Fourth VictimClaimed SundayAt TawakoniA United States Air Force man visiting his Dallas parents while on a furlough from a Phoenix, Arizona, base, became the fourth drowning victim at Lake Tawakoni Sunday about 10:30 a.m.According to Audie Stephens, security officer f r the Sabine River Authority at the lake, the man was Clyde W. Crow, age 32. He was drowned while trying to help his two sons swim in from theirstalled boat.Scene of the drowning was in a channel about 35 yards wide and in the Van Zandt County side near the Tangle-