The PZL P.24 was a Polish
fighter aircraft, designed during the mid-1930s in the
PZL
PZL (''Państwowe Zakłady Lotnicze'' - State Aviation Works) was the main Polish aerospace manufacturer of the interwar period, and a brand of their aircraft. Based in Warsaw between 1928 and 1939, PZL introduced a variety of well-regarded air ...
factory in
Warsaw
Warsaw ( pl, Warszawa, ), officially the Capital City of Warsaw,, abbreviation: ''m.st. Warszawa'' is the capital and largest city of Poland. The metropolis stands on the River Vistula in east-central Poland, and its population is officia ...
. It was developed as a dedicated export version of the
PZL P.11
The PZL P.11 was a Polish fighter aircraft, designed and constructed during the early 1930s by Warsaw-based aircraft manufacturer PZL. Possessing an all-metal structure, metal-covering, and high-mounted gull wing, the type held the distinction of ...
, a
gull wing
The gull wing is an aircraft wing configuration, known also as ''Pulaski wings'', with a prominent bend in the wing inner section towards the wing root. Its name is derived from the seabirds which it resembles. Numerous aircraft have incorpora ...
all-metal fighter designed by Polish
aeronautical engineer
Aerospace engineering is the primary field of engineering concerned with the development of aircraft and spacecraft. It has two major and overlapping branches: aeronautical engineering and astronautical engineering. Avionics engineering is sim ...
Zygmunt Puławski
Zygmunt Puławski (October 24, 1901 – March 21, 1931) was a Polish aircraft designer and pilot. He invented a gull-wing aircraft design, also known as "Puławski wing" and designed a series of Polish PZL fighters.
He was born in Lublin. In ...
.
While the P.11 had been powered with a
license-built Licensed production is the production under license of technology developed elsewhere. The licensee provides the licensor of a specific product with legal production rights, technical information, process technology, and any other proprietary compo ...
Bristol Mercury radial engine
The radial engine is a reciprocating type internal combustion engine configuration in which the cylinders "radiate" outward from a central crankcase like the spokes of a wheel. It resembles a stylized star when viewed from the front, and is ...
, the terms of this license did not permit PZL to export the engine as well as placing restrictions upon any aircraft that were powered by it. The French engine manufacturer
Gnome-Rhône proposed the adoption of their
14K engine to PZL and offered to partially finance the development of a fighter using the engine, which would have no such export restrictions. Accordingly, during early 1932, PZL commenced work on a new derivative of the P.11, which became known as the P.24. The prototypes soon demonstrated favourable performance during testing; notably, the second P.24/II prototype, often referred to as the "Super P.24", established a new world speed record for a radial engine-powered fighter of 414 km/h. The initial production aircraft closely resembled the P.24/II configuration, albeit with some changes such as the adoption of an enclosed
cockpit.
First entering operational service during 1936, the P.24 was exported to multiple countries, including
Bulgaria
Bulgaria (; bg, България, Bǎlgariya), officially the Republic of Bulgaria,, ) is a country in Southeast Europe. It is situated on the eastern flank of the Balkans, and is bordered by Romania to the north, Serbia and North Macedo ...
,
Greece
Greece,, or , romanized: ', officially the Hellenic Republic, is a country in Southeast Europe. It is situated on the southern tip of the Balkans, and is located at the crossroads of Europe, Asia, and Africa. Greece shares land borders ...
,
Romania
Romania ( ; ro, România ) is a country located at the crossroads of Central, Eastern, and Southeastern Europe. It borders Bulgaria to the south, Ukraine to the north, Hungary to the west, Serbia to the southwest, Moldova to the east, and ...
, and
Turkey
Turkey ( tr, Türkiye ), officially the Republic of Türkiye ( tr, Türkiye Cumhuriyeti, links=no ), is a transcontinental country located mainly on the Anatolian Peninsula in Western Asia, with a small portion on the Balkan Peninsula in ...
. It was produced under licence by Romanian aviation firm
Industria Aeronautică Română
Industria Aeronautică Română (IAR) (now IAR S.A. Brașov) or Romanian Aeronautic Industry in English, is a Romanian aerospace manufacturer. It is based in Ghimbav, near Brașov, Romania.
IAR was founded in 1925 with the aid of the Romanian g ...
(IAR), who had also licence-produced the earlier P.11 as well. Reportedly, elements of the P.24, such as its tail section, were incorporated into a Romanian-designed monoplane fighter, the
IAR 80
The IAR 80 was a Romanian World War II low-wing monoplane, all-metal monocoque fighter and ground-attack aircraft. When it first flew, in 1939, it was comparable to contemporary designs being deployed by the airforces of the most advanced milita ...
. In Greece, the
Royal Hellenic Air Force
, colours =
, colours_label =
, march =
, mascot =
, anniversaries = 8 November
, equipment =
, equipment_label ...
(EVA) was the only air service in
Second World War
World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the vast majority of the world's countries—including all of the great powers—forming two opposi ...
to operate the P.24 as its primary fighter. However, wartime experience soon showed that, as a result of the rapid advances in aircraft design made during the late 1930s, the P.24 had become obsolete in comparison to newer fighters as early as 1940. Despite a relatively powerful engine and satisfactory armament, it could not stand up against some of the
Axis
An axis (plural ''axes'') is an imaginary line around which an object rotates or is symmetrical. Axis may also refer to:
Mathematics
* Axis of rotation: see rotation around a fixed axis
* Axis (mathematics), a designator for a Cartesian-coordinat ...
fighters, such as the
Macchi MC.200 and the
Fiat G.50
The Fiat G.50 ''Freccia'' ("Arrow") was a World War II Italian fighter aircraft developed and manufactured by aviation company Fiat. Upon entering service, the type became Italy’s first single-seat, all-metal monoplane that had an enclosed ...
