The Sikorsky S-20 (named after its designer) or RBVZ S-XX (named after its manufacturer) was a Russian single-bay un-equal span two-seat biplane designed by Igor Sikorsky in 1916. Displaying some Nieuport influence it saw very little service during World War I. Five S-XX aircraft were built in September 1916 with the first two powered by the 100 hp Gnome rotary engine which had powered its predecessor the RBVZ S-XVI.
Made by Russo-Balt.