The P.Z.L. P.6 was one of two radial powered developments of the P.1 fighter that were produced at the same time in 1929-30, but lost out to the second model, the high altitude P.Z.L. P.7
The P.Z.L. P.1 was an impressively advanced design for a gull winged fighter that had been produced by Zygmunt Pulawski. Work on the prototypes of the P.1 began at the start of 1929, and it made its maiden flight in September 1929, powered by a inline engine. However by that point work had already moved on to the P.6 and P.7 projects. The Polish Department of Aeronautics was hoping to negotiate a licence to produce the Bristol Jupiter engine in Poland, and the Polish Air Force preferred radial engines. Work on the radial powered P.6 and P.7 began in mid-1929, just as the prototypes of the P.1 were ready to fly.
The two new designs were fairly similar, but the P.6 was to be powered by a low-altitude Jupiter VI engine and the P.7 by a high altitude Jupiter VII with supercharger.
Although the two new aircraft looked fairly similar to the P.1, most of the design was changed in some way. They kept the scissor-type undercarriage, which had shock absorbers mounted inside the fuselage, and the tail. The wing retained the gull wing shape, with the main part carried above the top of the fuselage, but attached to it by inner panels that angled down to connect to it between the radial engine and the cockpit, but the new wing was smaller than on the P.1. The fuselage was totally redesigned, and the largely rectangular design from the P.1 was replaced with a semi-stressed skin fuselage with a circular cross section. This matched the circular shape of the new engine, and also allowed the fuel tanks to be moved from the wing to the fuselage.
Work on two P.6 and two P.7 prototypes began early in mid-1929. The new fuselage was difficult to construct, and the first prototype, the P.6/I, didn’t make its maiden flight until August 1930. It was powered by a 450hp Jupiter VI.FH radial engine with a narrow chord Townend ring developed by PZL, and fairings behind each cylinder head.
The second P.6 prototype, P.6/II, was completed early in 1931. It was almost identical to the first, apart from a modified exhaust system.
The P.6/I was exhibited at the 1930 Salon International de l’Aeronautique in Paris, where it made quite an impression. In the following year it also impressed at the National Air Races at Cleveland, Ohio, although it didn’t actually enter any of the races, but instead was used to give demonstrations.
During August 1931 the P.6/II was demonstrated to Prince Nicholas of Romania and a party of high ranking Romanian military officers. They were impressed enough to begin negotiations to purchase the type, and would eventually buy a number of the improved P.Z.L. P.24.
The P.6 never progressed beyond the prototype stage, but the P.7 was ordered into production, allowing the Polish air force to be the first in the world to fully convert to an all-metal monoplane fighter.
Engine: Bristol Jupiter VI.FH radial engine
Span: 33ft 9.75in
Length: 23ft 5.75in
Height: 9ft 0.25in
Empty Weight: 2,002lb
Loaded Weight: 2,988lb
Maximum Speed: 181.4mph at sea level; 177mpg at 12,467ft
Climb rate: 2min 5sec to 6,561ft; 9min 1 sec to 16,404ft
Range: 373 miles
Guns: Two Vickers ‘E’ guns re-bored to 7.92mm