Over 10,000 Stearman trainers were built by Boeing's Wichita Division, which had purchased the Stearman Company in the late 1930s. These Kaydets, along with Fairchilds and Ryans, served as the backbone of U.S. Army and Navy primary training in World War II. The original U.S. Army Kaydet was the PT-13 with a 220 Lycoming R-680 engine. The only complete standardization of an Army and Navy production design aircraft during World War II was achieved with the Boeing-Stearman E-75, which served the Army as the PT-13D and the Navy as the N2S-5. Highlighted in this image is the vertical stabilizer of the Boeing-Stearman N2S-5 Kaydet.