. Just like the Greek fighters, by 1942, it had become clear that Romania's P.24s were unable to effectively challenge the fighters of the
VVS, and were relegated to training operations.
Development
Background
During the early 1930s, PZL had developed a series of innovative
gull wing
The gull wing is an aircraft wing configuration, known also as ''Pulaski wings'', with a prominent bend in the wing inner section towards the wing root. Its name is derived from the seabirds which it resembles. Numerous aircraft have incorpora ...
all-metal fighters, headed by Polish
aeronautical engineer
Aerospace engineering is the primary field of engineering concerned with the development of aircraft and spacecraft. It has two major and overlapping branches: aeronautical engineering and astronautical engineering. Avionics engineering is sim ...
Zygmunt Puławski
Zygmunt Puławski (October 24, 1901 – March 21, 1931) was a Polish aircraft designer and pilot. He invented a gull-wing aircraft design, also known as "Puławski wing" and designed a series of Polish PZL fighters.
He was born in Lublin. In ...
.
The
P.1, the
P.7, and the
P.11, each more refined than its preceding aircraft, were capable of outstanding performance for their time and were widely displayed at international exhibitions and competitive fly-offs, demonstrating their capabilities to the world.
The Polish monoplanes were subject to considerable international interest, leading to PZL's offices receiving a deluge of enquiries on the topic of prospective export sales. According to aviation author J.B. Cynk, by 1933, outward interest had been expressed by
Bulgaria
Bulgaria (; bg, България, Bǎlgariya), officially the Republic of Bulgaria,, ) is a country in Southeast Europe. It is situated on the eastern flank of the Balkans, and is bordered by Romania to the north, Serbia and North Macedo ...
,
Czechoslovakia
, rue, Чеськословеньско, , yi, טשעכאסלאוואקיי,
, common_name = Czechoslovakia
, life_span = 1918–19391945–1992
, p1 = Austria-Hungary
, image_p1 ...
,
France
France (), officially the French Republic ( ), is a country primarily located in Western Europe. It also comprises of overseas regions and territories in the Americas and the Atlantic, Pacific and Indian Oceans. Its metropolitan area ...
,
Greece
Greece,, or , romanized: ', officially the Hellenic Republic, is a country in Southeast Europe. It is situated on the southern tip of the Balkans, and is located at the crossroads of Europe, Asia, and Africa. Greece shares land borders ...
,
Hungary
Hungary ( hu, Magyarország ) is a landlocked country in Central Europe. Spanning of the Pannonian Basin, Carpathian Basin, it is bordered by Slovakia to the north, Ukraine to the northeast, Romania to the east and southeast, Serbia to the ...
,
Japan,
Portugal
Portugal, officially the Portuguese Republic ( pt, República Portuguesa, links=yes ), is a country whose mainland is located on the Iberian Peninsula of Southwestern Europe, and whose territory also includes the Atlantic archipelagos of ...
,
Romania
Romania ( ; ro, România ) is a country located at the crossroads of Central, Eastern, and Southeastern Europe. It borders Bulgaria to the south, Ukraine to the north, Hungary to the west, Serbia to the southwest, Moldova to the east, and ...
,
Sweden,
Turkey
Turkey ( tr, Türkiye ), officially the Republic of Türkiye ( tr, Türkiye Cumhuriyeti, links=no ), is a transcontinental country located mainly on the Anatolian Peninsula in Western Asia, with a small portion on the Balkan Peninsula in ...
and
Yugoslavia
Yugoslavia (; sh-Latn-Cyrl, separator=" / ", Jugoslavija, Југославија ; sl, Jugoslavija ; mk, Југославија ;; rup, Iugoslavia; hu, Jugoszlávia; rue, label=Pannonian Rusyn, Югославия, translit=Juhoslavija ...
.
[Cynk 1967, p. 3.]
In order for any export sales of the type to be successfully completed, PZL had to address two major obstacles.
Firstly, the company was only capable of producing so many aircraft in the space of a year; PZL did not have the internal resources to substantially expand its production capacity, nor was financing from the Polish government or other bodies viewed as being particularly forthcoming during this time. According to Cynk, tentative customers for the fighter were typically adverse to making large currency exchanges as part of their payments, instead, they would usually prefer to pay in terms of goods (such as raw resources and industrial products) or to pay in numerous installments.
Furthermore, Cynk claims that several deals which had been formed with PZL had fallen through or had been otherwise postponed due to difficulties encountered in agreeing acceptable terms of payment between the customer and the manufacturer.
Another issue was posed by the engine used by the P.11.
It was powered by a single
Bristol Mercury radial engine
The radial engine is a reciprocating type internal combustion engine configuration in which the cylinders "radiate" outward from a central crankcase like the spokes of a wheel. It resembles a stylized star when viewed from the front, and is ...
, which was produced in Poland under a
licensing agreement
A license (or licence) is an official permission or permit to do, use, or own something (as well as the document of that permission or permit).
A license is granted by a party (licensor) to another party (licensee) as an element of an agreeme ...
with the British
Bristol Aeroplane Company; however, the terms of the 10-year agreement had stipulated that none of the Polish-built engines could be exported. In addition, the licensing agreement had placed restrictions upon the sale of those aircraft which were powered by the Bristol engine; these export restrictions were present even if the engines were to be supplied by the customers rather than by PZL themselves.
Naturally, PZL was keen to eliminate or otherwise minimise any restrictions that were deterring export sales of their aircraft.
According to Cynk, the initiative to develop a dedicated export-focused derivative of the P.11 received a considerable boost during the early 1930s by a
French Air Force initiative to furnish itself with a large force of modern first-rate fighters.
