The Ford Trimotor using all-metal construction was not a revolutionary concept, but it was certainly more advanced than the standard construction techniques of the 1920s. The aircraft resembled the Fokker F.VII Trimotor (except for being all-metal which Henry Ford claimed made it "the safest airliner around"). Its fuselage and wings followed a design pioneered by Junkers during World War I with the Junkers J.I and used postwar in a series of airliners starting with the Junkers F.13 low-wing monoplane of 1920 of which a number were exported to the US, the Junkers K 16 high-wing airliner of 1921, and the Junkers G 24 trimotor of 1924. All of these were constructed of aluminum alloy, which was corrugated for added stiffness, although the resulting drag reduced its overall performance. So similar were the designs that Junkers sued and won when Ford attempted to export an aircraft to Europe. In 1930, Ford countersued in Prague, and despite the possibility of anti-German sentiment, was decisively defeated a second time, with the court finding that Ford had infringed upon Junkers' patents.