F-111 Aardvark, one of the legends of the Cold War, "Vark the Assassin"

One of the legends of the Cold War was the F-111 Aardvark, also known as the "Assassin Vark". Its pilots and maintainers called it the "Assassin Vark".

The F-111 was the first aircraft in the world to use the new variable geometry technology or "swing wings". It was also the first to use turbofan engines and the first to introduce terrain tracking radar technology into the theater of operations. It was the first in its class to have an ejectable crew cabin.

The F-111 Aardvark may be retired, but its legend lives on

The General Dynamics F-111 Aardvark was a "low-altitude attack/strike aircraft" born to meet the requirements of the US Air Force and Navy. Despite its troubled adolescence, it evolved into a capable high-tech "night bomber" with a sleek and elegant profile and decades of service.

Cold War Origins of the F-111

The F-111 Aardvark was the result of the US Department of Defense's Tactical Fighter Experimental or TFX program. After the Soviet Union shot down a U-2 spy plane in May 1960, the US Air Force turned its attention from high-altitude bombers susceptible to missile attack to aircraft capable of low-altitude, high-speed infiltration into enemy depths. This concept was based on the fact that fighters of this capability could more easily evade radar detection at low altitude.

To this end, the TFX (Tactical Fighter Experimental) program, which emerged in the early 60s, first had to develop a bomber for deep isolation/attack missions. General Dynamics was selected from competing applicants such as Boeing and Lockheed to design, develop and produce the required low-altitude bomber.

One of the things that gave General Dynamics an advantage was that the plans for its prototypes envisioned similar components for the versions of the aircraft required by the US Air Force and Navy. In designing the F-111, General Dynamics worked with Northrop Grumman to design the aircraft's landing gear, assembly and fuselage. This pair of aerospace defense industry experts also worked together to test the F-111.

F-111 Experienced a Troubled Design Period Due to Differing Operational Requirements 

In the early 1960s, the US Air Force realized that new, radar-guided surface-to-air missiles like the Soviet SA-2 could reach the B-52 and other slow, high-altitude bombers. In response, it devised a new concept: a smaller, long-range supersonic bomber that could glide close to the ground below the detection angle of radar systems. At the same time, the US Navy was looking for a fast, long-range, carrier-based interceptor armed with air-to-air missiles that could neutralize Soviet bombers from a distance.

The US Department of Defense believed that a single aircraft could meet both requirements, thus saving development costs. The US Army and Navy were reluctant to compromise on their vision, but were forced to cooperate on the so-called TFX (Tactical Fighter) program. In 1962, a contract was signed with General Dynamics. Because the design was smaller than the Air Force strategic bombers and avoided the "attack-attack" designation used by the Navy, General Dynamics assigned the code "F-Fighter/Av-Bomber" to this new fighter to be designed. 

Design Features that Revolutionized the 1960s

"Folding Wings", the first in the world...

First in the world in the use of "Turbofan Engine"...

"Launchable Cockpit", the first in the world in the example of a spacecraft capsule...

"Terrain Tracking Radar", the first in the world...

F-18, F-111, T-38

The F-111 was built around two powerful but fuel-efficient TF30 turbofan engines with new afterburner technology. Earlier turbojet engines provided the thrust needed for supersonic flight, but lost efficiency at low speeds. Turbofans were much more efficient in this regime and were therefore a good choice for aircraft that would use short runways and carrier-based aircraft.

A large airframe could carry bomb loads of up to 31,000 pounds on internal fuel for missions within a range of 2,500 miles, with an additional 1,000 miles with external fuel tanks. Classified as a Fighter F, but actually a full Attack A, this large aircraft had an empty weight of twenty tons, more than double its fully loaded weight.

Internal Weapons Bay

The F-111 had an internal weapons bay capable of carrying bombs, an attachable and detachable 20 mm M61 cannon or auxiliary fuel tanks. The internal bay could carry conventional and nuclear bombs.

