hw97karbine
Airman 1st Class
- 265
- Mar 23, 2025
Demonstration of the WWI SPAD S.XII main armament consisting of a manually-loaded 37mm SAMC cannon mounted between the cylinder banks of the Hispano-Suiza 8BeC V8 engine and firing through the hollow propeller shaft. The spent casings were ejected automatically.
The SPAD XII was inspired by the ideas of French flying ace Georges Guynemer, who proposed that a maneuverable single-seat aircraft be designed to carry a 37mm 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.
The gun chosen for the SPAD XII was not the old Hotchkiss cannon but a new 37mm 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, avoiding the problem of firing through the moving blades. 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 with a hollow propeller shaft for the cannon to fire through, and power the airframe, weighing 587 kilograms (1,294 lb) rather than 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, which also gave the SPAD XII a clockwise (seen "nose-on") rotating propeller.
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. 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. The cannon's breech mechanism protruded into the cockpit and prevented the use of a conventional stick to control the aircraft, adding to pilots' difficulties. The control setup reverted to a split setup on either side of the pilot, a la Deperdussin.
The SPAD XII was inspired by the ideas of French flying ace Georges Guynemer, who proposed that a maneuverable single-seat aircraft be designed to carry a 37mm 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.
The gun chosen for the SPAD XII was not the old Hotchkiss cannon but a new 37mm 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, avoiding the problem of firing through the moving blades. 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 with a hollow propeller shaft for the cannon to fire through, and power the airframe, weighing 587 kilograms (1,294 lb) rather than 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, which also gave the SPAD XII a clockwise (seen "nose-on") rotating propeller.
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. 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. The cannon's breech mechanism protruded into the cockpit and prevented the use of a conventional stick to control the aircraft, adding to pilots' difficulties. The control setup reverted to a split setup on either side of the pilot, a la Deperdussin.
