The pilot performed a wheel landing in a tailwheel-equipped airplane with variable wind conditions present. During the landing roll, the tail of the airplane began to settle as the airplane veered suddenly to the right. The pilot's efforts to correct the veer were unsuccessful and the airplane ground looped. Examination of the airplane revealed that the left main landing gear was underneath the fuselage and the outboard portion of the left wing was structurally damaged. The pilot stated there was no mechanical anomalies with the engine or flight control system at the time of the accident.