The Boeing B-17 Flying Fortress is an American four-engine heavy bomber used by the United States Army Air Forces and other Allied air forces during World War II. Forty-five planes survive in complete form, including 38 in the United States. Fewer than 10 are airworthy. Of the 12,731 B-17s built, about 4,735 were lost during the war. After the war, planes that had flown in combat missions were sent for smelting at boneyards, such as those at Walnut Ridge and Kingman. Consequently, only six planes that survive today have seen combat. Most of the other survivors were built too late to see active service and then were used through the 1950s and 1960s in military and civilian capacities. Many are painted to represent actual planes that flew in combat. (en)