Sikorsky Russky Vityaz

From Wikimedia Commons, the free media repository

The Sikorsky Russky Vityaz (Russian Knight) or Le Grand (The Great), later designated as Sikorsky S-21, was the very first usable four-engined aircraft in the world. The large biplane was designed and built by the Ukrainian engineer Igor Sikorsky in Imperial Russia in the spring of 1913.

Sikorsky S-21 Russky Vityaz (Le Grand) early version

Sikorsky S-21 Russky Vityaz (Le Grand) improved version