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WORLD WAR 1

SPAD S.XI

Biplane Fighter Aircraft (1917)

The two-seat SPAD S.XI was dogged by issues which led to limited production during World War 1.

Authored By: Staff Writer | Last Edited: 06/04/2018 | Content ©www.MilitaryFactory.com | The following text is exclusive to this site.

The storied engineering career of Frenchman Louis Bechereau spanned decades and several popular designs during World War 1 (1914-1918). Hired by Armand Deperdussin to head design at Societe de Production des Aeroplanes Deperdussin ("S.P.A.D."), Bechereau delivered the early SPAD S.VII and later SPAS S.XIII. In between these two notable designs fell the oft-forgotten SPAD S.XI, a two-seat reconnaissance-minded biplane fighter attempting to fulfill Specification C2 for the French Air Service. The SPAD S.XI did not prove itself an outright success as other SPAD designs did and witnessed only a short shelf-life during the war, dogged by issues throughout its career. This led to a rather limited production reach of about 1,000 aircraft in the series.

To fulfill the French air Service (Aeronautique Militaire) requirements, Bechereau attempted to continue using the proven qualities of his previous single-seat biplane fighter offerings. A longer fuselage was necessary when incorporating a second observer's/gunner's cockpit aft of the pilot. Sections of the wings were cut out for improved viewing while many other qualities of the design remained consistent with the period - the front-mounted engine driving a two-bladed wooden propeller, parallel struts and cabling to stiffen and control the "over-under" wing structure and conventional single-finned tail unit. The undercarriage was wheeled though fixed through reinforced struts and the tail supported by a simple skid. The pilot was given a single fixed, forward-firing 7.7mm Vickers series machine gun and the observer could manage an optional 7.7mm Lewis machine gun on a trainable mounting. The aircraft emerged under the company model number of "SPAD 11", also written as SPAD S.XI.

Power to the S.XI was served through 1 x Hispano-Suiza 8Bc series V-8 water-cooled engine of 200 horsepower and this allowed a maximum speed was 112 miles per hour with an mission endurance time of approximately 2.25 hours. The aircraft's service ceiling was listed at 23,000 feet with a rate-of-climb of 9,850 feet reached in roughly 12.5 minutes. Some airframes were also fitted with a Renault 12-cylinder engine instead of the aforementioned Hispano-Suiza installation, though this powerplant actually reduced performance figures and was not popular.

The SPAD S.XI joined the war during 1917 and eventually proved itself not a success. The modified single-seat fighter approach for a larger two-seat design made the airframe tricky in its handling while performance from the engine of choice proved underwhelming. The type did hold characteristics that superseded some existing types then in service with French forces so the aircraft still managed to serve in notable numbers. It managed a frontline status until the fall of 1918 before being replaced by the SPAD S.XVI - itself a direct offshoot of the S.XI though outfitted with a Lorraine-Dietrich engine of 250 horsepower. These proved no better than the originals but were kept in action nonetheless.

Operators beyond the French Air Service became Belgium, Italy, Japan, Russia (into the Soviet Union years), Uruguay and the United States (American Expeditionary Force - "AEF").

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