PZL P.11
The PZL P.11 was a Polish all-metal gull-wing fighter designed by Państwowe Zakłady Lotnicze under Zygmunt Puławski and first flown in August 1931. An advanced design when introduced, it was built in Poland as the P.11a, P.11b and P.11c and under licence in Romania as the IAR P.11f. Poland's main fighter in September 1939, it was by then outclassed, yet its pilots were credited with at least 110 victories in the campaign. A single P.11c survives, in the Polish Aviation Museum in Kraków.
Why It Mattered
When Germany invaded Poland in September 1939, the PZL P.11 was Poland's most important fighter aircraft. It was a descendant of Puławski's P.1, and the gull-wing layout it inherited became known abroad simply as the "Polish wing". History of War calls it an advanced design on its introduction that was nonetheless outdated and outclassed by 1939. Poland depended on it all the same: at the start of 1939 the Polish Air Force still had 185 P.11s on strength, and it equipped the fighter squadrons that would meet the invasion.
Design Notes
The P.11 had an all-metal structure and a high-mounted gull wing whose inner panels angled down to the fuselage sides, giving the pilot a much better view upwards than a parasol wing allowed. Its undercarriage was fixed. Work began in late 1930 under Puławski, but he did not live to see it fly: he died in a crash in March 1931, and his assistant Wsiewołod Jakimiuk took over the project. Polish versions used Bristol Mercury radials produced under licence; the P.11a used a Polish Skoda Works Mercury IV.S2. The P.11c's standard armament was two 7.7mm KM Wz 33 machine guns; two more guns could be carried in the wings, but only about 20% of P.11cs had all four guns.
Operational History
The first prototype made its maiden flight in August 1931. Production began with Romania's order for 50 P.11bs, placed in February 1933; the order was complete by the summer of 1934. Thirty P.11as followed for Poland, the first entering service in the autumn of 1934. The improved P.11c was delivered from the second half of 1935: fifty aircraft with the Mercury V.S2 engine and 125 with the Mercury VI.S2. Romania had purchased a licence to build the P.11b, but switched it to the P.11c; the resulting P.11f was built by IAR at Brașov, and about 80 were probably built in 1936–38. By the outbreak of war, twelve Polish squadrons flew the P.11c, split between the Pursuit Brigade defending Warsaw and the army air forces. Against the Bf 109 it lacked both speed and firepower, though a skilful pilot could still use its manoeuvrability to stay hard to hit. A P.11c of No. 121 Squadron scored Poland's first victory of the campaign on the morning of 1 September, downing a Junkers Ju 87 near Olkusz. The Polish fighter force as a whole claimed 126 victories in the campaign, the Pursuit Brigade claiming 42 of them; at least 110 victories were credited to the P.11 itself, against roughly 100 of the type lost. When the Soviet Union attacked from the east on 17 September, the 38 surviving P.7s and P.11s were evacuated to Romania.
Afterlife
Thirty-six of the evacuated P.11s were taken over by the Royal Romanian Air Force. Those veterans were not used in combat: a small number were used for training, and the rest were dismantled for spare parts. A single P.11c survives: the aircraft of the 121st Fighter Squadron stationed in Kraków, which resisted the German attack in September 1939. It is on display in the Polish Aviation Museum in Kraków, and the museum notes that this example is the only one preserved anywhere in the world.