clouds at 5,000 feet, a temperature of 27 degrees C, a dew point of 22 degrees C, and a barometric altimeter setting of 30.08 inches of mercury. According to the U.S. Naval Observatory, sunset occurred at 2032 and the end of civil twilight occurred at 2103. The moon set at 1708 and did not rise again until 0314 the following day.