PZL P.II – FIRST TO FIGHT

All photos Henryk Clapa collection

Jan Polc

Polish fighter pilots were the first airmen to defend their country against Nazi Germany in September 1939. They flew the elegant PZL P.11 with its characteristic gull-wing - a modification of the shoulder-mounted wing. This positioned the wings just above the upper edge of the fuselage, connected to the fuselage by means of wing roots that are bent downwards. When viewed from the front, the wing roots form a'V'and the wing resembles that of a gull. The advantage of this wing arrangement is improved visibility for the pilot, and in addition, aircraft with these wings turned out to be particularly agile. The wing came to be named after its inventor, Polish engineer Zygmunt Puławski, who initially devised the concept that was copied by other producers in various countries. Sadly, Puławski, a talented aircraft designer, lost his life in an accident at the age of only thirty.

The history of the PZL (Państwowe Zakłady Lotnicze - State Aviation Works) P.11 began in 1929, when Puławski commenced work on designing an all-metal structure, metal-covered monoplane fighter aircraft. Prior to this, Polish aviation construction had concentrated on the licensed production of foreign-designed aircraft, particularly French. Puławski's all-metal approach therefore represented a considerable step-change for Polish industry.

This initial aircraft design was designated the P.1, which first flew in September 1929. The aircraft demonstrated an outstanding performance against its peers, including the British Bristol Bulldog and the French Dewoitine D.27, when it achieved first place at an international air competition held in Bucharest, Romania. The design generated considerable interest around the world, such that the general layout started to be called the 'Polish wing' or 'Puławski wing. The Polish War Ministry objected to the aircraft's use of the licence-built Hispano-Suiza V inline engine, citing insufficiently proven reliability and expense. Accordingly, a second prototype, the P.6, was completed the next year and featured several differences from Puławski's original, including the adoption of a radial engine. However, during testing the P.6's engine was plagued by overheating issues, and this disappointment led air force officials to order further development of the design. The new fighter, now designated P.7, fulfilled its expectations, and the Polish Air Force ordered 150 aircraft.

In the meantime, Puławski continued improving his design, concentrating on the use of more powerful engines and refining the P.7's design. The first prototype of this improved P.11/1 powered by a Bristol Jupiter engine took its first flight in August 1931, shortly after Puławski's premature death in the crash of another of his projects, the PZL P.12. Work on P.11 development was continued by Wsiewołod Jakimiuk, who developed two more prototypes, the P.11/II and P.11/III, both powered by Bristol Mercury engines instead of the previous Jupiter. This line of the prototypes led to the P.11/VI, which was basically representative of the series production PZL P-11.

The P.11 had an open cockpit, protected by a plexiglass windshield. Instrumentation included polish-built navigation and engine control gauges (although the compass was German), while safety equipment included an arrangement of several flame dampers for the engine exhausts, a flare gun, and oxygen tanks for the pilot. It was also fitted with an internal fuel tank, positioned inside the fuselage, which could be jettisoned in case of fire or other emergency. The all-metal fuselage of the P.11 was matched to a twin-spar, shoulder-mounted wing via bearers set upon the upper portion of the first two fuselage frames. The wing and the tail employed a similar construction making use of Daude-type, hollow rivets, a corrugated duralumin-sheet exterior and solid duralumin struts with plates for strengthening. The undercarriage legs were V-shape streamlined struts, equipped with Avia-type oleo-pneumatic shock absorbers and braced with steel wire. For armament, the P-11 was equipped with a pair of 7.92mm machine guns mounted in the sides of the fuselage. About a third of all P.11c model fighters were also equipped with two additional machine guns in the wings.