To avoid production delays due to engine unavailability, Stearman produced two sub-versions. The first of these, the PT-17, featured a stressed airframe with 300-hp engine capability, although it was standardly driven by the seven-cylinder, 220-hp Continental R-670-5 radial, while the second, the PT-18, was created with a 225-hp Jacobs R-755. Just 150 of the latter, however, have been built. Both appeared in 1940.

The type reached a major milestone on March 15 of the following year when the Army Air Corps took delivery of the 1,000th primary flight trainer in Wichita, the only Stearman style ever to have achieved such a production run. But the milestones, fueled by the war, mounted in speedy succession: only five weeks later, on August 27, the 2 2,000th aircraft, a PT-17, have been delivered to the Army Atmosphere Corps. These production rates could only be supported by an equally increasing
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