On July 28, 2013, about 1230 central daylight time, a kit built Vans RV-8A airplane, N131RP, impacted terrain near Lucas, Kansas. The non-instrument rated private pilot was fatally injured and the airplane was destroyed. The airplane was registered to and operated by a private individual under the provisions of 14 Code of Federal Regulations Part 91 as a personal flight. Instrument meteorological conditions prevailed for the flight, which operated without a flight plan. The flight originated from Larned, Kansas, en route for Atlantic, Iowa. According to statements collected by the responding Federal Aviation Administration (FAA) inspectors, the accident airplane was flying in a trail formation from another airplane. The accident pilot was trailing the lead airplane while they maneuvered between cloud layers about 7,500 feet mean sea level. As the formation approached Lucas, Kansas, the accident pilot requested the heading of the lead airplane. The lead airplane's pilot reported his heading and saw the accident airplane about 1 mile behind him about 800 feet below his altitude. There were clouds about 1,000 feet below and 4,000-5,000 feet above the lead airplane and visibility was estimated between 4-5 miles. The accident pilot reported that he could not see the lead airplane. Shortly thereafter, the accident pilot again requested the lead airplane's heading. The lead airplane's pilot again reported his altitude, but could not visually locate the accident airplane. There were no further radio transmissions from the accident pilot. An eyewitness was repairing a fence in a pasture about ¾-mile north of the accident site. He stated that the weather at the time of the accident was rain showers and a cloud ceiling about 50 feet. He heard what sounded like one or two airplanes circling overhead. He heard the impact and could still another airplane flying overhead. He commented that the accident airplane's engine sounded at high rpm until the impact. The airplane's wreckage was located in a field by a local resident. On scene documentation conducted by the FAA inspectors revealed that airplane was highly fragmented over a relatively large area. The debris field ran from the southwest to the northeast. Ground scars and damage to the airplane was consistent with the airplane in a 60 degrees left turn. The pilot held a private pilot certificate for airplane single engine land. There was no record of the pilot holding an instrument rating. The pilot's last medical certificate was a third class certificate issued on December 3, 2001. The certificate was not valid for any class after December 31, 2003. On the medical application the pilot reported accumulating 400 total hours with no flight time in the preceding six months. However, acquaintances of the pilot estimated that the pilot had 300-400 hours in an RV-6 and 130-150 hours in an RV-8. On the 2001 medical application, the pilot reported being prescribed several medications and was being treated for coronary artery disease. The status of the pilot's coronal artery disease could not be determined. However, several people who interacted with the pilot prior to the accident flight did not detect any unusual behavior or medical conditions with the pilot. Forensic toxicology was performed on limited specimens from the pilot by the FAA Bioaeronautical Sciences Research Laboratory, Oklahoma City, Oklahoma. Testing discovered the presence of carbamazepine and ranitidine. Carbamazepine is an anticonvulsant. Used for treatment of seizure disorders, bipolar disorder, trigeminal neuralgia and off-label for a variety of pain disorders and mental conditions. Ranitidine is a histamine H2-receptor antagonist. It is used to decrease gastric acid production and treat ulcers, and a number of other stomach complaints. Neither medication had been previous reported to the FAA. At 1253, an automated weather reporting facility located 14 nautical miles southwest of the accident site reported wind from 110 degrees at 12 knots, visibility 10 miles, an overcast ceiling at 400 feet, temperature 63 degrees Fahrenheit (F), dew point 61 degrees F, and a barometric pressure of 30.02 inches of mercury.