The 4,319-hour airline transport rated pilot completed the third leg of his flight and was landing at an intermediate stop to refuel the 1941-vintage biplane. The pilot reported that he executed a normal approach for landing on runway 04 (a dry asphalt 5,659-foot long by 75-foot wide runway) with the winds being reported from 050 degrees at 5 knots. During the landing flare for a three-point landing, the pilot reported that the nose of the airplane began to veer to the right and roll to the left. The pilot attempted to correct for the drift when the airplane exited the right side of the runway and ground looped. During the ground loop, the fabric-covered left wing impacted the ground resulting in structural damage to the left wing strut. The pilot, who was uninjured, reported having accumulated a total of 11-hours in the make and model.