The P.W.S.6 was an improved version of the earlier P.W.S.5, equipped with Handley Page leading edge slots, but despite being a promising design it only reached the prototype stage.
The P.W.S.5 had been designed in response to a Polish Department of Aeronautics requirement for a two seat observation/ liaison aircraft to be powered by a Polish built 220hp Wright J.5 radial engine that was issued in 1927. P.W.S. responded with a design for a biplane, and like Lublin and P.Z.L. was rewarded with a contract for two prototypes and a structural test airframe, followed by five pre-production aircraft. The original P.W.S.5 suffered from stability problems, so the second prototype was modified to become the P.W.S.5a. This solved the stability problems, but its performance was disappointing, and it lost out to the Lublin R-XIII for the observation/ liaison order. The five pre-production aircraft were completed, but were used as operational trainers.
In the second half of 1927 two P.W.S. engineers, Grzedzielski and Bobek-Zdaniewski, began work on an improved version of the P.W.S.5. This was to use Handley Page leading edge slots, a narrow gap between the leading edge of the wing and the main surface, which improves the lift provided by a wing and reduces the stall speed (although at the expense of reducing the cruising speed and fuel efficiency). This new design, the P.W.S.6, had the same basic design as the P.W.S.5, although with fairings to give the fuselage a circular cross section instead of the rectangular section of the P.W.S.5, as well as high aspect ratio wings with rounded tips. Leading edge slots were installed along the full length of the upper wing, while ailerons were installed on the trailing edge of the lower wing.
Although Handley Page slots had been developed at the start of the 1920s they were still a fairly new technology, so a scale model of the P.W.S.6 was produced and used in wind tunnel tests. These were encouraging enough for the company to be ordered to build a prototype, which was completed by 1930. The aircraft performed well in its trials, and demonstrated good STOL and aerobatic performance. However by this point the Polish Air Force had already ordered the Lublin R-XIII monoplane as its observation aircraft, so the P.W.S.6 didn’t enter production. The company also lost interest in using slots, but some of the improvements introduced on the P.W.S.6 were later used on P.W.S. biplane trainers.
Engine: Skoda built Wright Whirlwind J.5 radial engine
Span: 31ft 6.25in
Length: 22ft 11in
Height: 9ft 8.25in
Empty Weight: 1,764lb
Normal Loaded Weight: 2,590bl
Maximum Speed: 115.6mph at sea level; 111.2mph at 3,280ft
Climb rate: 14min 41sec to 9,842ft
Guns: Lewis gun in observers position