B-17F-1-BO Flying Fortress 41-24352 “Holey Joe”. The B-17F was an upgrade of the B-17E. Outwardly, both types were distinguished primarily by the ten-panel fully-framed nose glazing on the "E" series. A molded, one-piece or two-piece all Plexiglas nose cone replaced this framed glazing on the "F" series (the two-piece cone had a nearly-transparent diagonal seam). Fully-feathering paddle-blade propellers were also substituted. Many internal changes were also made to improve the effectiveness, range, and load capacity of the Flying Fortress. Once placed in combat service, however, the "F" series was found to be tail-heavy. The combined weight, when fully combat-loaded, of the four rear gunners and their heavy .50 caliber ammunition, moved the bomber's center of gravity rearward from its original design point. This forced the constant use of the bomber's elevator trim tab, stressing that component to eventual failure. In combat the B-17F also proved...