The Potez 31 was a prototype

French French (french: français(e), link=no) may refer to: * Something of, from, or related to France ** French language, which originated in France, and its various dialects and accents ** French people, a nation and ethnic group identified with Franc ...

two-seat night fighter, flown in about 1928, intended to fill the Cn.2 specification for the

Armee de l'Air The French Air and Space Force (AAE) (french: Armée de l'air et de l'espace, ) is the air and space force of the French Armed Forces. It was the first military aviation force in history, formed in 1909 as the , a service arm of the French Army; ...

. Only one was built.

Design and development

The Potez 31 was a

parasol-wing A monoplane is a fixed-wing aircraft configuration with a single mainplane, in contrast to a biplane or other types of multiplane (aeronautics), multiplanes, which have multiple planes. A monoplane has inherently the highest efficiency and lowe ...

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 confi ...

derived from the monoplane Potez 25.36 variant. Its wing, with no dihedral, a

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, ...

swept at 6° and a low aspect ratio of about 5 was built around two spars and fabric covered. The outer panels were of almost constant chord apart from a slight decrease in sweep on their outer trailing edges. The tips were straight, angled and slightly blunted. These panels were braced by a pair of parallel struts from the lower

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 ...

longeron In engineering, a longeron and stringer is the load-bearing component of a framework. The term is commonly used in connection with aircraft fuselages and automobile chassis. Longerons are used in conjunction with stringers to form structural ...

on each side. Close to the fuselage the trailing edge curved forward to join a narrow chord centre section, improving the field of view from the

cockpit A cockpit or flight deck is the area, usually near the front of an aircraft or spacecraft, from which a Pilot in command, pilot controls the aircraft. The cockpit of an aircraft contains flight instruments on an instrument panel, and the ...

s. This section was supported over the fuselage by four inclined

cabane strut In aeronautics, bracing comprises additional structural members which stiffen the functional airframe to give it rigidity and strength under load. Bracing may be applied both internally and externally, and may take the form of strut, which act in ...

s from the upper fuselage longerons. Long-span

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 were controlled via

spades SPAdes (St. Petersburg genome assembler) is a genome assembly algorithm which was designed for single cell and multi-cells bacterial data sets. Therefore, it might not be suitable for large genomes projects. SPAdes works with Ion Torrent, PacBio ...

. Four

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longerons formed the basis of the fuselage, which was

plywood Plywood is a material manufactured from thin layers or "plies" of wood veneer that are glued together with adjacent layers having their wood grain rotated up to 90 degrees to one another. It is an engineered wood from the family of manufactured ...

-covered forward from the cockpit area. The gunner's position, with a rotatable machine gun mounting, was close behind the smaller cockpit for the pilot. Both were equipped with heating and oxygen. Aft of the gunner the fuselage was fabric-covered apart from curved plywood decking. A clipped triangular

tailplane A tailplane, also known as a horizontal stabiliser, is a small lifting surface located on the tail (empennage) behind the main lifting surfaces of a fixed-wing aircraft as well as other non-fixed-wing aircraft such as helicopters and gyroplane ...

mounted on the upper longerons carried near rectangular, horn-balanced

elevator An elevator or lift is a wire rope, cable-assisted, hydraulic cylinder-assisted, or roller-track assisted machine that vertically transports people or freight between floors, levels, or deck (building), decks of a building, watercraft, ...

s. The fin was straight-edged and the rudder also horn-balanced. The Potez 31 was powered by a

Hispano-Suiza 12G 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 ...

, a

W-12 engine A W12 engine is a twelve-cylinder piston engine where three banks of four cylinders are arranged in a W configuration around a common crankshaft. W12 engines with three banks of four cylinders were used by several aircraft engines from 1917 unti ...

, driving a two-blade propeller. A partially retractable honeycomb

radiator Radiators are heat exchangers used to transfer thermal energy from one medium to another for the purpose of cooling and heating. The majority of radiators are constructed to function in cars, buildings, and electronics. A radiator is always a ...

was mounted under the fuselage at the rear of the engine and fuel tanks were in the fuselage over the

centre of gravity In physics, the center of mass of a distribution of mass in space (sometimes referred to as the balance point) is the unique point where the weighted relative position of the distributed mass sums to zero. This is the point to which a force may ...

. It had a tail wheel undercarriage with main wheels on a split axle, centrally supported by a lateral V-strut from the fuselage lower longerons at the base of the forward wing struts. The outer ends were hinged on longitudinally mounted V-struts, the forward member rubber sprung, from the lower fuselage longerons at the bases of the two wing struts. Neither ''L'Aerophile'' nor ''L'Ailes'', two contemporary French aviation periodicals, record the date of the Potez 31's first flight or any subsequent history. Modern sources vary widely on the first flight, ranging at least from 27 December 1927 to 1929. The French newspaper ''Le Petit Parisien'' records that on 25 September 1929 the aircraft, flown by Marmier and Favreau, took off loaded with of fuel on the first stage of a straight-line flight record attempt to

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, although the attempt was abandoned due to poor weather.

Engine variations

''Data from:'' The sole Potex 31 was flown with the following engines: *

Hispano-Suiza 12Mb The Hispano-Suiza 12M was one of two new V-12 engine designs first run in 1927–1928. It produced about 375 kW (500 hp), was the first to use gas nitride hardening and introduced wet cylinder liners into Hispano-Suiza's aircraft engi ...

(V-12) *

Hispano-Suiza 12Ga 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 ...

(W-12) *

Hispano-Suiza 12Hb Hispano-Suiza piston aero-engines were predominantly piston engines produced by Hispano-Suiza in France, Spain, and under licence in the United Kingdom, the United States and Russia from the First World War through to the 1950s. Development of these ...

(V-12) * Lorraine-Dietrich 12Fb (W-12)

Specifications

Potez_31_3-view_Les_Ailes_September_6,1928

References

External links

Photo of a W-12 engined Potez 31 (probably the Lorraine 12F powered version)
{{Potez aircraft 031 1920s French fighter aircraft