View source for PZL P.7

{{Short description|Polish fighter aircraft}}
{{Infobox aircraft
| name = PZL P.7
| image = PZL P7.jpg
| caption = PZL P.7
| type = [[fighter aircraft|Fighter]]
| manufacturer = [[Państwowe Zakłady Lotnicze|PZL]]
| first_flight = October 1930
| introduction = 1933
| retired = 
| produced = 1932–1933
| number_built = 149+2
| status = retired
| primary_user = [[Poland]]
| developed_from = [[PZL P.6]]
| variants = 
}}
The '''PZL{{nbsp}}P.7''' was a Polish [[gull wing]] monoplane [[fighter aircraft]] designed in the early 1930s at the [[Państwowe Zakłady Lotnicze|PZL]] factory in [[Warsaw]]. It was the main fighter of the [[Polish Air Force]] between 1933 and 1935. The PZL{{nbsp}}P.7 was replaced in Polish service by its follow-up design, the [[PZL P.11c|PZL{{nbsp}}P.11c]]. More than 30 PZL{{nbsp}}P.7 fighters remained in service during the [[Invasion of Poland]], scoring several kills despite its obsolescence.
{{TOC limit|limit=2}}

==Design and development==
The history of the PZL P.7 began in 1928, when a talented designer named [[Zygmunt Puławski]] designed an all-metal, metal-covered monoplane fighter, the [[PZL P.1]]. It introduced a high gull wing whose design was called the "Polish wing" or "Pulawski wing." The P.1 was powered by an [[inline engine (aviation)|inline engine]] and developed a speed of {{cvt|302|km/h}}. But it remained a prototype because a decision was made to use a licence-produced [[radial engine]] in the Polish Air Force fighters. So the next model, the [[PZL P.6]], flown in August 1930, was powered by the [[Bristol Jupiter]] VI FH radial engine. Both aircraft were well received and it won the American [[National Air Races]] in August–September 1931.

The PZL P.6 did not enter production because a more advanced variant, the '''PZL P.7''', was in development. The first prototype was basically a P.6 with a more powerful Bristol Jupiter VII.F engine. The addition of a [[supercharger]] improved performance at higher altitudes. The prototype P.7/I was first flown in October 1930 by [[Bolesław Orliński]].<ref name=morgala/> Initially, engine cylinders had individual cylinder fairings. After numerous changes, most noticeably the addition of a wide [[Townend ring]] to the engine, and a higher aspect tail, the second prototype P.7/II which had been completed in autumn 1931, was accepted for production with the designation '''P.7a'''. The wing was redesigned with slightly increased span, taken from the [[PZL P.8]], and shorter [[aileron]]s were used, and structural changes eliminated external ribs from the wing upper surfaces.<ref name=morgala/> P.7a production began in mid-1932 and the last of the 149 (plus two prototypes) were completed in 1933.<ref name=morgala>Morgała, Andrzej (2003): ''Samoloty wojskowe w Polsce 1924–1939''. Warszawa: Bellona. {{ISBN|8311093199}}, pp. 48–54 (in Polish)</ref> The [[Polish Air Force]] received the P.7a in 1933.

Puławski continued to develop the basic design by adding more powerful engines, which resulted in the '''[[PZL P.11]]'''. Puławski preferred inline engines and also designed the slimmer '''[[PZL P.8|P.8]]''' and the related P.9 with inline engines but he died in an air accident in March 1931, and these were cancelled. The P.11 became the standard Polish fighter while the '''[[PZL P.24]]''' was developed in parallel as an export variant in 1932.

===Technical features===
The all-metal, [[duralumin]] metal-covered strut braced gull-wing [[monoplane]] was conventional in layout, and used a conventional fixed undercarriage with a tail skid. The two-spar trapezoid wing was thinner by the fuselage and was covered with a ribbed Wibault type duralumin sheet (although the upper surfaces were smooth) and braced by two struts on each side. The fuselage was framed in a front section and semi-[[monocoque]] in mid- and tail sections, oval in cross-section. In keeping with the period, the pilot's cockpit was open with a windshield. Armament was two {{cvt|7.92|mm|3}} machine guns mounted on the fuselage sides which replaced the initially fitted {{cvt|7.7|mm|3}} Vickers E which were re-bored. The aircraft was powered by a {{cvt|360|to|390|kW}} [[Bristol Jupiter]] VII F radial engine fitted with a [[Townend ring]] and two-blade propeller. A main {{cvt|290|L}} fuel tank in the fuselage, behind the engine could be dropped in case of a fire emergency. The second fuel tank was {{cvt|7|L}}.

