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The M61 Vulcan Cannon and F-104 Starfighter

By: Warren Gray

Copyright © 2021

“I could invent a machine, a gun, which could...enable one man to do as much battle duty as a hundred.”

— Dr. Richard Jordan Gatling, 1877.

This is the historic, true story of the world’s first modern, electric, high-speed, Gatling gun, the 20mm M61 Vulcan rotary cannon, and the fastest jet fighter aircraft in the world at that time, capable of Mach-2 airspeed, the sleek, beautiful F-104 Starfighter, which was specifically designed to carry the all-new, M61 cannon.

The world-famous, Gatling-gun series was invented in April 1861 by Doctor Richard Jordan Gatling, an inventor living in Indiana, and was initially produced as a towed, hand-cranked, six-barrel, .58-caliber weapon capable of firing at the rate of 200 rounds per minute, or 3.3 rounds per second. They saw very limited action during the Civil War, most notably with Union forces under General Benjamin F. Butler during the Siege of Petersburg, Virginia, in May 1864.

After the war, Colt-manufactured Gatling guns were produced in various calibers between 1874 and 1893, when the first electrically-powered version was introduced. The rotary weapon’s greatest and most-successful, combat deployment took place during the Spanish-American War, on July 1, 1898, when a battery of three Colt M1895 10-barrel Gatlings in .30-40 Krag, commanded by Lieutenant John Henry “Gatling Gun” Parker, provided extensive, suppressive fire against the determined, Spanish defenders at San Juan Hill and Kettle Hill, Cuba, from 600 yards away, during the famous, uphill charges of Lieutenant Colonel Theodore Roosevelt and his “Rough Riders.”

This Gatling Gun detachment fired a total of 18,000 rounds in just eight and a half minutes, wreaking horrific carnage. The guns became so hot that their barrels glowed red, and a captured, Spanish officer said that, “It was terrible when your guns opened, always.” Parker’s own after-action report stated that, “The guns were pushed right up in the hottest place there was in the battlefield...at the most-critical point in the battle...(and) so successfully subdued the Spanish fire that from that time to the capture of the practically-impregnable position was only eight and a half minutes.”

But, despite its successes, the weapon’s weight and cumbersome, artillery carriage hindered its mobility with infantry forces, especially over difficult terrain, and it was declared obsolete and retired by the U.S. Army in 1911, after lighter, cheaper, recoil-and-gas-operated machine guns came into use. It wasn’t until nearly a half-century later that the jet age of aerial warfare led to the greatest and most-successful, Gatling-style variant ever produced.

The advent of the jet-fighter age meant that aircraft guns would require a much higher rate of fire than traditional, single-barrel weapons in order to achieve an effective number of hits against an adversary’s aircraft, so in 1946, the U.S. Army Air Forces issued a contract for “Project Vulcan” to General Electric for a six-barrel, 20x102mm cannon, initially designated the T171 Vulcan, capable of firing up to 7,200 rounds per minute, or 120 rounds per second. The multiple barrels contributed to prolonged, weapon life by minimizing barrel erosion and heat generation, making it an extremely reliable weapon.

This stunning, new device resurrected the M1893 Gatling Gun with an electric motor, actually testing an M1903 Gatling Gun from a museum, and taking advantage of significant advances in metallurgy for stronger barrels and higher rates of fire. General Electric soon changed the cannon’s official designation from T171, indicating a “Test” prototype, to M61, befitting a military “Mark” or “Model” number, and the initial weapon was produced with a standardized, cyclic rate of 6,000 rounds per minute, or 100 rounds per second, usually firing at 70 rps during the first second, as it spins up to full, rotating speed. In actuality, though, a burst controller usually limits the number of rounds fired with each pull of the trigger to no more than 50, for barrel cooling.

The current ammunition standard is the low-drag, semi-armor-piercing, high-explosive-incendiary (SAPHEI) 20mm PGU-28/B round, with a respectable muzzle velocity of 3,450 feet per second.

