According to the pilot of the tailwheel-equipped airplane, prior to the takeoff roll he applied one notch of flaps and added power. He reported that just before rotation the airplane veered to the left and he could not keep the airplane on the runway. He reported that he aborted the takeoff, applied the brakes and the airplane exited the runway to the left and impacted a drainage culvert. The airplane sustained substantial damage to the left wing spar and ribs. The pilot reported that there were no mechanical malfunctions or anomalies with any portion of the airplane during the preflight that would have prevented the normal flight operations. The meteorological aerodrome report at the accident airport reported that the wind was out of 100 degrees true at 04 knots at the time of the accident. The pilot departed runway 25.