View source for PZL P.11

{{Short description|Fighter aircraft in Poland}}
{{Infobox aircraft
| name = PZL P.11
| image = File:PZL P.11c '39 - 2' (14336386246).jpg
| caption = The sole surviving P.11 on display in the Polish Aviation Museum
| type = [[fighter aircraft|Fighter]]
| manufacturer = [[Państwowe Zakłady Lotnicze]] <br> [[Industria Aeronautică Română]]
| designer = [[Zygmunt Pulawski]]
| first_flight = August 1931<ref name="Cynk">{{cite book |last=Cynk |first=Jerzy B. |title=Polish Aircraft 1893-1939 |url=https://archive.org/details/polishaircraft1800cynk |url-access=registration |publisher=Putnam & Company Ltd. |location=London |year=1971 |edition=1st |pages=[https://archive.org/details/polishaircraft1800cynk/page/158 158–172] |isbn=0-370-00103-6}}</ref>
| introduction = 1934
| retired = 1944
| number_built = 325<ref name="Cynk"/>
| status = 
| unit cost = 
| primary_user = [[Polish Air Force]]
| more_users = [[Royal Romanian Air Force]]
| developed_into = [[PZL P.24]]
}}

The '''PZL P.11''' is a Polish fighter aircraft, designed and produced in the early 1930s by [[Państwowe Zakłady Lotnicze]]. 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.<ref name="Cynk"/>

Work on the PZL P.11 began in the 1930, based on experience with previous aircraft from the family of fighters derived from the [[PZL P.1]]. The primary individual responsible for their development was Polish [[Aerospace engineering|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 [[Biplane|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. In August 1931, the first prototype conducted its [[maiden flight]]. The design quickly drew international attention; the general layout became commonly known as the "[[Gull wing|Polish wing]]" or "Puławski wing".

The PZL P.11 served as the basic fighter of the [[Polish Air Force|Polish Military Aviation]] in the second half of the 1930s, including during the [[Invasion of Poland|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.<ref name="Cynk"/> Many fighter squadrons took up an unequal fight, achieving some successes. It is estimated that as many as 36 P.11s were evacuated to Romania and were subsequently taken over by the [[Royal Romanian Air Force]].

In the early 1930s, the PZL P.11 won a contract for a new fighter aircraft for the Royal Romanian Air Force. During October 1933, deliveries of Polish-built P.11b to Romania commenced.<ref name="AE28 p43"/> From 1936, Romanian aircraft manufacturer [[Industria Aeronautică Română]] (IAR) license-built a further 95 aircraft under the designation '''IAR P.11f''', powered by the Romanian-built IAR 9Krse engines.<ref name=morg63/> A more advanced development of the PZL P.11, which achieved much greater export success, was the [[PZL P.24]]. In the mid-1930s, several countries expressed their willingness to purchase the PZL P.11, of which Turkey, Bulgaria and Greece decided to acquire the new PZL P.24 instead.<ref name="Cynk"/><ref name="Winchester p. 219"/>

==Development==
===Origins===
The history of the PZL P.11 started in 1929, when Polish [[Aerospace engineering|aeronautical engineer]] [[Zygmunt Puławski]] began work on the design of an all-metal,  [[monoplane]] fighter aircraft. Before this, the Polish aviation industry had concentrated on the [[licensed production]] of foreign-designed aircraft, particularly French; these typically had wooden structures, so Puławski's all-metal approach represented a considerable advance for Polish industry.<ref name = "liss 3">Liss 1970, p. 3.</ref>

The initial design produced by Puławski, designated the '''P.1''', had many of the features of contemporary French aircraft of the era; these similarities can be attributed to Puławski himself, who had received a considerable portion of his technical education in France only a few years before. Nevertheless, the P.1 also had a number of original features, including its characteristic monoplane wing design.<ref name = "liss 3"/> 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.<ref name = "liss 3 4"/>

