Cannons Post 1900: M61 Vulcan

The M61 is a hydraulically driven, six barreled, air cooled, and electrically powered Gatling style-cannon. It is the main cannon attachment for U.S. fixed wing aircraft, and has been for the past 50 years.

The M61 was developed after World War II as the brainchild of the United States Army. They began to think of the future of military aircraft guns. Their plan: to combine an extremely high rate of fire with exceptional reliability. The problem was that the high speeds of a jet-engine fighter aircraft would make it much more difficult without a much higher volume of fire. It was inspired by the designs of the Mauser MG213C, among other German guns.

In 1946, the Army issued General Electric Armament Division a contract for what was called “Project Vulcan”. It was to be a six-barreled weapon capable of firing 6,000 rounds per minute. The first aircraft to adopt this cannon was the F-104 Starfighter.

The M61 did suffer problems with the linked ammunition, as it was prone to foreign object damage and misfeed. They corrected it with a linkless feed  system for the newer M61A1, which became the standard armament of U.S. fighter aircraft.

Social Impact of Cannons

Cannons revolutionized the way people fought and defended. Once impenetrable castle walls and citadels that took months, even years to conquer were now easier to capture. Towns were now more vulnerable to successful sieges and raids. Cannons forced castle architects to go back to the drawing board, both literally and figuratively, and redesign castle walls because the walls were tall, flat and easy targets for the cannons. Many responded by thickening castle walls with piles of dirt called ramparts. Most of the time, ramparts were proven to be ineffective because they weakened the building material rather than strengthening it. Others dug deeper and wider moats or had rounded walls built. Rounded walls were created to try to make a “glancing shot” rather than a direct hit that a flat wall would end up taking, and were effective designs. The negative of rounded walls was that they were often too expensive for villages/towns/cities to build.
Leon Battista Alberti, an Italian author, artist and architect, among other things, wrote the De re aedificatoria, which were five requirements that castles would need to meet in order to successfully defend against cannon attacks. These were:

1) Fortification walls facing gunpowder weapons should be both short enough to easily see the ground below them, and wide enough to withstand the impact of cannonballs.

2) Artillery towers projecting at an angle beyond the walls should be added to the fortification- this would not only protect the fortification itself but also keep offensive guns at bay and cover blind spots along the fortress walls,

3) Angled bastions projecting out at regular intervals from the fortress wall should be built, giving increasing flanking cross-fire along the surface of those walls,

4) As time passed, further refinements should be added to the fortification: wide and deep ditches along the walls to keep enemy artillery at a distance and to cut down on mining with detached bastions built beyond those ditches to further impede enemy artillery attacks, and

5) Extensions should be built to these fortifications, complete with crownworks or hornworks, to protect these outside strategic areas.

Cannons Pre 1800: Fire-lance: The "Father" of the Cannon

The beginning of the cannon dates back to the 10th century. Cannons were the descendants of the fire-lance (or the firespear), which was a Chinese spear attached to a bamboo tube with gunpowder inside the chamber. These shot poison darts and small projectiles with fire.

Originally used for hand to hand combat, the gunpowder was designed to give an edge to the user in close combat. Inventors soon saw the opportunity due to the chamber/gunpowder design to make it into what it became. It saw the most use during the early Song Dynasty. It was good for:
shooting enemies trying to scale walls
holding an enemy at bay
Also, the fire-lance was very effective when it was fired in volleys.
The fire lance is often remembered for paving the way for the development of not only cannons, but for firearms and other artillery.