The SIAI S.52 was an Italian fighter

prototype A prototype is an early sample, model, or release of a product built to test a concept or process. It is a term used in a variety of contexts, including semantics, design, electronics, and Software prototyping, software programming. A prototyp ...

of 1924.

Design and development

In 1919, Alessandro Marchetti (1884–1966) designed the

Marchetti MVT The Marchetti MVT, later renamed SIAI S.50, was an Italian fighter of 1919 and the early 1920s. Design and development Alessandro Marchetti (1884–1966) designed the MVT (for "Marchetti-Vickers-Terni"), a single-seat, all-metal biplane with i ...

fighter, renamed the SIAI S.50 in 1922 when Marchetti joined the SIAI company as its chief designer. SIAI entered the S.50 in the 1923 ''

Regia Aeronautica The Italian Royal Air Force (''Regia Aeronautica Italiana'') was the name of the air force of the Kingdom of Italy. It was established as a service independent of the Royal Italian Army from 1923 until 1946. In 1946, the monarchy was abolis ...

'' (Italian Royal Air Force) fighter contest, even though the S.50 was powered by a 212-

kilowatt The watt (symbol: W) is the unit of power or radiant flux in the International System of Units (SI), equal to 1 joule per second or 1 kg⋅m2⋅s−3. It is used to quantify the rate of energy transfer. The watt is named after James Wa ...

(285-

horsepower Horsepower (hp) is a unit of measurement of power, or the rate at which work is done, usually in reference to the output of engines or motors. There are many different standards and types of horsepower. Two common definitions used today are the ...

) SPA 62a six-cylinder engine instead of the 224-kilowatt (300-horsepower)

Hispano-Suiza Hispano-Suiza () is a Spanish automotive–engineering company. It was founded in 1904 by Marc Birkigt and Damian Mateu as an automobile manufacturer and eventually had several factories in Spain and France that produced luxury cars, aircraft en ...

HS 42 eight-cylinder water-cooled engine required by the Italian

Air Ministry The Air Ministry was a department of the Government of the United Kingdom with the responsibility of managing the affairs of the Royal Air Force, that existed from 1918 to 1964. It was under the political authority of the Secretary of State ...

s specification for entrance in the contest. Despite this, the S.50 attracted enough ''Regia Aeronautica'' interest to prompt it to acquire three S.50 fighters from SIAI for evaluation, although a proposal to order twelve S.50 aircraft never bore fruit. Marchetti decided to design a derivative of the S.50 powered by the HS 42 engine for entry in the 1923 fighter contest. The resulting S.52 was a single-seat, all-metal

biplane A biplane is a fixed-wing aircraft with two main wings stacked one above the other. The first powered, controlled aeroplane to fly, the Wright Flyer, used a biplane wing arrangement, as did many aircraft in the early years of aviation. While ...

with its

fuselage The fuselage (; from the French ''fuselé'' "spindle-shaped") is an aircraft's main body section. It holds crew, passengers, or cargo. In single-engine aircraft, it will usually contain an engine as well, although in some amphibious aircraft t ...

suspended between the upper and lower wings. The after part of the fuselage itself was flattened to serve as an

airfoil An airfoil (American English) or aerofoil (British English) is the cross-sectional shape of an object whose motion through a gas is capable of generating significant lift, such as a wing, a sail, or the blades of propeller, rotor, or turbine. ...

. The semi-elliptical

wing A wing is a type of fin that produces lift while moving through air or some other fluid. Accordingly, wings have streamlined cross-sections that are subject to aerodynamic forces and act as airfoils. A wing's aerodynamic efficiency is expres ...

s were extremely thin in section and larger in area than those of the S.50, and used

aileron An aileron (French for "little wing" or "fin") is a hinged flight control surface usually forming part of the trailing edge of each wing of a fixed-wing aircraft. Ailerons are used in pairs to control the aircraft in roll (or movement around ...

s to allow lateral control rather than the

wing warping Wing warping was an early system for lateral (roll) control of a fixed-wing aircraft. The technique, used and patented by the Wright brothers, consisted of a system of pulleys and cables to twist the trailing edges of the wings in opposite direc ...

the S.50 employed. The S.50s all-moving tail surfaces were replaced in the S.52 by a conventional tail unit which combined fixed and moving surfaces. The engine drove a two-bladed

propeller A propeller (colloquially often called a screw if on a ship or an airscrew if on an aircraft) is a device with a rotating hub and radiating blades that are set at a pitch to form a helical spiral which, when rotated, exerts linear thrust upon ...

, and the S.52 was armed with two fixed, forward-firing 7.7-millimeter (0.303-inch)

Vickers machine gun The Vickers machine gun or Vickers gun is a Water cooling, water-cooled .303 British (7.7 mm) machine gun produced by Vickers Limited, originally for the British Army. The gun was operated by a three-man crew but typically required more me ...

s synchronized to fire through the propeller.

Operational history

The S.52 was too late for the 1923 fighter contest, first flying in 1924. Two prototypes – designated MM.3 and MM.4 – were built, but no Italian production order ensued. In 1925, a proposal was made to re-engine one of the prototypes with a 306-kilowatt (410-horsepower)

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A 20 engine, which was projected to give it a top speed of 285 kilometers per hour (177 miles per hour). This conversion never took place. The other prototype was shipped to

Latin America Latin America or * french: Amérique Latine, link=no * ht, Amerik Latin, link=no * pt, América Latina, link=no, name=a, sometimes referred to as LatAm is a large cultural region in the Americas where Romance languages — languages derived f ...

for demonstration flights, one of which was a 1927 flight from

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Paraguay Paraguay (; ), officially the Republic of Paraguay ( es, República del Paraguay, links=no; gn, Tavakuairetã Paraguái, links=si), is a landlocked country in South America. It is bordered by Argentina to the south and southwest, Brazil to th ...

. SIAI had learned that the

Paraguayan Air Arm The Armed forces of Paraguay ( es, Fuerzas Armadas de Paraguay) consist of the Paraguayan army, navy (including naval aviation and marine corps) and air force. The constitution of Paraguay establishes the president of Paraguay as the commander- ...

was purchasing airplanes, so the S.52 made a series of successful flights at the Paraguayan Military Aviation School. The Paraguayan government decided to buy it in 1927 – the first fighter Paraguay had ever bought and its only fighter until the arrival of seven Wibault 73 C.1 aircraft in 1928 – but placed no order for additional S.52s. The Paraguayan S.52 received the

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16 in 1932. It apparently took no part in the

Chaco War The Chaco War ( es, link=no, Guerra del Chaco, gn, Cháko Ñorairõtrainer at Paraguays Ñu-Guazú Military Aviation School until it was destroyed in an accident on 8 May 1933 at the Ñu-Guazú airfield. Its pilot,

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Emilio Rocholl, survived the crash.Sapienza.

Operators

; *

Specifications

Notes: *Time to 1,000 m (3,281 ft): 1 min 30 sec

Notes

References