While the majority of projects considered by French officials were indigenously-developed, the French Air Force was also evaluating various foreign fighters as potential candidates for being licence-produced in France; Cynk claims that the P.11 was at the top of their list. This attention may have contributed to the decision by French engine manufacturer
Gnome-Rhône to offer PZL a financial contribution of 150,000
franc
The franc is any of various units of currency. One franc is typically divided into 100 centimes. The name is said to derive from the Latin inscription ''francorum rex'' (King of the Franks) used on early French coins and until the 18th centu ...
s towards the development of an export-suitable P.11 derivative, as well as to provide the first prototype's engine for free and to sponsor the fighter for the French competition, all of which was conditional to the selection of their engine to power the type.
Project launch
In accordance with these converging interests, PZL decided to embark upon preliminary design work into the prospective development of a further evolved form of the P.11 that would be aimed specifically at the export market. The project, and the resulting design produced by it, soon received its own designation as the ''P.24''. The
Gnome-Rhône 14K, a powerful French radial engine, had quickly emerged as a strong candidate to power the tentative fighter; thus the engine company's offer of support was quickly accepted.
[Cynk 1967, pp. 3-4.] The project was headed by Wsiewolod Jakimiuk, who had assumed the position early on after the untimely death of Puławski on 21 March 1931. During February 1932, the P.24 proposal was submitted for internal approval; this was granted two months later.
During May 1933, the first ''P.24/I'' prototype, which was largely based on the P.11a and powered by a
Gnome-Rhône 14Kds engine, conducted its
maiden flight
The maiden flight, also known as first flight, of an aircraft is the first occasion on which it leaves the ground under its own power. The same term is also used for the first launch of rockets.
The maiden flight of a new aircraft type is alw ...
, flown by
Bolesław Orliński
Bolesław Orliński (13 April 1899 – 28 February 1992) was a Polish aviator, military, sports and test pilot.
He was born on the family estate in Niwerka, Podolia (now Niverka, Kamianets-Podilskyi Raion, Khmelnytskyi Oblast, Ukraine). During W ...
.
This flight had been delayed since January 1933 due to a failure on the part of Gnome-Rhône to promptly deliver either the engine or its three-bladed metal propeller. Even following the installation of the engine and an alternative
Szomanski-built propeller, issues were encountered during pre-flight powered runs, such as seizing fuel pumps.
The maiden flight had not gone smoothly either; it had been cut short after severe vibrations had shattered the hub fairing, further damage to the propeller blades, engine bearing structure, and fuel tank attachments was also incurred, leading to the forward section of the prototype being reconstructed and reinforced. During October 1933, flight tests resumed.
[Cynk 1967, p. 4.]
The experiences with the first prototype had determined that in excess of 150 modifications to various aspects of the design, including the adoption of a long-chord
NACA
The National Advisory Committee for Aeronautics (NACA) was a United States federal agency founded on March 3, 1915, to undertake, promote, and institutionalize aeronautical research. On October 1, 1958, the agency was dissolved and its assets ...
cowling, the reinforcement of a
cannon
A cannon is a large- caliber gun classified as a type of artillery, which usually launches a projectile using explosive chemical propellant. Gunpowder ("black powder") was the primary propellant before the invention of smokeless powder ...
mounting structure and the revision of the exhaust and cooling systems, were required, leading to the construction of a second prototype, known as the ''P.24/II''.
Performing its first flight during March 1934, this prototype, also named the "Super P.24", quickly demonstrated its excellent performance, such as its ability to easily exceed 400 km/h in level flight. On 28 June 1934, P.24/II established a
Fédération Aéronautique Internationale-recognised world speed record for
radial engine
The radial engine is a reciprocating type internal combustion engine configuration in which the cylinders "radiate" outward from a central crankcase like the spokes of a wheel. It resembles a stylized star when viewed from the front, and is ...
-powered fighters of 414 km/h.
Following Gnome-Rhône's announcement of the existence of a more powerful 14Kfs engine, a third ''P.24/III'' prototype, otherwise known as the "Super P.24bis", was called for, powered by this new engine. However, this engine was not immediately available due to a prior order placed by
Finland
Finland ( fi, Suomi ; sv, Finland ), officially the Republic of Finland (; ), is a Nordic country in Northern Europe. It shares land borders with Sweden to the northwest, Norway to the north, and Russia to the east, with the Gulf of B ...
having taken precedence; as such, the first 14Kfs engine did not arrive until July 1934.
[Cynk 1967, pp. 4-5.]
During August 1934, the third prototype conducted its first flight; two months later, it performed a demonstration outside
Warsaw
Warsaw ( pl, Warszawa, ), officially the Capital City of Warsaw,, abbreviation: ''m.st. Warszawa'' is the capital and largest city of Poland. The metropolis stands on the River Vistula in east-central Poland, and its population is officia ...
attended by various Polish officials and several members of foreign missions.
During late 1934, the newly-completed P.24/III was publicly displayed at the
Paris Air Show
The Paris Air Show (french: Salon international de l'aéronautique et de l'espace de Paris-Le Bourget, Salon du Bourget) is a trade fair and air show held in odd years at Paris–Le Bourget Airport in north Paris, France. Organized by the French ...
, where it reportedly attracted a high level of interest from visitors and other participants alike. According to Cynk, at the time of the Paris Air Show, the P.24 was commonly considered to have been both the quickest and the best-armed interceptor in the world.
While the French Air Force were still expressing interest in the P.24 at this point, there was considerable political resistance to the procurement of it due to its non-indigenous origins and that French manufacturers were making their own advances, including some of those that were featured upon the P.24. As such, a French order was not forthcoming for the type.
[Cynk 1967, p. 5.]