But this innovative, new, Vulcan cannon wasn’t created in a vacuum. It was specifically designed to equip the extraordinary, Lockheed F-104 Starfighter, the fastest jet fighter in the world in 1958, when it made its debut. The sleek, streamlined, amazingly-beautiful, and incredibly-fast Starfighter was designed by chief Lockheed aeronautical engineer Clarence L. “Kelly” Johnson, who also designed the P-38 Lighting fighter of World War Two fame, the F-80 Shooting Star jet fighter, the C-130 Hercules transport aircraft, the U-2 Dragon Lady spy plane, the A-12 Archangel/Oxcart/Cygnus Mach 3+ reconnaissance aircraft for the CIA, and its all-black successor, the SR-71A Blackbird.

The Starfighter was originally conceived as a very high-speed, short-range, lightly-armed, high-altitude interceptor, the very first production aircraft to attain Mach-2+ airspeed and reach an altitude of 100,000 feet on its own power, establishing world records for speed, altitude, and time-to-climb. Its wings were extremely small, thin (almost razor-sharp on the leading edges), and canted 10 degrees downward to offset a rolling tendency. The single-engine (General Electric J79-GE-19 turbojet) fuselage was so long and sleek that Lockheed marketed the new fighter as “the missile with a man in it.”

But because it was a straight-line interceptor and not a tactical dogfighter, its turning performance was poor. It was armed with one M61 cannon with 725 rounds of 20mm ammunition, and either two or four heat-seeking, AIM-9BSidewinder air-to-air missiles, the first aircraft ever to be armed with the M61 or the Sidewinder. And because it was initially designed as a high-altitude interceptor, its early, Stanley C-1 ejection seat fired downward to clear the vertical tail surface of the aircraft. This became a severe problem during low-altitude emergencies, especially in Europe, where ultra-low-level flight was commonplace, so an upward-firing, Lockheed C-2 seat was later installed, and many of the export variants received improved, Martin Baker Mk. 7 seats.

The original, F-104AStarfighter entered U.S. Air Force service on February 26, 1958, and saw action just a few months later in the Second Taiwan Strait Crisis, although there were no direct engagements with enemy forces. Later that same year, Lockheed redesigned the entire airframe, based upon a proposed, F-104G NATO requirement (“G” for “Germany”), with a number of improvements, for adoption by our NATO allies in Europe, specifically for Germany, Belgium, Italy, and the Netherlands.

Problems with the linked-ammunition feeding system on the M61 Vulcan led to a modification to accommodate a linkless feed system for the F-104C by 1959, and the revised cannon was designated the M61A1, which is still in production today.

Next, 60 Air National Guard F-104As were deployed to Germany during the Berlin Crisis of 1961 (Operation Stair Step), when the Soviets cut off Allied access to the city. Their presence provided a powerful, intimidating, air-superiority, deterrent message, but once again, there were no direct, aerial engagements against Soviet forces, and the crisis ended in 1962.

By April 1965, the Vietnam War was escalating, and U.S. Air Force F-104C Starfighters were deployed to Vietnam, where they flew 5,206 combat sorties, recording no air-to-air kills, and losing 14 aircraft to all causes, only one of which was shot down by an enemy J-6 (MiG-19) fighter. This disappointing performance led the Air Force to wind down Starfighter operations, and retire them from active service by 1969.

The F-104A finally achieved some limited, combat success with the Pakistani Air Force in the Indo-Pakistani War of 1965, shooting down an Indian Dassault Mystère IV over West Pakistan with an AIM-9B Sidewinder, thus scoring the world’s first kill by any Mach-2 fighter, the world’s first Sidewinder kill, and the Pakistani Air Force’s first air-to-air victory. But two days later, in another Mystère and Starfighter encounter, both planes damaged each other, and both crashed.

