SPAD S.XII

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SPAD S.XII
Role biplane cannon-armed 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

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 7 by Louis Béchereau, chief designer of the Société Pour L'Aviation et ses Dérivés (SPAD).

Development[edit]

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 7 design as the starting point, but the many major and minor changes incorporated into the SPAD 12 made it a quite different aircraft.

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 kg compared to the 500 kg of the SPAD 7, 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.[citation needed] Best estimates are only 20 produced. Average pilots found the SPAD 12 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[edit]

Capt. Charles Biddle's 13th Aero Squadron SPAD S.XII, showing the slight positive stagger of the wings.
Closeup of Capt. Biddle in his SPAD S.XII.

No units were entirely equipped with SPAD 12s.[citation needed] 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, 8 being recorded on strength in April and again in October; this may be contrasted with the thousands of SPAD 7s and SPAD 13s 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 aircraft, which was given the number "0", and primarily flown by the 13th's Charles John Biddle [1], who ended up with a total of seven confirmed victories in World War I.

Six or more are said to have been held by the Red Army.[citation needed]

Operators[edit]

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

Specifications (S.XII)[edit]

Data from The Complete Book of Fighters [6]

General characteristics

Performance

Armament

See also[edit]

Related development

References[edit]

Notes
  1. ^ "The Cannon Pioneers". 
  2. ^ SPAD XII/XIII aces of World War I. p. 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. ^ a b Bruce 1982, p.560.
  6. ^ Green and Swanborough 1994, p.542-543.
Bibliography
  • Taylor, John W. R., and Jean Alexander. "Combat Aircraft of the World" New York: G.P. Putnam's Sons, 1969 Library of Congress Catalog Card Number 68-25459 (Pg.127)
  • Bruce, J.M. The Aeroplanes of the Royal Flying Corps (Military Wing). London:Putnam, 1982. ISBN 0-370-30084-X.
  • 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.