Production
During late 1934 and early 1935, the P.24/III was involved in several promotional flights, including evaluation flights held near Warsaw on behalf of visiting Turkish and Romanian military officials, as well as a demonstration tour which saw it visit neighbouring
Hungary
Hungary ( hu, Magyarország ) is a landlocked country in Central Europe. Spanning of the Pannonian Basin, Carpathian Basin, it is bordered by Slovakia to the north, Ukraine to the northeast, Romania to the east and southeast, Serbia to the ...
and
Bulgaria
Bulgaria (; bg, България, Bǎlgariya), officially the Republic of Bulgaria,, ) is a country in Southeast Europe. It is situated on the eastern flank of the Balkans, and is bordered by Romania to the north, Serbia and North Macedo ...
.
In the spring of 1935, having judged the likelihood of sales to have been high at this point, PZL decided to commence work on a batch of six pre-production P.24s at their Warsaw plant. Unlike the prototypes, these aircraft had enclosed cockpits and the armaments were entirely carried within the wings rather than the forward fuselage, as well as the adoption of wing and tail surfaces reminiscent of the P.11c, alongside minor refinements and alterations.
Different armament arrangements were installed across the pre-production aircraft, representative to the configuration that was intended for several separate production models. One pre-production aircraft was shown at the 1936 Paris Air Show, after which it conducted several demonstration flights on behalf of the French Air Force.
[Cynk 1967, pp. 5-6.]
Gradually, the pre-production P.24s were modified to closely represent successive production variants of the type; this work included the installation of alternative engines, including the
Gnome-Rhône 14N01, the
Gnome-Rhône 14N21, the
Renault 14T, and the
Fiat A.80
The Fiat A.80 was an 18-cylinder, twin-row, air-cooled, radial aircraft engine produced during World War II. Rated at 1,000 hp (745 kW), it was a more powerful development of the 14-cylinder Fiat A.74.
Variants
;Fiat A.80 R.C.20:With ...
, which were freely provided by their respective manufacturers.
During early 1936, Turkey became the first customer to place a firm order for the P.24, completing a deal to not only by 40 Polish-built fighters, but also a licensing arrangement and the materials to domestically produce a further 20 P.24As. These early fighters, which were furnished with a range of different armaments to conform with the specified Turkish requirements, were otherwise nearly identical to the pre-production aircraft.
Production commenced almost immediately; the first deliveries took place during late 1936.
[Cynk 1967, p. 6.]
Following the encountering of greater-than-anticipated
drag on early production aircraft, various aerodynamic improvements were implemented upon the next variant of the fighter, designated as the P.24C, which made up the majority of the Turkish order.
On 29 May 1937, the first Turkish-built P.24 conducted its maiden flight, flown by Izfam Bay. According to Cynk, it is believed that in excess of 100 P.24s were ultimately constructed in Turkey at a peak rate of eight fighters being finished per month.
Over time, a large proportion of Turkey's P.24 fleet were reportedly refitted with American
Pratt & Whitney Twin Wasp
The Pratt & Whitney R-1830 Twin Wasp is an American air-cooled radial aircraft engine. It displaces and its bore and stroke are both . The design traces its history to 1929 experiments at Pratt & Whitney on twin-row designs. Production began ...
radial engines.
Further orders for the type soon came from Greece, Bulgaria, and Romania.
[Cynk 1967, pp. 6-7.] These aircraft featured various modifications, including increased endurance, customised armaments, and further aerodynamic improvements.
[Cynk 1967, p. 7.]
Despite being an objectively superior fighter to its P.11 predecessor, no P.24s were ever acquired by the Polish Air Force, which preferred to wait for the more advanced
PZL.50.
When it had become clear that the PZL.50 would not become available in time to counter the now-imminent German attack, figures within the Polish Air Force, such as General
Józef Zając
Józef Ludwik Zając (pron. Za-YANTz) (1891–1963) was a Polish general and pilot.
Biography
Born on 14 March 1891 in Rzeszów, Józef Zając studied at the Jagiellonian University in Kraków, graduating with a PhD in philosophy in 1915. He ...
, advocated an accelerated purchase of the type. In addition, the viability of such a venture was increased by the issuing of a French armament loan permitting a large quantity of 14K engines to be purchased by Poland.
During early 1939, an initial order for 70 P.24Hs was placed. This order was supplemented by orders for a variant of the older P.11, the P.11g, as well.
[Cynk 1967, pp. 7-8.] Despite numerous rumours claiming such, there were no PZL.24s in use by the Polish defenders during the
Polish Campaign
The invasion of Poland (1 September – 6 October 1939) was a joint attack on the Republic of Poland by Nazi Germany and the Soviet Union which marked the beginning of World War II. The German invasion began on 1 September 1939, one week afte ...
; these rumours may have been a result of the common misidentification of the P.11 as being the later P.24 by German spotters.
As late as 1939, further improvements of the P.24 were being studied.
The conceptual P.24K, which was to feature an armament of four 20mm cannon, and the P.24L, a dedicated fighter-bomber design, were amongst the proposals mooted. Furthermore, significant international interest in the type was present at this point.
According to Cynk, during 1939, negotiations for several large orders were either at an advanced stage or had been finalised; these customers had included
Estonia
Estonia, formally the Republic of Estonia, is a country by the Baltic Sea in Northern Europe. It is bordered to the north by the Gulf of Finland across from Finland, to the west by the sea across from Sweden, to the south by Latvia, a ...
,
Finland
Finland ( fi, Suomi ; sv, Finland ), officially the Republic of Finland (; ), is a Nordic country in Northern Europe. It shares land borders with Sweden to the northwest, Norway to the north, and Russia to the east, with the Gulf of B ...