On January 13, 1967, amid the Taiwan Strait Conflict, four Taiwanese F-104Gs engaged and shot down two communist Chinese J-6/MiG-19 fighters, but one of the F-104s failed to return to base, and was listed as missing in action.

During this same period, in the mid-1960s, the F-104G had become the primary, fighter aircraft of Germany (since 1961), Belgium, Italy, the Netherlands, and Canada, as a low-level, multi-role, nuclear-capable, fighter-bomber, and due to the severe, air defense threat from Soviet forces just across the East German and Czech borders, much of the NATO flight training took place at very low altitudes, to avoid enemy missiles in combat. This often occurred in hilly terrain, and in the typically-cloudy, overcast, weather conditions of Western Europe. There were hundreds of accidents, crashes, and fatalities, with the Germans alone losing 116 pilots, and the Starfighter accrued the worst safety record of any of the “century-series” (F-100 through F-117) fighters.

The German media at the time dubbed the F-104G the Witwenmacher (“Widowmaker,”) or Fliegender Sarg  (“Flying Coffin”), and even the Canadians, who flew Starfighters from two bases in Germany, disparagingly called it the “Lawn Dart,” or the “Aluminum Death Tube.”  The world’s top-scoring, fighter ace of all time, Major Erich Hartmann, a Messerschmitt Bf 109Kpilot with 352 confirmed kills against Soviet aircraft to his credit during World War Two, was illegally held in a Soviet prison for 10 years after the war, and joined the West German Air Force soon after his release in 1955.

Promoted to full colonel, Hartmann commanded one of the first, post-war, jet fighter wings from 1959 to 1962, and was an outspoken critic of the F-104, which he deemed wholly unsafe for combat duties, with poor handling characteristics. This did not prove popular with his superiors, and he was given early retirement in 1970.

During the Indo-Pakistani War of 1971, the Pakistani Air Force again flew F-104As into battle, resulting in the first-ever, aerial combat between Mach-2 Starfighters and Soviet, Mach-2-capable, MiG-21FLFishbed-D jet fighters, with the Pakistanis losing two, and possibly four, F-104s in December 1971.

Ultimately, it was the Italian Air Force that produced and flew the most-advanced version (150 constructed) of the Starfighter in 1985, the F-104S-ASA/M, which was finally equipped with a modern, Fiat R21G/M1, pulse-Doppler, lookdown-shootdown radar, AIM-9LSuper Sidewinder all-aspect, heat-seeking missiles, and radar-guided, Selenia Aspide (“Asp”) medium-range missiles. These remained on active duty until October 2004, and were the last F-104s worldwide to be retired from military service.

All told, there were 2,578 F-104 Starfighters produced, mostly (over 2,000) for NATO nations, and it flew with the air forces of Belgium, Canada, Denmark, (West) Germany, Greece, Italy, Japan, Jordan, Netherlands, Norway, Pakistan, Spain, Taiwan, Turkey, and the United States. As of 2019, 12 privately-owned, airworthy F-104s remained in the United States, with their M61A1 Vulcan guns either deactivated or removed.

During and after its service aboard the F-104 Starfighter, however, the M61 Vulcan cannon proved to be an amazing, success story. It first saw aerial combat over North Vietnam in April 1965, resulting in three enemy MiG-17 Fresco fighters shot down by U.S. Air Force F-105 Thunderchiefs (“Thuds”) in a confusing dogfight, although no American pilot claimed a kill. The first confirmed, Vulcan kill came in June 1966, by Major Fred Tracy, flying another F-105D. During the Vietnam War, U.S. fighters scored 39 total victories with the M61A1gun.

