 During the 1920s the high-wing parasol monoplane vied with the traditional biplane.It was not until the arrival of the American Boeing P-26 Peashooter in 1932 — nearly fifteen years after the first low-wing fighter to enter limited military service, the all-metal airframe Junkers D.I had entered service with the "Luftstreitkräfte" in 1918 — that the low-wing monoplane began to gain favour, reaching its classic form in such designs.These were pioneered in late 1933 by the Soviet Union with the Polikarpov I-16 fighter, powered initially with an American Wright Cyclone nine-cylinder radial engine.