1918 biplane. This early aeroplane is a biplane, a fixed-wing aircraft with two main wings. Biplanes were the most successful early aircraft and from 1914 to 1925, almost all aircraft were biplanes. This was because monoplanes (single winged) at the time had less rigid wings. The fact that the two wings in biplanes were braced to each other meant that they were more stable and were less susceptible to warping than the monoplane wings.