, Greece, Hungary, and
Yugoslavia
Yugoslavia (; sh-Latn-Cyrl, separator=" / ", Jugoslavija, Југославија ; sl, Jugoslavija ; mk, Југославија ;; rup, Iugoslavia; hu, Jugoszlávia; rue, label=Pannonian Rusyn, Югославия, translit=Juhoslavija ...
. However, none of these orders, tentative or otherwise, totalling in excess of 190 P.24s, would be completed; they were effectively cancelled as a consequence of the German invasion and occupation of Poland during September 1939.
[Cynk 1967, p. 8.]
Design
The ''PZL P.24'' was a
gull wing
The gull wing is an aircraft wing configuration, known also as ''Pulaski wings'', with a prominent bend in the wing inner section towards the wing root. Its name is derived from the seabirds which it resembles. Numerous aircraft have incorpora ...
all-metal
fighter aircraft that drew extensively on the design of the earlier
P.11, being essentially a more powerful and export-friendly version of it.
It possessed a relatively conventional in layout, but incorporated more recent innovations such as its all-metal structure and exterior covering, along with its then-unusual wing shape. The gull wing, otherwise known as "the Polish wing", was developed by Polish
aeronautical engineer
Aerospace engineering is the primary field of engineering concerned with the development of aircraft and spacecraft. It has two major and overlapping branches: aeronautical engineering and astronautical engineering. Avionics engineering is sim ...
Zygmunt Puławski
Zygmunt Puławski (October 24, 1901 – March 21, 1931) was a Polish aircraft designer and pilot. He invented a gull-wing aircraft design, also known as "Puławski wing" and designed a series of Polish PZL fighters.
He was born in Lublin. In ...
; it possessed several advantages over its biplane contemporaries.
One such benefit was the thin profile it presented as it drew near to the fuselage, which avoided obstructing the exterior view for the pilot. The wings used a modified Bartler 37/11a aerofoil section, sharply
tapering in
chord and thickness towards the tips and roots and incorporating an upwards twist towards the
trailing edge
The trailing edge of an aerodynamic surface such as a wing is its rear edge, where the airflow separated by the leading edge meets.Crane, Dale: ''Dictionary of Aeronautical Terms, third edition'', page 521. Aviation Supplies & Academics, 199 ...
for improved visibility; they were largely composed of
duralumin, including the twin spars, ribs, and corrugated exterior, which was smooth on the
leading edge
The leading edge of an airfoil surface such as a wing is its foremost edge and is therefore the part which first meets the oncoming air.Crane, Dale: ''Dictionary of Aeronautical Terms, third edition'', page 305. Aviation Supplies & Academics, ...
and wing tips.
The fuselage of the P.24 possessed an oval all-metal structure, the forward section of which comprising built-up
girder
A girder () is a support beam used in construction. It is the main horizontal support of a structure which supports smaller beams. Girders often have an I-beam cross section composed of two load-bearing ''flanges'' separated by a stabilizing ...
sections and the rear using a combination of transverse duralumin
bulkheads and smooth
stressed skin
In mechanical engineering, stressed skin is a type of rigid construction, intermediate between monocoque and a rigid frame with a non-loaded covering. A stressed skin structure has its compression-taking elements localized and its tension-taking ...
construction.
The tail unit, which shared similar construction to the wings, was fitted with a
cantilever
A cantilever is a rigid structural element that extends horizontally and is supported at only one end. Typically it extends from a flat vertical surface such as a wall, to which it must be firmly attached. Like other structural elements, a cant ...
fin
A fin is a thin component or appendage attached to a larger body or structure. Fins typically function as foils that produce lift or thrust, or provide the ability to steer or stabilize motion while traveling in water, air, or other fluids. Fin ...
, a braced tailplane, while the
elevator
An elevator or lift is a cable-assisted, hydraulic cylinder-assisted, or roller-track assisted machine that vertically transports people or freight between floors, levels, or decks of a building, vessel, or other structure. They a ...
s were furnished with
Flettner tabs. The P.24 was provided with a conventional "scissor-type" fixed
landing gear
Landing gear is the undercarriage of an aircraft or spacecraft that is used for takeoff or landing. For aircraft it is generally needed for both. It was also formerly called ''alighting gear'' by some manufacturers, such as the Glenn L. Martin ...
arrangement; each leg incorporated an independently spring
oleo-
pneumatic shock absorber, built by
Avia.
The wheels were furnished with spats and worked in conjunction with a fixed skid located almost directly underneath the aircraft's tail section. The undercarriage configuration was a
patent
A patent is a type of intellectual property that gives its owner the legal right to exclude others from making, using, or selling an invention for a limited period of time in exchange for publishing an enabling disclosure of the invention."A ...
ed innovation.
The P.24 was powered either by a
Gnome-Rhône 14K or
Gnome-Rhône 14N
The Gnome-Rhône 14N was a 14-cylinder two-row air-cooled radial engine designed and manufactured by Gnome-Rhône just before the start of World War II. A development of the Gnome-Rhône 14K, the 14N was used on several French and even one Ger ...
supercharged geared
radial engine
The radial engine is a reciprocating type internal combustion engine configuration in which the cylinders "radiate" outward from a central crankcase like the spokes of a wheel. It resembles a stylized star when viewed from the front, and is ...
, ranging in output from 900 hp to 1,050 hp, which drove a three-bladed metal
variable-pitch propeller.
[Cynk 1967, pp. 8-9.] The armament was a combination of 20 mm
Oerlikon FF
The FF were a series of 20mm autocannon introduced by Oerlikon in the late 1920s. The name comes from the German term ''Flügel Fest'', meaning ''wing mounted, fixed'', being one of the first 20mm guns to be small and light enough to fit into a fi ...
cannon and 7.92 mm
Colt
Colt(s) or COLT may refer to:
*Colt (horse), an intact (uncastrated) male horse under four years of age
People
* Colt (given name)
*Colt (surname)
Places
*Colt, Arkansas, United States
*Colt, Louisiana, an unincorporated community, United States ...
