On May 6, 1998, about 1800 eastern daylight time, a Piper PA-22-150, N3900P, registered to Air Group Inc., crashed during takeoff at a private airstrip, near Woodstock, Georgia, while on a Title 14 CFR Part 91 pleasure flight. Visual meteorological conditions prevailed at the time and no flight plan was filed. The airplane was substantially damaged. The airline transport-rated certified flight instructor and private-rated pilot/passenger were not injured. The flight originated from Marietta, Georgia, at 1700. According to the pilot-in-command (PIC), after a local flight of about 1 hour, the two pilots decided to "check-out" a grass strip that they had flown over. The grass runway was oriented north/south and they landed on runway 18. On approach, they noted that the runway was "uphill." After landing, they noted that the wind socks indicated that the ground winds were "calm." They elected to depart on runway 36, and the PIC initiated a "short" field takeoff. They crossed a road at the north end of the field, and the PIC stated, "...but [the airplane] did not clear the trees." He said, "...we clipped the top of the first tree and the prop went through the second...we caught a larger tree on the inboard right wing." The reported winds at Dobbins Airbase, Georgia, located about 10 miles north of the crash site were from 150 degrees at 9 knots.