External Payload Capacity

Each wing was equipped with four lower wing struts. The inner two struts on each wing were rotated to align with the fuselage, while the outer two struts were fixed. The capacity of each strut was 5,000 pounds (2,300 kilograms). 

The design of the F-111's fuselage prevented the transportation of external munitions/weapons under the fuselage, but two stations were available on the underside for electronic countermeasures (ECM) pods and/or data link pods. 

There were five variants of the F-111 Aardvark

The 563 individual F-111s produced were divided into five categories: F111, BF111, CEF-111A Raven, F-111K and Boeing AFTI/F-111A Aardvark.

EF-111A Raven

The F-111B was used by the US Navy. The F-111C was used in Australia. The Raven was used by the US Air Force. The F-111K was a proposed variant for the UK's Royal Air Force (RAF), but it never materialized - it died before it was born.

As for the Boeing AFTI/F-111A, NASA and the US Air Force Flight Dynamics Laboratory used this single aircraft variant for research purposes from 1985 to 1988. Other notable retirement dates were 1996 for the F-111F, '98 for the EF-111A and 2010 for the F-111C. 

The designers of the F-111 faced an important and critical challenge; they needed an aircraft that could fly at very high speeds, but still take off and land from a short runway. The use of smaller wings creates less drag, allowing the aircraft to fly faster, but it also creates less lift, requiring the aircraft to reach higher speeds before take-off, and therefore requires a longer runway. Yes, they were going to design a fast airplane, but this airplane would need long runways for takeoff and landing. However, one of the design requirements was that this aircraft could also take off and land on short runways, so how were the designers going to meet these two important customer requirements?

For example, the other supersonic fighter-bomber of the era, the F-105 Thunderchief, had very small wings and required runways longer than a minimum of a mile for takeoff, limiting the runways the aircraft could use and therefore limiting the elastic operational capability of US air power.

The designers of the F-111 adopted new variable geometry technology, or "folding" wings. This system allowed the wings to swing outward during takeoff to create maximum lift, and then curve inward mid-flight to achieve higher speeds. The F-111 was the first aircraft in the world to use this technology. It pioneered a revolutionary design.

The F-111's Folding Wing Geometry.

Its key and revolutionary system was the "Terrain Tracking Radar".

A key innovation was the F-111's revolutionary terrain following radar (TFR), which mapped the ground directly in front of the aircraft and then automatically adjusted the flight path to avoid collision. This allowed the F-111s to fly as low as two hundred feet below the surface and make precise adjustments at high speed without crashing, even when flying at night or in bad weather. The F-111's ability to hunt in the dark, nose close to the ground, is what earned it the name "Aardvark".

Early F-111s showed promise, capable of flying above the speed of sound at Mach 1.2 at low altitude or more than twice that at high altitude (Mach 2.5), while requiring only a 2,000 ft runway for landing. It was the first tactical aircraft to fly from the United States to Europe without refueling in the air.

The two-man crew sat side by side in a cockpit compartment. If they needed to escape, a rocket would propel the pod upwards and then float to the ground on a parachute, just like a space capsule.

F-111 during low to high speed navigation with terrain tracking radar.

Footage of two USAF fliers leaving their aircraft with the capsule and landing safely on the ground in 1968.

However, the design of the F-111 was biased in favor of Air Force specifications. The carrier-based interceptor version, the F-111B, performed poorly in trials where it struggled to exceed Mach 1. This expensive and forced compromise version, the Navy version, was eventually shelved and millions of dollars were thrown away. However, many of the promising design elements of the F-111B were passed on to the F-14 Tomcat.

The Most Expensive Aircraft in Its Class at the Time

The price of the F-111 in 2023 was approximately $140 million. This is a significantly high price for a medium bomber even today. 

It entered service with the US Air Force and Navy in 1967. In the US Navy, the F-111B was not considered successful and the serial production of this variant was canceled. It was decommissioned from the US Air Force in 1996 and from the RAAF (Royal Australian Air Force), the only force flying it outside the US, and the Australian Air Force in 2010. A total of 563 were produced in multiple variants.

