__NOTOC__ The Blériot-SPAD S.81 (S.81 C.1) was a French

fighter aircraft Fighter aircraft (early on also ''pursuit aircraft'') are military aircraft designed primarily for air-to-air combat. In military conflict, the role of fighter aircraft is to establish air supremacy, air superiority of the battlespace. Domina ...

developed in 1923 to a requirement by the

French Air Force The French Air and Space Force (, , ) is the air force, air and space force of the French Armed Forces. Formed in 1909 as the ("Aeronautical Service"), a service arm of the French Army, it became an independent military branch in 1934 as the Fr ...

. It was flown competitively against the Dewoitine D.1 and was selected over that aircraft due to the Dewoitine's more radical design, leading to an order for 80 aircraft. The S.81 was a single-bay

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 ...

of conventional configuration with I-shaped

interplane 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 struts, which act in ...

s and lacking Herbemont's usual swept upper wing. It featured a wooden

fuselage The fuselage (; from the French language, French ''fuselé'' "spindle-shaped") is an aircraft's main body section. It holds Aircrew, crew, passengers, or cargo. In single-engine aircraft, it will usually contain an Aircraft engine, engine as wel ...

monocoque Monocoque ( ), also called structural skin, is a structural system in which loads are supported by an object's external skin, in a manner similar to an egg shell. The word ''monocoque'' is a French term for "single shell". First used for boats, ...

construction and metal wings skinned in fabric. Production versions differed from the prototypes in having a lengthened fuselage and larger tail

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. F ...

Variants

;S.81.01:two prototypes, powered by a Hispano-Suiza 8Fb V-8 engine. The second aircraft was used for static tests only ;S.81/1:production version, powered by a Hispano-Suiza 8Fb V-8 engines, designated S.81 C.1 (S.81 ''Chasseur'' - single-seater) in air force service. ;S.81''bis'':single example of racer version developed for the

Coupe Michelin The Michelin Cup refers to a number of competitions sponsored by the French tyre manufacturer Michelin for long-distance flight made in aeroplanes. The first Michelin prize was announced in March 1908. The principal prize, to be awarded annually f ...

race. Performance poor. ;S.81/2:single machine to evaluate alternative

radiator A radiator is a heat exchanger 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 ...

design. ;S.81/3:single machine to evaluate alternative radiator design ;S.81/4:single machine to evaluate wooden wing design ;S.81/6:racer converted from the S.81-''bis''

Variants

Operators

Specifications (S.81/1)

See also

References

Bibliography

Further reading