SPAD S.XII

The SPAD S.XII or SPAD 12 was a French single-seat biplane fighter aircraft of the First World War developed from the successful SPAD VII by Louis Béchereau, chief designer of the Société Pour L'Aviation et ses Dérivés (SPAD).

SPAD S.XII
A USAAS SPAD S.XII in 1918.
Role Fighter
National origin France
Manufacturer SPAD
Designer Louis Béchereau
First flight 5 July 1917
Primary users Aéronautique Militaire
Red Army
Number built unknown, 300 ordered[1]
Developed from Spad S.VII

Development

The SPAD XII was inspired by the ideas of French flying ace Georges Guynemer, who proposed that a manoeuvrable single-seat aircraft be designed to carry a 37 mm cannon, a weapon which had previously been mounted only in large two-seat "pusher" aircraft such as the Voisin III. Béchereau took his own SPAD VII design as the starting point, but the many major and minor changes incorporated into the SPAD XII made it a quite different aircraft.

Restored HS.8Ca geared-output engine, similar to the 8Cb used on the SPAD S.XII
A geared-output shaft HS.8C engine for a SPAD S.XII, showing the elevated intake manifold to clear the 37mm cannon mounted in the "vee" between the cylinder banks.

The gun chosen for the SPAD XII was not the old Hotchkiss cannon but a new 37 mm Semi Automatique Moteur Canon (SAMC), built by Puteaux, for which 12 shots were carried. The Hispano-Suiza aviation engine had to be geared to allow the gun to fire through the propeller shaft. The SPAD XII also carried a single 0.303 inch synchronized (7.7 mm) Vickers machine gun mounted on the starboard side of the nose. In order to carry the heavy cannon the airframe was lengthened and the wingspan and wing area increased. The wingtips were rounded rather than squared off and the wings given a slight forward stagger. To accommodate the required geared output propshaft engine, which easily allowed for the hollow propeller shaft for the cannon to fire through, and power the resultingly heavier airframe, 587 kilograms (1,294 lb) compared to the 500 kilograms (1,100 lb) of the SPAD VII, the 180 bhp Hispano-Suiza 8 direct-drive Ab engine was replaced by the geared 220 bhp model 8Cb, and gave the SPAD XII a clockwise rotating propeller, as seen from a "nose-on" view.

Test flown by Guynemer, the early production models of the SPAD XII were highly successful after overcoming initial problems with the reduction gear between engine and propeller.[2] Other aces also had success with the new model. However, deliveries were slow, the SPAD VII and later SPAD XIII having top priority, and even the modest total of 300 aircraft which were ordered were not all completed. Best estimates are only 20 produced. Average pilots found the SPAD XII a difficult aircraft to master, and the cannon difficult to aim and fire, while manual reloading was difficult. The cockpit filled with fumes upon every firing. Its breech mechanism protruded into the cockpit and prevented the use of a conventional stick to control the aircraft, adding to the difficulties encountered by ordinary pilots. The control setup reverted to a split setup on either side of the pilot, a la Deperdussin.[3]

Service
The 13th Aero Squadron SPAD S.XII, showing the slight positive stagger of the wings.

No units were entirely equipped with SPAD XIIs. The unknown number of aircraft produced were issued in small numbers, intended for use only by the most skilled pilots, such as Rene Fonck, Lionel de Marmier, Fernand Henri Chavannes, Henri Hay de Slade, Albert Deullin and François Battesti. They were distributed one or two per squadron.[4] Few were delivered to combat units, eight being recorded on strength in April and again in October; this may be contrasted with the thousands of SPAD VIIs and SPAD XIIIs in service. Single examples for testing were delivered to the Royal Flying Corps[5] and one to the Aviation Section of the American Expeditionary Force, with the AEF's 13th Aero Squadron receiving the code "0", it was primarily flown by the 13th's Charles John Biddle.[6]

Operators
 France
 Russia /  Soviet Union
 Serbia
 United Kingdom
 United States
 Kingdom of Yugoslavia

Specifications (S.XII)

Data from The Complete Book of Fighters [7]

General characteristics

  • Crew: 1
  • Length: 6.4 m (21 ft 0 in)
  • Wingspan: 8 m (26 ft 3 in)
  • Height: 2.55 m (8 ft 4 in)
  • Wing area: 20.2 m2 (217 sq ft)
  • Empty weight: 587 kg (1,294 lb)
  • Gross weight: 883 kg (1,947 lb)
  • Powerplant: 1 × Hispano-Suiza 8Cb V-8 water-cooled piston engine, 164 kW (220 hp)
  • Propellers: 2-bladed fixed-pitch propeller

Performance

  • Maximum speed: 203 km/h (126 mph, 110 kn)
  • Endurance: 1 hour 45 minutes
  • Service ceiling: 6,850 m (22,470 ft) [5]
  • Time to altitude: 2,000 m (6,562 ft) 6 minutes 3 seconds

Armament

See also

Related development

References

Notes
Wikimedia Commons has media related to SPAD S.XII.
  1. "The Cannon Pioneers". Archived from the original on 2009-05-16.
  2. SPAD XII/XIII aces of World War I. pp. 7, 9.
  3. SPAD XII/XIII aces of World War I. pp. 8–9.
  4. SPAD XII/XIII aces of World War I. pp. 9–10.
  5. Bruce 1982, p. 560.
  6. Guttman, Jon (2002). SPAD XII/XIII Aces of World War I. Osprey Publishing. pp. 12, 14–15. ISBN 978-1-84176-316-3.
  7. Green and Swanborough 1994, pp. 542–543.

Bibliography
  • Bruce, J. M. The Aeroplanes of the Royal Flying Corps (Military Wing). London: Putnam, 1982. ISBN 0-370-30084-X.
  • Cony, Christophe (January 1995). "Le Spad XII Canon (1re partie)" [The Canon-armed SPAD XII]. Avions: Toute l'aéronautique et son histoire (in French) (23): 39–42. ISSN 1243-8650.
  • Davilla, James J., & Soltan, Arthur M., French Aircraft of the First World War. Stratford, Connecticut: Flying Machines Press, 1997. ISBN 0-9637110-4-0.
  • Green, William and Swanborough, Gordon. The Complete Book of Fighters. New York: Smithmark, 1994. ISBN 0-8317-3939-8.
  • Guttman, Jon, SPAD XII/XIII aces of World War I. Osprey Publishing, 2002. ISBN 1841763160, 9781841763163.
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