The LWS-6 Żubr (PZL.30, wisent (En. Bison) ) was a Polish twin-engined medium bomber, produced by the LWS factory before World War II. A short series was used for training only, because it was inferior to the contemporary PZL.37 Łoś design.
A total of 15 LWS-6 bombers were delivered to the Polish Air Force in 1938–1939. From the outset, they were considered obsolete, and were assigned to training units, mainly to the 3rd Training Dyon. In operational service, the LWS-6 revealed several faults, for example, the undercarriage retracted on some aircraft during landing. Reportedly, the crews later flew with the undercarriage permanently locked down. As training aircraft they had their armament removed. There was only one crash, however, without fatal injuries.
During the invasion of Poland in 1939, Żubrs were not used in combat. Several were destroyed on the ground, along with many other training aircraft. The Germans captured several LWS-6s, including the twin-tailfin prototype, and used them for blind flying training until at least 1942 (among others, in Blindflugschule Schleissheim). The Luftwaffe service of this bomber was longer than the Polish one.
The Soviets captured four aircraft after their invasion of Poland and subsequently used them as communication aircraft.