During September 1929, the first prototype made its [[maiden flight]].<ref name = "liss 4">Liss 1970, p. 4.</ref> 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. The design generated interest around the world; attention was such that the general layout became commonly known as the "Polish wing" or "Puławski wing". This wing had a two-spar [[duralumin]] structure, with [[rivet]]ted ribs to both the spars and skin; the exterior of the wing was covered by finely corrugated duralumin sheet, while the slotted ailerons had a [[fabric]] covering.<ref name = "liss 3 4">Liss 1970, pp. 3-4.</ref>

The Polish War Ministry objected to the aircraft's use of the licence-built [[Hispano-Suiza]] engine, citing insufficient practicality and poor economic grounds.<ref name = "liss 4"/> Accordingly, a second prototype, which was designated as the '''P.6''', was completed the next year. This revision featured several deviations from Puławski's original vision, including the adoption of a [[radial engine]] to power the type in place of the original in-line counterpart; during testing, the P.6's engine was plagued by overheating issues.<ref name = "liss 3 4"/>

===Refinement and production===
Following the disappointing performance of the P.6, a further improved design, designated as the [[PZL P.7]], was developed. According to Liss, this revision represented the most significant of the P.11's forerunners.<ref name = "liss 4"/> The P.7 was placed into series production, having been ordered for the [[Polish Air Force]], who ultimately opted to procure 150 of the type.<ref name="Cynk"/>

After designing the P.7, Puławski started further variants with larger engines, eventually cumulating in the P.11.<ref name = "liss 4"/> During August 1931, the first '''P.11/I''' prototype conducted its [[maiden flight]], powered by the British [[Bristol Jupiter]] radial engine; the first flight had occurred shortly after Puławski's death in an air crash.<ref name = "liss 4"/> It was followed by a pair of refined prototypes, the '''P.11/II''' and the '''P.11/III''', which used the [[Bristol Mercury]] engine instead. They were later joined by several more pre-production aircraft to test out various configurations of engines, propellers, and other features; these test examples led to the '''P.11/VI''', a production-representative version of the design.<ref name = "liss 4 5">Liss 1970, pp. 4-5.</ref>

The first variant of the P.11 to be ordered by the Polish Air Force was the '''P.11a'''. From the onset, this was considered to be only an interim model of the type; accordingly, a series of 50 such fighters were constructed.<ref name=morg60>Morgała 1997, p.60-61</ref> Otherwise similar to the P.7, the P.11a mounted the 575&nbsp;hp (429&nbsp;kW) Bristol Mercury IV S2 radial engine, which was produced in Poland under licence.<ref name="Cynk"/> Upon the completion of the P.11a order, PZL immediately set about establishing the production of an improved model of the aircraft, which was designated as the '''P.11c'''.<ref name = "liss 5"/>

The P.11c would be the principal (and final) variant of the type to be inducted into the Polish Air Force. 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&nbsp;cm lower down in the aircraft's nose, which had the advantage of providing the pilot with an improved exterior view.<ref name = "liss 5"/> Besides, a new stronger engine Mercury V S2 had smaller diameter. Forward framework was longer, covering an enlarged and more comfortable cockpit, with pilot's seat moved 30&nbsp;cm rearwards and raised by 5&nbsp;cm.<ref name=morg60/> The central part of the wings was also modified. During 1934, production of the P.11c commenced, by 1936, the type was being produced at a rate of 25 fighters per month; in total, 150 aircraft were produced by the end of production in 1936 (older sources quoted a number of 175, which is not confirmed in any documents).<ref name=morg60/> The first series of approximately 50 P.11c aircraft were fitted with Mercury V S2 of 600&nbsp;hp (447&nbsp;kW), the rest with Mercury VI S2 of 630&nbsp;hp (470&nbsp;kW).<ref name="Cynk"/>

