On December 12, 1999, at 1130 Eastern Standard Time, a homebuilt RAF 2000 gyrocopter, N78ME, was substantially damaged from collision with tree stumps and a stone wall during takeoff from a private grass strip in Franklin, New York. The certificated commercial pilot was seriously injured. Visual meteorological conditions prevailed for the personal flight, and no flight plan was filed for the flight conducted under 14 CFR Part 91. In a telephone interview, the pilot stated the purpose of the flight was to do a reconnaissance of the grass strip, land, and perform a takeoff. He said that prior to departing for the strip, he advised a friend of his intentions, and asked the friend to come look for him if he did not return by a specified time. The pilot said he landed on the strip, walked its length, and determined he could complete a safe takeoff. He said he completed one run down the strip and then taxied back for takeoff. He said: "I think I have approximately 70 hours in that model. I had been practicing for about 15 to 20 hours on grass. That was either the first or second unimproved runway that I had used. I landed, walked it, and figured I could make it. The machine did what it was supposed to; I just did it at the wrong time. I did not have adequate rotor rpm to clear the obstacles." Examination of photographs revealed the gyrocopter struck freshly cut tree stumps and a stone wall at the departure end of the strip. According to the pilot: "You apply the pre-rotator [clutch] and at 150 rotor rpm, you start easing on the power, your stick is back, and you start your ground roll. At 200 rpm, you release the pre-rotator and go full throttle." The pilot said that at the end of the ground run, the rotor rpm was approximately 190-195. He said he chose to continue at the lower rpm instead of aborting the takeoff. The pilot said: "It had been flying fine. Why I didn't handle it right, I don't know. I hate to use the phrase, but it was pilot error." The pilot reported approximately 4,700 hours of flight experience, 70 hours of which were in make and model. Weather reported at the time of the accident was clear skies with no wind.