M61 Vulcan
General Electric · Machine Gun · In Service · 1959
Also known as: Vulcan, M61, M61A1, M61A2, Project Vulcan
Overview
The M61 Vulcan is a six-barrel, 20x102mm electric Gatling-style autocannon developed by General Electric between 1946 and 1959 under the U.S. Air Force's Project Vulcan. It is the standard internal cannon of nearly all U.S. fighter aircraft built since the 1960s, including the F-104 Starfighter, F-105 Thunderchief, F-4 Phantom II (in pod and internal mountings), F-14 Tomcat, F-15 Eagle, F-16 Fighting Falcon, F/A-18 Hornet/Super Hornet, and F-22 Raptor. The cannon achieves a cyclic rate of 6,000 rounds per minute (4,000 rpm in some early aircraft applications, 6,600 rpm in the lightweight M61A2), making it one of the highest-rate-of-fire weapons ever fielded. The action uses an externally-supplied hydraulic, electric, or pneumatic motor to spin the six-barrel cluster; each barrel fires once per revolution at the 12 o'clock position, then ejects, extracts, and chambers as it rotates around to fire again. The 20x102mm cartridge produces approximately 54 kJ of muzzle energy per round and at full cyclic rate the M61 delivers over 5 megajoules of energy per second to the target. Beyond aircraft applications, the M61 is the heart of the Mk 15 Phalanx Close-In Weapon System (CIWS) which provides last-ditch missile defense for U.S. and allied warships, and the towed M167 / self-propelled M163 Vulcan Air Defense Systems used by the U.S. Army from 1968 through the 2000s. It remains in active service with the U.S. armed forces and over a dozen allied nations more than six decades after its introduction.
Specifications
| Weight (empty) | 112500 g (3968.3 oz) |
| Overall Length | 1827 mm (71.93") |
| Barrel Length | 1520 mm (59.84") |
| Action Type | Electric Gatling |
| Firing Mechanism | Externally Powered |
| Trigger Type | Automatic Only |
| Magazine Type | Belt |
| Muzzle Velocity | 1030 m/s (3379 fps) |
| Muzzle Energy | 54100 J (39902 ft·lbf) |
| Effective Range | 2000 m (2187 yd) |
| Maximum Range | 5500 m (6015 yd) |
| Rate of Fire | 6000 rpm |
| Barrel Rifling | Right Hand |
| Number of Grooves | 9 |
| Frame Material | Steel |
| Barrel Material | Steel |
| Finish | Phosphate |
Calibers
- 20x102mm · primary · 20mm — also known as 20mm Vulcan, 20x102, 20mm Aircraft
Features
- Firing modes: Full Automatic
- Feed systems: Linkless Feed System, Linked Belt Optional, Drum Magazine 500 To 1000 Rounds
- Safety mechanisms: External Power Required, Interlock Safety, Bolt Position Sensor
- Features: Six Barrel Rotary Gatling, Hydraulically Powered, Electrically Powered Alternative, Pneumatically Powered Alternative, Linkless Feed System, Progressive Rifling Twist, Aircraft Internal Mount, Naval Phalanx Ciws Mount, Land Based Air Defense Mount
Variants
- M61A1 — Improved Linkless Feed
- M61A2 — Lightweight F22 Raptor
- GAU-4 / M130 — Self Powered Gas Operated
- M168 — Vulcan Air Defense System
- Mk 15 Phalanx CIWS — Naval Close In Weapon
Service history
Operators
- United States Air Force · adopted 1959 · as M61
- United States Navy · adopted 1959 · as M61 / Mk 15 Phalanx
- United States Army · adopted 1968 · as M168 (Vulcan Air Defense System)
- Japan Air Self-Defense Force · as JM61
- Republic of Korea Air Force · as M61
- Israeli Air Force · as M61
- Royal Australian Air Force · as M61
- Republic of China Air Force · as M61
- Royal Saudi Air Force · as M61
Conflicts
- Vietnam War (1959-1975)
- Six-Day War (1967)
- Yom Kippur War (1973)
- Falklands War (1982)
- Gulf War (1990-1991)
- Operation Allied Force (Yugoslavia) (1999)
- War in Afghanistan (2001-2021)
- Iraq War (2003-2011)
Production
Production years: 1959-present
Manufactured by General Electric, then General Dynamics Armament and Technical Products, and Lockheed Martin. Total production not publicly disclosed but exceeds tens of thousands across all variants and aircraft installations.
Origin
Country of origin: United States
Designer: General Electric Armament Systems Division
Notes
Although classified as a 'cannon' due to its 20mm bore, the M61 follows the same Gatling principle as the smaller M134. Three power options exist: electric (most aircraft applications), hydraulic (F-15, F-16), and pneumatic (some pod-mounted variants). The M61A1 introduced the linkless feed system that eliminated the link-jam failures of the original belt-fed M61. The lightweight M61A2 used in the F-22 Raptor reduces weight from 112 to 92 kg via thinner barrels and has a slightly higher cyclic rate. Spin-up time is approximately 0.4 seconds. A typical fighter aircraft load is 510-940 rounds, providing 5-9 seconds of total firing time. The Mk 15 Phalanx CIWS combines an M61A1 with self-contained search and tracking radars for autonomous engagement of incoming missiles and aircraft. Project Vulcan was prompted by Korean War experience showing that subsonic .50-caliber Browning aircraft guns lacked the rate of fire and lethality required for jet-vs-jet combat.
Background
Project Vulcan was named for the Roman god of fire and forge, but the gun's defining moment came in 1956 when General Electric demonstrated a prototype that fired a one-second burst at 6,000 rpm - 100 rounds in a single second of trigger-press, the entire ammunition load of a WWII fighter expended faster than the pilot could blink. The M61 was so revolutionary it forced the entire world's air forces to follow suit; the Soviets responded with the GSh-6-23, the French with the DEFA 554, and to this day the Vulcan's distinctive ripping-cloth sound is the audio signature of American air power.