Apart from Poland, Romania showed interest in the new design. Even before the P.11a entered service with the Polish Air Force, 50 aircraft, designated as the '''P.11b''', were ordered for the [[Romanian Air Force]], while an agreement for licence production was agreed.<ref name = "liss 5">Liss 1970, p. 5.</ref> Deliveries of Polish-built P.11bs to Romania commenced in July 1934.<ref>Mazur 2013, p.13-14</ref> They were fitted with [[Gnome-Rhone 9K]]rsd ''Mistral'' {{convert|595|HP|abbr=on}} engines, otherwise they were similar to the P.11a.<ref name="AE28 p43">Green and Swanborough 1985, p. 43.</ref> 49 were finally made, the 50th aircraft being P.11f prototype.<ref name=morg60/> After the P.11c had been developed, the Romanians decided to switch the licence production to the new model. As a result, from 1936 [[Industria Aeronautică Română|IAR]] built 95 aircraft as the '''IAR P.11f''', powered by the Romanian-built IAR 9Krse engine, which was a licensed version of the Gnome-Rhone 9Krse giving {{convert|610|hp|abbr=on}}.<ref name=morg63>Morgała 1997, p. 63, 69</ref> The Romanians then produced another Polish fighter, the [[PZL P.24]], developed from the P.11 exclusively for export. Greece, Portugal, Yugoslavia, Turkey and Republican Spain were interested in buying the P.11, but finally Bulgaria, Greece and Turkey bought the P.24 instead.<ref name="Cynk"/><ref name="Winchester p. 219"/>

===Further development and successors===
During 1934, the year in which the P.11 entered operational service, it was a contemporary of the British [[Gloster Gauntlet]] and German [[Heinkel He 51]] and was arguably the most advanced fighter then in service in the world.<ref name="Winchester p. 219">Winchester 2004, p. 219.</ref> However, due to a series of rapid advances and technological development in the field of aviation, the P.11 was considered to have been rendered obsolete by 1939. It had been overtaken in terms of performance by a new generation of fighter aircraft that commonly benefitted from features such as [[cantilever]] wings and retractable [[landing gear]]; such fighters included the British [[Supermarine Spitfire]] and German [[Messerschmitt Bf 109]].<ref name="Symanowski and Hoffmann p. 1">Symanowski and Hoffmann 2006, p. 1.</ref>

Together with the older P.7, both remained the only Polish fighters in service, however, with about 185 P.11s available, distributed within six air regiments and the aviation school in Dęblin. Being aware that the P.11 was now outdated, the Polish Air Force had pinned their hopes on the in-development [[PZL.50 Jastrząb]], which suffered from several delays. 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&nbsp;hp (626&nbsp;kW) Mercury VIII and have been furnished with an enclosed cockpit, known as the '''P.11g Kobuz''' (''[[Eurasian hobby|hobby]]''). Only the prototype of the P.11g with a maximum speed increase to a still-slow 390&nbsp;km/h (~240&nbsp;mph) was flown before the war, in August 1939.<ref name="Cynk"/><ref name = "liss 6">Liss 1970, p. 6.</ref>

In light of the unavailability of PZL.50, the only hope of replacing the obsolete P.11 lay in acquiring modern fighters from abroad. In 1939, after receiving the necessary credits, Poland ordered from France 120 [[Morane-Saulnier M.S.406]]s, and from Britain, 14 [[Hawker Hurricane|Hawker Hurricane I]]s (the P.11's chosen replacement), plus a single [[Supermarine Spitfire|Supermarine Spitfire I]] for testing, in addition to 100 [[Fairey Battle]] light bombers.<ref>[http://www.century-of-flight.net/Aviation%20history/WW2/Polish%20Air%20Force.htm "Polish Air Force."] {{Webarchive|url=https://web.archive.org/web/20160304115635/http://www.century-of-flight.net/Aviation%20history/WW2/Polish%20Air%20Force.htm |date=2016-03-04 }} ''century-of-flight.net,'' 2003. Retrieved: 7 July 2011.</ref><ref name = "liss 6"/> However, none of these aircraft were delivered to Poland before September 1939.<ref name="Cynk"/>

