Ryan YPT-16
"A military version of the civilian Ryan STA, the YPT-16 became the first monoplane acquired by the U.S. Army Air Corps as a primary trainer. The Air Corps ordered 15 YPT-16s after purchasing a single Ryan STA-1 in 1939 for testing as the XPT-16. From 1940-1942, the Air Corps bought nearly 1,200 more similar Ryan trainers as PT-20s, PT-21s and PT-22s. "