<hi style=afpcap>The insatiable appetite for primary and basic training aircraft during World War Two lead the Army Air Force to obtain a wide selection of manufacturers to produce monoplane and biplane designs. The Ryan Aeronautical Company was one who elected to develop a low wing trainer with various designations to denote a change in powerplant. The basic PT-16 was also produced as the PT-20, PT-21 and PT-22 as illustrated. The latter version was that standardised for both the Army and the Navy.</hi>