This page from a 1942 U.S. Navy Training School aircraft recognition manual illustrates the Boeing B-17E/F Flying Fortress, the U.S. Army Air Forces' iconic four-engine heavy bomber. Combining real photographs with standardized silhouette drawings, such manuals trained lookouts and gunners to instantly distinguish friendly aircraft from enemy types — a vital skill in preventing friendly-fire incidents during the rapidly escalating air war of World War II. Project: 218069