==Operational history==
The PZL P.7a entered service in spring 1933, replacing PWS-A (a licence-built [[Avia BH-33]]) and [[PWS-10]] fighters. Consequently, the [[Polish Air Force]] became the first air force entirely equipped with all-metal monococque fighters.<ref name=morgala/><ref>Murphy and McNiece 2009, [https://books.google.com/books?id=PW8kvG9wzTcC&pg=PA18 pp. 18–19.]</ref> When the P.7 entered service, it was comparable to contemporary designs, but due to rapid progress, it was obsolete by 1939. From 1935, the [[PZL P.11]] replaced the P.7 in most combat units, but was only a slight improvement, while the P.7as were relegated to air schools.

At the outbreak of [[World War II]] on 1 September 1939, the Polish Air Force still had 30 PZL P.7a fighters in combat units. A further 40 were with flying schools, and 35 were in reserve or undergoing repairs for a total of 106 aircraft. The P.7as were used by three squadrons, each equipped with 10 aircraft. The [[Pursuit Brigade]]'s [[Polish 123rd Fighter Escadrille|123rd Squadron]] was deployed near [[Warsaw]], while the [[Polish 151st Fighter Escadrille|151st]] and the [[Polish 162nd Fighter Escadrille|162nd Squadron]]s were attached to Army units. Despite being obsolete, they engaged the German attackers during the [[invasion of Poland]]. In addition to combat units, at least 18 P.7a fighters were used by improvised units from air bases in [[Dęblin]] and Ułęż.

Although the P.7 was more manoeuvrable than their opponents and could operate from short or rough fields, almost all the German aircraft were faster, and worse, the Polish aircraft and their engines were worn out from intensive service use. Their two machine guns was also inadequate and jammed frequently while only some replaced the vintage Vickers with the better {{ill|Karabin maszynowy wz. 33|lt=PWU FK wz.33|pl}}.<ref name=morgala/> Pilots flying the P.7a claimed to have shot down seven German aircraft (two [[Heinkel He 111]]s, two [[Dornier Do 17]]s, one [[Henschel Hs 126]] and two [[Messerschmitt Bf 110]]s), against 22 losses.

Most were destroyed in 1939, in combat or on the ground, but around a dozen were withdrawn to [[Romania]], but were not used in combat there. Some captured P.7s were used by the Germans for training. Several aircraft were captured by the Soviets and were also assigned to training units.

==Variants==
;P.6: precursor design prototypes with lower rated engine; two built.<ref name=Cynk/>
;P.7/I
:First prototype.
;P.7/II
:Second prototype equipped with [[Townend ring]].
;P.7a
:Serial-built version.

==Operators==
;{{flag|Germany|Nazi}}
*[[Luftwaffe]] operated few captured aircraft for training.
;{{POL}}
*[[Polish Air Force]]
;{{flagcountry|Kingdom of Romania}}
*[[Royal Romanian Air Force]] operated few interned aircraft for training.
;{{USSR}}
*[[Soviet Air Force]] operated few captured aircraft for training.<ref>Kotelnikov, Vladimir. "Lotnictwo w wojnie polsko-sowieckiej we wrześniu 1939 r.(in Polish)" ''Lotnictwo Wojskowe'',  May 1999.</ref>