==Design==
The PZL P.11 was an innovative fighter aircraft for the early 1930s, with a high-mounted [[gull wing]] and an all-metal, metal-covered structure. It also had several relatively conventional features for the era, such as a fixed [[landing gear|undercarriage]].<ref name = "liss 6 7"/> The P.11 was equipped with a pair of 7.92&nbsp;mm machine guns mounted on the sides of the fuselage; reportedly, around a third of all P.11c-model fighters were fitted with two additional machine guns fixed onto the wings.<ref name = "liss 6 7"/> The fuselage-mounted guns were synchronised, but all others were not; a [[gun camera]] could also be installed.The P.11c could carry up to four small 12.5&nbsp;kg bombs, while the earlier P.11a model was not equipped to carry any.<ref name = "liss 6 7">Liss 1970, pp. 6-7.</ref>

The P.11 was powered by a number of different [[radial engine]]s: these included the [[Bristol Mercury|Bristol Mercury IV S2]] (normal: {{convert|525|hp|abbr=on}}, maximum: 575&nbsp;hp) of the '''P.11a''', the Gnome-Rhone 9Krsd (550&nbsp;hp, max: 595&nbsp;hp) of the '''P.11b''', the Bristol Mercury V S2 (565&nbsp;hp, max: 600&nbsp;hp) or alternatively the Mercury VI S2 (590&nbsp;hp, max: 630&nbsp;hp) of the '''P.11c''': and finally the Gnome-Rhone 9Krse (560&nbsp;hp, max: 610&nbsp;hp) of the '''P.11f''', the ultimate version of the aircraft.<ref name="Cynk"/> Regardless of the engine used, the unit was mounted upon [[rubber]] vibration absorbers inside a forward-mounted engine bay and drove a wooden two-bladed [[Propeller#Propeller theory|fixed-pitch propeller]] manufactured by Polish company [[Szomanski]].<ref name = "liss 6"/>

The P.11 had an open cockpit, with a [[Plexiglas]] windshield.<ref name = "liss 7"/> Instrumentation included  navigation and engine  gauges; while many of these components originated within Poland, one notable exception was the German-built [[compass]]. The safety equipment included an arrangement of several [[fire damper|flame damper]]s, a [[flare gun]], and oxygen tanks for the pilot. 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.<ref name = "liss 7">Liss 1970, p. 7.</ref>

The all-metal fuselage of the P.11 was matched to the twin-spar shoulder-mounted wing  via bearers mounted on the upper portion of the first and second fuselage frames.<ref name = "liss 6"/> The wing and the tail used similar construction techniques, making use of Daude-type rivets, a corrugated duralumin sheet exterior and solid duralumin struts and plates for strengthening. The undercarriage had V-shape [[streamlined]] struts, furnished with Avia-type oleo [[pneumatic]] [[shock absorber]]s (including the tail skid) and were braced with steel wire.<ref name = "liss 6"/>

The P.11 had an internal fuel tank inside the fuselage which could be jettisoned in case of fire or other emergency.<ref name = "liss 6"/> A high-profile flaw was present in the construction of early examples in the form of its fuel tanks.<ref name = "liss 5"/> 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 [[welding|welded]] joints was catastrophic, having been determined to have been responsible for failures early on in the P.11's service life.<ref name = "liss 5"/> 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.<ref name = "liss 5 6">Liss 1970, pp. 5-6.</ref>

==Operational history==
[[File:Samoloty PZL P.11a 1939.jpg|thumb|left|PZL P.11a aircraft]]
At the outbreak of the [[World War II|Second World War]], on 1 September 1939, the [[Polish Air Force]] had 109 PZL P.11cs, 20 P.11as and 30 [[PZL P.7|P.7a]]s in combat units. A further 43 P.11c aircraft were in reserve or undergoing repairs. Only a third of P.11c were armed with four machine guns, the rest had only two, and even fewer had a radio. The P.11 were used in twelve [[escadrille]]s (''eskadra''), each with ten aircraft (two escadrilles constituted a squadron, in [[Polish language|Polish]]: ''dywizjon''). Two squadrons—four escadrilles—were in the Pursuit Brigade deployed around Warsaw, with the rest assigned to various armies.<ref name = "liss 9 10">Liss 1970, pp. 9-10.</ref> All of them took part in the [[Invasion of Poland|1939 defense of Poland]]. Apart from combat units, several P.11 aircraft, including a prototype P.11g, were used in improvised units at air bases.<ref name="Cynk"/><ref name="Symanowski and Hoffmann p. 1"/>

