The pilot reported that all airplane systems were operating normally during his preflight inspection and attempted takeoff. The pilot stated that because of the rocky runway condition, he made a combination soft and short field takeoff with the wing flaps extended to the 20-degree position. The runway was 3,200 feet long by 70 feet wide, and the wind was calm. The pilot stated to the National Transportation Safety Board investigator that full engine power was produced during the takeoff roll, and that initially the airplane rolled straight down the runway's centerline. He also reported that it was his standard procedure to "pull the plane off the ground" upon accelerating to 55 mph. Thereafter, he relaxes the back pressure on the yoke to accelerate to 90 mph, and then he begins climbing. The pilot reported that, during the accident flight, "immediately after I felt the nose come up the plane started tracking left toward the left side of the runway." Although he attempted to maintain directional control, the airplane veered left, and a wing broke upon impacting a juniper tree and terrain.