Origins In February 1915, Swiss designer
Marc Birkigt had created
an overhead cam aviation powerplant based on his
Hispano-Suiza V8 automobile engine, resulting in a engine capable of producing at 1,400 rpm. Further refinement brought the power to by July 1915. Given the engine's potential, French officials ordered called upon aircraft designers to create a new high-performance fighter around the engine, called the
Hispano-Suiza 8A, with production to begin as soon as possible.
Louis Béchereau, chief designer of the
SPAD company, quickly produced a prototype fighter with the new engine. The SPAD V was a version of the
SPAD S.A two-seat "pulpit fighter", which dispensed with the so-called "pulpit" which carried the observer in front of the propeller.
Design One of many many common design features between the new SPAD V and the S.A.2 was the use of a single-bay biplane wing with additional struts mounted mid-bay at the point of junction of the flying and landing wires. This design simplified rigging and reduced drag. The fuselage was of the standard construction for the time, consisting of a wooden frame covered with fabric, while the forward part was covered with metal sheeting. A .303 (7.7mm)
Vickers machine gun was installed above the engine, synchronized to fire through the propeller arc. The prototype was also fitted with a large
spinner, to be abandoned later. Another common design feature of both the "pulpit fighters" and the S.VII – also shared with the S.XIII – was the pushrod aileron control linkage, which used a pair of exposed, 90° bellcranks protruding from the lower wing panels to operate vertical pushrods, going up to forward-projecting aileron control horns. SPAD test pilot Bequet flew the SPAD V for the first time in April 1916. Flight testing revealed excellent maximum speed ( and climb rate of 4.5 min to ). The airframe's sound construction also enabled a good diving performance. In comparison, the
Nieuport 17 sesquiplane fighters that equipped a large part of the fighter units couldn't dive as fast because of their lower weight, but could outclimb the SPADs by a wide margin. The high diving speed promised to give lower-skilled Allied pilots the initiative to engage or leave combat against heavier German fighters. If the new fighter was a rugged and stable shooting platform, many pilots regretted its lack of manoeuvrability. An initial production contract was made on 10 May 1916, calling for 268 machines, to be designated SPAD VII C.1 (C.1, from
avion de chasse in French, indicating the aircraft was a fighter, while the 1 indicated it was a single seater). Early production aircraft had two ammunition drums: one for the loaded canvas cartridge belt, and one to hold the empty belt after the rounds had been fired. However, dealing with the fabric belt as it came out of the gun was a significant problem, and was prone to jamming, which was only solved when Prideaux disintegrating ammo links were introduced. With the initial teething problems solved, several subcontractors began producing the SPAD VII under license. The subcontractors included the firms Grémont, Janoir, Kellner et Fils,
de Marçay, Société d'Etudes Aéronautiques, Régy and Sommer. It was not, however, until February 1917 that the last examples from the initial batch of 268 aircraft was delivered. In early 1917, an improved version of the engine developing , the Hispano-Suiza 8Ab, was made available. This provided the SPAD VII with better performance, the top speed increasing from . The new engine gradually became the standard powerplant for the SPAD VII and by April 1917, all newly produced aircraft were equipped with it.
Variants and experiments Numerous experiments were made to improve performance. A Renault V8 powerplant was tested but required major redesign and the performance was not worthwhile. A supercharged Hispano-Suiza engine was also tested, but also failed to significantly improve performance. Different wing profiles were tested but were not incorporated in production models. One field modification was applied in Czechoslovakia after the war when the undercarriage struts of one S.VII were faired over. Early in the development of the S.VII, the British RFC and RNAS showed an interest in the new fighter. An initial order for 30 aircraft was made but production difficulties kept the delivery rate very low, with production not even meeting French requirements. As the RFC was encountering stronger opposition over the Front, production of the S.VII was initiated in the United Kingdom.
Blériot & SPAD Aircraft Works and
Mann, Egerton & Co. Ltd. were supplied with plans and sample aircraft and to begin production as soon as possible. The first British-built S.VII was flown and tested in April 1917, and the first aircraft was reported to have performance equal to that of French models. There were however differences between the two. The British were worried about the light armament of the S.VII as most German fighters were now carrying two guns and experiments were made with an extra machine gun on the S.VII. One aircraft was fitted with a Lewis machine gun on the top wing and tested at Martlesham Heath in May 1917, while front line units also made field modifications with
Foster mounts commonly associated with the
Royal Aircraft Factory S.E.5. The performance penalty was too drastic for the installation to become standard, and most S.VIIs flew with a single Vickers. Other distinguishing features of the British-built S.VIIs included a gun fairing and a solid cowling access panel. The gun fairing partially covered the gun and extended rearwards, replacing the windshield. This, however, seriously limited pilot vision to the front and, although retained on training aircraft, was removed on aircraft destined for front line units. The bulged engine access panel located under the exhaust pipe on British models was made of a solid sheet of metal, in place of the louvered panel fitted on French production models. Some British SPADs were also fitted with small spinners on the prop hub. It was soon apparent that British production lines had lower quality standards than their French counterparts, degrading performance and handling. Poor fabric sewing, fragile tailskids and ineffective radiators plagued the British SPADs. Photographic evidence shows that some had the cylinder bank fairings, or even the entire upper engine cowling, cut out to compensate for the malfunctioning radiators. As a result, most British-built S.VIIs were used for training, with front line units equipped with French-built models. After some 220 had been produced, British production of the S.VII was halted in favour of comparable British types that were becoming available. In a similar fashion, the
Dux factory in Moscow produced approximately 100 S.VIIs under licence in 1917, with engines supplied by France. It would appear the engines were often used and/or of lower quality, and that Dux used lower-grade material in building the airframes. This combination of extra weight and weaker powerplants significantly reduced performance. The total number of aircraft produced is uncertain, with sources varying from 3,825 to some 5,600 SPAD S.VIIs built in France, 220 in the United Kingdom and approximately 100 in Russia. French production numbers may include other SPAD models, and/or S.VIIs produced by other contractors. The
SPAD XII began as an enlarged S.VII, equipped with a 37 mm cannon. It was a distinct type rather than a variant of the S.VII though. the S.VII can be distinguished from both the S.XII and the later and larger S.XIII by having unraked cabane struts, connecting the top wing to the fuselage, as well as differences in armament. Late models were equipped with or Hispano-Suiza engines. The upgrade produced a top speed of . ==Operational history==