Few aircraft have been as controversial as the F-111. Intended to be the first joint fighter development program, the F-111 was the largest and most expensive aircraft program of its time. It also came at a time of drastic changes in military strategy, program management, US Department of Defense acquisition strategy and technology. For this reason, the F-111 project also served as a reference for later aircraft programs.

Specifically Designed to Fly Low and Fast

The F-111 was a twin-engine, single-tailed, two-seat fighter/bomber with a folding wing. Conceived in the 1950s as a means of nuclear retaliation, it was specifically designed to fly low and fast. In the 1960s, however, American military strategy shifted its emphasis to more conventional operations, including missions such as air dominance and ground attack.

As military strategy changed radically, so did management techniques in the US Department of Defense. In 1961, a revolution in procurement policy was initiated in the form of "systems analysis". DOD strove to ensure that military procurement reflected real military strategy and did so in the most cost-effective way possible. One of these cost-effective measures was a joint aircraft for the Air Force and Navy, despite strong objections from the US Air Force and Navy. Unfortunately, in its desire for change, DOD underestimated the limits of force requirements. The problems of managing a joint program plagued the F-111 project until the US Navy finally withdrew from the program in 1968.

When the joint program was launched in 1961 as the TFX, the F-111 was intended to serve as a multi-role fighter for both forces. Much of the technology was available at the time to build tactical fighters similar to the very successful F-15 and F-16 of the 1970s, but the F-111 remained representative of the 1950s priority to engage in the nuclear mission. Although designated as a multi-role fighter/bomber, it is actually a bomber or attack aircraft as defined in its design requirements. The difference between the F-111's design requirements and its intended use caused confusion about its role. Furthermore, the F-111's design requirements were free of rigorous analysis, trade-offs, or prioritization, leaving little room for design flexibility for the primary contractors, General Dynamics and Grumman. 

Despite the constraints, the F-111 has managed to meet, or come very close to meeting, its demanding requirements. The F-111 could fly at supersonic speeds over treetops and take off from short runways or aircraft carriers. It could carry a significant payload over long distances and was a valuable combat performer for the United States from Vietnam to the First Gulf War.

Technically, the F-111 combined many innovative features. Many lessons learned from the F-111 were incorporated into the design of the F-14, F-15 and F-16.

Given the poorly compiled requirements, the F-111 was a well-designed air-to-ground attack/attack aircraft that was also intended to serve as a common multi-role fighter. It proved quite capable in the attack role, but due to its weight and lack of maneuverability, the F-111 was inadequate in the air-to-air role and consequently was never used in that role. 

The experience of the F-111 influenced not only its successors, the F-14 for the US Navy and the F-15 for the US Air Force, but also the latest venture in joint programs, the F-35 Joint Strike Fighter.

Primary Mission

The F-111's primary mission was to serve as a transoceanic supersonic nuclear bomber capable of deep penetration of Soviet airspace.

The intended mission of the F-111 was to serve as a joint service fighter/bomber that could fulfill the different missions of each force and at the same time allow partnering for cost savings. For the Air Force, the F-111's primary mission was to serve as a transoceanic supersonic nuclear bomber capable of deep penetration of Soviet airspace. The Air Force also hoped it would serve as a supersonic air-to-air fighter. For the Navy, the F-111's mission was fleet defense against Soviet bombers capable of launching anti-ship missiles.

As a common aircraft, the F-111 was to be sold to the United States Air Force and Navy and the armed forces of the Western Allies, such as Great Britain and Australia. The US Air Force wanted to replace its existing fleet of F-100, F-101 and F-105 fighters/bombers, while the Navy planned to replace its F-4 and F-8 fighters. In total, the original contract envisioned a requirement for approximately 900 aircraft between the two forces.