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. The P.11 would be up against more modern German bombers and fighters—not only were the German [[Messerschmitt Bf 109]] and [[Messerschmitt Bf 110|Bf 110]] faster and better armed, but most German ''bombers'' were also faster. Since the P.11 fighters had seen years of intensive use before the war, their maximum speed was even lower than the theoretical 375&nbsp;km/h. The P.11a's were in even worse condition. 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.<ref name="Cynk"/>

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. The P.11 also had a durable construction and a good rate of climb, and could take off from short airfields, even of the rough and improvised variety. It could also dive at up to 600&nbsp;km/h without risk of the wings breaking off. Theoretically the only limit in maneuvers was the pilot's ability to sustain high [[g-force|''g'' forces]]. Despite the German superiority, the 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. A total of 285 German aircraft were lost according to ''Luftwaffe'' records, with at least 110 victories credited to the P.11 for the loss of about 100 of their own.<ref>Hooton 2007 (Vol. 2), p. 43.</ref> Some of the German aircraft shot down were later recovered and put back into service. This allowed German propaganda to claim smaller combat losses.<ref name="Cynk"/>

At dawn on 1 September, Capt. Mieczysław Medwecki flying a PZL P.11c was shot down by ''[[:de:Rotte (Luftfahrt)|Rottenführer]]'' (Foreman Leader) ''[[Leutnant]]'' [[Frank Neubert]] of I./[[StG 2]] (Stuka), having the dubious honour of becoming the first aircraft shot down in the Second World War. The first Allied air victory, the shooting down of a [[Junkers Ju 87]], was achieved 20 minutes later by Medwecki's wingman, [[Władysław Gnyś]], who went on to shoot down a pair of [[Dornier Do 17]]s with his P.11c.<ref name = "liss 10">Liss 1970, p. 10.</ref> The P.11c was also the first aircraft to successfully [[Aerial ramming|ram]] an enemy aircraft in the Second World War. The first large air battle of the war took place in the early morning of 1 September over the village of [[Nieporęt]] just north of Warsaw, when a German bomber group of about seventy [[Heinkel He 111]] and [[Dornier Do 17]] was intercepted by some twenty P.11 and ten P.7 fighters, and had to abandon their mission to Warsaw.<ref name="Cynk"/>
The following day, nine PZL P.11s of No. 142 Squadron, led by Captain Mirosław Leśniewski, intercepted two formations of Dornier Do 17 on river [[Vistula]].<ref name="Jackson p. 27.">Jackson 1979, p. 27.</ref> 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 (United Kingdom)|Distinguished Flying Cross]] & [[Medal bar|Two Bars]]) for no losses to themselves.<ref name="Jackson pp. 28-29.">Jackson 1979, pp. 28-29.</ref>
Most of the P.11s were destroyed in 1939, though thirty-six were flown to Romania and taken over by the Romanian Air Force. 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. It has been alleged that some aircraft were captured and saw limited use by the Germans.<ref name = "liss 8">Liss 1970, p. 8.</ref> A pair of P.11s were captured by the [[Red Army]] and used for testing. One landed in [[Hungary]] (near the town of [[Hajdúböszörmény]]) and was used as a [[Glider (sailplane)|glider]] tow plane by the [[Budapest University of Technology|University of Technology]] in [[Budapest]].<ref name="Cynk"/>

