Richard Gatling's venerable multi-barreled gun was initially slow to find an audience, but once it did, it projected its influence on a global scale. From the American West to Africa, Europe and Asia, the expeditious and rhythmic roar of gunfire at a cyclic rate had become a battlefield fixture by the late 19th century.
The fire superiority of Gatlings came with a cost, though. The guns were cumbersome beasts most commonly mounted on wheeled platforms and towed into battle in the same manner as an artillery piece. Arguably the most poignant example of their predisposition for immobility was their absence on a Montana battlefield in June 1876 when Lt. Col. George Armstrong Custer left behind the 7th Cavalry's Gatlings to pursue Sitting Bull near the Little Bighorn River, resulting in nearly 150 years of Monday-morning quarterbacking on Custer's decision to opt for speed and mobility over firepower in the battle history records as his last.
Gatling's 19th century gun wasn't by definition a machine gun as it required external power for operation — most commonly provided by the gun's crew using a hand crank (although Gatling patented a design incorporating an electric motor in 1893). The technological evolution of warfare never sits on its hands, and by 1911, all models of Gatling's gun were deemed obsolete by the United States military, with many unceremoniously destroyed for scrap in favor of more portable recoil-operated, single-barreled machine guns such as Hiram Maxim's design.
Gatling's gun and its principles of operation would lie dormant for 36 years until the newly formed U.S. Air Force spearheaded a post-Word War II resurgence of interest in pursuit of developmental aircraft gun platforms. World War II had identified the vulnerability of U.S. fighter aircraft such as the P-47 and P-51 when compared to their Axis aircraft adversaries; the aforementioned U.S. aircraft's .50-caliber main armament was found lacking when compared to the longer-range cannon main armament of many Axis warplanes. Looking toward future engagements, the Air Force determined that underpowered guns were only part of the problem. Aerial warfare was changing. The development of jet engines was increasing the speed of military aircraft, and prevailing logic dictated that a higher volume of fire would be required to effectively place hits on the next generation of warplanes.
The Air Force's concept may sound uncomplicated in theory but was more complex in execution, as increasing the rate of fire of a single-barreled cannon was likely to negatively impact reliablity while greatly accelerating barrel wear. Ironically, resurrecting Richard Gatling's "obsolete" 19th-century design mitigated many of the developmental pitfalls of the high-speed aerial cannon on the Air Force's wish list, dramatically increasing the cannon's reliable rate of fire while dividing barrel wear equally amongst multiple barrels.
The characteristics that contributed to the demise of Richard Gatling's guns in the early 20th century were deemed less consequential for aircraft-mounted applications. Portability was not an issue, nor was the requirement for an external power source, and the potential performance of multi-barreled "superguns" could not be ignored. In 1950, the U.S. Army Ordnance Department, the Air Force and General Electric embarked on a joint venture to produce the next generation Gatling-type gun, code named "Project Vulcan," and by 1956, the F-104 Starfighter was the first U.S. warplane to be equipped with a fuselage-mounted six-barreled, 20mm cannon, dubbed the M61 Vulcan. Project Vulcan smashed its performance goals and delivered a platform with a rate of fire of 6,000 rounds per minute that is still in service today on the F-15 Eagle, F-16 Fighting Falcon, F/A-18 Hornet, F-22 Raptor and AC-130H Spectre.
No discussion about Gatling-type guns would be complete without including the GAU-8 Avenger. In 1976, the Air Force took delivery of its first aircraft that was specifically developed for a close air support role, the A-10 Thunderbolt II (affectionately dubbed "Warthog"). Inspiration for the A-10 was derived from the effectiveness of the German Junkers Ju 87, or Stuka, in a World War II close air support role, the poor survivability of the A-1 Skyraider in the Vietnam War, and the Cold War threat that the Soviet Union's megalithic mechanized armor resources posed to Europe. From the outset of development, the A-10 was designed as a highly maneuverable, highly survivable, highly lethal platform for deployment of the GAU-8 Avenger, a seven-barreled 30mm Gatling-type cannon capable of precision delivery of its armor-decimating payload at 3,900 rounds per minute. The Avenger cannon is such a monster that its recoil would cause the aircraft to yaw if the firing barrel were not aligned with the aircraft's centerline. It is known for emanating a legendary BRRRRRRRRRT when fired that is either beautiful or terrifying, depending on your relationship with the Warthog's pilot.
The Vietnam War saw the deployment of a scaled-down version of a Gatling-type gun based upon the success of the Vulcan cannon platform. The M134 is a six-barreled Gatling-type gun chambered in 7.62x51mm NATO and is capable of a rate of fire of 6,000 rounds per minute (although the M134 rate of fire is generally set between 2,000 and 4,000 rounds per minute). The versatile M134 platform, commonly referred to as a "minigun" in comparison to its bigger rotary cannon brothers, has seen service as a self-contained pod for fixed- and rotary-wing aircraft mount, and pedestal/pintle-mounted applications for employment on rotary-winged aircraft, wheeled vehicles and maritime operations.
To say that Gatling's design has caught its second wind is an understatement of the highest order, but this is no attempt to be all-inclusive of the scope of Gatling-type platforms past, present or future â€¦ that could fill an entire magazine on its own. In the latter years of his life, Richard Gatling saw the relevance of his most prominent invention wane as a casualty to newer technology. Today, Gatling's rotary-barreled design remains integral to the world's most sophisticated weapon systems, including the F-35 Lightning II Joint Strike Fighter. One has to wonder what Gatling would think if he knew of the longevity and versatility of his invention, and that over 150 years after he built the first one, the Gatling gun is still spinning up to speed.