It was used on the F-104 Starfighter, F-105D/F Thunderchief, F-106A Delta Dart, F-107A, F-111A Aardvark, F-4C/D (SUU-16/Aor SUU-23/A gun pods only) Phantom II, F-4E/F Phantom II, A-7D Corsair II, B-52HStratofortress (tail gun only, later removed), B-57GTropic Moon III night-interdiction aircraft (downward-swiveling, turret gun), B-58A Hustler (tail gun only), AC-119K Stinger gunship, AC-130A/E/H Spectre gunships, F-14A/B/D Tomcat, F-15A/B/C/DEagle, F-15E Strike Eagle, F-16 Fighting Falcon, YF-17A Cobra, Mitsubishi F-1, Italian AMX/A-11B Ghibli fighter, Taiwanese F-CK-1 Brave Hawk fighter, F/A-18 Hornet/Super Hornet (Super Hornet uses lighter M61A2), and F-22A Raptor stealth fighter (M61A2), YF-23AGray Ghost stealth fighter (planned, but never produced), M163 and M167 Vulcan Air Defense Systems (VADS, until 1994), and Navy Mk. 15 Phalanx weapon system. The M61A1 has been continually produced by General Dynamics since 1993, and continues to be tremendously successful. The M61A2 gun is 20-percent lighter, and fires at 6,600 rpm, which is 10-percent faster.

The Vulcan gun has been exported to Australia, Bahrain, Belgium, Botswana, Canada, Chile, Denmark, Ecuador, Egypt, Finland, Germany, Greece, Honduras, Indonesia, Iran, Iraq, Israel, Italy, Japan, Jordan, Kuwait, Malaysia, Morocco, Netherlands, Norway, Oman, Pakistan, Poland, Portugal, Romania, Saudi Arabia, Singapore, South Korea, Spain, Sudan, Switzerland, Taiwan, Thailand, Tunisia, Turkey, United Arab Emirates, United Kingdom, Uruguay, Venezuela, and Yemen.

In 2017, the sophisticated, computerized, “Death Claw” system was devised. This is not an actual weapon, but an automated, aiming system for M61A1/A2 and GAU-22/A rotary cannon in jet fighters. Steve Trimble wrote for Aviation Week and Space Technology magazine on January 27, 2020 that, “The Digitally-Enhanced, Aiming-Through-Control-Law (‘Death Claw’) system is in development...(at) the U.S. Air Force Test Pilot School...As a new, automated flight mode, it solves a practical problem for pilots of F-16s and potentially other fly-by-wire fighters.

“The F-16’s sensors and flight computer can precisely calculate where the F-16 needs to be pointed for the 20mm rounds from the fighter’s M61 cannon to hit a moving target in the air or on the ground. But the computer still relies on the human pilot to accurately point the aircraft at the spot indicated on the gunsight pipper on the head-up display. The answer seems obvious. Add an ‘auto-gunnery mode’ to the flight-control law, and allow the autopilot to point the aircraft when the gun is engaged.

“The Death Claw demonstration conducted 12 test flights in November 2017 to January 2018...(and) accuracy was calculated based on how closely the aircraft was pointed compared to the gunsight pipper...The autopilot proved (several times) more accurate than the pilot at aiming the aircraft...Lockheed Martin’s Skunk Works (their Advanced Development Programs [ADP] center) is now working on an improved, operational version of the new, autopilot gunnery mode.”

My favorite, Cold-War, M61A1Vulcan cannon story took place in 1984, during an exercise on Ramstein Air Base, West Germany. The base command post received a report that a simulated, seven-man, Russian SpetsNaz commando team had breached the perimeter fence line in a wooded part of the airfield, and they were attacking the Air Force security police patrols in that area, who required urgent assistance.

Fortunately, the U.S. Army’s 2nd Battalion, 60th Air Defense Artillery Regiment had a detachment of four M163A2Vulcan Air Defense System (VADS) mobile guns and four MIM-72G Chaparral mobile, heat-seeking-missile launchers permanently defending Ramstein, and the clever captain in charge devised a bold solution. Although the M61 Vulcan cannon was originally designed as an air-to-air weapon, and then later reconfigured as the M163 surface-to-air system, this officer was able to think outside the box, and rapidly deployed two of his Vulcans to the perimeter fence line, where they simulated engaging the enemy commando team in a lethal, surface-to-surface mode, with a devastating crossfire of 20mm cannon projectiles that instantly wiped out the intruding, SpetsNaz forces!

