The Junkers Ju 90 was a 40-seat, four-engine airliner developed for and used by Lufthansa shortly before World War II. It was based on the rejected Ju 89 bomber. During the war, the Luftwaffe used them as military transports. Some of the Ju 90s were converted into prototypes of the bigger Ju 290 transport and reconnaissance aircraft. The more powerful engines and other modifications to the Ju 90V5 and V7 were steps in this direction and the latter was converted into the Ju 290V3. The Ju 90V6 airframe was used in the construction of the Junkers Ju 390 V1.