 The B-17 Flying Fortress was perhaps the most well-known American heavy bomber of the Second World War (1939/41-1945).It achieved a fame far beyond that of its more-numerous contemporary, the Consolidated B-24 Liberator.The first pre-production Y1B-17 Fortress was delivered to the 2d Bombardment Group, Langley Field, Virginia on 11 January 1936; the first production B-17B was delivered on 29 March 1939, also to the 2nd Bombardment Group.