PZL P.11

Development

The first prototype P.11 flew in August 1931, after Pulawski's death in an air crash. It was followed by two slightly changed prototypes. The first variant ordered by the Polish airforce was P.11a, considered as an interim model and built in a series of 30. Its shape and construction were very similar to P-7. It was fitted with a radial engine Bristol Mercury IV S2 575 hp (429 kW) produced in Poland under licence. The final variant for the Polish airforce, P.11c, had a new, refined hull, with the radial engine lowered, to give the pilot a better view. The central part of wings was also modified. The production of P.11c started in 1934, and 175 were produced. The first series of approximately 50 P.11c were fitted with engines Bristol Mercury V S2 600 hp (447 kW), the rest with Mercury VI S2 630 hp (470 kW).

Apart from Poland, Romania showed interest in the new design. Even before P.11a, 50 aircraft designated P.11b were produced for the Romanian Air Force and delivered in 1932. They were fitted with engines Gnome-Rhone 9Krsd (595 HP), otherwise they were similar to P.11a. After P.11c had been developed, the Romanians decided to buy a licence and produce the new model at IAR factory. As a result, from 1936 the Romanians built 70 aircraft IAR P.11f, being a variant of P.11c with an engine Gnome-Rhone 9Krse (610 HP). The Romanians then produced another Polish fighter, PZL P.24, developed from P.11 exclusively for export. Some other countries were interested in buying P.11, but finally Bulgaria, Greece and Turkey bought P.24 instead.

When P.11 entered service, they were modern fighters, similar to or better than contemporary world designs. However, due to the quick progress in aircraft technology, they became obsolete by 1939. Unfortunately, they remained the only Polish fighters in service. When it became apparent that a modern fighter PZL P.50 Jastrzab would not be ready in time to replace P.11c, the building of an upgraded version P.11g Kobuz was considered as a stop-gap measure. This was to have a new engine Bristol Mercury VIII 840 hp (626 kW) and a closed cab. Only the prototype of P.11g was flown before the war, in August 1939. It developed a speed of 390 km/h only.

Combat use

By September 1, the fighter escadres had been deployed to field airfields, so they were not bombed by the Germans. During the campaign, P.11 fought against more modern German bombers and fighters. Not only German fighters Bf 109 and Bf 110 were faster and better armed, but also most German bombers were faster than P.11c. Since the planes were intensively used, their maximum speed was still lower than the theoretical 375 km/h. P.11a were in an even worse situation.

On the other hand, Polish planes had better maneouvreability. P.11 had a strong construction and also could operate from short fields, even rough ones. It was also of a very durable construction and could dive even at 600 km/h without risk of wings falling apart. Theoretically the only limit in maneouvres was the pilots ability to sustain high g. Despite the German superiority, P.11 managed to shoot down a considerable number of German aircraft, including fighters, but suffered heavy losses as well. The exact numbers are not fully verified, but it appears that at least one German plane shot down for each P.11 lost (a figure of 141 German planes is often given as compared with 118 planes lost).

The first aircraft shot down in World War II, on September 1 at dawn, was a PZL P.11c of Capt. Mieczysław Medwecki shot down by a German Ju 87. The first Allied air victory was achieved 20 minutes later by Medwecki's wingman, Wladyslaw Gnys who shot down two Dornier Do 17E with his P.11c. It was also the first airplane to successfully ram an enemy plane in WWII.

Most of P.11 were destroyed in 1939. 36 were withdrawn to Romania and were taken over by the Romanian Air Force. They were not used in combat, due to
their obsolescence, and only small number was used for training while the rest were dismantled for spare parts. Some planes were used by the Germans for training. Two PZL P.11 were captured by the Red Army and used for testing. One landed in Hungary and was used as a glider towing plane by the University of Technology in Budapest.

Technical description

Note: the horsepower data of engines differ in publications.

Specifications (variant described)

General characteristics