==Specifications (PZL P.7a)==
{{Aircraft specs
|ref=Polish Aircraft 1893–1939<ref name=Cynk>{{cite book |last=Cynk |first=Jerzy B. |title=Polish Aircraft 1893–1939 |year=1971 |publisher=Putnam |location=London |isbn=978-0-370-00085-5 |url=https://archive.org/details/polishaircraft1800cynk/page/147 |pages=[https://archive.org/details/polishaircraft1800cynk/page/147 147-154] }}</ref>
|prime units?=met
|crew=One
|length m=7.16|span m=10.3|height m=2.75
|wing area sqm=17.2
|airfoil='''root:''' IAW-72 (Bartel 37/IIa) (6.5%); '''tip:''' IAW-72 (Bartel 37/IIa (8%))<ref name="Selig">{{cite web |last1=Lednicer |first1=David |title=The Incomplete Guide to Airfoil Usage |url=https://m-selig.ae.illinois.edu/ads/aircraft.html |website=m-selig.ae.illinois.edu |access-date=16 April 2019}}</ref>
|empty weight kg=1010|gross weight kg=1409
|fuel capacity={{cvt|250|L}} in a jettisonable fuselage tank
<!--Powerplant-->
|eng1 number=1|eng1 name=[[Polish Skoda Works Jupiter VIIF]]|eng1 type=9-cylinder air-cooled radial piston engine|eng1 hp=527
|eng1 note=for take-off
::{{cvt|485|hp|order=flip}} normal rating

|prop blade number=2|prop name=Szomański fixed-pitch wooden propeller|prop dia m=
<!--Performance-->
|max speed kmh=317|max speed note=at {{cvt|4000|m}}
::{{cvt|308|km/h}} at {{cvt|2000|m}}
::{{cvt|276|km/h}} at sea level
|stall speed kmh=102
|range km=560
|ceiling m=8275
|time to altitude={{cvt|1000|m}} in 1 minute 38 seconds
::{{cvt|3000|m}} in 5 minute 3 seconds
|wing loading kg/m2=81.8
|power/mass={{cvt|0.1613|hp/lb|order=flip}}
<!--Armament-->
|guns= 2 x {{cvt|7.9|mm}} [[Vickers Model E machine gun]]s (later series: [[Karabin maszynowy wz. 33]] machine guns)
}}

==See also==
{{aircontent
|related=
*[[PZL P.6]]
*[[PZL P.8]]
*[[PZL P.11]]
*[[PZL P.24]]
|similar aircraft=
*[[Dewoitine D.371]]
*[[Loire 46]]
*[[Ikarus IK-2]]
|lists=
}}

==References==
{{Commons category|PZL P.7}}

===Notes===
{{Reflist}}

===Bibliography===
* Cynk, Jerzy B. ''History of the Polish Air Force 1918–1968''. Reading, Berkshire, UK: Osprey Publishing Ltd., 1972.
* Cynk, Jerzy B. ''Polish Aircraft, 1893–1939''. London: Putnam & Company Ltd., 1971. {{ISBN|0-370-00085-4}}.
* Eberspacher, Warren A. and Jan P. Koniarek. ''PZL Fighters Part One - P.1 through P.8. (International Squadron Monograph 2)''. St. Paul, MN: Phalanx Publishing Co., Ltd., 1995. {{ISBN|1-883809-12-6}}.
* Glass, Andrzej. ''Polskie konstrukcje lotnicze 1893–1939'' (in Polish: "Polish aviation constructions 1893–1939"). Warszawa, Poland: WKiŁ, 1977. no ISBN.
* Glass, Andrzej. ''PZL P.7: Cz.1''. Gdańsk, Poland: AJ Press, 2000. {{ISBN|83-7237-080-X}}.
* Kopański, Tomasz J. ''PZL P.7: Cz.2''. Gdańsk, Poland: AJ Press, 2001. {{ISBN|83-7237-081-8}}.
* Murphy, Justin D. and Matthew A. McNiece. ''Military Aircraft, 1919–1945: An Illustrated History of their Impact.'' Santa Barbara, California: ABC-CLIO, 2009. {{ISBN|1-85109-498-9}}.

{{PZL aircraft}}
{{Authority control}}

{{DEFAULTSORT:Pzl P.7}}
[[Category:Gull-wing aircraft]]
[[Category:1930s Polish fighter aircraft]]
[[Category:PZL aircraft]]
[[Category:Single-engined tractor aircraft]]
[[Category:Aircraft first flown in 1930]]
[[Category:Aircraft with fixed conventional landing gear]]