With military aviation advancing at a blinding pace, the Army Air Corps recognized the need for a new modern, monoplane trainer. So, in 1939 the USAAC bought a single civilian STA-1, NC18907, and redesignated it as the XPT-16 (39-717; c/n 306, it is sometimes listed as a YPT-16) and set about evaluating it.
here) that includes a photo that must have been taken a fraction of a second later, as the tail has dropped just slightly.
What the USAAC found in the little two-seater pretty well met their needs, and so they ordered an additional 15 aircraft as YPT-16s. Only five of these were delivered (40-040 - 40-044) before the USAAC knew they had a winner, the order was converted and the rest were delivered as production PT-16s (40-045 - 40-054). These were operated by Ryan Aeronautical in San Diego under contract, training Army Air Corps pilots.
It soon became evident, though, that the one weak link in the design was the use of the 125-hp Menasco L-365 inline engine. To try to correct the problem, 39-717 was re-engined with a Kinner B-54 five-cylinder radial engine, redesignated the XPT-16A and shipped off to Wright Field for evaluations. This was followed by two Ryan-built, Kinner-powered prototypes (c/n 1000 and 1001) which carried the Ryan model STK; testing clearly showed that the Kinner engine significanly improved the aircraft's reliability and performance. Further aircraft were built under the PT-20 and PT-21 designation before the final PT-22 Recruit version, with which Ryan hit the jackpot, building over a thousand of them.
Sadly, 39-717 was scrapped in March, 1945.
|For comparison, here is an amateur snapshot of a generic production PT-22.|