LWS-6 Żubr

Origins Work on what would become the LWS-6 originally started in 1932 as the PZL.30, a 12-passenger airliner. While the airline did not outwardly indicate interest in the project, Polish aviation authorities opted to sponsor its development in the hope that LOT would change its mind as it neared completion. Such hopes were in vain, however, as in 1935, LOT opted to purchase American-built Douglas DC-2 airliners instead. Another avenue for the project had presented itself in the form of an official requirement for a new medium bomber for the Polish Air Force; Ciołkosz himself proposed producing a bomber derivative of his airliner project. Continuing the PZL.30's development also enabled the project to act as a fallback option in the eventuality that the more advanced bomber encountered insurmountable technical issues. Thus, the company was instructed to proceed with constructing a single prototype. It was flown in September 1936. The aircraft was accepted for a limited production run by the LWS state factory in Lublin, for which Ciołkosz was appointed the technical director and project lead. In older publications there could be found a designation LWS-4, but it does not appear in any documents and the aircraft's correct designation was LWS-6. Design changes It was planned to produce 16 aircraft for the Polish Air Force, with the designation: LWS-6 Żubr. To remedy the issue, the wing was redesigned with greater reinforcement, but this measure increased the aircraft's overall weight, which in turn meant that the LWS-6 had a smaller bomb load than expected while other performance areas were also hampered. while deliveries to the Polish Air Force commenced in early 1939. Aside from the Polish Air Force, the Romanian Air Force showed an interest in the Żubr prototype during 1936 and, at one point, was reportedly considering the purchase of up to 24 aircraft that could have been powered by French-supplied engines. Following the fatal loss of the Pegasus-powered prototype on 7 November 1936, which had resulted the deaths of all on board, including two Romanian officers, Romania placed an order for the rival PZL.37 Łoś instead. ==Design==

The LWS-6 Żubr was a conventional high-wing cantilever twin-engined monoplane. It featured an unorthodox mixed construction approach, being largely composed of both metal and wood. The fuselage, which had a rectangular cross-section, was divided into two sections; the forward section had a duralumin structure while the remainder of the structure used welded tubular steel. These engines drove three-bladed Hamilton Standard metal propellers. The engines were license-manufactured as PZL Pegaz 8. The LWS-6 was operated by a crew of four: a pilot, commander-bombardier, radio operator and a rear gunner. The bombardier was accommodated in the aircraft's glazed nose, the position being provisioned with a forward-facing turret armed with twin machine guns that had a distinctive pointed "beard" directly beneath it. The pilot was seated underneath a sizable canopy in a forward position on the upper fuselage, which was also somewhat offset to the left. The radio operator was seated inside the fuselege. In training role, additional crew member took place in the pilot's cockpit on folding seat. The rear gunner operated a semi-retractable upper dorsal turret armed with twin machine guns that elevated to a working position, along with a "trap" ventral position that operated in an identical manner. The bombload was intended to be primarily carried within an internal bomb bay on multi-storey racks; external racks were also tested for an expanded bombing capacity. The aircraft was designed to carry 1200 kg of bombs in the bomb bay (8 bombs 50 or 100 kg), under the fuselage (4 bombs 50 or 100 kg) and under wings (4 bombs 50 kg), but maximum take-off weight limited the load to 440-660 kg. ==Operational history==

Between 1938 and 1939, a total of 15 LWS-6 bombers were delivered to the Polish Air Force. From the outset, the type was considered to be obsolete; instead of being assigned to frontline combat squadrons, the newly-delivered aircraft were allocated to training units, primarily to the 213th Training Bomber Escadrille in Małaszewicze and a training escadrille of the 1st Air Regiment. In Polish service, several shortcomings were identified on the LWS-6, such as the occasional uncommanded retraction of the undercarriage during landing. As a result, some crews would reportedly choose to fly with the undercarriage permanently locked down. The type was exclusively used for training. Production model of the Żubr was considered safe aircraft, with good flight characteristics, and only one crashed before the war due to pilot's error, however, without fatal injuries. During the Invasion of Poland in September 1939, no Żubrs were recorded as having been used in actual combat. They were largely grounded, being unsuitable for operations at full-loaded weight from the temporary operational landing fields commonly being used, while flying in a lightened condition would have provided virtually no payload capacity. The Soviet Union also captured four aircraft during their own invasion of Poland. These were subsequently operated by the Soviet Air Forces for a time as communication aircraft. ==Operators==

; • Luftwaffe — operated captured aircraft for training purposes. ; • Polish Air Force — used in non-combat roles, primarily training. ; • Soviet Air Force — used four captured aircraft for communication. ==Specifications (LWS-4)==