My favorite, F-104 Cold War-story goes like this: It was April 1984, on a cool, springtime, Saturday morning, and I was driving from Ramstein to Fliegerhorst Kaserne (U.S. Army airfield) in Hanau for a college class, in my European-specification, silver, Mitsubishi Colt Turbo subcompact hatchback. This tiny car had a 1.4-liter engine with 105 horsepower (50-percent more power than the non-turbo models), nine psi of boost pressure, front-wheel drive, Michelin XVS high-speed tires, a factory hood scoop, a Thrush ImporTurbo low-restriction muffler (my own modification), and it weighed a mere 1,800 pounds. Car magazines in those days called it a “pocket rocket,” but my coworkers said it was “like going 400 miles per hour in a beer can.” It was a great, little car, especially for driving on the German autobahns, where there are no speed limits.

The Colt Turbo would cruise all day at 115 miles per hour, and topped out at 120, but on this particular, winter day, I was cruising at a leisurely 105 miles per hour, in no particular hurry. I was on Autobahn 63 near Alzey, headed northeast, toward Frankfurt and Hanau, when I detected something very low over the distant hills in my left, peripheral vision. Part of my intelligence-specialist job with a USAF fighter squadron at that time was teaching aircraft recognition to fighter pilots, and I immediately identified this terrain-hugging object as a green-and-gray-camouflaged, German Luftwaffe (Air Force) F-104G Starfighter, flying at about 50 feet altitude and 580 knots (667 mph) airspeed, directly toward the autobahn ahead of me.

This was a fairly normal, flight profile in those days, since East Germany and Czechoslovakia were very heavily defended by Russian-made, SA-2 Guideline through SA-19 Grison surface-to-air missiles (and everything in between), as well as ZSU-23-4 Shilka and 2S6 Tunguska mobile gun systems, so flying more than 250 feet over enemy territory was simply unsurvivable, but with 50 feet calculated as a 95-percent survival rate. So, the Germans routinely trained exactly the same way they would have to fight World War Three in Europe, at breathtakingly, death-defyingly, ultra-low altitude.

It didn’t take very long for me to realize that the German pilot and I would soon “merge” in a crossing, low-level pass just ahead, and surely enough, his howling F-104G blasted low overhead at about Mach .82, casting a fleeting shadow through my glass sunroof for a split-second as he thundered past me, with his hot jetwash pummeling the right side of my car at 105 mph! I was all over the road for the next three seconds, thankful that there were no other motorists in the immediate vicinity, and I backed off the accelerator and wound it down to a gentle 90 mph as I regained control of the vehicle. Naturally, I couldn’t see his face, but I’m sure the Luftwaffe pilot was smiling when he realized that he’d just buzzed me from so strikingly low overhead.

In conclusion, jet fighters may come and go as the years go by, but the iconic, multi-barrel, Gatling-Gun remains one of those rare weapons that is instantly and universally recognizable, and essentially unchanged with the passage of time, except for an electric motor, used in one form or another for the past 128 years. The very names “Gatling Gun” and “Vulcan Cannon” both conjure up vivid images of fearsome, fire-breathing, high-speed, rotary machine guns or cannon, designed to instill fear in the enemy and maximize hit probability against moving targets in the air or on the ground. The need for such highly-efficient weapons of war remains undiminished over time.

Warren Gray is a retired, U.S. Air Force intelligence officer with experience in joint special operations and counterterrorism. He served in Europe and the Middle East, earned Air Force and Navy parachutist wings, and four college degrees, including a Master of Aeronautical Science degree, and was a distinguished graduate of the Air Force Intelligence Operations Specialist Course, and the USAF Combat Targeting School. He is currently a published author and historian. You may visit his web site at: warrengray54.vistaprintdigital.com.

 
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