==Variants==
;P.11/I
:First prototype of the P.11 fighter, powered by a {{convert|384|kW|hp|abbr=on|0}} [[Gnome-Rhône Jupiter IX ASb]].<ref name="Cynk"/>
;P.11/II
:Second prototype of the P.11 fighter, powered by a {{convert|395|kW|hp|abbr=on|0}} [[Bristol Mercury IV.A]] in a long chord cowling. Used for comparative tests of [[Letov Kbely]], [[Bristol]], [[Ratier]], [[Szomański]] and [[Chauvière]] fixed pitch wooden propellers, achieving a best speed of {{convert|346|km/h|mph|abbr=on|0}} at {{convert|4,000|m|ft|abbr=on|0}} with the Chauvière.<ref name="Cynk"/>
;P.11/III
:Production prototype of the P.11 fighter, powered by a [[Bristol Mercury]], with simplified structure to ease production.<ref name="Cynk"/>
;P.11a
:The initial version for the Lotnictwo Wojskowe ([[Polish Air Force]]), which ordered fifty,<ref name=morg60/> actually built after completion of the Romanian P.11b order, powered by {{convert|370.6|kW|hp|abbr=on|0}} – {{convert|385.5|kW|hp|abbr=on|0}} [[Polish Skoda Works Mercuty IV.S2|Polish Skoda Works Mercury IV.S2]] engines.<ref name="Cynk"/>
;P.11b
:Fifty aircraft ordered by the Romanian Government, powered by {{convert|391.5|kW|hp|abbr=on|0}} [[Gnome-Rhône 9K Mistral]] or [[I.A.R. 9K Mistral|IAR 9K Mistral]] engines.<ref name="Cynk"/> 49 were actually built.<ref name=morg60/>
;P.11c
:The main production version for Lotnictwo Wojskowe.<ref name="Cynk"/> 150 built.<ref name=morg60/>
;P.11f
:95 aircraft, powered by {{convert|449|kW|hp|abbr=on|0}} [[I.A.R. 9K Mistral|IAR 9K Mistral]] engines, built as licence production by [[Industria Aeronautică Română|IAR]] in [[Romania]].<ref name=morg63/>
;P.11g Kobuz
:Developed as a stop-gap to fill in for delayed [[PZL.50 Jastrząb]] fighters by strengthening the structure to absorb the power of a single {{convert|626.37|kW|hp|abbr=on|0}} [[P.Z.L. Mercury VIII|Mercury VIII]], with an enclosed cockpit and four improved {{convert|7.92|mm|in|abbr=on|3}} [[Karabin lotniczy uniwersalny wz. 36|km wz.&nbsp;36]] machine-guns.<ref name="WiliamsFGWWII">{{cite book|last=Williams|first=Anthony G.|author2=Dr Emmanuel Gustin |title=Flying Guns World War II, Development of aircraft guns, ammunition and installations 1933-45|location=Ramsbury|year=2003|edition=1st|isbn=978-1-84037-227-4}}</ref> The converted P.11c prototype flew for the first time on 15 August 1939, less than a month before the German invasion, forcing abandonment of the programme.<ref name="Cynk"/>

==Operators==
[[File:PZL P.11f.png|thumb|IAR-produced PZL P.11f]]
;{{flag|Hungary|1920}}
* [[Hungarian Air Force]] operated one ex-Polish Air Force PZL P.11a evacuated on 23 September 1939.
;{{LAT}}
* [[Latvian Air Force]] operated one ex-Polish Air Force PZL P.11a evacuated on 17 September 1939.<ref name="Belcarz">Belcarz and Kopański, 2003, p. 60.</ref>
;{{POL}}
* [[Polish Air Force]]
;{{flagcountry|Kingdom of Romania}}
* [[Royal Romanian Air Force]]
;{{USSR}}
* [[Soviet Air Force]] took over the Latvian machine when they invaded Latvia 17 June 1940, and two more (see above) as war prizes.<ref name="Belcarz"/>

