On April 7, 2003, about 1816 eastern daylight time, an experimental airplane built by Ghiles Philippe/American Ghiles Aircraft, Inc., N6370X, registered to American Ghiles Aircraft, Inc., collided with terrain during takeoff from the Lakeland Linder Regional Airport, Lakeland, Florida. Visual meteorological conditions prevailed at the time and no flight plan was filed for the 14 CFR Part 91 personal flight. The airplane was substantially damaged and the commercial-rated pilot was not injured while the pilot-rated passenger sustained minor injuries. The flight was originating at the time of the accident. The pilot stated that the day before the accident date he walked the entire length of the grass runway and questioned a EAA officer about the length of the runway, confirming that it was 1,500-feet long. The day of the accident the pilot obtained a preflight weather briefing, added 3 gallons of 100 low lead fuel to the main fuel tank which brought the amount of fuel in the 21-gallon tank to approximately 75 percent capacity or 15 gallons. He also performed weight and balance calculations which indicated that at the time of takeoff, the airplane was approximately 50 pounds under maximum gross weight. He estimated the takeoff roll to be 715 feet based on the temperature, and airplane weight at the time of takeoff; he added 20 percent to the calculated distance for the grass runway. He performed a preflight inspection of the airplane two times using the checklist; one time was in the presence of the passenger; no fuel contamination was noted. The passenger boarded the airplane and was briefed on the emergency procedures; the passenger also received help donning his seat restraint consisting of a lap belt and shoulder harness. He set elevator trim using the width of his hand as reference for clearance between the stick and the instrument panel. After engine start and before takeoff, he performed an engine run-up; no discrepancies were noted; the adjustable propeller was set to 22.5 degrees blade angle. The pilot further stated he elected to perform a combination short and soft field takeoff with the flaps extended between the first and second notches. After being cleared to takeoff by the marshaller, he applied the brakes and increased power to 75 percent, then checked the engine gauges. He then released the brakes and applied full power noting the tachometer indicated 5,600 rpm (yellow arc). He reported the airplane accelerated "well" during the takeoff roll, and he began to rotate at 60 knots. At a point during the takeoff roll he wasn't sure the airplane would become airborne, but at that point there wasn't enough runway ahead to stop so he elected to continue the takeoff. He attempted to keep the wings level and the airplane, "...came out of ground effect, and the airplane sank to the ground...." The airplane came to rest on its right side, and he assisted in unbuckling the passenger who was helped from the airplane by bystanders. He further stated that he did not perceive of an engine or propeller malfunction, but he wasn't feeling lift. Witnesses reported that the pilot positioned the airplane to have all runway available for takeoff. The engine was heard to accelerate to what one witness thought was full power while the brakes were applied. The airplane was observed to start the takeoff roll during which time several witnesses reported seeing the airplane in a nose high attitude and the bottom portion of the empennage contacting the runway at least one time. The airplane was observed becoming airborne after the end of the runway only because of a lower elevation, then impacted terrain while in a tail low attitude. The airplane then nosed over and came to rest inverted. No unusual sounds were reported from the engine during the takeoff roll. One witness reported that the wind shifted during the takeoff and when the airplane was 1/2 way down the runway, the wind was from the southeast at 4-5 knots; the wind had been favoring departures from runway 27. Examination of the accident site revealed the airplane impacted terrain approximately 101.4 feet past the departure end of the runway, and came to rest inverted approximately 97.4 feet from the initial impact point. The elevation of the impact point was approximately 10-15 feet lower than the runway elevation. Examination of the airplane following recovery by the NTSB revealed flight control continuity for roll, pitch, and yaw. The fuel selector valve was found in the "on" position, and calculations indicate that 14.7 gallons of 100 low lead fuel were drained from the fuselage tank; no contaminants were noted. Examination of the tail fairing revealed evidence of being scraped and ground down. Grass debris was noted inside the fairing. Examination of the cockpit revealed the propeller control was set to "Auto" and "21." The flaps were examined post accident and found to be retracted. Examination of the runway which was later determined to be 1,423 feet in length revealed no determination could be made as to where the empennage contacted the runway surface. Examination of the engine revealed suction and compression from all cylinders. The left carburetor bowl contained 100 low lead fuel, while the right carburetor bowl contained only residual 100 low lead fuel. All 3 propeller blades were shattered near the hub. No evidence of preimpact failure or malfunction of the engine was noted. Examination of the propeller revealed that all 3 propeller blades were estimated to be between 20 and 25 degrees; low blade angle is set to 13.5 degrees plus or minus 0.2 degree.