-
Browning machine guns in the wings. On the P.24A, P.24E and P.24F models, it was armed with a pair of cannon and a pair of machine guns, while the P.24B, P.24C and P.24G variants were armed with an arrangement of four machine guns. Fuel was housed with an internal 360 liter tank located within the fuselage; in case of fire or similar emergency situations, this tank could be jettisoned.
[Cynk 1967, p. 9.] On all production P.24s, the
canopy
Canopy may refer to:
Plants
* Canopy (biology), aboveground portion of plant community or crop (including forests)
* Canopy (grape), aboveground portion of grapes
Religion and ceremonies
* Baldachin or canopy of state, typically placed over an ...
was fully enclosed; according to Cynk, it provided pilots with exceptionally high levels of external visibility in comparison to other fighter aircraft of the era. The pilot's seat was adjustable and could accommodate either a back or seat-type
parachute; it was normally equipped with a
Borkowski
Borkowski ( ; feminine: Borkowska; plural: Borkowscy) or Borkowsky is a surname of Polish-language origin. The surname may refer to:
* Alfons Dunin-Borkowski (1870–1938), Polish painter
* Amy Borkowsky, American author and comedian
* Anna Bo ...
self-adjusting safety belt system.
Operational history
Greece
The
Royal Hellenic Air Force
, colours =
, colours_label =
, march =
, mascot =
, anniversaries = 8 November
, equipment =
, equipment_label ...
(EVA) was the only air force during the Second World War to operate the PZL.24 as its main fighter type. Two different subtypes, consisting of 30 P.24F and six P.24G, were ordered and delivered between 1937 and 1938.
[Cynk 1967, pp. 6-8.] Upon arrival, these were split between three Mirae Dioxeos (Fighter Squadrons): the 21st at
Trikala
Trikala ( el, Τρίκαλα; rup, Trikolj) is a city in northwestern Thessaly, Greece, and the capital of the Trikala regional unit. The city straddles the Lithaios river, which is a tributary of Pineios. According to the Greek National Stati ...
, 22nd at
Thessaloniki
Thessaloniki (; el, Θεσσαλονίκη, , also known as Thessalonica (), Saloniki, or Salonica (), is the second-largest city in Greece, with over one million inhabitants in its metropolitan area, and the capital of the geographic region of ...
and 23rd at
Larissa. The only other operational Greek fighters, stationed further south, were eight
Bloch MB.151s and two each
Gloster Gladiator Mk Is and
Avia B-534 II, both of which were of limited value. During October 1940, the month in which Italy launched its invasion of Greece, the Polish fighter was the Greeks' only modern type in adequate numbers.
[Cynk 1967, p. 9.] However, by 1940, the P.24 was no longer a front-runner, despite its use of a powerful powerplant and a satisfactory armament; the P.24 had no speed advantage over the
Fiat CR.42, nor could it outfly the nimble Italian biplane, while it was considerably slower than the
Macchi MC.200 and the
Fiat G.50
The Fiat G.50 ''Freccia'' ("Arrow") was a World War II Italian fighter aircraft developed and manufactured by aviation company Fiat. Upon entering service, the type became Italy’s first single-seat, all-metal monoplane that had an enclosed ...
it was often pitted against. Its armament was the only real advantage against the Italian fighters, whose reliance on the slow-firing Breda-SAFAT 12.7mm machine guns proved detrimental.
[Cynk 1967, p. 11.]
The P.24F, armed with a pair of 20mm Oerlikon FF cannon and two machine guns, gave the Greeks a temporary edge in combat until lack of ammunition and spares forced EVA to re-arm all P.24Fs with 4x Colt–Browning 7.7 mm MG40 machine guns. Overall, the P.24s performed gallantly during the early period of the conflict, holding their own against impossible numerical odds and despite the fact that their main target were enemy bombers, which forced them to fight at a disadvantage against enemy fighters.
[Cynk 1967, pp. 9-10.] Italian claims of easy superiority over the Albanian front were vastly exaggerated and their kill claims even exceeded the total number of operational fighters on the Greek side. In total, Greek fighter losses in combat came to 24 aircraft, while the Greek fighter pilots claimed to have achieved 64 confirmed kills and 24 probables, around two-thirds of which were bombers). By April 1941, however, lack of spares and attrition had forced EVA to merge the five surviving P.24s into one understrength squadron, which was supported by five
Gloster Gladiator
The Gloster Gladiator is a British biplane fighter. It was used by the Royal Air Force (RAF) and the Fleet Air Arm (FAA) (as the Sea Gladiator variant) and was exported to a number of other air forces during the late 1930s.
Developed private ...
Mk I and II's and the two surviving MB.151s. That month, these remaining fighters fought hopelessly against the
Luftwaffe
The ''Luftwaffe'' () was the aerial-warfare branch of the German ''Wehrmacht'' before and during World War II. Germany's military air arms during World War I, the ''Luftstreitkräfte'' of the Imperial Army and the '' Marine-Fliegerabtei ...
onslaught, scoring 4 kills (two
Hs-126, one
Ju 87B
The Junkers Ju 87 or Stuka (from ''Sturzkampfflugzeug'', "dive bomber") was a German dive bomber and ground-attack aircraft. Designed by Hermann Pohlmann, it first flew in 1935. The Ju 87 made its combat debut in 1937 with the Luftwaffe's Cond ...
and one
Do 17) while losing most of their surviving aircraft on the ground.
