PZL P.7 - Design and Development

Design and Development

The history of the PZL P.7 started in 1928, when a talented designer, Zygmunt Puławski designed an all-metal, metal-covered monoplane fighter, the PZL P.1. It introduced a high gull wing, giving a pilot an optimal view. The wing design was called the "Polish wing" or "Pulawski wing". The P.1 was powered by an inline engine, and developed a speed of 302 km/h, but remained a prototype, because a decision was made to use a licence produced radial engine in the Polish Air Force fighters. Therefore, the next model, the PZL P.6, flown in August 1930, was powered by the Bristol Jupiter VI FH radial engine. Both aircraft were well received in the aviation world with the press recognizing the P.6 as one of the world's top fighters; it won the American National Air Races in August–September 1931.

The PZL P.6 did not enter production, because the next variant, the more advanced PZL P.7 was developed. The first prototype was basically the P.6 with a more powerful Bristol Jupiter VII F engine. Due to the use of a compressor, it had better performance at higher altitude. The prototype was first flown in October 1930 by Bolesław Orliński. Initially engine cylinders had individual cylinder clearance fairings. In autumn 1931, Ludomił Rayski lost the prototype in a crash. The cause is undetermined but Rayski was able to bail out successfully. After some changes, most noticeably adding a wide Townend ring to the engine and making the tail slimmer, the second prototype, built in autumn 1931, was accepted for production with the designation P.7a. It also featured a redesigned wing with slightly increased span, taken from the PZL P.8, and featuring shorter ailerons and smooth upper surfaces instead of ribbed ones. Since it was the only variant, it was commonly known as the P.7.

The first series P.7a were built in mid-1932, the whole series of 149 (plus two prototypes) was completed in 1933. They carried numbers 6.1 to 6.151. The Polish Air Force received the P.7a in 1933.

After designing the P.7, Puławski started to develop his design with more powerful engines, and the result was the PZL P.11, built in a production series. Puławski personally was an inline engine fan, designing a new fighter, the P.8, with a slim silhouette, powered with an inline engine. It was able to reach a speed of 350 km/h. A planned variant was to be designated the P.9. Unfortunately, in March 1931 Puławski died in an air crash, and the inline engine fighter design was cancelled in a favour of the radial engined P.11. The P.11 became the standard Polish fighter. In parallel with the P.11, the PZL P.24 export variant was also developed in 1932.