Boris Sergeyevich Stechkin (; 5 August 1891 â 2 April 1969) was a Russian and Soviet scientist, engineer and inventor. He developed a theory of heat engines and was involved in construction of many Soviet aircraft engines. He was also co-developer of Sikorsky Ilya Muromets (the first four-engine airplane and bomber, 1913) and Lebedenko's Tsar Tank (the largest armored vehicle in history, 1916âÂÂ1917). He died in Moscow on 2 April 1969.