[Cynk 1967, pp. 10-11.] None of the Puławski fighters are believed to have survived the conflict.
Romania
Prior to its procurement of the P.24, the
Romanian Air Force
The Romanian Air Force (RoAF) ( ro, Forțele Aeriene Române) is the air force branch of the Romanian Armed Forces. It has an air force headquarters, an operational command, five airbases and an air defense brigade. Reserve forces include one ai ...
had already adopted the P.11F, which was manufactured under license by
Industria Aeronautică Română
Industria Aeronautică Română (IAR) (now IAR S.A. Brașov) or Romanian Aeronautic Industry in English, is a Romanian aerospace manufacturer. It is based in Ghimbav, near Brașov, Romania.
IAR was founded in 1925 with the aid of the Romanian g ...
(IAR) in Romania. The Romanian Air Force acquired a production license for the type along with an initial batch of six Polish-built P.24Es, which served as pattern aircraft. The P.24E was specifically designed in conform with the requirements set out by the Romanian Air Force, including compatibility with its IAR-built model of the 14K engine, its two-cannon and two-machine gun armament, and various refinements and aerodynamic improvements.
Under the established licensing agreement, IAR proceeded with the construction of 25 ''IAR P.24E'' fighters by IAR between 1937 and 1939. According to Cynk, the P.24E had played a significant role in the development of a new Romanian low-wing
monoplane
A monoplane is a fixed-wing aircraft configuration with a single mainplane, in contrast to a biplane or other types of multiplanes, which have multiple planes.
A monoplane has inherently the highest efficiency and lowest drag of any wing con ...
fighter, which was designated as the
IAR 80
The IAR 80 was a Romanian World War II low-wing monoplane, all-metal monocoque fighter and ground-attack aircraft. When it first flew, in 1939, it was comparable to contemporary designs being deployed by the airforces of the most advanced milita ...
. Specifically, the new fighter had adopted a fuselage which had been derived from the P.24, along with a nearly-identical tail section, which was paired up to a new
cantilever
A cantilever is a rigid structural element that extends horizontally and is supported at only one end. Typically it extends from a flat vertical surface such as a wall, to which it must be firmly attached. Like other structural elements, a cant ...
wing and an inwardly-retractable undercarriage.
In Romanian service, the type saw combat action during the Second World War; early on, Romanian P.24s were used to guard the capital city of
Bucharest
Bucharest ( , ; ro, București ) is the capital and largest city of Romania, as well as its cultural, industrial, and financial centre. It is located in the southeast of the country, on the banks of the Dâmbovița River, less than north of ...
and the
Ploieşti oilfields from attacks by
Soviet
The Soviet Union,. officially the Union of Soviet Socialist Republics. (USSR),. was a transcontinental country that spanned much of Eurasia from 1922 to 1991. A flagship communist state, it was nominally a federal union of fifteen nation ...
bombers during the start of
Operation Barbarossa
Operation Barbarossa (german: link=no, Unternehmen Barbarossa; ) was the invasion of the Soviet Union by Nazi Germany and many of its Axis allies, starting on Sunday, 22 June 1941, during the Second World War. The operation, code-named after ...
. Flying from
Otopeni military airbase, the P.24 fighters reportedly managed to shoot down 37
VVS bombers, which were typically unescorted and thereby more vulnerable to interception. The P.24E was also routinely used for ground attack missions until the end of 1941; however, after 1942, the type was relegated to training duties because of its obsolescence in the face of improved opposition fighter aircraft.
Variants
During the development of Puławski fighters, a new version of the P.11, the P.11c, was developed for the Polish Air Force. It had a new, reconfigured fuselage, and the radial engine was lowered to give a pilot a better view. These changes were applied also to the new P.24 prototype, flown in 1936.
The P.24A and P.24B models could carry 4 x 12.5 kg bombs, while the P.24C, F and G could carry 2 x 50 kg bombs.
;P.24/I
:First prototype, powered with a
Gnome-Rhône 14Kds engine (760 hp), armed with two 7,92 mm Vickers wz. E machine guns.
;P.24/II ''Super P.24''
:Second prototype, powered with a Gnome-Rhône 14Kds engine from P.24/I initially, later with Gnome-Rhône 14Kfs engine (930 hp), armed with two 20 mm Oerlikon F guns and two 7,92 mm Vickers wz. E machine guns.
;P.24/III ''Super P.24 bis''
:Third prototype, powered with a Gnome-Rhône 14Kfs, armed with two 20 mm Oerlikon FFS guns and two 7,92 mm Vickers wz. E machine guns.
;P.24A
:Armed like P.24/III.
;P.24B
:The P.24B version was armed with four machine guns.
;P.24C
:The P.24C was armed with four machine guns and two 50 kg bombs.
;P.24D
:The P.24D was developed for sale to
Hungary
Hungary ( hu, Magyarország ) is a landlocked country in Central Europe. Spanning of the Pannonian Basin, Carpathian Basin, it is bordered by Slovakia to the north, Ukraine to the northeast, Romania to the east and southeast, Serbia to the ...
, but it was not completed, Hungary purchasing the
Fiat CR.32 instead.
;P.24E
:The P.24E version was license-built in
Romania
Romania ( ; ro, România ) is a country located at the crossroads of Central, Eastern, and Southeastern Europe. It borders Bulgaria to the south, Ukraine to the north, Hungary to the west, Serbia to the southwest, Moldova to the east, and ...
by
Industria Aeronautică Română
Industria Aeronautică Română (IAR) (now IAR S.A. Brașov) or Romanian Aeronautic Industry in English, is a Romanian aerospace manufacturer. It is based in Ghimbav, near Brașov, Romania.
IAR was founded in 1925 with the aid of the Romanian g ...
as the IAR P.24E.