==Surviving aircraft==
The sole surviving P.11c aircraft is on display in the [[Polish Aviation Museum]] in [[Kraków]].<ref>{{cite web |title=Aeroplane: PZL P.11c |url=http://muzeumlotnictwa.pl/zbiory_sz.php?ido=13&w=a |website=Polish Aviation Museum |access-date=8 March 2021}}</ref>

==Specifications (PZL P.11c with Mercury VI.S2 engine)==
[[File:PZL 11c.svg|thumb|PZL P.11c 3-view drawing]]
{{Aircraft specs
|ref=''Polish Aircraft 1893-1939'',<ref name="Cynk"/> ''and The PZL P.11''<ref name = "liss 12">Liss 1970, p. 12.</ref>
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** {{convert|5,000|m|ft|abbr=on}} in 6 minutes
** {{convert|7,000|m|ft|abbr=on}} in 13 minutes
|wing loading kg/m2=91.1
|wing loading lb/sqft=
|wing loading note=
|fuel consumption kg/km=
|fuel consumption lb/mi=
|power/mass=0.279 kW/kg (0.166 hp/lb)
|thrust/weight=
|more performance=
<!--
        Armament
-->
|guns=<br/>
** 2 x {{convert|7.92|mm|in|abbr=on|3}} [[wz. 33]] [[machine gun]]s in fuselage with 500 rpg.<ref name="WiliamsFGWWII"/>
** optionally additional 2 × {{convert|7.92|mm|in|abbr=on|3}} [[wz. 33]] [[machine gun]]s in wings with 300 rpg.<ref name="WiliamsFGWWII"/>
|bombs= 
|rockets= 
|missiles= 
|hardpoints=
|hardpoint capacity=
|hardpoint rockets=
|hardpoint missiles=
|hardpoint bombs=
|hardpoint other=
|avionics=
}}

==See also==
{{Aircontent
|related=
* [[PZL P.7]]
* [[PZL P.24]]
* [[IAR-80]]
* [[Historical PZL P.11c]], a homebuilt scale replica of the PZL P.11c

|similar aircraft=
* [[Aero A.102]]
* [[Dewoitine D.37]]
* [[Dewoitine D.560]]
* [[Ikarus IK-2]]
* [[Loire 43]]
* [[Morane-Saulnier M.S.225]]
* [[Nakajima Army Type 91 fighter]]
* [[Nieuport-Delage NiD-120]]

