The Tupolev MTB-1 (known originally as the MDR-4 and internally to Tupolev as the ANT-27) was a patrol flying boat built in the Soviet Union in the mid 1930s. It was a refined version of the unsuccessful Chetverikov MDR-3. The revised design retained the MDR-3's hull but added a newly-designed fully-cantilever wing a new tail and a new engine installation featuring two tractor and one pusher unit. Trials began in March 1934 but the prototype was destroyed during one take-off.
Made by Tupolev.