Geopolitical Context

The F-111 was designed as a nuclear attack bomber at the height of the Cold War in the 1950s. During the Cold War, the United States relied on its nuclear weapons to counter the overwhelming conventional military superiority of the Soviet Union at the time. Even before the Cold War, the United States had relied on such "asymmetry" - from production capacity during World War II to nuclear capacity during the Cold War - as a way to avoid the enormous expense of a standing army. As the nuclear arms race progressed, the United States settled on a strategy known as "massive retaliation", in which it threatened a full-scale nuclear counterattack against the Soviet Union for attacking the West with nuclear or conventional weapons. The nuclear strategy was chosen as the most viable option, and conventional weapons were accordingly de-emphasized.

Military Strategy

Before the advent of intercontinental ballistic missiles (ICBMs), the backbone of America's nuclear deterrent was the Air Force's Strategic Air Command. SAC's heavy bombers flew higher and farther than aircraft had ever flown before, and were capable of striking the heart of the Soviet Union from bases in the United States. The SAC bombers flew at very high altitudes at high subsonic speeds and tried to stay out of range of enemy defenses. But as early warning radars and surface-to-air missiles improved dramatically, the United States was forced to choose an alternative tactic: "flying swiftly below radar coverage". Since radars could still only see the horizon, the lower and possibly faster an aircraft could fly, the deeper it could penetrate enemy airspace.

Served in Vietnam

The US Air Force did not have an auspicious start to the war with F-111s. After six squadrons of F-111As deployed to Vietnam in 1968, three of them crashed in only fifty-five missions, all accidents linked to defective wing stabilizers. The Air Force was forced to withdraw the F-111 and correct the defect at a cost of $100 million.

With its wing stabilizers replaced, the F-111 Aardvark showed its potential in Vietnam. At night, the F-111s slipped under North Vietnam's vast radar network, hitting North Vietnamese air bases and air defense batteries, weakening resistance to incoming B-52 strikes.

The F-111s did not require the fighter escort, electronic warfare support or aerial refueling required by other bombers and could operate in inclement weather. In 4,000 combat sorties during the war, only six F-111s were lost in combat, one of the lowest casualty rates of the war.

El Dorado Canyon Raid

The F-111 would return to the stage of world history after a bomb attack on the La Belle nightclub by Libyan agents in Berlin in 1986 killed two US soldiers. The US President ordered an attack on Libyan dictator Muammar al-Qaddafi's personal compound near Tripoli, code-named El Dorado Canyon. 

A series of twenty-five SAM batteries in different compounds were defending Tripoli. A squadron of eighteen F-111Fs carried out the main attack, joined by four EF-111 Raven to electronically jam the defense radars. 

Since the United States could not obtain approval for the raid from mainland European countries, the Aardvarks took off from England and had to circumnavigate Spain, bringing the total flight time to thirteen hours. In total, they would have to refuel six times on the round trip. It was the longest-range combat mission in history.

F-111s Over Iraq

On January 17, 1991, on the opening night of Operation Desert Storm, F-111s swept across the desert at low altitude, targeting Iraqi air defenses and key military installations with laser-guided bombs. Meanwhile, EF-111 Ravens escorted strike packages of coalition aircraft flying deep into Iraq, their jammers disabling Iraqi air defense radars. A total of sixty-six F-111Fs and 18 F-111Es were deployed in the 1991 Iraq War, flying 5,000 mission sorties.

F-111 with F-4 on the left and F-15 on the right. Mirage-III on the far right

Rival and allied aircraft with the same purpose as the F-111

While the F-111 is retiring, its rival, a similar aircraft, is in use today. The Russian Sukhoi Su-24 Fencer was designed shortly after the F-111 and is quite similar in appearance and role, right down to the folding wings. It is hardly the Aardvark's equal in terms of range, speed or weapons load. It was actively used in the conflicts over Syria, Chechnya, Libya, Afghanistan and Ukraine.

The Panavia Tornado, designed and built by the Allies Britain, Germany and Italy, is an F-111-like aircraft with folding wings and terrain tracking radar, effective in low-altitude, high-speed attack missions.