The P.11/IV equipped with the French Gnome et Rhône Mistral 9Ker engine (500/550KM), a narrow Townend ring, a three-bladed propeller and elegant fairings on wheels were exhibited at the 13th International Air Show in Paris in 1932. It became the model for PZL P.11b, exported to Romania (1933–1934). These planes were the first mass-produced P.11s (later they had a two-bladed propeller and no wheels fairings). In turn, after minor modifications to the tail and the introduction of the exhaust manifold in the leading edge of the engine cover, the PZL P.11/III prototype became the model for the PZL P.11a, 50 of which were made and delivered in 1934. It was not a machine without flaws, some of them inherited from the P.7a, e.g. not the best visibility from a cramped cabin and difficulties with tracking series from low positioned machine guns. In addition, exhaust fumes penetrated the cockpit, causing health problems for the pilots. Therefore, at the turn of 1933 and 1934, the military authorities became interested in the P.11/V prototype prepared for export. It was actually a new plane, which was supposed to improve the competitiveness of the P.11 in the fight for orders, especially in terms of speed, stability and utility values. The differences from the P.11a were very serious: the engine was placed 13 cm lower. The truss part was extended behind the cockpit. It was not visible, because the sheets kept their round cross-section there. However, this facilitated access to most important installations – it was possible to remove whole sheet covers. The position of the pilot’s seat was raised (by 5 cm) and it was retracted 30 cm. This forced the use of new belts, which allowed the pilot to lean freely in a much more spacious cockpit – thus it was the first Polish plane with inertial pilot belts. This had a serious impact on safety – in the case of an emergency landing, facial injuries were much less frequent than, for example, in PZL P.7a (or in Armstrong-Whitworth Siskin, which was then withdrawn in Great Britain, which left the pilots with a broken nose after harder landings, the so-called “siskin nose”). The fairing behind the cabin was extended to the base of the rebuilt tail. There was a place for a radio station (not all copies had one). The new shape of the vertical tail, together with the fairing, improved stability. The wings were redesigned and now they could fit two additional machine guns. The Gnome et Rhône Mistral 9Krse engine (560/600 HP) was provided for the export version. It was produced under license in Romania under the designation of P.11f (according to various data, from 70 to 95 copies were made). The Polish version was to have a Skoda Bristol Mercury VS2 engine (565/600 hp). It was planned to use a reinforced Bristol Mercury VIS2 engine (605/645 hp), but it has been confirmed that this unit was mounted only on the plane with serial no. 8.1293. One hundred and seventy five aircrafts were completed to this standard and bearing the name PZL P.11c. They were sent to units at the turn of 1935 and 1936, when the trials for the production of its export version were already beginning… Well, was it a replacement or successor? The P.24 was treated from the beginning as an export option, i.e. a substitute for the P.11c in this market. On the other hand, in 1938–1939, when looking for an aircraft to replace the rapidly aging “eleven”, all machines were compared to the P.24 as an aircraft that “we could have anytime.” Therefore, temporary problems with P.50 Jastrząb resulted in the suspension of the project, which seemed to “not promise progress to P.24.”
So we were left with “eleven” (which, even after a significant modernization which was the P.11g with the Bristol Mercury VIII engine, stubbornly did not want to exceed 400 km/h). Polish pilots set off to fight on machines that were quickly aging in four years, but they rapidly became obsolete with the entry into service of the Messerschmitt Bf 109E. An additional problem was the need to carry out repairs. Frequent cracking of engine beds in 1938 resulted in the suspension of training until the replacement (winter 1938/1939) of these elements in most of the units. This also explains why the September machines were darker than those from previous periods – almost all of them underwent airframe renovation. By the way, wing MGs were removed from some of the machines armed with four machine guns4. The reverse process was happening with the radio stations. Unfortunately, the same cannot be said for heavily worn engines.
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