06/30/2012. Remarks by Johan Visschedijk: "Sleek and shining, like a model turned from solid silver, the first Ryan S-T caught the attention and affection of the flying world in 1934 and has held it ever since. The S-T (for Sport-Trainer) first flew June 8, 1934 and embodied the features most desired by sportsmen and training schools alike; high performance, minimum and easy maintenance, low operating costs and a striking appearance. At the controls for the first S-T flight was John Fornasero, Ryan's Chief Pilot, who took off from Lindbergh Field, San Diego, California.

The S-T was an open, two-seat, tandem cockpit, low wing type, principally of metal construction and powered by a Menasco B-4 Pirate engine of 95 hp. The first S-T was c/n 101, X14223 (later simply 14223, then NC14223 as certification was granted). However the basic S-T, like any great airplane, was not destined to remain "basic" very long. Shortly after the first one was built, S-T-A was introduced, powered by an 125 hp Menasco C-4, and in 1936 the S-T-A Special was introduced, fitted with the 150 hp supercharged Menasco C-4S.

Other versions included the S-T-B (c/n 109, X14953) built in 1935 as a single-seater, two S-T-W, c/n 337, NX18920 powered by a Warner 125 hp Scarab and c/n 338, NX18919 powered by a Warner Super-Scarab of 160 hp. Both S-T-Ws were built in 1939. In 1940 a further variant the S-T-K, c/n 406, X18924 powered by a Kinner B-5 engine of 125 hp was built. Export versions included the S-T-M series which was developed from the S-T-A-1, built for the USAAC as a trainer, beginning with the XPT-16.

The trim S-T series proved to adapt quite well to the training role, and in 1938, Ryan School of Aeronautics was advertising the fact that eight of the eleven planes used there were "modern, metal ships", of the S- T type. Other potential users were quick to note this and several other countries acquired the planes for trainers, or "light fighters". Exported as the S-T-M, Mexico, Honduras, Union of South Africa, Guatemala, Netherlands East Indies and China all used the little Ryan.

The S-T-M listed as a "trainer or light fighter" by Ryan, was powered by the 150 hp Menasco C-4S and was essentially the same aircraft as the S-T-A Special. When included, armament consisted of two machine guns mounted outside the landing gear strut below the wing, firing outside the propeller arc.

In June, 1939 the Ryan Aeronautical Company received an USAAC contract for one standard trainer. Initially flown as NC18907, it was delivered under the serial 39-717. The XPT-16 was Ryan's entry into the US military training program and was a significant event in that it was the first monoplane used by the Army as a primary trainer. A thorough evaluation was undertaken and a further fifteen aircraft were ordered as YPT-16. Power was the 125 hp Menasco L-365-1 (military designation for the C-4 engine) with the addition of an engine starter.

As military expansion increased, the Army designated Ryan, Stearman and Vultee as prime manufacturers of their standard trainers. The fifteen YPT-16s were operated at Lindbergh Field, San Diego, California by the Ryan School of Aeronautics, which became the first of many Civilian Pilot Training (C.P.T.) Schools operated during the war.

First class of Air Corps Training Detachment to train in the YPT-16 began on August 19, 1939. Prior to this all training had been given at the Air Corps Training Center at Randolph Field, Texas. So, the S-T continued to lead with new innovations. The basic program was twelve weeks of flight instruction consisting of 65 hours flying time and 225 hours of ground school.

There followed a period of development of the basic S-T-A into what was to eventually become the PT-22 which was the most widely produced version of all of the Ryan planes. In 1940 an order was placed for forty of a basically similar model designated PT-20. This was the same aircraft and engine as the YPT-16 with the principal outward difference being a larger cockpit with external longerons, which allowed more room for parachutes.

During 1941, and with the order of 100 PT-21 aircraft, the PT-20 and PT-16 types in service were modified to more or less standardize the aircraft then in service. The Kinner R-440-1 engine was installed in a streamlined nose fairing with projecting, uncowled cylinders, and the wheel and tail fairings were removed as they gave trouble in the rugged service of a primary training school.

Sixteen of the YPT-16s were converted to PT-16A, and 27 PT-20 airplanes became PT-20A. The PT-21 was delivered with the Kinner R-440-3 engine of 132 hp, while the metal wheel coverings were quickly discarded in service. The PT-20B was a Menasco-powered aircraft and three were so modified.

As the war tempo grew, the Army and Navy standardized on the S-T-3KR or PT-22 Recruit as an even more powerful trainer. Equipped with a 160 hp Kinner R-540-1 engine, and delivered without wheel spats or fairings over the gear struts, the PT-22 was otherwise identical to the PT-21. Navy designation for the PT-22 was NR-1 and 100 were produced.

PT-22s went into service at the C.P.T. schools across the country, including Ryan operated schools at San Diego and Tucson, Arizona. The Netherlands order for 25 S-T-3s was taken over by the USAAC in 1942 as the PT-22A. Modified after delivery, some 250 PT-22s were to become PT-22C with a change from the R-540-1 to the -3 engine.

In 1942 production ended on the S-T series. At this time Ryan was given a contract to develop a version of the trainer using non-strategic materials. The result was the S-T-4, which was virtually a new airplane built almost entirely of plastic-bonded wood. Five of these were delivered in 1942-1943 as YPT-25, however, production was not undertaken.

Other variants included the S-T-3S, which was actually the S-T-3 PT-21 prototype NX18925 equipped with Edo floats. The S-T-3KR was the civilian version of the PT-21/PT-22 and was assigned TC 749. Civil designation for the Kinner R-540 was R-55, rated 160 hp at sea level at 1,800 rpm.

The pictured aircraft was subsequently re-engined with an 125 hp Kinner B-54 five-cylinder radial (military designation R-440), and redesignated to XPT-16A. On July 31, 1942, the aircraft was deregulated to CL-26 status, becoming a maintenance trainer. It was scrapped on March 27, 1945."