|lists=
* [[List of aircraft of World War II]]
}}

==References==

===Notes===
{{reflist|group=N}}

===Citations===
{{reflist}}

===Bibliography===
* Axworthy, Mark. ''Third Axis, Fourth Ally''. London: Arms and Armour, 1995. {{ISBN|1-85409-267-7}}.
* Belcarz, Bartłomiej and Tomasz J.Kopański. ''PZL P.11c''. Sandomierz, Poland/Redbourn, UK: Mushroom Model Publications, 2003. {{ISBN|83-917178-5-2}}.
* Belcarz, Bartłomiej, Artur Juszczak, Tomasz Makowski and Robert Pęczkowski. ''PZL P.11c, Modelmania 2'' (Polish/English). Gdańsk, Poland: AJ-Press, 1998. {{ISBN|83-86208-96-1}}.
* Cynk, Jerzy B. ''History of the Polish Air Force 1918-1968''. Reading, Berkshire, UK: Osprey Publishing Ltd., 1972. {{ISBN|0-85045-039-X}}.
* {{cite book|last=Cynk|first=Jerzy B.|title=Polish Aircraft 1893-1939|url=https://archive.org/details/polishaircraft1800cynk|url-access=registration|publisher=Putnam & Company Ltd.|location=London|year=1971|edition=1st|pages=[https://archive.org/details/polishaircraft1800cynk/page/158 158–172]|isbn=0-370-00103-6}}
* Eberspacher, Warren A. and Jan P. Koniarek. ''PZL Fighters Part Two - P.11 Variants (Historical Aircraft Digest 00-5)''. Austin, CO: Creative & Customized Support, 2001. No ISBN.
* Glass, Andrzej. ''Polskie konstrukcje lotnicze 1893-1939'' (in Polish: "Polish Aviation Constructions 1893-1939"). Warszawa, Poland: WKiŁ, 1977. No ISBN.
* Green, William. ''Warplanes of the Second World War, Volume Three: Fighters''. London: Macdonald & Co.(Publishers) Ltd., 1961. {{ISBN|0-356-01447-9}}.
* Green, William and Gordon Swanborough. "The Era of the Gulls: The Chronicles of the Pulawski Fighter Line". ''[[Air Enthusiast]]'', Twenty-eight, July–October 1985, pp.&nbsp;35–53, 80. ISSN 0143-5450.
* Hooton, E.R. ''Luftwaffe at War; Blitzkrieg in the West: 1939–1940, Volume 2''. London: Midland Publishing, 2007. {{ISBN|1-85780-272-1}}.
* Hooton, E.R. ''Luftwaffe at War: Gathering Storm 1933–1939, Volume 1''. London: Chevron/Ian Allan, 2007. {{ISBN|1-903223-71-7}}.
*{{cite journal |last1=Jurca|first1=Marcel|title=J'ai piloté le P.Z.L. P.11)|journal=Le Fana de l'Aviation |date=April 1976 |issue=77 |pages=25–26 |issn=0757-4169 |language=fr|trans-title=I Flew the P.Z.L. P.11}}
* Koniarek, Dr. Jan P. ''Polish Air Force 1939-1945''. Carrollton, TX: Squadron/Signal Publications, Inc., 1994. {{ISBN|0-89747-324-8}}.
* Liss, Witold. ''The P.Z.L. P.11''. Leatherhead, Windsor, UK: Profile Publications Ltd., 1970.
*{{cite book |last= Mazur|first=Wojciech|date=2013|title=PZL.11 |language=pl |location= Warsaw|publisher=Edipresse Polska|isbn=978-83-7769-556-2|series=Wielki Leksykon Uzbrojenia. Wrzesień 1939|volume=8}} 
*{{cite book |last= Morgała|first=Andrzej |date= 1997|title= Samoloty wojskowe w Polsce 1918-1924|trans-title= Military aircraft in Poland 1918-1924|language=pl |location= Warsaw|publisher=Lampart |isbn=83-86776-34-X }}
* Taylor, John W.R. "PZL P.11." ''Combat Aircraft of the World from 1909 to the present''. New York: G.P. Putnam's Sons, 1969. {{ISBN|0-425-03633-2}}.
* Symanowski Grzegorz and Jan Hoffmann. ''PZL P.11C.'' Lublin, Poland: Kagero Polen, 2006. {{ISBN|83-60445-06-0}}.
* Winchester, Jim. ''PZL P.11.'' Aircraft of World War II (The Aviation Factfile). Kent, UK: Grange Books plc, 2004. {{ISBN|1-84013-639-1}}.
* {{cite book|last=Williams|first=Anthony G.|author2=Dr Emmanuel Gustin |title=Flying Guns World War II, Development of aircraft guns, ammunition and installations 1933-45|location=Ramsbury|year=2003|edition=1st|isbn=978-1-84037-227-4}}

==External links==
{{Commons category|PZL P.11}}
* [https://web.archive.org/web/20110514001151/http://republika.pl/rola1/files/pzl11_start_run_01.mp3 Recorded sound of the Bristol Mercury VI engine] used in [[PZL P.11c]] (mp3 format)
* [http://aircraftwalkaround.hobbyvista.com/pzl11/pzl11.htm PZL P.11 "Walkaround" photos]

{{PZL aircraft}}
{{IAR aircraft}}

{{DEFAULTSORT:Pzl P.11}}
[[Category:1930s Polish fighter aircraft]]
[[Category:Gull-wing aircraft]]
[[Category:PZL aircraft]]
[[Category:Single-engined tractor aircraft]]
[[Category:Aircraft first flown in 1931]]
[[Category:Aircraft with fixed conventional landing gear]]