Fort Wynyard is home not only to the Cape Garrison Artillery and the Heritage Group, but also to a most amazing piece of Artillery – a 9.2 inch Disappearing Gun
A disappearing gun (often called a disappearing carriage) was a type of heavy (mainly coastal) artillery used in the past for which the gun carriage enabled the gun to rotate backwards and down into a pit protected by a wall (the parapet) or a bunker after it was fired. This retraction lowered the gun from view by the enemy while it was being reloaded.
It also made reloading easier, since it lowered the breech to a level just above the loading platform, and shells could be rolled right up to the open breech for loading and ramming. Although it had these advantages, the disappearing carriage was also a complicated mechanism. In the U.S., disappearing carriages were mostly withdrawn from active service by the early 1920s.
The disappearing gun was usually moved down behind the parapet or into its protective housing by the force of its own recoil, which (on many models) lifted a counterweight. Before firing, the crew tripped a catch on the counterweight, causing it to fall into a well at the center of the gun position and move the gun back up “into battery” (firing position).
Some disappearing guns also used compressed air, while a few were built to be raised by steam.
The disappearing carriage had several principal advantages:
- It afforded the gun crew protection from direct fire by raising the gun over the parapet (or wall in front of the gun) only when it was to be fired, otherwise leaving it at a lower level, where it was also able to be loaded easily.
- With its guns in a retracted position (down behind the parapet), the battery was much harder to spot from the sea, making it a much harder target for attacking ships. Flat trajectory fire tended simply to fly over the battery, without damaging it.
- Interposing of a moving fulcrum between the gun and its platform lessened the strain on the latter and allowed it to be of lighter construction while limiting recoil travel.
- Simple, well protected earthen and masonry gun pits were much more economical to construct than the previous practice of constructing the standing heavy walls and fortified casemates of a more traditional gun emplacement.
- The entire battery could be hidden from view when not in use, unlike a traditional fort, enabling ambuscade fire.
The disappearing gun had several drawbacks as well:
- The carriage design restricted maximum elevation to under 20 degrees and thus lacked the necessary range to match newer naval guns entering service during the early part of the 20th century. The additional elevation gained by mounting the same gun on a later non-disappearing carriage increased their range.
- The time taken for the gun to swing up and down and be reloaded slowed the rate of fire. Surviving records indicate a rate of fire of 1 round per 1 to 2 minutes for an 8-inch (20 cm) gun, significantly slower than less complicated guns.
- The improvement in the speed of warships demanded an increased rate of firing. The disappearing gun was at a disadvantage compared with a gun that stayed in position as one could not aim or reposition a disappearing gun while it was in the lowered position. The gunner still had to climb atop the weapon via an elevated platform to sight and lay the weapon after it was returned to firing position, or receive fire control information (range and bearing) transmitted from a remote location.
- Their relative size and complexity also made them expensive compared with non-disappearing mounts.
Disappearing guns as a functioning concept were invented in the 1860s by Captain (later Sir) Alexander Moncrieff, who built on his observations in the Crimean War to improve on existing designs for a gun carriage capable of rising over a parapet before being reloaded from behind cover. His key innovation was a counterweight system that raised the gun as well as controlled the recoil. Moncrieff promoted his system as an inexpensive and quickly constructed alternative to a more traditional gun emplacement.
Buffington and Crozier further refined the concept in the late 1880s by incorporating hydro-pneumatic recoil control to assist the counterweight action. The Buffington–Crozier Disappearing Carriage (1893) represented the zenith of disappearing gun carriages, and guns of up to 16-inch size were eventually mounted on such carriages. Disappearing guns were highly popular for a while in the British Empire, the United States and other countries. (Source – WikiPedia)