Boeing N2S Stearman Yellow Peril airplane model. The famed Stearman Model 75 has its roots in the earlier Model 70, which was chosen in 1934 as the U.S. Navy's primary trainer. At a time when biplanes were becoming a thing of the past, the Model 70 offered the fledgling pilot a steady and sturdy steed. Designed and built in only 60 days, the prototype Model 70 could withstand load factors much higher than were expected to occur in normal flight training.
The U.S. Army and Navy tested the prototype in 1934. At the conclusion of these tests, the Navy ordered the aircraft while the Army decided to wait for the introduction of the improved Model 75 appearing in 1936. Over the next decade, the Army received nearly 8,500 Stearmans in five different variants. The difference among these versions were the engines fitted, Kadets, were fitted with Lycoming (PT 13), Continental (PT 17) or Jacobs (PT 18) radial engines. The U.S. Navy took delivery of their first Stearman (called the NS-1) in 1934. Powered with the obsolete but readily available Wright R-790-8 engine, the NS-1 proved its worth as a primary trainer. The Navy purchased several thousand of an improved model, the N2S. The N2S was built in five sub variants, each variant being equipped with a different model engine.