;P.24F
:The P.24F was armed with two cannon and two machine guns and bombs and powered with the more powerful
Gnome-Rhône 14N-07 engine.
;P.24G
:The last production version was the P.24G, produced from 1937 and powered with the more powerful
Gnome-Rhône 14N-07 engine. The P.24G was armed with four machine guns and bombs.
;P.24H
:The P.24H was to be powered with a
Gnome-Rhône 14N-21 engine (1,100 hp) and carry four cannon or two cannon and two machine guns, but it was not completed. The P.24H was considered for purchase by the Polish Air Force, but progress was slow due to the P.24's similarity to the PZL P.11, which was already in service, and also interest in the hypothetically superior
PZL.50 Jastrząb then under development.
World War II
World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the vast majority of the world's countries—including all of the great powers—forming two opposing ...
started before any of these plans could be realized.
;P.24J
:The P.24J version was to be armed with four cannon and was to be sold for export.
Operators
![GreekPZLP24](https://upload.wikimedia.org/wikipedia/commons/6/65/GreekPZLP24.jpg)
;
*The
Bulgarian Air Force ordered 14 PZL P.24Bs in 1937–1938. Bulgaria placed a repeat order for 20 PZL P.24C,
[Cynk 1967, p. 7.] to be delivered by the end of 1938. It later ordered 26 PZL P.24Fs, 22 of which were delivered from Poland in July 1939, just before the outbreak of World War II. The remaining four, lacking propellers, were bombed in the Okecie factory in September 1939 by the Germans. Total: 56 PZL P.24B/C/F
;
*The
Royal Hellenic Air Force
, colours =
, colours_label =
, march =
, mascot =
, anniversaries = 8 November
, equipment =
, equipment_label ...
bought 30 P.24Fs and six P.24Gs in 1936. Delivered 1937–38. All Fs eventually re-armed with 4x Colt–Browning 7.7mm MGs.
;
*The
Royal Romanian Air Force
The Air Force branch of the Royal Romanian forces in World War II was officially named the (ARR), or the Romanian Royal Aeronautics, though it is more commonly referred to in English histories as the (Royal Romanian Air Force, FARR), or simply ...
ordered five PZL P.24E fighters in 1937 and built 25 IAR P.24E aircraft under license.
[Axworthy 1995, p. 254.]
;
*The
Turkish Air Force
The Turkish Air Force ( tr, ) is the aerial warfare service branch of the Turkish Armed Forces. The Turkish Air Force can trace its origins back to June 1911 when it was founded by the Ottoman Empire, however, the air force as it is known to ...
ordered 14 P.24A and 26 P.24C, delivered by 1937. Another 20 P.24A/Cs were built under license in Turkey in
Kayseri, followed by an additional 30 P.24G aircraft.
Survivors
The only surviving example of a PZL P.24 in the world is an example in Turkey. Photographs of the Turkish museum piece show a variety of serial numbering (2015, 2017, 2145, 2147) and are shot at different locations: (
Ankara
Ankara ( , ; ), historically known as Ancyra and Angora, is the capital of Turkey. Located in the central part of Anatolia, the city has a population of 5.1 million in its urban center and over 5.7 million in Ankara Province, maki ...
and
Istanbul
)
, postal_code_type = Postal code
, postal_code = 34000 to 34990
, area_code = +90 212 (European side) +90 216 (Asian side)
, registration_plate = 34
, blank_name_sec2 = GeoTLD
, blank_i ...
), but original aircraft is mistaken with one full-scale fiberglass replica.
Specifications (P.24A, P.24B, P.24C)
See also
References
Citations
Bibliography
* Axworthy, Mark. ''Third Axis, Fourth Ally''. London: Arms and Armour, 1995. .
* Bernád, Dénes. ''Rumanian Air Force: The Prime Decade 1938-1947''. Carrollton, TX: Squadron/Signal Publications Inc, 1999. .
*
* Cynk, Jerzy B. ''The P.Z.L. P-24 (Aircraft in Profile no. 170)''. Leatherhead, Surrey, UK: Profile Publications Ltd., 1967.
* Eberspacher, Warren and Jan P. Koniarek. ''PZL Fighters Part Three - P.24 Variants''. Austin, CO: Creative & Customized Support, 2002.
* Glass, Andrzej. ''Polskie konstrukcje lotnicze 1893-1939'' (in Polish). Warszawa, Poland: WKiŁ, 1976. No ISBN.
* Glass, Andrzej. ''PZL P.24 (Wydawnictwo Militaria 2)'' (in Polish). Warszawa, Poland: Wydawnictwo Militaria, 1994. .
* Glass, Andrzej. ''PZL P.24 A-G (Monographie no.7)'' (Bilingual Polish/English). Lublin, Poland: Kagero, 2004. .
* Green, William. ''War Planes of the Second World War, Volume Three: Fighters''. London: Macdonald & Co.(Publishers) Ltd., 1961. .
* Napier, Sid. "Le PZL P.24 en Grèce" (In French). ''AirMagazine'', No. 34, October–November 2006.
* Skulski, Przemyslaw. ''PZL P.24 (Seria "Pod Lupą" 15)'' (in Polish with English captions). Wrocław, Poland: ACE Publication, 2002. .
* Skulski, Przemyslaw. "PZL P.24, The Last Polish Gull-wing Fighter". ''Scale Aviation Modeller International'', Vol. 10, Issue 9, September 2004.
External links
A large collection of Greek P24 photos and profiles of most individual aircraft
{{Authority control
1930s Polish fighter aircraft
World War II Polish fighter aircraft
Gull-wing aircraft
PZL aircraft
Single-engined tractor aircraft
Aircraft first flown in 1933