Possessing an all-metal structure, metal-covering, and high-mounted gull wing, the type held the distinction of being widely considered the most advanced fighter aircraft in the world at the time of its introduction into service.

The primary individual responsible for their development was Polish aeronautical engineer Zygmunt Puławski, who has been attributed as having designed many of their innovative features.

While most of the world's air forces still operated biplanes in the early 1930s, the P.11, like previous aircraft in the Puławski family, used a high-mounted and aerodynamically clean gull wing that produced less drag and provided the pilot with a superior field of view.

The PZL P.11 served as the basic fighter of the Polish Military Aviation in the second half of the 1930s, including during the German-Soviet invasion of Poland.

However, as a consequence of the rapid advances in aircraft development during the late 1930s (seen in such fighters as the Messerschmitt Bf 109), it was outclassed by its rivals at the onset of the war.

[1] A significant number of Polish P.11s were destroyed on the ground in the first days of the Second World War; however, many fighter squadrons took up an unequal fight, achieving some successes.

[1][4] The history of the PZL P.11 started in 1929, when Polish aeronautical engineer Zygmunt Puławski began work on the design of an all-metal, monoplane fighter aircraft.

[5] While the majority of the world's forces were still using biplanes, the P.1 had a high-mounted and aerodynamically clean gull wing, which provided the pilot with a superior field of view.

[7] It demonstrated its outstanding performance compared to contemporary aircraft, such as the British Bristol Bulldog and the French Dewoitine D.27, when it achieved first place at an international air competition held in Bucharest, Romania.

[6] The Polish War Ministry objected to the aircraft's use of the licence-built Hispano-Suiza engine, citing insufficient practicality and poor economic grounds.

First reaching fighter squadrons during late 1935, it featured the adoption of a new, refined fuselage, a major change of which being the relocation of the engine to be 13 cm lower down in the aircraft's nose, which had the advantage of providing the pilot with an improved exterior view.

When it became apparent that the PZL.50 would not be in widespread service in time for a major conflict that was clearly looming, consideration was given to producing an updated version of the P.11; this was to have been powered by the 840 hp (626 kW) Mercury VIII and have been furnished with an enclosed cockpit, known as the P.11g Kobuz (hobby).

In 1939, after receiving the necessary credits, Poland ordered from France 120 Morane-Saulnier M.S.406s, and from Britain, 14 Hawker Hurricane Is (the P.11's chosen replacement), plus a single Supermarine Spitfire I for testing, in addition to 100 Fairey Battle light bombers.

[16] Instrumentation included navigation and engine gauges; while many of these components originated within Poland, one notable exception was the German-built compass.

Only a few P.11s were equipped with radio sets, leading to pilots typically being reliant upon hand signals and pre-arranged manoeuvres to communicate with one another.

The undercarriage had V-shape streamlined struts, furnished with Avia-type oleo pneumatic shock absorbers (including the tail skid) and were braced with steel wire.

[10] Originally manufactured by an independent sub-contractor, the tanks were rivetted and covered with a resin sealing agent; however, this technique resulted in joints that rapidly degraded in the presence of vibration.

An initial effort to switch to welded joints was catastrophic, having been determined to have been responsible for failures early on in the P.11's service life.

[10] Following a decision by some customers to refuse acceptance of completed aircraft using this type of joint due to these failures, extensive testing to evaluate alternative techniques was conducted by PZL, resulting in the problem being entirely eliminated.

[1][12] By 1 September 1939, the fighter squadrons had been deployed to remote improvised airfields and were therefore protected from German air attack on the ground.

In addition, their small total number meant that missions of groups larger than twenty aircraft were rarely undertaken, and reserve machines were almost non-existent.

[1] On the other hand, the Polish fighter aircraft featured better maneuverability than their German counterparts and, as a benefit of their design, much better vision from the cockpit.

[21] Attacking head on, the Polish pilots managed to shoot down seven twin-engined bombers, two of them credited to Lieutenant Stanisław Skalski (future Distinguished Flying Cross & Two Bars) for no losses to themselves.

Due to their obsolescence, these veteran aircraft were not used in combat; only a small number were used for training while the rest were dismantled for spare parts.