SPAD S.A

SPAD S.A
French SPAD S.A-2 of Escadrille N49 in Corzieux.
Role	Fighter
Manufacturer	Société Pour l'Aviation et ses Dérivés (SPAD)
Designer	Louis Béchereau
First flight	1915
Introduction	1915
Status	retired
Primary users	Russian Empire France
Produced	1915-1916
Number built	107

The SPAD S.A (also called S.A.L.) was a French two-seat tractor biplane first flown in 1915. It was used by France and Russia in the early stages of the First World War in the fighter and reconnaissance roles. It was a somewhat unusual aircraft that carried its observer in a nacelle ahead of both wing and engine.

The SPAD A.1 prototype was the first aircraft produced by SPAD following its reorganization from the pre-war Deperdussin company. The chief designer, Louis Béchereau, had been involved in designing that firm's successful monocoque racing monoplanes, and many design details were carried over from the Deperdussins.

The aircraft was designed to carry not only its pilot in the normal position, but also an observer in a streamlined nacelle ahead of the propeller. This configuration was an attempt to combine the advantages of the tractor and the pusher types, giving the observer a clear field of view to the front and sides without the drag penalty of the typical pusher. However, communication between the pilot and the observer was nearly impossible. The pulpit (as it was known in English) or basket (as it was referred to in Russian) vibrated badly and, in multiple cases, parted company from the rest of the aircraft while in flight. Like many pushers, it also put the observer at risk of being crushed in even a relatively mild crash or "nose-over". A British evaluation of the type suggested "it would be expensive in observers if flown by indifferent pilots".

While not originally designed explicitly as a gunner's position, early combat experience had shown a need for forward-firing machine guns. But mechanisms to allow a gun to fire through the propeller were not yet available, and the observer's nacelle on the S.A-1 represented a temporary solution.

On all but the earliest prototypes and the SPAD S.G, the nacelle was fitted with a light machine gun on a flexible tubular mount, and it incorporated air intakes on its sides and underside to redirect air toward the Le Rhône rotary engine, which was otherwise masked by the nacelle. Starting the engine required the prop to be swung from alongside the fuselage. The nacelle was hinged at the bottom to provide some access to the engine for maintenance, but this was insufficient, and additional sliding panels were added to the sides of the fuselage. A mesh screen behind the observer was intended to prevent propeller strikes. The first prototypes were unarmed, although one was fitted with dummy guns to represent the S.G., which differed by having one or more machine guns mounted in the nacelle, without any occupant. The S.G.'s guns were not accessible, which caused problems, and its performance was quickly eclipsed by other single-seat fighters, including the Nieuport 10 and Nieuport 11, so it received no orders.

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