The U.S. Naval Aircraft Factory at Philadelphia, Pennsylvania, was authorized in 1917 and established in early 1918. Its first, and major, task was the construction of 150 Curtiss H-16 patrol flying-boats. Built improved H-16s as F-5L, as well as Hanriot seaplanes and Loening two-seat monoplanes. Original designs of NAF include the PT-1/2 torpedo seaplanes of 1922; TS-1/3 carrier-based biplane fighters of 1922; and extensively-built N3N-1/3 primary trainer biplanes, which originated in 1934 and remained in service for 27 years. Production in Second World War included 300 Vought-designed OS2 N-1 observation/scout monoplanes, and 156 Consolidated PBN Nomads (better known as the PBY Catalina).